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10,806,002 | ACCEPTED | Off-ridge roof vent | An off-ridge roof vent includes a hood open along the sides and front and a rear flange for mounting the hood to a roof. A pair of side walls each includes lower flanges to mount to a flat roof and upper bent tabs that fit under the hood to provide a tight fit between the walls and hood. A front baffle wall extends upwardly from a flange and opening and extends under the hood and terminates in a channel to mount one edge of a screen and another channel is formed in a subtending wall from the hood to mount the other edge of the screen to prevent the entry of debris into the vented roof space. All of the flanges are connected and are in the same plane so that the vent may be attached to a flat roof. | 1. A roof vent adapted to be mounted to a roof comprising a hood member having a front portion defining a front opening and a rear portion mountable over an opening in a roof, a pair of spaced side wall members extending between said front and rear portions of said hood member, and a baffle wall spaced forwardly of said front portion of said hood member and extending substantially the width of said front opening to inhibit entry of wind into said front opening. 2. The roof vent as defined in claim 1 wherein said front portion of said hood member includes an elongate subtending front wall member. 3. The roof vent as defined in claim 2 wherein said front wall includes a lower elongate edge portion formed into a first channel open rearwardly extending substantially the complete width of said front wall. 4. The roof vent as defined in claim 1 wherein said baffle wall includes an upper edge portion and a lower edge portion, said upper edge portion of said baffle wall formed as a lip for diverting wind directed against said baffle wall upwardly to minimize the amount of such wind entering said front opening. 5. The roof vent as defined in claim 3 further including an elongate horizontal member extending the width of said baffle wall having a front edge portion integral with said lower edge portion of said baffle wall and a rear portion having a vertical disposed wall member, said wall member of said rear portion of said member including an upper edge portion formed as a second channel open forwardly extending substantially the width of said horizontal member. 6. The roof vent as defined in claim 5 further including a filter means mounted between said first and second channels. 7. The roof vent as defined in claim 6 wherein said filter means includes a screen member. 8. The roof vent as defined in claim 1 further including an elongate horizontal member extending the width of said baffle wall having a front edge portion integral with said lower edge portion of said baffle wall and a rear portion having a vertical disposed wall member, said wall member of said rear portion of said member including an upper edge portion formed as a second channel open forwardly extending substantially the width of said horizontal member. 9. The roof vent as defined in claim 1 wherein each said side wall member includes a lower edge portion and an upper edge portion, said lower edge portion including a first bendable planar flange member being movable 90° to locate said flange member against a surface of a roof. 10. The roof vent as defined in claim 9 wherein said upper edge portion of each said side wall includes at least one second bendable planar flange member being movable 90° to locate said second flange member inside said hood member. 11. A roof vent adapted to be mounted to a roof comprising a hood member having front and rear portions and a pair of parallel spaced edge portions integral with said front and rear portions for locating said hood member over an opening in a roof, said front portion being spaced away from a surface of a roof when said hood member is mounted to a roof to define a pair of spaced side openings and a front opening, a pair of side wall members for covering a respective said side opening, and a baffle wall spaced forwardly of said front portion of said hood member, said baffle wall extending substantially the width of said front opening to inhibit entry of wind into said front opening. 12. The roof vent as defined in claim 11 wherein said front portion of said hood member includes a subtending front wall member extending between said edge portions. 13. The roof vent as defined in claim 12 wherein said front wall includes a lower elongate edge portion formed into a first channel open rearward extending substantially the complete width of said front wall. 14. The roof vent as defined in claim 11 wherein said baffle wall includes an upper edge portion and a lower edge portion, said upper edge portion of said baffle wall formed as a lip for diverting wind directed against said baffle wall upwardly to minimize the amount of such wind entering said front opening. 15. The roof vent as defined in claim 13 further including an elongate horizontal member extending the width of said baffle wall having a front edge portion integral with said lower edge portion of said baffle wall and a rear portion having a vertical disposed wall member, said wall member of said rear portion of said member including an upper edge portion formed as a second channel open forward extending substantially the width of said horizontal member. 16. The roof vent as defined in claim 15 further including a filter means mounted between said first and second channels. 17. The roof vent as defined in claim 16 wherein said filter means includes a screen member. 18. The roof vent as defined in claim 11 further including an elongate horizontal member extending the width of said baffle wall having a front edge portion integral with said lower edge portion of said baffle wall and a rear portion having a vertical disposed wall member, said wall member of said rear portion of said member including an upper edge portion formed as a second channel extending substantially the width of said horizontal member. 19. The roof vent as defined in claim 11 wherein each said side wall member includes a lower edge portion and an upper edge portion, said lower edge portion including a first bendable planar flange member being movable 90° to locate said flange member against a surface of a roof. 20. The roof vent as defined in claim 19 wherein said upper edge portion of each said side wall includes at least one second bendable planar flange member being movable 90° to locate said second flange member inside said hood member. 21. A roof vent adapted to be mounted to a flat surface of a roof comprising a hood member having front and rear portions and a pair of parallel spaced edge portions integral with said front and rear portions for disposing said hood member over an opening in a roof, said front portion being spaced away from a flat surface of a roof when said hood member is mounted to a roof to define a pair of spaced side openings and a front opening, a pair of side wall members for covering a respective said side opening, and a baffle wall spaced forwardly of said front portion of said hood member, said baffle wall extending substantially the width of said front opening to inhibit entry of wind into said front opening, said rear portion of said hood member including a rear flange having opposite end portions, each said side wall member including a lower flange having a front end portion and a rear end portion, said baffle wall including a lower flange having opposite end portions, each said rear end portion of said lower flange of each said side wall member being connected to a respective said end portion of said rear flange of said hood member and each said end portion of said lower flange of said baffle wall being connected to one said front end portion of said lower flange of a corresponding said side wall member, said flanges being coplanar adapted to be affixed on a flat surface of a roof. 22. The roof vent as defined in claim 21 wherein each said side wall member includes a plurality of spaced flanges, said spaced flanges being connected to a respective edge portion of said hood member. | CROSS-REFERENCE TO RELATED APPLICATION Not Applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable. REFERENCE TO A MICROFICHE APPENDIX Not Applicable. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vents to be installed in building roofs and particularly to off-ridge roof vents employing apparatus to minimize the entrance of moisture and debris into the vented space. 2. Relevant Art A wide variety of roof vents exist that are comprised of a complex set of elements that are not easily assembled or installed. In addition, baffles are needed to control airflow and prevent entrance into the vented space of water and debris. BRIEF SUMMARY OF THE INVENTION A roof vent adapted to be mounted to a roof comprising a hood member having a front portion defining a front opening and a rear portion mountable over an opening in a roof, a pair of spaced side wall members extending between the front and rear portions of the hood member, and a baffle wall spaced forwardly of the front portion of the hood member and extending substantially the width of the front opening to inhibit entry of wind into the front opening. The front portion of the hood member includes an elongate subtending front wall member. The front wall includes a lower elongate edge portion formed into a first channel open rearwardly extending substantially the complete width of the front wall. The baffle wall includes an upper edge portion and a lower edge portion. The upper edge portion of the baffle wall formed as a lip for diverting wind directed against the baffle wall upwardly to minimize the amount of such wind entering the front opening. Also included is an elongate horizontal member extending the width of the baffle wall having a front edge portion integral with the lower edge portion of the baffle wall and a rear portion having a vertical disposed wall member. The wall member of the rear portion of the member includes an upper edge portion formed as a second channel open forwardly extending substantially the width of the horizontal member. A filter means is mounted between the first and second channels and includes a screen member. Each side wall member includes a lower edge portion and an upper edge portion, the lower edge portion including a first bendable planar flange member being movable 90° to locate the flange member against a surface of a roof. The upper edge portion of each side wall includes at least one second bendable planar flange member being movable 90° to locate the second flange member inside the hood member. A roof vent adapted to be mounted to a roof vent adapted to be mounted to a roof comprising a hood member having front and rear portions and a pair of parallel spaced edge portions integral with the rear portion for mounting the hood member over an opening in a roof. The front portion is spaced away from a surface of a roof when the hood member is mounted to a roof to define a pair of spaced side openings and a front opening, a pair of side wall members for covering a respective side opening, and a baffle wall spaced forwardly of the front portion of the hood member, the baffle wall extending substantially the width of the front opening to inhibit entry of wind into the front opening. The front portion of the hood member includes a subtending front wall member extending between the edge portions. The front wall includes a lower elongate edge portion formed into a first channel open rearward extending substantially the complete width of the front wall. The baffle wall includes an upper edge portion formed as a lip for diverting wind directed against the baffle wall upwardly to minimize the amount of such wind entering the front opening. An elongate horizontal member extends the width of the baffle wall having a front edge portion integral with the lower edge portion of the baffle wall and a rear portion having a vertical disposed wall member, the wall member of the rear portion of the member including an upper edge portion formed as a second channel open forward extending substantially the width of the horizontal member. Filter means is mounted between the first and second channels and includes a screen member. Each side wall member includes a lower edge portion and an upper edge portion, the lower edge portion including a first bendable planar flange member being movable 90° to locate the flange member against a surface of a roof. The upper edge portion of each side wall includes at least one second bendable planar flange member being movable 90° to locate the second flange member inside the hood member. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which: FIG. 1 is a perspective view of the off-ridge roof vent in accord with the present invention; FIG. 2 is a side elevational pictorial view of two of the components of the vent of FIG. 1; FIG. 3 is a plan view of one end cap of the vent of FIG. 1; and FIG. 4 is a view of another end cap of the vent of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, the off-ridge roof vent in accord with the present invention is shown at numeral 10. A hood member 11 includes a flat horizontal portion 12 and a rear downwardly sloped portion 13 terminating in flange 14. Two substantially identical side end cap members 15 (FIGS. 3 and 4) each include an inwardly bendable edge portion 16 adjacent portion 13 and another inwardly bendable edge portion 17 adjacent portion 12. A lower outwardly bendable flange 18 is used to mount the vent 10 to a roof. Further detail of the construction of the vent 10 is illustrated in FIG. 2. A front vertical wall portion 19 extends downwardly from portion 12 and terminates in a channel 20 formed by crimping the lower edge of wall 19. A separate metal sheet is shaped to make baffle assembly including external wind baffle wall 21 bound by an upper angled lip 22 and a lower lip 23 formed by crimping the sheet to form flat floor member 24 and a further 90° bend to form a vertical rear wall 25 having an upper edge crimped to form a channel 26. Channels 20 and 26 are used to carry a planar screen 27. The space between channel 20 and upper lip 22 of baffle wall 21 defines an opening 28 into vent 10. Preferably, the hood member of the vent 10 including portions 12, 13, 14, 19 and 20 are formed of a single sheet of metal. Similarly, baffle assembly portions 21, 22, 23, 24, 25 and 26 are also formed from a single sheet of metal. End caps 15 are also formed from a single sheet of metal and further include a forward edge portion 29 and a foldable tab 30 that with edge portions 16 and 17 is bent 90° to fit flush against the inner surfaces of respective portions 12, 13 and 19. The various parts are secured together by appropriate fastening means such as S-lok connections that brad the pieces together without penetrating either piece and/or blind rivets securing overlapping tabs or flanges at appropriate locations and/or spot welding, as is common in the art. The vent 10 consists of four main components: a hood member 11 shaped into a flat portion 12, a sloping portion 13, a rear flange 14 and front wall with a channel 20 for carrying one edge of screen 27; two end caps 15; and the baffle assembly providing wall 21 and one channel 26 for carrying one edge of a screen 27. While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to vents to be installed in building roofs and particularly to off-ridge roof vents employing apparatus to minimize the entrance of moisture and debris into the vented space. 2. Relevant Art A wide variety of roof vents exist that are comprised of a complex set of elements that are not easily assembled or installed. In addition, baffles are needed to control airflow and prevent entrance into the vented space of water and debris. | <SOH> BRIEF SUMMARY OF THE INVENTION <EOH>A roof vent adapted to be mounted to a roof comprising a hood member having a front portion defining a front opening and a rear portion mountable over an opening in a roof, a pair of spaced side wall members extending between the front and rear portions of the hood member, and a baffle wall spaced forwardly of the front portion of the hood member and extending substantially the width of the front opening to inhibit entry of wind into the front opening. The front portion of the hood member includes an elongate subtending front wall member. The front wall includes a lower elongate edge portion formed into a first channel open rearwardly extending substantially the complete width of the front wall. The baffle wall includes an upper edge portion and a lower edge portion. The upper edge portion of the baffle wall formed as a lip for diverting wind directed against the baffle wall upwardly to minimize the amount of such wind entering the front opening. Also included is an elongate horizontal member extending the width of the baffle wall having a front edge portion integral with the lower edge portion of the baffle wall and a rear portion having a vertical disposed wall member. The wall member of the rear portion of the member includes an upper edge portion formed as a second channel open forwardly extending substantially the width of the horizontal member. A filter means is mounted between the first and second channels and includes a screen member. Each side wall member includes a lower edge portion and an upper edge portion, the lower edge portion including a first bendable planar flange member being movable 90° to locate the flange member against a surface of a roof. The upper edge portion of each side wall includes at least one second bendable planar flange member being movable 90° to locate the second flange member inside the hood member. A roof vent adapted to be mounted to a roof vent adapted to be mounted to a roof comprising a hood member having front and rear portions and a pair of parallel spaced edge portions integral with the rear portion for mounting the hood member over an opening in a roof. The front portion is spaced away from a surface of a roof when the hood member is mounted to a roof to define a pair of spaced side openings and a front opening, a pair of side wall members for covering a respective side opening, and a baffle wall spaced forwardly of the front portion of the hood member, the baffle wall extending substantially the width of the front opening to inhibit entry of wind into the front opening. The front portion of the hood member includes a subtending front wall member extending between the edge portions. The front wall includes a lower elongate edge portion formed into a first channel open rearward extending substantially the complete width of the front wall. The baffle wall includes an upper edge portion formed as a lip for diverting wind directed against the baffle wall upwardly to minimize the amount of such wind entering the front opening. An elongate horizontal member extends the width of the baffle wall having a front edge portion integral with the lower edge portion of the baffle wall and a rear portion having a vertical disposed wall member, the wall member of the rear portion of the member including an upper edge portion formed as a second channel open forward extending substantially the width of the horizontal member. Filter means is mounted between the first and second channels and includes a screen member. Each side wall member includes a lower edge portion and an upper edge portion, the lower edge portion including a first bendable planar flange member being movable 90° to locate the flange member against a surface of a roof. The upper edge portion of each side wall includes at least one second bendable planar flange member being movable 90° to locate the second flange member inside the hood member. | 20040322 | 20060516 | 20051020 | 73380.0 | 4 | BOLES, DEREK | OFF-RIDGE ROOF VENT | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,806,312 | ACCEPTED | Arrangement in an access router for optimizing mobile router connections based on delegated network prefixes | An access router of a local mobile network includes a delegation resource for delegating address prefixes and a routing resource configured for parsing reverse routing headers from received data packets. The delegation resource supplies each mobile router attaching to the local mobile network with a corresponding unique delegated address prefix within an available network prefix for use within the local mobile network. Each mobile router attached to the access router via another mobile router utilizes a reverse routing header to establish a tunnel with the access router, enabling the access router to source route messages to the mobile router via its corresponding local care-of address and next-hop addresses specified in the reverse routing header. Each mobile router creates a remote care-of address based on the delegated address prefix, minimizing the need for binding updates with the corresponding home agent as the mobile router moves within the local mobile network. | 1. A method in an access router, the method comprising: supplying to a first mobile router a delegated address prefix, based on attachment by the first mobile router to one of the access router and a second mobile router attached to the access router, each mobile router in a local mobile network serviced by the access router receiving a corresponding unique delegated address prefix for use within the local mobile network; and registering a remote care-of address having the delegated address prefix with a prescribed home agent of the first mobile router, to register a reachability of the first mobile router. 2. The method of claim 1, further comprising outputting a router advertisement message having a prefix option and a tree information option, the prefix option specifying an available network prefix for use within the local mobile network, the tree information option specifying that the access router is a top level router and configured as a delegating router for supplying the delegated address prefix. 3. The method of claim 2, wherein the supplying step includes: receiving from the first mobile router a request for the delegated address prefix and that includes a reverse routing header specifying a path to the first mobile router including a local care-of address within an address space of the available network prefix, the request further including a source address field specifying a first hop for the path; assigning the delegated address prefix to the first mobile router, from an aggregation of prefixes within the available network prefix, by updating a binding cache entry with the delegated address prefix reachable via the local care-of address; and sending to the first hop for the path the delegated address prefix for the first mobile router in a packet including a source route header specifying the path. 4. The method of claim 3, wherein the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within the address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 5. The method of claim 4, wherein the registering step includes forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 6. The method of claim 5, wherein the forwarding step includes: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 7. The method of claim 4, further comprising: receiving a second binding update message from the first mobile router specifying a second local care-of address within the address space of the available network prefix and distinct from the second delegated address prefix, the second binding update superseding the local care-of address; and updating the binding cache entry with the delegated address prefix and the first mobile router reachable via the second local care-of address. 8. The method of claim 1, further comprising outputting a router advertisement message specifying an available network prefix for use within the local mobile network, and wherein: the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within an address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 9. The method of claim 8, wherein the registering step includes forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 10. The method of claim 9, wherein the forwarding step includes: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 11. A method in a mobile router, the method comprising: detecting a router advertisement message output by a second mobile router serving as an attachment router for the mobile router, the router advertisement message having a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes; generating a local care-of address based on the first network prefix; outputting a request for a delegated prefix from the access router via the second mobile router; receiving the delegated prefix assigned by the access router, the delegated prefix distinct from the first network prefix; and advertising the delegated prefix on ingress links of the mobile router. 12. The method of claim 11, further comprising: generating a home care-of address based on the delegated prefix; and sending via the second mobile router a binding update message to a home agent, specifying at least one of the mobile router and a native mobile network prefix assigned by the home agent to the mobile router is reachable via the home care-of address. 13. The method of claim 12, wherein the outputting and sending steps each include inserting a reverse routing header that includes the local care-of address and a prescribed number of empty slots for the second mobile router and any intervening hops along a path to the access router. 14. The method of claim 12, further comprising: detecting a second router advertisement message output by the access router and having a second prefix option and the tree information option identifying the access router as the top level mobile router and the delegating router, the second prefix option specifying an available network prefix for use within a local mobile network serviced by the access router; attaching to the access router by: (1) replacing the local care-of address with a new local care-of address based on the available network prefix, and (2) sending to the access router a binding update message that specifies that the mobile router and the delegated prefix is reachable via the new local care-of address. 15. An access router configured for providing connectivity to a wide area packet switched network for a local mobile network, the access router including: a delegation resource configured for supplying to each mobile router a corresponding delegated address prefix, each of the delegated address prefixes within an available network prefix for use within the local mobile network; and a routing resource including a routing table configured for storing, for each delegated address prefix, a corresponding local care-of address for reaching the corresponding mobile router in the local mobile network. 16. The access router of claim 15, wherein the routing resource includes a router advertisement resource configured for outputting a router advertisement message including a prefix option and a tree information option, the prefix option specifying the available network prefix for use within the local mobile network, the tree information option specifying that the access router is a top level router and configured as a delegating router for supplying the delegated address prefix. 17. The access router of claim 16, wherein: the routing resource includes a reverse routing header resource configured for establishing a source route for reaching a corresponding one of the local care-of addresses based on successive next-hop addresses specified within a reverse routing header of a received message from the corresponding mobile router; the delegation resource is configured for receiving from a first of the mobile routers a request for a corresponding first delegated address prefix and that includes a reverse routing header specifying a path to the first mobile router including a local care-of address within an address space of the available network prefix, the request further including a source address field specifying a first hop for the path; the delegation resource is configured for assigning the first delegated address prefix to the first mobile router, from an aggregation of prefixes within the available network prefix, by updating a binding cache entry with the first delegated address prefix reachable via the local care-of address; the delegation resource sending, to the first hop for the path, the first the delegated address prefix for the first mobile router in a packet including a source route header specifying the path. 18. The access router of claim 17, wherein the local care-of address is within the address space of a second delegated address prefix assigned to a corresponding second one of the mobile routers. 19. The access router of claim 18, wherein: the routing resource is configured for receiving a binding update message from the first mobile router and destined for a prescribed home agent, specifying at least one of the first mobile router and a native mobile network prefix assigned by the prescribed home agent to the first mobile router is reachable via a home care-of address having the first delegated address prefix; the reverse routing header resource configured for removing from the binding update message an attached reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path; the routing resource configured for inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 20. The access router of claim 17, wherein: the routing resource is configured for receiving a second binding update message from the first mobile router specifying a second local care-of address within the address space of the available network prefix and distinct from the second delegated address prefix, the second binding update superseding the local care-of address; and the routing resource configured for updating the binding cache entry with the first delegated address prefix and the first mobile router reachable via the second local care-of address. 21. A mobile router comprising: an egress interface configured for receiving a router advertisement message output by a second mobile router serving as an attachment router for the mobile router, the router advertisement message having a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes; and a routing resource including: (1) a mobility resource configured for generating a local care-of address based on the first network prefix, and outputting via the egress interface a request for a delegated prefix from the access router via the second mobile router, the mobility interface configured for receiving the delegated prefix, distinct from the first network prefix, from the access router, and (2) an advertisement resource configured for outputting, on an ingress interface, an advertisement message specifying the delegated prefix. 22. The mobile router of claim 21, wherein the mobility resource is configured for generating a home care-of address based on the delegated prefix, and sending via the second mobile router a binding update message to a home agent, the binding update message specifying at least one of the mobile router and a native mobile network prefix assigned to the mobile router by the home agent is reachable via the home care-of address. 23. The mobile router of claim 22, wherein the mobility resource is configured for inserting a reverse routing header that includes the local care-of address and a prescribed number of empty slots for the second mobile router and any intervening hops along a path to the access router. 24. The mobile router of claim 22, wherein: the egress interface is configured for receiving a second router advertisement message output by the access router and having a second prefix option and the tree information option identifying the access router as the top level mobile router and the delegating router, the second prefix option specifying an available network prefix for use within a local mobile network serviced by the access router; the mobility resource is configured for to the access router by: (1) replacing the local care-of address with a new local care-of address based on the available network prefix, and (2) sending to the access router a binding update message that specifies that the mobile router and the delegated prefix is reachable via the new local care-of address. 25. A computer readable medium having stored thereon sequences of instructions for providing connectivity by an access router for a local mobile network, the sequences of instructions including instructions for: supplying to a first mobile router a delegated address prefix, based on attachment by the first mobile router to one of the access router and a second mobile router attached to the access router, each mobile router in a local mobile network serviced by the access router receiving a corresponding unique delegated address prefix for use within the local mobile network; and registering a remote care-of address having the delegated address prefix with a prescribed home agent of the first mobile router, to register a reachability of the first mobile router. 26. The medium of claim 25, further comprising instructions for outputting a router advertisement message having a prefix option and a tree information option, the prefix option specifying an available network prefix for use within the local mobile network, the tree information option specifying that the access router is a top level router and configured as a delegating router for supplying the delegated address prefix. 27. The medium of claim 26, wherein the supplying step includes: receiving from the first mobile router a request for the delegated address prefix and that includes a reverse routing header specifying a path to the first mobile router including a local care-of address within an address space of the available network prefix, the request further including a source address field specifying a first hop for the path; assigning the delegated address prefix to the first mobile router, from an aggregation of prefixes within the available network prefix, by updating a binding cache entry with the delegated address prefix reachable via the local care-of address; and sending to the first hop for the path the delegated address prefix for the first mobile router in a packet including a source route header specifying the path. 28. The medium of claim 27, wherein the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within the address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 29. The medium of claim 28, wherein the registering step includes forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 30. The medium of claim 29, wherein the forwarding step includes: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 31. The medium of claim 28, further comprising instructions for: receiving a second binding update message from the first mobile router specifying a second local care-of address within the address space of the available network prefix and distinct from the second delegated address prefix, the second binding update superseding the local care-of address; and updating the binding cache entry with the delegated address prefix and the first mobile router reachable via the second local care-of address. 32. The medium of claim 25, further comprising instructions for outputting a router advertisement message specifying an available network prefix for use within the local mobile network, and wherein: the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within an address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 33. The medium of claim 32, wherein the registering step includes forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 34. The medium of claim 33, wherein the forwarding step includes: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 35. A computer readable medium having stored thereon sequences of instructions for a mobile router to attach to a local mobile network, the sequences of instructions including instructions for: detecting a router advertisement message output by a second mobile router serving as an attachment router for the mobile router, the router advertisement message having a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes; generating a local care-of address based on the first network prefix; outputting a request for a delegated prefix from the access router via the second mobile router; receiving the delegated prefix assigned by the access router, the delegated prefix distinct from the first network prefix; and advertising the delegated prefix on ingress links of the mobile router. 36. The medium of claim 35, further comprising instructions for: generating a home care-of address based on the delegated prefix; and sending via the second mobile router a binding update message to a home agent, the binding update message specifying at least one of the mobile router and a native mobile network prefix assigned by the home agent to the mobile router is reachable via the home care-of address. 37. The medium of claim 36, wherein the outputting and sending steps each include inserting a reverse routing header that includes the local care-of address and a prescribed number of empty slots for the second mobile router and any intervening hops along a path to the access router. 38. The medium of claim 36, further comprising instructions for: detecting a second router advertisement message output by the access router and having a second prefix option and the tree information option identifying the access router as the top level mobile router and the delegating router, the second prefix option specifying an available network prefix for use within a local mobile network serviced by the access router; attaching to the access router by: (1) replacing the local care-of address with a new local care-of address based on the available network prefix, and (2) sending to the access router a binding update message that specifies that the mobile router and the delegated prefix is reachable via the new local care-of address. 39. An access router comprising: means for supplying to a first mobile router a delegated address prefix, based on attachment by the first mobile router to one of the access router and a second mobile router attached to the access router, each mobile router in a local mobile network serviced by the access router receiving a corresponding unique delegated address prefix for use within the local mobile network; and means for registering a remote care-of address having the delegated address prefix with a prescribed home agent of the first mobile router, to register a reachability of the first mobile router. 40. The access router of claim 39, wherein the registering means includes means for Outputting a router advertisement message having a prefix option and a tree information option, the prefix option specifying an available network prefix for use within the local mobile network, the tree information option specifying that the access router is a top level router and configured as a delegating router for supplying the delegated address prefix. 41. The access router of claim 40, wherein the supplying means is configured for: receiving from the first mobile router a request for the delegated address prefix and that includes a reverse routing header specifying a path to the first mobile router including a local care-of address within an address space of the available network prefix, the request further including a source address field specifying a first hop for the path; assigning the delegated address prefix to the first mobile router, from an aggregation of prefixes within the available network prefix, by updating a binding cache entry with the delegated address prefix reachable via the local care-of address; and sending to the first hop for the path the delegated address prefix for the first mobile router in a packet including a source route header specifying the path. 42. The access router of claim 41, wherein the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within the address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 43. The access router of claim 42, wherein the registering means is configured for forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 44. The access router of claim 43, wherein the registering means is configured for: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update nessage, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 45. The access router of claim 42, wherein the registering means is configured for: receiving a second binding update message from the first mobile router specifying a second local care-of address within the address space of the available network prefix and distinct from the second delegated address prefix, the second binding update superseding the local care-of address; and updating the binding cache entry with the delegated address prefix and the first mobile router reachable via the second local care-of address. 46. The access router of claim 39, wherein the registering means includes means for outputting a router advertisement message specifying an available network prefix for use within the local mobile network, and wherein: the second mobile router is assigned a second delegated address prefix distinct from the delegated address prefix and within an address space of the available network prefix, the local care-of address within the address space of the second delegated address prefix. 47. The access router of claim 46, wherein the registering means is configured for forwarding a binding update message from the first mobile router to the prescribed home agent, the binding update message specifying at least one of the first mobile router and a native mobile network prefix assigned to the first mobile router by the home agent is reachable via the remote care-of address. 48. The access router of claim 47, wherein the registering means is configured for forwarding the binding update message based on: removing from the binding update message the reverse routing header, and storing in a binding cache entry that the local care-of address is reachable via the path including the first hop for the path, inserting an address of the access router in the source address field of the binding update message, and forwarding the binding update message without the reverse routing header to the prescribed home agent. 49. A mobile router comprising: means for detecting a router advertisement message output by a second mobile router serving as an attachment router for the mobile router, the router advertisement message having a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes, the detecting means including means for generating a local care-of address based on the first network prefix; means for outputting a request for a delegated prefix from the access router via the second mobile router, and for receiving the delegated prefix assigned by the access router, the delegated prefix distinct from the first network prefix; and means for advertising the delegated prefix on ingress links of the mobile router. 50. The mobile router of claim 49, wherein: the generating means is configured for generating a home care-of address based on the delegated prefix; and the outputting means is configured for sending via the second mobile router a binding update message to a home agent, the binding update message specifying at least one of the mobile router and a native mobile network prefix assigned to the mobile router by the home agent is reachable via the home care-of address. 51. The mobile router of claim 50, wherein the detecting means includes means for inserting, into the request and the binding update message, a reverse routing header that includes the local care-of address and a prescribed number of empty slots for the second mobile router and any intervening hops along a path to the access router. 52. The mobile router of claim 50, wherein: the detecting means is configured for detecting a second router advertisement message output by the access router and having a second prefix option and the tree information option identifying the access router as the top level mobile router and the delegating router, the second prefix option specifying an available network prefix for use within a local mobile network serviced by the access router; the generating means is configured for attaching to the access router by: (1) replacing the local care-of address with a new local care-of address based on the available network prefix, and (2) sending to the access router a binding update message that specifies that the mobile router and the delegated prefix is reachable via the new local care-of address. | CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority from Provisional Application 60/518,346, filed Nov. 10, 2003, the disclosure of which is incorporated in its entirety herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to route optimization by a mobile router of a mobile network, for example a mobile IP network (NEMO) or an Internet Protocol (IP) based mobile ad hoc network (MANET), and an access router providing an attachment point to a wide area network such as the Internet. 2. Description of the Related Art Proposals have been made by Internet Engineering Task Force (IETF) groups for improved mobility support of Internet Protocol (IP) based mobile devices (e.g., laptops, IP phones, personal digital assistants, etc.) in an effort to provide continuous Internet Protocol (IP) based connectivity. The IETF has two working groups focusing on mobile networks, a Mobile Ad-hoc Networks (MANET) Working Group that is working to develop standardized MANET routing specification(s) for adoption by the IETF, and NEMO (mobile networks). NEMO uses Mobile IP (MIP) to provide connectivity between mobile networks and the infrastructure (e.g., the Internet). The key component in NEMO is a mobile router that handles MIP on behalf of the mobile networks that it serves. A “Mobile IPv6” protocol is disclosed in an Internet Draft by Johnson et al., entitled “Mobility Support in IPv6”, available on the World Wide Web at the address: http://www.ietf.org/internet-drafts/draft-ietf-mobileip-ipv6-24.txt (the disclosure of which is incorporated in its entirety herein by reference). According to Johnson et al., the Mobile IPv6 protocol enables a mobile node to move from one link to another without changing the mobile node's IP address. In particular, the mobile node is assigned a “home address”. The “home address” is an IP address assigned to the mobile node within its home subnet prefix on its home link. While a mobile node is at home, packets addressed to its home address are routed to the mobile node's home link, using conventional Internet routing mechanisms. The mobile node also is assigned a home agent for registering any care-of address used by the mobile node at its point of attachment to the Internet while the mobile node is away from its home link. A care-of address is an IP address associated with a mobile node that has the subnet prefix of a particular link away from its home link (i.e., a foreign link). A home agent is a router on a mobile node's home link with which the mobile node has registered its current care-of address. While the mobile node is away from its home link, the home agent intercepts packets on the home link destined to the mobile node's home address; the home agent encapsulates the packets, and tunnels the packets to the mobile node's registered care-of address. The NEMO working group has extended the features of Mobile IPv6 (which to date have been limited to an IPv6 mobile node such as a wireless laptop) to a mobile network based on providing routing protocols that enable the mobile router to attach to an access router and establish route optimization for the mobile router and its associated mobile network. One example of proposed solutions for route optimization in a nested mobile network is disclosed in the Internet Draft by Thubert et al., “Taxonomy of Route Optimization models in the Nemo Context”, available on the IETF website at http://www.ietf.org/internet-drafts/draft-thubert-nemo-ro-taxonomy-02.txt and the disclosure of which is incorporated in its entirety herein by reference (referred to hereinafter as “Thubert-RO”). In particular, Thubert-RO notes that NEMO enables Mobile Networks by extending Mobile IP to support Mobile Routers; Thubert-RO describes how Route Optimization as described in the context of MIPv6 can to be adapted for NEMO to optimize traffic routing between nodes in a mobile network and their correspondent nodes. Another example of a proposed solution for route optimization is disclosed in the Internet Draft by Thubert et al., “IPv6 Reverse Routing Header and its application to Mobile Networks” available on the IETF website at http://www.ietf.org/internet-drafts/draft-thubert-nemo-reverse-routing-header-04.txt and the disclosure of which is incorporated in its entirety herein by reference (referred to hereinafter as “Thubert-RRH”). Thubert-RRH discloses that Mobile IP can be extended to support mobile routers, and enable nested mobile networks, using a reverse routing header that eliminates the need for nested tunnels between mobile routers and their home agents, but rather enables use of a single tunnel between a mobile router and its associated home agent. One particular aspect of the above proposals is that the mobile router communicates with its associated home agent to ensure reachability between the mobile router and the wide area packet switched network (e.g., the Internet). It may be desirable in certain cases to reduce the necessity for a mobile router to establish a tunnel with its associated home agent in order to have connectivity with the wide area packet switched network. For example, it may be desirable in certain cases that a mobile router can establish anonymous route connections without notifying the home agent of the source of the route connections. It also may be desirable in certain cases that a mobile router can establish multiple attachments with different access routers as the mobile router moves (i.e., “roams”) across the respective service of the access routers, without the necessity of notifying the home agent of each attachment, especially when the attachment may be for only a transient interval. Other proposals attempt to minimize nesting of tunnels, as well as avoid a tunnel between a mobile router and its corresponding home agent, by adding prescribed operations to a top level mobile router of a mobile network. One example is described in the Internet Draft by Kang et al., “Route Optimization for Mobile Network by Using Bi-directional Between Home Agent and Top Level Mobile Router”, available on the World Wide Web at http://www.watersprings.org/pub/id/draft-hkang-nemo-ro-tlmr-00.txt and incorporated in its entirety herein by reference. Another example of minimizing nesting of tunnels and avoiding a tunnel between a mobile router and its corresponding home agent involves use of a mobility anchor point (MAP). A variation of the Mobile IPv6 protocol is disclosed in an IETF Internet Draft by Soliman et al., “Hierarchical Mobile IPv6 mobility management (HMIPv6)” June 2003, available on the World Wide Web at http://www.ietf.org/internet-drafts/draft-ietf-mobileip-hmipv6-08.txt and incorporated in its entirety herein by reference. The Internet Draft by Soliman et al. discloses a Mobility Anchor Point (MAP) within an IPv6 network that implements HMIPv6 by assigning a regional care-of address to mobile nodes within its address realm. Mobile nodes may thus use on-link care-of addresses for communications within the address realm of the MAP, and the regional care-of address for lPv6 communications outside the MAP address realm. As such, the MAP serves as a local home agent. Hence, a mobile node is always addressable by its “home address”: packets may be routed to the mobile node using this address regardless of the mobile node's current point of attachment to the Internet. The mobile node also may continue to communicate with other nodes (stationary or mobile) after moving to a new link. The movement of a mobile node away from its home link is thus transparent to transport and higher-layer protocols and applications. As apparent from the foregoing, however, Soliman et al. is limited to mobile nodes, and does not describe use of HMIP for a mobile router in a manner that could be applied to a mobile network served by the mobile router. However, route optimization has been described in the Internet Draft by Ohnishi et al., “HMlP based Route Optimization Method in a Mobile Network” available at the IETF website at http://www.ietf.org/intemet-drafts/draft-ohnishi-nemo-ro-hmip-00.txt and the disclosure of which is incorporated in its entirety herein by reference. Of particular interest is a proposal that describes using prefix delegation, such as Dynamic Host Configuration Protocol (DHCP): DHCP is described in Droms et al., “Dynamic Host Configuration Protocol for IPv6 (DHCPv6)”, published by the IETF as a Request for Comments (RFC) 3315 and available on the World Wide Web at http://www.ietf.org/rfc/rfc3315.txt (the disclosure of which is incorporated in its entirety herein by reference). Prefix delegation in DHCP is described in Troan et al., “IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6”, published by the IETF as RFC 3633 and available at the IETF website at http://www.ietf.org/rfc/rfc3633:.txt (the disclosure of which is incorporated in its entirety herein by reference). In particular, the Internet Draft by Lee et al., “Route Optimization for Mobile Nodes in Mobile Network based on Prefix Delegation”, available at the IETF website at http://www.ietf.org/internet-drafts/draft-leekj-nemo-ro-pd-02.txt (the disclosure of which is incorporated in its entirety herein by reference) discloses an access router that delegates a prefix to a top level mobile router. FIGS. 1 and 2 are diagrams from the above-incorporated Internet Draft by Lee et al. FIG. IIlustrates a network 10 having mobile routers 12a and 12b attached to their respective home agents 14a and 14b. The home agents 14a and 14b each provide a point of attachment in FIG. 1 between the respective mobile routers 12a and 12b and the Internet 16, enabling the mobile nodes 18 to communicate with a correspondent node 20. Each of the home agents 14a and 14b has a corresponding home address prefix: the home agent “HA-MR1” 14a has a home address prefix 22a of “1::”, and the home agent “HA-MR2” 14b has a home address prefix 22b of “2::”, according to the IPv6 addressing convention specified in RFC 3513, available on the Internet at http://www.ietf.org/rfc/rfc3513.txt (the disclosure of which is incorporated in its entirety herein by reference). Hence, the mobile routers “MR1” 12a and “MR2” 12b are assigned by their respective home agents 14a and 14b the mobile network prefixes 24a and 24b having respective values “1:1::” and “2:1::”. Consequently, the mobile routers 12a and 12b advertise their respective mobile network prefixes 24a and 24b to their respective attached nodes 18 and consequently form mobile networks 30a and 30b. FIG. 1 also illustrates an access router 26 having a corresponding local network 42, also referred to herein as a visited network, having a network prefix 28 with a value of “3::”. FIG. 2 illustrates a revised network topology 10′ based on the movement of the mobile routers 12a and 12b from their respective home agents 14a and 14b and attachment with the access router 26. As shown in FIG. 2, each mobile router (e.g., 12a and 12b) has a home address (HoA) (e.g., 34a, 34b) based on its corresponding home address prefix (e.g., 22a, 22b): the home address 34a of the mobile router (MR1) 12a has a value of “1::1” within the address space of the home address prefix 22a “1::”, and the home address 34b of the mobile router (MR2) 12b has a value of “2::3” within the address space of the home address prefix 22b “2::”. According to the Internet Draft by Lee et al., the mobile router 12a detects movement and obtains a delegated prefix (DP) 32a having a value of “3:1::” from the access router 26 according to a prefix delegation protocol such as DHCPv6. The detection of movement by the mobile router 12a is based on, for example, a detected loss of connectivity with the home agent 14a, detecting router advertisement messages from the access router 26, and attaching to the access router 26. In response to receiving the delegated prefix 32a, the mobile router 12a builds a care-of address (CoA) 36a within the network prefix 28, and performs a binding update with its home agent 14a to enable the home agent 14a to identify that the home address 34a of the mobile router 12a is reachable via the care-of address 36a. In response to assignment of the delegated prefix 32a, the mobile router 12a also outputs router advertisement messages that advertise the delegated prefix 32a, using a prescribed Delegated Prefix option. Note that the mobile router 12a also outputs router advertisement messages that advertise its mobile network prefix 24a. The second mobile router (MR2) 12b in response attaches to the mobile router 12a, and obtains from the mobile router 12a a sub-delegated prefix 32b having a value of “3:1:1::” and that is within the address space of the delegated prefix 32a “3:1::” assigned to the mobile router 12a. The mobile router 12b, having attached to the mobile router 12a, obtains a care-of address (CoA2) 36b based on the mobile network prefix 24a (based on the router advertisement message specifying the MNP 24a) and a care-of address (CoA1) 36c based on the delegated prefix 32a (based on the router advertisement message specifying the DP 32a). The mobile router 12b selects the care-of address 36c, performs a binding update to notify the home agent 14b of the care-of address 36c, and advertises its sub-delegated prefix 32b to the attached nodes 18 which in response establish their own respective care-of addresses 36d and 36e. Also note that the visiting mobile node attached to the mobile router 12b also builds a care-of address 36f (“2:1::9”) based on a router advertisement message from the mobile router 12b that specifies the MNP 24b. However, the prefix delegation by the mobile router 12a in FIG. 2 suffers from the disadvantage that restricting the sub-delegated prefix 32b to within the address space of the delegated prefix 32a of the mobile router 12a limits the flexibility by the mobile router 12b to move within the visited network 42 having the access router 26 as a point of attachment to the Internet 16. In particular, the prefix delegation by the mobile router 12a fails to provide inner mobility in the nested network topology 40 below the mobile router 12a: if any mobile router (e.g., 12a, 12b) changes its point of attachment within the visited network 42 provided by the access router 26, the mobile router must renumber all of its delegated prefixes. Consider the example that mobile router 12b changes its attachment from the mobile router 12a to the access router 26: the mobile router 12b would need to discontinue use of the subdelegated prefix 32b because it conflicts with the delegated prefix 32a assigned to the mobile router 12a. Hence, the mobile router 12b would need to obtain a new delegated prefix (e.g., “3:2::”) from the access router 26. In addition, once the mobile router 12b determined that it was no longer attached to the mobile router 12a, the mobile router 12b would need to advertise its mobile network prefix 24b to maintain connectivity within its mobile network 30b, since the delegated prefixes 32a and 32b were no longer valid (reachable) prefixes. Hence, unknown visiting mobile nodes could build the care-of address 36f based on the MNP 24b, possibly revealing the identity of the mobile router 12b to an unknown visiting mobile node. Moreover, assuming the mobile router 12a changed its attachment from the access router 26 to the mobile router 12b which is now attached to the access router 26, the mobile router 12a would need to discontinue use of its delegated prefix 32a because it is outside the address space of the new delegated prefix (“3:2::”) of the mobile router 12b. Further, the mobile routers 12a and 12b need to repeat the binding updates with their respective home agents 14a and 14b for each attachment because the prior delegated prefixes are no longer usable within the revised network topology. SUMMARY OF THE INVENTION There is a need for an arrangement that enables mobile routers to move transparently within a visited network having an access router configured for assigning delegated prefixes to attached mobile routers, without the necessity of reassignment of address prefixes and resulting binding updates with home agents. There also is a need for an arrangement that enables mobile routers within a visited mobile network to provide added security and anonymity by advertising delegated prefixes to visiting mobile nodes, without the need for advertising their mobile network prefixes that are associated with their respective home networks. These and other needs are attained by the present invention, where an access router of a local mobile network includes a delegation resource for delegating address prefixes and a routing resource configured for parsing reverse routing headers from received data packets. The delegation resource supplies each mobile router attaching to the local mobile network with a corresponding unique delegated address prefix within an available network prefix for use within the local mobile network. Each mobile router attached to the access router via another mobile router utilizes a reverse routing header to establish a tunnel with the access router, enabling the access router to source route messages to the mobile router via its corresponding local care-of address and next-hop addresses specified in the reverse routing header. Each mobile router creates a remote care-of address based on the delegated address prefix, minimizing the need for binding updates with the corresponding home agent as the mobile router moves within the local mobile network. Moreover, the mobile router can advertise the delegated prefix to other mobile nodes, while maintaining confidentiality of its home network prefix, as well as the confidentiality of visiting mobile nodes that attach to the mobile router by using the delegated prefix for a care-of address. One aspect of the present invention provides a method in an access router. The method includes supplying to a first mobile router a delegated address prefix, based on attachment by the first mobile router to one of the access router and a second mobile router attached to the access router. Each mobile router in a local mobile network serviced by the access router receives a corresponding unique delegated address prefix for use within the local mobile network. The method also includes registering a remote care-of address having delegated address prefix with a prescribed home agent of the first mobile router, to register a reachability of the first mobile router. The unique delegated address prefix enables each mobile router to use the delegated address prefix as the mobile router moves through the local mobile network, regardless of whether the mobile router changes its point of attachment. The unique delegated address prefix also enables the access router to establish respective security and traffic policies for the corresponding mobile router. In addition, the registration of the remote care-of address having the delegated address prefix enables the home agent to maintain connectivity with the first mobile router, since the access router will maintain reachability information for the delegated address prefix as the first mobile router moves throughout the local mobile network. Another aspect of the present invention provides a method in a mobile router. The method includes detecting a router advertisement message output by a second mobile router serving as an attachment router for the mobile router. The router advertisement message has a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes. The method also includes generating a local care-of address based on the first network prefix, and outputting a request for a delegated prefix from the access router via the second mobile router. The delegated prefix assigned by the access router is received, wherein the delegated prefix is distinct from the first network prefix. The method also includes advertising the delegated prefix on ingress links of the mobile router. Additional advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the present invention may be realized and attained by means of instrumentalities and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Reference is made to the attached drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein: FIG. 1 is a (PRIOR ART) diagram illustrating a network topology of mobile routers within respective home networks. FIG. 2 is a (PRIOR ART) diagram illustrating a network topology of nested mobile routers with nested prefixes in a visited network. FIGS. 3A and 3B are diagrams illustrating mobile routers having continuous delegated prefixes while moving within a visited network, based on assignment thereof by the access router serving as an attachment point in the visited network, according to an embodiment of the present invention. FIG. 4 is a diagram illustrating in detail the access router of FIGS. 3A and 3B, according to an embodiment of the present invention. FIG. 5 is a diagram illustrating in detail a router advertisement message output by the access router, and an attached mobile router of FIGS. 3A and 3B, according to an embodiment of the present invention. FIG. 6 is a diagram illustrating in detail one of the mobile routers of FIGS. 3A and 3B, according to an embodiment of the present invention. FIG. 7 is a diagram illustrating processing of the reverse routing header by the mobile routers of FIGS. 3A and 3B, according to an embodiment of the present invention. FIGS. 8A and 8B are diagrams illustrating the methods by the access router and the mobile routers of FIGS. 3A and 3B of establishing unique delegated prefixes for each of the mobile routers, according to an embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION FIGS. 3A and 3B are diagrams illustrating network topologies 50, 50′ and 50″ based on an access router (AR) 52 providing connectivity for roaming mobile routers 54a, 54b, and 54c in a local mobile network 56 to a wide area network 16 via a fixed connection 51, according to an embodiment of the present invention. The access router 52 is configured to perform NEMO based operations and as described below. In particular, the access router 52 selects an available network prefix 58 (e.g., “3::”) for use by mobile routers 54a, 54b, and 54c. Note that the access 52 actually may have other network prefixes that it reserves for wired networks, private networks, or the like. The access router 52 outputs a router advertisement message that includes a prefix option that specifies an available network prefix 58 (e.g., “3::”) for the mobile routers 54a, 54b, and 54c to use as a point of attachment, as well as a tree information option. The access router 52 also advertises to the wide area network 16 that the available network prefix 58 having a value of “3::” is globally reachable via the access router 52. The mobile router 54a attaches to the access router 52 based on the advertisement message specifying the available network prefix 58 and the tree information option. In response to the mobile router 54a receiving a delegated prefix 60a (e.g., “3:1::”), the mobile router 54a outputs a router advertisement message specifying a prefix option that specifies the delegated prefix 60a, and a tree information option specifying the tree established by the access router 52 and the relative depth of the tree based on attachment to the mobile router 54a. In response, the mobile router 54b attaches to the mobile router 54a, and obtains its own delegated prefix 60b from the access router 52. FIG. 3A also illustrates a transition 66a in the topology 50 of the local mobile network 56 to the topology 50′ in response to the mobile router 54b attaching from the mobile router 54a to the access router 52. FIG. 3B illustrates a transition 66b in the topology 50′ of the local mobile network 56 to the topology 50″ in response to the mobile router 54a attaching from the access router 52 to the mobile router 54b. As described below, the access router 52 is configured for assigning to each mobile router 54a, 54b, and 54c a corresponding unique delegated address prefix 60a, 60b, and 60c upon initial registration with the access router 52, enabling the mobile routers to move throughout the local mobile network 56 without reassignment of delegated address prefixes. The delegated prefixes 60a, 60b, and 60c are selected from an aggregation of the available network prefix 58 of the access router. Hence, the delegated prefixes 60a, 60b, and 60c having respective values “3:1::”, “3:2::”, and “3:3::” are within the address space of the available network prefix 58 having the value of “3::”. Further, the access router 52 is configured for serving as a Mobile IP home agent that Supports reverse routing header operations, enabling the mobile routers 12a, 12b, and 12c to register their local care-of addresses (LCoA) 62a, 62b, and 62c having values “3::1”, “3:1::1”, and “3:2::4” with the access router 52 using respective tunnels. Each of the tunnels also may have a corresponding security association, enabling the access router 52 and the corresponding mobile router 54a, 54b or 54c to maintain privacy. Note that since the mobile router 54a shares a link with the access router 52 (i.e., is directly connected to the access router 52), use of the reverse routing header is optional, although a tunnel having a security association still may be used. Hence, the access router 52 can maintain a binding cache that specifies, for each mobile router, the delegated network prefix (e.g., 60a, 60b, 60c), the local care-of address (e.g., 62a, 62b, and 62c), and a source-route header that specifies a hop-by-hop path to the corresponding local care-of address. As illustrated in FIGS. 3A and 3B, each mobile router 54a, 54b, and 54c also retains its corresponding original mobile network prefix 24a, 24b, 24c (i.e., native mobile network prefix) having been assigned by its corresponding home agent 63. For example, the mobile router 54a (MR1) and the mobile router 54c (MR3) have respective native mobile network prefixes 24a (“1:1::”) and 24c (“1:2::”) assigned by the home agent 63a (HA1) having the corresponding home prefix 22a (“1::”); themobile router 54b (MR2) has the native mobile network prefixes 24b (“2:1::”) assigned by the home agent 63b (HA2) having the corresponding home prefix 22b (“2::”). However, the assignment of a delegated network prefix (e.g., 60a, 60b, 60c) enables the mobile router (e.g., 54a, 54b, 54c) to establish and maintain a mobile network using its corresponding delegated network prefix (e.g., 60a, 60b, 60c), eliminating the necessity of the mobile router (e.g., 54a, 54b, 54c) advertising its native mobile network prefix (e.g., 24, 24b, 24c). Further, each of the mobile routers 54a, 54b, and 54c are configured for selecting a corresponding home care-of address (also referred to as a remote care-of address (RCoA)) 64a, 64b, and 64c from its corresponding delegated prefix 60a, 60b, and 60c. Once the mobile routers 54a, 54b, and 54c select respective home care-of address 64a, 64b, and 64c, the mobile routers can send binding updates to their respective home agents (e.g., 63a or 63b), specifying that the mobile routers (identifiable by their respective home addresses H1, H2, H3) are reachable via their respective remote care-of addresses 64a, 64b, and 64c. The mobile routers 54a, 54b, and 54c also can send binding update messages specifying that their respective native mobile network prefixes 24a, 24b, and 24c are reachable via the respective remote care-of addresses 64a, 64b, and 64c. The home agent in response updates its binding cache entries to specify that the home addresses (e.g., H1, H2, H3) of the mobile routers 54a, 54b, and 54c, as well as their respective native mobile network prefixes 24a, 24b, and 24c, are reachable via the respective remote care-of addresses 64a, 64b, and 64c within the respective delegated prefixes 60a, 60b, and 60c. Since each delegated prefix is within the available network prefix 58 of the access router 52 that is advertised on the Internet 16, a home agent (e.g., 63a or 63b) can maintain reachability with its mobile router (e.g., 54a, 54b, 54c) via the corresponding home care-of address (64a, 64b, 64c). Hence, the home agent (e.g., 63a or 63b) can forward packets destined to the home addresses (e.g., H1, H2, H3) to the remote care-of addresses 64a, 64b, and 64c via the access router 52. The access router 52 maintains a binding cache of the delegated prefix (e.g., 60a, 60b, 60c) based on the corresponding local care-of address (e.g., 62a, 62b, 62c). Each mobile router (e.g., 54a, 54b, 54c) sends a binding cache update message to the access router in response to establishing a new attachment point in the local mobile network 56, specifying that the mobile router (e.g., 54a, 54b, and 54c) and its corresponding delegated network prefix (e.g., 60a, 60b and 60c) are reachable via the local care-of address (LCoA) (e.g., 62a, 62b, 62′b, 62c in FIG. 3A; 62a, 62′a, 62′b, 62c in FIG. 3B) established based on the new attachment point. Hence, the access router 52 provides reachability for each mobile router (e.g., 54a, 54b, 54c), by forwarding packets received via the Internet 16 and destined either to the mobile router based on its home care-of address (e.g., 64a, 64b, 64c) or destined to its corresponding native mobile network prefix (e.g., 24a, 24b, 24c), based on updating its binding cache entries specifying the local care-of addresses (e.g., 62a, 62b, 62c). For example, FIG. 3A illustrates that the mobile router 54b moves from the mobile router 54a and attaches directly to the access router 52, resulting in the topology 50′. The mobile router 54b attaches to the access router 52 by creating a new care-of address 62′b, having a value of “3::2”, based on detecting a router advertisement message from the access router 52 that specifies the available network prefix 58 “3::”. The mobile router 54b sends a binding update message to the access router 52 to notify the access router 52 of the new local care-of address 62′b that supersedes the original care-of address 62b. However, the remote care-of address 64b is unchanged because the mobile router 54b continues to use its delegated address prefix 60b. Similarly, FIG. 3B illustrates that the mobile router 54a moves from the access router 52 and attaches to the mobile router 54b, resulting in the topology 50″. The mobile router 54a attaches to the mobile router 54b by creating a new care-of address 62′a, having a value of “3:2::2”, based on detecting a router advertisement message from the mobile router 54b that specifies the delegated network prefix 60b available from the mobile router 54b is “3:2::”. The mobile router 54a sends a binding update message to the access router 52 to notify the access router 52 of the new local care-of address 62′a that supersedes the original care-of address 62a. However, the remote care-of address 64a is unchanged because the mobile router 54a continues to use its delegated address prefix 60a. Hence, the necessity for sending binding updates to the home agent (e.g., 63a or 63b) for registration of a remote care-of address (e.g., 64a, 64b, 64c) for a corresponding a mobile router (e.g., 54a, 54b, and 54c), needs only be performed once for the duration that the mobile router is roaming within the local mobile network 56, regardless of whether changes in the topology are encountered as illustrated in FIGS. 3A and 3B. FIG. 4 is a block diagram illustrating the access router 52, according to an embodiment of the present invention. The access router 52 includes a DHCPv6 delegation resource 70 configured for delegating prefixes as described in the above-incorporated Internet Draft by Troan et al. As described below, the delegation resource 70 is configured for supplying to each mobile router (e.g., 54a, 54b, 54c) a corresponding delegated address prefix (e.g., 60a, 60b, and 60c), wherein each of the delegated address prefixes (e.g., 60a, 60b, and 60c) are within the address space of the available network prefix 58, enabling the delegated address prefixes to be used throughout the local mobile network 56. The access router 52 also includes a routing resource 72 that includes a router advertisement resource 74, a routing table 76, and a reverse routing header (RRH) resource 70. The routing table is configured for storing a plurality of binding cache entries 80. Each binding cache entry (e.g., 80a, 80b, 80c) is configured for storing the corresponding local care-of address (e.g., 62a, 62b, 62c) for a corresponding delegated address prefix (e.g., 60a, 60b, and 60c), or the corresponding mobile router (e.g., 54a, 54b, 54c). It is apparent, however, that separate entries may be stored for each mobile router and each delegated prefix 80, depending on implementation of the routing table 76. The reverse routing header resource 78 is configured for providing reverse routing header functionality, and serving as a tunnel endpoint to terminate a tunnel with a mobile router, as described in the above incorporated Thubert-RRH Internet Draft. In particular, the reverse routing header resource 78 is configured for establishing a source route for reaching a corresponding local care-of address 62 based on successive next-hop addresses specified within the reverse routing header of the received message. The reverse routing header is described below with respect to FIG. 7. FIG. 5 is a diagram illustrating the router advertisement message 82 output by the router advertisement resource 74, according to an embodiment of the present invention. The router advertisement message 82 includes a mandatory router advertisement portion 84 in accordance with RFC 2461, entitled “Neighbor Discovery for IP Version 6 (IPv6)”, available on the IETF website at http://www.ietf.org/rfc/rfc2461.txt and incorporated in its entirety herein by reference. The router advertisement message 82 also includes a prefix option portion 86 in accordance with Section 4.6.2 of RFC 2461, and a tree information option portion 88 in accordance with the above-incorporated Thubert-RRH Internet Draft. The prefix option portion 86 includes an option type field 90a (“3”), a prefix length field 92 that specifies the valid length of the available prefix 58, and a prefix value 94 having a 128-bit IPv6 address, of which the most significant bits as specified in the prefix length field 92 are valid. The tree information option field 88 is used to identify characteristics of the tree formed by the access router 52 acting as a top level mobile router. In particular, the tree information option field 88 includes an option type field 90b (“10”), a preference field 95 specifying a prescribed preference value for the corresponding tree, a depth field 96 specifying the number of hops to the top-level mobile router (TLMR) specified in the TLMR field 97, a tree group field 98, and flag bits 100a, 100b, and 100c. The TLMR field 97 specifies the global IPv6 address of the router (e.g., 52, 54a, 54b, 54c) transmitting the router advertisement message 82. The tree group field 98 specifies an IPv6 global address (set by the TLMR 52) that is used to identify the tree (e.g, the network topology 50 includes a single tree based on the sequential connection of routers 54c to 54b to 54a to 53). The flag bit 100a (F=1) is used to specify that the access router 52 is a fixed mobile router. The flag bit 100b (H=1) is used to specify that the access router 52 acts as a home agent, and the flag bit 100a (D=1) is used to specify that the access router 52 is configured to operate as a delegating router (DR) configured for performing prefix delegation (PD) according to DHCPv6 protocol. Hence, the access router 52 advertises itself as a DHCPv6 delegating router for prefix delegation (DHCPv6-PD DR). FIG. 6 is a diagram illustrating the mobile router 54, according to an embodiment of the present invention. The mobile router 54 includes an egress interface 140, an ingress interface 142, and a routing resource 144 that includes a router advertisement resource 74 and a mobility (NEMO) resource 146. The ingress interface 142 is configured for receiving data traffic from attached nodes, and forwarding the traffic to the Internet 16 via the egress interface 140, based on attachment to the access router 52 and any other intermediate routers. The ingress interface 142 also is configured for outputting router advertisement messages 82 generated by the router advertisement resource 74. The mobility resource 146 includes a care of address generation resource 148, a reverse routing header resource 78, and a DHCPv6 compliant prefix request resource 150, that serves as a DHCPv6 client that interacts with the DHCPv6 delegation resource 70 according to RFC 3633. Additional details will be described below. FIG. 7 is a diagram illustrating a reverse routing header generated by the RRH resource 78 in the mobile routers, in accordance with the above-incorporated Thubert-RRH draft. In particular, FIG. 7 illustrates updating of a reverse routing header 190a, 190b, and 190c by the originating mobile router 54c, the intermediate mobile router 54b, and the mobile router 54a, respectively, having the topology 50. In particular, FIG. 7 illustrates a packet 101 having a source address field 102, a destination address field 104, extended headers 106, a reverse routing header (e.g., 190a) and an inner packet 108 (e.g., a request for a delegated address prefix) having been generated by an originating source, for example the mobile router 54c As described in the above incorporated Thubert-RRH, the mobile router 54c, as the originating mobile router, outputs the packet 101 having the source address field 102 specifying the care of address 112c (MR3LCoA) of the mobile router 54c, and a selected number of empty address slots 114 within the reverse routing header 190a. The empty slots enable the routers 54b and 54a to store their respective care of addresses within the lPv6 header (e.g., within the reverse routing header or the source address field 102). In particular, the RRH resource 78 of the mobile router 54c the resource 43 inserts a prescribed home address 116 (MR3_HAddr) (or an alias for anonymous connections) for the mobile router 54c in the first slot (slot0), and specifies a routing header of type “4” within a type field 118. The RRH resource 78 inserts the care of address 112c of the mobile router 54c in the source address field 102, and the address 120 (AR) of the corresponding access router 52 in the destination address field 104, and outputs the packet 101 to its attachment router 54b. The mobile router 54b, in response to detecting the reverse routing header 190a, selectively updates the reverse routing header by inserting the source address value 112c into the detected empty entry field “slot1”, resulting in the updated reverse routing header 190b. The mobile router 54b inserts its own care of address 112b into the source address field 102, and outputs the packet to its attachment router 54a. The mobile router 54a, in response to detecting the reverse routing header 190b, selectively updates the reverse routing header by inserting the source address value 112b into the detected empty entry field “slot2”, resulting in the updated reverse routing header 190c. The mobile router 54a inserts its own care of address 112a into the source address field 102, and outputs the packet to the access router 52. Hence, the reverse routing header provides a tunnel between the originating mobile router (e.g., 54c) and the access router 52. The access router 52 reads the bottom entry 116 to identify the home address of the mobile router 54c, using the entry as if it was a mobile IPv6 home address destination option (i.e., as an index into the binding cache). The access router 52 now can send a packet directly back via the tunnel by using the reverse routing header 190c and the source address 102 in building the source routing header. FIGS. 8A and 8B are diagrams illustrating delegation of address prefix is by the access router 52 to the mobile routers 54, according to an embodiment of the present invention. The steps described herein with respect to FIGS. 8A and 8B can be implemented in the respective mobile nodes as executable code stored on a computer readable medium (e.g., floppy disk, hard disk, EEPROM, CD-ROM, etc.), or propagated via a computer readable transmission medium (e.g., fiber optic cable, electrically-conductive transmission line medium, wireless electromagnetic medium, etc.). The method begins in step 200, where the router advertisement resource 74 of the access router 52 outputs a router advertisement message including a prefix option 86 specifying the available network prefix (P) 58 having a value of “3::” and a tree information option 88 specifying that the access router 52 is a NEMO capable fixed top level mobile router (TLMR) capable of prefix delegation. In response to detecting the router advertisement message, the mobile router 54aattaches in step 202 to the access router 52 by configuring its local care of address 62a based on the advertised prefix 58, sending a request to the access router 52 for a delegated prefix (DPI) 60a, and upon receipt thereof, advertising the delegated prefix 60a on its ingress port 142. In particular, the router advertisement message 82 output by the mobile router 54a specifies the delegated prefix 60a in the prefix portion 94 of the prefix option 86, with the appropriate prefix length specified in the length field 92; the tree information option 88 is identical to the tree information option output by the access router 52, except that the mobile router 54a increments the depth field 96 by “1” indicating the mobile router 54a is one hop away from the TLMR. As described above, the mobile router 54a does not need to the utilize a reverse routing header because it is directly attached to the access router 52. The mobile router 54a also sends a binding update to its home agent 63a (HA1) specifying that the mobile router 54a (identifiable by its home address H1) and/or its corresponding native mobile network prefix 24a (“1:1::”) is reachable via the remote care-of address 64a (3:1::1”). The routing resource 144 of the mobile router 54b detects in step 204 the router advertisement message 82 received by the egress interface 140 from the mobile router 54a, which specifies the delegated prefix 60a, and the tree information options 88. In response to detecting the tree information option 88, the mobility resource 146 parses the tree information option 88 in step 206, and detects that the bit 100c is set indicating that the access router 52, as the top-level mobile router, is configured as a delegating router. In response the care of address generation resource 148 causes the mobile router 54b to the attached to the mobile router 54a in step 208 by building a local care of address 62b based on the delegated prefix 60a (DP1). The mobile router 54b generates a packet in step 210. The packet includes the DHCPv6 request 108 generated by the request resource 150, and the reverse routing header 190 generated by the RRH resource 78. The routing resource 72 adds its local care of address 62b within the source address field 102, and the address 120 of the access router 52 in the destination address field 104, which was retrieved by the mobility resource 146 from the TLMR identifier 97 in the tree information option field 88. The delegation resource 70 in the access router 52 receives in step 212 the delegated prefix request and the attached RRH 190. The delegation resource 70 in response assigns in step 214 the delegated prefix 60b (DP2) and updates its binding cache entry 80b to specify that the delegated prefix 60b and the mobile router 54b are reachable via the local care of address 62b; the routing resource 72 also stores the reverse routing header in the form of the source router entry for the local care of address 62b, specifying that the local care of address 62b is reachable via the source route generated from the reverse routing header. The delegation resource 70 sends in step 216 the delegated prefix 60b to the mobile router 54b using the source route obtained from the reverse routing header. In response to the DHCPv6 client 150 receiving the delegated prefix 60b, the care of address generation resource 148 selects in step 218 a remote care of address (R-CoA) 64b that is within the address space of the delegated prefix 60b. The router advertisement resource 74 in the mobile router 54b advertises in step 220 the delegated prefix 60b on its ingress interface 142. The mobility resource 146 of the mobile router 54b uses its internal binding update resource (not shown) to send a binding update with a reverse routing header to its home agent 63b (HA2) in step 222, specifying that the mobile router 54b (identifiable by its home address H2) and/or its corresponding native mobile network prefix 24b (MNP2) having a value of “2:1::” is reachable via the remote care of address 64b. The reverse routing header 78 of the access router 52 terminates the tunnel in step 224 by stripping the reverse routing header fields 190, storing the source route back to the originating mobile router 54b relative to its care of address value 62b specified in the reverse routing header; the access router 52 adds its own address in the source address field 102, and forwards in step 226 the binding update message to the home agent 63b. FIG. 8B is a diagram illustrating the transition 66a and FIG. 3A, where the mobile router 54b attaches directly to the access router 52. The mobile router 54b detects in step 230 the router advertisement message 82 from the access router 52 specifying the prefix (P) 58, and the tree information options 88. The mobility resource 146 detects in step 232 that the access router 52 is a top-level mobile router, and that the flag bit 100c is set indicating that the access router 52 is a delegating router. The care of address generation resource 148 in the mobile router 54b attaches to the access router 52 in step 234 by generating a new care of address 62′b (“3::2”) that is within the address space of the available network prefix 58 advertised by the access router 52. The mobility resource 146 of the mobile router 54b generates a binding update message for the access router 52 in step 236 that specifies the new local care of address 62′b. In response to the routing resource 72 in the access router 52 receiving the binding update message in step 238, the routing resource 72 updates in step 240 the binding cache entry 80b to specify that the mobile router 54b and the delegated prefix 60b are reachable via the new local care of address 62′b having a value of “3::2”. The routing resource 72 cents a binding acknowledgment back to the mobile router 54b in step 242. According to the disclosed embodiment, NEMO route optimization can be applied to roaming mobile routers in a visited network, while conforming to Basic Nemo protocols outside of the nested structure. In addition, since a mobile router need only advertise the delegated prefix in the clear, privacy can be maintained regarding keeping its home address prefix secret to untrusted access routers or visiting mobile nodes. Hence, the mobile router and the access router (and local mobile nodes) can be anonymous to each other upon implementation of RFC 3041 in each node. Also, the access router may place the mobile router traffic in specific categories so the visited access router can enforce its own security and prevent the visiting mobile router from over utilizing its resources. Finally, the long distance registration to the home agent is preserved while the mobile router moves within the local mobile network of the access router, which allows the access router to limit access. Note that use of reverse routing headers optimizes communications by eliminating nested tunnels between a mobile router and the access router; however, use of reverse routing headers may be omitted at the expense of utilizing nested tunnels. In addition, it should be readily apparent that the disclosed embodiment is applicable to any number of mobile routers that may attach to the attachment router. While the disclosed embodiment has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to route optimization by a mobile router of a mobile network, for example a mobile IP network (NEMO) or an Internet Protocol (IP) based mobile ad hoc network (MANET), and an access router providing an attachment point to a wide area network such as the Internet. 2. Description of the Related Art Proposals have been made by Internet Engineering Task Force (IETF) groups for improved mobility support of Internet Protocol (IP) based mobile devices (e.g., laptops, IP phones, personal digital assistants, etc.) in an effort to provide continuous Internet Protocol (IP) based connectivity. The IETF has two working groups focusing on mobile networks, a Mobile Ad-hoc Networks (MANET) Working Group that is working to develop standardized MANET routing specification(s) for adoption by the IETF, and NEMO (mobile networks). NEMO uses Mobile IP (MIP) to provide connectivity between mobile networks and the infrastructure (e.g., the Internet). The key component in NEMO is a mobile router that handles MIP on behalf of the mobile networks that it serves. A “Mobile IPv6” protocol is disclosed in an Internet Draft by Johnson et al., entitled “Mobility Support in IPv6”, available on the World Wide Web at the address: http://www.ietf.org/internet-drafts/draft-ietf-mobileip-ipv6-24.txt (the disclosure of which is incorporated in its entirety herein by reference). According to Johnson et al., the Mobile IPv6 protocol enables a mobile node to move from one link to another without changing the mobile node's IP address. In particular, the mobile node is assigned a “home address”. The “home address” is an IP address assigned to the mobile node within its home subnet prefix on its home link. While a mobile node is at home, packets addressed to its home address are routed to the mobile node's home link, using conventional Internet routing mechanisms. The mobile node also is assigned a home agent for registering any care-of address used by the mobile node at its point of attachment to the Internet while the mobile node is away from its home link. A care-of address is an IP address associated with a mobile node that has the subnet prefix of a particular link away from its home link (i.e., a foreign link). A home agent is a router on a mobile node's home link with which the mobile node has registered its current care-of address. While the mobile node is away from its home link, the home agent intercepts packets on the home link destined to the mobile node's home address; the home agent encapsulates the packets, and tunnels the packets to the mobile node's registered care-of address. The NEMO working group has extended the features of Mobile IPv6 (which to date have been limited to an IPv6 mobile node such as a wireless laptop) to a mobile network based on providing routing protocols that enable the mobile router to attach to an access router and establish route optimization for the mobile router and its associated mobile network. One example of proposed solutions for route optimization in a nested mobile network is disclosed in the Internet Draft by Thubert et al., “Taxonomy of Route Optimization models in the Nemo Context”, available on the IETF website at http://www.ietf.org/internet-drafts/draft-thubert-nemo-ro-taxonomy-02.txt and the disclosure of which is incorporated in its entirety herein by reference (referred to hereinafter as “Thubert-RO”). In particular, Thubert-RO notes that NEMO enables Mobile Networks by extending Mobile IP to support Mobile Routers; Thubert-RO describes how Route Optimization as described in the context of MIPv6 can to be adapted for NEMO to optimize traffic routing between nodes in a mobile network and their correspondent nodes. Another example of a proposed solution for route optimization is disclosed in the Internet Draft by Thubert et al., “IPv6 Reverse Routing Header and its application to Mobile Networks” available on the IETF website at http://www.ietf.org/internet-drafts/draft-thubert-nemo-reverse-routing-header-04.txt and the disclosure of which is incorporated in its entirety herein by reference (referred to hereinafter as “Thubert-RRH”). Thubert-RRH discloses that Mobile IP can be extended to support mobile routers, and enable nested mobile networks, using a reverse routing header that eliminates the need for nested tunnels between mobile routers and their home agents, but rather enables use of a single tunnel between a mobile router and its associated home agent. One particular aspect of the above proposals is that the mobile router communicates with its associated home agent to ensure reachability between the mobile router and the wide area packet switched network (e.g., the Internet). It may be desirable in certain cases to reduce the necessity for a mobile router to establish a tunnel with its associated home agent in order to have connectivity with the wide area packet switched network. For example, it may be desirable in certain cases that a mobile router can establish anonymous route connections without notifying the home agent of the source of the route connections. It also may be desirable in certain cases that a mobile router can establish multiple attachments with different access routers as the mobile router moves (i.e., “roams”) across the respective service of the access routers, without the necessity of notifying the home agent of each attachment, especially when the attachment may be for only a transient interval. Other proposals attempt to minimize nesting of tunnels, as well as avoid a tunnel between a mobile router and its corresponding home agent, by adding prescribed operations to a top level mobile router of a mobile network. One example is described in the Internet Draft by Kang et al., “Route Optimization for Mobile Network by Using Bi-directional Between Home Agent and Top Level Mobile Router”, available on the World Wide Web at http://www.watersprings.org/pub/id/draft-hkang-nemo-ro-tlmr-00.txt and incorporated in its entirety herein by reference. Another example of minimizing nesting of tunnels and avoiding a tunnel between a mobile router and its corresponding home agent involves use of a mobility anchor point (MAP). A variation of the Mobile IPv6 protocol is disclosed in an IETF Internet Draft by Soliman et al., “Hierarchical Mobile IPv6 mobility management (HMIPv6)” June 2003, available on the World Wide Web at http://www.ietf.org/internet-drafts/draft-ietf-mobileip-hmipv6-08.txt and incorporated in its entirety herein by reference. The Internet Draft by Soliman et al. discloses a Mobility Anchor Point (MAP) within an IPv6 network that implements HMIPv6 by assigning a regional care-of address to mobile nodes within its address realm. Mobile nodes may thus use on-link care-of addresses for communications within the address realm of the MAP, and the regional care-of address for lPv6 communications outside the MAP address realm. As such, the MAP serves as a local home agent. Hence, a mobile node is always addressable by its “home address”: packets may be routed to the mobile node using this address regardless of the mobile node's current point of attachment to the Internet. The mobile node also may continue to communicate with other nodes (stationary or mobile) after moving to a new link. The movement of a mobile node away from its home link is thus transparent to transport and higher-layer protocols and applications. As apparent from the foregoing, however, Soliman et al. is limited to mobile nodes, and does not describe use of HMIP for a mobile router in a manner that could be applied to a mobile network served by the mobile router. However, route optimization has been described in the Internet Draft by Ohnishi et al., “HMlP based Route Optimization Method in a Mobile Network” available at the IETF website at http://www.ietf.org/intemet-drafts/draft-ohnishi-nemo-ro-hmip-00.txt and the disclosure of which is incorporated in its entirety herein by reference. Of particular interest is a proposal that describes using prefix delegation, such as Dynamic Host Configuration Protocol (DHCP): DHCP is described in Droms et al., “Dynamic Host Configuration Protocol for IPv6 (DHCPv6)”, published by the IETF as a Request for Comments (RFC) 3315 and available on the World Wide Web at http://www.ietf.org/rfc/rfc3315.txt (the disclosure of which is incorporated in its entirety herein by reference). Prefix delegation in DHCP is described in Troan et al., “IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6”, published by the IETF as RFC 3633 and available at the IETF website at http://www.ietf.org/rfc/rfc3633:.txt (the disclosure of which is incorporated in its entirety herein by reference). In particular, the Internet Draft by Lee et al., “Route Optimization for Mobile Nodes in Mobile Network based on Prefix Delegation”, available at the IETF website at http://www.ietf.org/internet-drafts/draft-leekj-nemo-ro-pd-02.txt (the disclosure of which is incorporated in its entirety herein by reference) discloses an access router that delegates a prefix to a top level mobile router. FIGS. 1 and 2 are diagrams from the above-incorporated Internet Draft by Lee et al. FIG. IIlustrates a network 10 having mobile routers 12 a and 12 b attached to their respective home agents 14 a and 14 b . The home agents 14 a and 14 b each provide a point of attachment in FIG. 1 between the respective mobile routers 12 a and 12 b and the Internet 16 , enabling the mobile nodes 18 to communicate with a correspondent node 20 . Each of the home agents 14 a and 14 b has a corresponding home address prefix: the home agent “HA-MR1” 14 a has a home address prefix 22 a of “1::”, and the home agent “HA-MR2” 14 b has a home address prefix 22 b of “2::”, according to the IPv6 addressing convention specified in RFC 3513, available on the Internet at http://www.ietf.org/rfc/rfc3513.txt (the disclosure of which is incorporated in its entirety herein by reference). Hence, the mobile routers “MR1” 12 a and “MR2” 12 b are assigned by their respective home agents 14 a and 14 b the mobile network prefixes 24 a and 24 b having respective values “1:1::” and “2:1::”. Consequently, the mobile routers 12 a and 12 b advertise their respective mobile network prefixes 24 a and 24 b to their respective attached nodes 18 and consequently form mobile networks 30 a and 30 b . FIG. 1 also illustrates an access router 26 having a corresponding local network 42 , also referred to herein as a visited network, having a network prefix 28 with a value of “3::”. FIG. 2 illustrates a revised network topology 10 ′ based on the movement of the mobile routers 12 a and 12 b from their respective home agents 14 a and 14 b and attachment with the access router 26 . As shown in FIG. 2 , each mobile router (e.g., 12 a and 12 b ) has a home address (HoA) (e.g., 34 a , 34 b ) based on its corresponding home address prefix (e.g., 22 a , 22 b ): the home address 34 a of the mobile router (MR 1 ) 12 a has a value of “1::1” within the address space of the home address prefix 22 a “1::”, and the home address 34 b of the mobile router (MR 2 ) 12 b has a value of “2::3” within the address space of the home address prefix 22 b “ 2::”. According to the Internet Draft by Lee et al., the mobile router 12 a detects movement and obtains a delegated prefix (DP) 32 a having a value of “3:1::” from the access router 26 according to a prefix delegation protocol such as DHCPv6. The detection of movement by the mobile router 12 a is based on, for example, a detected loss of connectivity with the home agent 14 a , detecting router advertisement messages from the access router 26 , and attaching to the access router 26 . In response to receiving the delegated prefix 32 a , the mobile router 12 a builds a care-of address (CoA) 36 a within the network prefix 28 , and performs a binding update with its home agent 14 a to enable the home agent 14 a to identify that the home address 34 a of the mobile router 12 a is reachable via the care-of address 36 a. In response to assignment of the delegated prefix 32 a , the mobile router 12 a also outputs router advertisement messages that advertise the delegated prefix 32 a , using a prescribed Delegated Prefix option. Note that the mobile router 12 a also outputs router advertisement messages that advertise its mobile network prefix 24 a . The second mobile router (MR 2 ) 12 b in response attaches to the mobile router 12 a , and obtains from the mobile router 12 a a sub-delegated prefix 32 b having a value of “3:1:1::” and that is within the address space of the delegated prefix 32 a “3:1::” assigned to the mobile router 12 a. The mobile router 12 b , having attached to the mobile router 12 a , obtains a care-of address (CoA 2 ) 36 b based on the mobile network prefix 24 a (based on the router advertisement message specifying the MNP 24 a ) and a care-of address (CoA 1 ) 36 c based on the delegated prefix 32 a (based on the router advertisement message specifying the DP 32 a ). The mobile router 12 b selects the care-of address 36 c , performs a binding update to notify the home agent 14 b of the care-of address 36 c , and advertises its sub-delegated prefix 32 b to the attached nodes 18 which in response establish their own respective care-of addresses 36 d and 36 e . Also note that the visiting mobile node attached to the mobile router 12 b also builds a care-of address 36 f (“2:1::9”) based on a router advertisement message from the mobile router 12 b that specifies the MNP 24 b. However, the prefix delegation by the mobile router 12 a in FIG. 2 suffers from the disadvantage that restricting the sub-delegated prefix 32 b to within the address space of the delegated prefix 32 a of the mobile router 12 a limits the flexibility by the mobile router 12 b to move within the visited network 42 having the access router 26 as a point of attachment to the Internet 16 . In particular, the prefix delegation by the mobile router 12 a fails to provide inner mobility in the nested network topology 40 below the mobile router 12 a : if any mobile router (e.g., 12 a , 12 b ) changes its point of attachment within the visited network 42 provided by the access router 26 , the mobile router must renumber all of its delegated prefixes. Consider the example that mobile router 12 b changes its attachment from the mobile router 12 a to the access router 26 : the mobile router 12 b would need to discontinue use of the subdelegated prefix 32 b because it conflicts with the delegated prefix 32 a assigned to the mobile router 12 a . Hence, the mobile router 12 b would need to obtain a new delegated prefix (e.g., “3:2::”) from the access router 26 . In addition, once the mobile router 12 b determined that it was no longer attached to the mobile router 12 a , the mobile router 12 b would need to advertise its mobile network prefix 24 b to maintain connectivity within its mobile network 30 b , since the delegated prefixes 32 a and 32 b were no longer valid (reachable) prefixes. Hence, unknown visiting mobile nodes could build the care-of address 36 f based on the MNP 24 b , possibly revealing the identity of the mobile router 12 b to an unknown visiting mobile node. Moreover, assuming the mobile router 12 a changed its attachment from the access router 26 to the mobile router 12 b which is now attached to the access router 26 , the mobile router 12 a would need to discontinue use of its delegated prefix 32 a because it is outside the address space of the new delegated prefix (“3:2::”) of the mobile router 12 b. Further, the mobile routers 12 a and 12 b need to repeat the binding updates with their respective home agents 14 a and 14 b for each attachment because the prior delegated prefixes are no longer usable within the revised network topology. | <SOH> SUMMARY OF THE INVENTION <EOH>There is a need for an arrangement that enables mobile routers to move transparently within a visited network having an access router configured for assigning delegated prefixes to attached mobile routers, without the necessity of reassignment of address prefixes and resulting binding updates with home agents. There also is a need for an arrangement that enables mobile routers within a visited mobile network to provide added security and anonymity by advertising delegated prefixes to visiting mobile nodes, without the need for advertising their mobile network prefixes that are associated with their respective home networks. These and other needs are attained by the present invention, where an access router of a local mobile network includes a delegation resource for delegating address prefixes and a routing resource configured for parsing reverse routing headers from received data packets. The delegation resource supplies each mobile router attaching to the local mobile network with a corresponding unique delegated address prefix within an available network prefix for use within the local mobile network. Each mobile router attached to the access router via another mobile router utilizes a reverse routing header to establish a tunnel with the access router, enabling the access router to source route messages to the mobile router via its corresponding local care-of address and next-hop addresses specified in the reverse routing header. Each mobile router creates a remote care-of address based on the delegated address prefix, minimizing the need for binding updates with the corresponding home agent as the mobile router moves within the local mobile network. Moreover, the mobile router can advertise the delegated prefix to other mobile nodes, while maintaining confidentiality of its home network prefix, as well as the confidentiality of visiting mobile nodes that attach to the mobile router by using the delegated prefix for a care-of address. One aspect of the present invention provides a method in an access router. The method includes supplying to a first mobile router a delegated address prefix, based on attachment by the first mobile router to one of the access router and a second mobile router attached to the access router. Each mobile router in a local mobile network serviced by the access router receives a corresponding unique delegated address prefix for use within the local mobile network. The method also includes registering a remote care-of address having delegated address prefix with a prescribed home agent of the first mobile router, to register a reachability of the first mobile router. The unique delegated address prefix enables each mobile router to use the delegated address prefix as the mobile router moves through the local mobile network, regardless of whether the mobile router changes its point of attachment. The unique delegated address prefix also enables the access router to establish respective security and traffic policies for the corresponding mobile router. In addition, the registration of the remote care-of address having the delegated address prefix enables the home agent to maintain connectivity with the first mobile router, since the access router will maintain reachability information for the delegated address prefix as the first mobile router moves throughout the local mobile network. Another aspect of the present invention provides a method in a mobile router. The method includes detecting a router advertisement message output by a second mobile router serving as an attachment router for the mobile router. The router advertisement message has a prefix option and a tree information option, the prefix option specifying a first network prefix for use within a local mobile network serviced by the second mobile router, the tree information option specifying an access router as a top level router and that is configured as a delegating router for supplying delegated address prefixes. The method also includes generating a local care-of address based on the first network prefix, and outputting a request for a delegated prefix from the access router via the second mobile router. The delegated prefix assigned by the access router is received, wherein the delegated prefix is distinct from the first network prefix. The method also includes advertising the delegated prefix on ingress links of the mobile router. Additional advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the present invention may be realized and attained by means of instrumentalities and combinations particularly pointed out in the appended claims. | 20040323 | 20060502 | 20050512 | 59376.0 | 0 | PHUNKULH, BOB A | ARRANGEMENT IN AN ACCESS ROUTER FOR OPTIMIZING MOBILE ROUTER CONNECTIONS BASED ON DELEGATED NETWORK PREFIXES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,806,575 | ACCEPTED | Automatic update of squelch tables for optical network applications | A method and system for processing a squelch table for optical network applications. The method includes receiving a first cross-connection entry associated with a first cross-connection and a first channel, and generating a first squelch entry associated with the first channel in a first squelch table associated with a first node. Additionally, the method includes sending a first request message associated with the first cross-connection to a second node. Moreover, the method includes if a first response message associated with the first cross-connection is received at the first node in response to the first request message within a predetermined period of time, processing information associated with the first response message and modifying the first squelch entry in response to at least information associated with the first response message. | 1. A method for processing a squelch table for optical network applications, the method comprising: receiving a first cross-connection entry associated with a first cross-connection and a first channel; generating a first squelch entry associated with the first channel in a first squelch table associated with a first node, the first squelch table free from any squelch entry associated with the first channel other than the first squelch entry; sending a first request message associated with the first cross-connection to a second node, the second node being a neighboring node to the first node; if a first response message associated with the first cross-connection is received at the first node in response to the first request message within a predetermined period of time, processing information associated with the first response message; modifying the first squelch entry in response to at least information associated with the first response message. 2. The method of claim 1 wherein the first request message comprises a source node identification field associated with a source node related to the first cross-connection and a destination node identification field associated with a destination node related to the first cross-connection. 3. The method of claim 2 wherein the first request message further comprises a message identification field associated with a message identification. 4. The method of claim 3 wherein the message identification is related to at least one selected from a group consisting of AD, DR, DA, DD, NO, and NS. 5. The method of claim 3 wherein the first request message further comprises a request/response field indicating the first request message being a request. 6. The method of claim 5 wherein the first request message further comprises a direction field associated with a direction related to the first request message, wherein the direction is west or east. 7. The method of claim 6 wherein the first request message further comprises a channel indicator associated with a channel identification corresponding to the first squelch table. 8. The method of claim 7 wherein the first request message further comprises a VT indicator associated with a VT identification corresponding to the first squelch table. 9. The method of claim 1 wherein the first channel is a STS channel or a VT channel. 10. The method of claim 1 wherein the modified first squelch entry comprises complete squelch information associated with the first cross-connection. 11. The method of claim 1, and further comprising: if the first response message is not received at the first node within the predetermined period of time and the first request message is sent for more than a predetermined number of times, sending a first alarm message indicating a failure to receive the first response message; if the first response message is not received at the first node within the predetermined period of time and the first request message is sent for less than or equal to a predetermined number of times, sending the first request message to the second node. 12. The method of claim 11, and further comprising: processing information associated with a first ring map related to the first node; determining whether the first ring map is complete based on at least information associated with the first ring map. 13. The method of claim 12, and further comprising: providing a first indication associated with the generating a first squelch entry; providing a second indication associated with the generating a first squelch entry. 14. A method for processing a squelch table for optical network applications, the method comprising: receiving a first request message associated with a first cross-connection and a first channel; processing information associated with the first request message and a first squelch table at a first node; determining whether the first squelch table includes a first squelch entry associated with the first channel; if the first squelch table is free from the first squelch entry, sending a first response message; if the first squelch table includes the first squelch entry, processing information associated with the first request message; modifying the first squelch entry in response to at least information associated with the first request message; sending a second response message associated with the first cross-connection. 15. The method of claim 14 wherein the first response message is associated with NO cross-connection. 16. The method of claim 14 wherein the second response message comprises a source node identification field associated with a source node related to the first cross-connection and a destination node identification field associated with a destination node related to the first cross-connection. 17. The method of claim 16 wherein the second response message further comprises a message identification field associated with a message identification. 18. The method of claim 17 wherein the message identification is related to at least one selected from a group consisting of AD, DR, DA, DD, NO, and NS. 19. The method of claim 17 wherein the second response message further comprises a request/response field indicating the second response message being a response. 20. The method of claim 19 wherein the second response message further comprises a direction field associated with a direction related to the second response message, wherein the direction is west or east. 21. The method of claim 20 wherein the second response message further comprises a channel indicator associated with a channel identification corresponding to the first squelch table. 22. The method of claim 21 wherein the first request message further comprises a VT indicator associated with a VT identification corresponding to the first squelch table. 23. The method of claim 14 wherein the first channel is a STS channel or a VT channel. 24. An apparatus for processing a squelch table for optical network applications, the apparatus comprising: a message receiver configured to receive a first request message associated with a first cross-connection and a first channel; receive a first response message associated with a second cross-connection and a second channel; a message sender configured to send a first request message associated with the second cross-connection and the second channel; send a first response message associated with the first cross-connection and the first channel; a memory system configured to store at least information associated with a first squelch table; a processing system coupled to the message receiver, the message sender, and the memory system and is configured to generate a first squelch entry associated with the second channel in the first squelch table, the first squelch table free from any squelch entry associated with the second channel other than the first squelch entry; process information associated with the first response message; modify the first squelch entry in response to at least information associated with the first response message; process information associated with the first request message and the first squelch table; determine whether the first squelch table includes a second squelch entry associated with the first channel; process information associated with the first request message; modify the second squelch entry in response to at least information associated with the first request message. 25. The method of claim 24 wherein the first channel is a STS channel or a VT channel. 26. The method of claim 24 wherein the first channel and the second channel are the same channel. 27. The method of claim 24 wherein the first channel and the second channel are different channels. | CROSS-REFERENCES TO RELATED APPLICATIONS Not Applicable STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK. Not Applicable COPYRIGHT NOTICE A portion of this application contains computer codes, which are owned by FutureWei Technologies, Inc. All rights have been preserved under the copyright protection, FutureWei Technologies, Inc. ©2004. BACKGROUND OF THE INVENTION The present invention relates in general to telecommunication techniques. More particularly, the invention provides a method and system including a squelch table update technique for optical networks. Merely by way of example, the invention is described as it applies to Bi-directional Line-Switched Ring (BLSR) in Synchronous Optical Network (SONET), but it should be recognized that the invention has a broader range of applicability. Telecommunication techniques have progressed through the years. As merely an example, Synchronous Optical Network (SONET) has been used for conventional optical telecommunications for telephone applications. SONET defines a technique for transmitting multiple signals of different capacities through a synchronous, flexible, optical hierarchy. The SONET can terminate signals, multiplex signals from a lower speed to a higher speed, switch signals, and transport signals in the network according to certain definitions. Multiple SONET nodes may be interconnected into a ring structure to achieve high survivability. For example, if the SONET suffers from a connection failure at one location, the SONET can intelligently send the affected signals through one or more alternative routes without encountering the failure location. Such rerouting process is often known as automatic protection switching (APS). A Bi-directional Line-Switched Ring (BLSR) is a ring, which uses the SONET line-level status and performance parameters to initiate the APS process. In a BLSR, a terminal is often called a node. The terminal is assigned to a node ID. The node ID identifies the SONET terminal within the BLSR. The Node IDs on a BLSR may not have consecutive values; hence the value of a Node ID usually does not imply any connectivity information but is merely the identification for a node in the ring. To represent the physical connectivity, a ring map contains a complete order of Node IDs. The ring map is usually available at each node along with a squelch table. A squelch table includes a topological map of traffic at a specified node. For each STS channel that is terminated or passed through the specified node, the squelch table usually contains the source node ID of the incoming Synchronous Transport Signal (STS) channel and the destination node ID of the outgoing STS channel. The squelch table can be used to prevent traffic misconnection in case of node failure or ring segmentation of BLSR. The squelching may be performed at the STS level or at the Virtual Tributary (VT) level. From time to time, the squelch table at each node needs to be updated either manually or automatically. For example, when a node is removed from the ring or added to the ring, the squelch table should be updated. Some conventional protocols have been implemented to automatically update the squelch table. These conventional protocols, however, usually involve complicated mechanisms. It may take a long time to update the squelch table. Additionally, a large amount of traffic may be generated by these protocols which can lead to limited bandwidth being available for other management functions. Other limitations also exist with conventional BLSR techniques. Hence it is highly desirable to improve squelch table update techniques for optical networks. BRIEF SUMMARY OF THE INVENTION The present invention relates in general to telecommunication techniques. More particularly, the invention provides a method and system including a squelch table update technique for optical networks. Merely by way of example, the invention is described as it applies to Bi-directional Line-Switched Ring (BLSR) in Synchronous Optical Network (SONET), but it should be recognized that the invention has a broader range of applicability. According to one embodiment of the present invention, a method for processing a squelch table for optical network applications includes receiving a first cross-connection entry associated with a first cross-connection and a first channel, and generating a first squelch entry associated with the first channel in a first squelch table associated with a first node. The first squelch table is free from any squelch entry associated with the first channel other than the first squelch entry. Additionally, the method includes sending a first request message associated with the first cross-connection to a second node. The second node is a neighboring node to the first node. Moreover, the method includes if a first response message associated with the first cross-connection is received at the first node in response to the first request message within a predetermined period of time, processing information associated with the first response message and modifying the first squelch entry in response to at least information associated with the first response message. According to yet another embodiment of the present invention, a method for processing a squelch table for optical network applications includes receiving a first request message associated with a first cross-connection and a first channel, processing information associated with the first request message and a first squelch table at a first node, and determining whether the first squelch table includes a first squelch entry associated with the first channel. Additionally, the method includes if the first squelch table is free from the first squelch entry sending a first response message, and if the first squelch table includes the first squelch entry processing information associated with the first request message. Moreover, the method includes modifying the first squelch entry in response to at least information associated with the first request message and sending a second response message associated with the first cross-connection. According to yet another embodiment of the present invention, an apparatus for processing a squelch table for optical network applications includes a message receiver configured to receive a first request message associated with a first cross-connection and a first channel and receive a first response message associated with a second cross-connection and a second channel. Additionally, the apparatus includes a message sender configured to send a first request message associated with the second cross-connection and the second channel and send a first response message associated with the first cross-connection and the first channel. Moreover, the apparatus includes a memory system configured to store at least information associated with a first squelch table. Also, the apparatus includes a processing system coupled to the message receiver, the message sender, and the memory system. The processing system is configured to generate a first squelch entry associated with the second channel in the first squelch table, the first squelch table free from any squelch entry associated with the second channel other than the first squelch entry, process information associated with the first response message, and modify the first squelch entry in response to at least information associated with the first response message. The processing system is also configured to process information associated with the first request message and the first squelch table, determine whether the first squelch table includes a second squelch entry associated with the first channel, process information associated with the first request message, and modify the second squelch entry in response to at least information associated with the first request message. Many benefits are achieved by way of the present invention over conventional techniques. For example, certain embodiments of the present invention operate in either manual mode or automatic mode selectively for every network node or every network ring. The internal messaging enables the network nodes on a network ring to simultaneously enter manual mode or automatic mode. Some embodiments of the present invention provide support for STS-level squelching, VT-level squelching, or both. Any mismatch of cross-connection types can be identified by certain protocols in the present invention. Certain embodiments of the present invention provides an alarm indication if any entry in the cross-connection table does not have a corresponding entry in the squelch table. Some embodiments of the present invention can initiate an update of a squelch table at any time for any specific node. Certain embodiments of the present invention can initialize a squelch table by restore the backup table from memory. Some embodiments of the present invention can perform automatic update of squelch table even under single ring failure conditions. Certain embodiments of the present invention provide an appropriate designation to indicate that a time slot is unassigned or does not have a cross-connection. Some embodiments of the present invention can allow for the in-service change of Node ID of a network node without causing a flood of messages to readjust the squelch tables. Certain embodiments of the present invention can detect mismatches in payloads through the protocol and help in diagnostic issues regarding squelching and provisioning of cross-connections. Some embodiments of the present invention have the flexibility to transmit protocol messages over the overhead SONET bytes or the DCC channels. Certain embodiments of the present invention use only 32 bits to communicate a squelch entry data to the neighboring node. Some embodiments of the present invention can transport information unrelated to squelching over a BLSR ring. Certain embodiments of the present invention use scalable and expandable protocol to cope with various BLSR rates for both STS and VT level squelching. For example, the BLSR rates may be those of OC-48, OC-192 and OC-768 Various additional objects, features and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawings that follow. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified diagram for protocol message according to one embodiment of the present invention; FIG. 2 is a simplified method for automatically updating squelch table according to an embodiment of the present invention; FIGS. 2A-2J are simplified methods for automatically updating squelch table according to certain embodiments of the present invention; FIG. 3 illustrates simplified cross-connections between two network nodes according to one embodiment of the present invention; FIG. 4 is a simplified method for implementing cross-connections in squelch tables according to an embodiment of the present invention; FIG. 5 is a simplified apparatus for automatically updating squelch table according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates in general to telecommunication techniques. More particularly, the invention provides a method and system including a squelch table update technique for optical networks. Merely by way of example, the invention is described as it applies to Bi-directional Line-Switched Ring (BLSR) in Synchronous Optical Network (SONET), but it should be recognized that the invention has a broader range of applicability. FIG. 1 is a simplified diagram for protocol message according to one embodiment of the present invention. The diagram is merely an example, which should not unduly limit the scope of the present invention. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. In FIG. 1, a protocol message 100 includes a message ID field 110, a request/response field 120, a east/west field 130, a channel ID field 140, a source node ID field 150, a destination node ID field 160, and a spare field 170. Although the above has been shown using message fields 110, 120, 130, 140, 150, 160, and 170, there can be many alternatives, modifications, and variations. For example, the number of bits in each field may vary depending upon specific applications of the present invention. Some of the message fields may be combined. Other fields may be added to the protocol message. Depending upon the embodiment, one or more of the message fields may be removed. For example, the spare field 170 may be removed. Further details of these processes are found throughout the present specification and more particularly below. The protocol message 100 contains information about changes of squelch table at a node from which the protocol message is sent. The protocol message 100 traverses from a sending node to its adjacent nodes through communication interfaces or an overhead channel. The protocol message 100 may support the squelching at STS level, VT level, or both. Additionally, the protocol message 100 may take the form of Protocol Data Unit (PDU). The message ID field 110 contains information about the type of change to the squelch table at the sending node. The type of change may include one of the following: Add (AD), Drop (DR), Drop and Continue (DR&PTIN), Pass-Thru-In (PTIN), Pass-Thru-Out (PTOUT), Delete Add (DA), Delete Drop (DD), Delete Pass-Thru-Out (DPTOUT), Delete Pass-Thru-In (DPTIN), Delete Drop and Continue (DDR&PTIN), No Cross-Connection (NO), and Non-Squelch message (NS). NS indicates that a non-squelch-table type message is being sent for communicating alarm or other message information between nodes. These types of changes may correspond to the same message ID or different message IDs. The message IDs are represented by three-bit codes as shown in Table 1. For example, both AD and POUT types of changes correspond to message ID AD and code 111. Additionally, codes 010 and 001 are not yet used and may carry other information. TABLE 1 Types of Changes Message IDs Codes AD/PTOUT AD 111 DR/PTIN/DR&PTIN DR 110 DA/DPTOUT DA 101 DD/DPTIN/DDR&PTIN DD 100 NO NO 011 NS NS 000 Not Used 010 Not Used 001 As discussed above and further emphasized here, Table 1 is merely an example, which should not unduly limit the scope of the present invention. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. For example, the message ID field may take more than three bits and assign each type of change a distinct message ID and a distinct code. As another example, the message ID field may take less than three bits and assign the same code to several types of changes. The field 120 specifies whether the protocol message 100 is a request for information from the sending node or a response to such a request. For example, the field 120 assigns code 1 to request and code 0 to response. As another example, the field 120 takes up more than one bit. For requests, the message ID may be AD, DR, DA, DD, or NS. For Responses, the message ID may be AD, DR, NO, or NS. The field 130 specifies the traveling direction of the protocol message 100. For example, the field 130 assigns 1 to the East direction and assigns 0 to the West direction. The request message travels in a direction opposite to the corresponding response message. For example, if a request message travels in the East direction, the response message should travel in the West direction. When the protocol message 100 cannot traverse in the intended direction, the protocol message 100 may be rerouted to the other direction. The intermediate nodes would pass through this message based on the inconsistency between the direction indicated in the field 130 and the direction in which the message in fact travels. The field 140 specifies the STS channel number corresponding to the processed squelch table. For example, the field 140 takes up 10 bits and accommodate an OC768 4-Fiber BLSR ring. The field 150 contains information related to the source node ID of a traffic connection. For example, the field 150 is five-bit long, among which four bits provide the source node ID. The fifth bit indicates whether the protocol message 100 contains a valid source node ID. For certain message ID such as PT, the source Node ID is unknown. Hence if the fifth bit is set to 1, the source node ID in the other four bits are ignored. The field 160 contains information related to the destination node ID of a traffic connection. For example, the field 150 is five-bit long, among which four bits provide the destination node ID. The fifth bit indicates whether the protocol message 100 contains a valid destination node ID. For certain message ID such as PT, the destination Node ID is unknown. Hence if the fifth bit is set to 1, the destination node ID in the other four bits are ignored. The messages for DR, PTIN and DR&PTIN have the same message ID but different destination node IDs. Whenever there is a PTIN connection, the node sending the protocol message is not the destination node and the destination node ID does not equal the node ID sending the message. If the destination drop cross-connection is not provisioned, the destination node ID is ignored as indicated by the 5th bit of the field 160. The field 170 may contain optional information. For example, the field 170 may provide a VT identification for VT squelching and indicate VT-Access capability. As another example, the field 170 provides an indication of STS path concatenation level. As yet another example, the field 170 provides a check-sum to check the data contained in the protocol message 100. The check sum is for example useful when the squelch tables are updated using hardware logic and the protocol message is transported over Line/Section layer overhead bytes. As yet another example, the field 170 carries any information unrelated to squelching. FIG. 2 is a simplified method for automatically updating squelch table according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. The method 200 includes a process 210 for starting system, a process 220 for checking completion of ring map, a process 230 for receiving new entry, a process 240 for adding new entry to squelch table, a process 250 for setting indicator and sending request message, a process 260 for checking timeliness of response message, a process 270 for updating squelch table and resetting indicator, a process 280 for repeating request message, a process 290 for receiving request message, a process 292 for checking existence of entry, a process 294 for sending response message, a process 296 for updating squelch table, and a process 298 for sending response message. Although the above has been shown using a selected sequence of processes, there can be many alternatives, modifications, and variations. For example, some of the processes may be expanded and/or combined. Other processes may be inserted to those noted above. Depending upon the embodiment, the specific sequence of processes may be interchanged with others replaced. For example, the process 210 for starting system is skipped. As another example, the process 220 for checking completion of ring map is skipped. Further details of these processes are found throughout the present specification and more particularly below. At the process 210, the hardware and software system is started at a network node. The process 210 can be skipped if the hardware and software system is already running. At the process 220, the completion of a ring map is verified. For example, a ring map stored at the network node contains a complete order of Node IDs in a BLSR ring. If the ring map is not completed, the process 220 would be repeated. If the ring map is completed, the process 230 is performed or the process 290 is performed. In another example, both processes 230 and 290 are performed. At the process 230, a new cross-connection entry is received at the network node. For example, the new entry is a provision or a deletion of one of following cross-connections: AD, DR, DR&PTIN, PTIN, PTOUT, DA, DD, DPTOUT, DPTIN, or DDR&PTIN. The new entry corresponds to a specific STS channel or a VT channel. For the STS or VT channel, the squelch table does not have a pre-existing entry. At the process 240, the new cross-connection entry is added to a squelch table at the network node. If the new entry is a provision of a cross-connection, the cross-connection is entered into the squelch table. If the new entry is a deletion of a cross-connection, the cross-connection is deleted from the squelch table. When a squelch table does not contain a specific cross-connection, or a valid source node ID or a destination node ID for the specific cross-connection, the entry associated with the specific cross-connection is not available when the user retrieves the squelch table. Consequently, the squelch entry does not exist for the associated STS or VT. At the process 250, an indicator is set to show the cross-section entry entered into the squelch table is new. For example, the indicator is a flag in a software program related to the squelch table. Additionally, a request message is sent from the network node. For example, the request message may be the protocol message 100 requesting information. In another example, the intended recipient of the request message is one or both neighboring nodes of the sending node in a BLSR ring. The request message may be carried over the fixed overhead on the SONET line or section, such as unused D-bytes. In another example, the request message is carried over the section or line DCC channels, in which case the proper DCC associations should be established for the request message. Also at the process 250, a response clock is started to measure the time period from sending the request message to receiving a response message. As discussed above and further emphasized here, there can be many alternatives, modifications, and variations. For example, one or two of the above three processes, i.e., setting indicator, sending request message and starting clock, are skipped. At the process 260, whether a response message is timely received is checked. If a response message is received within a predetermined time period based on measurements of the response clock, the response message is considered timely. If the response message is not received within the predetermined time period, the process 280 is performed. For example, the response message is received from a network node receiving the request message sent in the process 250. At the process 270, the squelch table is updated using the information from the response message. For example, the information in the response message is translated corresponding to the new entry in the squelch table. The translation to the new entry can be performed with software or hardware. For example, an FPGA system extracts the information in the response message carried over the overhead. Additionally, the indicator is reset to show that the cross-connection is old. At the process 280, a request message is resent if the request message has not been resent for over a predetermined number of times. Subsequently the process 260 is repeated. If the request message has been sent for over a predetermined number of times, an alarm message indicating response failure is sent to the management system. For example, the management system facilitates the operation of a BLSR ring. The alarm message indicates a squelch table response processing failure. At the process 290, a request message for a cross-connection is received. The cross-connection may be added, deleted, or edited. For example, the request message may be the protocol message 100 requesting information. In another example, the sender of the request message is a neighboring node of the receiving node in a BLSR ring. At the process 292, the existence of the cross-connection in the squelch table is checked. If the squelch table at the receiving node contains the cross-connection, the process 294 is performed. If the squelch table at the receiving node does not contain the cross-connection, the processes 296 and 298 are performed. At the process 294, a response message is sent to the node sending the request message. For example, the request message may be the protocol message 100 with the message ID field indicating No Cross-Connection (NO). The response message may be carried over the fixed overhead on the SONET line or section, such as unused D-bytes. In another example, the response message is carried over the section or line DCC channels, in which case the proper DCC associations should be established for the response message. At the process 296, the squelch table at the receiving node is updated based on information in the request message. At the process 298, a response message is sent to the node sending the request message. The response message contains information about the cross-connection related to the request message. The information may enable the node sending the request message to update its squelch table. As discussed above and further emphasized here, FIG. 2 is merely an example. For example, the method 200 may be modified according to FIGS. 2A through 2J. FIGS. 2A-2J are simplified methods for automatically updating squelch table according to certain embodiments of the present invention. These diagram are merely examples, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. In FIGS. 2A-2J, “SRC” represents source node ID, “DST” represents destination node ID, “Node ID” represents the node ID of the network node to whose squelch table AD, DR, or PT is being added, “X” represents unknown, “E” represents east side of the network node, and “W” represents west side of the network node. “PT” includes both PTIN and PTOUT. FIGS. 2A, 2B and 2C describe methods for adding cross-connections AD, DR and PT respectively. Each cross-connection undergoes a validation process by checking whether the cross-connection is allowed in the cross-connection table. If the cross-connection is not allowed, an alarm message indicating invalid cross-connection is sent to the management system. If the cross-connection is allowed, the mode of operation is determined. If the mode of operation is manual, the automatic update stops. If the mode of operation is automatic, the automatic update continues. Next, whether an entry already exists is checked for the STS or VT to which AD, DR, or PT is being added. If the entry does not exist, an entry is created in the squelch table. A request message is sent or the automatic update is completed. If the entry already exists, the type of the existing entry is determined. If the existing entry corresponds to NO at E or NO at W, the entry is updated and a request message is sent. If the existing entry corresponds to NO at both E and W, the entry is updated. If the existing entry corresponds to a cross-connection other than NO and the cross-connection being added, an alarm message indicating invalid entry is sent to the management system. If the existing entry corresponds to a cross-connection being added, the automatic update completes. FIGS. 2D, 2E and 2F describe methods for deleting cross-connections AD, DR and PT respectively. PT includes PTIN and PTOUT. Each cross-connection undergoes a validation process by checking whether the cross-connection is allowed in the cross-connection table. If the cross-connection is not allowed, an alarm message indicating invalid cross-connection is sent to the management system. If the cross-connection is allowed, the mode of operation is determined. If the mode of operation is manual, the automatic update stops. If the mode of operation is automatic, the automatic update continues. Next, whether an entry already exists is checked for the STS or VT from which AD, DR, or PT is being deleted. If the entry does not exist, the automatic update is completed. If the entry already exists, the type of the existing entry is determined. If the existing entry corresponds to NO or a cross-connection being deleted, the squelch table is updated. The request message is sent, or the automatic update is completed. If the existing entry corresponds to a cross-connection other than NO and the cross-connection being deleted, an alarm message indicating invalid entry is sent to the management system. In FIGS. 2D, 2E and 2F, the validity of the source node ID or the destination node ID may be determined by the fifth bit as described for the fields 150 and 160 in FIG. 1. FIGS. 2G and 2H describe methods for processing request message for adding cross-connections AD and DR respectively. For example, the request message is sent from the East side of the network node where the request message is originated. Whether the request message is received at the West side is then determined. If the request message is not received at the West side, the request message is passed through to the next node until the neighboring node on the East side of the originating or destination node is reached. If the neighboring node has been reached or the request message is received at the West side, the mode of operation is determined. If the mode of operation is manual, the automatic update stops. If the mode of operation is automatic, the automatic update continues. Next, whether an entry already exists is checked for the STS or VT to which AD or DR is being added. If the entry does not exist, an entry for NO cross-connection is created with either the source node ID or the destination node ID specified. A response message is sent from the West side. If the entry already exists, the type of the existing entry is determined. If the existing entry corresponds to the cross-connection being added, an alarm message indicating invalid entry is sent to the management system. If the existing entry corresponds to a PT cross-connection, both the entries for the East side and the West side are updated, and a request message is each sent from the East side and the West side. If the existing entry corresponds to a NO cross-section or a cross-section other than PT and the cross-connection being added, the entry on the West side is updated and a response message is sent from the West side. FIGS. 2I and 2J describe methods for processing request message for deleting cross-connections AD and DR respectively. For example, the request message is sent from the East side of the network node where the request message is originated. Whether the request message is received at the West side is then determined. If the request message is not received at the West side, the request message is passed through to the next node until the neighboring node on the East side of the originating or destination node is reached. If the neighboring node has been reached or the request message is received at the West side, the mode of operation is determined. If the mode of operation is manual, the automatic update stops. If the mode of operation is automatic, the automatic update continues. Next, whether an entry already exists is checked for the STS or VT from which AD or DR is being deleted. If the entry does not exist, a response message is sent from the West side. If the entry already exists, the type of the existing entry is determined. If the existing entry corresponds to AD or DR in FIG. 2I or 2J respectively, an alarm message indicating invalid request is sent to the management system. If the existing entry corresponds to a PT cross-connection, both the entries for the East side and the West side are updated, and a request message is each sent from the East side and the West side. If the existing entry corresponds to a NO cross-section or a cross-section other than PT and AD or DR in FIG. 2I or 2J respectively, the entry on the West side is updated and a response message is sent from the West side. As discussed above and further emphasized here, FIGS. 2 and 2A-2J are merely examples, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. For example, the methods of FIGS. 2 and 2A-2J can update and/or create a squelch table. In another example, the method 200 can update a preexisting entry in a squelch table or create a new entry in the squelch table. Each network node generates its squelch table by sending request messages and receiving response messages for each cross-connection added to or removed from the squelch table. For example, this process is usually performed for all new cross-connections when a network node is initialized or at system start-up. In another example, the process modifies the squelch tables in the neighboring nodes, which in turn send messages to their neighbors until all the squelch tables in the BLSR ring are updated. In yet another example, at node initialization the squelch tables are restored from non-volatile memory. The following is an exemplary memory record of a squelch table: class CSquelchTbRecord { private: //BIT6-7:represent the incoming cross-connect type: NO/ /DR/PTIN/DR&PTIN //BIT5:represent whether the response PDU is received. //BIT0-4:represent the incoming SRC node ID (BIT4 =1 if the SRC is unknown) BYTE m_byIncoming; //BIT6-7:represent the outgoing cross-connect type: NO//AD/PTOUT //BIT5:represent whether the response PDU is received. //BIT0-4:represent the outgoing DST node ID (BIT 4 =1 if the DST is unknown) BYTE m_byOutgoing; BOOL m_bSrcVtAccess; //Reserved for future if support vt squelch BOOL m_bDstVtAccess; //Reserved for future if support vt squelch void *m_pVtAccess; //Reserved for future if support Vt squelch ... }; CSquelchTbRecord m_SquelchTb1 [2][192]; //Squelch Table It is important to fast update squelch tables. For example, the hardware processing of protocol messages may achieve a response time of less than 10 ms from the adjacent network node. For a BLSR ring of 16 nodes, the update time could last for 160 ms. If the DCC channels are used, the update may take much longer than 160 ms. The DCC is common medium that carries traffic messages for different applications. To shorten the update time, certain mechanisms can be implemented to advance the priority of the protocol messages with respect to other messages over the DCC channels. FIG. 3 illustrates simplified cross-connections between two network nodes according to one embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. The cross-connections 300 go through nodes 310, 320 and 330 representing nodes A, B and C respectively. The cross-connections 300 include adding a signal to the node 310, passing through the signal into a West terminal 322 of the node 320, passing through the signal out of the East terminal 324 of the node 320, and dropping the signal at the node 330. Although the above has been shown using a selected sequence of unidirectional cross-connections, there can be many alternatives, modifications, and variations. For example, some of the cross-connections may be expanded and/or combined. Other processes may be inserted to those noted above. Depending upon the embodiment, the specific sequence of cross-connections may be interchanged with others replaced. Further details of these processes are found throughout the present specification and more particularly below. The cross-sections illustrated in FIG. 3 are summarized in Table 2. As shown in Table 2, Node A adds a new entry for AD, Node B adds a new entry for PTOUT at East and a new entry for PTIN at West, and Node C adds a new entry for DR in their respective squelch table. TABLE 2 East West out in out in DR PTIN DR&PTIN AD PTOUT DR PTIN DR&PTIN AD PTOUT A ✓ B ✓ ✓ C ✓ FIG. 4 is a simplified method for implementing cross-connections in squelch tables according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. For example, the method 400 uses the method 200 as discussed above. Node A adds an AD entry to its squelch table. It is assumed that the entry has a source node ID of Node A. Node A sends a request message 410 to Node B. For example, the request message 410 takes the same for mat as the protocol message 100. The message ID field is set to AD, the request/response field is set to request, the east/west field is set to east, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to unknown. The spare field may contain additional information. Node B receives the request message 410 and edit its squelch table. The entry for PT on both west and east sides are updated by setting the source node to Node A. Additionally, Node B sends a response message 420 to Node A. For example, the response message 420 takes the same format as the protocol message 100. The message ID field is set to PTIN, the request/response field is set to response, the east/west field is set to west, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to unknown. The spare field may contain additional information. Also, Node B sends a request message 424 to Node C. For example, the request message 424 takes the same format as the protocol message 100. The message ID field is set to PTOUT, the request/response field is set to request, the east/west field is set to east, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to unknown. The spare field may contain additional information. Node C receives the request message 424 and edits its squelch table. The entry for DR is assumed to have a source node ID of Node A. Additionally, Node B sends a response message 430 to Node B. For example, the response message 420 takes the same format as the protocol message 100. The message ID field is set to DR, the request/response field is set to response, the east/west field is set to west, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to A. The spare field may contain additional information. Also, Node C sends a request message 434 to Node B. For example, the request message 434 takes the same format as the protocol message 100. The message ID field is set to DR, the request/response field is set to request, the east/west field is set to west, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to C. The spare field may contain additional information. Node B receives the request message 434 and edit its squelch table. The entry for PT on both west and east sides are updated by setting the destination node to Node C. Additionally, Node B sends a response message 440 to Node C. For example, the response message 440 takes the same format as the protocol message 100. The message ID field is set to PTOUT, the request/response field is set to response, the east/west field is set to east, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to C. The spare field may contain additional information. Also, Node B sends a request message 444 to Node A. For example, the request message 444 takes the same format as the protocol message 100. The message ID field is set to PTIN, the request/response field is set to request, the east/west field is set to west, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to Node C. The spare field may contain additional information. Node A receives the request message 444 and edit its squelch table. The entry for AD are updated by setting the destination node to Node C. Additionally, Node B sends a response message 500 to Node B. For example, the response message 500 takes the same format as the protocol message 100. The message ID field is set to AD, the request/response field is set to response, the east/west field is set to east, the channel ID field is set to channel 1, the source node ID field is set of Node A, and the destination node ID field is set to C. The spare field may contain additional information. After the message exchange and processing are completed, the squelch table entries for Nodes A, B and C are shown in Table 3. “Src” represents source node ID, “Dest” represents destination node ID. TABLE 3 East West Incoming Outgoing Incoming Outgoing Node Src Vt-acc Vt-acc Dest Src Vt-acc Vt-acc Dest A x C B x C A x C A x As discussed above and further emphasized here, FIG. 4 is merely an example, which should not unduly limit the scope of the present invention. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. For example, the message ID fields for the messages 420 and 444 are changed to DR, and the message ID fields for the messages 430 and 434 are changed to PTIN. In another example, the message ID fields for the messages 424 and 440 are changed to AD, and the message ID fields for the messages 410 and 450 are changed to PTOUT. FIG. 5 is a simplified apparatus for automatically updating squelch table according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. The apparatus 500 includes a message receiver 510, a message sender 520, a memory system 530, and a processing system 540. Although the above has been shown using the systems 510, 520, 530, and 540, there can be many alternatives, modifications, and variations. For example, the memory system 530 and the processing system 540 may be combined. The processing system 540 may be expanded to include its own memory system. Other systems may be added to those noted above. Depending upon the embodiment, the specific arrangement of systems may be interchanged with others replaced. Further details of these systems found throughout the present specification and more particularly below. The message receiver 510 receives a request message and/or a response message, the message sender 520 sends a request message and/or a response message, and the memory system 530 stores a squelch table and/or a cross-connection table. The processing system 540 processes the received request message and/or the received response message, and generates the sent request message and/or the sent response message. Additionally, the processing system processes information related to any cross-connection entry and information associated with the squelch table and/or the cross-connection table. For example, each node of a BLSR has an apparatus substantially similar to the apparatus 500. The message receiver 510 is configured to receive some or all messages related to FIGS. 1, 2, 2A-2J, 3, and 4. The message sender 520 is configured to send some or all messages related to FIGS. 1, 2, 2A-2J, 3, and 4. The processing system 540 is configured to perform some or all processes related to FIGS. 1, 2, 2A-2J, 3, and 4. These processes may be performed with software, hardware, or combination thereof. According to another embodiment of the present invention, an apparatus for processing a squelch table for optical network applications includes a message receiver configured to receive a first request message associated with a first cross-connection and a first channel and receive a first response message associated with a second cross-connection and a second channel. Additionally, the apparatus includes a message sender configured to send a first request message associated with the second cross-connection and the second channel and send a first response message associated with the first cross-connection and the first channel. Moreover, the apparatus includes a memory system configured to store at least information associated with a first squelch table. Also, the apparatus includes a processing system coupled to the message receiver, the message sender, and the memory system. The processing system is configured to generate a first squelch entry associated with the second channel in the first squelch table, the first squelch table free from any squelch entry associated with the second channel other than the first squelch entry, process information associated with the first response message, and modify the first squelch entry in response to at least information associated with the first response message. The processing system is also configured to process information associated with the first request message and the first squelch table, determine whether the first squelch table includes a second squelch entry associated with the first channel, process information associated with the first request message, and modify the second squelch entry in response to at least information associated with the first request message. As discussed above, certain embodiments of the present invention can generate some or all of the following alarm messages. Invalid cross-connection message indicates the user enters an invalid cross-connection, e.g. DR on the outgoing channel. Invalid entry message indicates detection of an invalid squelch table entry, e.g. AD on an incoming channel. Invalid request message indicates inconsistent received request message, e.g., when an DA message is received by a node that has and AD entry on the same channel. A response failure message indicates a response to a request is not received within a predetermined period times for over a predetermined number of times. Inconsistent squelch message indicates inconsistent squelch tables when cross-connection table entries do not reflect squelch table entries. Incomplete update message indicates. an update to squelch table at a node is not complete. The present invention has various advantages. Certain embodiments of the present invention operate in either manual mode or automatic mode selectively for every network node or every network ring. The internal messaging enables the network nodes on a network ring to simultaneously enter manual mode or automatic mode. Some embodiments of the present invention provide support for STS-level squelching, VT-level squelching, or both. Any mismatch of cross-connection types can be identified by certain protocols in the present invention. Certain embodiments of the present invention provides an alarm indication if any entry in the cross-connection table does not have a corresponding entry in the squelch table. Some embodiments of the present invention can initiate an update of a squelch table at any time for any specific node. Certain embodiments of the present invention can initialize a squelch table by restore the backup table from memory. Some embodiments of the present invention can perform automatic update of squelch table even under single ring failure conditions. Certain embodiments of the present invention provide an appropriate designation to indicate that a time slot is unassigned or does not have a cross-connection. Some embodiments of the present invention can allow for the in-service change of Node ID of a network node without causing a flood of messages to readjust the squelch tables. Certain embodiments of the present invention can detect mismatches in payloads through the protocol and help in diagnostic issues regarding squelching and provisioning of cross-connections. Some embodiments of the present invention have the flexibility to transmit protocol messages over the overhead SONET bytes or the DCC channels. Certain embodiments of the present invention use only 32 bits to communicate a squelch entry data to the neighboring node. Some embodiments of the present invention can transport information unrelated to squelching over a BLSR ring. Certain embodiments of the present invention use scalable and expandable protocol to cope with various BLSR rates for both STS and VT level squelching. For example, the BLSR rates may be those of OC-48, OC-192 and OC-768. Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims. For example, certain embodiments of the present invention may be used in SONET or any other network. As another example, some embodiments of the present invention may be used in a BLSR ring or any other network ring. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates in general to telecommunication techniques. More particularly, the invention provides a method and system including a squelch table update technique for optical networks. Merely by way of example, the invention is described as it applies to Bi-directional Line-Switched Ring (BLSR) in Synchronous Optical Network (SONET), but it should be recognized that the invention has a broader range of applicability. Telecommunication techniques have progressed through the years. As merely an example, Synchronous Optical Network (SONET) has been used for conventional optical telecommunications for telephone applications. SONET defines a technique for transmitting multiple signals of different capacities through a synchronous, flexible, optical hierarchy. The SONET can terminate signals, multiplex signals from a lower speed to a higher speed, switch signals, and transport signals in the network according to certain definitions. Multiple SONET nodes may be interconnected into a ring structure to achieve high survivability. For example, if the SONET suffers from a connection failure at one location, the SONET can intelligently send the affected signals through one or more alternative routes without encountering the failure location. Such rerouting process is often known as automatic protection switching (APS). A Bi-directional Line-Switched Ring (BLSR) is a ring, which uses the SONET line-level status and performance parameters to initiate the APS process. In a BLSR, a terminal is often called a node. The terminal is assigned to a node ID. The node ID identifies the SONET terminal within the BLSR. The Node IDs on a BLSR may not have consecutive values; hence the value of a Node ID usually does not imply any connectivity information but is merely the identification for a node in the ring. To represent the physical connectivity, a ring map contains a complete order of Node IDs. The ring map is usually available at each node along with a squelch table. A squelch table includes a topological map of traffic at a specified node. For each STS channel that is terminated or passed through the specified node, the squelch table usually contains the source node ID of the incoming Synchronous Transport Signal (STS) channel and the destination node ID of the outgoing STS channel. The squelch table can be used to prevent traffic misconnection in case of node failure or ring segmentation of BLSR. The squelching may be performed at the STS level or at the Virtual Tributary (VT) level. From time to time, the squelch table at each node needs to be updated either manually or automatically. For example, when a node is removed from the ring or added to the ring, the squelch table should be updated. Some conventional protocols have been implemented to automatically update the squelch table. These conventional protocols, however, usually involve complicated mechanisms. It may take a long time to update the squelch table. Additionally, a large amount of traffic may be generated by these protocols which can lead to limited bandwidth being available for other management functions. Other limitations also exist with conventional BLSR techniques. Hence it is highly desirable to improve squelch table update techniques for optical networks. | <SOH> BRIEF SUMMARY OF THE INVENTION <EOH>The present invention relates in general to telecommunication techniques. More particularly, the invention provides a method and system including a squelch table update technique for optical networks. Merely by way of example, the invention is described as it applies to Bi-directional Line-Switched Ring (BLSR) in Synchronous Optical Network (SONET), but it should be recognized that the invention has a broader range of applicability. According to one embodiment of the present invention, a method for processing a squelch table for optical network applications includes receiving a first cross-connection entry associated with a first cross-connection and a first channel, and generating a first squelch entry associated with the first channel in a first squelch table associated with a first node. The first squelch table is free from any squelch entry associated with the first channel other than the first squelch entry. Additionally, the method includes sending a first request message associated with the first cross-connection to a second node. The second node is a neighboring node to the first node. Moreover, the method includes if a first response message associated with the first cross-connection is received at the first node in response to the first request message within a predetermined period of time, processing information associated with the first response message and modifying the first squelch entry in response to at least information associated with the first response message. According to yet another embodiment of the present invention, a method for processing a squelch table for optical network applications includes receiving a first request message associated with a first cross-connection and a first channel, processing information associated with the first request message and a first squelch table at a first node, and determining whether the first squelch table includes a first squelch entry associated with the first channel. Additionally, the method includes if the first squelch table is free from the first squelch entry sending a first response message, and if the first squelch table includes the first squelch entry processing information associated with the first request message. Moreover, the method includes modifying the first squelch entry in response to at least information associated with the first request message and sending a second response message associated with the first cross-connection. According to yet another embodiment of the present invention, an apparatus for processing a squelch table for optical network applications includes a message receiver configured to receive a first request message associated with a first cross-connection and a first channel and receive a first response message associated with a second cross-connection and a second channel. Additionally, the apparatus includes a message sender configured to send a first request message associated with the second cross-connection and the second channel and send a first response message associated with the first cross-connection and the first channel. Moreover, the apparatus includes a memory system configured to store at least information associated with a first squelch table. Also, the apparatus includes a processing system coupled to the message receiver, the message sender, and the memory system. The processing system is configured to generate a first squelch entry associated with the second channel in the first squelch table, the first squelch table free from any squelch entry associated with the second channel other than the first squelch entry, process information associated with the first response message, and modify the first squelch entry in response to at least information associated with the first response message. The processing system is also configured to process information associated with the first request message and the first squelch table, determine whether the first squelch table includes a second squelch entry associated with the first channel, process information associated with the first request message, and modify the second squelch entry in response to at least information associated with the first request message. Many benefits are achieved by way of the present invention over conventional techniques. For example, certain embodiments of the present invention operate in either manual mode or automatic mode selectively for every network node or every network ring. The internal messaging enables the network nodes on a network ring to simultaneously enter manual mode or automatic mode. Some embodiments of the present invention provide support for STS-level squelching, VT-level squelching, or both. Any mismatch of cross-connection types can be identified by certain protocols in the present invention. Certain embodiments of the present invention provides an alarm indication if any entry in the cross-connection table does not have a corresponding entry in the squelch table. Some embodiments of the present invention can initiate an update of a squelch table at any time for any specific node. Certain embodiments of the present invention can initialize a squelch table by restore the backup table from memory. Some embodiments of the present invention can perform automatic update of squelch table even under single ring failure conditions. Certain embodiments of the present invention provide an appropriate designation to indicate that a time slot is unassigned or does not have a cross-connection. Some embodiments of the present invention can allow for the in-service change of Node ID of a network node without causing a flood of messages to readjust the squelch tables. Certain embodiments of the present invention can detect mismatches in payloads through the protocol and help in diagnostic issues regarding squelching and provisioning of cross-connections. Some embodiments of the present invention have the flexibility to transmit protocol messages over the overhead SONET bytes or the DCC channels. Certain embodiments of the present invention use only 32 bits to communicate a squelch entry data to the neighboring node. Some embodiments of the present invention can transport information unrelated to squelching over a BLSR ring. Certain embodiments of the present invention use scalable and expandable protocol to cope with various BLSR rates for both STS and VT level squelching. For example, the BLSR rates may be those of OC-48, OC-192 and OC-768 Various additional objects, features and advantages of the present invention can be more fully appreciated with reference to the detailed description and accompanying drawings that follow. | 20040322 | 20080408 | 20051020 | 63403.0 | 0 | RIYAMI, ABDULLAH A | AUTOMATIC UPDATE OF SQUELCH TABLES FOR OPTICAL NETWORK APPLICATIONS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,806,586 | ACCEPTED | In-color fiber optic cable identification method | Herein described is a method and system for identifying buffer tubes in a cable by including at least one colored filling material within a transparent or translucent buffer tube. | 1. A cable, comprising at least one colored filling material disposed within a transparent or translucent buffer tube. 2. A cable, comprising a plurality of buffer tubes, wherein each buffer tube of said plurality contains a colored filling material. 3. The cable of claim 2, wherein the colored filling material within the buffer tubes of said plurality is color-coded. 4. The cable of claim 2, wherein the buffer tubes of said plurality are transparent or translucent. 5. The cable of claim 4, further comprising color-coded fibers. 6. The cable of claim 3, wherein the buffer tubes of said plurality are color-coded. 7. The cable of claim 6, further comprising: non-color-coded filling material; and transparent or translucent buffer tubes; wherein said non-color-coded filling material is disposed within said color-coded buffer tubes, and said color-coded filling material is disposed within said transparent or translucent buffer tubes. 8. The cable of claim 7, wherein said cable complies with EIA/TIA-598. 9. The cable of claim 8, further comprising up to 288 optical fibers, wherein each optical fiber is individually identifiable. 10. A cable, comprising: a plurality of transparent or translucent buffer tubes; a plurality of color-coded optical fibers within each buffer tube of said plurality; and color-coded filling material disposed within each buffer tube of said plurality; wherein each buffer tube contains a different color of filling material. 11. A system for identifying buffer tubes, comprising: a plurality of buffer tubes; and color-coded filling material; wherein said color-coded filling material is disposed within each buffer tube of said plurality. 12. The system of claim 11, wherein the buffer tubes of said plurality are transparent or translucent. 13. The system of claim 12, further comprising at least one ring, band marking, stripe or identification thread/tape for at least one transparent or translucent buffer tube of said plurality. 14. The system of claim 11, further comprising a plurality of color-coded buffer tubes. 15. The system of claim 11, further comprising a combination of color-coded buffer tubes and transparent or translucent buffer tubes. 16. The system of claim 15, further comprising: non-color-coded filling material; wherein said color-coded filling material is disposed within said transparent or translucent buffer tubes, and said non-color-coded filling material is disposed within said color-coded buffer tubes. 17. A system for identifying optical fibers, comprising: a plurality of transparent or translucent buffer tubes; color-coded optical fibers; and color-coded filling material disposed within at least one of said buffer tubes. 18. The system of claim 17, further comprising a plurality of color-coded buffer tubes; and non-color-coded filling material disposed within said color-coded buffer tubes. 19. A method for constructing a fiber optic cable, comprising: mixing a colorant into a filler material; and injecting said filler material into a buffer tube. 20. The method of claim 19, further comprising: extruding a buffer tube around at least one optical fiber. 21. A method for identifying or managing optical fibers in a cable, comprising: color-coding optical fibers; color-coding filling material; and including said filling material in at least one transparent or translucent buffer tubes. 22. The method of claim 21, further comprising color-coding buffer tubes. 23. A cable, comprising: a plurality of transparent or translucent buffer tubes; and means for identifying any one buffer tube of said plurality. 24. The cable of claim 23, wherein said means for identifying comprises color-coded buffer tube filler material disposed within at least two of said buffer tubes. 25. The cable of claim 24, wherein said means for identifying further comprises color-coded buffer tubes. 26. The cable of claim 24, wherein said means for identifying further comprises at least one ring or band marking around at least one of said buffer tubes. 27. A cable, comprising: a plurality of buffer tubes; optical fibers disposed within said plurality of buffer tubes; and means for identifying optical fibers in a cable without coloring said at least one buffer tube. 28. The cable of claim 27, wherein said means for identifying comprises: color-coded fibers; and color-coded filler material. 29. The cable of claim 28, wherein said means for identifying further comprises transparent or translucent buffer tubes. 30. The cable of claim 29, wherein said means for identifying further comprises a ring or band marking around at least one of said transparent or translucent buffer tubes. | FIELD OF THE INVENTION This invention relates to a communications cable. Particularly, this invention relates to fiber optic cable. More particularly, this invention relates to a method for identifying optical fibers and buffer tubes in a cable. BACKGROUND Optical fiber cables have been a very popular medium for communications and data transmission due to their high speeds and suitability over long distances. The transmission medium of optical fiber cables consist of thin optical fibers protected from external forces and elements by precisely designed and manufactured cable structures. One common cable structure used is the loose-tube cable. The loose-tube cable contains one or more buffer tubes arranged around a central strength member. The buffer tubes loosely encase one or more optical fibers, either in bundles or ribbons, thereby providing sufficient room for the fiber(s) to move within the buffer tube in response to applied stresses. The space inside the buffer tubes between the fibers and the buffer tube is filled with a waterblocking filling material to protect the fibers from water penetration. The buffer tubes can then be wrapped with binders, tapes, or yarns to provide additional strength and protection. Finally, the cable assembly is encased within a cable jacket to provide mechanical strength and protection from the environment. The loose-tube cable design permits easy drop-off of groups of fibers at intermediate points without interfering with other buffer tubes being routed to other locations. Since not all fibers, or groups of fibers, will always be routed to the same location or terminal application, it is necessary to be able to identify and distinguish among the various groups of fibers and among individual fibers. Because of the vast quantity of optical fibers that may be contained in an optical fiber cable, a color coding scheme is most commonly used to identify the buffer tubes and the individual optical fibers therein. This color-coding scheme generally consists of color-coding the buffer tubes and individual fibers. Usually the color-coding complies with EIA/TIA-598 color specifications. Traditionally, individually colored buffer tubes are produced by adding and mixing a colorant in an extruder or other high pressure mixing device prior to extrusion of each individual tube. Coloring buffer tubes requires mixing the buffer tube material with a color concentrate, or colorant, in an extruder or other high temperature and high pressure mixing device prior to extrusion each time a different tube color is desired. This results in substantial delays and down times just to change the tube color. Tube colorants can also be quite expensive. These colorants typically contain a pigment, dye or other coloring concentrate carried in a base resin. The buffer tube material and the base resin for the color concentrate should be the same type of material because of material incompatibility. Since the buffer tube material generally comprises polybutylene terephthalate (PBT), polyester elastomer, nylon, fluoropolymer, acetal resin or polycarbonate, the colorants that can be used become quite expensive. Finally, color-coding buffer tubes is not suitable for cables having a high number of buffer tubes. The buffer tubes of cables having more than twelve buffer tubes are marked by the placement of rings, bands, stripes or identification threads/tapes around or in the buffer tubes. These cables are expensive to produce, and require cutting away substantial portions of the outer jacket to locate any such marking. SUMMARY This specification describes a method and system for identifying buffer tubes in a cable by including at least one colored filling material within a transparent or translucent buffer tube. BRIEF DESCRIPTION OF THE DRAWINGS The products and processes described herein will be understood in light of the drawings, wherein: FIG. 1 illustrates a perspective side view of a buffer tube in an embodiment of the invention; and FIGS. 2-5 illustrate perspective side views of a group of buffer tubes in various embodiments of the invention. FIGS. 1-5 illustrate specific aspects of the products and processes described in the present specification and constitute a part of the specification. Together with the following description, the Figures demonstrate and explain the principles of the products and processes of the present invention. DETAILED DESCRIPTION The following description includes specific details in order to provide a thorough understanding of the novel cable and buffer tube and fiber identification and management system. The skilled artisan will understand, however, that the products and methods described below can be practiced without employing these specific details. Indeed, they can be modified and can be used in conjunction with products and techniques known to those of skill in the art. For example, this specification describes the novel cable and identification system with respect to loose-tube cables. The principles taught herein, however, may be applied to other types of cables, such as optical fiber ribbon cables, or any cable or device employing a filling material. It should be understood that the term “different color,” as used in the present specification and appended claims, refers to a color or shade of a color that is visually distinguishable from another color or shade of a color, unless otherwise noted. The term “same color” refers to colors or shades of a color that are visually indistinguishable, unless otherwise noted. This specification describes a fiber optic cable and a method of manufacture that makes use of a colored filling material injected into a translucent or transparent fiber buffer tube or tubes. This allows for the identification of fiber optic buffer tubes and management of the individual fibers without coloring the buffer tube itself. This fiber optic cable is created by mixing a colorant into the filling material just prior to its injection into the buffer tube. The process eliminates the need for tube coloring and allows the use of less expensive and more manufacturing-friendly color concentrates that are mixed into the filling material itself, not the buffer tube material. The colored filling material can be visible through the translucent or transparent fiber buffer tube material, thus allowing identification and classification of the various buffer tubes within the cable. In loose-tube cables the individual fibers are typically grouped into groups of six or twelve fibers, and each group is placed inside a buffer tube, separate from fibers in other buffer tubes. The filling material contained within a buffer tube serves a variety of functions. For example, the filling material inhibits water migration into the tube, and protects the fiber(s) within the tube from water absorption. The filling material that may be used includes any filling material known to those skilled in the art, such as gels, greases, petroleum jelly compounds, oils, and the like. As shown in FIG. 1, the novel optical fiber cable generally includes a colored filling material (15) disposed within at least one buffer tube (10). A buffer tube (10) may contain one or more optical fibers (11), each of which may be a different color from the other fibers (11) within the same buffer tube (10). FIG. 2 depicts multiple buffer tubes (10) of a single cable that are identified and distinguished by the color of the filling material (15) within each buffer tube (10). The filling material (15) provides a means for identifying and distinguishing the buffer tube (10) in which the filling material (15) is disposed from other buffer tubes within the same cable. This is done by color-coding the filling material (15) within the buffer tubes (10) of a cable. In an exemplary embodiment, filling material (12) may be blue, filling material (13) may be orange, and filling material (14) may be green. In an embodiment, the color-coding scheme complies with EIA/TIA-598 color specifications, which are incorporated herein by reference. According to these specifications, the filling material used within buffer tubes may be one of twelve colors: blue, orange, green, brown, slate, white, red, black, yellow, purple, rose, or aqua. The fibers within these buffer tubes may also be color-coded, typically according to EIA/TIA-598 specifications. Thus, a cable may contain up to twelve buffer tubes, each containing filling material of a different color. In another embodiment, each tube contains up to twelve differently colored individual fibers. Other color-coding schemes besides EIA/TIA-598 may also be followed, according to the desired application or other applicable rules and standards. Generally, though, no two buffer tubes of the same color will contain filling material of the same color. While most cables typically contain six or twelve optical fibers in each buffer tube, the cable described herein also contemplates buffer tubes having more or fewer fibers in each buffer tube. The filling material is colored by adding and mixing a colorant, such as a dye or pigment, into the filling material prior to its injection into a buffer tube. This process provides significant savings in money and processing time. The colorants for filling material are cheaper and easier to use because they do not require an expensive base resin, unlike the colorants used in prior art buffer tube materials. Suitable dyes that may be used include, but are not limited to, azo dyes, diazodyes, pyrazolones, quinolones, quinophthalones, anthraquinones and nigrosines. Useful pigments include any substance that imparts a desired color to the filling material. Suitable pigments include, but are not limited to, organic pigments such as benzimidazolones (yellow, red, orange), phthalocyanimes (blue, green), quinacsidones (violet, red, orange), dioxanes (violet), isoindolinones (yellow, red, orange), disazos (yellow, red), pyrazalones (orange, red), diarylides (yellow, orange), dianisidines (orange); inorganic pigments such as titanium dioxide (white), lead chromates (yellow, orange), iron oxides (brown, red, maroon, yellow, black), chromium oxide (green), cadmium sulfoselenides (maroon, red, orange), lithopone (white), ultramarine blue (aluminosilicate complex with sulfur), nickel titanate (yellow), cobalt aluminate (blue), zinc chromate (yellow), lead molybdate (orange), cadmium sulfide (orange); lake pigments; pearlescent colorants; and daylight fluorescent colorants. Using color-coded fibers and color-coded filling material thus provides a two-level buffer tube and fiber identification and management system for optical fiber cables. The buffer tubes in such a two-level fiber identification and management system may consist of any one color. In an embodiment, as shown in FIG. 2, the buffer tubes (10) are transparent or translucent. Such buffer tubes (10) are identified and distinguished by the color of the filling material (15) within each buffer tube (10), rather than by the color of the buffer tube (10) itself. Suitable buffer tube materials that may be used include, but are not limited to, polyethylene, polypropylene, polybutylene terephthalate (PBT), polyamide, polyester elastomer, nylon, fluoropolymer, acetal resin, polycarbonate, a layered combination, and the like. Transparent or translucent buffer tubes provide significant advantages and benefits to colored buffer tubes. They significantly decrease costs of making the buffer tubes, and since they are not colored they eliminate the need for expensive colorants having a base resin made from the buffer tube material. Also, producing transparent or translucent buffer tubes requires the use of only one buffer tube material, thereby eliminating the step of changing and mixing the colorant. This substantially decreases the processing time and associated costs. The buffer tubes may also be color-coded, and need not be transparent or translucent, as shown in FIG. 3. An optical fiber cable containing color-coded buffer tubes (30) in conjunction with color-coded filling material (35) and color-coded optical fibers (32) provides a three-level system for identifying and managing the optical fibers (32) within a cable. Such a system has several advantages. First, it permits construction of a cable with a very high number of fibers (32) while allowing identification of any individual fiber (32) within the cable. Second, buffer tubes (30) are identified by the color of the buffer tube (30) and filling material (35), rather than by rings, bands, stripes or identification threads/tapes as used in prior art cables. According to an embodiment of the identification method described herein, access to the cable may be sped up due to the ability to identify tubes and/or fibers more quickly. To provide additional methods and systems of identifying and managing optical fibers in a cable, different combinations of color-coded buffer tubes and color-coded filling material may be used. FIG. 4 shows an embodiment in which the novel fiber optic cable comprises both transparent or translucent buffer tubes (40) having color-coded filler material (45) and color-coded buffer tubes (41) having non-color-coded filler material (46). According to this embodiment, a cable following the EIA/TIA-598 color specifications can have up to twelve color-coded buffer tubes (41), and up to twelve transparent or translucent buffer tubes (40) identified by the color of the filling material (45), for a total of twenty-four visually distinguishable and identifiable buffer tubes. Each buffer tube (40, 41) may have up to twelve color-coded fibers (42), thereby allowing the cable to have up to 288 individually identifiable fibers. Furthermore, other techniques known to those in the art may be used in combination with the principles described herein. For example, a third-level of identification of buffer tubes can be achieved by using ring or band markings around one or more buffer tubes at various or regular intervals, in addition to using color-coded filling material and color-coded fibers. This can be suitable for cables having high numbers of buffer tubes. FIG. 5 depicts an embodiment in which the cable has only transparent or translucent buffer tubes (50), and contains color-coded filling material (55) and color-coded optical fibers (52). At least one of the buffer tubes (50) has rings (53) to distinguish the buffer tube from other buffer tubes in the same cable. Thus, a cable complying with EIA/TIA-598 may contain more than twelve individually identifiable buffer tubes. In another embodiment, such a system may also include color-coded buffer tubes in addition to transparent or translucent buffer tubes. The cable of the present invention is made in a manner that substantially decreases the time and costs associated with processing buffer tubes and fiber optic cables. Generally, the filler material colorant is mixed into the filler material prior to injection of the filler material into the buffer tubes to create a colored filler material. The buffer tubes can then be extruded around the optical fibers. In an embodiment, the buffer tube material contains no added colorants, thereby creating a transparent or translucent buffer tube when extruded. The steps of adding and mixing colorant into the buffer tube material, and then changing the buffer tube material for a subsequent tube extrusion, can be eliminated, increasing the processing time. In another embodiment, the buffer tube material is also colored by adding and mixing a tube colorant to the buffer tube material prior to extrusion. The buffer tube is extruded around the fibers while the colored filler material is injected into the buffer tubes. Those skilled in the art will recognize that methods other than those described above, but known to those of skill in the art, may also be employed to make transparent or translucent, or colored buffer tubes. The novel cable can also include other components to provide additional strength, protection, durability, and other desirable properties. For example, the cable may include yarns, tapes, binders, armors, shields, flooding material, strength members, jackets and other cable components known to those of skill in the art. The preceding description has been presented only to illustrate and describe exemplary embodiments of the novel cable and buffer tube and fiber identification and management system. It is not intended to be exhaustive or to limit the products and processes to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the products and processes be defined by the following claims. | <SOH> BACKGROUND <EOH>Optical fiber cables have been a very popular medium for communications and data transmission due to their high speeds and suitability over long distances. The transmission medium of optical fiber cables consist of thin optical fibers protected from external forces and elements by precisely designed and manufactured cable structures. One common cable structure used is the loose-tube cable. The loose-tube cable contains one or more buffer tubes arranged around a central strength member. The buffer tubes loosely encase one or more optical fibers, either in bundles or ribbons, thereby providing sufficient room for the fiber(s) to move within the buffer tube in response to applied stresses. The space inside the buffer tubes between the fibers and the buffer tube is filled with a waterblocking filling material to protect the fibers from water penetration. The buffer tubes can then be wrapped with binders, tapes, or yarns to provide additional strength and protection. Finally, the cable assembly is encased within a cable jacket to provide mechanical strength and protection from the environment. The loose-tube cable design permits easy drop-off of groups of fibers at intermediate points without interfering with other buffer tubes being routed to other locations. Since not all fibers, or groups of fibers, will always be routed to the same location or terminal application, it is necessary to be able to identify and distinguish among the various groups of fibers and among individual fibers. Because of the vast quantity of optical fibers that may be contained in an optical fiber cable, a color coding scheme is most commonly used to identify the buffer tubes and the individual optical fibers therein. This color-coding scheme generally consists of color-coding the buffer tubes and individual fibers. Usually the color-coding complies with EIA/TIA-598 color specifications. Traditionally, individually colored buffer tubes are produced by adding and mixing a colorant in an extruder or other high pressure mixing device prior to extrusion of each individual tube. Coloring buffer tubes requires mixing the buffer tube material with a color concentrate, or colorant, in an extruder or other high temperature and high pressure mixing device prior to extrusion each time a different tube color is desired. This results in substantial delays and down times just to change the tube color. Tube colorants can also be quite expensive. These colorants typically contain a pigment, dye or other coloring concentrate carried in a base resin. The buffer tube material and the base resin for the color concentrate should be the same type of material because of material incompatibility. Since the buffer tube material generally comprises polybutylene terephthalate (PBT), polyester elastomer, nylon, fluoropolymer, acetal resin or polycarbonate, the colorants that can be used become quite expensive. Finally, color-coding buffer tubes is not suitable for cables having a high number of buffer tubes. The buffer tubes of cables having more than twelve buffer tubes are marked by the placement of rings, bands, stripes or identification threads/tapes around or in the buffer tubes. These cables are expensive to produce, and require cutting away substantial portions of the outer jacket to locate any such marking. | <SOH> SUMMARY <EOH>This specification describes a method and system for identifying buffer tubes in a cable by including at least one colored filling material within a transparent or translucent buffer tube. | 20040323 | 20070911 | 20050929 | 66801.0 | 0 | BLEVINS, JERRY M | IN-COLOR FIBER OPTIC CABLE IDENTIFICATION METHOD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,806,624 | ACCEPTED | LEAKAGE CURRENT REDUCTION METHOD | The method for powering down a circuit for a data retention mode includes: changing a supply voltage node from an active power voltage level to an inactive power level; coupling a source of a P channel device to the supply voltage node; providing a retaining power supply voltage level to a back gate of the P channel device; changing a drain voltage of the P channel device to a reference voltage level, wherein the reference voltage level is different from the retaining power supply voltage level; and changing a gate voltage of the P channel device to the reference voltage level. | 1. A method for powering down a circuit for a data retention mode comprising: changing a supply voltage node from an active power voltage level to an inactive power level; coupling a source of a P channel device to the supply voltage node; providing a retaining power supply voltage level to a back gate of the P channel device; changing a drain voltage of the P channel device to a reference voltage level, wherein the reference voltage level is different from the retaining power supply voltage level; and changing a gate voltage of the P channel device to the reference voltage level. 2. The method of claim 1 wherein the reference voltage level is less than the retaining power supply voltage level. 3. The method of claim 1 wherein the reference voltage level is less than half the retaining power supply voltage level. 4. The method of claim 1 wherein the P channel device is in a wordline circuit. 5. The method of claim 1 further comprising: coupling a second P channel device in series with the first P channel device; coupling a first N channel device in series with the second P channel device; and coupling a second N channel device in series with the first N channel device. 6. The method of claim 5 further comprising: providing the retaining power supply voltage level to a source of the second N channel device; changing a drain of the N channel device to the reference voltage level; and changing a gate voltage of the N channel device to the reference voltage level. 7. The method of claim 1 wherein the retaining power supply voltage level is the same as the active power voltage level. 8. The method of claim 1 wherein the active power voltage level is 1.3V, the inactive power level is 0V, the reference voltage level is 0.6V, the retaining power supply voltage level is 1.3V. | FIELD OF THE INVENTION The present invention relates to electronic circuitry and, in particular, to a leakage current reduction method. BACKGROUND OF THE INVENTION In a prior approach for powering down a circuit system, when the system goes into sleep/data retention mode, the main power supply VDD goes from 1.3V (in active mode) to near 0V, a retaining power supply VRET remains unchanged at, for example, 1.3V, a retain signal RET goes from 0V to VRET (1.3V) level, and some internal nodes of the system are raised to a reference voltage VBB level (for example 0.6V). For circuits whose data needs to be retained when the system goes into sleep/data retention mode, the typical way of turning off the P Channel (PCH) device is shown below: Vdrain=VBB (0V-->0.6V, for example) Vgate=RET (0-->1.3V, for example) Vsource=VDD (1.3V-->0V, for example) Vbulk=VRET (1.3V, for example) This is demonstrated in the wordline circuit shown in FIG. 1. This circuit has a P channel device 20 as a header. The circuit also includes P channel device 22, N channel device 24, and N channel device 26. When this circuit goes into sleep/data retention mode, source voltage Vsource goes from the active level power supply level VDD (for example 1.3V) to 0V; the drain voltage Vdrain goes to the reference voltage VBB (for example 0.6V); the gate voltage Vgate goes to the retain signal RET, which goes from 0V to retaining power supply VRET (1.3V, for example); and the back gate Vbulk goes to the retaining power supply VRET. The problem with this prior art solution is that large voltage differences between the gate (1.3V) and the source (0V)/drain (0.6V) exist which results in large gate tunneling leakage, which dominates the P channel device leakage at room temperature since the sub-threshold leakage is suppressed by the deep back-gate bias. This leads to high standby power consumption. SUMMARY OF THE INVENTION A method for powering down a circuit for a data retention mode includes: changing a supply voltage node from an active power voltage level to an inactive power level; coupling a source of a P channel device to the supply voltage node; providing a retaining power supply voltage level to a back gate of the P channel device; changing a drain voltage of the P channel device to a reference voltage level, wherein the reference voltage level is different from the retaining power supply voltage level; and changing a gate voltage of the P channel device to the reference voltage level. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: The DRAWING is a diagram of a wordline circuit with a P channel device as header. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The preferred embodiment solution to this problem is to raise the gate of the P channel device 20 to reference voltage VBB (0.6V, for example), instead of retain signal RET (1.3V, for example) when the system goes into sleep/data retention mode, as shown below: Vdrain=VBB (0V-->0.6V) Vgate=VBB (0-->0.6V) Vsource=VDD (1.3V-->0V) Vbulk=VRET (1.3V) Since the voltage differences between the gate (0.6V) and the source (0V)/drain (0.6V) are greatly reduced, the gate tunneling leakage and standby power consumption are also greatly reduced. In fact, the leakage from the reference voltage node VBB does not contribute to any power consumption, since it is provided by the leakage from other parts of the system such as retention SRAM arrays. A similar method can be applied to turn off the N channel device if e.g. the source is raised from 0V to 1.3V (retaining voltage), drain is raised from 0V to 0.6V (reference voltage VBB), and bulk remains at 0V when the system goes into sleep/data retention mode. In such a case, the gate can be raised to reference voltage VBB instead of kept at 0V. One advantage of the preferred embodiment circuit is that it saves large gate leakage that helps meet leakage budget requirements when the circuit is in power down mode. Another advantage is that the leakage from the reference voltage source VBB does not contribute to any power consumption, since it is provided by the leakage from other parts of the system such as retention SRAM arrays. While this invention has been described with reference to an illustrative embodiment, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiment, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments. | <SOH> BACKGROUND OF THE INVENTION <EOH>In a prior approach for powering down a circuit system, when the system goes into sleep/data retention mode, the main power supply VDD goes from 1.3V (in active mode) to near 0V, a retaining power supply VRET remains unchanged at, for example, 1.3V, a retain signal RET goes from 0V to VRET (1.3V) level, and some internal nodes of the system are raised to a reference voltage VBB level (for example 0.6V). For circuits whose data needs to be retained when the system goes into sleep/data retention mode, the typical way of turning off the P Channel (PCH) device is shown below: Vdrain=VBB (0V-->0.6V, for example) Vgate=RET (0-->1.3V, for example) Vsource=VDD (1.3V-->0V, for example) Vbulk=VRET (1.3V, for example) This is demonstrated in the wordline circuit shown in FIG. 1 . This circuit has a P channel device 20 as a header. The circuit also includes P channel device 22 , N channel device 24 , and N channel device 26 . When this circuit goes into sleep/data retention mode, source voltage Vsource goes from the active level power supply level VDD (for example 1.3V) to 0V; the drain voltage Vdrain goes to the reference voltage VBB (for example 0.6V); the gate voltage Vgate goes to the retain signal RET, which goes from 0V to retaining power supply VRET (1.3V, for example); and the back gate Vbulk goes to the retaining power supply VRET. The problem with this prior art solution is that large voltage differences between the gate (1.3V) and the source (0V)/drain (0.6V) exist which results in large gate tunneling leakage, which dominates the P channel device leakage at room temperature since the sub-threshold leakage is suppressed by the deep back-gate bias. This leads to high standby power consumption. | <SOH> SUMMARY OF THE INVENTION <EOH>A method for powering down a circuit for a data retention mode includes: changing a supply voltage node from an active power voltage level to an inactive power level; coupling a source of a P channel device to the supply voltage node; providing a retaining power supply voltage level to a back gate of the P channel device; changing a drain voltage of the P channel device to a reference voltage level, wherein the reference voltage level is different from the retaining power supply voltage level; and changing a gate voltage of the P channel device to the reference voltage level. | 20040323 | 20051018 | 20050929 | 99256.0 | 0 | TRAN, ANH Q | LEAKAGE CURRENT REDUCTION METHOD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,806,696 | ACCEPTED | Wrench | A socket for easily connecting and disconnecting a standard camlock fitting, such as those used in flanges on marine vessels, includes four drive lugs, or tangs, for mating with recesses on the camlock. The socket is adapted for connection to a standard ratchet wrench for providing torque to tighten or loosen the camlocks. | 1. A socket for use with a ratchet wrench comprising: a socket body having a hollowed-out portion for receiving therein and surrounding the threaded cam bolt head of a standard camlock on a camlock coupling; a ratchet drive fitting for receiving the engagement head of a standard ratchet wrench and for driving said socket with said standard ratchet wrench; and a plurality of tangs for engaging with cam turning slots of said standard camlock. 2. The socket of claim 1 further including: A shoulder on said socket body for engaging with and depressing a ratchet lock pawl on said camlock. 3. The socket of claim 1 wherein said plurality of tangs is four. 4. The socket of claim 2 wherein said plurality of tangs is four. | BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is related to tools for connecting and disconnecting flanges such as those used at a refinery or on a barge. 2. Description of Related Art U.S. Pat. No. 6,101,904 discloses an improved flange removal tool for facilitating the installation and removal of pipe flanges from a receiving pipe fitting. The flange tool includes a body portion with an upper surface which includes a central opening for receiving an engagement head of a socket wrench. A continuous frame is attached to the body portion by spaced arms such that the continuous frame is suspended in spaced relation from the lower surface of the body portion by a distance which is greater than the thickness of a pipe flange to be rotated. The pipe flange is positioned between the body portion and the frame so that upon rotation of the flange tool, facilitated by engagement of a socket wrench with the central opening, side walls of the spaced arms contact the edges of the pipe flange to urge rotation thereof and threading onto its receiving pipe fitting. U.S. Pat. No. 5,839,331 discloses a flange tightening tool for use in securing a flange to a pipe. The tool has a base plate, a tightening hexagonal shoulder, two attachment openings, two quick release disconnect mechanisms and a rotating handle perpendicular to the tightening base plate. The hexagonal shoulder enables the tool to be used with a companion lightweight wrench. The tool can also be used with an open end wrench or an adjustable wrench. A rotatable handle is attached to the hexagonal shoulder such that said handle is perpendicular to the face of a flange that is to be tightened and can be used to hold the tool against the flange. When the quick release disconnect mechanisms are depressed about the pivot pin the quick release disconnect mechanism detracts from the mounting members releasing the mounting member separating the base plate and the flange. The tool prevents over tightening since the flange cannot be tightened past the point where the pipe contacts the base plate. An adapter plate enables the tool to be used with an additional size of flange. In U.S. Pat. No. 4,237,755 the pipe flange tool for tightening or removing threaded pipe flanges includes a base having at least three engaging pins laterally extending from one side of the base and means for rotationally engaging the base. The engaging pins are positioned on the base such that at least two of the pins cooperate to tighten or remove various threaded pipe flanges as are commonly used for forming circulating pumps to pipes. The tool base may be provided with a bore in the base itself or it may have a laterally extending hub having a bore sized to receive a conventional socket wrench. The base may also be provided with pins having various configurations including cylindrical or frusto-conical. U.S. Pat. No. 4,181,048 discloses a flange turning tool adapted for use with flanged pipe couplings, wherein the wrench comprises a head member having a reduced, extending, jaw member which is provided with a cylindrical key pin that extends laterally and outwardly therefrom. The key pin is arranged to be received in any one of a plurality of openings located about the flange member of the pipe coupling. The annular periphery of a thrust flange will engage the shoulder defined by the rear enlarged portion of the head member. The head member has a threaded bore to receive a conventional bar or extension handle. When force is applied to the bar, the flange is locked between the key pin and shoulder and is then either tightened or untightened, depending on the direction of force applied thereto. British Patent GB 2,318,315 relates to a device for securing a threaded flange to the threaded end portion of a pipe. SUMMARY OF THE INVENTION A socket for easily connecting and disconnecting a standard camlock fitting, such as those used in flanges on marine vessels, includes four drive lugs, or tangs, for mating with recesses on the camlock. The socket is adapted for connection to a standard ratchet wrench for providing torque to tighten or loosen the camlocks. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a side elevation view of a standard camlock flange coupling in initial engagement with a mating flange with the camlocks fully open for receiving a mating flange. FIG. 1B is a front elevation view of the camlock flange coupling with the camlocks fully open. FIG. 1C is a depiction of the flange with camlocks in their engaged (tightened) position. FIG. 2A is a plan view of a prior art wrench used for tightening the camlocks. FIG. 2B is a side view of the wrench of FIG. 2A. FIG. 2C is a side view of a camlock in alignment with the wrench of FIGS. 2A and 2B. FIG. 3 is a perspective view of another prior art wrench. FIG. 4 is a perspective view of a camlock beginning engagement with a mating flange. FIG. 5 is a perspective view of a socket according to the present invention. FIG. 6A is a plan view of the socket of FIG. 5. FIG. 6B is a side view of the socket of FIG. 6A. FIG. 7 is a perspective view of the socket of FIG. 5 beginning engagement with a camlock. FIG. 8 is a close-up view of the engagement mechanism of the socket of FIG. 5 with the camlock. DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, a standard camlock flange coupling 10, well known to those skilled in the art is shown. The coupling 10 may be affixed to a pipe manifold side or to the end of a connection hose. For ease of illustration, flange coupling 10 is shown as being fixedly attached, such as by welding 12, to coupling pipe 10a. Couplings 10 are also available in studded and slip-on types. Coupling 10 also comprises a plurality of camlocks 13 also well known by those skilled in the art. Each camlock 13 comprises a plurality of turning slots 13a (shown more clearly in FIG. 1B and in FIG. 4) and a ratchet lock pawl 13b and are threaded onto cam bolt pins 13c. It will be appreciated that ratchet pawl 13b is shown in its locked position and includes an inclined face 13b1 to facilitate an unlocking movement when engaged by a wrench. The coupling 10 also includes an o-ring 14 for sealing the mating flange surfaces. When it is desired to attach a pipe 11 having a flange 11a to the coupling 10, the camlocks 13 are positioned in their fully open position as shown in FIG. 1B. When the surface of flange 11a comes into close proximity with the face of coupling pipe 10a, such as at 10b, the camlocks 13 may be tightened by hand onto their threaded bolt pin 13c (by depressing pawl 13b) and, after hand tightening, are subsequently tightened by a wrench such as wrench 20 shown in FIG. 2. As the wrench is applied over the bolt head, the spring-loaded pawl 13b will be pushed back to a non-ratchet position when the wrench tang 21 engages one of the turning slots 13a. The camlock 13 is locked by rotation in the clockwise direction. When the wrench 20 is removed, the pawl 13b will automatically engage a ratchet wheel fixed to the stationary cam bolt thereby locking the cam in place. FIG. 2 shows a wrench 20 which is well known to those skilled in the art. The wrench 20 includes a tang 21 for mating with the tang turning slot 13a for further tightening. It will be noticed that the wrench 20 includes only one such tang 21 thereby limiting the possible mating positions with the turning slot 13a. The pawl 13b, grease fittings 13d and cam bolt pins 13e are well known in the art. Referring now to FIG. 3, another prior art wrench is shown having turning tangs (or lugs) 30a and 30b. This wrench provides a more positive turning action but is still limited by the mating positions available. FIG. 4 shows a camlock 13 partially tightened onto a mating pipe flange 11a. Note that, since no wrench is attached over the camlock 13, the ratchet pawl 13b is fully extended, thereby locking the cam 13 in place. Referring now to FIG. 5 a socket 50 according to the present invention includes a plurality of lugs or turning tangs 50a-50d evenly spaced around the periphery of the socket 50 and includes the usual ratchet drive fitting 50e. A ratchet wrench 52 is shown engaged with the socket 50 in the usual manner with the engagement head 52a of ratchet wrench 52 protruding into the ratchet drive fitting 50e of socket 50. Refer now to FIGS. 6A and 6B which show plan and side views, respectively, of the socket 50 having an overall depth 50h. As the shoulder 50f of socket 50 engages the ramp 13b1 of pawl 13b, the pawl is pushed outwardly, as shown by the arrows in FIG. 2C, thereby allowing the cam 13 to be turned, i.e., tightened or loosened. The dimension 50g and inner diameter of shoulder 50f are selected such that when the socket 50 is fully seated over a camlock 13, the ratchet lock pawl 13b will be completely depressed into camlock 13 by the shoulder 50f of socket 50 thereby disengaging the ratchet wheel of the stationary cam bolt and allowing rotation of the cam 13. FIG. 7 is a perspective view of a socket 50 in accordance with the invention shown in FIGS. 5 and 6, partially seated on a camlock 13. A ratchet wrench 52 is shown in place for tightening of the camlock 13. It will be appreciated that, since pawl 13b is not fully depressed by shoulder 50f of socket 50, the cam 13 is not free to turn. FIG. 8 shows a close-up view of a lug or tang 52a-d in mating engagement in a cam turning slot 13a. In this position, the pawl 13b is completely pushed outwardly by the shoulder 50f, therefore the cam 13 is free to turn. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The invention is related to tools for connecting and disconnecting flanges such as those used at a refinery or on a barge. 2. Description of Related Art U.S. Pat. No. 6,101,904 discloses an improved flange removal tool for facilitating the installation and removal of pipe flanges from a receiving pipe fitting. The flange tool includes a body portion with an upper surface which includes a central opening for receiving an engagement head of a socket wrench. A continuous frame is attached to the body portion by spaced arms such that the continuous frame is suspended in spaced relation from the lower surface of the body portion by a distance which is greater than the thickness of a pipe flange to be rotated. The pipe flange is positioned between the body portion and the frame so that upon rotation of the flange tool, facilitated by engagement of a socket wrench with the central opening, side walls of the spaced arms contact the edges of the pipe flange to urge rotation thereof and threading onto its receiving pipe fitting. U.S. Pat. No. 5,839,331 discloses a flange tightening tool for use in securing a flange to a pipe. The tool has a base plate, a tightening hexagonal shoulder, two attachment openings, two quick release disconnect mechanisms and a rotating handle perpendicular to the tightening base plate. The hexagonal shoulder enables the tool to be used with a companion lightweight wrench. The tool can also be used with an open end wrench or an adjustable wrench. A rotatable handle is attached to the hexagonal shoulder such that said handle is perpendicular to the face of a flange that is to be tightened and can be used to hold the tool against the flange. When the quick release disconnect mechanisms are depressed about the pivot pin the quick release disconnect mechanism detracts from the mounting members releasing the mounting member separating the base plate and the flange. The tool prevents over tightening since the flange cannot be tightened past the point where the pipe contacts the base plate. An adapter plate enables the tool to be used with an additional size of flange. In U.S. Pat. No. 4,237,755 the pipe flange tool for tightening or removing threaded pipe flanges includes a base having at least three engaging pins laterally extending from one side of the base and means for rotationally engaging the base. The engaging pins are positioned on the base such that at least two of the pins cooperate to tighten or remove various threaded pipe flanges as are commonly used for forming circulating pumps to pipes. The tool base may be provided with a bore in the base itself or it may have a laterally extending hub having a bore sized to receive a conventional socket wrench. The base may also be provided with pins having various configurations including cylindrical or frusto-conical. U.S. Pat. No. 4,181,048 discloses a flange turning tool adapted for use with flanged pipe couplings, wherein the wrench comprises a head member having a reduced, extending, jaw member which is provided with a cylindrical key pin that extends laterally and outwardly therefrom. The key pin is arranged to be received in any one of a plurality of openings located about the flange member of the pipe coupling. The annular periphery of a thrust flange will engage the shoulder defined by the rear enlarged portion of the head member. The head member has a threaded bore to receive a conventional bar or extension handle. When force is applied to the bar, the flange is locked between the key pin and shoulder and is then either tightened or untightened, depending on the direction of force applied thereto. British Patent GB 2,318,315 relates to a device for securing a threaded flange to the threaded end portion of a pipe. | <SOH> SUMMARY OF THE INVENTION <EOH>A socket for easily connecting and disconnecting a standard camlock fitting, such as those used in flanges on marine vessels, includes four drive lugs, or tangs, for mating with recesses on the camlock. The socket is adapted for connection to a standard ratchet wrench for providing torque to tighten or loosen the camlocks. | 20040323 | 20060905 | 20050929 | 93508.0 | 0 | OJINI, EZIAMARA ANTHONY | WRENCH | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,016 | ACCEPTED | Vascular-access simulation system with ergonomic features | The illustrative embodiment is a simulation system for practicing vascular-access procedures without using human subjects. The simulator includes a data-processing system and a haptics interface device. The haptics device provides the physical interface at which a user interacts with various mechanisms that are intended to enable the user to simulate various aspects of a vascular-access procedure. The haptics device is designed so that its physical form and manner of use are not inconsistent with the experience of performing an actual vascular access procedure. | 1. An apparatus comprising: pseudo skin; a receiver, wherein said receiver receives an end effector; and a first device for performing a first skin-interaction technique, wherein said receiver and said first device are disposed beneath said pseudo skin. 2. The apparatus of claim 1 wherein an insertion region for said end effector is defined at a site at which said end effector is received by said receiver, and wherein said insertion region is proximal to a first region of said pseudo skin. 3. The apparatus of claim 2 wherein: said first skin-interaction technique comprises at least one of either palpation or occlusion; a second region of said pseudo skin is accessible to perform said first skin-interaction technique; and said first region of said pseudo skin is closer to a user than said second region of said pseudo skin when said user is using said apparatus. 4. The apparatus of claim 2 further comprising a second device for performing a second skin-interaction technique, wherein said second device is disposed beneath said pseudo skin. 5. The apparatus of claim 4 wherein: said second skin-interaction technique comprises skin stretching; a third region of said pseudo skin is accessible to perform said second skin-interaction technique; and said third region of said pseudo skin is closer to a user than said first region of said pseudo skin when said user is using said apparatus. 6. The apparatus of claim 1 further comprising a housing, wherein said housing has an anterior portion, a posterior portion, an upper surface and a lower surface wherein, in use: said anterior portion is proximal to a user; said posterior portion is distal to said user; said lower surface is proximal to a support surface on which said apparatus resides; and said upper surface is distal to said support surface. 7. The apparatus of claim 6 wherein said upper surface is no more than about 5 inches above said lower surface. 8. The apparatus of claim 6 wherein said housing comprises at least one opening proximal to said upper surface thereof to access said pseudo skin. 9. The apparatus of claim 6 wherein said housing comprises a handle proximal to said anterior portion by which a user grips said apparatus during use. 10. The apparatus of claim 6 wherein: an insertion region for said end effector is defined at a site at which said end effector is received by said receiver; said insertion region is proximal to a first region of said pseudo skin; and a first end of said receiver is relatively closer to said insertion region and a second end of said receiver is relatively further from said insertion region. 11. The apparatus of claim 10 wherein: said first skin-interaction technique comprises at least one of either palpation or occlusion; and said first end of said receiver is closer to said anterior portion of said housing than said first device. 12. The apparatus of claim 10 wherein: said first skin-interaction technique comprises at least one of either palpation or occlusion; and an upper-most surface of said first device extends a greater distance above said lower surface of said housing than said first end of said receiver. 13. The apparatus of claim 10 further comprising a second device for performing a second skin-interaction technique, wherein said second device is disposed beneath said pseudo skin. 14. The apparatus of claim 13 wherein: said first skin-interaction technique comprises one of either palpation or occlusion; and said second skin-interaction technique comprises skin-stretch. 15. The apparatus of claim 14 wherein at least some portion of said second device is closer to said anterior portion of said housing than said first device. 16. The apparatus of claim 14 wherein at least some portion of said second device is closer to said anterior portion of said housing than said first end of said receiver. 17. The apparatus of claim 14 wherein said first end of said receiver is closer to said anterior portion of said housing than said first device. 18. The apparatus of claim 14 wherein an upper-most surface of said first device extends a greater distance above said lower surface of said housing than said first end of said receiver. 19. The apparatus of claim 14 wherein an upper-most surface of said first device extends further above said lower surface of said housing than an upper-most surface of said second device. 20. The apparatus of claim 1 wherein at least a portion of said receiver is disposed beneath an upper-most surface of said first device. 21. The apparatus of claim 6 further comprising an electronics/communications interface, wherein: said electronics/communications interface receives signals from sensors that are associated with at least one of said first device or said receiver; and said electronics/communications interface is disposed beneath said pseudo skin. 22. The apparatus of claim 21 wherein said electronics/communications interface is closer to said posterior portion of said housing than said first device. 23. The apparatus of claim 21 wherein said electronics/communications interface is closer to said posterior portion of said housing than said receiver. 24. The apparatus of claim 21 wherein said electronics/communications interface comprises a printed circuit board, and further wherein a major surface of said printed circuit board is disposed orthogonal to an uppermost surface of said first device. 25. An apparatus comprising: a housing; an end effector, wherein said end effector is inserted into said housing during the performance of a simulated vascular-access procedure; and a plurality of mechanisms, wherein said plurality of mechanisms are contained completely within said housing, and wherein said plurality of mechanisms include: a first mechanism is for simulating a first skin-interaction technique; and a second mechanism for receiving said end effector. 26. The apparatus of claim 25 wherein: said housing has a longitudinal axis; a first end of said longitudinal axis defines an anterior portion of said housing; a second end of said longitudinal axis defines a posterior portion of said housing; and in use, said anterior portion is proximal to a user and said posterior portion is distal to said user. 27. The apparatus of claim 25 wherein said plurality of mechanisms are disposed beneath a pseudo skin. 28. The apparatus of claim 25 wherein said mechanisms includes a third mechanism for simulating a second skin-interaction technique, and wherein said end effector is at least one of either a needle or a catheter. 29. The apparatus of claim 28 wherein: said first skin-interaction technique is skin-stretch; said second skin-interaction technique is at least one of either palpation or occlusion; and at least a portion said first mechanism is disposed at a substantially different position along said longitudinal axis than said second mechanism and said third mechanism. 30. The apparatus of claim 28 wherein: said first skin-interaction technique is skin-stretch; said second skin-interaction technique is at least one of either palpation or occlusion; and said first mechanism is closer to said anterior portion of said housing than said second mechanism and said third mechanism. 31. The apparatus of claim 28 wherein: said first skin-interaction technique is skin-stretch; said second skin-interaction technique is at least one of either palpation or occlusion; and at least a portion said second mechanism is disposed at a substantially different position along said longitudinal axis than said first mechanism and said third mechanism. 32. The apparatus of claim 28 wherein: said first skin-interaction technique is skin-stretch; said second skin-interaction technique is at least one of either palpation or occlusion; and said third mechanism is closer to said posterior portion of said housing than said first mechanism and said second mechanism. 33. The apparatus of claim 31 wherein said portion of said second mechanism is flanked by said first mechanism and said third mechanism along said longitudinal axis. 34. The apparatus of claim 28 wherein: a user interacts with said first mechanism at a first site at an upper surface of said housing; said user interacts with said second mechanism at a second site at said upper surface of said housing; said user interacts with said third mechanism at a third site at said upper surface of said housing; and a position of each of said first site, second site, and third site along said longitudinal axis corresponds to said positions of said respective first mechanism, second mechanism, and third mechanism along said longitudinal axis. 35. An apparatus comprising: a pseudo skin; a plurality of mechanisms with which a user interacts for simulating a vascular-access procedure, wherein said plurality of mechanisms are disposed under said skin; and a housing, wherein said housing contains said plurality of mechanisms. 36. The apparatus of claim 35 wherein said housing is no more than about 5 inches in height. 37. The apparatus of claim 35 wherein said housing is no more than about 4 inches in height. 38. The apparatus of claim 35 wherein at least one of either a needle or catheter is disposed outside of said housing until inserted therein during a simulated vascular-access procedure. 39. The apparatus of claim 35 further comprising a data processing system, wherein said data processing system receives signals from sensors that are associated with said plurality of mechanisms. 40. The apparatus of claim 35 wherein said plurality of mechanisms comprise discrete devices, wherein a first of said devices is for enabling a user to perform a skin-stretch technique, a second of said devices is for receiving a needle or catheter or both, and a third of said devices is for enabling a user to perform at least one of either a palpation technique or an occlusion technique. | STATEMENT OF RELATED CASES This case is related to U.S. patent applications Ser. No. ______ (Atty. Dkt. No. 115-001), Ser. No. ______ (Atty. Dkt. No. 115-002), Ser. No. ______ (Atty. Dkt. No. 115-003), and Ser. No. ______ (Atty. Dkt. No. 115-005), all of which are incorporated by reference herein. FIELD OF THE INVENTION The present invention relates generally to systems that simulate medical procedures for the purposes of training or accreditation. More particularly, the present invention relates to a system, apparatus and subsystems for simulating vascular-access procedures. BACKGROUND OF THE INVENTION Medical practitioners, such as military medics, civilian emergency-medical personnel, nurses, and physicians, routinely perform vascular-access procedures (e.g., IV insertion, central venous-line placement, peripherally-inserted central catheter, etc). It is desirable for a practitioner to be proficient at performing these procedures since the proficient practitioner is far less likely to injure a patient and is almost certain to reduce the patient's level of discomfort. Becoming proficient in vascular-access procedures requires practice. In fact, the certification and re-certification requirements of some states mandate a minimal number of needle sticks, etc., per year per provider. Historically, medical practitioners practiced needle-based procedures on live volunteers. More recently, simulation techniques and devices have been developed to provide training in vascular-access procedures without the use of live volunteers. U.S. Pat. No. 6,470,302 (“the '302 patent”) surveys the art of medical-simulation devices and also discloses a vascular-access simulation system. The vascular-access simulation system that is disclosed in the '302 patent includes an “interface” device and a computer system. To practice a vascular-access procedure, a user manipulates an “instrument,” referred to in the patent as a “catheter unit assembly,” which extends from the device and serves as a catheter-needle. Potentiometers and encoders within the interface device track the motion and position of the instrument and relay this information to the computer system. The computer system performs a simulation of the surface and subsurface anatomy of human skin, and determines the effect of the instrument's motion on the skin's anatomy. Simulated results are displayed by the computer system. Using the motion information from the interface device, the computer system also generates a control signal that controls a force-feedback system that is coupled to the instrument. The force-feedback system generates various resistive or reactive forces that are intended to simulate the forces that are experienced by a medical practitioner during an actual vascular-access procedure. The user senses these forces during manipulation of the instrument. The simulation system that is disclosed in the '302 patent has many shortcomings that substantially limit its utility as a training or accreditation tool. One shortcoming of that simulation system relates to ergonomics. In particular, when manipulating the catheter-unit assembly of that system, a user's hands are in an awkward and unrealistic position (as compared to the position of the hands during an actual vascular access procedure). This is due, among other reasons, to the height of the interface device, which is a consequence of the layout and design of the mechanisms that compose the interface device. Furthermore, the relative positioning and arrangement of mechanisms with which a user of that system interacts to practice a vascular access procedure is not ergonomic. Specifically, the simulation system enables a user to perform needle “insertion” as well as a “skin-stretch” technique. The skin stretch normally accompanies catheter insertion during an actual procedure to reduce a patient's level of discomfort and to anchor the vein that is being entered. In the system that is disclosed in the '302 patent, the skin-stretch mechanism, which includes a belt—a mock skin—, resides within a casing that is attached to and separate from the housing in which the needle-insertion procedure is practiced. To simulate the skin-stretch technique, a user “stretches” the mock skin. In comparison with an actual procedure, the location at which a user stretches the mock skin is rather remote from the needle “insertion point.” Furthermore, the surface of the mock skin is not co-planar with or at the same height as the needle insertion point. In an actual procedure, of course, they are (i.e., the skin surface is the insertion point). This structural arrangement does nothing to promote a user's “suspension of disbelief” and does not provide a particularly realistic simulation. The inability of prior-art vascular-access simulation systems to realistically simulate a vascular-access procedure limits their usefulness as a training or accreditation tool. SUMMARY The illustrative embodiment of the present invention is a simulation system that provides realistic training and practice for performing vascular-access procedures without using human subjects. Unlike some other prior-art simulation systems, the system is designed to provide ergonomically-correct hand position. The illustrative embodiment of a vascular-access simulator includes a data-processing system and an interface device, referred to herein as a “haptics device.” The haptics device provides the physical interface for performing vascular-access procedures. Some embodiments of the haptics device also provides mechanisms that enable a user to practice certain skin-interaction procedures (i.e., palpation, occlusion and skin stretch). In accordance with the illustrative embodiment, the various mechanisms within the haptics device are configured so that one or more of the following conditions are met: The profile of the haptics device remains relatively low—advantageously not substantially higher than a person's arm when it is resting flat on a surface. The shape of the haptics device is not overtly inconsistent with human anatomy (e.g., an arm, etc.). When practicing a vascular-access procedure using the haptics device, the position of a user's hands is similar to the position of the hands when performing an actual vascular-access procedure. The sites at which the palpation and skin stretch techniques are performed are correct relative to one another (in terms of the sites of these techniques during an actual vascular-access procedure). The sites at which the occlusion and skin stretch techniques are performed are correct relative to one another (in terms of the sites of these techniques during an actual vascular-access procedure). The sites at which the occlusion and skin stretch techniques are performed are correct relative to the site at which the catheter/needle is inserted into the haptics device (in terms of the sites of these techniques during an actual vascular-access procedure). The various mechanisms of the haptics device are beneath the “skin” of the haptics device. Simulators described herein therefore more closely simulate a real vascular-access procedure than simulators in the prior art. This more realistic simulation is expected to result in a more useful training experience. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts vascular-access simulation system 100 in accordance with the illustrative embodiment of the present invention. FIG. 2 depicts functional elements of haptics device 102, which is a part of vascular-access simulation system 100. FIG. 3 depicts a perspective view of haptics device 102. FIG. 4 depicts a perspective view of an illustrative embodiment of an arrangement of various functional modules of haptics device 102. FIG. 5 depicts a top view of the arrangement of FIG. 4. FIG. 6 depicts pseudo skin 220 overlying the arrangement of functional modules of haptics device 102. FIG. 7 depicts an exploded view of haptics device 102. FIG. 8 depicts vascular-access simulation system 100 wherein haptics device 102 is positioned directly in front of monitor 108. DETAILED DESCRIPTION The terms and phrases listed below are defined for use in this specification as follows: “End Effector” means a device, tool or instrument for performing a task. The structure of an end effector depends on the intended task. For example, in the illustrative embodiment, the end effector is intended to be used to simulate a vascular access procedure, and is therefore implemented as a catheter-needle module. Those skilled in the art will recognize that term “end effector” is borrowed from robotics, where it has a somewhat different definition: a device or tool connected to the end of a robot arm. “Imitation” means an artificial likeness that is intended to be substantially similar to an item being imitated; a copy. For example, “imitation skin,” which is used in conjunction with the illustrative embodiment of the present invention, is intended to mimic or copy genuine skin via appropriate selection of color, appearance, feel, and overall presentation. “Mock” means “representative;” a stand-in for a genuine article, but not intended to closely imitate the genuine article. A mock article will never be confused with the genuine article and typically does not promote a suspension of disbelief that the mock article is the genuine article. For example, “mock skin” is not intended to mimic genuine skin, and typically departs from it in terms of color, appearance, feel or overall presentation. “Pseudo” is an inclusive term that means “imitation” or “mock.” For example, pseudo skin is meant to encompass both imitation skin and mock skin. “Skin” means genuine skin. Additional definitions are provided later in this Detailed Description. This Detailed Description continues with an overview of a vascular-access simulator in accordance with the illustrative embodiment. Following the overview, specific embodiments of certain features of the simulator are described in greater detail. Overview The illustrative embodiment of the present invention pertains to a simulation system that provides realistic training and practice for vascular-access procedures without using human subjects. As depicted in FIG. 1, vascular-access simulator 100 includes haptics device 102 and data-processing system 104. Haptics device 102 provides the physical interface for performing any of several simulated vascular-access procedures (e.g., intravenous catherization, central venous line placement, sternal intraosseous insertion, etc.). The term “haptics” (as in “haptics device 102”) relates to touch (i.e., the sense of touch). A fundamental function of haptics device 102, and indeed any haptics interface, is to create a means for communication between users (i.e., humans) and machines. This “communication” is possible since humans are capable of “mechanically” interfacing with their surroundings due, at least in part, to a sense of touch. This “sense of touch” includes sensations of pressure, texture, puncture, thermal properties, softness, wetness, friction-induced phenomena, adhesions, etc. Furthermore, humans also experience vibro-tactile sensations, which include the perception of oscillating objects in contact with the skin and kinesthetic perceptions (i.e., awareness of one's body state, including position, velocity, and forces supplied by the muscles). As will become clear later in this Detailed Description, our ability to perceive a variety of these sensations is exploited by haptics device 102. To the extent that some embodiments of simulator 100 are intended for use as a practice and training tool, it is advantageous for haptics device 102 to simulate vascular-access procedures as realistically as possible and provide a quantitative measure of the user's performance of the simulated procedure. To this end, haptics device 102 possesses one or more of the following attributes, in addition to any others: It possesses sufficient degrees-of-freedom to simulate the relatively free movement of a needle/catheter during an actual vascular-access procedure. It offers the opportunity to perform all steps of a vascular-access procedure, including, for example, needle insertion, skin interactions (e.g., palpation, skin stretch, etc.), catheter threading, etc. It generates appropriate skin- and venous-puncture forces. It measures or otherwise quantifies the effects of user actions on simulated anatomy. It generates appropriate haptic feedback (i.e., feel) during skin-interaction steps. It is configured to provide ergonomically-correct hand position during simulated vascular-access procedures. It is small enough so that it can be positioned in front of a computer monitor so that the haptics device and the monitor are inline with a user's forward-looking field of view. It is at least subtly suggestive of human anatomy and does not present any substantial departures therefrom so as to support a user's ability to suspend disbelief during a simulated vascular-access procedure. Data-processing system 104, which includes processor 106, monitor 108, keyboard 110, mouse 112, and speakers 114, supports the visual aspects of the simulation and other functions described below. Processor 106 is a general-purpose processor that is capable of receiving and processing signals from haptics device 102, running software for the visual portion of the vascular-access simulation including an anatomy simulator, running calibration software for calibrating the various sensing elements used in haptics device 102, and sending control signals to haptics device 102 to support closed-loop force feedback, among other capabilities. Processor 106 comprises memory, in which the software described above is stored. In the illustrative embodiment, processor 106 is a personal computer. Monitor 108 displays a rendering that is generated by processor 106, in conjunction with the above-referenced software. The rendering, which in some embodiments is three-dimensional, is of a region of the body (e.g., isolated arm, thorax, neck, etc.) on which a simulated vascular-access procedure is being performed. The rendering advantageously depicts visual aspects such as, without limitation, the anatomical structures that underlie skin, local deformation of the skin in response to simulated contact, and tracking of a “virtual” instrument (e.g., a needle, etc.) through anatomical structures that underlie the skin. Haptics device 102 is now described in further detail. For pedagogical purposes, haptics device 102 is depicted in FIG. 2 as comprising several functional modules or elements. These include: End effector or Needle/catheter module 218; Pseudo skin 220; Palpation module 222; Skin-stretch module 224; Receiver or Needle-stick module 226; and Electronics/communications interface 228. The functional elements of haptics device 102 listed above that relate to human anatomical features or are otherwise intended to generate resistive forces that would be sensed when penetrating such anatomical features (elements 222-228) are advantageously contained within housing 216 or otherwise located “underneath” pseudo skin 220. In an actual vascular-access procedure, the needle or catheter, of course, remains outside of the body until inserted during the procedure. Likewise, in accordance with the illustrative embodiment, the end effector-needle/catheter module 218-remains outside of housing 216 and pseudo skin 220 until a portion of it is inserted during a simulated vascular-access procedure. Pseudo skin 220 is a membrane that is used in conjunction with the simulation of skin-interaction techniques, such as palpation, occlusion, and skin stretch techniques. Pseudo skin 220 is advantageously, but not necessarily, imitation skin (i.e., skin-like in appearance). In embodiments in which pseudo skin 220 is imitation skin, it possesses any one of a number of natural flesh tones. In some embodiments, pseudo skin 220 is at least somewhat resilient to enable a user to perform skin-interaction techniques. In some embodiments, pseudo skin 220 comprises a thermoplastic elastomer such as Cawiton®, which is available from Wittenburg, B.V., Hoevelaken, Netherlands. The use of imitation skin, as opposed to mock skin, is desirable because it helps a user to “suspend disbelief,” which contributes to making simulator 100 more useful as a training tool. As depicted in FIG. 3, pseudo skin 220 is accessed for insertion and skin-interaction techniques (e.g., palpation, occlusion, skin stretch, etc.) through openings 330 and 332 in housing 216. Opening 330 defines palpation/occlusion region 331 (i.e., the site at which palpation and occlusion techniques are performed) and opening 332 defines skin-stretch region 333 (i.e., the site at which the skin-stretch technique is performed) and includes insertion region 334 for the end effector (e.g., needle/catheter module 218). The ability to perform skin-interaction techniques provides a more realistic simulation of vascular-access procedures. In some embodiments, this ability is provided in conjunction with palpation module 222 and skin-stretch module 224. These modules, and illustrative embodiments thereof, are described in further detail applicant's co-pending U.S. patent application Ser. No. ______ (Atty. Dkt. 115-001). Pseudo skin 220 is disposed adjacent to the inside surface of housing 216 so that it appears to be nearly co-extensive (i.e., co-planar) with housing 216 at openings 330 and 332. This is intended to create a subtle suggestion that the surface of housing 216 is “skin” at regions other than where pseudo-skin 220 is accessed for skin-interaction techniques. Consistent with human anatomy, the remaining functional elements of haptics device 102 (elements 222-228), with the exception of needle/catheter module 218, are “hidden” beneath pseudo skin 220. The end effector (e.g., needle/catheter module 218, etc.) is inserted into haptics device 102 at insertion region 334 at opening 332. During insertion, a user holds handle 336 as desired. In some embodiments, simulator 100 is capable of sensing orientation of the end effector, such as to determine the direction the bevel of a needle or catheter. This is an important aspect of the real insertion technique, since proper bevel orientation reduces a patient's discomfort during needle/catheter insertion. In some embodiments, needle/catheter module 218 is configured to be very similar to a real needle and catheter. Once inserted into haptics device 102, the tip of needle/catheter module 218 engages receiver 226, which, for the illustrative embodiment of a vascular access simulator, is referred to as a “needle-stick module.” Needle-stick module 226 supports the continued “insertion” of the needle/catheter module 218. In particular, in some embodiments, needle-stick module 226 is configured to provide one linear degree of freedom and two rotational degrees of freedom (i.e., pitch and yaw). The linear degree of freedom provides a variable insertion depth, enabling a user to advance needle/catheter module 218 into the “patient's arm” or other body part (i.e., haptics device 102). The rotational degrees of freedom enable a user to move (an engaged) needle/catheter module 218 up or down and left or right. In some embodiments, needle-stick module 226 measures insertion depth, and pitch (up/down) and yaw (left/right) angles. In some embodiments, needle-stick module 226 provides “force feedback” to a user, whereby the user senses a variable resistance during continued advance (insertion) of needle-stick module 218. The resistance is intended to simulate penetration of the skin, a vein, and harder structures such as ligaments, bones, and the like. The resistance advantageously varies with insertion depth and the pitch and yaw of needle/catheter module 218, as described further below. It will be understood that the “measurements” of angle, position, etc. that are obtained by the functional elements described above are obtained in conjunction with various sensors and data-processing system 104. In particular, most of the functional elements described above include one or more sensors. The sensors obtain readings from an associated functional element, wherein the readings are indicative of the rotation, displacement, etc., of some portion of the functional element. These readings provide, therefore, information concerning the manipulation of needle/catheter module 218 in addition to any other parameters. Each sensor generates a signal that is indicative of the reading, and transmits the signal to electronics/communications interface 228. Sensors used in some embodiments include, without limitation, potentiometers, encoders, and MEMS devices. Those skilled in the art will know how to use and appropriately select sensors as a function of their intended use in conjunction with the functional elements described above. Electronics/communications interface 228 receives the signals transmitted by the various functional elements of haptics device 102 and transmits them to data-processing system 104. In some embodiments, as an alternative to transmitting the received signals, electronics/communications interface 228 generates new signal(s) based on the received signals, and transmits the new signals to data-processing system 104. This latter approach requires a substantial increase in processing power and data management (relative to simply transmitting the received signals) and is generally a less-preferred approach. As described later below, electronics/communications interface 228 also receives signals from data processing system 104 and transmits them to needle-stick module 226 as part of a closed loop force-feedback system. Furthermore, electronics/communications interface 228 distributes power to the various functional modules, as required. Data-processing system 104 receives the measurement data and, using the simulation software, calculates the forces that are being applied by the user during the skin-interaction procedures. Furthermore, using an anatomical model, data-processing system 104 calculates the position and angle of a virtual needle within a simulated anatomy (e.g., arm, etc.). Data-processing system 104 displays, on monitor 108, a rendering of the appropriate anatomy (e.g., arm, etc.) and displays and tracks the course of a virtual needle within this anatomy. Furthermore, based on the position and course of the virtual needle (as calculated based on the position and orientation of needle/catheter module 218), data-processing system 104 generates control signals that are transmitted to needle-stick module 226. These control signals vary the resistive force presented by needle-stick module 226 to account for various anatomical structures (e.g., vein, tissue, tendons, bone, etc.) that needle/catheter module 218 encounters, based on the simulation. As a consequence, the resistance to continued needle/catheter insertion that is experienced by a user of simulator 100 is consistent with the resistance that would be sensed by a practitioner during an actual vascular access procedure. In the illustrative embodiment, the functional modules described above are realized as independent, stand-alone mechanisms. In some other embodiments, the functions represented by two or more of these functional modules are combined into an integrated mechanism. Having completed the overview of vascular-access simulator 100 and haptics device 102, the orientation of the various modules relative to one another and their position within housing 216 and relative to pseudo skin 220 will be described in further detail below. It is the inventors' belief that, to the extent a user's interaction with haptics device 102 more closely tracks a practitioner's experience of performing the actual procedure (that the device is designed to simulate), the training experience is more useful. In this regard, the utility of a device such as haptics device 102 is enhanced by a design that is heavily influenced by form-function considerations and ergonomics. And, to that end, the illustrative embodiment of haptics device 102 has been strongly influenced by such considerations. In particular, and as described more fully below, considerations such as the positions of the functional modules (e.g., modules 222, 224, 226, etc.) relative to one another and relative to pseudo skin 220, as well as the shape and dimensions of housing 216 have been taken into account in the design of haptics device 102. Referring now to FIG. 3, housing 216 is defined to have anterior end 338, posterior end 340, lower surface 342, and upper surface 344. Lower surface 342 typically is disposed on a working surface (e.g., table, etc.). In the illustrative embodiment, user interactions with haptics device 102 occur near upper surface 344 of housing 216. In some embodiments, housing 216 is subtly shaped like a portion of a human arm, yet is nondescript enough to avoid creating a discontinuity between what is seen and what is felt. Pseudo skin 220 is accessible through openings 330 and 332 to perform simulated skin interaction techniques and needle/catheter insertion. In the illustrative embodiment, pseudo skin 220 is disposed adjacent to the inside surface of housing 216 so that it appears to be nearly co-extensive (i.e., co-planar) with housing 216 at openings 330 and 332. This is intended to create a subtle suggestion that the surface of housing 216 is “skin” at regions other than where pseudo-skin 220 is accessed. Consistent with human anatomy, the remaining functional elements of haptics device 102 (elements 222-228), with the exception of needle/catheter module 218, are “hidden” beneath pseudo skin 220. In some other embodiments, pseudo skin 220 is simply positioned across openings 330 and 332, and in yet some additional embodiments, the pseudo skin is disposed above the openings. Skin-stretch region 333, which is accessible through opening 332, is proximal to anterior end 338 of housing 216 (relative to palpation/occlusion region 331). Palpation/occlusion region 331, which is accessible through opening 330, is proximal to posterior end 340 of housing 216 (relative to skin-stretch region 333). Insertion region 334, which is accessible through opening 330, is flanked by skin-stretch region 333 toward the anterior end and palpation/occlusion region 331 toward the posterior end. The relative positions at which a user interacts with haptics device 102 to practice these techniques is consistent with their relative positions during an actual vascular-access procedure. That is, a practitioner, sitting in front of a patient, would stretch the patient's skin and then insert the needle/catheter into the skin “behind” (from the practitioner's perspective) the stretch site. Likewise, the occlusion procedure would normally occur “behind” the insertion point. The site at which a practitioner palpates a patient's arm is typically coincident with the insertion point. In the illustrative embodiment of haptics device 102, a user “palpates” pseudo skin 220 “behind” insertion region 334. FIG. 4 depicts a perspective view of an embodiment of some of the functional modules of haptics device 102 and their relative positions within housing 216. Depicted in this Figure are skin-stretch module 224, receiver or needle-stick module 226, palpation module 222, and electronics/communications interface 228. FIG. 5 depicts a top view of these functional modules, FIG. 6 depicts pseudo skin 220 overlying the various functional modules, and FIG. 7 depicts an exploded view showing the various functional modules, pseudo skin 220 and upper and lower portions of housing 216. FIG. 8 depicts haptics device 102 in use in conjunction with data processing system 104. Referring now to FIGS. 4 and 5, skin-stretch module 224, receiver or needle-stick module 226, palpation module 222, and electronics/communications interface 228 are engaged to base 446. The modules that are depicted in FIG. 4 would be oriented within housing 216 (not depicted in FIG. 4) such that skin-stretch module 224 is proximal to anterior end 338 of housing 216 and electronics/communications interface 228 is proximal to posterior end 340 of housing 216. The electrical interconnections between electronics/communications interface 228 and the other functional modules, as described earlier in this specification, can be seen in FIGS. 4 and 5. The relative position of specific functional modules within housing 216 is consistent with the sites at upper surface 344 at which a user accesses those functions. In particular, skin-stretch module 224 is proximal to anterior end 338 of the housing relative to palpation module 222 and relative to at least the portion of receiver module 226 that receives needle/catheter module 218. Likewise, palpation module 222 is proximal to posterior end 340 of the housing relative to skin-stretch module 224 and relative to the portion of receiver module 226 that receives needle/catheter module 218. The portion of receiver module 226 that receives needle/catheter module 218 is flanked by skin-stretch module 224 toward anterior end 338 and by palpation module 222 toward posterior end 340. In the illustrative embodiment, a portion of receiver module 226 is disposed in an open region between standoffs of palpation module 222. If receiver module 226 were not disposed in this region, then either the length or the height of housing 216 would have to be increased. It is undesirable to increase the length because doing so would further separate the sites at upper surface 344 at which a user practices the various techniques. In particular, the palpation site would be rather remote from the needle insertion point. In an actual vascular-access procedure, these sites, of course, are virtually coincident. It is undesirable to increase the height of the housing because, if placed in front of a monitor on which the visual portion of the simulation is being displayed, the housing will obscure the view. Furthermore, the greater height can force the hands into an unrealistic position in terms of the procedure being practiced. This design constraint biased the design of palpation module 222 toward one in which standoffs are used to elevate the palpation module to recover space that might otherwise be lost. And this prompted the use of two actuating devices, rather than one, as could have otherwise been used. Electronics/communications interface 228 is vertically oriented such that its major surface is oriented orthogonal to the uppermost surface of palpation module 222. It is advantageous to orient interface 228 in this manner since it reduces the length of housing 216 (as compared to orienting the interface with its major surface parallel to the uppermost surface of palpation module 222). And orienting interface 228 in this manner does not affect the height of housing 216 since, in this orientation, the interface is no higher than the uppermost surface of palpation module 222. Arranging the functional modules as described above; that is, in a generally horizontal arrangement rather than in a vertical arrangement, enables the use of a relatively low-profile housing for haptics unit 102. This is desirable because it facilitates positioning housing 216 in front of a computer display without obscuring any portion of the screen, as is depicted in FIG. 8. FIG. 8 depicts simulator 100, which comprises data processing system 104 (including processor 106, monitor 108, keyboard 110, mouse 112) and haptics device 102 (including housing 216 and the internal functional modules and end effector 218). As depicted in FIG. 8, haptics device 102 and monitor 108 are inline with a user's forward-looking field of view. This is desirable since a user looks to the monitor to view the visual portion of the simulation. (See, e.g., applicant's co-pending U.S. patent application Ser. No. ______ (Atty. Dkt. 115-005). To the extent that the user interfaces with haptics device 102 at a location that is not directly in front of monitor 108, there is an inconsistency that does not promote a “suspension of disbelief” on the part of the user. To ensure that haptics device 102 does not obscure any portion of the screen, the functional modules are dimensioned and arranged so that the top of housing 216 advantageously has a height that is no more than about 5 inches, and more preferably has a height of about 4 inches or less. As previously described, the various functional modules of haptics device 102, with the exception of needle/catheter module 218, are disposed beneath pseudo skin 220. This is, of course, consistent with the experience of performing a vascular access procedure. That is, the interactions occur at the skin. In the illustrative embodiment, the end effector (e.g., needle/catheter module 218, etc.) is inserted at insertion region 334 through opening 648 in pseudo skin 220. Furthermore, arranging the functional modules as described above, and beneath pseudo skin 220, results in the correct hand position for a user of haptics device 102, with reference to an actual vascular-access procedure. FIG. 7 depicts an exploded view of haptics device 102 showing the relative positioning of the various functional modules within housing 216. In particular, FIG. 7 depicts lower portion 750 of housing 216, base 446, skin-stretch module 224, receiver module 226, palpation module 222, electronics/communications interface 228, pseudo skin 220, and upper portion 752 of housing 216. It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this specification, numerous specific details are provided in order provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc. Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents. | <SOH> BACKGROUND OF THE INVENTION <EOH>Medical practitioners, such as military medics, civilian emergency-medical personnel, nurses, and physicians, routinely perform vascular-access procedures (e.g., IV insertion, central venous-line placement, peripherally-inserted central catheter, etc). It is desirable for a practitioner to be proficient at performing these procedures since the proficient practitioner is far less likely to injure a patient and is almost certain to reduce the patient's level of discomfort. Becoming proficient in vascular-access procedures requires practice. In fact, the certification and re-certification requirements of some states mandate a minimal number of needle sticks, etc., per year per provider. Historically, medical practitioners practiced needle-based procedures on live volunteers. More recently, simulation techniques and devices have been developed to provide training in vascular-access procedures without the use of live volunteers. U.S. Pat. No. 6,470,302 (“the '302 patent”) surveys the art of medical-simulation devices and also discloses a vascular-access simulation system. The vascular-access simulation system that is disclosed in the '302 patent includes an “interface” device and a computer system. To practice a vascular-access procedure, a user manipulates an “instrument,” referred to in the patent as a “catheter unit assembly,” which extends from the device and serves as a catheter-needle. Potentiometers and encoders within the interface device track the motion and position of the instrument and relay this information to the computer system. The computer system performs a simulation of the surface and subsurface anatomy of human skin, and determines the effect of the instrument's motion on the skin's anatomy. Simulated results are displayed by the computer system. Using the motion information from the interface device, the computer system also generates a control signal that controls a force-feedback system that is coupled to the instrument. The force-feedback system generates various resistive or reactive forces that are intended to simulate the forces that are experienced by a medical practitioner during an actual vascular-access procedure. The user senses these forces during manipulation of the instrument. The simulation system that is disclosed in the '302 patent has many shortcomings that substantially limit its utility as a training or accreditation tool. One shortcoming of that simulation system relates to ergonomics. In particular, when manipulating the catheter-unit assembly of that system, a user's hands are in an awkward and unrealistic position (as compared to the position of the hands during an actual vascular access procedure). This is due, among other reasons, to the height of the interface device, which is a consequence of the layout and design of the mechanisms that compose the interface device. Furthermore, the relative positioning and arrangement of mechanisms with which a user of that system interacts to practice a vascular access procedure is not ergonomic. Specifically, the simulation system enables a user to perform needle “insertion” as well as a “skin-stretch” technique. The skin stretch normally accompanies catheter insertion during an actual procedure to reduce a patient's level of discomfort and to anchor the vein that is being entered. In the system that is disclosed in the '302 patent, the skin-stretch mechanism, which includes a belt—a mock skin—, resides within a casing that is attached to and separate from the housing in which the needle-insertion procedure is practiced. To simulate the skin-stretch technique, a user “stretches” the mock skin. In comparison with an actual procedure, the location at which a user stretches the mock skin is rather remote from the needle “insertion point.” Furthermore, the surface of the mock skin is not co-planar with or at the same height as the needle insertion point. In an actual procedure, of course, they are (i.e., the skin surface is the insertion point). This structural arrangement does nothing to promote a user's “suspension of disbelief” and does not provide a particularly realistic simulation. The inability of prior-art vascular-access simulation systems to realistically simulate a vascular-access procedure limits their usefulness as a training or accreditation tool. | <SOH> SUMMARY <EOH>The illustrative embodiment of the present invention is a simulation system that provides realistic training and practice for performing vascular-access procedures without using human subjects. Unlike some other prior-art simulation systems, the system is designed to provide ergonomically-correct hand position. The illustrative embodiment of a vascular-access simulator includes a data-processing system and an interface device, referred to herein as a “haptics device.” The haptics device provides the physical interface for performing vascular-access procedures. Some embodiments of the haptics device also provides mechanisms that enable a user to practice certain skin-interaction procedures (i.e., palpation, occlusion and skin stretch). In accordance with the illustrative embodiment, the various mechanisms within the haptics device are configured so that one or more of the following conditions are met: The profile of the haptics device remains relatively low—advantageously not substantially higher than a person's arm when it is resting flat on a surface. The shape of the haptics device is not overtly inconsistent with human anatomy (e.g., an arm, etc.). When practicing a vascular-access procedure using the haptics device, the position of a user's hands is similar to the position of the hands when performing an actual vascular-access procedure. The sites at which the palpation and skin stretch techniques are performed are correct relative to one another (in terms of the sites of these techniques during an actual vascular-access procedure). The sites at which the occlusion and skin stretch techniques are performed are correct relative to one another (in terms of the sites of these techniques during an actual vascular-access procedure). The sites at which the occlusion and skin stretch techniques are performed are correct relative to the site at which the catheter/needle is inserted into the haptics device (in terms of the sites of these techniques during an actual vascular-access procedure). The various mechanisms of the haptics device are beneath the “skin” of the haptics device. Simulators described herein therefore more closely simulate a real vascular-access procedure than simulators in the prior art. This more realistic simulation is expected to result in a more useful training experience. | 20040323 | 20130326 | 20050929 | 73072.0 | 1 | FRISBY, KESHA | Vascular-access simulation system with ergonomic features | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,325 | ACCEPTED | Vehicle seat with rollover safety features | This invention is vehicle seat, which provides enhanced occupant protection in the event of a vehicle rollover. The seat includes a rollover sensor and mechanisms compatible with power-adjustable seat design, that cause rapid distancing of the occupant from the vehicle roof in the event of a rollover. The mechanisms include high-speed motors operating reclining, lateral position, and seat lowering mechanisms, as well as pyro actuators for these mechanisms. | 1. a seat for a vehicle, comprising: a seat back, a seat cushion means for power adjustment of the seat, comprising at least one motor coupled to the seat, and: a rollover sensor, wherein the motor(s) operates at a low speed during normal operation, and at a very high speed in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition. 2. The seat of claim 1, wherein the power adjustment means is at least one of: seat recliner wherein at least one of the seat cushion and back is reclined rearward rapidly by a motor in response to the signal from the rollover sensor, a seat height adjuster wherein the seat is lowered rapidly by a motor in response to the signal from the rollover sensor, or a seat position adjuster wherein the seat is moved either forward or backward relative to the front of the car rapidly by a motor in response to the signal from the rollover sensor. 3. The seat of claim 2, further comprising: a seat position adjuster wherein the seat is moved in a side-to-side direction relative to the front of the car rapidly by a motor in response to the signal from the rollover sensor. 4. The seat of claim 2 or 3, further comprising: compression of at least one of the seat back and seat cushion in response to a signal from the rollover sensor indicating the vehicle is a rollover condition. 5. The seat of claim 1, further comprising an integrated safety belt, with a pre-tensioner, wherein the pre-tensioner is triggered in response to a signal from the roll-over sensor. 6. The seat of claim 4, comprising: mechanisms that sense the position of the seat, and a system to maximize the safety of a seat occupant by determining, from the position of the seat and the vehicle configuration, the optimum sequence, direction and magnitude of seat motions in response to the rollover signal. 7. The seat of claim 6, wherein the seat further comprise sensing of at least one of the weight or size of the occupant. 8. a seat for a vehicle, comprising: a seat back, a seat cushion means for power adjustment of the seat for the seat, comprising at least one motor coupled to the seat, and: a rollover sensor, wherein the motor(s) operates at a low speed during normal operation, and at a very high speed in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition, means for compressing at least one of the seat back and seat cushion in response to a signal from the rollover sensor indicating the vehicle is a rollover condition, and: an integrated safety belt with pre-tensioner 9. The seat of claim 9, wherein the power adjustment means is at least one of: seat recliner wherein at least one of the seat back and cushion is reclined rearward rapidly by a motor in response to the signal from the rollover sensor, a seat height adjuster wherein the seat is lowered rapidly by a motor in response to the signal from the rollover sensor, or a seat adjuster wherein the seat is moved forward or backward relative to the front of the car rapidly by a motor in response to the signal from the rollover sensor. 10. The seat of claim 10, further comprising a seat position adjuster wherein the seat is moved side-to-side relative to the front of the car rapidly by a motor in response to the signal from the rollover sensor. 11. a seat for a vehicle, comprising: a seat back, a seat cushion means for power adjustment of the seat for the seat, comprising at least one motor coupled to the seat, a rollover sensor, and: a pyro actuator disposed between the motor and the seat, wherein, in response to a signal from the rollover sensor, the pyro actuator fires and pushes the seat such as to cause very rapid movement of at least one of the seat back and seat cushion. 12. The seat of claim 11 wherein the movement is reclining. | RELATED APPLICATIONS Not Applicable FEDERALLY SPONSORED RESEARCH Not Applicable SEQUENCE LISTING Not Applicable BACKGROUND OF THE INVENTION The invention relates to vehicle seats, particularly seats for automobiles and light trucks. The seats of this invention will provide increased occupant protection in the event of a rollover accident. Rollover accidents occur relatively slowly compared to other accidents, such as front, side, or rear impacts. Thus rollover accidents require a different response compared to conventional impact restraint systems to achieve occupant protection. Rollover occupant protection system design involves the integration of a number of components in the vehicle which must be compatible with each other. One element of the vehicle available to vehicle designers in developing effective rollover occupant protection system designs is the seat with integral restraint. One element of the vehicle that is particularly hazardous to restrained occupants is the intruding roof. This invention moves the occupant's head away from the vehicle roof automatically during a rollover. It has been known in the art for some time, recognized by the inventors for almost ten years, that an important tool available to designers of occupant safety in a rollover, along with, for example, stronger roof structures, better occupant packaging, more effective restraint systems, active or passive rollbars and other available technology, is to dynamically move the occupant away from the roof before the roof crushes. In large vehicles such as truck cabs, there is room to move the entire seat straight down a large distance away from the roof, and several approaches for this problem have been proposed. Three concepts for accomplishing rollover protection in light passenger vehicles with power (electric) integrated seats (all-belts to seats) are identified: dynamically tilt the seat back rearward in order to effectively move the occupants head away from the roof and rearward in the vehicle, reorienting the torso-head/neck complex to a more advantageous orientation; compress the seat back and seat cushion to be smaller than their normal dimensions to increase headroom in conjunction with rollover actuated pretensioning seatbelts; under certain circumstances move the seat cushion forward or rearward or laterally to better position the occupant relative to the roof structure and/or to allow for the downward deployment of the seat back in restricted compartment space conditions Although solutions to some of the concepts have been previously proposed, none have been implemented in light vehicles to date. The inventors believe that the reason for the lack of implementation in production power-adjustable integrated seats is that the proposed solutions do not address the requirements of powered integrated seats. The earlier proposed solutions are not compatible with the integrated, power-adjustable seats found increasingly, for example, on light passenger vehicles. In order to make these features available, innovative solutions, that are workable and usable on modern, powered seats, must be employed. This invention provides greatly increased protection to vehicle occupants in a rollover accident by providing novel safety mechanisms that are usable in existing power-adjustable seats. BRIEF SUMMARY OF THE INVENTION The invention provides for increased safety of vehicle occupants in the event of a rollover accident. Parts of the invention, unlike previous solutions, are actually capable of being implemented or retrofitted into real, current, power-adjustable seat designs. In addition, other parts are applicable to electric and non-electric seat designs. The invention provides a seat for a vehicle, comprising a seat back, a seat cushion, and means for power adjustment for the seat. The adjustment mechanism comprises at least one motor, or one slow burn pyrotechnic actuator coupled to the seat. Relevant types of adjustment means include seat reclining, seat height adjustment, and seat position relative to the front of the car. The seat further comprises a rollover sensor. The motor operates at a low speed during normal operation, and at a very high speed in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition, requiring activation. Thus the seat is reclined rearward rapidly, lowered rapidly, moved forward/backward rapidly, side-to-side rapidly, or any and all combinations, when the rollover sensor triggers the high speed operation of the motor(s). The invention also provides for a vehicle seat, which includes means for compressing and/or translating at least one of the seat back and seat cushions in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition. It is to be understood that the concepts described above need not be all implemented in a given vehicle seat design, but that the optimum safety will be achieved if all work together in response to the rollover sensor signal, along with an integrated safety belt with a pretensioner, the pretensioner also being activated by the rollover signal. The inventor's contemplate that the best use of the invention is to integrate all of the protection mechanisms that are applicable in one seat design. BRIEF DESCRIPTION OF THE DRAWINGS The detailed description of how to make and use the invention will be facilitated by referring to the accompanying drawings. FIG. 1 depicts the major elements of the vehicle seat relative to the invention. FIG. 2 shows in block diagram form the operation of the invention FIG. 3a, b, and c illustrate the resultant movements of the seat in response to the rollover signal FIG. 4 shows an alternate embodiment of the invention DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the seat consists of a back, 1, and a cushion 2. The invention is intended to be compatible with power-adjustable seats. A wide variety of power seat designs exist, most of which are compatible with the invention. Accordingly, the components of the seat are shown in a very general form, and it is understood that the details of a particular seat design are not critical to the invention. The exemplary elements shown include a recliner motor 5, which is coupled to a rotatable member, 3, such that the motor causes either the seat back, 1, or the entire seat, depending on the design, to rotate. The seat may also include a height adjustment mechanism, shown as a motor, 7 coupled to the seat at member, 4, and a lateral adjustment mechanism, consisting of a motor, 6, coupled to the seat through member, 4. The exact make up of the couplings, and number and orientation of motors is not essential to the operation of the invention. A skilled designer of such seats will understand how to apply the invention to a particular seat design from this disclosure. Conventional adjustment mechanism designs use motors capable of moving the seat at rates that are typically quite slow. Thus the motors in existing power seat designs are specified to achieve adequate performance for adjustment operation, but are not capable of moving the seat fast enough to be effective for rollover safety. A typical motor for a power seat uses 50 watts for motion. The invention requires a rollover sensor in the vehicle, typically integrated with the seat. Rollover sensor designs exist in the art, which are suitable for use with the invention. For purposes of implementing the invention, a particular rollover detector sensor may be used as long as the sensor is capable of discriminating between normal operation, and a wide enough range of roll conditions to ensure that a signal indicating immediate rollover will not be generated other than during a real rollover event. The action of the invention will make it difficult for the vehicle operator to maintain control of the vehicle, and must not be deployed unless the vehicle is truly rolling over. The invention uses a special motor that is capable of, for at least one time period, of operating at a much higher speed than that required for normal adjustment functionality. Referring to FIG. 2, the rollover sensor, 8, with suitable electronics, 9, will generate a signal indicating that the vehicle is irretrievably in the process of rolling over. The rollover signal may cause multiple events to take place. The invention includes any combination of these events. One event is that a very high power drive signal, 10, is applied to the recliner motor, 5, causing the seat to recline rearward at a rate at least 50 deg/s, preferably 100 deg/s, much faster than normal seat adjustment rates. This higher speed is sufficient to recline the seat nominally within 0.25-0.5 seconds, well within the 2-6 seconds of time typical in a rollover scenario. A tested, suitable motor, which is compatible with existing recliner designs, yet capable of at least one high speed recline, is based on a high magnetic strength dc motor. This samarium cobalt magnet motor is a close outline and mounting match for an existing conventional seat motor. It should be appreciated, that it is acceptable for the motor to require replacement after a rollover accident, similar to airbags requiring replacement after deployment. Such a high performance motor can typically accept 1500 watts for the short run duration and for much higher motion speed than normal power seat adjustment. A suitable motor for this invention need only operate reliably at the high rate for one cycle. A typical samarium cobalt dc motor requires only 500 to 1000 J of electrical energy for this one time seatback motion (rotation). The electrical energy is provided by either the car battery, a close proximity energy supply such as a high energy density capacitor, or a small onboard battery. Similarly, high power signals, 12 and 13 may be applied to the height, longitudinal and lateral adjustment motors, 6 and 7, if such motors are available in a particular seat design. Thus the seat may be rapidly rotated, lowered, and optimally positioned longitudinally. The result is that well before the roof crushes substantially into the occupant space, the occupant's head and chest will have been moved significantly farther from the roof. The addition of the rollover sensor, electronics and suitable motors is fully compatible with existing power seat designs. The inventors have successfully retrofitted an existing seat with the sensor, electronics and high power motors and drivers. It is understood that any combination of these actions are considered by the invention, but optimally all three should be employed. The invention is also best implemented in combination with a seat belt, integrated with the seat. The seat belt should have at least one pretensioner, 13, known in the art, which is also triggered by the rollover signal. The separate operation of these actions is illustrated in FIG. 3a, b and c. It is understood, that the electronics may sequence these actions appropriately, for instance compress the cushions, tension the belt, and move the seat cushion to the right position before fully reclining the seat. Many existing power adjustable seat designs already have mechanisms that perform some or all of the three above-mentioned adjustments, recline, raise/lower, or position forward/backward. In almost all vehicles, lowering the seat and reclining it backward will have advantageous effect in a rollover accident. Depending on the layout of the vehicle, positioning the seat forward or backward may allow for more recline or lowering action. Thus the invention includes the possibility of moving the seat forward/backward in response to the rollover signal as well. It is to be understood that replacing the conventional motors with physically compatible designs capable of very high power operation, along with the suitable sensor and control electronics, allows for effective rollover protection to be added with little redesign of the vehicle, or even retrofitted to existing vehicles. For some vehicles, moving the seat side-to-side may also allow for greater lowering/reclining. Also, depending on the nature of the rest of the rollover occupant protection system there may be safety benefit to be obtained in a rollover from moving the occupant away from the window or door. Thus a fourth movement, side-to-side, may increase occupant protection as well. The inventors know of no existing light vehicle seats that include such lateral positioning. However, for new vehicle design, a fourth movement axis, side-to-side lateral, may be designed in. The lateral positioning will also occur in response to the rollover signal, sequenced appropriately, for the specific vehicle configuration. The inventors contemplate that a motor drive, pyro actuator or other actuator of types known in the art may be employed in a side-to-side seat positioning mechanism. For all of the above-mentioned motions, it may be advantageous to sense the current seat position before determining the sequence and nature of the rollover response movements. Depending on the seat position at the time of rollover and the shape of the vehicle interior, the direction and magnitude of positioning that will allow maximum recline/lowering may vary. Thus the invention may further include the capability of sensing current seat position, and possibly occupant size and/or weight, and determining the optimum magnitude, direction, and sequence of motions to result in the greatest possible clearance between the occupant's head and chest from the roof. Smart safety systems that sense occupant characteristics and shape the restraint response accordingly have been developed to protect smaller occupants from airbags. Also systems that measure seat position and remember it for operator convenience also exist. The invention may employ these devices for the rollover scenario, in many cases with little modification other than programming. Of course new, ground-up sensing and sequencing designs, used in conjunction with the invention, are also contemplated. Other safety mechanisms, 14, such as airbag restraint devices and sideflaps may be triggered by the rollover signal. Of particular relevance to the invention is a mechanism for compressing the seat bottom cushion and/or seat back cushion. The occupant may be further distanced from the roof, by compressing the seat back and/or cushion. It is to be appreciated that the seat back and cushion thickness can be several inches, so compressing the thickness can easily result in gaining a few inches of head clearance, which can greatly mitigate any trauma occurring from a crushed roof. Various compression means have been proposed. One means consists of using cables or wires actuated by an explosive tensioner, such as used in seat-belt tensioners, familiar in the art. The tensioner is fired by the signal from the rollover sensor. The wire or cables are wrapped around pulleys, and pull the seat structure closer to the seat frame, when the tensioner fires and rapidly rolls up the cable. Such compression mechanisms are compatible with this invention. Other novel compression mechanisms are contemplated by the inventors and are intended to be the subject of a separate patent application. Another embodiment of the invention is shown in FIG. 4. The high power motor implementations described above have the advantage that they require the least seat re-design, and offer the maximum flexibility in terms of allowing for precisely tailored sequencing of seat motion. The inventors contemplate an alternative approach that is still compatible with powered seats. In FIG. 4, a pyro actuator is mounted in series with the recliner drive train. This pyro actuator is preferably of the slow burn variety, used in other automotive applications. In normal operation, the motor 5 operates the drive train normally. When fired by the rollover sensor, the pyro actuator extends or retracts relative to the rotatable member 3 causing the seat to recline rapidly, typically about 30 degrees in 0.25-0.5 second. The same approach may be employed in the other motions as well as for reclining. Such a mechanism, coupled with a seat cushion compressor would produce a significant benefit and is very desirable. | <SOH> BACKGROUND OF THE INVENTION <EOH>The invention relates to vehicle seats, particularly seats for automobiles and light trucks. The seats of this invention will provide increased occupant protection in the event of a rollover accident. Rollover accidents occur relatively slowly compared to other accidents, such as front, side, or rear impacts. Thus rollover accidents require a different response compared to conventional impact restraint systems to achieve occupant protection. Rollover occupant protection system design involves the integration of a number of components in the vehicle which must be compatible with each other. One element of the vehicle available to vehicle designers in developing effective rollover occupant protection system designs is the seat with integral restraint. One element of the vehicle that is particularly hazardous to restrained occupants is the intruding roof. This invention moves the occupant's head away from the vehicle roof automatically during a rollover. It has been known in the art for some time, recognized by the inventors for almost ten years, that an important tool available to designers of occupant safety in a rollover, along with, for example, stronger roof structures, better occupant packaging, more effective restraint systems, active or passive rollbars and other available technology, is to dynamically move the occupant away from the roof before the roof crushes. In large vehicles such as truck cabs, there is room to move the entire seat straight down a large distance away from the roof, and several approaches for this problem have been proposed. Three concepts for accomplishing rollover protection in light passenger vehicles with power (electric) integrated seats (all-belts to seats) are identified: dynamically tilt the seat back rearward in order to effectively move the occupants head away from the roof and rearward in the vehicle, reorienting the torso-head/neck complex to a more advantageous orientation; compress the seat back and seat cushion to be smaller than their normal dimensions to increase headroom in conjunction with rollover actuated pretensioning seatbelts; under certain circumstances move the seat cushion forward or rearward or laterally to better position the occupant relative to the roof structure and/or to allow for the downward deployment of the seat back in restricted compartment space conditions Although solutions to some of the concepts have been previously proposed, none have been implemented in light vehicles to date. The inventors believe that the reason for the lack of implementation in production power-adjustable integrated seats is that the proposed solutions do not address the requirements of powered integrated seats. The earlier proposed solutions are not compatible with the integrated, power-adjustable seats found increasingly, for example, on light passenger vehicles. In order to make these features available, innovative solutions, that are workable and usable on modern, powered seats, must be employed. This invention provides greatly increased protection to vehicle occupants in a rollover accident by providing novel safety mechanisms that are usable in existing power-adjustable seats. | <SOH> BRIEF SUMMARY OF THE INVENTION <EOH>The invention provides for increased safety of vehicle occupants in the event of a rollover accident. Parts of the invention, unlike previous solutions, are actually capable of being implemented or retrofitted into real, current, power-adjustable seat designs. In addition, other parts are applicable to electric and non-electric seat designs. The invention provides a seat for a vehicle, comprising a seat back, a seat cushion, and means for power adjustment for the seat. The adjustment mechanism comprises at least one motor, or one slow burn pyrotechnic actuator coupled to the seat. Relevant types of adjustment means include seat reclining, seat height adjustment, and seat position relative to the front of the car. The seat further comprises a rollover sensor. The motor operates at a low speed during normal operation, and at a very high speed in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition, requiring activation. Thus the seat is reclined rearward rapidly, lowered rapidly, moved forward/backward rapidly, side-to-side rapidly, or any and all combinations, when the rollover sensor triggers the high speed operation of the motor(s). The invention also provides for a vehicle seat, which includes means for compressing and/or translating at least one of the seat back and seat cushions in response to a signal from the rollover sensor indicating the vehicle is in a rollover condition. It is to be understood that the concepts described above need not be all implemented in a given vehicle seat design, but that the optimum safety will be achieved if all work together in response to the rollover sensor signal, along with an integrated safety belt with a pretensioner, the pretensioner also being activated by the rollover signal. The inventor's contemplate that the best use of the invention is to integrate all of the protection mechanisms that are applicable in one seat design. | 20040324 | 20071009 | 20050929 | 94888.0 | 0 | ABRAHAM, TANIA | VEHICLE SEAT WITH ROLLOVER SAFETY FEATURES | SMALL | 0 | ACCEPTED | 2,004 |
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10,807,448 | ACCEPTED | Multi-axis installable and adjustable level | The present multi-axis installable and adjustable level is permanently installed to a suitable panel on or in a movable structure, such as a recreational vehicle or the like, or a portable work table or the like. The present level enables a user of the structure to level the structure precisely as required, and/or to determine the level of the structure, once the present level has been properly installed. The present level comprises a pair of leaves or panels which are hinged together, with one of the leaves providing coarsely adjustable permanent attachment to the structure and the opposite leaf including a bull's eye type level thereon. The first leaf is secured to a suitable panel (which may be sloped, horizontal, or vertical) of the structure, and the second leaf is extended and locked in a substantially horizontal orientation. The bubble level is then leveled precisely using the infinitesimal adjustment provided. | 1. A multi-axis installable and adjustable level, comprising: a permanent attachment leaf having a plurality of attachment holes therethrough; a level display leaf; an omnidirectional level display disposed upon said level display leaf; a plurality of coarse adjustment hinge lugs adjustably interconnecting said permanent attachment leaf to said level display leaf, said plurality of coarse adjustment hinge lugs of each said leaf includes a plurality of mutually mating faces and a plurality of radially disposed hinge lug position locking teeth disposed on each of said mating faces; and a hinge bolt passing through said coarse adjustment hinge lugs; wherein said plurality of radially disposed hinge lug position locking teeth selectively lock said leaves immovably together when said hinge bolt is tightened. 2. (canceled) 3. The multi-axis installable and adjustable level according to claim 1, further including an infinitesimally and omnidirectionally adjustable level display mechanism disposed between said level display leaf and said omnidirectional level display. 4. The multi-axis installable and adjustable level according to claim 3, wherein said infinitesimally and omnidirectionally adjustable level display mechanism further comprises: an omnidirectional level display mounting plate having a periphery with a plurality of level adjustment screw holes; said level display leaf having a level display mounting plate seat with a plurality of threaded level display adjustment screw receptacles disposed therein, corresponding in number to said level display adjustment screw holes of said omnidirectional level display mounting plate; a plurality of omnidirectional level display adjustment screws disposed through said level display adjustment screw holes of said omnidirectional level display mounting plate and said threaded level display adjustment screw receptacles of said level display leaf; and a level display position-holding compression spring disposed between said level display leaf and said omnidirectional level display mounting plate. 5. The multi-axis installable and adjustable level according to claim 1, wherein said omnidirectional level display is a bull's eye level. 6. The multi-axis installable and adjustable level according to claim 1, wherein at least said permanent attachment leaf and said level display leaf are formed of materials selected from the group consisting of metal and plastic. 7. The multi-axis installable and adjustable level according to claim 1, wherein said attachment holes of said permanent attachment leaf comprise: a single round fastener hole; and two coarse adjustment mounting holes disposed upon a fastener circle defined by said single round fastener hole, with said coarse adjustment mounting holes comprising arcuate slots disposed upon said fastener circle and aligned therewith. 8. The multi-axis installable and adjustable level according to claim 1, further including: a pair of mutually opposed edges extending from said permanent attachment leaf, and normal thereto; and a plurality of peripheral edges depending from said level display leaf, with one of said peripheral edges of said level display leaf contacting a respective one of said mutually opposed edges of said permanent attachment leaf when said permanent attachment leaf and said level display leaf are folded together, thereby placing each said leaf parallel to one another. 9. The multi-axis installable and adjustable level according to claim 1, further including: a stop block extending from said level display leaf; and an adjustable mechanical stop adjustably abutting said stop block and stopping further angular extension of said level display leaf when said mechanical stop is properly adjusted and said level display leaf is leveled. 10. The multi-axis installable and adjustable level according to claim 1, further including: a fixed alignment mark disposed upon said level display leaf; and an adjustable alignment mark adjustably aligned with said fixed alignment mark and indicating proper angular extension of said level display leaf when said adjustable alignment mark is properly adjusted and said level display leaf is leveled. 11. A multi-axis installable and adjustable level, comprising: a permanent attachment leaf having a plurality of attachment holes therethrough; a level display leaf extending from said permanent attachment leaf; an omnidirectional level display disposed upon said level display leaf; and an infinitesimally and omnidirectionally adjustable level display mechanism disposed between said level display leaf and said omnidirectional level display, wherein said infinitesimally and omnidirectionally adjustable level display mechanism further comprises: an omnidirectional level display mounting plate having a periphery with a plurality of level adjustment screw holes; said level display leaf having a level display mounting plate seat with a plurality of threaded level display adjustment screw receptacles disposed therein, corresponding in number to said level display adjustment screw holes of said omnidirectional level display mounting plate; a plurality of omnidirectional level display adjustment screws disposed through said level display adjustment screw holes of said omnidirectional level display mounting plate and said threaded level display adjustment screw receptacles of said level display leaf; and a level display position-holding compression spring disposed between said level display leaf and said omnidirectional level display mounting plate. 12. The multi-axis installable and adjustable level according to claim 11, further including a plurality of coarse adjustment hinge lugs adjustably interconnecting each said leaf together; and a hinge bolt passing through said hinge lugs and selectively locking each said immovably together. 13. The multi-axis installable and adjustable level according to claim 12, wherein said plurality of coarse adjustment hinge lugs of each said leaf further includes: a plurality of mutually mating faces; and a plurality of radially disposed hinge lug position locking teeth disposed upon each of said mating faces, locking said coarse adjustment hinge lugs immovably together when said hinge bolt is tightened. 14. (canceled) 15. The multi-axis installable and adjustable level according to claim 11, wherein said omnidirectional level display is a bull's eye level. 16. The multi-axis installable and adjustable level according to claim 11, wherein at least said permanent attachment leaf and said level display leaf are formed of materials selected from the group consisting of metal and plastic. 17. The multi-axis installable and adjustable level according to claim 11, wherein said attachment holes of said permanent attachment leaf comprise: a single round fastener hole; and two coarse adjustment mounting holes disposed upon a fastener circle defined by said single round fastener hole, with said coarse adjustment mounting holes comprising arcuate slots disposed upon said fastener circle and aligned therewith. 18. The multi-axis installable and adjustable level according to claim 11, further including: a pair of mutually opposed edges extending from said permanent attachment leaf, and normal thereto; and a plurality of peripheral edges depending from said level display leaf, with one of said peripheral edges of said level display leaf contacting a respective one of said mutually opposed edges of said permanent attachment leaf when said permanent attachment leaf and said level display leaf are folded together, thereby placing each said leaf parallel to one another. 19. The multi-axis installable and adjustable level according to claim 11, further including: a stop block extending from said level display leaf; and an adjustable mechanical stop adjustably abutting said stop block and stopping further angular extension of said level display leaf when said mechanical stop is properly adjusted and said level display leaf is leveled. 20. The multi-axis installable and adjustable level according to claim 11, further including: a fixed alignment mark disposed upon said level display leaf; and an adjustable alignment mark adjustably aligned with said fixed alignment mark and indicating proper angular extension of said level display leaf when said adjustable alignment mark is properly adjusted and said level display leaf is leveled. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to indicating devices for displaying a level line or plane, and more specifically to a leveling device which is permanently installed and adjusted on or in a movable structure, whereupon the structure may be accurately leveled by means of the present leveling device. The present level includes a two way adjustable base and an infinitesimally adjustable “bull's eye” type bubble level vial, whereby the device may be finely adjusted after installation to provide a level reference whenever the structure to which it is secured is moved. 2. Description of the Related Art There are innumerable portable structures which require at least a close approximation of a level attitude when they are relocated periodically. Examples of such are motor homes, house trailers, and camper type vehicles. Oftentimes, a craftsman must erect a work table or the like, which requires a level attitude for accurate work. The conventional technique nearly universally used for leveling such structures is to place a level (e.g., linear or bull's eye level, electronic leveling device, etc.) temporarily on or across a surface of the structure desired to be leveled, adjust the structure until it is level according to the level instrument, and remove the instrument from the structure. The problem with this technique is that the portable level must be repositioned on or in the structure, each time it is necessary to level the structure. In those cases where a linear level is used, the level must be repositioned at least once, normal to its initial alignment, in order to establish a level orientation for the structure. Usually, such a linear level must be repositioned back and forth a number of times along the two axes being leveled, as the adjustment along one axis will throw off a previous adjustment along the other normal axis. While such fine adjustment may not be necessary for leveling a recreational vehicle for a relatively short period of time, it may be critical for a work table or the like, where extreme precision is required. In some instances, people have secured conventional level instruments to the structure in order to avoid the need to position and reposition a level or levels temporarily on the structure, each time it must be leveled. However, conventional levels have no adjustability built into them, as their bases are immovably fixed relative to the level indicator (bubble, etc.) display. This results in a great deal of difficulty in accurately positioning such a conventional level in a permanent attachment. While such levels can be shimmed and otherwise adjusted before being permanently secured in place, the very act of securing them (e.g., driving screws, applying adhesives, etc.) is often sufficient to induce some slight variance between true level and the level indicator. The user of the structure must thereafter always compensate for the error induced. The present invention provides a solution to the above problem, by means of a level instrument which is configured for permanent attachment to a movable or portable structure, and which provides for multiple axis adjustment to fine tune the device after installation. This assures that once the structure has been leveled, that the present level indicator can also be precisely leveled along or across multiple axes, with the present level device always providing a true indication of level (or deviation therefrom) for the structure to which it has been permanently secured. A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below. U.S. Pat. No. 4,829,676 issued on May 16, 1989 to David C. Waldron, titled “Hands-Free Level Indicating Device,” describes a conventional linear bubble or spirit level which has been modified with a slot at each end thereof, with a generally U-shaped clamp being placed in each slot. This configuration allows the level to be temporarily clamped to a wide number of different elongate objects (pipes, joists, etc.). Waldron does not provide any means of permanently attaching the level to a structure to be leveled, nor does the level include any means for adjusting its attitude after installation or attachment to another article or object. Moreover, the Waldron level cannot be used to provide an omnidirectional display of the level of a surface, as can the bull's eye level used with the present multiple axis installable and adjustable level. U.S. Pat. No. 5,163,229 issued on Nov. 17, 1992 to Giovanni F. Cantone, titled “Plumb And Horizontal Locating Device,” describes a pendulum type leveling instrument having a light beam therein to project a vertical or horizontal beam of light, depending upon the embodiment. Cantone does not disclose any means of permanently attaching his level to another object or structure, nor for adjusting the level of the base relative to the structure upon which it is place or attached. Moreover, the configuration of the Cantone level would require that the plumb bob be removed whenever the structure is moved. Precise replacement of the plumb bob would not be possible, due to minor variations in position while placing the plumb bob on its two mutually normal support rods. U.S. Pat. No. 5,174,034 issued on Dec. 29, 1992 to Richard L. Swanda, titled “All-Purpose Level,” describes a level which extends normal to a pair of hinge leaves. The device is adapted for use in determining the verticality of corners and the like, wherein the two leaves are extended along each side of the corner and the level is read to determine if the leaves, and therefore the sides which define the corner, are perpendicular. While the Swanda device uses hinge leaves, the leaves have no holes therethrough to permit the permanent attachment of the device to a structure; it must be held in place. Moreover, Swanda does not provide any form of adjustment for his level. In the event that it were to be attached to a non-vertical surface (or non-horizontal, in some embodiments), the level could not be adjusted to indicate level for the remainder of the structure. U.S. Pat. No. 5,402,579 issued on Apr. 4, 1995 to Robert K. Smith, titled “C-Clamps With Integral Bubble Levels,” describes a linear bubble type level permanently and immovably affixed to the back or spine of the C-clamp; no adjustment is possible. The Smith level and C-clamp combination can only be temporarily secured to a relatively thin and substantially vertical panel, to check the verticality of the panel. Smith provides no means for permanently securing a level to one side or surface of a panel, or for adjusting the level indicator after installation to match it to a true horizontal reference, which features are parts of the present invention. Moreover, the Smith device cannot utilize a bull's eye type level, as the leveling of the C-clamp about its clamping axis is arbitrary. U.S. Pat. No. 5,406,713 issued on Apr. 18, 1995 to Robert Oman et al., titled “Apparatus For Maintaining A Scientific And Measuring Instrument Or The Like In A Level Plane,” describes a tripod with a central column normal to the plane of the legs. A pendulum type device is disposed within the column, and determines the verticality of the column (and hence the horizontal attitude of the legs) by contact with contacts disposed upon the inner walls of the column when the column is not vertical. Contact results in the operation of one or more motors at the feet of the device in order to level the device automatically. The Oman device cannot be permanently installed upon a surface that is other than very close to horizontal, and no adjustment for the level means relative to the remainder of the tripod structure is provided. No visual level indication is provided. U.S. Pat. No. 5,421,094 issued on Jun. 6, 1995 to David W. McCord, titled “Adjustable Level,” describes an angle having a bull's eye type level secured to a plane normal to both arms of the angle. The device is primarily adapted for temporary placement along a pipe or column, to check the verticality of the pipe; no permanent attachment means is provided. While the plate upon which the bubble level is mounted can be turned to allow the device to check angles other than vertical, the bubble level adjustment is only in a single plane, and only for a relative few angles. McCord does not provide infinitesimal adjustment of his bubble level in two mutually perpendicular dimensions relative to the body of his device, whereas such infinitesimal, bidimensional adjustment is a part of the present invention. U.S. Pat. No. 5,628,521 issued on May 13, 1997 to Robert H. Schneider et al., titled “Manually Operated Vehicle Leveling System,” describes the installation of a series of hydraulic jacks in a recreational vehicle or the like. Schneider et al. recognize the desirability of leveling such vehicles when parked and used as living quarters, but only disclose the actual physical leveling system. The only means of measuring or checking the level of the vehicle mentioned by Schneider et al., is the use of a conventional, temporarily placed, portable bubble level (column 6, lines 10 and 11). Schneider et al. do not disclose any form of permanently mounted level indicator which is adjustable to match the level indicator with the true level of the structure after installation, as provided by the present invention. U.S. Pat. No. 5,839,200 issued on Nov. 24, 1998 to Dominic Decesare, titled “Multi-Function Horizontal And Vertical Alignment Tool,” describes a temporarily installable (no permanent mounting means are provided) bull's eye level, wherein the level is mounted upon an arcuately adjustable bracket secured to the elongate level body. The adjustment is only in a single plane, rather than being bi-directional, as in the case of the present level device. Moreover, Decesare provides only five different positions for his level adjustments relative to the level body. In contrast, the present level device is infinitesimally adjustable in any direction(s) defining a leveling plane, and in addition includes coarser initial adjustments which may be performed during the installation to permit the device to be permanently secured to virtually any surface, regardless of its angle or slope. U.S. Pat. No. 6,131,298 issued on Oct. 17, 2000 to William McKinney et al., titled “Self-Supporting Level Measurement Device,” describes an otherwise conventional multi-tube bubble level having a spring clamp removably secured to each end thereof. The clamps are used to temporarily secure the level to another structure, e.g., a framing stud, etc., to check the verticality thereof during construction. The clamps secure to the level body by means of square retaining studs in the manner used to secure a socket to the drive of a ratchet wrench. No means for permanently mounting the device to a surface, or for precisely adjusting the level vials relative to the body of the device after such installation, are disclosed by McKinney et al. U.S. Pat. No. 6,332,277 issued on Dec. 25, 2001 to Greg J. Owoc et al., titled “Level With Securing Apparatus,” describes an otherwise conventional level with a number of embodiments of devices for securing the level temporarily to another structure (framing stud, pipe, etc.). The various temporary securing means comprise clamps, straps, surrounding bands, etc. None of the securing means provides for the permanent attachment of the device to a generally planar surface, as does the present level indicator invention. Owoc et al. do not provide any means of adjusting the angles of the level vials within the conventional level body of their device. The Owoc et al. level is felt to resemble the level of the '298 U.S. patent to McKinney et al. more closely than it does the present invention. U.S. patent Publication Ser. No. 2001/25,426 published on Oct. 4, 2001, titled “Leveling Instrument-Clamping Device,” describes a specialized attachment mechanism for temporarily securing a surveyor's precision level to the top of a tripod. As such, the mechanism cannot be permanently secured to a generally planar surface, as provided by the present invention. Moreover, the level device disclosed in the '426 publication is not a component of the mechanism for which a patent is sought. Rather, the level adjustment mechanism merely provides an interface between an existing, conventional surveyor's level or the like, and the conventional tripod to which such levels are conventionally mounted for temporary use in the field. U.S. patent Publication Ser. No. 2002/174,553 published on Nov. 28, 2002, titled “Adjustable Level,” describes a three way tubular bubble level permanently and immovably attached to a pipe clamp type mechanism. The level body cannot be adjusted relative to the clamp mechanism, and no means is provided for permanently attaching the device to a generally planar structure, as provided by the present level. U.S. patent Publication Ser. No. 2003/93,909 published on May 22, 2003, titled “Level Having A Detachable And Quick Release Structure,” describes an insert for removable installation in a conventional level frame, for holding a small line level in the level frame. No means for permanently mounting the level to another surface, or for adjusting the level relative to the level frame, are provided. Finally, Japanese Patent Publication No. 7-292,865 published on Nov. 7, 1995, titled “Base Piece With Circular Level,” describes (according to the drawings and English abstract) a bracket for permanently imbedding within a concrete slab or the like. The bracket includes a U-shaped upper portion, to which a bull's eye level may be secured. No means for mechanically fastening the device to a generally planar panel, or for bidirectionally adjusting the level of the bubble level, is apparent. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a multi-axis installable and adjustable level solving the aforementioned problems is desired. SUMMARY OF THE INVENTION The present multi-axis installable and adjustable level provides an easily installed and inexpensive device for precisely leveling a structure periodically. Recreational vehicles and other mobile vehicles generally include some means of adjusting the chassis to provide a level orientation to compensate for any slope of the underlying terrain for the comfort of persons living therein. The present level device is particularly well-suited for permanent installation in such vehicles used as temporary living quarters from time to time. It is also useful for leveling work tables and the like when installed thereon. The present level includes a pair of leaves or shells which are pivotally secured together by hinges along a common edge. One of the leaves includes a series of fastener holes, enabling the device to be permanently secured to any suitable, generally planar surface. Coarse adjustment is provided by means of slots for the fastener holes. The other leaf includes a circular, bull's eye type level therein. Coarse adjustment between the two leaves is provided by a series of mating, radially disposed teeth formed in the mating faces of the hinge lugs. Once the hinge bolt is tightened, the leaves are locked together due to the engagement of the mating teeth. The structure is initially leveled using conventional measurement procedures. The present level device is then permanently installed upon any suitable surface, with the coarse adjustments noted above being made to provide an approximate indication of level for the bull's eye level. The bull's eye level includes fine adjustment means securing it to its underlying leaf, with the fine adjustment means providing infinitesimal adjustment of the bull's eye level relative to its leaf. This enables the bull's eye level to be adjusted precisely to match the previously leveled structure. Once the present level has been adjusted, no further adjustment, maintenance, or other work is required to use the device. Whenever the structure must be leveled, the user need only consult the previously installed and adjusted level of the present invention and adjust the level of the structure accordingly in order to precisely level the structure. Other embodiments provide for the folding of the two leaves, and means for precisely opening and aligning the folded leaf to its proper position. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an environmental, perspective view of the present multi-axis installable and adjustable level, showing its installation in a recreational vehicle. FIG. 2 is an exploded perspective view of the present level device, showing its various components. FIG. 3 is a perspective view of the present level, showing its configuration for installing upon a generally level surface. FIG. 4 is a perspective view of the present level in a configuration for installing upon an undercut sloped surface. FIG. 5 is a perspective view of the present level in a configuration for installing upon a surface sloped oppositely to that shown in FIG. 4. FIG. 6 is an exploded perspective view of an alternate embodiment of the present adjustable level, disclosing an adjustable mechanical stop for consistently opening the level. FIG. 7 is a side elevation view of the adjustable level embodiment of FIG. 6, showing its operation. FIG. 8 is an exploded perspective view of an alternate embodiment of the present adjustable level, disclosing adjustable alignment marks for consistently opening the level. FIG. 9 is a side elevation view of the adjustable level embodiment of FIG. 8, showing its operation. Similar reference characters denote corresponding features consistently throughout the attached drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention comprises various embodiments of a multi-axis installable and adjustable level for permanent installation in or on a portable or movable structure (e.g., a recreational vehicle, camper, work table, etc.) which must be moved from time to time and which must be positioned as nearly level as possible at each site where it is located. The present multi-axis level embodiments greatly facilitate the leveling of such structures by assuring that the level remains with the structure at all times, thereby obviating the necessity for the user to locate a portable level and position and reposition the level in various orientations across or along a surface to be leveled while adjusting the level of the structure. FIG. 1 provides an environmental illustration of the present multi-axis level 10, showing its attachment to the interior structure S of a recreational vehicle RV. The installation illustrated in FIG. 1 will be understood to be exemplary, with the present multi-axis level 10 capable of being installed to virtually any surface of any structure which requires leveling from time to time. In the case of recreational vehicles and the like, it is important that the vehicle be leveled when it is parked and used as living quarters for some period of time, in order to provide a level floor, table(s), counter surface(s), etc. for the occupants. The present multi-axis level 10 may be attached to any convenient structure, regardless of its orientation, and adjusted to provide a level indication. FIG. 2 provides an exploded perspective view of the present multi-axis level 10, showing its various components. The level 10 is essentially formed of a permanent attachment leaf 12 and a level display leaf 14 adjustably attached to one another by a hinge formed of a series of interlocking coarse adjustment hinge lugs 16, which permit adjustment of the relative angle between the leaves 12 and 14. An omnidirectional level display 18 is installed atop the level display leaf 14, for viewing by a person using the present level 10. The level display 18 is preferably a “bull's eye” type level, i.e., a circular bubble level providing a simultaneous level indication in any horizontal direction, as opposed to a linear level which provides an indication of level only in the direction in which it is oriented. The permanent attachment leaf 12 includes a series of attachment holes therethrough, as shown in FIGS. 2 through 5. A single circular fastener hole 20 may be provided through the lower center of the attachment leaf 12, with this hole 20 setting the location of the level 10 during installation. Two additional slotted coarse adjustment holes 22 are provided near the corners opposite the single circular hole 20, with the slotted holes 22 being positioned along an arc C of a fastener circle having its center defined by the circular hole 20. This arrangement permits the device 10 to be positioned generally when the first fastener 24 (shown in FIG. 1) is driven through the circular hole 20, with coarse angular adjustment of the attachment leaf 12 provided by the arcuate holes 22 about their fasteners 26 (also shown in FIG. 1). The above described attachment hole pattern permits some limited, coarse adjustment of the attachment plate 12 during installation, to adjust for any slight initial error in the positioning of the fastener attachment holes in the structure S. It will be seen that this does nothing to adjust the level of the level display leaf 14 in a plane orthogonal to the plane of the permanent attachment plate 12, however. Accordingly, the present multi-axis level 10 provides additional means for at least coarsely adjusting the level of the display leaf 14. The mating faces 28 of the hinge lugs 16 which extend from the attachment edges of each of the leaves 12 and 14 each include a series of radially disposed position locking teeth 30 which engage the teeth of the opposite mating face 28 of each lug 16 when the lugs 16 are compressed together. Preferably, the leaves 12 and 14 are formed of a rigid, inflexible material, such as a hard, durable plastic or metal material. A gap 31 is provided between the two center lugs 16, with the faces 33 (one of which is shown in FIG. 2) of these two center lugs being smooth. When the locking hinge bolt 32 is loose, the lugs 16 of the attachment leaf 12 and level display leaf 14 may slide axially toward one another along the bolt 32, due to the central gap 31 between the two center lugs 16. This results in clearances being developed between the toothed faces 28 of the first and second lug pair and third and fourth lug pair, allowing the lugs 16 to be rotated relative to one another to adjust the relative alignment of the two leaves 12 and 14. When the bolt 32 is tightened, the toothed faces 28 are forced together and the gap 31 is opened, as shown in FIGS. 3 through 5, to lock the two leaves 12 and 14 together. The bolt 32 may be tightened by engaging a conventional compatibly threaded nut (not shown), either separate from the opposite hinge lug 16 or molded or imbedded therein. The above described coarse adjustment means, i.e., the arcuate fastener slots 22 and mutually engaging hinge lug teeth 30, permit the plane of the level display leaf 14 to be adjusted to a reasonably close position along axes perpendicular and parallel to the hinge line of the leaves 12 and 14. However, the arcuate adjustment of the attachment leaf 12 by means of the fastener slots 22, and the finite number of teeth 30 of the hinge lugs 16, permit only an approximate adjustment for the level of the level display leaf 14 with its level display device 18. Accordingly, the present multi-axis level device 10 provides an infinitesimally fine omnidirectional adjustment mechanism of the level display 18, relative to its level display leaf 14 to which it is attached. This mechanism is disposed between the level display leaf 14 and its level display 18, with the components shown in detail in FIG. 2. A seat 34 is formed in the level display leaf 14, with the seat 34 having a series (preferably three evenly spaced) of threaded level display adjustment screw receptacles or bosses 36 therein. An omnidirectional level display mounting plate 38 supports the bubble level display 18, with the level 18 being adhesively or otherwise secured to the mounting plate 38. Alternatively, the plate 38 may be formed as an integral, peripherally extending flange of the level 18. The mounting plate 38 has a periphery with a corresponding series of level adjustment screw holes 40 formed therethrough, with a corresponding series of omnidirectional level display adjustment screws 42 installed through the holes 40 of the level mounting plate 38 and the threaded holes 36 of the level display plate 14. The above arrangement would allow the level mounting plate 38 to drop downwardly to rest directly within the seat 34 of the level display leaf 14, regardless of the positions of the screws or fasteners .42. Accordingly, a compression spring 44 is positioned concentrically between the level display mounting plate 38 and the underlying seat 34, to hold the position of the level display 18 as desired. The compression spring 44 provides a constant force urging the level display mounting plate 38 away from the underlying seat 34, against the heads of the level adjusting screws or fasteners 42. Thus, any portion of the periphery of the mounting plate 38 may be incrementally adjusted upwardly or downwardly by adjusting one or more of the adjusting screws or fasteners 42 inwardly or outwardly, as desired. FIGS. 3 through 5 provide illustrations of exemplary installation orientations for the present multi-axis level 10. The present multi-axis installable and adjustable level 10 may be secured to a surface having virtually any angle from horizontal to vertical, inclusive. The exemplary installation of FIG. 1 shows the device 10 installed upon an essentially vertical structure S. This is accomplished by securing the permanent attachment leaf 12 to the vertical structure S, loosening the hinge bolt 32 (if not previously accomplished), adjusting the level display leaf 14 to a substantially horizontal orientation, i.e., on the order of 90° to the attachment leaf 12 (precision is not necessary at this point), and tightening the hinge bolt 32 to lock the mating teeth 30 of the mating hinge lug faces 28 together to prevent relative motion between the leaves. The present multi-axis adjustable level 10 may also be secured to a substantially horizontal surface, if so desired. FIG. 3 illustrates such a configuration for the device 10, in which the two leaves 12 and 14 are folded together as closely as possible. The attachment leaf 12 includes a pair of mutually opposed edges 46 extending from the periphery thereof, normal to the plane of the leaf 12. The level display leaf 14 includes a pair of corresponding peripheral edges 48, and may include an additional peripheral edge 50 forming a depending wall around all sides of the level display leaf 14, excepting its hinge edge or side. The opposed edges 46 of the attachment leaf 12 and the corresponding edges 48 of the level display leaf 14 are coplanar with one another, and are in contact with one another when the two leaves 12 and 14 are folded as closely together as possible. This places the level display leaf 14 parallel to the attachment leaf 12. Thus, if it is desired to attach the attachment leaf 12 to a generally horizontal surface, the user need only fold the level display leaf 14 against the attachment leaf 12 until their respective opposed edges 46 and 48 are in contact with one another, to assure that the level display leaf 14 is also positioned generally horizontally, parallel to the attachment leaf 12. The hinge bolt 32 may then be tightened to bring the mating hinge lugs 16 into tight contact with one another, locking the relative position of the two leaves 12 and 14 together by means of the locking teeth 30 of the mating faces 28 of the hinge lugs 16. FIG. 4 illustrates an installation configuration for the present multi-axis installable and adjustable level 10, in which it is desired to secure the attachment leaf 12 to a sloped surface in which the surface slopes upwardly and toward the level display 18 of the level display leaf 14. In this installation, the two leaves 12 and 14 are opened to provide access to the screw or fastener holes 20 and 22 of the attachment leaf 12, the attachment leaf 12 is secured in place as desired, the level display leaf 14 is adjusted to a position reasonably close to level, and the hinge bolt 32 is tightened to lock the two leaves 12 and 14 immovably together, as described further above. FIG. 5 illustrates yet another installation configuration for the present multi-axis level 10, in which the attachment structure is sloped upwardly and away from the level display device 18 of the level display leaf 14. In this example, the two leaves 12 and 14 are opened as required to provide clearance for driving the fasteners 24 and 26 (shown in FIG. 1) through their respective holes 20 and 22 in the attachment leaf 12. The level display leaf 14 is then folded to a substantially horizontal position (again, precision is not required at this point) and the hinge bolt 32 tightened to lock the two leaves 12 and 14 immovably relative to one another. The above described installations use only the coarse adjustment features of the present multi-axis level 10, i.e. the slotted fastener holes 22 of the attachment leaf 12 and the mutually engaging teeth 30 of the facing hinge lugs 16, to position the level display leaf 14 in an approximately level orientation relative to two mutually orthogonal axes. This is not sufficiently accurate for many applications. Accordingly, the infinitesimal and omnidirectional adjustment of the level display device 18 by means of the componentry 34 through 44 illustrated in FIG. 2, enables the level display 18 to be adjusted to an extremely precise degree relative to the structure to which the device 10 is attached. The actual installation and leveling process first requires that the portable or movable object to which the present leveling device 10 is to be secured, be accurately leveled. This may be accomplished conventionally, e.g. using a conventional linear spirit level or other level indicator resting upon a surface desired to be in a level orientation when the object or structure is at rest, e.g. floor, table top, counter area, etc. in a recreational vehicle. Alternatively, if a surface intended to be level is available, the present leveling device 10 may be temporarily placed in its folded configuration (as shown in FIG. 3) on the surface to be leveled, and the device 10 may be used to check the progress of the leveling operation. The vehicle (or other object) is then leveled conventionally, using jacks and/or other means to level the structure as accurately as possible, while referring back to the leveling device from time to time. Once the structure has been leveled to the satisfaction of the user, the level indicator 10 may be installed, generally as described above. A suitable place is located, preferably in an unobtrusive position where the level indicator 10 may remain deployed without interference with other objects or persons, and the device 10 is permanently secured to the structure as described further above. This results in the level device 10 providing an indication which is reasonably close to level. However, the finite number of locking teeth 30 between the hinge lugs 16, and the difficulty in making the miniscule arcuate adjustments of the slotted coarse adjustment holes 22 of the attachment leaf 12, will nearly always result in the level display leaf 14 being slightly off from precise level relative to the remainder of the structure to which the leveling device 10 is secured. Other factors may also result in some slight deviation from level for the level display 18, such as any slight flexure of the plastic components as the hinge bolt 32 is tightened. However, the above is of no consequence, as the infinitesimal and omnidirectional adjustment of the level orientation of the level display 18 serves to compensate for any slight misalignment from true level for the rest of the device 10. Once the device 10 has been permanently attached to the structure at some location as desired, the user of the device 10 need only adjust the level display adjustment screws or fasteners 42 through the level display mounting plate 38 to precisely and accurately level the level display 18 relative to the previously leveled structure or object to which the present adjustable level 10 has been attached. As the structure was previously leveled before the installation of the present device 10, and the level display is leveled, it will be seen that the present level device 10 will thereafter always indicate a true level whenever the structure to which it is attached is precisely level. FIGS. 6 through 9 provide illustrations of a pair of alternate embodiments of the present adjustable level, having means for precisely repositioning the level display leaf after it has been refolded. FIGS. 6 and 7 provide illustrations of a multi-axis installable and adjustable level 100 having a mechanical stop to limit the opening of the level display leaf as desired. The level 100 includes a permanent attachment leaf 102 having a level display leaf 104 hingedly secured thereto. Each leaf 102 and 104 includes a series of hinge lugs 106 extending therefrom. A spherical, “bull's eye” type level 108 is affixed to the level display leaf 104, using the same adjustable attachment means shown in FIG. 2 for securing the level 18 to the level display leaf 14 of the level embodiment 10 of FIGS. 1 through 5. The permanent attachment leaf 102 includes a single circular attachment hole 110 and a pair of arcuate attachment holes 112 for angular adjustment, functioning in the same manner as that described further above for the attachment holes 20 and 22 of the level 10 embodiment. The hinge lugs 106 engage in the same manner as that described further above for the level embodiment 10 of FIGS. 1 through 5, i.e. by means of their mutually facing radially disposed locking teeth 120. Some axial play is permitted along the hinge bolt 122 to allow the locking teeth 120 to disengage from one another for angular,adjustment of the level display leaf 104 relative to the permanent attachment leaf 102, just as in the first embodiment level 10 of FIGS. 1 through 5. The mating smooth faces 123 of the center lugs permit smooth rotation of the two components 102 and 104 relative to one another when the hinge assembly is loosened. Tightening the bolt 122 urges the locking teeth 120 of the hinge lugs 106 together, thereby engaging the teeth 120 of adjacent lugs 106 with one another to lock the relative angular positions of the two leaves 102 and 104. A sleeve 125 and bushing 127 may be installed within the hinge lugs 106 for smoother operation, if so desired. The adjustable level 100 of FIGS. 6 and 7 differs from the level embodiment 10 of FIGS. 1 through 5, in that it includes a mechanical stop to limit the angular deployment of the level display leaf 104 relative to the permanent attachment leaf 102. This permits the level display leaf 104 to be folded against the attachment leaf 102 for storage when leveling of the structure is not required, yet allows the level display leaf 104 to be accurately repositioned without need to perform the initial leveling operation again. The level display leaf 104 includes a stop block 150 extending therefrom, along one edge and adjacent the hinge assembly thereof. A rotationally adjustable mechanical stop ring 152 is installed concentrically with the hinge bolt 122 by means of a bushing 154, with the stop ring 152 having a stop block engaging tab 156 extending therefrom. A semicircular slot 158 is formed in the stop ring 152, with a stop ring lock screw 160 passing through the stop ring slot 158 and engaging a mating hole 162 in the outer face of one hinge lug 106 of the permanent attachment leaf 102. A lock screw bushing 164 may be provided to space the head of the lock screw 160 from the stop ring 152, for ease of manipulation. FIG. 7 provides a side elevation view of the operation of the adjustable level 100. The adjustable level 100 of FIGS. 6 and 7 is installed upon or in a structure in the manner described further above for the level 10 of FIGS. 1 through 5, i.e. leveling the structure, securing the device 100 in an approximately level orientation, and then fine tuning the adjustment of the level vial 108 relative to its level display leaf 104. At this point, the stop ring 152 is rotated to abut the stop tab 156 against the stop block 150, and the stop ring lock screw 160 is secured tightly to immovably affix the stop ring 152 relative to the outer hinge lug of the permanent attachment leaf 102. The hinge bolt 122 may then be loosened and the level display leaf 104 folded against the permanent attachment leaf 102 for compact storage. When leveling of the apparatus is again required, all that is necessary is to fold the level display leaf 104 upwardly and outwardly until the stop block 150 of the level display leaf 104 contacts the previously adjusted stop ring tab 156 of the stop ring 152, thereby preventing further angular extension of the level display leaf 104. As the level display leaf 104 was perfectly level at the time the stop ring 152 was previously adjusted, the level display leaf 104 will once again be set to indicate the level of the apparatus to which it is attached when the stop block 150 of the level display leaf 104 is in contact with the stop ring tab 156 secured to the permanent attachment leaf 102. The adjustable level assembly 200 of FIGS. 8 and 9 is quite similar to the level assembly 100 of FIGS. 6 and 7, but includes a different means of assuring the repeated alignment of the level display leaf to its proper position after folding. The adjustable level 200 of FIGS. 8 and 9 includes the various equivalent components and features of the level 100 of FIGS. 6 and 7, i.e. permanent attachment and level display leaves 202 and 204 with their mating hinge lugs 206, a spherical “bull's eye” level 208 adjustably affixed to the level display leaf 204, and mounting holes 210 and 212 in the attachment leaf 202. The lugs 206 include abutting radially toothed faces 220, which lock together when the hinge bolt 222 is tightened. Axial play in the hinge lugs 206 permit the toothed faces 220 to disengage, with the smooth hinge lug faces 223 allowing relative rotation of the two leaves 202 and 204. As an alternative construction, the hinge bolt passages through the hinge lugs are substantially the same diameter as the hinge bolt 222, allowing the elongate sleeve of the embodiment of FIGS. 6 and 7 to be omitted. A relatively large hinge bolt bushing 227 is provided in lieu of the sleeve. It will be understood that either hinge construction may be used with any of the embodiments of the present invention, as desired. The level display leaf 204 includes a stop or alignment block 250 extending therefrom, in a position equivalent to the stop block 150 of the embodiment 100 of FIGS. 6 and 7. The alignment block 250 further includes a fixed alignment mark 251 thereon, extending radially from the hinge axis of the assembly. An alignment ring 252 is adjustably installed concentrically with the hinge bolt 222 by means of a bushing 254, with the alignment ring 252 having an adjustable alignment mark 256 thereon. A semicircular slot 258 is formed in the alignment ring 252, with an alignment ring lock screw 260 passing through the alignment ring slot 258 and engaging a mating hole 262 in the outer face of one hinge lug 206 of the permanent attachment leaf 202. A lock screw bushing 264 may be provided to space the head of the lock screw 260 from the stop ring 252, for ease of manipulation. FIG. 9 provides a side elevation view of the operation of the adjustable level 200. The adjustable level 200 of FIGS. 8 and 9 is installed upon or in a structure in the manner described further above for the level 10 of FIGS. 1 through 5, i.e. leveling the structure, securing the device 200 in an approximately level orientation, and then fine tuning the adjustment of the level vial 208 relative to its level display leaf 204. At this point, the stop ring 252 is rotated to align its adjustable alignment mark 256 with the fixed alignment mark 251 of the alignment block 250 of the level display leaf 204, and the alignment ring lock screw 260 is secured tightly to immovably affix the alignment ring 252 relative to the outer hinge lug of the permanent attachment leaf 202. The hinge bolt 222 may then be loosened and the level display leaf 204 folded against the permanent attachment leaf 202 for compact storage. When leveling of the apparatus is again required, all that is necessary is to fold the level display leaf 204 upwardly and outwardly until the fixed alignment mark 251 of the alignment block 250 of the level display leaf 204 is aligned with the previously adjusted alignment mark 256 of the alignment ring 252. As the level display leaf 204 was perfectly level at the time the alignment ring 252 was previously adjusted, the level display leaf 204 will once again be set to indicate the level of the apparatus to which it is attached when the alignment mark 251 of the alignment block 250 of the level display leaf 204 is in precise alignment with the alignment ring mark 256 of the alignment ring 252 secured to the permanent attachment leaf 102. In conclusion, the present multi-axis installable and adjustable level in its various embodiments provides a much needed means of quickly and accurately establishing a level attitude for virtually any movable structure which must be leveled for use in its stationary state. The present leveling device is relatively inexpensive to manufacture, and may be readily purchased by virtually anyone who has need of such a device. The present leveling device may be used to verify the leveling of an object or structure where any suitable conventional physical leveling means is used to actually adjust the level of the structure. However, the present leveling device is particularly well suited for use with automated leveling devices, where the user may remotely adjust the level of the structure or vehicle by means of an electrohydraulic or other powered system, merely by observing the indication provided by the present leveling device and adjusting the controls accordingly. Regardless of the physical leveling means used, the present leveling device will save considerable time and prove considerably more convenient than earlier devices and leveling methods of the related art. It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates generally to indicating devices for displaying a level line or plane, and more specifically to a leveling device which is permanently installed and adjusted on or in a movable structure, whereupon the structure may be accurately leveled by means of the present leveling device. The present level includes a two way adjustable base and an infinitesimally adjustable “bull's eye” type bubble level vial, whereby the device may be finely adjusted after installation to provide a level reference whenever the structure to which it is secured is moved. 2. Description of the Related Art There are innumerable portable structures which require at least a close approximation of a level attitude when they are relocated periodically. Examples of such are motor homes, house trailers, and camper type vehicles. Oftentimes, a craftsman must erect a work table or the like, which requires a level attitude for accurate work. The conventional technique nearly universally used for leveling such structures is to place a level (e.g., linear or bull's eye level, electronic leveling device, etc.) temporarily on or across a surface of the structure desired to be leveled, adjust the structure until it is level according to the level instrument, and remove the instrument from the structure. The problem with this technique is that the portable level must be repositioned on or in the structure, each time it is necessary to level the structure. In those cases where a linear level is used, the level must be repositioned at least once, normal to its initial alignment, in order to establish a level orientation for the structure. Usually, such a linear level must be repositioned back and forth a number of times along the two axes being leveled, as the adjustment along one axis will throw off a previous adjustment along the other normal axis. While such fine adjustment may not be necessary for leveling a recreational vehicle for a relatively short period of time, it may be critical for a work table or the like, where extreme precision is required. In some instances, people have secured conventional level instruments to the structure in order to avoid the need to position and reposition a level or levels temporarily on the structure, each time it must be leveled. However, conventional levels have no adjustability built into them, as their bases are immovably fixed relative to the level indicator (bubble, etc.) display. This results in a great deal of difficulty in accurately positioning such a conventional level in a permanent attachment. While such levels can be shimmed and otherwise adjusted before being permanently secured in place, the very act of securing them (e.g., driving screws, applying adhesives, etc.) is often sufficient to induce some slight variance between true level and the level indicator. The user of the structure must thereafter always compensate for the error induced. The present invention provides a solution to the above problem, by means of a level instrument which is configured for permanent attachment to a movable or portable structure, and which provides for multiple axis adjustment to fine tune the device after installation. This assures that once the structure has been leveled, that the present level indicator can also be precisely leveled along or across multiple axes, with the present level device always providing a true indication of level (or deviation therefrom) for the structure to which it has been permanently secured. A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below. U.S. Pat. No. 4,829,676 issued on May 16, 1989 to David C. Waldron, titled “Hands-Free Level Indicating Device,” describes a conventional linear bubble or spirit level which has been modified with a slot at each end thereof, with a generally U-shaped clamp being placed in each slot. This configuration allows the level to be temporarily clamped to a wide number of different elongate objects (pipes, joists, etc.). Waldron does not provide any means of permanently attaching the level to a structure to be leveled, nor does the level include any means for adjusting its attitude after installation or attachment to another article or object. Moreover, the Waldron level cannot be used to provide an omnidirectional display of the level of a surface, as can the bull's eye level used with the present multiple axis installable and adjustable level. U.S. Pat. No. 5,163,229 issued on Nov. 17, 1992 to Giovanni F. Cantone, titled “Plumb And Horizontal Locating Device,” describes a pendulum type leveling instrument having a light beam therein to project a vertical or horizontal beam of light, depending upon the embodiment. Cantone does not disclose any means of permanently attaching his level to another object or structure, nor for adjusting the level of the base relative to the structure upon which it is place or attached. Moreover, the configuration of the Cantone level would require that the plumb bob be removed whenever the structure is moved. Precise replacement of the plumb bob would not be possible, due to minor variations in position while placing the plumb bob on its two mutually normal support rods. U.S. Pat. No. 5,174,034 issued on Dec. 29, 1992 to Richard L. Swanda, titled “All-Purpose Level,” describes a level which extends normal to a pair of hinge leaves. The device is adapted for use in determining the verticality of corners and the like, wherein the two leaves are extended along each side of the corner and the level is read to determine if the leaves, and therefore the sides which define the corner, are perpendicular. While the Swanda device uses hinge leaves, the leaves have no holes therethrough to permit the permanent attachment of the device to a structure; it must be held in place. Moreover, Swanda does not provide any form of adjustment for his level. In the event that it were to be attached to a non-vertical surface (or non-horizontal, in some embodiments), the level could not be adjusted to indicate level for the remainder of the structure. U.S. Pat. No. 5,402,579 issued on Apr. 4, 1995 to Robert K. Smith, titled “C-Clamps With Integral Bubble Levels,” describes a linear bubble type level permanently and immovably affixed to the back or spine of the C-clamp; no adjustment is possible. The Smith level and C-clamp combination can only be temporarily secured to a relatively thin and substantially vertical panel, to check the verticality of the panel. Smith provides no means for permanently securing a level to one side or surface of a panel, or for adjusting the level indicator after installation to match it to a true horizontal reference, which features are parts of the present invention. Moreover, the Smith device cannot utilize a bull's eye type level, as the leveling of the C-clamp about its clamping axis is arbitrary. U.S. Pat. No. 5,406,713 issued on Apr. 18, 1995 to Robert Oman et al., titled “Apparatus For Maintaining A Scientific And Measuring Instrument Or The Like In A Level Plane,” describes a tripod with a central column normal to the plane of the legs. A pendulum type device is disposed within the column, and determines the verticality of the column (and hence the horizontal attitude of the legs) by contact with contacts disposed upon the inner walls of the column when the column is not vertical. Contact results in the operation of one or more motors at the feet of the device in order to level the device automatically. The Oman device cannot be permanently installed upon a surface that is other than very close to horizontal, and no adjustment for the level means relative to the remainder of the tripod structure is provided. No visual level indication is provided. U.S. Pat. No. 5,421,094 issued on Jun. 6, 1995 to David W. McCord, titled “Adjustable Level,” describes an angle having a bull's eye type level secured to a plane normal to both arms of the angle. The device is primarily adapted for temporary placement along a pipe or column, to check the verticality of the pipe; no permanent attachment means is provided. While the plate upon which the bubble level is mounted can be turned to allow the device to check angles other than vertical, the bubble level adjustment is only in a single plane, and only for a relative few angles. McCord does not provide infinitesimal adjustment of his bubble level in two mutually perpendicular dimensions relative to the body of his device, whereas such infinitesimal, bidimensional adjustment is a part of the present invention. U.S. Pat. No. 5,628,521 issued on May 13, 1997 to Robert H. Schneider et al., titled “Manually Operated Vehicle Leveling System,” describes the installation of a series of hydraulic jacks in a recreational vehicle or the like. Schneider et al. recognize the desirability of leveling such vehicles when parked and used as living quarters, but only disclose the actual physical leveling system. The only means of measuring or checking the level of the vehicle mentioned by Schneider et al., is the use of a conventional, temporarily placed, portable bubble level (column 6, lines 10 and 11). Schneider et al. do not disclose any form of permanently mounted level indicator which is adjustable to match the level indicator with the true level of the structure after installation, as provided by the present invention. U.S. Pat. No. 5,839,200 issued on Nov. 24, 1998 to Dominic Decesare, titled “Multi-Function Horizontal And Vertical Alignment Tool,” describes a temporarily installable (no permanent mounting means are provided) bull's eye level, wherein the level is mounted upon an arcuately adjustable bracket secured to the elongate level body. The adjustment is only in a single plane, rather than being bi-directional, as in the case of the present level device. Moreover, Decesare provides only five different positions for his level adjustments relative to the level body. In contrast, the present level device is infinitesimally adjustable in any direction(s) defining a leveling plane, and in addition includes coarser initial adjustments which may be performed during the installation to permit the device to be permanently secured to virtually any surface, regardless of its angle or slope. U.S. Pat. No. 6,131,298 issued on Oct. 17, 2000 to William McKinney et al., titled “Self-Supporting Level Measurement Device,” describes an otherwise conventional multi-tube bubble level having a spring clamp removably secured to each end thereof. The clamps are used to temporarily secure the level to another structure, e.g., a framing stud, etc., to check the verticality thereof during construction. The clamps secure to the level body by means of square retaining studs in the manner used to secure a socket to the drive of a ratchet wrench. No means for permanently mounting the device to a surface, or for precisely adjusting the level vials relative to the body of the device after such installation, are disclosed by McKinney et al. U.S. Pat. No. 6,332,277 issued on Dec. 25, 2001 to Greg J. Owoc et al., titled “Level With Securing Apparatus,” describes an otherwise conventional level with a number of embodiments of devices for securing the level temporarily to another structure (framing stud, pipe, etc.). The various temporary securing means comprise clamps, straps, surrounding bands, etc. None of the securing means provides for the permanent attachment of the device to a generally planar surface, as does the present level indicator invention. Owoc et al. do not provide any means of adjusting the angles of the level vials within the conventional level body of their device. The Owoc et al. level is felt to resemble the level of the '298 U.S. patent to McKinney et al. more closely than it does the present invention. U.S. patent Publication Ser. No. 2001/25,426 published on Oct. 4, 2001, titled “Leveling Instrument-Clamping Device,” describes a specialized attachment mechanism for temporarily securing a surveyor's precision level to the top of a tripod. As such, the mechanism cannot be permanently secured to a generally planar surface, as provided by the present invention. Moreover, the level device disclosed in the '426 publication is not a component of the mechanism for which a patent is sought. Rather, the level adjustment mechanism merely provides an interface between an existing, conventional surveyor's level or the like, and the conventional tripod to which such levels are conventionally mounted for temporary use in the field. U.S. patent Publication Ser. No. 2002/174,553 published on Nov. 28, 2002, titled “Adjustable Level,” describes a three way tubular bubble level permanently and immovably attached to a pipe clamp type mechanism. The level body cannot be adjusted relative to the clamp mechanism, and no means is provided for permanently attaching the device to a generally planar structure, as provided by the present level. U.S. patent Publication Ser. No. 2003/93,909 published on May 22, 2003, titled “Level Having A Detachable And Quick Release Structure,” describes an insert for removable installation in a conventional level frame, for holding a small line level in the level frame. No means for permanently mounting the level to another surface, or for adjusting the level relative to the level frame, are provided. Finally, Japanese Patent Publication No. 7-292,865 published on Nov. 7, 1995, titled “Base Piece With Circular Level,” describes (according to the drawings and English abstract) a bracket for permanently imbedding within a concrete slab or the like. The bracket includes a U-shaped upper portion, to which a bull's eye level may be secured. No means for mechanically fastening the device to a generally planar panel, or for bidirectionally adjusting the level of the bubble level, is apparent. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a multi-axis installable and adjustable level solving the aforementioned problems is desired. | <SOH> SUMMARY OF THE INVENTION <EOH>The present multi-axis installable and adjustable level provides an easily installed and inexpensive device for precisely leveling a structure periodically. Recreational vehicles and other mobile vehicles generally include some means of adjusting the chassis to provide a level orientation to compensate for any slope of the underlying terrain for the comfort of persons living therein. The present level device is particularly well-suited for permanent installation in such vehicles used as temporary living quarters from time to time. It is also useful for leveling work tables and the like when installed thereon. The present level includes a pair of leaves or shells which are pivotally secured together by hinges along a common edge. One of the leaves includes a series of fastener holes, enabling the device to be permanently secured to any suitable, generally planar surface. Coarse adjustment is provided by means of slots for the fastener holes. The other leaf includes a circular, bull's eye type level therein. Coarse adjustment between the two leaves is provided by a series of mating, radially disposed teeth formed in the mating faces of the hinge lugs. Once the hinge bolt is tightened, the leaves are locked together due to the engagement of the mating teeth. The structure is initially leveled using conventional measurement procedures. The present level device is then permanently installed upon any suitable surface, with the coarse adjustments noted above being made to provide an approximate indication of level for the bull's eye level. The bull's eye level includes fine adjustment means securing it to its underlying leaf, with the fine adjustment means providing infinitesimal adjustment of the bull's eye level relative to its leaf. This enables the bull's eye level to be adjusted precisely to match the previously leveled structure. Once the present level has been adjusted, no further adjustment, maintenance, or other work is required to use the device. Whenever the structure must be leveled, the user need only consult the previously installed and adjusted level of the present invention and adjust the level of the structure accordingly in order to precisely level the structure. Other embodiments provide for the folding of the two leaves, and means for precisely opening and aligning the folded leaf to its proper position. | 20040324 | 20060103 | 20050929 | 89010.0 | 0 | GUADALUPE, YARITZA | MULTI-AXIS INSTALLABLE AND ADJUSTABLE LEVEL | SMALL | 0 | ACCEPTED | 2,004 |
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10,807,465 | ACCEPTED | Release planning | A method of software release planning. The method comprises the steps of assigning stakeholder priorities to a set of requirements for software; explicitly defining a set of constraints on the requirements; and operating on the stakeholder priorities with algorithms using a computer, subject to the constraints, to generate at least one release plan solution. Priorities are balanced between priorities of multiple stakeholders, and between the impact of various release plan solutions on project time, overall benefit, and quality of the software. A set of near optimal and maximally distinct solutions is generated. | 1. A method of release planning, the method comprising the steps of: assigning stakeholder priorities to a set of requirements, where the priorities are assigned by plural stakeholders; explicitly defining a set of constraints on the requirements; using algorithms carried out by a computer, exploring release plan solutions that satisfy the constraints and balance between stakeholder priorities of different stakeholders to generate a set of candidate release plan solutions that have a positive impact on at least one of project time, overall cost and quality; and selecting at least one release plan solution from the set of candidate release plan solutions. 2. The method of claim 1 in which operating on the stakeholder priorities with algorithms using a computer is carried out repeatedly after changing one or more of the constraints, requirements or stakeholder priorities. 3. The method of claim 1 in which a set of release plan solutions is generated and the solution set is further qualified by applying a concordance/non-discordance principle. 4. The method of claim 3 in which the algorithms comprise one or more of genetic algorithms, heuristic algorithms and integer programming algorithms. 5. The method of claim 4 in which the algorithms use at least one objective function to evaluate release plan solutions. 6. The method of claim 5 in which the objective function comprises an aggregation of stakeholder priorities or value estimates. 7. The method of claim 6 in which computation of the algorithms is carried out externally from an application service provider, and stakeholder priorities are input to the computer from remote locations. 8. The method of claim 2 in which changing the requirements comprises actions chosen from a group consisting of: adding additional requirements; removing existing requirements; modifying existing requirements; and adjusting stakeholder priorities. 9. The method of claim 2 further comprising the step of assigning the requirements to one of the next release, the next but one release, or unassigned. 10. The method of claim 9 in which repeating the step of operating on the stakeholder priorities or value estimates with the algorithms comprises using the unassigned requirements as the requirements in the repeated step. 11. The method of claim 1 in which selecting a release plan solution from the set of candidate release plan solutions is carried out by a problem solver. 12. The method of claim 1 in which the method is carried out through a hybrid approach integrating computational intelligence and human intelligence. 13. The method of claim 1 in which the set of constraints is chosen from a group consisting of precedence relationships between requirements, coupling relationships between requirements, effort, resource, budget, risk, and time. 14. The method of claim 1 in which stakeholder priorities are represented by a numerical value representing stakeholder satisfaction that a requirement be assigned to one of three categories, the categories consisting of the next release, the next but one release, and postponed. 15. The method of claim 1 in which the requirements are grouped into groups of requirements and the algorithms balance between stakeholder priorities assigned to the groups of requirements. 16. The method of claim 1 in which stakeholders prioritize subsets of the complete set of requirements. 17. The method of claim 1 further comprising providing on demand an answer to questions chosen from a group of questions consisting of: why requirements are assigned to a certain release; why requirements are not assigned to a certain release; which are commonalities in the proposed solutions; and which are differences in the proposed solutions. 18. The method of claim 1 where a set of near optimal and maximally distinct alternative release plan solutions is generated. 19. The method of claim 1 where different use cases are predefined 20. The method of claim 21 where process guidance is provided to perform the scenario use cases. 21. A computer programmed to carry out the method steps of claim 1. 22. Computer readable media containing instructions for a computer to carry out the method steps of claim 1. | BACKGROUND OF THE INVENTION Requirements management in general is concerned with the control of system requirements that are allocated to software to resolve issues before they are incorporated into the software project. It aims to accurately adjust plans and cost estimates as the requirements change, and to prioritize requirements according to their importance and their contribution to the final value of the product. There is very good reason to significantly improve the maturity of these processes. According to the Standish Research Group (“What are your requirements?” http://www.standishgroup.com/, 2002), the three leading causes of quality and delivery problems in software projects are related to requirements management issues: Lack of adequate user input, incomplete requirements and specifications, and changing requirements specifications. A software release is a collection of new and/or changed features or requirements that form a new product. Release planning for incremental software development assigns features to releases such that most important technical, resource, risk and budget constraints are met. Without good release planning ‘critical’ features are jammed into the release late in the cycle without removing features or adjusting dates. This might result in unsatisfied customers, time and budget overruns, and a loss in market share, as indicated by Penny D., “An Estimation-Based Management Framework for Enhancive Maintenance in Commercial Software Products”, in Proc. International Conference on Software Maintenance, 2002. “Developing and releasing small increments of requirements, in order for customers to give feedback early, is a good way of finding out exactly what customers want, while assigning a low development effort” as stated in Carlshamre, P., “Release Planning in Market-Driven Software Product Development: Provoking an Understanding”. In: Requirements Engineering 7, pp 139-151, 2002. There is a growing recognition that features act as an important organizing concept within the problem domain and as a communication mechanism between users and developers. They provide an efficient way to manage the complexity and size of requirements. The concept of a feature is applicable and important for any software development paradigm. However, it is especially important for any type of incremental product development. Features are the “selling units” provided to the customer. Incremental development has many advantages over the traditional waterfall approach. First, prioritization of features ensures that the most important features are delivered first. This implies that benefits of the new system are realized earlier. Consequently, less important features are left until later and so, if the time or budget is not sufficient, the least important features are the ones most likely to be omitted. Second, customers receive an early version of the system and so are more likely to support the system and to provide feedback on it. Third, the schedule and cost for each delivery stage are easier to estimate due to smaller system size. This facilitates project management and control. Fourth, user feedback can be obtained at each stage and plans can be adjusted accordingly. Fifth, an incremental approach is sensitive to changes or additions to features. Agile methods as described in Cockburn, A., “Agile Software Development”, Pearson Education, 2002, have capitalized on the above advantages. In Extreme Programming (Beck, K. “Extreme Programming Explained”, Addison Wesley, 2001), a software product is first described in terms of ‘user stories’. These are informal descriptions of user requirements. In the planning process, these stories are prioritized using the perceived value to the user and assigned to releases. Based on estimates of how long each story in an increment will take to implement, an iteration plan is developed for delivering that release. Each increment (or release) is a completed product of use to the customer. At any time, new stories may be added and incorporated into future releases. The requirements engineering process is a decision-rich problem solving activity (Aurum, A., Wohlin, C., “The Fundamental Nature of Requirement Engineering Activities as a Decision-Making Process”, Information and Software Technology 2003, Vol. 45 (2003), No. 14, pp. 945-954.) One of the most prominent issues involved in incremental software development is to decide upon the most promising software release plans while taking into account diverse qualitative and quantitative project data. This is called release planning. The input for the release planning process is a set of features that are evolving due to changing user requirements and better problem understanding. Despite the obvious importance of the problem in current incremental and evolutionary development, it is poorly studied in the literature. Release planning considers stakeholder priorities and different types of constraints. The output of the release planning process is a set of candidate assignments of features to increments. They are supposed to represent a good balance between stakeholder priorities and the shortage of resources. In each increment, all the features are executed following one of the existing software development paradigms including analysis, system design, detailed design, implementation, component testing, system testing, and user testing. All the features are inputted into this process. As a result, a usable (release) product is provided. This fundamental procedure of planning and development of releases is illustrated in FIG. 2. Release planning assigns features to release options 1 (dark grey), 2 (grey) or 3 (white). Within each release development cycles, all features are passing the stages of a software development cycle. This cycle includes verification and validation activities at the different product stages (requirement, system design, component design, code). At the end of this process, a verified and validated release product is delivered. This principle can be easily extended to planning of more than two releases ahead. Without any technological, resource, risk and financial constraints, all the features could be implemented in one release. However, the existence of all the constraints implies the questions: what comes first and why? The goal of release planning is to account for all these factors and to come up with suggestions for the most satisfactory release plans. There are two fundamental types of release planning problems: (i) release planning with fixed and pre-determined time interval for implementation, and (ii) planning with flexible intervals. In the second problem, you also decide about the length of the interval to implement all the assigned features. This type of planning is also called ‘Open scope release planning’. Software Release Planning adds to two well-established disciplines of (incremental) software development: (i) requirements management, especially requirements prioritization, and (ii) software project planning and management. Defining the commonalities and differences between them helps to better understand release planning. Requirements management is the process of identifying, documenting, communicating, tracking and managing project requirements as well as changes to those requirements. As requirements are changing, or are becoming better understood, or new requirements are arising, requirements management is an ongoing activity. Requirements prioritization is trying to determine the different degrees of priority. The problem of still delivering a large amount of features that are never used, and vice versa, not delivering those that are required, has (among others) to do with a lack of understanding and prioritization. As a feature has different relevant attributes (such as its functionality, inherent risk, effort of implementation) that contribute to the final judgement, requirements prioritization is a multi-attributive decision problem. Practically, most emphasis is on the provided functionality of the feature. Specifically, requirements prioritization is also a multi-person (multi-criteria) decision problem, as the prioritization is typically performed in a team-session. There is no clear description on how the different and conflicting opinions are actually negotiated. Release planning may be characterized as “wicked”. That means that the objective is “to maximize the benefit”, but it is difficult to give a measurable definition of “benefit”. Wicked problems have no stopping rule in its solution procedure. The underlying model is “evolving”: the more we study the problem, the more sophisticated the model becomes. Wicked problems have better or worse solutions, but no optimal one. Although we are approximating the reality, implicit and tacit judgment and knowledge will always influence the actual decisions. As a consequence of all these difficulties, we propose to rely on the synergy between computational strength and the experience and intelligence of the human decision maker as proposed by the paradigm of software engineering decision support. Release planning is a very complex problem including different stakeholder perspectives, competing objectives and different types of constraints. Release planning is impacted by a huge number of inherent constraints. Most of the features are not independent from each other. Typically, there are precedence and/or coupling constraints between them that have to be satisfied. Furthermore, effort, resource, and budget constraints have to be fulfilled for each release. The overall goal is to find a relatively small set of “most promising” release plans such that the overall value and the degree of satisfaction of all the different stakeholders are maximized. The topic of investigation is uncertain and incomplete in its nature: Features are not well specified and understood: There is usually no formal way to describe the features and requirements. Non-standard format of feature specification often leads to incomplete descriptions and makes it harder for stakeholders to properly understand and evaluate features and requirements. Stakeholder involvement: In most cases, stakeholders are not sufficiently involved in the planning process. This is especially true for the final users of the system. Often, stakeholders are unsure why certain plans were suggested. In the case of conflicting priorities, knowing the details of compromises and why they were made would be useful. All these issues add to the complexity of the problem at hand and if not handled properly, they create a huge possibility for project failures Change of features and requirements and other problem parameters: Features and requirements always change as the project progresses. If a large number of features increase the complexity of the project, their dynamic nature can pose another challenge. Other parameters such as the number of stakeholders, their priorities, etc., also change with time—adding to the overall complexity. Size and complexity of the problem: Size and complexity are major problems for project managers when choosing release plans—some projects may have hundreds or even thousands of features. The size and complexity of the problem (known to be NP-complete), and the tendency for not involving all of the contributing factors, makes the problem prohibitively difficult to solve by individual judgment or trial and error type methods. Uncertainty of data: Meaningful data for release planning are hard to gather and/or uncertain. Specifically, estimates of the available effort, dependencies of features, and definition of preferences from the perspective of involved stakeholders are difficult to gauge. Availability of data: Different types of information are necessary for actually conducting release planning. Some of the required data are available from other information sources within the organization. Ideally, release planning is incorporated into existing Enterprise Resource Planning or other organizational information systems. Constraints: A project manager has to consider various constraints while allocating the features and requirements to various releases. Most frequently, these constraints are related to resources, schedule, budget or effort. Unclear objectives: ‘Good’ release plans are hard to define at the beginning. There are competing objectives such as cost and benefit, time and quality, and it is unclear which target level should be achieved. Efficiency and effectiveness of release planning: Release plans have to be updated frequently due to changing project and organizational parameters. Ad hoc methods help determine solutions but are far behind objective demands. Tool support: Currently, only general-purpose tools for features management are available. Most of them do not focus on the characteristics of release planning. Solution Methods and Techniques Prioritization in general answers the questions to classify objects according to their importance. This does not necessarily imply a complete ranking of all objects, but at least an assignment to classes like ‘Extremely important’, ‘important’, or ‘of moderate importance’. Different scales are applicable according to the underlying degree of knowledge you have about the objects. Prioritization always assumes one or a collection of criteria to actually perform the process. In Karlsson, J., Wohlin, C and Regnell, B., “An Evaluation of Methods for Prioritising Software Requirements”, Information and Software Technology 39 (1998), pp 939-947, a requirements prioritization session is characterized by three consecutive stages: Preparation: Structuring of the requirements according to the principles of the method to be applied. Provide all information available. Execution: Agreement on criteria between all team members. Decision makers do the actual prioritization with all the information available. In general, this step needs negotiation and re-iteration. Presentation: Final presentation of results to those involved in the process. There are a number of existing approaches to requirements prioritization. The most important ones have been studied and compared in Karlsson et al. (referenced above). Among them are the analytic hierarchy process (AHP), binary search tree creation, greedy-type algorithms and other sorting-based methods. As a result of their evaluation, they have found out that AHP is the most promising approach. Most of those algorithms need O(n2) comparisons between the n requirements. This effort required soon becomes prohibitive for larger number of requirements. In addition to that, none of the mentioned algorithms takes into account different stakeholder perspectives. The Analytic Hierarchy Process (AHP) is a systematic approach to elicit implicit preferences between different involved attributes, as discussed in Saaty T. L.: The Analytic Hierarchy Process, Wiley, New York, 1980. For the purpose of this investigation, AHP is applied to determine the importance of the various stakeholders from a business perspective. In addition, it is used to prioritize the different classes of requirements from the perspective of each stakeholder. The two preference schemata are combined to judge rank the importance of the different classes of requirements for the final business value of the software product. AHP assumes that the problem under investigation can be structured as an attributive hierarchy with at least three levels. On At the first level, the overall goal is described. The second level is to describes the different competing criteria that refining the overall goal of level 1. Finally, the third level is devoted to be used for the selection from competing alternatives. At each level of the hierarchy, a decision-maker performs a pair-wise comparison of attributes assessing their contributions to each of the higher level nodes to which they are linked. This pair-wise comparison involves preference ratios (for actions) or importance ratios (for criteria). The expert assigns an importance number that represents the importance of a term ti with respect to another term tj to describe the domain. Priority decisions become more complicated in the presence of stakeholders having different relative importance and different preferences. It becomes very hard in the presence of constraints about sequencing and coupling of requirements in various increments, and taking into account resource allocation for implementation of requirements. None of the methods mentioned above can be applied under these circumstances. Amongst the informal approaches claiming to handle release-planning, one of the most well known ones is ‘planning games’ as used in agile development. The goal of this approach is to deliver maximum value to the customer in least time possible. In half to one day long sessions, customers write story cards describing the features they want, while developers assign their estimates to those features. The customers then choose the most promising story cards for the next increment by either setting a release date and adding the cards until the estimated total matches the release date, or selecting the highest value cards first and setting the release date based on the estimates given on them. This simplistic approach works well in smaller projects. However, as the size and the complexity of the projects increases, the decisions involved in release planning become very complex. Various factors come into play, such as the presence of stakeholders having different relative importance and different preferences, the presence of constraints about sequencing and coupling of requirements in various increments, and the need to take into account resource allocation issues for implementing the requirements. Considering problems involving several hundreds of requirements and large number of widely scattered stakeholders, it becomes very hard to find appropriate solutions without intelligent support tools. The goal of such support is to account for all these factors in order to come up with a set of most promising release plans. SUMMARY OF THE INVENTION There is therefore provided, according to an aspect of the invention, a method of release planning. The method comprises the steps of assigning stakeholder priorities to a set of requirements, where the priorities are assigned by plural stakeholders; explicitly defining a set of constraints on the requirements; and using algorithms carried out by a computer, exploring release plan solutions that satisfy the constraints and balance between stakeholder priorities of different stakeholders to generate a set of candidate release plan solutions that have a positive impact on at least one of project time, overall cost and quality; and selecting at least one release plan solution from the set of candidate release plan solutions. The solution may be further qualified by applying a concordance/non-discordance principle. A set of near optimal and maximally distinct solutions may also be generated. Operating on the stakeholder priorities with algorithms using a computer may be carried out repeatedly after changing one or more of the constraints, requirements or stakeholder priorities, which may comprise actions chosen from a group consisting of adding additional requirements, removing existing requirements, modifying existing requirements, and adjusting stakeholder priorities. The method may also comprise the step of assigning in advance specific requirements to one of the next release, the next but one release, or unassigned before repeating the operations to the remaining. Repeating the step of operating on the stakeholder priorities or value estimates with the algorithms may comprise using the unassigned and new requirements as the requirements in the repeated step. According to a further aspect of the invention, the algorithms comprise one or more of genetic algorithms, heuristic algorithms and integer programming algorithms, and may use at least one objective function, which may comprise an aggregation of stakeholder priorities or value estimates, to evaluate release plan solutions. Computation of the algorithms may be carried out externally from an application service provider, and stakeholder priorities may be input to the computer from remote locations. According to a further aspect of the invention, selecting a release plan solution from the set of candidate release plan solutions is carried out by a problem solver. The method may also be carried out through a hybrid approach integrating computational intelligence and human intelligence. A set of maximally distinct alternative release plan solutions may be provided. Different use cases may be predefined. Process guidance may provided to perform the scenario use cases. According to a further aspect of the invention, the set of constraints is chosen from a group consisting of precedence relationships between requirements, coupling relationships between requirements, effort, resource, budget, risk, and time. Stakeholder priorities may be represented by a numerical value representing stakeholder satisfaction that a requirement be assigned to one of three categories, the categories consisting of the next release, the next but one release, and postponed. The requirements may be grouped into groups of requirements and the algorithms balance between stakeholder priorities assigned to the groups of requirements. Stakeholders may prioritize subsets of the complete set of requirements. According to a further aspect of the invention, an answer is provided on demand to questions chosen from a group of questions consisting of why requirements are assigned to a certain release, why requirements are not assigned to a certain release, which are commonalities in the proposed solutions, and which are differences in the proposed solutions. According to a further aspect of the invention, there is provided a computer programmed to carry out the invention, or computer readable media containing instructions for a computer to carry out the invention. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which: FIG. 1 is a flow chart of the release planning process; FIG. 2 is a diagram demonstrating the process of planning and developing of releases; FIG. 3 is a diagram demonstrating the various parts of EVOLVE*; FIG. 4 is a block diagram of crossover and mutation operators; FIG. 5 is a block diagram of a mutation operator; FIG. 6 is a block diagram of single chromosome elitism; FIG. 7 is a block showing fitness values and probabilities; FIG. 8 is a block diagram showing the calculation of a generation; FIG. 9 is a dependency graph; FIG. 10 is a graph of time versus cost of the evolution of solutions over three iterations; FIG. 11 is a graph of cost versus quality of the evolution of solutions over three iterations; FIG. 12 is a graph of time versus quality of the evolution of solutions over three iterations; FIG. 13 is a graph showing different software packages to be integrated; FIG. 14 is a graph showing different software packages in communication; FIG. 15 is a graph showing different software packages to be integrated with a middleware bus; FIG. 16 is a screenshot of the layout of requirement dependencies; FIG. 17 is a screenshot of the layout of stakeholders; and FIG. 18 is a screenshot of the layout of a generated plan. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the feature being present. In this patent document, we discuss features and requirements as main characteristics of a release plan. Features are considered to be a logical unit of behavior that is specified by a set of functional and quality requirements. In other words, features are an abstraction from requirements that both customers and developers understand. The topics discussed in this patent document are applicable to both the original requirements as well as to their aggregation into features and when either is referred to it will be understood that it applies to both, unless the context clearly indicates otherwise. While release planning specifically for software is discussed, it will be appreciated that the principles in this patent document are applicable to other situations that involve incremental releases, for example, IT, telecommunications, pharmaceuticals,.finance, transport, agriculture, or other projects such as oil and gas. Software release planning as formulated later in this patent document extends prioritization in five directions: Release planning is based on a set of (representative and most important) stakeholders which can input priorities from a remote place (don't need to attend a physical meeting), There is a formal procedure to balance all the stakeholder priorities to determine an overall prioritization result. As part of that, the degree of importance of the different stakeholders can be varied. Release planning takes into account (estimates of) the implementation effort. In addition, it can also handle constraints related to risk, money, or technological dependencies. Release planning considers the time of implementation by assigning features to (predefined or not) releases. The formal procedure of release planning is able to consider different criteria (urgency, importance) and to bring them together in a balanced way. Referring to FIG. 1, an exemplary embodiment of a method of release planning, indicated by general reference character 100, will now be discussed. In the first step 102, the requirements and/or features are identified. This step may also include a determination regarding the number and frequency of releases. In step 104, the set of constraints are defined, and in 106, stakeholder priorities are also assigned, as will be described in more detail below. For example, stakeholder priorities may be assigned by the stakeholders themselves using remote computers accessing a host computer over a network such as the internet. Alternatively, a wireless connection could be used to get access to the network, with a user interface prepared that is customized for handheld computing. The next step 108 is to use algorithms, namely computer based optimization algorithms such as genetic algorithms or integer programming, to explore release plan solutions that satisfy the constraints and balance between stakeholder priorities of different stakeholders. The exploration step 108 typically takes place at the host computer and generates a set of candidate release plan solutions that have a positive impact on at least one of project time, overall cost and quality as shown in step 110. The release plan solutions are evaluated by human intelligence in step 112, and outperformed release plan solutions are removed from consideration in step 114. In step 115, requirements are assigned to one of the three options, according to the analysis and information available to the decision maker. If a release plan solution is evident in step 116, we may then proceed to choose a solution in step 120. Because of all the inherent uncertainties and dynamic changes, this is unlikely to happen on the first iteration, and the constraints, stakeholder priorities and requirements are updated in step 116. Updating may include seeking further stakeholder input based upon requirements assigned to a specific release, or modifying the constraints to the new situation. Changing the requirements may also include adding additional requirements, removing existing requirements, or modifying existing requirements. Step 116 is optional, and merely allows the decision maker the opportunity to adjust the situation based upon changing circumstances or a better understanding of the problem. We then return to step 108 to operate once again on the priorities subject to the constraints. The process continues until a best choice release plan solution is evident. The overall process is supported by an explanation component. Throughout the release planning process, answers may be provided to the following questions: why are requirements assigned to a certain release? Why are requirements not assigned to a certain release? Which are commonalities in the proposed solutions? Which are differences in the proposed solutions? It will be apparent that the step described can be implemented by programming a computer or preparing computer readable media with instructions for a computer. Software project planning and management requires balancing competing objectives, managing risk, and overcoming constraints to successfully deliver a product that meets the needs of both customers and the users. The planning stage is based on decisions about which features should be implemented in which release—as provided by release planning. In other words, release planning results are the input for the more detailed project planning and later project management. 1. Formal Problem Statement 1.1 Requirements, Features and Constraints Release planning is based on an evolving set of features and requirements. The number of releases to be considered in advance may vary from case to case. We use “option k” for the assignment of a feature to increment k. Because of the high degree of requirements volatility, it does not make sense to plan too many releases in advance. For this embodiment, and without loss of generality, we will only consider two releases in advance. This is considered to be a good compromise of looking into the future while accepting the uncertainty and volatility of the problem. Consequently, as a result of release planning, each feature is assigned to exactly one of three possible cases: next release (option 1), next but one release (option 2), or postponed or not (yet) considered for implementation (option 3). Let F={f1, . . . , fn} be the set of features to be assigned to releases, which may also be referred to as increments. Whenever applicable without ambiguity, {1, 2, . . . , n} is used instead. As introduced above, release planning is distributing F into three categories: “next release” (option 1), “next but one release” (option 2), and “not yet decided” (option 3). Consequently, a release plan is characterized by a vector x of decision variables x=(x(1), x(2), . . . , x(n)) with x(j)=k if feature j is assigned to option k. Assignment of features to increments can't be done without considering the different types of dependencies. Dependencies between features are represented by relations defined on the product set F×F of F. We use the following six types of dependency between features: Type 1: i AND j if feature i requires feature j to function and vice versa. If two features are in Type 1 relationship then they must belong to the same increment. Type 2: i FREQ j if feature i requires feature j to function, but not vice versa. If two features are in Type 2 relationship then i should not be implemented in an earlier release than j. Type 3: i TREQ j if implementation of feature i requires implementation of feature j. If two features are in Type 3 relationship then i should be implemented in the same increment as j. Type 4: i CVALUE j if feature i affects the value of feature j. If two features are in Type 4 relationship then the value of the two in combination is different from the additive value (non-additive value functions) when applied in isolation. Type 5: i ICOST j if feature i affects the implementation of feature j. If two features are in Type 5 relationship then the effort of the two in combination is different from the additive value (non-additive effort function). Type 6: i IND j if feature i and feature j are in none of the first five types of dependencies. For the sake of simplicity, we assume that dependencies of types 4 and 5 are handled by synthesizing these features into a new (integrated) one. To model dependencies of types 1 to 3, we introduce a directed graph G(R)=(V(F), A(F)) with a set of vertices V(F) and a set of arcs A(F). Feature ii from a set of features F is represented by vertex set i ε V(F). The set A(F) of arcs is defined from dependencies of Type 1 to 3 as follows: Type 1: i AND j implies (i,j) ε A(F) and (j,i) ε A(F) Type 2: i FREQ j implies (i,j) ε A(F) Type 3: i TREQ j implies (i,j) ε A(F) With the graph G(F)=(V(F), A(F)), we can formulate dependency constraints as x(i)≦x(j) ∀ (i,j) ε A(F) In other words, we intend to restrict the number of dependencies between requirements and their assignment to different releases by some fixed degree of relative coupling between options. Alternatively to what is presented above, we may define a structural ratio bound called ‘Coupling’ and a related constraint as: Struc(x)=(# of edges of P between different options)/card(P)≦Coupling Release planning is impacted by a number of constraints. These constraints could be related to different aspects such as effort, risk, or budget. The effort to implement a requirement is hard to estimate. For the easiest case, we assume an effort function, effort: →R+ assigning to each feature an estimated effort for its implementation. As this effort is typically hard to predict, we assume that it is based on estimates such as the optimistic, the pessimistic and the most likely effort. For the sake of simplicity, we further assume an additive function for the implementation of set A⊂. We further assume an effort capacity bound Effort_Bound(k) for both the next two releases under consideration. This bound summarizes all the available resources for the different stages of development of a specific release product. From this resource perspective, all feasible release plans should fulfill the respective effort constraint for release options 1 and 2, e.g., Effort ( k , x ) := ∑ x ( i ) = k effort ( i ) ≤ Effort_Bound ( k ) for k = 1 , 2. In the same way, we can perform a risk evaluation for each feature. Risk estimation is used to address all the inherent uncertainty associated with the implementation of a certain feature. We employ a risk score as an abstraction of all risks associated with a given feature. These risks may refer to any event that potentially might negatively affect schedule, cost or quality in the final project results. For each feature i, ‘risk’ is an interval scaled function, risk: →[0,1), where ‘0’ means no risk at all and ‘1’ stands for the highest risk. In what follows we assume that the risk assessment is done by expert judgment. We further assume, that the risk is independent from the assigned release. The objective of risk balancing is to avoid a concentration of too many risky features in the same increment. The risk per increment is supposed to be additive, and Risk_Bound(k) denotes the upper bound for the acceptable risk for options 1 and 2. This leads to constraints Risk ( k , x ) := ∑ x ( i ) = k risk ( i ) ≤ Risk_Bound ( k ) for k = 1 , 2. In some cases, financial constraints are important as well (or even the most important constraint). From a purely monetary perspective, we assume an estimated financial effort required to realize feature i. For each feature i, ‘finance’ is an interval scaled function, finance: →R+ assigning to each feature an estimated amount of money for its implementation. As there is an available financial budget Finance_Bound(k) for both the next two releases under consideration, all feasible release plans have to fulfill Finance ( k , x ) := ∑ x ( i ) = k finance ( i ) ≤ Finance_Bound ( k ) for k = 1 , 2. Typically, project releases are planned for certain dates. This introduces a size constraint Sizek in terms of effort of any released increment Inc(k). We have assumed that the effort for an increment is the sum of the efforts required for individual requirements assigned to this increment. This results in another constraint: ∑ r ( i ) ∈ Inc ( k ) effort ( r i , R k ) ≤ Size k for all increments Inc ( k ) . A Releases may also be arranged according to open scope release planning, where release times are not predefined. If this approach is used, the definition of the release times and the requirements or features assigned to the respective releases are obtained as results. In this case, a solution may be sought that minimize the time between releases, since the earlier a release is issued, the earlier it generates value, such as money. Another point to consider is whether there are any sub-, or otherwise related, products. In this case, each may have its own release planning goals, however, for the overall products, the different cycles have to be synchronized. This can be modeled and solved using integer programming. The notion of ‘open scope planning’ can be extended to address synchronization of releases as requested in any kind of embedded product development where you have to address planning of different parts (hardware, software, middleware). Each of these components is an open scope problem. However, for the final product, planning for all the components has to be synchronized because of the mutual dependency between the components. The solution is approached through a formal description of the problem that uses binary variables and applying genetic and integer programming optimization algorithms. Another consideration is resource-driven release planning. For all the variants of release planning, consideration of available resources is crucial. Based on an up-front judgement of which requirements need which resources for their realization, feasible plans can be determined with respect to their implementation effort. Using all, or a selection of the constraints as introduced above, we are able to define feasibility of release plans. A release plan x is called feasible if it fulfills all the model constraints. The set of all feasible release plans is denoted by X. 1.2 Stakeholder Priorities 1.2.1 Stakeholder One of the challenges of software development is to involve stakeholders in the requirements engineering process. System stakeholders in the area of software engineering may be defined as people or organizations who will be affected by the system and who have a direct or indirect influence on the system requirements. This definition may be broadened or narrowed according to the situation. Effectively solving the problem of release planning involves satisfying the needs of a diverse group of stakeholders. Stakeholder’ examples are: user (novice, advanced, expert or other classifications of users, manager (project, product), developer, or sales representatives. Software engineering focuses on producing high-quality software products on time and within budget. However, there is a mutual dependency between the three dimensions. According to “The magic triangle”, any improvement in terms of either cost or time or quality is impacting the remaining ones. The challenge is to pro-actively investigate how to define and how to achieve a most appropriate balance. We assume q different stakeholders abbreviated by S1, S2, . . . , Sq. Each stakeholder Sp is assigned a relative importance λp ε (0,1). The relative importance of all involved stakeholders is typically assigned by the project or product manager. If it is difficult to actually determine these weights, pair-wise comparison using the analytic hierarchy process can be used as a support. We assume that stakeholder weights are normalized to one, i.e., Σp=1, . . . , q λp=1. We also assume that the requirements or features are understandable by all stakeholders and sufficiently detailed to estimate the effort for their implementation. It is understood that detailed descriptions are required, as those requirements that are poorly described are more likely to receive lower prioritizations from stakeholders. In addition, stakeholders will have different perspectives on the problem and different needs that must be addressed by the release plan. According to their main interest, they might focus more on quality, time, or benefit. Stakeholders may not be able or comfortable enough to rank all priorities. A stakeholder may therefore be considered active or inactive with respect to each requirement. Additionally, requirements may be described hierarchically, such as by grouping requirements into groups, where stakeholders may only look at a higher level of aggregation, based on their level of expertise, interest, or specialization. Let S={S1, . . . , Sr} be the set of stakeholders. Whenever applicable without ambiguity, {1, . . . , r} is used instead of {S1, . . . , Sr}. The set S is partitioned into three subsets S=St∪Sb∪Sq According to their respective focus on time (St), benefit (Sb) and quality (Sq). Within each category, a stakeholder Sp is given a relative importance (p) satisfying ΣpεStλp=ΣpεSbλp=ΣpεSqλp=1. There are different ways to express stakeholder prioritization of requirements. The concrete selection depends on the specific conditions and preferences. We give two example schemata: Prioritization schema type 1: The judgment of stakeholder p with regard to requirement i is denoted by Sat(p,i) where Sat(p,i) ε {1,2,3,4,5} can represent the perceived satisfaction. Prioritization schema type 2: For each requirement i, the stakeholder p is asked to represent his/her satisfaction with the situation that requirement i is assigned to option k (k=1,2,3). His/her judgment is expressed by Sat(p,i,k) ε {1, . . . , 9}. In total, each stakeholder has nine votes to distribute among three options, i.e., Σk=1,2,3 Sat(P,i,k)=9. The higher the number of votes (s)he assigns to k, the more satisfied (s)he would be if the requirement is put in the respective option. The increasing focus on value creation as a result of software development implies the question of the impact on value for the different features or requirements. Typically, there are different and conflicting priorities between different (groups of) stakeholders. To determine the most attractive feature and product portfolio's, priorities have to be evaluated to the best knowledge available. There are different ways to evaluate the ‘priority’ of a feature from a stakeholder perspective. Alternatively to the method presented above, two dimensions of priority may also be considered: a value-based, and an urgency-based prioritization. Value addresses the assumed impact on the value of the final product. Value here is considered to be independent of time. Urgency more addresses the time-to-market aspect, maybe, to reflect market needs and competitor analysis information. Intuitively, what we are trying to achieve is to assign features of high value and high urgency to first releases. We define two attributes for priority evaluation: 1.2.2 Value Value-based software engineering can help to identify a process in which value related decisions can be integrated in software engineering practices. It has been suggested that we can no longer afford to follow a value-neutral approach where software engineers treat every requirement, feature, use case, object, defect or other artefacts as of equal value; methods and practices are largely logical activities not primarily taking into account the creation of value; software engineers use earned-value systems to track project cost, schedule, but not stakeholder or business value; concerns are separated from software engineers' turning requirements into verified goals, and setting goals for improving productivity or correctness independent of stakeholder value considerations. There is no easy and crisp definition of value. It can be (i) a fair return or equivalent in goods, services, or money, or (ii) the monetary worth of something, or (iii) relative worth, utility or importance. Without being more precise about the concrete meaning, we expressed ‘value’ by a nine-point (ordinal) scale with increasing order of value corresponding to increasing value-based priority. The judgment of stakeholder p with regard to feature i is denoted by value(p,i) where value(p,i) ε {1, 2, . . . , 9} represents the perceived value of the feature i for stakeholder p. We are using a nine-point scale of measurement which could be replaced by another (e.g., five-point) scale in dependence of the degree of knowledge about the subject. The higher the number, the higher the perceived value of feature i. As a guideline and, we define value(p,i)=1 if feature i is of very low value value(p,i)=3 if feature i is of low value value(p,i)=5 if feature i is of moderate value value(p,i)=7 if feature i is of high value value(p,i)=9 if feature i is of extremely high value 1.2.3 Urgency We have introduced the three options on how to assign a feature to releases. Urgency addresses the degree of satisfaction with these three possible from the individual stakeholder perspective. Urgency can be motivated by time-to-market of certain product features. For each feature i, the stakeholder p is asked to represent his/her satisfaction with the situation that feature i is assigned to option k (k=1,2,3). His/her judgment is expressed by sat(p,i,k) ε {1, . . . , 9} with Sat ( p , i ) = ( sat ( p , i , 1 ) , sat ( p , i , 2 ) , sat ( p , i , 3 ) ) for all features i and all stakeholder p ∑ k = 1 , 2 , 3 sat ( p , i , k ) = 9 for all features i and all stakeholder p 1.3 Objectives and Formal Problem Statement The question of what actually constitutes a good release plan needs careful consideration. Intuitively, we are expecting most valued and most urgent features first. However, ‘most valued’ and ‘most urgent’ might mean different things for different types of stakeholder. The user is expecting features that he or she would need first to get started. But there are different types of users such as novice, advanced and expert users having different types of expectations and preferences. Potentially, there is a great variety of formally stated objective functions. Two examples are: Objective function type 1: Aggregation of all stakeholder opinions using a normalized weight vector w=(wt,wb,wq) with wt+wb+wq=1. In conjunction with prioritization schema type 1, the objective function F(x) is defined as Max F ( x ) = ∑ z = t , b , q w z ( ξ 1 ∑ x ( i ) = 1 WAS z ( i ) + ξ 2 ∑ x ( i ) = 2 WAS z ( i ) ) where ξ 1 + ξ 2 = 1 and WAS z ( i ) = ∑ p ∈ S z λ p Sat ( p , i ) denotes the weighted average satisfaction for requirement i from the perspective z=t (time), b (benefit), and q (quality). ξ1 and ξ2 are weights assigned by the project manager to options 1 and 2 (i.e. the two releases in consideration). Requirements assigned to the third option are not contributing to the objective function value. Objective function type 2: In this schema, objective functions related to time, benefit, and quality are handled independently. The problem is multi-objective and we use Max* to denote the search for “most promising” solutions. In conjunction with prioritization schema type 2, the objective function vector is defined as Max * { Sat t ( x ) , Sat b ( x ) , Sat q ( x ) } with Sat z ( x ) = ξ 1 ∑ i : x ( i ) = 1 WAS z ( i , 1 ) + ξ 2 ∑ i : x ( i ) = 2 WAS z ( i , 2 ) for z = t , b , q and WAS z ( i , k ) = ∑ p ∈ S z λ p Sat ( p , i , k ) for z = t , b , q and k = 1 , 2 Another proposition is a function combining the individual stakeholder evaluations from the perspective of value and urgency in a multiplicative way. For each feature i, we introduce the weighted average priority WAP(i,k) reflecting the product of the value and the urgency of stakeholders with respect to a fixed feature and a fixed option of assignment to releases. Typically, not necessarily all stakeholders are able or comfortable to give their evaluation related to all features. A stakeholder p is called active with respect to feature i, if (s) has provided the evaluation (and is called passive otherwise). The set of active stakeholders with respect to feature I is denoted by P(i). For determining WAP(i,k), the sum of all individual weighted products is divided by the sum of all active stakeholder weights. Further flexibility is introduced by the possibility to vary importance of stakeholder weights λp and to weight the importance ξ1 and ξ2 of options 1 and 2, respectively. This results in the objective function F(x) defined as F ( x ) = ξ 1 ∑ x ( i ) = 1 WAP ( i , 1 ) + ξ 2 ∑ x ( i ) = 2 WAP ( i , 2 ) with WAP ( i , k ) := [ ∑ p ∈ P ( i ) λ p · value ( p , i ) · sat ( p , i , k ) ] / [ ∑ p ∈ P ( i ) λ p ] for all features i and k = 1 and 2. For a fixed vector λ of stakeholder weights and a fixed vector of bounds, the release-planning problem RP(λ, bound) becomes Maximize F(x, λ, bound) subject to x ε X. However, what is more appropriate in real-world is to solve a sequence {RP(λ, bound)} of problems with varying parameters λ and bound. This solution set is typically small. From a solution set generated this way, the decision-maker can finally choose his or her most preferred solutions. A more detailed problem statement will now be presented. For all requirements ri ε Rk determine an assignment ω* with ω*(ri)=s ε {1, 2, . . . } to increments Incs such that ∑ r ( i ) ∈ Inc ( m ) effort ( r i , R k ) ≤ Size m for m = k , k + 1 , … ( Effort constraints ) ω * ( r i ) ≤ ω * ( r j ) for all pairs ( r i . r j ) ∈ Ψ k ( Precedence constraints ) ω * ( r i ) = ω * ( r j ) for all pairs ( r i . r j ) ∈ ξ k ( Coupling constraints ) A = ∑ p = 1 … , q λ p [ ∑ r ( i ) , r ( j ) ∈ R ( k ) penalty ( r i , , r j , S p , R k , ω * ) ] ⇒ min ! with penalty ( r i , , r j , S p , R k , ω * ) := 0 if [ prio ( r i , S p , R k ) - prio ( r j , S p , R k ) ] [ ω * ( r i ) - ω * ( r j ) ] > 0 prio ( r i , S p , R k ) - prio ( r j , S p , R k ) if ω * ( r i ) = ω * ( r j ) ω * ( r i ) - ω * ( r j ) if prio ( r i , S p , R k ) = prio ( r j , S p , R k ) [ prio ( r i , S p , R k ) - prio ( r j , S p , R k ) ] [ ω * ( r j ) - ω * ( r i ) ] otherwise Function A minimizes the total penalties defined as the degree of deviation of the monotonicity property between requirements. Monotonicity property between two requirements is satisfied if one requirement is evaluated more promising than another, and this is true also for the sequence of the assigned increments. B = ∑ p = 1 … , q λ p [ ∑ r ( i ) ∈ R ( k ) benefit ( r i , S p , ω * ) ] ⇒ max ! with benefit ( r i , S p , R k , ω * ) = [ ∂ - value ( r i , S p , R k ) + 1 ] [ τ - ω * ( r j , ) + 1 ] and τ = max { ω * ( r i ) : r i ∈ R k } Function B maximizes the total benefit. For a fixed stakeholder, the benefit from the assignment of an individual requirement to an increment is the product of some value difference and some difference in increment numbers. The product is the higher, the earlier the requirement is released and the more impact on final business value is supposed. C(α)=(α−1)A+αBmax! with α ε (0,1) The overall objective function C for one fixed value of α is to maximize a linear combination of A and B. The case of α close to 0 means to give a (strong) priority to stakeholder priorities. In a similar way, α close to 1 means a (strong) priority is given to the achieved benefits of assignment ω*. Determine K best solutions from C(α1), C(α2), C((α3) with 1≦K≦10 and 0<α1<α2<α3<1. In addition to those included above, other functions may be included to account for, for example, risk or size considerations. All optimal solutions determined from this approach are known to be non-dominated (Pareto-optimal). The limitation of this approach is that in case of non-convex problems, only solutions located at the convex hull in the objective space are determined. However, our emphasis is to generate a (small) set of promising solutions from which the decision-maker finally can select. As optimality can't be guaranteed anyway, this limitation is not a real restriction in our case. To offer a final set of K best solutions, three different values of α are considered. They reflect the different kinds of priorities including a balanced linear combination of the two criteria. The actual number K depends of the concrete problem. Typically, it will not require more than ten to provide an overview of the existing (most promising) solutions. Both K and the individual values of α are supposed to be determined by the actual decision-maker. 2. Solution Approach EVOLVE* We have observed that the problem of release planning is extremely difficult because of its inherent uncertainty, size and complexity. It is unrealistic to expect that this problem can be solved completely in one iteration. Instead, our strategy is to try to gradually reduce the size and complexity of the problem and to increase the validity of the underlying model. Finally, we get a set of candidate solutions with reasonable size to be considered in depth by the decision makers. The overall architecture of EVOLVE* is designed as an iterative and evolutionary procedure mediating between the real world problem of software release planning, the available tools of computational intelligence for handling explicit knowledge and crisp data, and the involvement of human intelligence for tackling tacit knowledge and fuzzy data. This is illustrated in FIG. 3. Referring to FIG. 3, the spiral curve describes the performance of EVOLVE*. At all iterations, three phases are passed: Phase 1—Modeling: Formal description of the (changing) real world to make it suitable for computational intelligence based solution techniques. This includes the definition of all decision variables, as well as their dependencies and constraints, and the description of what is, or contributes to, the “goodness” of a solution. Other data, such as stakeholder evaluation of all requirements, are also part of modeling. Phase 2—Exploration: Application of computational techniques to explore the solution space, to generate and evaluate solution alternatives. Exploration phase may be based on evolutionary computing, IP formulations or other optimization algorithms that use objective functions such as those set out above. In particular, exploration using IP formulations may use commercially available IP software, in which the objective functions indicated above are maximized subject to sets of constraints such as the constraints described in this patent document. Phase 3—Consolidation: Human decision maker is invited to investigate current solution alternatives. This contributes to the understanding of the problem and results in modifying parts of the underlying model or in some local decisions (e.g., pre-assigning some requirements to a release). Typically, these decisions reduce the size and complexity of the problem for the next iteration. 2.1 Hybrid Solution Approach EVOLVE*—Modeling The model to be used for EVOLVE* has already been discussed. Models in general are abstract and simplified descriptions of reality. According to the objectives and the specific topic under investigation, models are always focusing on specific aspects of reality. Many concerns have to be left out to keep the model tractable. Meaningful models are characterized by clarity, simplicity, validity, and tractability. However, such models are hard to achieve from a single and isolated effort. Instead, we consider modeling as an ongoing effort with evolving models that are becoming more and more meaningful for the purpose of its use. Modeling forms the basis for understanding and improving current reality. In general, meaningful results can only be achieved based on meaningful models. Equivalently, pure models will always imply pure results. For the problem of software release planning, modeling mainly comprises the definition of key variables, their dependencies, as well as definition of main objectives and constraints. 2.2 Hybrid Solution Approach EVOLVE*—Exploration The exploration phase is devoted to generate and evaluate solution alternatives. Generation of feasible assignments of requirements to releases in a changing environment taking into account different stakeholder perspectives is a problem of large complexity and size (including hundreds of requirements, large number of stakeholder, and high percentage of dependencies and constraints). One option in the exploration step is to use the computational power of evolutionary (or genetic) algorithms. Genetic algorithms have arisen from an analogy with the natural process of biological evolution. While IP (integer programming) types of algorithms guarantee optimality, they are hard to apply for very large scale problems. Genetic algorithms are particularly well suited to NP-complete problems that cannot be solved by deterministic polynomial algorithms. It has been empirically shown that genetic algorithms can generate high quality solutions being optimal or near optimal even for large-scale problems. Genetic algorithms maintain a population of solutions or chromosomes. A large population size improves the probability of obtaining better solutions and so should speed up the optimization process, although this is at the expense of computation time. Each member of the population receives a fitness measure, i.e., the value of the objective function. This measure relates to how good the chromosome is at solving the stated problem. Main operations applied to chromosomes of the population are selection, crossover, and mutation. Selection is effected by choosing two parents from the current population, the choice being determined by relating the fitness score to a probability curve. A more detailed description of genetic algorithms will be presented below. The idea of offering decision support always arises when decisions have to be made in complex, uncertain and/or dynamic environments. An exemplary solution approach EVOLVE* generates a typically small set X of most promising candidate solutions from which the actual decision-maker can choose from. This set X is further studied during the consolidation phase. The emphasis of decision support is on support, not on actually making the decision. In the real world, additional and most recent influencing factors or constraints are taken into account in making the decision. This is best achieved through maintaining a set of K-Best solutions. 2.3 Hybrid Solution Approach EVOLVE*—Consolidation The purpose of the consolidation phase is to structure and reduce the set of candidate solutions by applying human judgment and intelligence. This process is supported by intelligent techniques such as the principle of Concordance/Non-discordance and Information Theory. The key element in this phase is the intuition of the decision maker. This is where the decision maker can combine the results obtained from the model (the set X of most promising solutions) with his/her experience, knowledge, and expectation. All these aspects are assumed not to be part of the underlying formal decision model. To achieve a higher degree of conformance with reality, the decision maker can examine set X to judge if the proposed solutions are in accordance with his/her preference. If the discrepancy is important, this may lead to a revision of the model. Otherwise, s/he can use X as a support to make further decisions such as pre-assignment of some requirements to some options, i.e. to reduce the size and complexity of the problem. When the size and complexity of the problem are reduced to a level that can be reasonably solved by human decision makers, he can decide to stop the process. Otherwise, s/he continues with the next iteration (modeling, exploration, consolidation). When using X as a support to make further decisions, the decision maker can be assisted by the suggestions given by EVOLVE*. The first type of suggestion is due to the principle of Concordance/Non-Discordance. Intuitively, the principle suggests that if we have no formal reason to prove or disprove a proposition D then we can use the rule “If there are enough facts supporting the proposition D (concordance) and there is no fact strongly opposing it (non-discordance), then we should accept D”. More precisely, if there are at least c % solutions of X that agree on the assignment of requirement i to option k (x(i)=k) and there is no more than d % solutions of X that strongly disagree on this assignment then the decision x(i)=k is proposed. The second type of suggestion is inspired by an intuitive rule of thumb: “If there is at least one alternative from each of the (three) perspectives that agrees in a certain assignment of requirements to an option, then this option is worth to be further studied”. This type of suggestion is possible only when the model is multi-objective, i.e., the set X consists of the K best solutions in terms of each objective. Formally, X is partitioned into X=∪Xz, where Xz consists of the most promising solutions in terms of objective (criterion) z. If in each Xz, there exists a solution xz εXz that agrees on the assignment of requirement i to option k (xz(i)=k) then the decision x(i)=k is proposed. Another suggestion is to use the diversity of solutions. As explained, a core concept of solving release planning with all the inherent uncertainties is to offer a set of most promising solutions. In an ideal situation, where the objective function represent exactly the perception of the decision maker about the goodness of a solution and all the data collected are precise enough, there is no doubt that the best solution is the one given by the optimization model. However, most situations, particularly with the release planning problem, are far from being ideal. Therefore, to give a better support for the decision maker, it is more reasonable to propose a set of solutions instead of just one. The decision maker can use the part of knowledge that cannot be taken into account by the model to make the final decision. The principle of maximal diversity states “it is good to provide a decision maker with more options, it is better if these option are different”. Naturally, the notion of diversity is based on the “similarity” or “distance” between two solutions. By introducing thresholds on the different objectives and introducing Euclidean distances between solutions, a set of maximally distinct alternative release plan solutions can be determined with the existing algorithms. Here, we can use Euclidean distance δ ( X , X ′ ) = ∑ i = 1 , n ( X ( i ) - X ′ ( i ) ) 2 We use the following procedure to implement the principle of maximal diversity as follow. Let k be the number of solutions expected to propose to the decision maker. Step 1: Determine a Set CX of Near Optimal Solutions (Perhaps From Different Perspectives) |CX|>k To determine a set of near-optimal candidate solutions, the decision maker has to vary parameters such as the relative importance of increments, the weights of the stakeholders or the weights Wz for different perspectives if he/she wants to combine these three perspectives. It is very difficult to give these values. One option is to ask some judgments such as: stakeholder 1 is “a little more important” than stakeholder 10; the group of stakeholders St is “much more important” than Sq. Then try different ways to perceive the “goodness” (corresponding to different parameters and even objective functions). For each of them, choose the best (or the K-best) solution(s). Step 2: Determine the Set of L Near-Optimal Solutions Having the Maximal Distance Among Them. Formally, we have the following model: Max D ( FX ) = ∑ X , X ′ ∈ FX δ ( X , X ′ ) FX ⋐ CX Card ( FX ) = L ( fixed ) . Besides these suggestions, the decision maker can also consider other decision variables. As there is no clear suggestion from the analysis of X, these decisions are made mainly from his/her own judgment. To facilitate the choice of a variable to concentrate on, we can rank the decision variables from the most to the least conflicting. We represent the conflicting level by the “entropy” of the variable. Ent(x[i])=−p1log2(p1)−p2log2(p2)−p3log2(p3), where pk=|{x εX, x[i]=k}|/|X|, k=1,2,3 and 0log20:=0. Intuitively, if most of the solutions in X agree on the assignment of requirement i to option k then the conflicting level of this decision is low. 2.4. Genetic Algorithms Genetic algorithms have arisen from an analogy with the natural process of biological evolution. They are particularly well suited to NP-complete problems that cannot be solved by deterministically polynomial algorithms. One commonly discussed problem area to which genetic algorithms have been applied is the Travelling Salesman Problem (TSP). It has been empirically shown that genetic algorithms can generate high quality solutions being optimal or near optimal even for large-scale problems. In the area of software engineering, this approach was successfully applied to devise optimal integration test orders. Genetic algorithms are maintaining a population of solutions or chromosomes. A solution or chromosome is a set of requirements ordered for implementation. A population is a number of different chromosomes. The ‘optimal’ population size is a matter for debate. Some have suggested higher populations while others indicate that population sizes as low as thirty are adequate. A large population size improves the probability of obtaining better solutions and so should speed up the optimization process, although this is at the expense of computation time. Each chromosome or member of the population receives a fitness measure, i.e., the value of the objective function, such as one of the objective functions mentioned above. This measure relates to how good the chromosome is at solving the stated problem. The genetic algorithm applies a series of operations to the population of chromosomes in order to obtain a set of chromosomes with relatively high scores (fitness values) as indicated by the objective function corresponding to the chromosome. Main operations applied to chromosomes of the population are selection, crossover, and mutation. Referring to FIG. 4, selection is effected by choosing two parents from the current population. The choice is determined by relating the fitness score to a probability curve, as seen in FIG. 7, where the higher the fitness, the higher the probability. The crossover operator takes two parents, randomly selects items in one parent and fixes their place in the second parent (for example, items B and D in FIG. 4). These are held in position but the remaining items from the first parent are then copied to the second parent in the same order as they were in originally. If an item has already been used, that item is skipped, and we continue on with the next item. In this way some of the sub-orderings are maintained. Generally, a crossover may be accomplished by randomly selecting two points which become fixed in the second parent, as well as all items between these two points. Items from the first parent are inserted around the fixed portion in the order they appear. As multiples of the same requirement cannot exist, if a requirement is already present in the fixed portion, it is skipped, and the next requirement used in its place, until all requirements have been used, and all spaces filled in the new member of the population. Mutation is carried out after crossover and is intended to introduce variance and so avoid terminating at a local solution. FIG. 5 shows an example of mutation, where the third and fourth genes are switched. Mutation introduces new orderings in the population that might not be reached if only crossover operations were used. Since the values in the chromosome must remain constant, the normal approach to mutation where one or more variables are randomly changed will not work. Hence, mutation is effected via random swapping of items in the new offspring. The number of swaps is proportional to the mutation rate. After a new chromosome has been produced, we check to make sure it is still valid according to the constraints that were previously defined. This ensures that each plan we generate is a valid one. An example is shown in FIG. 4. Chromosome 1 and 2 are selected, and undergo crossover as described previously. The new offspring is ranked in the current population and the bottom ranked chromosome is discarded. Hence the population size retains a steady state. The extent of mutation is controlled by the parameter mutation rate. The choice of ‘best’ mutation and crossover rates is sensitive to the type of problem and its characteristics. At each generation, members of the population are assessed for fitness. Different solutions result in different fitness scores depending on how they balance the priorities of the stakeholders. Frequently in using genetic algorithms this fitness refers to a cost function that has to be minimized or a payoff function that should be maximized. The processes of evaluation, selection, crossover and mutation continue, and the net effect is a gradual movement towards higher fitness scores in the population. Since genetic algorithms operate on a population rather than a single entity, the possibility of becoming stuck at local optima is reduced. The choice of when to terminate the algorithm may be determined by a predefined number of iterations, a preset elapsed time or when the overall improvement becomes negligible. As stated above, each member of the population is assessed for fitness. Referring to FIG. 7, a higher fitness value FV, which is obtained form the objective functions, translates into a higher probability P that the member will be used in an operation. For example, in a pool of fifty, the top 20 members may have a combined probability of 75% of being chosen, while the other 30 have a 25% probability of being chosen. In this way, more fit members will be used more frequently to generate the next generation, while the unfit members are more likely to be removed from the pool. The number of member in the pool is kept constant. Referring to FIG. 8, an example of a generation being calculated is used, where the arrows represent selection. There are options that can be used in implementing the genetic algorithm. For example, referring to FIG. 6, single chromosome elitism may be used, which ensures that the best member stays in the pool for the next generation. Another option is seeding the algorithm at the beginning by a member generated by using what can be termed a greedy algorithm, by including it in the other randomly generated members. This generates a solution by sorting the requirements by the results of the objective function at the beginning. The solution is then reordered as little as possible such that it satisfies the constraints. This allows the good traits of the greedy plan to profligate through the population, often speeding the process of finding an optimized solution. Another option is single point crossover, where a single point is chosen, and the genes above or below that point are fixed, while genes from the other parent are inserted into the offspring in the order that they appear, removing the duplicated genes. Each member of the pool contains all requirements. Once a solution is arrived at, the preferred member may be divided up into the releases based on constraints, such as time, effort, and budget using a bin packing strategy. Starting at one end, requirements are included in the order that they appear until the next requirement will not satisfy the constraint. The next requirements are examined to see if they are less demanding and if they are able to satisfy the constraints. In this way, the resources are more efficiently used. 3. Embodiment Example As an example, an embodiment of the invention with key features will be described as a tool suite that provides a flexible and web-based tool support for assigning requirements or features to releases such that most important risk, resource, and budget constraints are fulfilled. It can be used in different user modes and aims in providing intelligent decision support for any kind of iterative development. It addresses the wicked character of the problem by an approach integrating computational and human intelligence, based on EVOLVE*. Main features of the tool are: General Features Portability: Browser-based tool enabling early and comprehensive stakeholder involvement Compatibility and interoperability (with MS Excel, MS Project) Flexibility: The tool is able to solve a wide range of problem types (in terms of prioritization scheme, objective function, and constraints) Ease of use: State-of-the art menus support easy understanding and a steep learning curve Scalability: Tool supports projects with a wide range of problem size. Security: Version control, access control, password protection and file level control, protection of highly sensitive data Applicability: Wide range of applications in any kind of phased or incremental product development in IT, logistic, pharmacy, oil and gas, banking, agriculture, telecommunication, and health care. Rapid response time by usage of customized implementations of optimization algorithms Specific Features Capabilities for grouping of requirements Possibility of pre-assignment of requirements to releases Coupling and precedence constraints between requirements Consideration of effort Consideration of resource, budget and risk constraints Flexibility in voting: scale of voting (3,5,9-point scale) Flexibility in type of voting (prio-based, value-based, both) Flexibility in number of increments Incomplete voting Customer-specific access to hierarchical requirements Generation of a set of ‘most promising’ solutions Reporting capability Generation of a set of ‘near optimal’ and “maximally distinct’ solution alternatives Process guidance following predefined usage scenarios Explanation on demand on specific characteristics of solutions (Explanation component) Stakeholder analysis determining commonalities and differences in stakeholder prioritization (Stakeholder analysis component) Graphical output of stakeholder analysis Import and export functionality Graphical output of set of most promising release plans In addition, answers may be provided on demand to questions such as why requirements are assigned to a certain release; why requirements are not assigned to a certain release; which are commonalities in the proposed solutions; and which are differences in the proposed solutions. Explanation is intended to increase acceptance of the tool, to improve understanding of the results, and to increase applicability and acceptance of suggested solutions. When a planner or decision maker makes a plan or reaches a decision then the presentation of just the solution itself is often insufficient. This is in particular the case if the decision is done by a black box system where complex calculations and much knowledge are involved. In such a situation two problems arise: (i) the user often has no insight in the major reasons that lead to the presented solution. In particular, if the solution is somewhat surprising the user has difficulties to accept it. Therefore, the user may not trust and may not accept the solution; and (ii) because of the lack of understanding, the user is not able to give feedback. In particular, the user cannot mention that certain parts mentioned in the explanation are not valid in the specific situation of the problem. These problems are due to the fact that the user has limited knowledge about fundamental problem understanding, the knowledge and information units relevant for obtaining the solution and the way such units are combined for finding the solution. In such a situation an explanation is usually helpful. An explanation can fail to reach this goal for the following reasons: the explanation is incomplete, i.e. relevant aspects are missing; the explanation is too detailed, in particular it mentions too many facts that are known to the user or technical details; or explanation is not understandable by the user. The release planner explanation scenario involves three types of agents (participants): the system that provides the solution to the problem: In our context a software agent; the user who obtains the solution for further treatment, in out context a human agent; and the explainer who explains the system's solution to the user, in our context a software agent. Here we are interested in the explainer agent. The explanation agent needs knowledge about the other agents. More precisely, the explainer needs an understanding of how the system obtains the solution, and a model of the user. A user model in general describes (i) What the user knows and (ii) What the user wants or needs to know. In some way, one can think of an explanation as an answer to (yet) unexpressed questions of the customer; therefore somehow the concept of a dialog enters the scenario. In particular, it gives again rise to distinguish to types of explanations: a) One-step explanations, provided only once, and b) Dialog-type explanations that proceed in several steps. Both types contain a communication aspect, for a) it is degenerated. In general, the amount of explanation as requested is given during release planning. This means, more details are only provided if the user demands them. In particular, no routine operations are explained but rather decisions that look surprising to the user. The strategy is hence guided by the user who therefore plays the active role in the dialog. 3.1 Usage Scenarios Use cases describe a sequence of actions that the system will perform to achieve an observable result of value for the user. Described below are some use case scenarios. In addition, the use cases may be graphically animated to facilitate usage of the tool and understanding of the value of the tool. Process guidance may be utilized in the use cases. This means that the user will decide for a certain scenario, and will be guided through the sequence of actions to be performed in the use case by, for example, a wizard telling what to do next. Process guidance may also include a knowledge or lessons learned repository where certain knowledge, lessons learned or templates for documentation are provided from previous experiences during the release planning process. 3.1.1 Stakeholder Priority Analysis Background: Mismatch of customer satisfaction still with the functionality of the delivered software is one of the main reasons that software projects fail. To achieve better customer satisfaction, their early involvement is crucial. In globally performing companies, stakeholders (including the different types of customer) are distributed all over the world. Having a large number of potential features and a larger number of stakeholders, the question of defining typical patterns of priorities. As a kind of pre-analysis, data mining is used to detect commonalities and differences in stakeholder prioritization of features. This scenario is aiming to better understand stakeholder preferences without actually performing the release planning. It is expected that results are varying in dependence of different classes of stakeholders (e.g., different groups of users, different roles in the overall product development process, different customer regions). Main benefit here is to enable and efficiently gather a large set of stakeholder preferences. As the tool is web-based, the scenario is cheap and guick. The result provides essential information to address main customer needs. The scenario is applicable for both new product development and for maintenance-type extension of an existing product. Input: All stakeholders are asked to present their priority evaluation. The evaluation is based on the description of the features (or requirements). The overall information is secured and is only visible by the product (or project) manager. Output: Main differences and commonalities in feature priorities of the different (groups of) stakeholder. 3.1.2 Operational Planning and Re-Planning Background This scenario is aimed to better understand the problem and the impact of the problem parameters. A number of different parameter combinations are studied to analyze the results and compare them with the constraints and possibilities of the real world. This scenario will typically apply fast heuristic algorithms that are generating good, but not necessarily optimal solutions. As a results of this scenario, the decision-maker will get a more transparent understanding of the problem objectives and constraints. Where are the project bottlenecks? What has to be provided to achieve certain goals? This problem understanding is important because it is a prerequisite to generate meaningful models and meaningful results. The same principle is applied for the case of re-planning. As problem and project parameters change quite frequently, it is important to optimally adjust to new situations. This process is time-consuming and failure-prone if done in an ad hoc fashion. Again, the scenario is applicable for both new product development and for maintenance-type extension of an existing product Input: In addition to the input of the scenario “Stakeholder priority analysis”, the product or project manager inputs different possible options (or changes) for the following variables: Available effort, Available (bottleneck) resources, Available time intervals for the releases, Risk profile of the releases, and Pre-assignment of features to releases (as a ramification of a performed competitor analysis) Weight (importance) of individual stakeholders. Output: Best solution alternatives in dependence of the different scenarios. Detection and explanation of their commonalities and differences. Detection and explanation of project bottlenecks. 3.1.3 Customer-Optimal Product Portfolio's Background This scenario aims in defining the appropriate product portfolio for an assumed set of key customers with evolving feature requirements. This product family could be part of a software product line. Product lines are characterized as a family of (software) products. The members of the family are variants having a set of common features. The process of scoping tries to find out all the tentative features. This could happen by a workshop with main customers describing their expectations of the product features. Different variants of the same product family can be seen as releases. As there is some technological dependency between them, the process of defining the “most appropriate” portfolio of products can be modeled as a release-planning problem. This scenario could be supported by any kind of collaborative environment. In the easiest case, this could be a teleconference. The product or project manager guides and moderates the process. The intelligence of the tool is the backbone for making proposals on how to balance the conflicting stakeholder interests. Input All stakeholders are asked to present their priority evaluation. Stakeholders here are mainly potential clients or customers. Their assumed importance can be expressed by their respective individual weights. Any type of technological dependency between features has to be modeled as well as the estimated effort for each of the features. The process can be performed in a batch mode or (highly interactive with different sequences of possible parameters) in a workshop type session. Output Optimal strategies for product portfolio's. For a product line, design of release and their optimal sequence are defined. Independent of product lines, an optimal (or near-optimal) sequence of products is generated that addresses the different priorities of an existing customer base. 3.1.4 Cyclic Planning for Competing Objects Under Resource and Technology Constraints Background The notion of release planning can be applied to any type of cyclic product planning. Annual planning of projects or, in general, selection between competing objects are typical examples of that. All these plans are looking ahead for the next one, two or more cycles. In addition, constraints as the ones introduced in section 2 have to be satisfied. Output Formally, the input is the same as for the scenarios above: Available effort, Available (bottleneck) resources, Risk profile Weights of stakeholder Stakeholder evaluation of objects. Output Optimal or near-optimal plans for the cycles in consideration. 3.1.5 Synchronization of Releases Background In the case of a product that is composed out of individual sub-products, release planning can be applied to different parts separately. These parts could be related to hardware, middle-ware and software components. To release a version of the product, all the releases of the sub-product have to be synchronized. Non-synchronized release plans would result in a situation where the delivery of the product is delayed whenever one of its inherent parts is delayed. Input Any of the scenarios of above can be applied, but all information is provided for all the individual sub-products. Output Synchronized release plans provide optimal performance for the integrated product. All the release plans of the individual sub-products are adapted to achieve final synchronization. Enterprise Application Integration (EAI) Planning Background EAI enables an enterprise to integrate its existing applications and systems and to add new technologies and applications to the mix. EAI also helps an enterprise to model and automate its business processes. Integration technology enables organizations to improve their business processes while retaining more value from their existing investments, thereby increasing their business agility and improving efficiency. By using EAI, big companies can save as much as 80 percent of the cost of doing a custom integration project. Input Available resources to be integrated become the requirements, and the constraints defined above are adapted to the specific situation. Stakeholder priorities are obtained for which constraints are to be integrated in what order. Output A release plan for the order of integration of the various priorities. 4. Case Studies Software Release Planning We consider an example with 30 requirements and three stakeholders. Each stakeholder represents exactly one of the objectives related to time, benefit, and quality. Therefore St={S1}, Sb={S2}, Sq={S3} and λ1=λ2=λ3=λ1. Initially, the data collected consist of the effort estimation for each requirement and the dependencies among them represented by two binary relations, C (coupling) and P (precedence). All these dependencies are represented by a dependency graph G=(V, E, A) shown in FIG. 9. G is a mixed graph with vertices corresponding to requirements and edges (i,j) ε E if requirements i and j are in coupling relation C. In the same way, arc (i,j) ε A if requirements i and j are in precedence relation P. The capacities available are Cap(1)=120 (next release) and Cap(2)=90 (next but one release) units of effort (e.g., person days). We demonstrate the course of iterations with the three phases described above from the perspective of the actual project manager (PM). Our emphasis here is not so much on the numerical part of the problem solution. Instead, because of its inherent vagueness and uncertainty we are focusing on the evolution of the understanding of the problem, the model evolution, and the progress that is made during iterations to solve the proposed problem. Modeling (Iteration 1): At first, the PM has to decide on the prioritizing scheme. The consultation with the stakeholders goes to the consensus on the voting scheme (prioritization scheme type 2) because of its simplicity and its applicability. For the objective function, the PM decides to consider all three competing objectives (time, benefit, quality) separately. The reason of this choice is that the tradeoff among these three perspectives is rather complicated; the use of this scheme helps preserving these perspectives so that the tradeoff can be handled more carefully. Thus the objective function type 2 is chosen. Exploration (Iteration 1): The PM uses a computer to run a genetic algorithm of the type described here to explore the proposed model. An alternative is to use an IP formulation. From exploring the proposed model, the PM obtains a list of the most promising solutions (release plans) from each perspective. Each solution will contain a particular balance of stakeholder priorities, and will be a feasible solution according to the constraints of the model. S/he picks up 5 best solutions from each perspective to form the set X=Xt∪Xb∪Xq. The result is resumed in Table 1 at the end of this patent document. Each column (1-15) corresponds to a solution in X. The group of first five columns Xt (respectively Xb, Xq) represents the 5 best solutions from the perspective time (respectively benefit, quality). Row ‘Satt’ (respectively ‘Satb’, ‘Satq’) gives the value of objective function from time (respectively benefit, quality) perspective. Row ‘Struc’ is the number of P-edges between different increments (the total number of elements in P is 15). Consolidation (Iteration 1): After verifying that the solutions in X are in compliance with his/her expectation, the PM proceeds with the analysis of X. The first type of suggestion: The PM decides that a suggestion is worth his/her attention if it is supported by at least 13 out of 15 solutions and not strongly opposed by any solution. With this rule, s/he obtains 19 suggestions. The second type of suggestion: The application of the rule “If there is at least one alternative from each of the (three) perspectives that agrees in a certain assignment of requirements to an option, then this option is worth to be further studied” results in eight suggestions how to assign requirements to releases. Details of the analysis are summarized in Table 2. Initially, the PM considers the 19 suggestions of the first type. In general, s/he accepts these suggestions except some special cases where some new factors (not taken into account by the model) intervene. Finally, 17 suggestions are accepted. Requirement 29 is highly rated by the stakeholders, but the PM observes that the effort required is rather high (25 units) and the risk associated seem very high too (this is a qualitative judgment). Therefore, s/he decides to assign it to option 3 (postponed). Another requirement, 24, is not very well rated by the stakeholders (suggested to be assigned to option 3). However, the PM “feels” that this requirement has an important influence on the implementation of other requirements. Since s/he is still not sure, this decision is postponed. The PM feels uncertain concerning the other eight suggested assignment options. This is justified by two reasons: the discussion with the stakeholders does not lead to a consensus; the PM does not want to advance too fast and therefore, s/he wants to see the impact of his/her last decisions before continuing the process. At the end of the first iteration, 18 requirements have been assigned. Because of the inherent uncertainty and vagueness, there are still 12 requirements to be considered. That means the size of the problem is considerably reduced. Modeling (Iteration 2): The PM decides to continue with the same underlying model as in iteration 1. As the PM has made some decisions that are different from the suggestions, it is necessary to run iteration 2 to observe the effect of these decisions (if the PM chooses to accept the all the suggestions, these decisions only reduce the set X; and there is no need to run iteration 2). Exploration (Iteration 2): This time, the solution space has become smaller; the PM observes that in each perspective, the 4th best solution is “far away” from the “best one” in term of the values of the corresponding objective function, i.e. it is no longer necessary to consider this solution as promising. Therefore, s/he decides to pick up only three most promising solutions from each perspective (Table 3). Again, a genetic algorithm, IP formulation or other optimization process is used to explore the solution space and find solutions with a balance between stakeholder priorities which are favorable according to a fitness measure. Consolidation (Iteration 2): This time, the rule used for the first type of suggestions is “If a suggestion is supported by at least 8/9 solutions and not strongly opposed by any solution, then it is worth our attention”. Again, these suggestions are summarized in the Table 4. There are 9 suggestions, but only 4 decisions are made. The PM decides to assign {8,9} to option 2 instead of option 1 as suggested by the formal algorithm. S/he also realizes that the four other suggestions (second type) are not easy to tackle all at the same time. It is more reasonable to concentrate on some issues. S/he decides to consider the least conflicting issues (requirements 16, 20, 27 with entropy =0.8). After a thorough examination and discussion, s/he decides to assign requirement 20 to option 1 as suggested, requirement 27 to option 3 instead of 1 and postpone the decision concerning requirement 16. At the end of this phase, there are still only 8 requirements to consider. Modeling (Iteration 3): There is no new change to the model except the last three decisions reducing the size of the problem to 9 decision variables. Exploration (Iteration 3): Again, due to the reduction of the solution spaces, s/he picks up only two best solutions from each perspective. However, certain solutions are among the best in more than one perspective; finally, the PM can choose only three solutions which are resumed in Table 5. We observe that solution 1 is the best from all three perspectives. Consolidation (Iteration 3): The size of X is so small (only 3 solutions) that its analysis does not provide a better insight of the problem. Within a set of three solutions, a rule based on the concept of “majority” seems not very convincing. The PM has two options: to continue with a more sophisticated model or to stop. For the rest of the problem, the issues to consider are the most subtle, and there are many other factors to take into account. The first option would be very time consuming and could not assure an appropriate solution. Furthermore, the size of the problem has been considerably reduced. S/he decides that the rest of the problem be handled by human decision makers through an adequate negotiation process. S/he decides to just eliminate the solution 2 since the structure index is rather high (10) and accepts the two other solutions as the most promising ones for further consideration. The evolution of the set of most promising solutions taken over all three iterations is summarized in FIGS. 10, 11 and 12. To facilitate the observation of the evolution, a 3-dimension presentation (time, cost, quality) is replaced by the three 2-dimensional graphs. We observe that a better conformance of the proposed solution is achieved to the disadvantage of the formal value of the objective functions. This is due to the overall uncertainty of the problem situation and the increasingly better problem understanding achieved by the synergy of computational and human intelligence. Enterprise Application Integration (EAI) Planning Example Most sites invest heavily on software packages. As shown in FIG. 13, they may have customer care systems 132, order management systems 134, and billing systems 136, among others. These may be already in place and working. All of these will have been purchased (or written) to address a particular business need or function, and they are all very good at what they do. Systems 132, 134, and 136 have their own view of how the business works and together they help us run our business. However, there is little or no communication between them. They each work as individual packages—doing what they do and that's that. Let's just consider this example and think through how we could enable some of these packages to communicate and be more integrated with each other. As indicated in FIG. 14, to enable the customer care system 132 to see if orders have been placed by any new customers, we could write a batch job that: Interrogates the customer database 144 of the order management system 134 When it finds a new customer it could enter these details into the customer database 143 within the customer care system 132 To enable the order management system 134 to automatically kick off a new billing once the order has been fulfilled, we could write a batch job that: Scans the orders database tables 145 to see any completed orders for that day Looks up the customer information from the orders customer database 144 and with all the necessary information it could make an entry into the appropriate database tables 146 within the billing system 136 To enable the billing system 136 to manage billing issues, we could write a batch job that: Gets billing history Retrieves all the billing records for the given customer from the billing customer database 147 Besides the above integration requirements, two translators 142 and 148 are needed: Translator 142 to translate new customers from the order management system to the customer care system 132 Translator 148 to translate new billings from the order management system 134 to the billing system 136 However, in order to make the integration extendable with other systems and applications in the future, referring to FIG. 15, it is better to use a middleware 150 who has its own common language with which each individual system can communicate with. Therefore, the communication between systems can be achieved easier and more efficient. Accordingly, the need of the above two translators 142 and 148 shifts to three translators 152, 154, and 156: Write customer care translator 152 from the customer care system to an agreed common language to facilitate communications between systems Write order management translator 154 from the order management system to an agreed common language to facilitate communications between systems Write billing translator 156 from the billing system to an agreed common language to facilitate communications between systems Besides serving as a common or generic language, the middleware 150 is also able to facilitate the translators to be plugged in and to make calls to other translators on it. In FIG. 16, a screenshot from the tool ReleasePlanner™ shows the layout of requirement dependencies. The precedence and coupling dependencies identified above are highlighted in the rectangles. The screenshot shows the tool as a web-based tool. There are different kinds of stakeholder who have the judgment on which requirement should be implemented in which release of application integration. Their judgments base on their different perspectives and interests. Stakeholders can be: Sales representative User (novice, immediate, advanced, expert) Investor Shareholder Project manager Product manager Developer In this EAI scenario, we choose user, project manager, product manager as the example stakeholders involved in the planning of integration. These stakeholders have different priority on the requirement evaluation. We use the 0˜9 scale to demonstrate their importance. The larger the number is, the more important the corresponding stakeholder is. An example screenshot of stakeholders in ReleasePlanner™ is shown in FIG. 17. After finishing the input of all the above release planning data, release plans can be generated by choosing the function “Generate a Plan” in the ReleasePlanner™. Various plans that can meet the constraints defined previously can be generated one by one. In this example, we generated three different valid release plans. These plans provide intelligent guidance to the involved people on how to plan the application integration more efficiently and accurately. They may be analysed later in the step “Consolidation” and the most suitable solution will be chosen as the actual integration plan to follow. One of the generated plans is shown in FIG. 18. In order to interpret the plan results, we take release plan 1 as the example. The requirements from the identified requirement set are assigned into different releases. For every release, the sum of effort of every requirement in that release is no great than the maximum effort available for that release. Nine requirements are assigned into release one, taking 295 person-days' effort. Another ten requirements are in the release two with the total effort of 300 person-days. Four requirements are postponed to implement. Within every release, both functional and non-functional requirements are assigned to make sure the Also, the release planning results conform t0o the requirement dependencies identified in the previous step, modeling. For example, we identified the coupling dependency between R 1 and R 22, and precedence dependency that R 9 must be implemented before R 1. We can see that the plan 1 follows these predefined constraints. What's more, this result takes account of the evaluation from different stakeholders who have different importance in making such evaluation. The higher the vote a requirement can get, the more likely that it can be implemented in the earlier releases. Immaterial modifications may be made to the embodiments of the invention described here without departing from the invention. Tables TABLE 1 Results of the exploration and consolidation phases of iteration 1. The numbers represent a relative measure of the degree of satisfaction of all 15 solutions with respect to the three criteria. 5-best solutions from the 3 stakeholder perspectives Solution 1 2 3 4 5 6 7 8 9 1 1 1 1 1 1 Satt 74 74 7 7 7 7 7 7 7 7 7 7 7 7 7 Satb 78 77 7 7 7 7 7 7 7 7 7 7 7 7 7 Satq 81 82 8 7 7 8 8 7 8 8 8 8 8 8 8 Struc 8 9 7 9 9 9 7 7 8 8 8 8 7 7 7 TABLE 2 Analysis of solution set X and comparison of suggested and decided options during iteration 1 (U means uncertainty to make the decision at that stage). First type Second type of suggestions of suggestions Requirements {29} {21, 22 {1, 2, 12, {3, 4, 5, 6, {24} {8, 9, {10, 11, {26, 28, 0} 13, 14} 7, 17, 19, 23} 18} 16} 27} Suggested 1 1 2 3 3 1 2 3 Decided 3 1 2 3 U U U U TABLE 3 Results of the exploration and consolidation phases (iteration 2). 3-best solutions from the 3 stakeholder perspectives Solution 1 2 3 4 5 6 7 8 9 Satt 7 71 7 6 6 6 6 70 69 Satb 6 69 7 7 7 7 7 74 69 Satq 7 78 7 7 7 7 7 79 80 Struc 9 9 8 6 7 9 8 6 8 TABLE 4 Analysis of open decisions related to X and actual decisions made in iteration 2. First Second type Requirement {8, 9} {15, 16} {18, 25, 26} 20 27 Suggested option 1 2 1 1 1 Decided option 2 U U 1 3 TABLE 5 Results of iteration 3. Solution Solution Solution Satt 67 67 66 Satb 68 65 67 Satq 76 74 75 Stru 9 10 9 | <SOH> BACKGROUND OF THE INVENTION <EOH>Requirements management in general is concerned with the control of system requirements that are allocated to software to resolve issues before they are incorporated into the software project. It aims to accurately adjust plans and cost estimates as the requirements change, and to prioritize requirements according to their importance and their contribution to the final value of the product. There is very good reason to significantly improve the maturity of these processes. According to the Standish Research Group (“What are your requirements?” http://www.standishgroup.com/, 2002), the three leading causes of quality and delivery problems in software projects are related to requirements management issues: Lack of adequate user input, incomplete requirements and specifications, and changing requirements specifications. A software release is a collection of new and/or changed features or requirements that form a new product. Release planning for incremental software development assigns features to releases such that most important technical, resource, risk and budget constraints are met. Without good release planning ‘critical’ features are jammed into the release late in the cycle without removing features or adjusting dates. This might result in unsatisfied customers, time and budget overruns, and a loss in market share, as indicated by Penny D., “An Estimation-Based Management Framework for Enhancive Maintenance in Commercial Software Products”, in Proc. International Conference on Software Maintenance, 2002. “Developing and releasing small increments of requirements, in order for customers to give feedback early, is a good way of finding out exactly what customers want, while assigning a low development effort” as stated in Carlshamre, P., “Release Planning in Market-Driven Software Product Development: Provoking an Understanding”. In: Requirements Engineering 7, pp 139-151, 2002. There is a growing recognition that features act as an important organizing concept within the problem domain and as a communication mechanism between users and developers. They provide an efficient way to manage the complexity and size of requirements. The concept of a feature is applicable and important for any software development paradigm. However, it is especially important for any type of incremental product development. Features are the “selling units” provided to the customer. Incremental development has many advantages over the traditional waterfall approach. First, prioritization of features ensures that the most important features are delivered first. This implies that benefits of the new system are realized earlier. Consequently, less important features are left until later and so, if the time or budget is not sufficient, the least important features are the ones most likely to be omitted. Second, customers receive an early version of the system and so are more likely to support the system and to provide feedback on it. Third, the schedule and cost for each delivery stage are easier to estimate due to smaller system size. This facilitates project management and control. Fourth, user feedback can be obtained at each stage and plans can be adjusted accordingly. Fifth, an incremental approach is sensitive to changes or additions to features. Agile methods as described in Cockburn, A., “Agile Software Development”, Pearson Education, 2002, have capitalized on the above advantages. In Extreme Programming (Beck, K. “Extreme Programming Explained”, Addison Wesley, 2001), a software product is first described in terms of ‘user stories’. These are informal descriptions of user requirements. In the planning process, these stories are prioritized using the perceived value to the user and assigned to releases. Based on estimates of how long each story in an increment will take to implement, an iteration plan is developed for delivering that release. Each increment (or release) is a completed product of use to the customer. At any time, new stories may be added and incorporated into future releases. The requirements engineering process is a decision-rich problem solving activity (Aurum, A., Wohlin, C., “The Fundamental Nature of Requirement Engineering Activities as a Decision-Making Process”, Information and Software Technology 2003, Vol. 45 (2003), No. 14, pp. 945-954.) One of the most prominent issues involved in incremental software development is to decide upon the most promising software release plans while taking into account diverse qualitative and quantitative project data. This is called release planning. The input for the release planning process is a set of features that are evolving due to changing user requirements and better problem understanding. Despite the obvious importance of the problem in current incremental and evolutionary development, it is poorly studied in the literature. Release planning considers stakeholder priorities and different types of constraints. The output of the release planning process is a set of candidate assignments of features to increments. They are supposed to represent a good balance between stakeholder priorities and the shortage of resources. In each increment, all the features are executed following one of the existing software development paradigms including analysis, system design, detailed design, implementation, component testing, system testing, and user testing. All the features are inputted into this process. As a result, a usable (release) product is provided. This fundamental procedure of planning and development of releases is illustrated in FIG. 2 . Release planning assigns features to release options 1 (dark grey), 2 (grey) or 3 (white). Within each release development cycles, all features are passing the stages of a software development cycle. This cycle includes verification and validation activities at the different product stages (requirement, system design, component design, code). At the end of this process, a verified and validated release product is delivered. This principle can be easily extended to planning of more than two releases ahead. Without any technological, resource, risk and financial constraints, all the features could be implemented in one release. However, the existence of all the constraints implies the questions: what comes first and why? The goal of release planning is to account for all these factors and to come up with suggestions for the most satisfactory release plans. There are two fundamental types of release planning problems: (i) release planning with fixed and pre-determined time interval for implementation, and (ii) planning with flexible intervals. In the second problem, you also decide about the length of the interval to implement all the assigned features. This type of planning is also called ‘Open scope release planning’. Software Release Planning adds to two well-established disciplines of (incremental) software development: (i) requirements management, especially requirements prioritization, and (ii) software project planning and management. Defining the commonalities and differences between them helps to better understand release planning. Requirements management is the process of identifying, documenting, communicating, tracking and managing project requirements as well as changes to those requirements. As requirements are changing, or are becoming better understood, or new requirements are arising, requirements management is an ongoing activity. Requirements prioritization is trying to determine the different degrees of priority. The problem of still delivering a large amount of features that are never used, and vice versa, not delivering those that are required, has (among others) to do with a lack of understanding and prioritization. As a feature has different relevant attributes (such as its functionality, inherent risk, effort of implementation) that contribute to the final judgement, requirements prioritization is a multi-attributive decision problem. Practically, most emphasis is on the provided functionality of the feature. Specifically, requirements prioritization is also a multi-person (multi-criteria) decision problem, as the prioritization is typically performed in a team-session. There is no clear description on how the different and conflicting opinions are actually negotiated. Release planning may be characterized as “wicked”. That means that the objective is “to maximize the benefit”, but it is difficult to give a measurable definition of “benefit”. Wicked problems have no stopping rule in its solution procedure. The underlying model is “evolving”: the more we study the problem, the more sophisticated the model becomes. Wicked problems have better or worse solutions, but no optimal one. Although we are approximating the reality, implicit and tacit judgment and knowledge will always influence the actual decisions. As a consequence of all these difficulties, we propose to rely on the synergy between computational strength and the experience and intelligence of the human decision maker as proposed by the paradigm of software engineering decision support. Release planning is a very complex problem including different stakeholder perspectives, competing objectives and different types of constraints. Release planning is impacted by a huge number of inherent constraints. Most of the features are not independent from each other. Typically, there are precedence and/or coupling constraints between them that have to be satisfied. Furthermore, effort, resource, and budget constraints have to be fulfilled for each release. The overall goal is to find a relatively small set of “most promising” release plans such that the overall value and the degree of satisfaction of all the different stakeholders are maximized. The topic of investigation is uncertain and incomplete in its nature: Features are not well specified and understood: There is usually no formal way to describe the features and requirements. Non-standard format of feature specification often leads to incomplete descriptions and makes it harder for stakeholders to properly understand and evaluate features and requirements. Stakeholder involvement: In most cases, stakeholders are not sufficiently involved in the planning process. This is especially true for the final users of the system. Often, stakeholders are unsure why certain plans were suggested. In the case of conflicting priorities, knowing the details of compromises and why they were made would be useful. All these issues add to the complexity of the problem at hand and if not handled properly, they create a huge possibility for project failures Change of features and requirements and other problem parameters: Features and requirements always change as the project progresses. If a large number of features increase the complexity of the project, their dynamic nature can pose another challenge. Other parameters such as the number of stakeholders, their priorities, etc., also change with time—adding to the overall complexity. Size and complexity of the problem: Size and complexity are major problems for project managers when choosing release plans—some projects may have hundreds or even thousands of features. The size and complexity of the problem (known to be NP-complete), and the tendency for not involving all of the contributing factors, makes the problem prohibitively difficult to solve by individual judgment or trial and error type methods. Uncertainty of data: Meaningful data for release planning are hard to gather and/or uncertain. Specifically, estimates of the available effort, dependencies of features, and definition of preferences from the perspective of involved stakeholders are difficult to gauge. Availability of data: Different types of information are necessary for actually conducting release planning. Some of the required data are available from other information sources within the organization. Ideally, release planning is incorporated into existing Enterprise Resource Planning or other organizational information systems. Constraints: A project manager has to consider various constraints while allocating the features and requirements to various releases. Most frequently, these constraints are related to resources, schedule, budget or effort. Unclear objectives: ‘Good’ release plans are hard to define at the beginning. There are competing objectives such as cost and benefit, time and quality, and it is unclear which target level should be achieved. Efficiency and effectiveness of release planning: Release plans have to be updated frequently due to changing project and organizational parameters. Ad hoc methods help determine solutions but are far behind objective demands. Tool support: Currently, only general-purpose tools for features management are available. Most of them do not focus on the characteristics of release planning. Solution Methods and Techniques Prioritization in general answers the questions to classify objects according to their importance. This does not necessarily imply a complete ranking of all objects, but at least an assignment to classes like ‘Extremely important’, ‘important’, or ‘of moderate importance’. Different scales are applicable according to the underlying degree of knowledge you have about the objects. Prioritization always assumes one or a collection of criteria to actually perform the process. In Karlsson, J., Wohlin, C and Regnell, B., “An Evaluation of Methods for Prioritising Software Requirements”, Information and Software Technology 39 (1998), pp 939-947, a requirements prioritization session is characterized by three consecutive stages: Preparation: Structuring of the requirements according to the principles of the method to be applied. Provide all information available. Execution: Agreement on criteria between all team members. Decision makers do the actual prioritization with all the information available. In general, this step needs negotiation and re-iteration. Presentation: Final presentation of results to those involved in the process. There are a number of existing approaches to requirements prioritization. The most important ones have been studied and compared in Karlsson et al. (referenced above). Among them are the analytic hierarchy process (AHP), binary search tree creation, greedy-type algorithms and other sorting-based methods. As a result of their evaluation, they have found out that AHP is the most promising approach. Most of those algorithms need O(n 2 ) comparisons between the n requirements. This effort required soon becomes prohibitive for larger number of requirements. In addition to that, none of the mentioned algorithms takes into account different stakeholder perspectives. The Analytic Hierarchy Process (AHP) is a systematic approach to elicit implicit preferences between different involved attributes, as discussed in Saaty T. L.: The Analytic Hierarchy Process, Wiley, New York, 1980. For the purpose of this investigation, AHP is applied to determine the importance of the various stakeholders from a business perspective. In addition, it is used to prioritize the different classes of requirements from the perspective of each stakeholder. The two preference schemata are combined to judge rank the importance of the different classes of requirements for the final business value of the software product. AHP assumes that the problem under investigation can be structured as an attributive hierarchy with at least three levels. On At the first level, the overall goal is described. The second level is to describes the different competing criteria that refining the overall goal of level 1. Finally, the third level is devoted to be used for the selection from competing alternatives. At each level of the hierarchy, a decision-maker performs a pair-wise comparison of attributes assessing their contributions to each of the higher level nodes to which they are linked. This pair-wise comparison involves preference ratios (for actions) or importance ratios (for criteria). The expert assigns an importance number that represents the importance of a term t i with respect to another term t j to describe the domain. Priority decisions become more complicated in the presence of stakeholders having different relative importance and different preferences. It becomes very hard in the presence of constraints about sequencing and coupling of requirements in various increments, and taking into account resource allocation for implementation of requirements. None of the methods mentioned above can be applied under these circumstances. Amongst the informal approaches claiming to handle release-planning, one of the most well known ones is ‘planning games’ as used in agile development. The goal of this approach is to deliver maximum value to the customer in least time possible. In half to one day long sessions, customers write story cards describing the features they want, while developers assign their estimates to those features. The customers then choose the most promising story cards for the next increment by either setting a release date and adding the cards until the estimated total matches the release date, or selecting the highest value cards first and setting the release date based on the estimates given on them. This simplistic approach works well in smaller projects. However, as the size and the complexity of the projects increases, the decisions involved in release planning become very complex. Various factors come into play, such as the presence of stakeholders having different relative importance and different preferences, the presence of constraints about sequencing and coupling of requirements in various increments, and the need to take into account resource allocation issues for implementing the requirements. Considering problems involving several hundreds of requirements and large number of widely scattered stakeholders, it becomes very hard to find appropriate solutions without intelligent support tools. The goal of such support is to account for all these factors in order to come up with a set of most promising release plans. | <SOH> SUMMARY OF THE INVENTION <EOH>There is therefore provided, according to an aspect of the invention, a method of release planning. The method comprises the steps of assigning stakeholder priorities to a set of requirements, where the priorities are assigned by plural stakeholders; explicitly defining a set of constraints on the requirements; and using algorithms carried out by a computer, exploring release plan solutions that satisfy the constraints and balance between stakeholder priorities of different stakeholders to generate a set of candidate release plan solutions that have a positive impact on at least one of project time, overall cost and quality; and selecting at least one release plan solution from the set of candidate release plan solutions. The solution may be further qualified by applying a concordance/non-discordance principle. A set of near optimal and maximally distinct solutions may also be generated. Operating on the stakeholder priorities with algorithms using a computer may be carried out repeatedly after changing one or more of the constraints, requirements or stakeholder priorities, which may comprise actions chosen from a group consisting of adding additional requirements, removing existing requirements, modifying existing requirements, and adjusting stakeholder priorities. The method may also comprise the step of assigning in advance specific requirements to one of the next release, the next but one release, or unassigned before repeating the operations to the remaining. Repeating the step of operating on the stakeholder priorities or value estimates with the algorithms may comprise using the unassigned and new requirements as the requirements in the repeated step. According to a further aspect of the invention, the algorithms comprise one or more of genetic algorithms, heuristic algorithms and integer programming algorithms, and may use at least one objective function, which may comprise an aggregation of stakeholder priorities or value estimates, to evaluate release plan solutions. Computation of the algorithms may be carried out externally from an application service provider, and stakeholder priorities may be input to the computer from remote locations. According to a further aspect of the invention, selecting a release plan solution from the set of candidate release plan solutions is carried out by a problem solver. The method may also be carried out through a hybrid approach integrating computational intelligence and human intelligence. A set of maximally distinct alternative release plan solutions may be provided. Different use cases may be predefined. Process guidance may provided to perform the scenario use cases. According to a further aspect of the invention, the set of constraints is chosen from a group consisting of precedence relationships between requirements, coupling relationships between requirements, effort, resource, budget, risk, and time. Stakeholder priorities may be represented by a numerical value representing stakeholder satisfaction that a requirement be assigned to one of three categories, the categories consisting of the next release, the next but one release, and postponed. The requirements may be grouped into groups of requirements and the algorithms balance between stakeholder priorities assigned to the groups of requirements. Stakeholders may prioritize subsets of the complete set of requirements. According to a further aspect of the invention, an answer is provided on demand to questions chosen from a group of questions consisting of why requirements are assigned to a certain release, why requirements are not assigned to a certain release, which are commonalities in the proposed solutions, and which are differences in the proposed solutions. According to a further aspect of the invention, there is provided a computer programmed to carry out the invention, or computer readable media containing instructions for a computer to carry out the invention. | 20040324 | 20110823 | 20050929 | 75676.0 | 0 | WANG, BEN C | RELEASE PLANNING | MICRO | 0 | ACCEPTED | 2,004 |
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10,807,604 | ACCEPTED | Transistor backplanes for liquid crystal displays comprising different sized subpixels | A display and a method for manufacturing said display is disclosed wherein said display is comprised of at least a first set of subpixels and a second set of subpixels—said first set of subpixels comprising smaller area than said second subpixels. The thin film transistors that drive said first set of subpixels are formed substantially in the area of said second set of subpixels. | 1. A display comprising: a plurality of first subpixels; a plurality of second subpixels, wherein said first subpixels have a smaller size than said second subpixels; a plurality of transistors driving said first and said second subpixels wherein said transistors for said first subpixels are formed in the area of said second subpixels. 2. The display of claim 1 wherein said plurality of first subpixels comprise a first color filter and said plurality of second subpixels comprise a second color filter and a third color filter. 3. The display of claim 2 wherein said second color filter is blue and said plurality of transistors driving said plurality of said first subpixel are formed in said blue color filtered subpixels. 4. A method for manufacturing in a LCD display wherein said LCD display comprises at least a first set of subpixels and a second set of subpixels wherein said first set of subpixels comprise a smaller area than said second set of subpixels and further wherein said first and said second subpixels are driven by a set of thin film transistors; the steps of said method comprising: forming a thin film transistor backplane such that a plurality of thin film transistors driving a subset of said first set of subpixels are formed substantially in the area of said second set of subpixels. 5. The method of claim 4 wherein said method further comprises the first set of subpixels comprises the green subpixels of said display. 6. The method of claim 4 wherein said method further comprises the first set of subpixels comprise the blue subpixels of said display. 7. The method of claim 4 wherein said method further comprises the thin film transistors are formed in a subset of said second set of subpixels, said subset of said second set of comprising substantially blue subpixels. | BACKGROUND In commonly owned United States patent applications: (1) U.S. patent application Ser. No. 09/916,232 (“the '232 application”), entitled “ARRANGEMENT OF COLOR PIXELS FOR FULL COLOR IMAGING DEVICES WITH SIMPLIFIED ADDRESSING,” filed Jul. 25, 2001; (2) U.S. patent application Ser. No. 10/278,353 (“the '353 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH INCREASED MODULATION TRANSFER FUNCTION RESPONSE,” filed Oct. 22, 2002; (3) U.S. patent application Ser. No. 10/278,352 (“the '352 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH SPLIT BLUE SUB-PIXELS,” filed Oct. 22, 2002; (4) U.S. patent application Ser. No. 10/243,094 (“the '094 application), entitled “IMPROVED FOUR COLOR ARRANGEMENTS AND EMITTERS FOR SUB-PIXEL RENDERING,” filed Sep. 13, 2002; (5) U.S. patent application Ser. No. 10/278,328 (“the '328 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS WITH REDUCED BLUE LUMINANCE WELL VISIBILITY,” filed Oct. 22, 2002; (6) U.S. patent application Ser. No. 10/278,393 (“the '393 application”), entitled “COLOR DISPLAY HAVING HORIZONTAL SUB-PIXEL ARRANGEMENTS AND LAYOUTS,” filed Oct. 22, 2002; (7) U.S. patent application Ser. No. 01/347,001 (“the '001 application”) entitled “IMPROVED SUB-PIXEL ARRANGEMENTS FOR STRIPED DISPLAYS AND METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING SAME,” filed Jan. 16, 2003, each of which is herein incorporated by reference in its entirety, novel sub-pixel arrangements are disclosed for improving the cost/performance curves for image display devices. For certain subpixel repeating groups having an even number of subpixels in a horizontal direction, the following systems and techniques to affect proper dot inversion schemes are disclosed and are herein incorporated by reference in their entirety: (1) U.S. patent application Ser. No. 10/456,839 entitled “IMAGE DEGRADATION CORRECTION IN NOVEL LIQUID CRYSTAL DISPLAYS”; (2) U.S. patent application Ser. No. 10/455,925 entitled “DISPLAY PANEL HAVING CROSSOVER CONNECTIONS EFFECTING DOT INVERSION”; (3) U.S. patent application Ser. No. 10/455,931 entitled “SYSTEM AND METHOD OF PERFORMING DOT INVERSION WITH STANDARD DRIVERS AND BACKPLANE ON NOVEL DISPLAY PANEL LAYOUTS”; (4) U.S. patent application Ser. No. 10/455,927 entitled “SYSTEM AND METHOD FOR COMPENSATING FOR VISUAL EFFECTS UPON PANELS HAVING FIXED PATTERN NOISE WITH REDUCED QUANTIZATION ERROR”; (5) U.S. patent application Ser. No. 10/456,806 entitled “DOT INVERSION ON NOVEL DISPLAY PANEL LAYOUTS WITH EXTRA DRIVERS”; (6) U.S. patent application Ser. No. 10/456,838 entitled “LIQUID CRYSTAL DISPLAY BACKPLANE LAYOUTS AND ADDRESSING FOR NON-STANDARD SUBPIXEL ARRANGEMENTS”; and (7) U.S. patent application Ser. No. 10/696,236 entitled “IMAGE DEGRADATION CORRECTION IN NOVEL LIQUID CRYSTAL DISPLAYS WITH SPLIT BLUE SUBPIXELS”, filed Oct. 28, 2003. These improvements are particularly pronounced when coupled with sub-pixel rendering (SPR) systems and methods further disclosed in those applications and in commonly owned United States patent applications: (1) U.S. patent application Ser. No. 10/051,612 (“the '612 application”), entitled “CONVERSION OF RGB PIXEL FORMAT DATA TO PENTILE MATRIX SUB-PIXEL DATA FORMAT,” filed Jan. 16, 2002; (2) U.S. patent application Ser. No. 10/150,355 (“the '355 application”), entitled “METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH GAMMA ADJUSTMENT,” filed May 17, 2002; (3) U.S. patent application Ser. No. 10/215,843 (“the '843 application”), entitled “METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH ADAPTIVE FILTERING,” filed Aug. 8, 2002; (4) U.S. patent application Ser. No. 10/379,767 entitled “SYSTEMS AND METHODS FOR TEMPORAL SUB-PIXEL RENDERING OF IMAGE DATA” filed Mar. 4, 2003; (5) U.S. patent application Ser. No. 10/379,765 entitled “SYSTEMS AND METHODS FOR MOTION ADAPTIVE FILTERING,” filed Mar. 4, 2003; (6) U.S. patent application Ser. No. 10/379,766 entitled “SUB-PIXEL RENDERING SYSTEM AND METHOD FOR IMPROVED DISPLAY VIEWING ANGLES” filed Mar. 4, 2003; (7) U.S. patent application Ser. No. 10/409,413 entitled “IMAGE DATA SET WITH EMBEDDED PRE-SUBPIXEL RENDERED IMAGE” filed Apr. 7, 2003, which are hereby incorporated herein by reference in their entirety. Improvements in gamut conversion and mapping are disclosed in commonly owned and co-pending United States patent applications: (1) U.S. patent application Ser. No. 10/691,200 entitled “HUE ANGLE CALCULATION SYSTEM AND METHODS”, filed Oct. 21, 2003; (2) U.S. patent application Ser. No. 10/691,377 entitled “METHOD AND APPARATUS FOR CONVERTING FROM SOURCE COLOR SPACE TO RGBW TARGET COLOR SPACE”, filed Oct. 21, 2003; (3) U.S. patent application Ser. No. 10/691,396 entitled “METHOD AND APPARATUS FOR CONVERTING FROM A SOURCE COLOR SPACE TO A TARGET COLOR SPACE”, filed Oct. 21, 2003; and (4) U.S. patent application Ser. No. 10/690,716 entitled “GAMUT CONVERSION SYSTEM AND METHODS” which are all hereby incorporated herein by reference in their entirety. Additional advantages have been described in (1) U.S. patent application Ser. No. 10/696,235 entitled “DISPLAY SYSTEM HAVING IMPROVED MULTIPLE MODES FOR DISPLAYING IMAGE DATA FROM MULTIPLE INPUT SOURCE FORMATS”, filed Oct. 28, 2003 and (2) U.S. patent application Ser. No. 10/696,026 entitled “SYSTEM AND METHOD FOR PERFORMING IMAGE RECONSTRUCTION AND SUBPIXEL RENDERING TO EFFECT SCALING FOR MULTI-MODE DISPLAY” filed Oct. 28, 2003; which are all hereby incorporated by reference. All patent applications mentioned in this specification are hereby incorporated by reference in their entirety. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in, and constitute a part of this specification illustrate exemplary implementations and embodiments of the invention and, together with the description, serve to explain principles of the invention. FIG. 1 is an example of a display comprising a subpixel repeating unit wherein there are at least two subpixels comprising different sizes and/or dimensions and an associated TFT backplane. FIG. 2 is one example of a display comprising at least two subpixels having different sizes/dimensions with a TFT backplane as made in accordance with the principles of the present invention. FIG. 3 is one example of an implementation of a TFT backplane as made in accordance with the principles of the present invention. FIG. 4 is another example of an implementation of a TFT backplane as made in accordance with the principles of the present invention. DETAILED DESCRIPTION Reference will now be made in detail to implementations and embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In commonly-owned applications listed above, there are shown display panels comprising a subpixel repeating group that further comprises subpixels of different physical dimensions. One example is shown in FIG. 1. A portion of display panel 100 is depicted here as comprising an octal repeating subpixel grouping 102 that comprises a checkerboard of red subpixels 104 and blue subpixels 108. These red and blue subpixels are larger in width that the four interspersed green subpixels 104. Each subpixel is shown as being driven by a thin film transistor (TFT) 110 in one of the corners of the subpixel. It may not be desirable to locate these TFTs in the corner of the smaller subpixels for several reasons. First, as the smaller subpixels are impacted in their aperture ratio more greatly than the larger subpixels, it might be desirable to locate their TFTs elsewhere. Second, at sufficiently high dots per inch (DPI), defects in the manufacture of TFTs for smaller sized subpixels might adversely impact the overall yield of panels having different sized subpixels. This may be especially true for amorphous silicon (a-Si) displays having pixel densities at or above approximately 150 dpi. This may be adversely impact aperture ratio because of the relatively large TFT used in a-Si. Additionally, there may be some defects that arise in mask misalignments that result in the smaller (in this example, green) subpixels being more impacted over most of the panel than the larger (e.g, red and blue) subpixels. Such misalignments may create a color shift overall and could be corrected by tuning the backlight for such defective panels or by designing the manufacturing process to create up to a certain level of mask misalignment. However, moving the TFTs into the larger subpixels might alleviate to some degree the overall color shifting that might occur with mask misalignments. It should be appreciated that the principles of the present invention are applicable to any subpixel layout having subpixels of different size. In fact, the number of subpixels in the repeating group and their color assignments may be any desired and chosen. It suffices that there are merely at least two subpixels that have different sizes/dimensional for the purpose of the present invention. Additionally, it might be desirable to locate all smaller subpixel TFTs into larger subpixel areas; or it may be desirable to locate a subset of such smaller subpixel TFTs into larger subpixel areas. It suffices that some of such smaller subpixel TFT are formed and located into larger subpixel areas. Thus, the scope of the present invention should not be limited to the particular examples of such layouts disclosed in the drawings and the specification. FIG. 2 depicts one embodiment of an improved TFT layout for displays comprising subpixels of different sizes. In this embodiment, the transistors in the smaller sized subpixels are moved to reside in the area of the larger subpixels. For example, in FIG. 2, it is seen that TFT 202 drives a red subpixel and blue subpixel 212 comprises TFTs 204, 206 and 208—which might drive subpixels 210, 212 and 214. In this embodiment, the aperture ratio of the blue subpixels would be impacted more than either the smaller, green subpixels or the larger red subpixel. This arrangement might be desirable, as the color blue has less emphasis in the human visual system. Of course, it would be appreciated that other embodiments would also be suitable. For example, the red subpixels could contain all or one extra TFTs to help drive the smaller subpixels. Additionally, the plurality of TFTs placed inside the larger subpixel may be placed in different locations (e.g. lower side or different corners) of the subpixel. Additionally, other color assignments for the larger and the smaller subpixels could be arranged. As stated above, it merely suffices that there are at least two different sized subpixels of any color and that some or all of the TFTs that would drive the smaller subpixels are constructed in the areas of the larger subpixels. FIGS. 3 and 4 show two possible embodiments for implementations of TFTs that drive proximate smaller subpixels within a larger subpixel—such as for subpixel 212 in FIG. 2. As may be seen, subpixels 210 and 214 are driven by TFTs 204 and 208 that are located with the space allocated to subpixel 212 in both FIGS. 3 and 4. It should be appreciated that neither FIG. 3 or 4 are drawn to scale here. Additionally, it should be appreciated that there are many other possible TFT designs that would suffice for the purposes of the present invention. While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. | <SOH> BACKGROUND <EOH>In commonly owned United States patent applications: (1) U.S. patent application Ser. No. 09/916,232 (“the '232 application”), entitled “ARRANGEMENT OF COLOR PIXELS FOR FULL COLOR IMAGING DEVICES WITH SIMPLIFIED ADDRESSING,” filed Jul. 25, 2001; (2) U.S. patent application Ser. No. 10/278,353 (“the '353 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH INCREASED MODULATION TRANSFER FUNCTION RESPONSE,” filed Oct. 22, 2002; (3) U.S. patent application Ser. No. 10/278,352 (“the '352 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH SPLIT BLUE SUB-PIXELS,” filed Oct. 22, 2002; (4) U.S. patent application Ser. No. 10/243,094 (“the '094 application), entitled “IMPROVED FOUR COLOR ARRANGEMENTS AND EMITTERS FOR SUB-PIXEL RENDERING,” filed Sep. 13, 2002; (5) U.S. patent application Ser. No. 10/278,328 (“the '328 application”), entitled “IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS WITH REDUCED BLUE LUMINANCE WELL VISIBILITY,” filed Oct. 22, 2002; (6) U.S. patent application Ser. No. 10/278,393 (“the '393 application”), entitled “COLOR DISPLAY HAVING HORIZONTAL SUB-PIXEL ARRANGEMENTS AND LAYOUTS,” filed Oct. 22, 2002; (7) U.S. patent application Ser. No. 01/347,001 (“the '001 application”) entitled “IMPROVED SUB-PIXEL ARRANGEMENTS FOR STRIPED DISPLAYS AND METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING SAME,” filed Jan. 16, 2003, each of which is herein incorporated by reference in its entirety, novel sub-pixel arrangements are disclosed for improving the cost/performance curves for image display devices. For certain subpixel repeating groups having an even number of subpixels in a horizontal direction, the following systems and techniques to affect proper dot inversion schemes are disclosed and are herein incorporated by reference in their entirety: (1) U.S. patent application Ser. No. 10/456,839 entitled “IMAGE DEGRADATION CORRECTION IN NOVEL LIQUID CRYSTAL DISPLAYS”; (2) U.S. patent application Ser. No. 10/455,925 entitled “DISPLAY PANEL HAVING CROSSOVER CONNECTIONS EFFECTING DOT INVERSION”; (3) U.S. patent application Ser. No. 10/455,931 entitled “SYSTEM AND METHOD OF PERFORMING DOT INVERSION WITH STANDARD DRIVERS AND BACKPLANE ON NOVEL DISPLAY PANEL LAYOUTS”; (4) U.S. patent application Ser. No. 10/455,927 entitled “SYSTEM AND METHOD FOR COMPENSATING FOR VISUAL EFFECTS UPON PANELS HAVING FIXED PATTERN NOISE WITH REDUCED QUANTIZATION ERROR”; (5) U.S. patent application Ser. No. 10/456,806 entitled “DOT INVERSION ON NOVEL DISPLAY PANEL LAYOUTS WITH EXTRA DRIVERS”; (6) U.S. patent application Ser. No. 10/456,838 entitled “LIQUID CRYSTAL DISPLAY BACKPLANE LAYOUTS AND ADDRESSING FOR NON-STANDARD SUBPIXEL ARRANGEMENTS”; and (7) U.S. patent application Ser. No. 10/696,236 entitled “IMAGE DEGRADATION CORRECTION IN NOVEL LIQUID CRYSTAL DISPLAYS WITH SPLIT BLUE SUBPIXELS”, filed Oct. 28, 2003. These improvements are particularly pronounced when coupled with sub-pixel rendering (SPR) systems and methods further disclosed in those applications and in commonly owned United States patent applications: (1) U.S. patent application Ser. No. 10/051,612 (“the '612 application”), entitled “CONVERSION OF RGB PIXEL FORMAT DATA TO PENTILE MATRIX SUB-PIXEL DATA FORMAT,” filed Jan. 16, 2002; (2) U.S. patent application Ser. No. 10/150,355 (“the '355 application”), entitled “METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH GAMMA ADJUSTMENT,” filed May 17, 2002; (3) U.S. patent application Ser. No. 10/215,843 (“the '843 application”), entitled “METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH ADAPTIVE FILTERING,” filed Aug. 8, 2002; (4) U.S. patent application Ser. No. 10/379,767 entitled “SYSTEMS AND METHODS FOR TEMPORAL SUB-PIXEL RENDERING OF IMAGE DATA” filed Mar. 4, 2003; (5) U.S. patent application Ser. No. 10/379,765 entitled “SYSTEMS AND METHODS FOR MOTION ADAPTIVE FILTERING,” filed Mar. 4, 2003; (6) U.S. patent application Ser. No. 10/379,766 entitled “SUB-PIXEL RENDERING SYSTEM AND METHOD FOR IMPROVED DISPLAY VIEWING ANGLES” filed Mar. 4, 2003; (7) U.S. patent application Ser. No. 10/409,413 entitled “IMAGE DATA SET WITH EMBEDDED PRE-SUBPIXEL RENDERED IMAGE” filed Apr. 7, 2003, which are hereby incorporated herein by reference in their entirety. Improvements in gamut conversion and mapping are disclosed in commonly owned and co-pending United States patent applications: (1) U.S. patent application Ser. No. 10/691,200 entitled “HUE ANGLE CALCULATION SYSTEM AND METHODS”, filed Oct. 21, 2003; (2) U.S. patent application Ser. No. 10/691,377 entitled “METHOD AND APPARATUS FOR CONVERTING FROM SOURCE COLOR SPACE TO RGBW TARGET COLOR SPACE”, filed Oct. 21, 2003; (3) U.S. patent application Ser. No. 10/691,396 entitled “METHOD AND APPARATUS FOR CONVERTING FROM A SOURCE COLOR SPACE TO A TARGET COLOR SPACE”, filed Oct. 21, 2003; and (4) U.S. patent application Ser. No. 10/690,716 entitled “GAMUT CONVERSION SYSTEM AND METHODS” which are all hereby incorporated herein by reference in their entirety. Additional advantages have been described in (1) U.S. patent application Ser. No. 10/696,235 entitled “DISPLAY SYSTEM HAVING IMPROVED MULTIPLE MODES FOR DISPLAYING IMAGE DATA FROM MULTIPLE INPUT SOURCE FORMATS”, filed Oct. 28, 2003 and (2) U.S. patent application Ser. No. 10/696,026 entitled “SYSTEM AND METHOD FOR PERFORMING IMAGE RECONSTRUCTION AND SUBPIXEL RENDERING TO EFFECT SCALING FOR MULTI-MODE DISPLAY” filed Oct. 28, 2003; which are all hereby incorporated by reference. All patent applications mentioned in this specification are hereby incorporated by reference in their entirety. | <SOH> BRIEF DESCRIPTION OF THE DRAWINGS <EOH>The accompanying drawings, which are incorporated in, and constitute a part of this specification illustrate exemplary implementations and embodiments of the invention and, together with the description, serve to explain principles of the invention. FIG. 1 is an example of a display comprising a subpixel repeating unit wherein there are at least two subpixels comprising different sizes and/or dimensions and an associated TFT backplane. FIG. 2 is one example of a display comprising at least two subpixels having different sizes/dimensions with a TFT backplane as made in accordance with the principles of the present invention. FIG. 3 is one example of an implementation of a TFT backplane as made in accordance with the principles of the present invention. FIG. 4 is another example of an implementation of a TFT backplane as made in accordance with the principles of the present invention. detailed-description description="Detailed Description" end="lead"? | 20040323 | 20070911 | 20050929 | 68595.0 | 0 | LAO, LUNYI | TRANSISTOR BACKPLANES FOR LIQUID CRYSTAL DISPLAYS COMPRISING DIFFERENT SIZED SUBPIXELS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,731 | ACCEPTED | Apparatus, method and system for a tunneling client access point | The disclosure details the implementation of a tunneling client access point (TCAP) that is a highly secure, portable, power efficient storage and data processing mechanism. The TCAP “tunnels” data through an access terminal's (AT) input/output facilities. In one embodiment, the TCAP has no user input or output peripherals. The TCAP connects to an access terminal and a user employs the AT's user input peripherals for input, and views the TCAPs activities on the AT's display. This enables the user to observe data stored on the TCAP without it being resident on the AT, which can be useful to maintain higher levels of data security. Also, the TCAP may tunnel data through an AT across a communications network to access remote servers. The disclosure teaches how to allow users to employ traditional large user interfaces that users are already comfortable with. The disclosure, also, teaches a plug-n-play virtual private network (VPN). | 1. A portable tunneling storage and processing apparatus, comprising: a memory, wherein the memory contains a unique apparatus identifier, wherein the memory contains user verifying information; a processor disposed in communication with the memory, and configured to issue a plurality of processing instructions stored in the memory, wherein the processing instructions issue signals to: provide a terminal access to the memory; execute processing instructions from the memory on the terminal to access the terminal, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and wherein the terminal acts as a network interface proxy; process processing instructions, wherein the processing instructions are stored in the memory, wherein the processing instructions are used to issue signals to process processing instruction on the processor; encrypt the memory based on the apparatus identifier and user verifying information; effect the display of processing activity on the terminal; a conduit for external communications disposed in communication with the processor, configured to issue a plurality of communication instructions as provided by the processor, configured to issue the communication instructions as signals to engage in communications with other devices having compatible conduits, and configured to receive signals issued from the compatible conduits, wherein the conduits are USB conduits, wherein the communication instructions issue signals to: communicate with a terminal; communicate with a server; wherein the communication instruction issued signals are encrypted, wherein the encryption occurs on the processor, wherein received encrypted instruction signals are decrypted, and wherein decryption occurs on the processor. 2. A portable tunneling storage and processing apparatus, comprising: a memory, wherein the memory contains a unique apparatus identifier; a processor disposed in communication with the memory, and configured to issue a plurality of processing instructions stored in the memory, wherein the processing instructions issue signals to: provide a terminal access to the memory, process processing instructions, a conduit for external communications disposed in communication with the processor, configured to issue a plurality of communication instructions as provided by the processor, configured to issue the communication instructions as signals to engage in communications with other devices having compatible conduits, and configured to receive signals issued from the compatible conduits, wherein the communication instructions issue signals to: communicate at a terminal. 3. The apparatus of claim 2, wherein the unique apparatus identifier is a digital signature. 4. The apparatus of claim 2, wherein the memory contains user verifying information. 5. The apparatus of claim 4, wherein the user verifying information is a digital signature. 6. The apparatus of claim 4, wherein the user verifying information is a username and password. 7. The apparatus of claim 6, further, comprising: wherein the processing instructions issue signals to: encrypt the memory based on the unique apparatus identifier and user verifying information. 8. The apparatus of claim 2, further, comprising: wherein the processing instructions issue signals to: execute processing instructions from the memory on the terminal to access the terminal. 9. The apparatus of claim 2, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and acts as a network interface proxy. 10. The apparatus of claim 2, wherein the processing instructions are stored on the memory. 11. The apparatus of claim 2, wherein the processing instructions are obtained from a server. 12. The apparatus of claim 2, wherein the processing instructions are processed on the processor. 13. The apparatus of claim 12, wherein the processing instructions are processed on the processor to process files for printing. 14. The apparatus of claim 2, wherein the processing instructions are processed on the terminal. 15. The apparatus of claim 2, wherein the processing instructions are processed on the server. 16. The apparatus of claim 2, further, comprising: wherein the processing instructions issue signals to: effect the display of processing activity. 17. The apparatus of claim 16, wherein the display of processing activity occurs on the terminal. 18. The apparatus of claim 16, wherein the display of processing activity occurs directly in the terminal's video memory. 19. The apparatus of claim 2, wherein the conduits are USB conduits. 20. The apparatus of claim 2, wherein the conduits are wireless conduits. 21. The apparatus of claim 20, wherein the wireless conduits are Bluetooth. 22. The apparatus of claim 20, wherein the wireless conduits are WiFi. 23. The apparatus of claim 2, further, comprising: wherein the communication instructions issue signals to: communicate with a server. 24. The apparatus of claim 23, wherein the communication instruction issued signals are encrypted. 25. The apparatus of claim 24, wherein the encryption occurs on the processor. 26. The apparatus of claim 24, wherein the encryption occurs on the terminal. 27. The apparatus of claim 24, wherein the encryption occurs on the server. 28. The apparatus of claim 23, wherein received encrypted instruction signals are decrypted. 29. The apparatus of claim 28, wherein the encryption occurs on the processor. 30. The apparatus of claim 28, wherein the encryption occurs on the terminal. 31. The apparatus of claim 28, wherein the encryption occurs on the server. 32. A method of accessing data, comprising: engaging a portable storage device with a terminal, wherein the portable storage device has a processor, wherein the portable storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor, wherein the conduits are USB conduits; providing the memory for access on the terminal, wherein the memory is mounted on the terminal; executing processing instructions from the memory on the terminal to access the terminal; communicating through the conduit at a terminal, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and acts as a network interface proxy, wherein communication instruction issued signals are encrypted, wherein the encryption occurs on the processor, wherein received encrypted instruction signals are decrypted, wherein decryption occurs on the processor; executing processing instructions on the processor, wherein the processing instructions are stored on the memory, wherein the processing instructions are used to issue signals to process processing instruction on the processor; and effecting the display of processing activity on the terminal. 33. A method of accessing data, comprising: disposing a portable storage device in communication with a terminal, wherein the portable storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor; providing the memory for access on the terminal; executing processing instructions from the memory on the terminal to access the. terminal; communicating through the conduit; processing processing instructions. 34. The method of claim 33, wherein the conduits are USB conduits. 35. The method of claim 33, wherein the conduits are wireless conduits. 36. The method of claim 35, wherein the wireless conduits are Bluetooth. 37. The method of claim 35, wherein the wireless conduits are WiFi. 38. The method of claim 33, wherein the memory is mounted at the terminal. 39. The method of claim 33, wherein the communication through the conduit is at the terminal. 40. The method of claim 39, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices. 41. The method of claim 39, wherein the terminal acts as a network interface proxy. 42. The method of claim 33, wherein a communications through the conduit are encrypted. 43. The method of claim 42, wherein the encryption occurs on the processor. 44. The method of claim 43, wherein the encryption occurs on the processor by executing communication instructions from memory. 45. The method of claim 42, wherein the encryption occurs on the terminal. 46. The method of claim 42, wherein the encryption occurs on the server. 47. The method of claim 33, wherein received encrypted instruction signals are decrypted. 48. The method of claim 47, wherein the decryption occurs on the processor. 49. The method of claim 48, wherein the decryption occurs on the processor by executing communication instructions from memory. 50. The method of claim 47, wherein the decryption occurs on the terminal. 51. The method of claim 47, wherein the decryption occurs on the server. 52. The method of claim 33, wherein the processing instructions are stored in the memory. 53. The method of claim 33, wherein the processing of processing instructions occurs on the processor. 54. The method of claim 33, wherein the processing of processing instructions occurs on the terminal. 55. The method of claim 33, wherein the processing of processing instructions occurs on the server. 56. The method of claim 33, wherein the processing instructions are used to issue signals to process processing instruction on the processor. 57. The method of claim 55, wherein the processing instructions are used to issue signals to process processing instruction on the processor to process files for printing. 58. The method of claim 33, further, comprising: effecting the display of processing activity. 59. The method of claim 58, wherein the display occurs on the terminal. 60. The method of claim 59 wherein the display occurs on the terminal by writing directly into video memory. 61. A system to access data, comprising: means to engage a portable storage device with a terminal, wherein the portable storage device has a processor, wherein the portable storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor, wherein the conduits are USB conduits; means to provide the memory for access on the terminal, wherein the memory is mounted on the terminal; means to execute processing instructions from the memory on the terminal to access the terminal; means to communicate through the conduit at a terminal, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and acts as a network interface proxy, wherein communication instruction issued signals are encrypted, wherein the encryption occurs on the processor, wherein received encrypted instruction signals are decrypted, wherein decryption occurs on the processor; means to execute processing instructions on the processor, wherein the processing instructions are stored on the memory, wherein the processing instructions are used to issue signals to process processing instruction on the processor; and means to effect the display of processing activity on the terminal. 62. A system to access data, comprising: means to dispose a portable storage device in communication with a terminal, wherein the portable storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor; means to provide the memory for access on the terminal; means to execute processing instructions from the memory on the terminal to access the terminal; means to communicate through the conduit; means to process processing instructions. 63. A medium readable by a processor to access data, comprising: instruction signals in the processor readable medium, wherein the instruction signals are issuable by the processor to: engage a portable storage device with a terminal, wherein the portable storage device has a processor, wherein the portable storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor, wherein the conduits are USB conduits; provide the memory for access on the terminal, wherein the memory is mounted on the terminal; execute processing instructions from the memory on the terminal to access the terminal; communicate through the conduit at a terminal, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and acts as a network interface proxy, wherein communication instruction issued signals are encrypted, wherein the encryption occurs on the processor, wherein received encrypted instruction signals are decrypted, wherein decryption occurs on the processor; execute processing instructions on the processor, wherein the processing instructions are stored on the memory, wherein the processing instructions are used to issue signals to process processing instruction on the processor; and means to effect the display of processing activity on the terminal. 64. A medium readable by a processor to access data, comprising: instruction signals in the processor readable medium, wherein the instruction signals are issuable by the processor to: dispose a portable storage device in communication with a terminal, wherein the portable storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor; provide the memory for access on the terminal; execute processing instructions from the memory on the terminal to access the terminal; communicate through the conduit; process processing instructions. 65. An apparatus to access data, comprising: a memory; a processor disposed in communication with said memory, and configured to issue a plurality of processing instructions stored in the memory, wherein the instructions issue signals to: engage a portable storage device with a terminal, wherein the portable storage device has a processor, wherein the portable storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor, wherein the conduits are USB conduits; provide-the memory for access on the terminal, wherein the memory is mounted on the terminal; execute processing instructions from the memory on the terminal to access the terminal; communicate through the conduit at a terminal, wherein the terminal acts as a proxy for the terminal's input and output peripheral devices, and acts as a network interface proxy, wherein communication instruction issued signals are encrypted, wherein the encryption occurs on the processor, wherein received encrypted instruction signals are decrypted, wherein decryption occurs on the processor; execute processing instructions on the processor, wherein the processing instructions are stored on the memory, wherein the processing instructions are used to issue signals to process processing instruction on the processor; and means to effect the display of processing activity on the terminal. 66. An apparatus to access data, comprising: a memory; a processor disposed in communication with said memory, and configured to issue a plurality of processing instructions stored in the memory, wherein the instructions issue signals to: dispose a portable storage device in communication with a terminal, wherein the portable storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor; provide the memory for access on the terminal; execute processing instructions from the memory on the terminal to access the terminal; communicate through the conduit; process processing instructions. 67. A method of accessing data, comprising: receiving requests from a terminal, wherein a portable storage device is disposed in communication with the terminal, wherein the storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory, wherein the memory and a storage conduit are disposed in communication with the processor, wherein the storage device is responsible for generating the received requests; providing responses to the storage device's requests. 68. A method of accessing data, comprising: disposing a portable storage device in communication with a-terminal, wherein the storage device has a processor, wherein the storage device connects to the terminal across compatible conduits for external communications, wherein the storage device has a memory; employing the terminal for input/output (I/O) control for the portable storage device; executing instructions on the portable storage device; and displaying results of execution on the terminal. 69. The method of claim 68, further, comprising: storing the results of execution on the terminal in the portable storage device's memory. | FIELD The present invention is directed generally to an apparatus, method, and system of accessing data, and more particularly, to an apparatus, method and system to execute and process data by tunneling access through a terminal. BACKGROUND Portable Computing and Storage Computing devices have been becoming smaller over time. Currently, some of the smallest computing devices are in the form of personal digital assistants (PDAs). Such devices usually come with a touch screen, an input stylus and/or mini keyboard, and battery source. These devices, typically, have storage capacities around 64 MB. Examples of these devices include Palm's Palm Pilot. Information Technology Systems Typically, users, which may be people and/or other systems, engage information technology systems (e.g., commonly computers) to facilitate information processing. In turn, computers employ processors to process information; such processors are often referred to as central processing units (CPU). A common form of processor is referred to as a microprocessor. A computer operating system, which, typically, is software executed by CPU on a computer, enables and facilitates users to access and operate computer information technology and resources. Common resources employed in information technology systems include: input and output mechanisms through which data may pass into and out of a computer; memory storage into which data may be saved; and processors by which information may be processed. Often information technology systems are used to collect data for later retrieval, analysis, and manipulation, commonly, which is facilitated through database software. Information technology systems provide interfaces that allow users to access and operate various system components. User Interface The function of computer interfaces in some respects is similar to automobile operation interfaces. Automobile operation interface elements such as steering wheels, gearshifts, and speedometers facilitate the access, operation, and display of automobile resources, functionality, and status. Computer interaction interface elements such as check boxes, cursors, menus, scrollers, and windows (collectively and commonly referred to as widgets) similarly facilitate the access, operation, and display of data and computer hardware and operating system resources, functionality, and status. Operation interfaces are commonly called user interfaces. Graphical user interfaces (GUIs) such as the Apple Macintosh Operating System's Aqua, Microsoft's Windows XP, or Unix's X-Windows provide a baseline and means of accessing and displaying information, graphically, to users. Networks Networks are commonly thought to comprise of the interconnection and interoperation of clients, servers, and intermediary nodes in a graph topology. It should be noted that the term “server” as used herein refers generally to a computer, other device, software, or combination thereof that processes and responds to the requests of remote users across a communications network. Servers serve their information to requesting “clients.” The term “client” as used herein refers generally to a computer, other device, software, or combination thereof that is capable of processing and making requests and obtaining and processing any responses from servers across a communications network. A computer, other device, software, or combination thereof that facilitates, processes information and requests, and/or furthers the passage of information from a source user to a destination user is commonly referred to as a “node.” Networks are generally thought to facilitate the transfer of information from source points to destinations. A node specifically tasked with furthering the passage of information from a source to a destination is commonly called a “router.” There. are many forms of networks such as Local Area Networks (LANs), Pico networks, Wide Area Networks (WANs), Wireless Networks (WLANs), etc. For example, the Internet is generally accepted as being an interconnection of a multitude of networks whereby remote clients and servers may access and interoperate with one another. SUMMARY Although all of the aforementioned portable computing systems exist, no effective solution to securely access, execute, and process data is available in an extremely compact form. Currently, PDAs, which are considered among the smallest portable computing solution, are bulky, provide uncomfortably small user interfaces, and require too much power to maintain their data. Current PDA designs are complicated and cost a lot because they require great processing resources to provide custom user interfaces and operating systems. Further, current PDAs are generally limited in the amount of data they can store or access. No solution exists that allows users to employ traditional large user interfaces they are already comfortable with, provides greater portability, provides greater memory footprints, draws less power, and provides security for data on the device. As such, the disclosed tunneling client access point (TCAP) is very easy to use; at most it requires the user to simply plug the device into any existing and available desktop or laptop computer, through which, the TCAP can make use of a traditional user interface and input/output (I/O) peripherals, while the TCAP itself, otherwise, provides storage, execution, and/or processing resources. Thus, the TCAP requires no power source to maintain its data and allows for a highly portable “thumb” footprint. Also, by providing the equivalent of a plug-n-play virtual private network (VPN), the TCAP provides certain kinds of accessing of remote data in an easy and secure manner that was unavailable in the prior art. In accordance with certain aspects of the disclosure, the above-identified problems of limited computing devices are overcome and a technical advance is achieved in the art of portable computing and data access. An exemplary tunneling client access point (TCAP) includes a method to dispose a portable storage device in communication with a terminal. The method includes providing the memory for access on the terminal, executing processing instructions from the memory on the terminal to access the terminal, communicating through a conduit, and processing the processing instructions. In accordance with another embodiment, a portable tunneling storage processor is disclosed. The apparatus has a memory and a processor disposed in communication with the memory, and configured to issue a plurality of processing instructions stored in the memory. Also, the apparatus has a conduit for external communications disposed in communication with the processor, configured to issue a plurality of communication instructions as provided by the processor, configured to issue the communication instructions as signals to engage in communications with other devices having compatible conduits, and configured to receive signals issued from the compatible conduits. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate various non-limiting, example, inventive aspects in accordance with the present disclosure: FIG. 1 is of a flow diagram illustrating embodiments of a tunneling client access point (TCAP); FIG. 2 is of a flow diagram illustrating embodiments of a system of tunneling client access point and access terminal interaction; FIG. 3 is of a flow diagram illustrating embodiments of engaging the tunneling client access point to an access terminal interaction; FIG. 4 is of a flow diagram illustrating embodiments of accessing the tunneling client access point and server through an access terminal; FIGS. 5-8 is of a flow diagram illustrating embodiments of facilities, programs, and/or services that the tunneling client access point and server may provide to the user as accessed through an access terminal; FIG. 9 is of a block diagram illustrating embodiments of a tunneling client access point server controller; FIG. 10 is of a block diagram illustrating embodiments of a tunneling client access point controller; The leading number of each reference number within the drawings indicates the first figure in which that reference number is introduced. As such, reference number 101 is first introduced in FIG. 1. Reference number 201 is first introduced in FIG. 2, etc. DETAILED DESCRIPTION Topology FIG. 1 illustrates embodiments for a topology between a tunneling client access point (TCAP) (see FIG. 10 for more details on the TCAP) and TCAP server (TCAPS) (see FIG. 9 for more details on the TCAPS). In this embodiment, a user 133a may plug-in a TCAP into any number of access terminals 127 located anywhere. Access terminals (ATs) may be any number of computing devices such as servers, workstations, desktop computers, laptops, portable digital assistants (PDAs), and/or the like. The type of AT used is not important other than the device should provide a compatible mechanism of engagement to the TCAP 130 and provide an operating environment for the user to engage the TCAP through the AT. In one embodiment, the TCAP provides a universal serial bus (USB) connector through which it may plug into an AT. In other embodiment, the TCAP may employ Bluetooth, WiFi and/or other wireless connectivity protocols to connect with ATs that are also so equipped. In one embodiment, the AT provides Java and/or Windows runtime environments, which allows the TCAP to interact with the input/output mechanisms of the AT. See FIG. 9 for more details and embodiments on the types of connections that may be employed by the TCAP. Once the TCAP has engaged with an AT, it can provide the user with access to its storage and processing facilities. If the AT is connected to a communication network 113, the TCAP may then communicate beyond the AT. In one embodiment, the TCAP can provide extended storage and/or processing resources by engaging servers 110, 115, 120, which have access to and can provide extended storage 105 to the TCAP through the AT. In one embodiment, a single server and storage device may provide such TCAP server support. In another embodiment, server support is provided over a communications network, e.g., the Internet, by an array of front-end load-balancing servers 120. These servers can provide access to storage facilities within the servers or to remote storage 105 across a communications network 113b, c (e.g., a local area network (LAN)). In such an embodiment, a backend server 110 may offload the front-end server with regard to data access to provide greater throughput. For purposes of load balancing and/or redundancy, a backup server 115 may be similarly situated to provide for access and backup in an efficient manner. In such an embodiment, the back-end servers may be connected to the front-end servers through a communications network 113b (e.g., wide area network (WAN)). The backend servers 110, 115 may be connected to the remote storage 105 through a communications network 113c as well (e.g., a high speed LAN, fiber-channel, and/or the like). Thus, to the user 133a, the contents of the TCAP 130 appear on the AT as being contained on the TCAP 125 even though much of the contents may actually reside on the servers 115, 120 and/or the servers' storage facilities 105. In these ways, the TCAP “tunnels” data through an AT. The data may be provided through the AT's I/O for the user to observe without it actually residing on the AT. Also, the TCAP may tunnel data through an AT across a communications network to access remote servers without requiring its own more complicated set of peripherals and I/O. TCAP and at Interaction FIG. 2 illustrates embodiments for a system of tunneling client access point (TCAP) (see FIG. 10 for more details on the TCAP) and access terminal interaction. FIG. 2 provides an overview for TCAP and AT interaction and subsequent figures will provide greater detail on elements of the interaction. In this embodiment, a user engages the TCAP 201. For example, the user may plug the TCAP into an AT via the AT's USB port. Thereafter the user is presented with a login prompt 205 on the AT's display mechanism, e.g., on a video monitor. After a user successfully logs in (for example by providing a user name and password) 204, the TCAP can then accept user inputs from the AT and its peripherals (the TCAP can then also provide output to the user via the AT's peripherals). The user may employ the AT's input peripherals as user input devices that control actions on the TCAP. Depending on the user's actions 215, the TCAP can be used by the AT as a storage device from which it can access and store data and programs 225. For example, if the user takes the action of opening a file from the TCAP's memory, e.g., by double clicking on an icon when the TCAP is mounted as a USB drive on the AT, then the AT may treat the TCAP as a memory device and retrieve information from the TCAP 225. If the user's action 215 is one that is directed at executing on the TCAP 215, then the AT will not be involved in any execution. For example, if the user drops an icon representing a graphics file onto a drag-and-drop location visually representing the TCAP, then the file may be copied to the TCAP where it will process and spool the file for sending the graphics file to be printed at a remote location. In such a case, all of the requirements to process and spool the file are handled by the TCAP's processor and the AT would only be used as a mechanism for user input and output and as a conduit through which the TCAP may send files. Regardless of if there is an action 215 to execute on the TCAP 220 or to access or store data on the TCAP 225, the AT is used to display the status of any actions 230. At any time the user may select to terminate TCAP related facilities executing either on the AT, a backend server, on the TCAP itself, and/or the like 235. In one embodiment, the user may select a quit option that is displayed on the AT's screen. In another embodiment, the user may simply disengage the TCAP from the AT by severing the connection (e.g., turning power off, physically pulling the device off the AT, turning off wireless transmissions, and/or the like). It should be noted that such abrupt severing may result in the loss of data, file corruption, etc. if the TCAP has not saved data that is on the AT or on some remote server, however, if the TCAP is employing flash like memory, its contents should remain intact. If there is no instruction signal to terminate the TCAP 235, execution will continue and the TCAP will continue to take and look for input from the user. Of course if the TCAP has been set to perform certain actions, those actions will continue to execute, and the TCAP may respond to remote servers when it is communicating with them through the AT. When the user issues a terminate signal 235, then the TCAP will shut down by saving any data to the TCAP that is in the AT's memory and then terminating any programs executing on both the AT and TCAP that were executed by and/or from the TCAP 240. If no activities are taking place on the TCAP and all the data is written back to the TCAP 240, then the TCAP may optionally unmount itself from the AT's file-system 245. At this point, if there is a TCAP I/O driver executing on the AT, that driver may be terminated as triggered by the absence of the TCAP at a mount point 250. After the TCAP is unmounted and/or the TCAP I/O driver is terminated, it is safe to disengage the TCAP from the AT. TCAP and at Interaction FIG. 3 illustrates embodiments engaging the tunneling client access point to an access terminal interaction. Examples of engaging the TCAP 301 with an AT were discussed above in FIG. 1 127, 130, 133a and FIG. 2 201. In one embodiment, the TCAP 130 is engaged with an access terminal 327, 305. As mentioned in FIG. 1, the TCAP is capable of engaging with ATs using a number of mechanisms. In one embodiment, the TCAP has a USB connector for plugging into an AT, which acts as a conduit for power and data transfer. In another embodiment, the TCAP may use Bluetooth to establish a wireless connection with a number of ATs. In another embodiment, the TCAP may employ WiFi. In yet another embodiment, the TCAP may employ multiple communications mechanisms. It should be noted, with some wireless mechanisms like Bluetooth and WiFi, simply coming into proximity with an AT that is configured for such wireless communication may result in the TCAP engaging with and establish a communications link with the AT. In one embodiment, the TCAP has a “connect” button that will allow such otherwise automatically engaging interactions take place only if the “connect” button is engaged by a user. Such an implementation may provide greater security for users (see FIG. 10 for more details on the TCAP). After being engaged 305, the TCAP will then power on. In an embodiment requiring a direct connection, e.g., USB, simply plugging the TCAP into the AT provides power. In a wireless embodiment, the TCAP may be on in a lower powered state or otherwise turned on by engaging the connect button as discussed above. In such an embodiment, the TCAP can employ various on-board power sources (see FIG. 10 for more details on the TCAP). The TCAP then may load its own operating system 315. The operating system can provide for interaction with the AT. In one embodiment, a Java runtime is executed on the TCAP, and Java applets communicate with the AT through Java APIs. In another embodiment, a driver is loaded onto the AT, and the on-TCAP Java operating system applets communicate to and through the AT via the driver running on the AT, wherein the driver provides an API through and to which messages may be sent. After engaging with the AT, the TCAP can provide its memory space to the AT 320. In one embodiment, the TCAP's memory is mapped and mounted as a virtual disk drive 125 storage 325. In this manner, the TCAP may be accessed and manipulated as a standard storage device through the AT's operating system. Further, the TCAP and in some cases the AT can determine if the AT is capable of accessing program instructions stored in the TCAP's memory 330. In one embodiment, the AT's operating system looks to auto-run a specified file from any drive as it mounts. In such an embodiment, the TCAP's primary interface may be specified in such a boot sequence. For example, under windows, an autorun.inf file can specify the opening of a program from the TCAP by the AT; e.g., OPEN=TCAP.EXE. Many operating systems are capable of at least accessing the TCAP as a USB memory drive 330 and mounting its contents as a drive, which usually becomes accessible in file browsing window 125. If the TCAP does not mount, the AT's operating system will usually generate an error informing the user of a mounting problem. If the AT is not capable of executing instruction from the TCAP, a determination is made if an appropriate driver is loaded on the AT to access the TCAP 335. In one embodiment, the TCAP can check to see if an API is running on the AT. For example, the TCAP provide an executable to be launched, e.g., as specified through autorun.inf, and can establish communications through its connection to the AT, e.g., employing TCP/IP communications over the USB port. In such an embodiment, the TCAP can ping the AT for the program, and if an acknowledgement is received, the TCAP has determined that proper drivers and APIs exist. If no such API exists, the TCAP may launch a driver installation program for the AT as through an autorun.inf. In an alternative embodiment, if nothing happens, a user may double click onto an installer program that is stored on the mounted TCAP 342, 340. It should be noted, that although the TCAP's memory space may be mounted, certain areas of the TCAP may be inaccessible until there is an authorization. For example, certain areas and content on the TCAP may be encrypted. It should be noted that any such access terminal modules that drive AT and TCAP interaction may be saved onto the TCAP by copying the module to a mounted TCAP. Nevertheless, if the AT is capable of accessing program instructions in TCAP memory 330, a TCAP driver is loaded on the AT 335, and/or the user engages a program in the TCAP memory 340, then the AT can execute program instructions from the TCAP's memory, which allows the TCAP to use the AT's I/O and allowing the user to interface with TCAP facilities 345. It should be noted that some ATs may not be able to mount the TCAP at all. In such an instance, the user may have to install the TCAP drivers by downloading them from a server on the Internet, loading them from a diskette or CD, and/or the like. Once the TCAP is engaged to the AT 301, execution may continue 398. TCAP and at Interaction FIG. 4 illustrates embodiments accessing the tunneling client access point and server through an access terminal. Upon engaging the TCAP to the AT as described in FIG. 3 301, 398, the user may then go on to access the TCAP and its services 498. It should be noted that users may access certain unprotected areas of the TCAP once it has been mounted, as described in FIG. 3. However, to more fully access the TCAP's facilities, the user may be prompted to either login and/or registration window 205a to access the TCAP and its services, which may be displayed on the AT. 405. It is important to note that in one embodiment, the execution of the login and/or registration routines are handled by the TCAP's processor. In such an embodiment, the TCAP may run a small Web server providing login facilities, and connect to other Web based services through the AT's connection to the Internet. Further, the TCAP may employ a basic Web browsing core engine by which it may connect to Web services through the AT's connection to a communications network like the Internet. For purposes of security, in one embodiment, the TCAP may connect to a remote server by employing a secure connection, e.g., HTTPS, VPN, and/or the like. Upon displaying a login window 405, e.g., 205a, the user may select to register to access the TCAP and its services, or they may simply log in by providing security verification. In one example, security authorization may be granted by simply providing a user and password as provided through a registration process. In another embodiment, authorization may be granted through biometric data. For example, the TCAP may integrate a fingerprint and/or heat sensor IC into its housing. Employing such a device, and simply by providing one's finger print by laying your finger to the TCAP's surface, would provide the login facility with authorization if the user's finger print matches one that was stored during the registration process. If the user does not attempt to login 415, i.e., if the user wishes to register to use the TCAP and its services, then the TCAP can determine if the AT is online 420. This may be accomplished in a number of ways. In one embodiment, the TCAP itself may simply ping a given server and if acknowledgement of receipt is received, the TCAP is online. In another embodiment, the TCAP can query for online status by engaging the AT through the installed APIs. If the AT is not online, then the user may be presented with an error message 425. Thus, if a user does not have a login, and does not have the ability to register, then restricted areas of the TCAP will remain unavailable. Thereafter, flow can continue 498 and the user may have another opportunity to login and/or register. In one embodiment as a login integrity check, the TCAP keeps track of the number of failed attempts to login and/or register and may lock-out all further access if a specified number of failed attempts occurs. In one embodiment, the lockdown may be permanent by erasing all data on the TCAP. In another embodiment, the TCAP will disallow further attempts for a specified period of time. If the user is attempting to register 415, and the AT is online 420, then the user map provide registration information 440 into a screen form 440a. Registration information fields may require a user's name, address, email address, credit card information, biometric information (e.g., requiring the user to touch a biometric fingerprint IC on the TCAP), and/or the like. The TCAP may determine if all the information was provided as required for registration and may query backend servers to determine if the user information is unique 445. If the user did not properly fill out the registration information or if another user is already registered, the TCAP can provided an error message to such effect. Also, both the TCAP and its back-end servers may make log entries tracking such failed attempts for purposes of defending against fraud and/or security breaches. The user may then modify the registration information 440 and again attempt to register. Similarly to the login integrity checks, the TCAP can lockout registration attempts if the user fails to register more than some specified number of times. Upon providing proper registration information 445 or proper login authentication 415, the TCAP can query backend servers to see if the user is registered. In one embodiment, such verification may be achieved by sending a query to the servers to check its database for the authorization information and/or for duplicate registrations. The servers would then respond providing an acknowledgment of proper registration and authorization to access data on the backend servers. If the users are not registered on the backend servers 430, then the TCAP can provide an error message to the user for display on the AT to such effect 435. In an alternative embodiment, the registration information may be stored on the TCAP itself. In one embodiment, the registration would be maintained in encrypted form. Thus, the user's login information may be checked relative to the information the TCAP itself, and if there is a match, access may be granted, otherwise an error message will be displayed 435. The TCAP may then continue 498 to operate as if it were just engaged to the AT. If the user is confirmed to be registered 430, then the TCAP may provide options for display 453, 453a. Depending on the context and purpose of a particular TCAP, the options may vary. For example, the a screen 453a may provide the user with the options to access data either online or offline. The user might simply click on a button and gain secure access to such data that may be decrypted by the TCAP. In one embodiment, the TCAP will determine if the AT is online 455. If this was already determined 420, this check 455 may be skipped. If the AT is online 455, optionally, the TCAP determines if the user wishes to synchronize the contents of the TCAP with storage facilities at the backend server 470. In one embodiment, the user may designate that such synchronization is to always take place. If synchronization is specified 470, then the TCAP will provide and receive updated data to and from the backend servers, overwriting older data with updated versions of the data 475. If the AT is online 455 and/or after any synchronization 475, the TCAP may provide the user with all of its service options as authorized by the account and programs available on the TCAP and at the backend server 480. Once again, these facilities, programs, and/or services may vary greatly depending on the context and deployment requirements of the user. The options to be presented to the user from the TCAP or the TCAP services from the backend server, as displayed through the TCAP onto the AT's display 480, are myriad and some example embodiments are provided in FIGS. 5-8. Upon presenting the user with the options, the user is then able to access, execute, store data and programs on the TCAP and on the remote server 485. All areas of the TCAP and services are then open, including any encrypted data areas. If the AT is not online 455, the TCAP may provide options for the user not including online services 460. In one embodiment, the online options that may be presented on the AT display will be dimmed and/or omitted to reflect the lack of accessibility. However, the user will be able to access, execute, store data and programs on the TCAP including any encrypted data areas 465. TCAP Facilities and Services FIGS. 5-8 illustrate embodiments of facilities, programs, and/or services that the tunneling client access point and server may provide to the user as accessed through an AT. Any particular set of facilities may have a myriad of options. The options and the general nature of the facilities provided on any particular TCAP are dependant upon the requirements of a given set of users. For example, certain groups and/or agencies may require TCAPS to be targeted towards consumer photographs, and may employ TCAPs to further that end. Other groups may require high security facilities, and tailor the TCAPs accordingly. In various environments, an organization may wish to provide a secure infrastructure to all of its agents for securely accessing the organization's data from anywhere and such an organization could tailor the TCAPs contents to reflect and respond to its needs. By providing a generalized infrastructure on the TCAP backend servers and within the TCAP by using a generalized processor, the TCAPs may be deployed in numerous environments. In one particular embodiment as in FIG. 5, the TCAP provides facilities to access, process, and store email, files, music, photos and videos through the TCAP. Upon engaging 101 of FIG. 1 the TCAP 130 to an AT 307, the TCAP will mount and display through the AT's file browser window 125 of FIG. 1. As has already described, in the case where the AT has no TCAP driver software, the user may double click on the installer software stored on the TCAP 507. Doing so will launch the installer software from the TCAP's memory to execute on the AT, and the user may be presented with a window to confirm the desire to install the TCAP software onto the AT 507. Upon confirming the install 507, the software will install on the AT and the user will be asked to wait as they are apprised of the install progress 509. Upon installation, the TCAP front-end software may execute and present the user with various options in various and fanciful interface formats 511, 460, 480 of FIG. 4. In one embodiment, these user interfaces and programs are Java applications that may execute on the AT and a present Java runtime. In an alternative embodiment, a small applet may run on the AT, but all other activities may execute on the TCAP's processor, which would use the AT display only as a display terminal. In the embodiment where the TCAP executes program instructions, the TCAP may be engaged to receive commands and execute by receiving a signal from the access terminal driver instructing it to execute certain program files or, alternatively, looking to default location and executing program instructions. In yet another embodiment, the TCAP may obtain updated interfaces and programs from a backend server for execution either on the TCAP itself and/or the AT; this may be done by synchronization with the backend server and checking for updates of specified files at the backend server. By engaging the user interface, perhaps by clicking on a button to open the TCAP facilities and services 511, the interface may further unfurl to present options to access said facilities and services 513. Here, the interface may reflect ownership of the TCAP by providing a welcome screen and showing some resources available to the user; for example, a button entitled “My Stuff” may serve as a mechanism to advance the user to a screen where they may access their personal data store. At this point the user may attempt to login to access their data by engaging an appropriate button, which will take them to a screen that will accept login information 519. Alternatively, the user may also register if it is their first time using the TCAP by selecting an appropriate button, which will advance the user to a registration screen 515 wherein the user may enter their name, address, credit card information, etc. Upon successfully providing registration information, the user may be prompted for response to further solicitations on a follow-up screen 517. For example, depending on the services offered for a particular TCAP, the user may be provided certain perks like 5 MB of free online storage on a backend server, free photographic prints, free email access, and/or the like 517. After the user is prompted to login 518 and successfully provides proper login information 519, or after successfully registering 515 and having responded to any solicitations 517, the user may be provided with general options 521 to access data stored on the TCAP itself 522 or in their online account 520 maintained on a backend server. For example, if the user selects the option to access their online storage 520, they may be presented with more options to interact with email, files, music, photos and videos that are available online 523. Perhaps if the user wished to check their email, the user might select to interact with their email, and a screen allowing them to navigate through their email account(s) would be presented 525. Such online access to data may be facilitated through http protocols whereby the TCAP applications send and receive data through http commands across a communications network interacting with the backend servers and/or other servers. Any received results may be parsed and imbedded in a GUI representation of a Java appliation. For example, the email facility may run as a Java applet 525 and may employ a POP mail protocol to pull data from a specified mail server to present to the user. Similarly, many other facilities may be engaged by the user through the TCAP. In one embodiment, the user may drag 508 a file 506 onto a drag-and-drop zone 505 that is presented on the TCAP interface. Upon so doing, various drag-and-drop options may unfurl and present themselves to the user 550. It should be noted that the file may come from anywhere, i.e., from the AT, the TCAP, and/or otherwise. For example, upon dragging and dropping a graphics file, a user may be prompted with options to order prints, upload the file to an online storage space, save the file to the TCAP's memory space, cancel the action, and/or the like 550. If the user sends the file for storage, or otherwise wishes to see and manage their data, an interface allowing for such management may be presented 555. The interface may organize and allow access to general data, picture, and music formats 554, provide usage statistics (e.g., free space, capacity, used space, etc.) 553, provide actions to manipulate and organize the data 552, provide status on storage usage on the TCAP 551 and online 549, and/or the like. Should the user engage a user interface element indicating the wish to manipulate their picture data 548, the TCAP interface will update to allow more specific interaction with the user's photos 557. In such a screen, the user may select various stored pictures and then indicate a desire to order photo prints by engaging the appropriate user interface element 558. Should the user indicate their desire for prints 558, they will be presented with an updated interface allowing the specification of what graphics files they wish to have printed 559. In one embodiment, the users may drag-and-drop files into a drop zone, or otherwise engage file browsing mechanisms 560 that allow for the selection of desired files. Upon having identified the files for prints 559, a user may be presented with an interface allowing for the selection of print sizes and quantities 561. After making such specifications, the user may be required to provide shipping information 563 and information for payments 565. After providing the billing information to a backend server for processing and approval, the user may be presented with a confirmation interface allowing for editing of the order, providing confirmation of costs, and allowing for submission of a final order for the selected prints 567. Upon submitting the order, the TCAP will process the files for spooling to a backend server that will accept the order and files, which will be developed as prints and the user's account will be charged accordingly. In one embodiment, all of the above order and image processing operations occur and execute on the TCAP CPU. For example, the TCAP may employ various rendering technologies, e.g., ghostscript, to allow it to read and save PDFs and other media formats. FIG. 6 goes on to illustrate embodiments and facets of the facilities of FIG. 5. The TCAP interface allows the user to perform various actions at any given moment. As has already been discussed in FIG. 5, the user may drag 508 a file 506 onto a drag and drop zone 505 so as to provide the file to the TCAP for further manipulation. As in 550 of FIG. 5, the user may be presented with various options subsequent to a drag-and-drop operation. Also, the TCAP interface may provide visual feedback that files have been dropped in the drop zone by highlighting the drop zone 505b. Should the user wish they may close the TCAP interface by engaging a close option 633. Also, the ability to change and/or update their personal information may be accessed through the TCAP interface 616, which would provide a form allowing the user to update their registration information 630. In one embodiment, should the user forget their login information, they may request login help 635 and the TCAP will send their authorization information to the last known email address and inform the user of same 640. Also, the TCAP interface may provide help facilities that may be accessed at any time by simply engaging a help facility user interface element 617. So doing will provide the user with help screen information as to how to interact with the TCAP's facilities 625. Upon providing proper login information 619 and logging-in 619, the user may be presented with a welcome screen with various options to access their data 621 as has already been discussed in FIG. 5, 521. By engaging a user interface element to access online storage 620, the user may be presented with various options to interact with online storage 623, 523 of FIG. 5. Should the user wish to interact with data on the TCAP itself, the user may indicate so by engaging the appropriate user interface option 622. So doing will provide the user with further options related to data stored on the TCAP 655. The user may engage an option to view the storage contents 658 and the TCAP interface will provide a listing of the contents 662, which may be manipulated through selection and drag-and-drop operations with the files. In one embodiment, the user may order prints of photos 657 from files that are on the TCAP itself. As discussed in FIG. 5, the user may select files for which they desire prints 660. Here, the selected files will first be processed by the TCAP in preparation for sending to backend servers and file manipulations 670. The user may specify various attributes regarding the prints they desire, e.g., the size, number, cropping, red-eye correction, visual effects, and/or the like 661. In one embodiment, such processing occurs on the TCAP processor, while in other embodiments such processing can take place on the AT or backend server. Once again, the user may provide a shipping address 663, and make a final review to place the order 667. Upon committing to the order 667, the processed files are uploaded to the backend servers that will use the files to generate prints 690. A confirmation screen may then be provided to the user with an order number and other relevant information 695. FIG. 7 goes on to illustrate embodiments and facets of the facilities of FIGS. 5-6 as may apply in different environments. As is demonstrated, the look and feel of the TCAP interface is highly malleable and can serve in many environments. FIG. 7 illustrates that even within a single organization, various environments might benefit from TCAPs and services tailored to serve such environments 733b-d. In this case TCAPs can serve in consumer 733b, industry trade 733c, corporate 733d, and/or the like environments. As has already been discussed, initially in any of the environments, after engaging the TCAP to an AT, the user may be prompted to install the TCAP interface 705 and informed of the installation procedure 710. The user may then be presented with the installed TCAP interface 715, which may be activated by engaging an interface element to unfurl the interface, e.g., in this case by opening the top to a can of soda 717. Opening the interface will present the user with various options as 720, as has already been discussed in FIGS. 5-6. Similarly the user may login 725 or make a selection to register for various TCAP services and provide the requisite information in the provided form 730. Upon registering and/or logging-in 725, various options may be presented based upon the configuration of the TCAP. For example, if the TCAP was configured and tailored for consumers, then upon logging in 725 the consumer user might be presented 733a-b with various consumer related options 740. Similarly, if the TCAP were tailored for 733a, c the trade industry or 733a, d the corporate environment, options specific to the trade industry 770 and corporate environment 760 may be presented. In one embodiment, an organization wishing to provide TCAPs to consumers might provide options 740 for free music downloads 743, free Internet radio streaming 748, free news (e.g., provided through an RSS feed from a server) 766, free photo printing 750, free email 740, free coupons 742, free online storage 741, and/or the like. Users could further engage such services (e.g., clicking free music file links for downloading to the TCAP, by ordering prints 750, etc. For example, the user may select files on the TCAP 750, select the types of photos they would like to receive 752, specify a delivery address 754, confirm the order 756 all of which will result in the TCAP processing the files and uploading them to the backend servers for generation of prints (as has already been discussed in FIGS. 5-6). In another embodiment, an organization wishing to provide TCAPs to a trade industry might provide options 770 for advertising 780, events 775, promotions 772, and/or the like. It is important to note that information regarding such options may be stored either on the TCAP or at a backend server. In one embodiment, such information may be constantly synchronized from the backend servers to the TCAPs. This would allow an organization to provide updates to the trade industry to all authorized TCAP “key holders.” In such an embodiment, the user may be presented with various advertising related materials for the organization, e.g., print, television, outdoor, radio, web, and/or the like 780. With regard to events, the user may be presented with various related materials for the organization, e.g., trade shows, music regional, sponsorship, Web, and/or the like 775. With regard to promotions, the user may be presented with various related materials for the organization, e.g., rebates, coupons, premiums, and/or the like 772. In another embodiment, an organization wishing to provide TCAPs to those in the corporate environment and might provide options relating to various corporate entities 760. Selecting any of the corporate entities 760 may provide the user with options to view various reports, presentations, and/or the like, e.g., annual reports, 10K reports, and/or the like 765. Similarly, the reports may reside on the TCAP and/or the corporate TCAP can act as a security key allowing the user to see the latest corporate related materials from a remote backend server. FIG. 8 goes on to illustrate embodiments and facets of the facilities of FIGS. 5-7 as may apply in different environments. FIG. 8 illustrates that TCAPs may serve to provide-heightened security to any environment. As has been discussed in previous figures, users may engage the TCAP interface 805 to access various options 810. The TCAP interface is highly adaptable and various services may be presented within it. For example, a stock ticker may be provided as part of the interface in a financial setting 810. Any number of live data feeds may dynamically update on the face of the interface. Upon logging-in 815 or registering a new account 820, the user may be informed that communications that are taking place are secured 825. In one embodiment, various encryption formats may be used by the TCAP to send information securely to the backend servers. It is important to note that in such an embodiment, even if data moving out of the TCAP and across the AT were captured at the AT, such data would not be readable because the data was encrypted by the TCAP's processor. As such, the TCAP acts as a “key” and provides a plug-and-play VPN to users. Such functionality, heretofore, has been very difficult to set up and/or maintain. In this way, all communications, options presented and views of user data are made available only to the TCAP with the proper decryption key. In heightened security environments, display of TCAP data is provided on the screen only in bitmapped format straight to the video memory of the AT and, therefore, is not stored anywhere else on the AT. This decreases the likelihood of capturing sensitive data. As such, the user may access their data on the TCAP and/or online 830 in a secure form whereby the user may navigate and interact with his/her data and various services 835 in a secure manner. Tunneling Client Access Point Server Controller FIG. 9 illustrates one embodiment incorporated into a tunneling client access point server (TCAPS) controller 901. In this embodiment, the TCAP controller 901 may serve to process, store, search, serve, identify, instruct, generate, match and/or update data in conjunction with a TCAP (see FIG. 10 for more details on the TCAP). TCAPS act as backend servers to TCAPs, wherein TCAPS provide storage and/or processing resources to great and/or complex for the TCAP to service itself. In effect, the TCAPS transparently extend the capacity of a TCAP. In one embodiment, the TCAPS controller 901 may be connected to and/or communicate with entities such as, but not limited to: one or more users from user input devices 911; peripheral devices 912; and/or a communications network 913. The TCAPS controller may even be connected to and/or communicate with a cryptographic processor device 928. A TCAPS controller 901 may be based on common computer systems that may comprise, but are not limited to, components such as: a computer systemization 902 connected to memory 929. Computer Systemization A computer systemization 902 may comprise a clock 930, central processing unit (CPU) 903, a read only memory (ROM) 906, a random access memory (RAM) 905, and/or an interface bus 907, and most frequently, although not necessarily, are all interconnected and/or communicating through a system bus 904. Optionally, a cryptographic processor 926 may be connected to the system bus. The system clock typically has a crystal oscillator and provides a base signal. The clock is typically coupled to the system bus and various clock multipliers that will increase or decrease the base operating frequency for other components interconnected in the computer systemization. The clock and various components in a computer systemization drive signals embodying information throughout the system. Such transmission and reception of signals embodying information throughout a computer systemization may be commonly referred to as communications. These communicative signals may further be transmitted, received, and the cause of return and/or reply signal communications beyond the instant computer systemization to: communications networks, input devices, other computer systemizations, peripheral devices, and/or the like. Of course, any of the above components may be connected directly to one another, connected to the CPU, and/or organized in numerous variations employed as exemplified by various computer systems. The CPU comprises at least one high-speed data processor adequate to execute program modules for executing user and/or system-generated requests. The CPU may be a microprocessor such as AMD's Athlon, Duron and/or Opteron; IBM and/or Motorola's PowerPC; Intel's Celeron, Itanium, Pentium and/or Xeon; and/or the like processor(s). The CPU interacts with memory through signal passing through conductive conduits to execute stored program code according to conventional data processing techniques. Such signal passing facilitates communication within the TCAPS controller and beyond through various interfaces. Should processing requirements dictate a greater amount speed, mainframe and super computer architectures may similarly be employed. Interface Adapters Interface bus(ses) 907 may accept, connect, and/or communicate to a number of interface adapters, conventionally although not necessarily in the form of adapter cards, such as but not limited to: input output interfaces (I/O) 908, storage interfaces 909, network interfaces 910, and/or the like. Optionally, cryptographic processor interfaces 927 similarly may be connected to the interface bus. The interface bus provides for the communications of interface adapters with one another as well as with other components of the computer systemization. Interface adapters are adapted for a compatible interface bus. Interface adapters conventionally connect to the interface bus via a slot architecture. Conventional slot architectures may be employed, such as, but not limited to: Accelerated Graphics Port (AGP), Card Bus, (Extended) Industry Standard Architecture ((E)ISA), Micro Channel Architecture (MCA), NuBus, Peripheral Component Interconnect (Extended) (PCI(X)), Personal Computer Memory Card International Association (PCMCIA), and/or the like. Storage interfaces 909 may accept, communicate, and/or connect to a number of storage devices such as, but not limited to: storage devices 914, removable disc devices, and/or the like. Storage interfaces may employ connection protocols such as, but not limited to: (Ultra) (Serial) Advanced Technology Attachment (Packet Interface) ((Ultra) (Serial) ATA(PI)), (Enhanced) Integrated Drive Electronics ((E)IDE), Institute of Electrical and Electronics Engineers (IEEE) 1394, fiber channel, Small Computer Systems Interface (SCSI), Universal Serial Bus (USB), and/or the like. Network interfaces 910 may accept, communicate, and/or connect to a communications network 913. Network interfaces may employ connection protocols such as, but not limited to: direct connect, Ethernet (thick, thin, twisted pair 10/100/1000 Base T, and/or the like), Token Ring, wireless connection such as IEEE 802.11a-x, and/or the like. A communications network may be any one and/or the combination of the following: a direct interconnection; the Internet; a Local Area Network (LAN); a Metropolitan Area Network (MAN); an Operating Missions as Nodes on the Internet (OMNI); a secured custom connection; a Wide Area Network (WAN); a wireless network (e.g., employing protocols such as, but not limited to a Wireless Application Protocol (WAP), I-mode, and/or the like); and/or the like. A network interface may be regarded as a specialized form of an input output interface. Further, multiple network interfaces 910 may be used to engage with various communications network types 913. For example, multiple network interfaces may be employed to allow for the communication over broadcast, multicast, and/or unicast networks. Input Output interfaces (I/O) 908 may accept, communicate, and/or connect to user input devices 911, peripheral devices 912, cryptographic processor devices 928, and/or the like. I/O may employ connection protocols such as, but not limited to: Apple Desktop Bus (ADB); Apple Desktop Connector (ADC); audio: analog, digital, monaural, RCA, stereo, and/or the like; IEEE 1394a-b; infrared; joystick; keyboard; midi; optical; PC AT; PS/2; parallel; radio; serial; USB; video interface: BNC, composite, digital, Digital Visual Interface (DVI), RCA, S-Video, VGA, and/or the like; wireless; and/or the like. A common output device is a video display, which typically comprises a Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD) based monitor with an interface (e.g., DVI circuitry and cable) that accepts signals from a video interface. The video interface composites information generated by a computer systemization and generates video signals based on the composited information in a video memory frame. Typically, the video interface provides the composited video information through a video connection interface that accepts a video display interface (e.g., a DVI connector accepting a DVI display cable). User input devices 911 may be card readers, dongles, finger print readers, gloves, graphics tablets, joysticks, keyboards, mouse (mice), trackballs, trackpads, retina readers, and/or the like. Peripheral devices 912 may be connected and/or communicate to I/O and/or other facilities of the like such as network interfaces, storage interfaces, and/or the like. Peripheral devices may be audio devices, cameras, dongles (e.g., for copy protection, ensuring secure transactions with a digital signature, and/or the like), external processors (for added functionality), goggles, microphones, monitors, network interfaces, printers, scanners, storage devices, video devices, visors, and/or the like. It should be noted that although user input devices and peripheral devices may be employed, the TCAPS controller may be embodied as an embedded, dedicated, and/or headless device, wherein access would be provided over a network interface connection. Cryptographic units such as, but not limited to, microcontrollers, processors 926, interfaces 927, and/or devices 928 may be attached, and/or communicate with the TCAPS controller. A MC68HC16 microcontroller, commonly manufactured by Motorola Inc., may be used for and/or within cryptographic units. Equivalent microcontrollers and/or processors may also be used. The MC68HC16 microcontroller utilizes a 16-bit multiply-and-accumulate instruction in the 16 MHz configuration and requires less than one second to perform a 512-bit RSA private key operation. Cryptographic units support the authentication of communications from interacting agents, as well as allowing for anonymous transactions. Cryptographic units may also be configured as part of CPU. Other commercially available specialized cryptographic processors include VLSI Technology's 33 MHz 6868 or Semaphore Communications' 40 MHz Roadrunner 184. Memory Generally, any mechanization and/or embodiment allowing a processor to affect the storage and/or retrieval of information is regarded as memory 929. However, memory is a fungible technology and resource, thus, any number of memory embodiments may be employed in lieu of or in concert with one another. It is to be understood that a TCAPS controller and/or a computer systemization may employ various forms of memory 929. For example, a computer systemization may be configured wherein the functionality of on-chip CPU memory (e.g., registers), RAM, ROM, and any other storage devices are provided by a paper punch tape or paper punch card mechanism; of course such an embodiment would result in an extremely slow rate of operation. In a typical configuration, memory 929 will include ROM 906, RAM 905, and a storage device 914. A storage device 914 may be any conventional computer system storage. Storage devices may include a drum; a (fixed and/or removable) magnetic disk drive; a magneto-optical drive; an optical drive (i.e., CD ROM/RAM/Recordable (R), ReWritable (RW), DVD R/RW, etc.); and/or other devices of the like. Thus, a computer systemization generally requires and makes use of memory. Module Collection The memory 929 may contain a collection of program and/or database modules and/or data such as, but not limited to: operating system module(s) 915 (operating system); information server module(s) 916 (information server); user interface module(s) 917 (user interface); Web browser module(s) 918 (Web browser); database(s) 919; cryptographic server module(s) 920 (cryptographic server); TCAPS module(s) 935; and/or the like (i.e., collectively a module collection). These modules may be stored and accessed from the storage devices and/or from storage devices accessible through an interface bus. Although non-conventional software modules such as those in the module collection, typically, are stored in a local storage device 914, they may also be loaded and/or stored in memory such as: peripheral devices, RAM, remote storage facilities through a communications network, ROM, various forms of memory, and/or the like. Operating System The operating system module 915 is executable program code facilitating the operation of a TCAPS controller. Typically, the operating system facilitates access of I/O, network interfaces, peripheral devices, storage devices, and/or the like. The operating system may be a highly fault tolerant, scalable, and secure system such as Apple Macintosh OS X (Server), AT&T Plan 9, Be OS, Linux, Unix, and/or the like operating systems. However, more limited and/or less secure operating systems also may be employed such as Apple Macintosh OS, Microsoft DOS, Palm OS, Windows 2000/2003/3.1/95/98/CE/Millenium/NT/XP (Server), and/or the like. An operating system may communicate to and/or with other modules in a module collection, including itself, and/or the like. Most frequently, the operating system communicates with other program modules, user interfaces, and/or the like. For example, the operating system may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. The operating system, once executed by the CPU, may enable the interaction with communications networks, data, I/O, peripheral devices, program modules, memory, user input devices, and/or the like. The operating system may provide communications protocols that allow the TCAPS controller to communicate with other entities through a communications network 913. Various communication protocols may be used by the TCAPS controller as a subcarrier transport mechanism for interaction, such as, but not limited to: multicast, TCP/IP, UDP, unicast, and/or the like. Information Server An information server module 916 is stored program code that is executed by the CPU. The information server may be a conventional Internet information server such as, but not limited to Apache Software Foundation's Apache, Microsoft's Internet Information Server, and/or the. The information server may allow for the execution of program modules through facilities such as Active Server Page (ASP), ActiveX, (ANSI) (Objective-) C (++), Common Gateway Interface (CGI) scripts, Java, JavaScript, Practical Extraction Report Language (PERL), Python, WebObjects, and/or the like. The information server may support secure communications protocols such as, but not limited to, File Transfer Protocol (FTP); HyperText Transfer Protocol (HTTP); Secure Hypertext Transfer Protocol (HTTPS), Secure Socket Layer (SSL), and/or the like. The information server provides results in the form of Web pages to Web browsers, and allows for the manipulated generation of the Web pages through interaction with other program modules. After a Domain Name System (DNS) resolution portion of an HTTP request is resolved to a particular information server, the information server resolves requests for information at specified locations on a TCAPS controller based on the remainder of the HTTP request. For example, a request such as http://123.124.125.126/myInformation.html might have the IP portion of the request “123.124.125.126” resolved by a DNS server to an information server at that IP address; that information server might in turn further parse the http request for the “/myInformation.html” portion of the request and resolve it to a location in memory containing the information “myInformation.html.” Additionally, other information serving protocols may be employed across various ports, e.g., FTP communications across port 21, and/or the like. An information server may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the information server communicates with the TCAPS database 919, operating systems, other program modules, user interfaces, Web browsers, and/or the like. Access to TCAPS database may be achieved through a number of database bridge mechanisms such as through scripting languages as enumerated below (e.g., CGI) and through inter-application communication channels as enumerated below (e.g., CORBA, WebObjects, etc.). Any data requests through a Web browser are parsed through the bridge mechanism into appropriate grammars as required by the TCAP. In one embodiment, the information server would provide a Web form accessible by a Web browser. Entries made into supplied fields in the Web form are tagged as having been entered into the particular fields, and parsed as such. The entered terms are then passed along with the field tags, which act to instruct the parser to generate queries directed to appropriate tables and/or fields. In one embodiment, the parser may generate queries in standard SQL by instantiating a search string with the proper join/select commands based on the tagged text entries, wherein the resulting command is provided over the bridge mechanism to the TCAPS as a query. Upon generating query results from the query, the results are passed over the bridge mechanism, and may be parsed for formatting and generation of a new results Web page by the bridge mechanism. Such a new results Web page is then provided to the information server, which may supply it to the requesting Web browser. Also, an information server may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. User Interface A user interface module 917 is stored program code that is executed by the CPU. The user interface may be a conventional graphic user interface as provided by, with, and/or atop operating systems and/or operating environments such as Apple Macintosh OS, e.g., Aqua, Microsoft Windows (NT/XP), Unix X Windows (KDE, Gnome, and/or the like) and/or the like. The user interface may allow for the display, execution, interaction, manipulation, and/or operation of program modules and/or system facilities through textual and/or graphical facilities. The user interface provides a facility through which users may affect, interact, and/or operate a computer system. A user interface may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the user interface communicates with operating systems, other program modules, and/or the like. The user interface may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Web Browser A Web browser module 918 is stored program code that is executed by the CPU. The Web browser may be a conventional hypertext viewing application such as Microsoft Internet Explorer or Netscape Navigator. Secure Web browsing may be supplied with 128 bit (or greater) encryption by way of HTTPS, SSL, and/or the like. Some Web browsers allow for the execution of program modules through facilities such as Java, JavaScript, ActiveX, and/or the like. Web browsers and like information access tools may be integrated into PDAs, cellular telephones, and/or other mobile devices. A Web browser may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the Web browser communicates with information servers, operating systems, integrated program modules (e.g., plug-ins), and/or the like; e.g., it may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Of course, in place of a Web browser and information server, a combined application may be developed to perform similar functions of both. The combined application would similarly affect the obtaining and the provision of information to users, user agents, and/or the like from TCAPS enabled nodes. The combined application may be nugatory on systems employing standard Web browsers. TCAPS Database A TCAPS database module 919 may be embodied in a database and its stored data. The database is stored program code, which is executed by the CPU; the stored program code portion configuring the CPU to process the stored data. The database may be a conventional, fault tolerant, relational, scalable, secure database such as Oracle or Sybase. Relational databases are an extension of a flat file. Relational databases consist of a series of related tables. The tables are interconnected via a key field. Use of the key field allows the combination of the tables by indexing against the key field; i.e., the key fields act as dimensional pivot points for combining information from various tables. Relationships generally identify links maintained between tables by matching primary keys. Primary keys represent fields that uniquely identify the rows of a table in a relational database. More precisely, they uniquely identify rows of a table on the “one” side of a one-to-many relationship. Alternatively, the TCAPS database may be implemented using various standard data-structures, such as an array, hash, (linked) list, struct, structured text file (e.g., XML), table, and/or the like. Such data-structures may be stored in memory and/or in (structured) files. In another alternative, an object-oriented database may be used, such as Frontier, ObjectStore, Poet, Zope, and/or the like. Object databases can include a number of object collections that are grouped and/or linked together by common attributes; they may be related to other object collections by some common attributes. Object-oriented databases perform similarly to relational databases with the exception that objects are not just pieces of data but may have other types of functionality encapsulated within a given object. If the TCAPS database is implemented as a data-structure, the use of the TCAPS database may be integrated into another module such as the TCAPS module. Also, the database may be implemented as a mix of data structures, objects, and relational structures. Databases may be consolidated and/or distributed in countless variations through standard data processing techniques. Portions of databases, e.g., tables, may be exported and/or imported and thus decentralized and/or integrated. In one embodiment, the database module 919 includes three tables 919a-c. A user accounts table 919a includes fields such as, but not limited to: a user name, user address, user authorization information (e.g., user name, password, biometric data, etc.), user credit card, organization, organization account, TCAP unique identifier, account creation data, account expiration date; and/or the like. In one embodiment, user accounts may be activated only for set amounts of time and will then expire once a specified date has been reached. An user data table 919b includes fields such as, but not limited to: a TCAP unique identifier, backup image, data store, organization account, and/or the like. A user programs table 919c includes fields such as, but not limited to: system programs, organization programs, programs to be synchronized, and/or the like. In one embodiment, user programs may contain various user interface primitives, which may serve to update TCAPs. Also, various accounts may require custom database tables depending upon the environments and the types of TCAPs a TCAPS may need to serve. It should be noted that any unique fields may be designated as a key field throughout. In an alternative embodiment, these tables have been decentralized into their own databases and their respective database controllers (i.e., individual database controllers for each of the above tables). Employing standard data processing techniques, one may further distribute the databases over several computer systemizations and/or storage devices. Similarly, configurations of the decentralized database controllers may be varied by consolidating and/or distributing the various database modules 919a-c. The TCAPS may be configured to keep track of various settings, inputs, and parameters via database controllers. A TCAPS database may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the TCAPS database communicates with a TCAPS module, other program modules, and/or the like. The database may contain, retain, and provide information regarding other nodes and data. Crytographic Server A cryptographic server module 920 is stored program code that is executed by the CPU 903, cryptographic processor 926, cryptographic processor interface 927, cryptographic processor device 928, and/or the like. Cryptographic processor interfaces will allow for expedition of encryption and/or decryption requests by the cryptographic module, however, the cryptographic module, alternatively, may run on a conventional CPU. The cryptographic module allows for the encryption and/or decryption of provided data. The cryptographic module allows for both symmetric and asymmetric (e.g., Pretty Good Protection (PGP)) encryption and/or decryption. The cryptographic module may employ cryptographic techniques such as, but not limited to: digital certificates (e.g., X.509 authentication framework), digital signatures, dual signatures, enveloping, password access protection, public key management, and/or the like. The cryptographic module will facilitate numerous (encryption and/or decryption) security protocols such as, but not limited to: checksum, Data Encryption Standard (DES), Elliptical Curve Encryption (ECC), International Data Encryption Algorithm (IDEA), Message Digest 5 (MD5, which is a one way hash function), passwords, Rivest Cipher (RC5), Rijndael, RSA (which is an Internet encryption and authentication system that uses an algorithm developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman), Secure Hash Algorithm (SHA), Secure Socket Layer (SSL), Secure Hypertext Transfer Protocol (HTTPS), and/or the like. Employing such encryption security protocols, the TCAPS may encrypt all incoming and/or outgoing communications and may serve as node within a virtual private network (VPN) with a wider communications network. The cryptographic module facilitates the process of “security authorization” whereby access to a resource is inhibited by a security protocol wherein the cryptographic module effects authorized access to the secured resource. In addition, the cryptographic module may provide unique identifiers of content, e.g., employing and MD5 hash to obtain a unique signature for an digital audio file. A cryptographic module may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. The cryptographic module supports encryption schemes allowing for the secure transmission of information across a communications network to enable a TCAPS module to engage in secure transactions if so desired. The cryptographic module facilitates the secure accessing of resources on TCAPS and facilitates the access of secured resources on remote systems; i.e., it may act as a client and/or server of secured resources. Most frequently, the cryptographic module communicates with information servers, operating systems, other program modules, and/or the like. The cryptographic module may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. TCAPS A TCAPS module 935 is stored program code that is executed by the CPU. The TCAPS affects accessing, obtaining and the provision of information, services, transactions, and/or the like across various communications networks. The TCAPS enables TCAP users to simply access data and/or services across a communications network in a secure manner. The TCAPS extends the storage and processing capacities and capabilities of TCAPs. The TCAPS coordinates with the TCAPS database to identify interassociated items in the generation of entries regarding any related information. A TCAPS module enabling access of information between nodes may be developed by employing standard development tools such as, but not limited to: (ANSI) (Objective-) C (++), Apache modules, binary executables, Java, Javascript, mapping tools, procedural and object oriented development tools, PERL, Python, shell scripts, SQL commands, web application server extensions, WebObjects, and/or the like. In one embodiment, the TCAPS server employs a cryptographic server to encrypt and decrypt communications. A TCAPS module may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the TCAPS module communicates with a TCAPS database, operating systems, other program modules, and/or the like. The TCAPS may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Distributed TCAP The structure and/or operation of any of the TCAPS node controller components may be combined, consolidated, and/or distributed in any number of ways to facilitate development and/or deployment. Similarly, the module collection may be combined in any number of ways to facilitate deployment and/or development. To accomplish this, one may integrate the components into a common code base or in a facility that can dynamically load the components on demand in an integrated fashion. The module collection may be consolidated and/or distributed in countless variations through standard data processing and/or development techniques. Multiple instances of any one of the program modules in the program module collection may be instantiated on a single node, and/or across numerous nodes to improve performance through load-balancing and/or data-processing techniques. Furthermore, single instances may also be distributed across multiple controllers and/or storage devices; e.g., databases. All program module instances and controllers working in concert may do so through standard data processing communication techniques. The configuration of the TCAPS controller will depend on the context of system deployment. Factors such as, but not limited to, the budget, capacity, location, and/or use of the underlying hardware resources may affect deployment requirements and configuration. Regardless of if the configuration results in more consolidated and/or integrated program modules, results in a more distributed series of program modules, and/or results in some combination between a consolidated and distributed configuration, data may be communicated, obtained, and/or provided. Instances of modules consolidated into a common code base from the program module collection may communicate, obtain, and/or provide data. This may be accomplished through intra-application data processing communication techniques such as, but not limited to: data referencing (e.g., pointers), internal messaging, object instance variable communication, shared memory space, variable passing, and/or the like. If module collection components are discrete, separate, and/or external to one another, then communicating, obtaining, and/or providing data with and/or to other module components may be accomplished through inter-application data processing communication techniques such as, but not limited to: Application Program Interfaces (API) information passage; (distributed) Component Object Model ((D)COM), (Distributed) Object Linking and Embedding ((D)OLE), and/or the like), Common Object Request Broker Architecture (CORBA), process pipes, shared files, and/or the like. Messages sent between discrete module components for inter-application communication or within memory spaces of a singular module for intra-application communication may be facilitated through the creation and parsing of a grammar. A grammar may be developed by using standard development tools such as lex, yacc, and/or the like, which allow for grammar generation and parsing functionality, which in turn may form the basis of communication messages within and between modules. Again, the configuration will depend upon the context of system deployment. Tunneling Client Access Point Controller FIG. 10 illustrates one embodiment incorporated into a tunneling client access point (TCAP) controller 1001. Much of the description of the TCAPS of FIG. 9 applies to the TCAP, and as such, the disclosure focuses more upon the variances exhibited in the TCAP. In this embodiment, the TCAP controller 1001 may serve to process, store, search, identify, instruct, generate, match, and/or update data within itself, at a TCAPS, and/or through an AT. The first and foremost difference between the TCAP and the TCAPS is that the TCAP is very small as was shown 130 of FIG. 1. The TCAP may be packaged in plugin sticks, often, smaller than the size of a human thumb. In one embodiment, a TCAP may be hardened for military use. In such an embodiment, the shell 1001 may be composed of metal, and/or other durable composites. Also, components within may be shielded from radiation. In one embodiment, the TCAP controller 1001 may be connected to and/or communicate with entities such as, but not limited to: one or more users from an access terminal 1011b. The access terminal itself may be connected to peripherals such as user input devices (e.g., keyboard 1012a, mouse 1012b, etc.); and/or a communications network 1013 in manner similar to that described in FIG. 9. A TCAP controller 1001 may be based on common computer systems components that may comprise, but are not limited to, components such as: a computer systemization 1002 connected to memory 1029. Optionally, the TCAP controller 1001 may convey information 1058, produce output through an output device 1048, and obtain input from control device 1018. Control Device The control device 1018 may be optionally provided to accept user input to control access to the TCAP controller. In one embodiment, the control device may provide a keypad 1028. Such a keypad would allow the user to enter passwords, personal identification numbers (PIN), and/or the like. In an alternative embodiment, the control device may include a security device 1038. In one embodiment, the security device is a fingerprint integrated circuit (fingerprint IC) that provides biometric fingerprint information such as, but not limited to AuthenTec Inc.'s FingerLoc™ AF-S2™. Either a fingerprint IC and/or other biometric device will provide biometric validation information that may be used to confirm the identity of a TCAP user and ensure that transactions are legitimate. In alternative embodiments, a simple button, heat sensor, and/or other type of user input functionality may be provided solely and/or in concert with other types of control device types. The control device may be connected to the I/O interface, the system bus, or the CPU directly. The output device 1048 is used to provide status information to the user. In one alternative embodiment, the output device is an LCD panel capable of providing alpha numeric and/or graphic displays. In an alternative embodiment, the output device may be a speaker providing audible signals indicating errors and/or actually streaming information that is audible to the user, such as voice alerts. The output device may be connected to the I/O interface, the system bus, or the CPU directly. The conveyance information 1058 component of the TCAP controller may include any number of indicia representing the TCAP's source on the cover 1001. Source conveying indicia may include, but is not limited to: an owner name 1059 for readily verifying a TCAP user; a photo of the owner 1060 for readily verifying a TCAP controller owner; mark designating the source that issued the TCAP 1061, 1001 such as a corporate logo, and/or the like; fanciful design information 1062 for enhancing the visual appearance of the TCAP; and/or the like. It should be noted that the conveyance information 11421 may be positioned anywhere on the cover 1189. Computer Systemization A computer systemization 1002 may comprise a clock 1030, central processing unit (CPU) 1003, a read only memory (ROM) 1006, a random access memory (RAM) 1005, and/or an interface bus 1007, and most frequently, although not necessarily, are all interconnected and/or communicating through a system bus 1004. Optionally the computer systemization may be connected to an internal power source 1086. Optionally, a cryptographic processor 1026 may be connected to the system bus. The system clock typically has a crystal oscillator and provides a base signal. Of course, any of the above components may be connected directly to one another, connected to the CPU, and/or organized in numerous variations employed as exemplified by various computer systems. The CPU comprises at least one low-power data processor adequate to execute program modules for executing user and/or system-generated requests. The CPU may be a microprocessor such as ARM's Application Cores, Embedded Cores, Secure Cores; Motorola's DragonBall; and/or the like processor(s). Power Source The power source 1086 may be of any standard form for powering small electronic circuit board devices such as but not limited to: alkaline, lithium hydride, lithium ion, nickel cadmium, solar cells, and/or the like. In the case of solar cells, the case provides an aperture through which the solar cell protrudes are to receive photonic energy. The power cell 1086 is connected to at least one of the interconnected subsequent components of the TCAP thereby providing an electric current to all subsequent components. In one example, the power cell 1086 is connected to the system bus component 1004. In an alternative embodiment, an outside power source 1086 is provided through a connection across the I/O 1008 interface. For example, a USB and/or IEEE 1394 connection carries both data and power across the connection and is therefore a suitable source of power. Interface Adapters Interface bus(ses) 1007 may accept, connect, and/or communicate to a number of interface adapters, conventionally although not necessarily in the form of adapter cards, such as but not limited to: input output interfaces (I/O) 1008, storage interfaces 1009, network interfaces 1010, and/or the like. Optionally, cryptographic processor interfaces 1027 similarly may be connected to the interface bus. The interface bus provides for the communications of interface adapters with one another as well as with other components of the computer systemization. Interface adapters are adapted for a compatible interface bus. In one embodiment, the interface bus provides I/O 1008 via a USB port. In an alternative embodiment, the interface bus provides I/O via an IEEE 1394 port. In an alternative embodiment, wireless transmitters are employed by interfacing wireless protocol integrated circuits (ICs) for I/O via the interface bus 1007. Storage interfaces 1009 may accept, communicate, and/or connect to a number of storage devices such as, but not limited to: storage devices 1014, removable disc devices, and/or the like. Storage interfaces may employ connection protocols such as, but not limited to a flash memory connector, and/or the like. In one embodiment, an optional network interface may be provide 1010. Input Output interfaces (I/O) 1008 may accept, communicate, and/or connect to an access terminal 1011b. I/O may employ connection protocols such as, but not limited to: Apple Desktop Bus (ADB); Apple Desktop Connector (ADC); IEEE 1394a-b; infrared; PC AT; PS/2; parallel; radio; serial; USB, and/or the like; wireless component; and/or the like. Wireless Component In one embodiment a wireless component may comprise a Bluetooth chip disposed in communication with a transceiver 1043 and a memory 1029 through the interface bus 1007 and/or system bus 1004. The transceiver may be either external to the Bluetooth chip, or integrated within the Bluetooth chip itself. The transceiver is a radio frequency (RF) transceiver operating in the range as required for Bluetooth transmissions. Further, the Bluetooth chip 1044 may integrate an input/output interface (I/O) 1066. The Bluetooth chip and its I/O may be configured to interface with the TCAP controller through the interface bus, the system buss, and/or directly with the CPU. The I/O may be used to interface with other components such as an access terminal 1011b equipped with similar wireless capabilities. In one embodiment, the TCAP may optionally interconnect wirelessly with a peripheral device 912 and/or a control device 911 of FIG. 9. In one example embodiment, the I/O may be based on serial line technologies, a universal serial bus (USB) protocol, and/or the like. In an alternative embodiment, the I/O may be based on the ISO 7816-3 standard. It should be noted that the Bluetooth chip in an alternative embodiment may be replaced with an IEEE 802.11b wireless chip. In another embodiment, both a Bluetooth chip and an IEEE 802.11b wireless chip may be used to communicate and or bridge communications with respectively enabled devices. It should further be noted that the transceiver 1043 may be used to wirelessly communicate with other devices powered by Bluetooth chips and/or IEEE 802.11b chips and/or the like. The ROM can provide a basic instruction set enabling the Bluetooth chip to use its I/O to communicate with other components. A number of Bluetooth chips are commercially available, and may be used as a Bluetooth chip in the wireless component, such as, but not limited to, CSR's BlueCore line of chips. If IEEE 802.11b functionality is required, a number of chips are commercially available for the wireless component as well. Cryptographic units such as, but not limited to, microcontrollers, processors 1026, and/or interfaces 1027 may be attached, and/or communicate with the TCAP controller. A Secure Core component commonly manufactured by ARM, Inc. and may be used for and/or within cryptographic units. Memory Generally, any mechanization and/or embodiment allowing a processor to affect the storage and/or retrieval of information is regarded as memory 1029. However, memory is a fungible technology and resource, thus, any number of memory embodiments may be employed in lieu of or in concert with one another. It is to be understood that a TCAP controller and/or a computer systemization may employ various forms of memory 1029. In a typical configuration, memory 1029 will include ROM 1006, RAM 1005, and a storage device 1014. A storage device 1014 may be any conventional computer system storage. Storage devices may include flash memory, micro hard drives, and/or the like. Module Collection The memory 1029 may contain a collection of program and/or database modules and/or data such as, but not limited to: operating system module(s) 1015 (operating system); information server module(s) 1016 (information server); user interface module(s) 1017 (user interface); Web browser module(s) 1018 (Web browser); database(s) 1019; cryptographic server module(s) 1020 (cryptographic server); access terminal module 1021; TCAP module(s) 1035; and/or the like (i.e., collectively a module collection). These modules may be stored and accessed from the storage devices and/or from storage devices accessible through an interface bus. Although non-conventional software modules such as those in the module collection, typically, are stored in a local storage device 1014, they may also be loaded and/or stored in memory such as: peripheral devices, RAM, remote storage facilities through an access terminal, communications network, ROM, various forms of memory, and/or the like. In one embodiment, all data stored in memory is encrypted by employing the cryptographic server 1020 as described in further detail below. In one embodiment, the ROM contains a unique TCAP identifier. For example, the TCAP may contain a unique digital certificate, number, and/or the like, which may be used for purposes of verification and encryption across a network and/or in conjunction with a TCAPS. Operating System The operating system module 1015 is executable program code facilitating the operation of a TCAP controller. Typically, the operating system facilitates access of I/O, network interfaces, peripheral devices, storage devices, and/or the like. The operating system may be a highly fault tolerant, scalable, and secure system such as Linux, and/or the like operating systems. However, more limited and/or less secure operating systems also may be employed such as Java runtime OS, and/or the like. An operating system may communicate to and/or with other modules in a module collection, including itself, and/or the like. Most frequently, the operating system communicates with other program modules, user interfaces, and/or the like. For example, the operating system may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. The operating system, once executed by the CPU, may enable the interaction with an access terminal, communications networks, data, I/O, peripheral devices, program modules, memory, user input devices, and/or the like. The operating system may provide communications protocols that allow the TCAP controller to communicate with other entities through an access terminal. Various communication protocols may be used by the TCAP controller as a subcarrier transport mechanism for interaction, such as, but not limited to: TCP/IP, USB, and/or the like. Information Server An information server module 1016 is stored program code that is executed by the CPU. The information server may be a conventional Internet information server such as, but not limited to Apache Software Foundation's Apache, and/or the like. The information server may allow for the execution of program modules through facilities such as. Active Server Page (ASP), ActiveX, (ANSI) (Objective-) C (++), Common Gateway Interface (CGI) scripts, Java, JavaScript, Practical Extraction Report Language (PERL), Python, WebObjects, and/or the like. The information server may support secure communications protocols such as, but not limited to, File Transfer Protocol (FTP); HyperText Transfer Protocol (HTTP); Secure Hypertext Transfer Protocol (HTTPS), Secure Socket Layer (SSL), and/or the like. The information server provides results in the form of Web pages to Web browsers, and allows for the manipulated generation of the Web pages through interaction with other program modules. An information server may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the information server communicates with the TCAP database 1019, operating systems, other program modules, user interfaces, Web browsers, and/or the like. Access to TCAP database may be achieved through a number of database bridge mechanisms such as through scripting languages as enumerated below (e.g., CGI) and through inter-application communication channels as enumerated below (e.g., CORBA, WebObjects, etc.). Any data requests through a Web browser are parsed through the bridge mechanism into appropriate grammars as required by the TCAP. In one embodiment, the information server would provide a Web form accessible by a Web browser. Entries made into supplied fields in the Web form are tagged as having been entered into the particular fields and parsed as such. The entered terms are then passed along with the field tags, which act to instruct the parser to generate queries directed to appropriate tables and/or fields. In one embodiment, the parser may generate queries in standard SQL by instantiating a search string with the proper join/select commands based on the tagged text entries, wherein the resulting command is provided over the bridge mechanism to the TCAP as a query. Upon generating query results from the query, the results are passed over the bridge mechanism, and may be parsed for formatting and generation of a new results Web page by the bridge mechanism. Such a new results Web page is then provided to the information server, which may supply it to the requesting Web browser. Also, an information server may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. User Interface A user interface module 1017 is stored program code that is executed by the CPU. The user interface may be a conventional graphic user interface as provided by, with, and/or atop operating systems and/or operating environments such as Apple Macintosh OS, e.g., Aqua, Microsoft Windows (NT/XP), Unix X Windows (KDE, Gnome, and/or the like), and/or the like. The TCAP may employ code natively compiled for various operating systems, or code compiled using Java. The user interface may allow for the display, execution, interaction, manipulation, and/or operation of program modules and/or system facilities through textual and/or graphical facilities. The user interface provides a facility through which users may affect, interact, and/or operate a computer system. A user interface may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the user interface communicates with operating systems, other program modules, and/or the like. The user interface may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Web Browser A Web browser module 1018 is stored program code that is executed by the CPU. A small-scale embedded Web browser may allow the TCAP to access and communicate with an attached access terminal, and beyond across a communications network. An example browser is Blazer, Opera, FireFox, etc. A browsing module may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Of course, in place of a Web browser and information server, a combined application may be developed to perform similar functions of both. The combined application would similarly affect the obtaining and the provision of information to users, user agents, and/or the like from TCAP enabled nodes. The combined application may be nugatory on systems employing standard Web browsers. TCAP Database A TCAP database module 1019 may be embodied in a database and its stored data. The database is stored program code, which is executed by the CPU; the stored program code portion configuring the CPU to process the stored data. In one embodiment, the TCAP database may be implemented using various standard data-structures, such as an array hash, (linked) list, struct, structured text file (e.g., XML), table, and/or the like. Such data-structures may be stored in memory and/or in (structured) files. If the TCAP database is implemented as a data-structure, the use of the TCAP database may be integrated into another module such as the TCAP module. Databases may be consolidated and/or distributed in countless variations through standard data processing techniques. Portions of databases, e.g., tables, may be exported and/or imported and thus decentralized and/or integrated. In one embodiment, the database module 1019 includes three tables 1019a-c. A user accounts table 1019a includes fields such as, but not limited to: a user name, user address, user authorization information (e.g., user name, password, biometric data, etc.), user credit card, organization, organization account, TCAP unique identifier, account creation data, account expiration date; and/or the like. In one embodiment, user accounts may be activated only for set amounts of time and will then expire once a specified date has been reached. An user data table 1019b includes fields such as, but not limited to: a TCAP unique identifier, backup image, data store, organization account, and/or the like. In one embodiment, the entire TCAP memory 1029 is processes into an image and spooled to a TCAPS for backup storage. A user programs table 1019c includes fields such as, but not limited to: system programs, organization programs, programs to be synchronized, and/or the like. It should be noted that any unique fields may be designated as a key field throughout. In an alternative embodiment, these tables have been decentralized into their own databases and their respective database controllers (i.e., individual database controllers for each of the above tables). Employing standard data processing techniques, one may further distribute the databases over several computer systemizations and/or storage devices. Similarly, configurations of the decentralized database controllers may be varied by consolidating and/or distributing the various database modules 1019a-c. The TCAP may be configured to keep track of various settings, inputs, and parameters via database controllers. A TCAP database may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the TCAP database communicates with a TCAP module, other program modules, and/or the like. The database may contain, retain, and provide information regarding other nodes and data. Cryptographic Server A cryptographic server module 1020 is stored program code that is executed by the CPU 1003, cryptographic processor 1026, cryptographic processor interface 1027, and/or the like. Cryptographic processor interfaces will allow for expedition of encryption and/or decryption requests by the cryptographic module; however, the cryptographic module, alternatively, may run on a conventional CPU. The cryptographic module allows for the encryption and/or decryption of provided data. The cryptographic module allows for both symmetric and asymmetric (e.g., Pretty Good Protection (PGP)) encryption and/or decryption. The cryptographic module may employ cryptographic techniques such as, but not limited to: digital certificates (e.g., X.509 authentication framework), digital signatures, dual signatures, enveloping, password access protection, public key management, and/or the like. The cryptographic module will facilitate numerous (encryption and/or decryption) security protocols such as, but not limited to: checksum, Data Encryption Standard (DES), Elliptical Curve Encryption (ECC), International Data Encryption Algorithm (IDEA), Message Digest 5 (MD5, which is a one way hash function) passwords, Rivest Cipher (RC5), Rijndael, RSA (which is an Internet encryption and authentication system that uses an algorithm developed in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman), Secure Hash Algorithm (SHA), Secure Socket Layer (SSL), Secure Hypertext Transfer Protocol (HTTPS), and/or the like. The cryptographic module facilitates the process of “security authorization” whereby access to a resource is inhibited by a security protocol wherein the cryptographic module effects authorized access to the secured resource. In addition, the cryptographic module may provide unique identifiers of content, e.g., employing and MD5 hash to obtain a unique signature for an digital audio file. A cryptographic module may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. The cryptographic module supports encryption schemes allowing for the secure transmission of information across a communications network to enable a TCAP module to engage in secure transactions if so desired. The cryptographic module facilitates the secure accessing of resources on TCAP and facilitates the access of secured resources on remote systems; i.e., it may act as a client and/or server of secured resources. Most frequently, the cryptographic module communicates with information servers, operating systems, other program modules, and/or the like. The cryptographic module may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. In one embodiment, the TCAP employs the cryptographic server to encrypt all data stored in memory 1029 based on the TCAP's unique ID and user's authorization information. In another embodiment, the TCAP employs the cryptographic server to encrypt all data sent through the access terminal based in the TCAP's unique ID and user's authorization information. TCAP A TCAP module 1035 is stored program code that is executed by the CPU. The TCAP affects accessing, obtaining and the provision of information, services, storage, transactions, and/or the like within its memory and/or across various communications networks. The TCAP enables users to simply access data and/or services from any location where an access terminal is available. It provides secure, extremely low powerful and ultra portable access to data and services that were heretofore impossible. The TCAP coordinates with the TCAP database to identify interassociated items in the generation of entries regarding any related information. A TCAP module enabling access of information between nodes may be developed by employing standard development tools such as, but not limited to: (ANSI) (Objective-) C (++), Apache modules, binary executables, Java, Javascript, mapping tools, procedural and object oriented development tools, PERL, Python, shell scripts, SQL commands, web application server extensions, WebObjects, and/or the like. In one embodiment, the TCAP server employs a cryptographic server to encrypt and decrypt communications. A TCAP module may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the TCAP module communicates with a TCAP database, a TCAP access terminal module 1021 running on an access terminal 1011b, operating systems, other program modules, and/or the like. The TCAP may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data-communications, requests, and/or responses. Access Terminal Module An access terminal module 1021 is stored program code that is executed by a CPU. In one embodiment, the TCAP allows the access terminal 1011 b to access its memory 1029 across its I/O 1008 and the access terminal executes the module. The access terminal module affects accessing, obtaining and the provision of information, services, storage, transactions, and/or the like within the TCAP's and access terminal's memory and/or across various communications networks. The access terminal module 1021 acts as a bridge through which the TCAP can communicate with communications network, and through which users may interact with the TCAP by using the I/O of the access terminal. The access terminal module coordinates with the TCAP module 1035 to send data and communications back and forth. A access terminal module enabling access of information between the TCAP and access terminal may be developed by employing standard development tools such as, but not limited -to: (ANSI) (Objective-) C (++), Apache modules, binary executables, Java, Javascript, mapping tools, procedural and object oriented development tools, PERL, Python, shell scripts, SQL commands, web application server extensions, WebObjects, and/or the like. In one embodiment, the access terminal module is compiled for target access terminal platform, e.g., for Windows. In an alternative embodiment, a processor independent approach is taken, e.g., Java is used, so that the access terminal module will run on multiple platforms. In another embodiment, the TCAP server employs a cryptographic server to encrypt and decrypt communications as between it, the TCAP, and outside servers. A access terminal module may communicate to and/or with other modules in a module collection, including itself, and/or facilities of the like. Most frequently, the access terminal module communicates with a TCAP, other program modules, and/or the like. The access terminal module may contain, communicate, generate, obtain, and/or provide program module, system, user, and/or data communications, requests, and/or responses. Distributed TCAP The structure and/or operation of any of the TCAP node controller components may be combined, consolidated, and/or distributed in any number of ways to facilitate development and/or deployment. Similarly, the module collection may be combined in any number of ways to facilitate deployment and/or development. To accomplish this, one may integrate the components into a common code base or in a facility that can dynamically load the components on demand in an integrated fashion. The module collection may be consolidated and/or distributed in countless variations through standard data processing and/or development techniques. Multiple instances of any one of the program modules in the program module collection may be instantiated on a single node, and/or across numerous nodes to improve performance through load-balancing and/or data-processing techniques. Furthermore, single instances may also be distributed across multiple controllers and/or storage devices; e.g., databases. All program module instances and controllers working in concert may do so through standard data processing communication techniques. The configuration of the TCAP controller will depend on the context of system deployment. Factors such as, but not limited to, the budget, capacity, location, and/or use of the underlying hardware resources may affect deployment requirements and configuration. Regardless of if the configuration results in more consolidated and/or integrated program modules, results in a more distributed series of program modules, and/or results in some combination between a consolidated and distributed configuration, data may be communicated, obtained, and/or provided. Instances of modules consolidated into a common code base from the program module collection may communicate, obtain, and/or provide data. This may be accomplished through intra-application data processing communication techniques such as, but not limited to: data referencing (e.g., pointers), internal messaging, object instance variable communication, shared memory space, variable passing, and/or the like. If module collection components are discrete, separate, and/or external to one another, then communicating, obtaining, and/or providing data with and/or to other module components may be accomplished through inter-application data processing communication techniques such as, but not limited to: Application Program Interfaces (API) information passage; (distributed) Component Object Model ((D)COM), (Distributed) Object Linking and Embedding ((D)OLE), and/or the like), Common Object Request Broker Architecture (CORBA), process pipes, shared files, and/or the like. Messages sent between discrete module components for inter-application communication or within memory spaces of a singular module for intra-application communication may be facilitated through the creation and parsing of a grammar. A grammar may be developed by using standard development tools such as lex, yacc, and/or the like, which allow for grammar generation and parsing functionality, which in turn may form the basis of communication messages within and between modules. Again, the configuration will depend upon the context of system deployment. The entirety of this disclosure (including the Cover Page, Title, Headings, Field, Background, Summary, Brief Description of the Drawings, Detailed Description, Claims, Abstract, Figures, and otherwise) shows by way of illustration various embodiments in which the claimed inventions may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed principles. It should be understood that they are not representative of all claimed inventions. As such, certain aspects of the disclosure have not been discussed herein. That alternate embodiments may not have been presented for a specific portion of the invention or that further undescribed alternate embodiments may be available for a portion is not to be considered a disclaimer of those alternate embodiments. It will be appreciated that many of those undescribed embodiments incorporate the same principles of the invention and others are equivalent. Thus, it is to be understood that other embodiments may be utilized and functional, logical, organizational, structural and/or topological modifications may be made without departing from the scope and/or spirit of the disclosure. As such, all examples and/or embodiments are deemed to be non-limiting throughout this disclosure. Also, no inference should be drawn regarding those embodiments discussed herein relative to those not discussed herein other than for purposes of space and reducing repetition. For instance, it is to be understood that the logical and/or topological structure of any combination of any program modules (a module collection), other components and/or any present feature sets as described in the figures and/or throughout are not limited to a fixed operating order and/or arrangement, but rather, any disclosed order is exemplary and all equivalents, regardless of order, are contemplated by the disclosure. Furthermore, it is to be understood that such features are not limited to serial execution, but rather, any number of threads, processes, services, servers, and/or the like that may execute asynchronously, simultaneously, synchronously, and/or the like are contemplated by the disclosure. As such, some of these features may be mutually contradictory, in that they cannot be simultaneously present in a single embodiment. Similarly, some features are applicable to one aspect of the invention, and inapplicable to others. In addition, the disclosure includes other inventions not presently claimed. Applicant reserves all rights in those presently unclaimed inventions including the right to claim such inventions, file additional applications, continuations, continuations in part, divisions, and/or the like thereof. As such, it should be understood that advantages, embodiments, examples, functional, features, logical, organizational, structural, topological, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims. | <SOH> BACKGROUND <EOH>Portable Computing and Storage Computing devices have been becoming smaller over time. Currently, some of the smallest computing devices are in the form of personal digital assistants (PDAs). Such devices usually come with a touch screen, an input stylus and/or mini keyboard, and battery source. These devices, typically, have storage capacities around 64 MB. Examples of these devices include Palm's Palm Pilot. Information Technology Systems Typically, users, which may be people and/or other systems, engage information technology systems (e.g., commonly computers) to facilitate information processing. In turn, computers employ processors to process information; such processors are often referred to as central processing units (CPU). A common form of processor is referred to as a microprocessor. A computer operating system, which, typically, is software executed by CPU on a computer, enables and facilitates users to access and operate computer information technology and resources. Common resources employed in information technology systems include: input and output mechanisms through which data may pass into and out of a computer; memory storage into which data may be saved; and processors by which information may be processed. Often information technology systems are used to collect data for later retrieval, analysis, and manipulation, commonly, which is facilitated through database software. Information technology systems provide interfaces that allow users to access and operate various system components. User Interface The function of computer interfaces in some respects is similar to automobile operation interfaces. Automobile operation interface elements such as steering wheels, gearshifts, and speedometers facilitate the access, operation, and display of automobile resources, functionality, and status. Computer interaction interface elements such as check boxes, cursors, menus, scrollers, and windows (collectively and commonly referred to as widgets) similarly facilitate the access, operation, and display of data and computer hardware and operating system resources, functionality, and status. Operation interfaces are commonly called user interfaces. Graphical user interfaces (GUIs) such as the Apple Macintosh Operating System's Aqua, Microsoft's Windows XP, or Unix's X-Windows provide a baseline and means of accessing and displaying information, graphically, to users. Networks Networks are commonly thought to comprise of the interconnection and interoperation of clients, servers, and intermediary nodes in a graph topology. It should be noted that the term “server” as used herein refers generally to a computer, other device, software, or combination thereof that processes and responds to the requests of remote users across a communications network. Servers serve their information to requesting “clients.” The term “client” as used herein refers generally to a computer, other device, software, or combination thereof that is capable of processing and making requests and obtaining and processing any responses from servers across a communications network. A computer, other device, software, or combination thereof that facilitates, processes information and requests, and/or furthers the passage of information from a source user to a destination user is commonly referred to as a “node.” Networks are generally thought to facilitate the transfer of information from source points to destinations. A node specifically tasked with furthering the passage of information from a source to a destination is commonly called a “router.” There. are many forms of networks such as Local Area Networks (LANs), Pico networks, Wide Area Networks (WANs), Wireless Networks (WLANs), etc. For example, the Internet is generally accepted as being an interconnection of a multitude of networks whereby remote clients and servers may access and interoperate with one another. | <SOH> SUMMARY <EOH>Although all of the aforementioned portable computing systems exist, no effective solution to securely access, execute, and process data is available in an extremely compact form. Currently, PDAs, which are considered among the smallest portable computing solution, are bulky, provide uncomfortably small user interfaces, and require too much power to maintain their data. Current PDA designs are complicated and cost a lot because they require great processing resources to provide custom user interfaces and operating systems. Further, current PDAs are generally limited in the amount of data they can store or access. No solution exists that allows users to employ traditional large user interfaces they are already comfortable with, provides greater portability, provides greater memory footprints, draws less power, and provides security for data on the device. As such, the disclosed tunneling client access point (TCAP) is very easy to use; at most it requires the user to simply plug the device into any existing and available desktop or laptop computer, through which, the TCAP can make use of a traditional user interface and input/output (I/O) peripherals, while the TCAP itself, otherwise, provides storage, execution, and/or processing resources. Thus, the TCAP requires no power source to maintain its data and allows for a highly portable “thumb” footprint. Also, by providing the equivalent of a plug-n-play virtual private network (VPN), the TCAP provides certain kinds of accessing of remote data in an easy and secure manner that was unavailable in the prior art. In accordance with certain aspects of the disclosure, the above-identified problems of limited computing devices are overcome and a technical advance is achieved in the art of portable computing and data access. An exemplary tunneling client access point (TCAP) includes a method to dispose a portable storage device in communication with a terminal. The method includes providing the memory for access on the terminal, executing processing instructions from the memory on the terminal to access the terminal, communicating through a conduit, and processing the processing instructions. In accordance with another embodiment, a portable tunneling storage processor is disclosed. The apparatus has a memory and a processor disposed in communication with the memory, and configured to issue a plurality of processing instructions stored in the memory. Also, the apparatus has a conduit for external communications disposed in communication with the processor, configured to issue a plurality of communication instructions as provided by the processor, configured to issue the communication instructions as signals to engage in communications with other devices having compatible conduits, and configured to receive signals issued from the compatible conduits. | 20040323 | 20101228 | 20050929 | 70687.0 | 1 | BILGRAMI, ASGHAR H | APPARATUS, METHOD AND SYSTEM FOR A TUNNELING CLIENT ACCESS POINT | SMALL | 0 | ACCEPTED | 2,004 |
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10,807,861 | ACCEPTED | Compound having an epoxy group and a chalcone group, method of preparing the same, and photoresist composition comprising the same | A compound including an epoxy group that has a heat curing property and a chalcone group that has a radiation curing property is represented by the following formula: wherein n is an integer from 1 to 10,000, and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The compound has a high curing efficiency. A photoresist composition including the compound above substantially prevents the formation of remnant in a photoresist pattern used in the manufacturing of a color filter. In addition, the color filter pattern that is formed using the photoresist composition has high color reproductivity and brightness. | 1. A compound comprising an epoxy group and a chalcone group represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. 2. The compound according to claim 1, wherein the compound has a weight average molecular weight of about 800 to about 20,000. 3. A process for preparing a compound including an epoxy group and a chalcone group comprising: reacting bis(4-4′-hydroxy)chalcone with epichorohydrin in the presence of an alkali metal salt to synthesize a compound represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. 4. The process of claim 3 further comprising reacting bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone with a paratoluene sulfonic acid in the presence of an alcohol to synthesize the bis(4-4′-hydroxy)chalcone. 5. The process of claim 4 further comprising reacting 4-(2-tetrahydro-2H-pyranoxy)acetohenone with 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde in the presence of an alkali metal salt to synthesize the bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone. 6. The process of claim 5 further comprising reacting 4-hydroxy benzaldehyde with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde. 7. The process of claim 5 further comprising reacting 4-hydroxy acetophenone with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)acetohenone. 8. The process of claim 3, wherein the compound has a weight average molecular weight of about 800 to about 20,000. 9. The process of claim 3, wherein the alcohol is ethanol. 10. The process of claim 3, wherein the alkali metal salt is sodium hydroxide or potassium hydroxide. 11. A resist composition comprising: (a) a compound comprising an epoxy group and a chalcone group represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group; (b) a curing agent; and (c) an organic solvent. 12. The resist composition of claim 11, wherein the resist composition includes about 5 to about 35 parts by weight of the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. 13. The resist composition of claim 11, wherein the organic solvent is propylene glycol monomethyl ether acetate, ethyl ethoxy acetate, or cyclohexanone. 14. The resist composition of claim 11 further comprising an acrylate resin. 15. The resist composition of claim 14, wherein the resist composition includes about 5 to about 35 parts by weight of a combination of the acrylate resin and the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. 16. The resist composition of claim 11 further comprising a pigment, wherein the pigment is dissolved in a solvent. 17. The resist composition of claim 16 further comprising a dispersant for dispersing the pigment in the photoresist composition. 18. The resist composition of claim 11 further comprising a photo-initiator. 19. The resist composition of claim 18, wherein the photo-initiator is benzi dimethyl ketal, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, or bis(trichloromethly)-s-triazine derivative. 20. The resist composition of claim 11, wherein the resist composition is used in patterning a color filter in a liquid crystal display. 21. The resist composition according to claim 11, wherein the compound has a weight average molecular weight of about 800 to about 20,000. 22. The resist composition according to claim 16, wherein the pigment is a red, blue, green, yellow, or violet pigment. 23. The resist composition according to claim 11, wherein the curing agent is a dipentaerithritol hexaacrylate or a trimethylolpropane trimethacrylate. 24. A method for forming a color resist pattern, comprising the steps of: applying a layer of a first color resist composition to a black matrix on a substrate to form a first color resist layer, wherein the first color resist composition includes a compound having a chalcone and an epoxy group, a curing agent, an organic solvent, and a pigment; baking the first color resist layer, wherein the organic solvent is evaporated; disposing a first mask having patterns over the first color resist layer; exposing a portion of the first color resist layer through the first mask; developing the exposed first color resist layer, wherein the exposed portion of the first color resist is dissolved in a developing solution; and heating the substrate with the developed first color resist layer, thereby forming a first color resist pattern. 25. The method of claim 24, wherein the black matrix includes a single or double layer of chromium oxide. 26. The method of claim 24, wherein baking the layer of the color resist composition is performed at a temperature of about 80 to about 130° C. 27. The method of claim 24, wherein the developing solution is hydroxides of alkali metals, ammonium hydroxides, or tetramethyl ammonium hydroxides. 28. The method of claim 24 further comprising forming at least a second color resist pattern over the first color resist pattern, wherein forming the at least second color resist pattern comprises the steps of: applying a layer of a second color resist composition to the first color resist pattern to form a second color resist layer, wherein the second color resist composition includes a compound having a chalcone and an epoxy group, a curing agent, an organic solvent, and a pigment; baking the second color resist layer, wherein the organic solvent is evaporated; disposing a second mask having patterns over the second color resist layer; exposing a portion of the second color resist layer through the second mask; developing the second color resist layer, wherein the exposed portion of the second color resist is dissolved in a developing solution; and heating the substrate with the developed second color resist layer, thereby forming a second color resist pattern. 29. The method of claim 24, wherein heating of the substrate is performed at a temperature in the range of about 90 to about 140° C. 30. The method of claim 24, wherein the compound having a chalcone and an epoxy group is represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. 31. The method of claim 24, wherein the pigment is a red, blue, green, yellow, or violet pigment. 32. The method of claim 30, wherein the compound has a weight average molecular weight of about 800 to about 20,000. 33. The method of claim 28, wherein the compound having a chalcone and an epoxy group is represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. 34. The method of claim 33, wherein the compound has a weight average molecular weight of about 800 to about 20,000. 35. The method of claim 28, wherein the pigment is a red, blue, green, yellow, or violet pigment. | CROSS-REFERENCE TO RELATED APPLICANTIONS This application claims priority from Korean Patent Application No. 2003-75086 filed on Oct. 27, 2003, which is incorporated by reference in its entirety. BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates, generally, to a compound having an epoxy group and a chalcone group, a method of preparing the same, and a photoresist composition comprising the same. More particularly, the present invention relates to a compound having an epoxy group that has a heat curing property and a chalcone group that has a radiation curing property, a method of preparing the same, and a photoresist composition comprising the same. 2. Discussion of the Related Art Liquid crystal display apparatuses (LCDs) are widely used in various devices, such as cellular phones, billboards, computer monitors, televisions, etc., because of the many advantages LCDs provide. These advantages include much lower power consumption than other display devices and being thinner and lighter than cathode ray tubes. Generally, to display an image, an LCD apparatus includes an LCD panel and a backlight assembly for supplying light to the LCD panel. The LCD panel includes liquid crystal interposed between two glass substrates. Transmittance of light through the LCD panel is adjusted by controlling and varying the voltage applied to the pixels of the LCD panel. To display color, an LCD apparatus can use three subpixels with color filters, e.g., a red filter, a green filter and a blue filter, to create each color pixel. The transmitted light that passes through the color filters is additively mixed to display a full color screen. For high color reproductivity and brightness close to natural color, the liquid crystal display apparatus needs to have high resolution and light efficiency, and the color filter must be precisely patterned. Photoresist compositions are used for patterning color filters. A conventional photoresist composition includes an acrylate resin, a curing agent and an organic solvent. The photoresist composition may further include a pigment when used for manufacturing a color filter. The acrylate resin has a radiation curing property. The acrylate resin provides a photo cross-linking reaction during an exposure process and then acts as a binder between a pattern and the pigment. In the conventional photoresist compositions, the acrylate resin is usually not completely cured. Hence, a molecular interaction occurs between the surface of a photoresist pattern and a subsequently applied photoresist composition or dispersant for the pigment, thereby generating a photoresist composition remnant. The remnant deteriorates the color characteristics and reduces brightness of the color filter. Moreover, the remnant may cause failures in a junction to a pixel electrode. In particular, when a photoresist multilayer pattern is formed, a color coordinate may be moved, thereby reducing the brightness of the color filter. Therefore, a need exists for a photoresist composition that prevents the formation of a remnant in a photoresist pattern used in forming a color filter to provide a color filter having improved color reproductivity and brightness. SUMMARY OF THE INVENTION It is a feature of the present invention to provide a compound having an epoxy group that has a heat curing property and a chalcone group that has a radiation curing property. It is another feature of the present invention to provide a method of preparing the compound. It is still another feature of the present invention to provide a photoresist composition including the composition. Exemplary Embodiments of the present invention are directed toward a composition comprising an epoxy group and a chalcone group. The compound comprising an epoxy group and a chalcone group is represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. In addition, the compound has a weight average molecular weight of about 800 to about 20,000. According to another exemplary embodiment, a process for preparing a compound including an epoxy group and a chalcone group is provided. The process comprises reacting bis(4-4′-hydroxy)chalcone with epichorohydrin in the presence of an alkali metal salt to synthesize a compound represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The process may also include reacting bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone with a paratoluene sulfonic acid in the presence of an alcohol to synthesize the bis(4-4′-hydroxy)chalcone. In addition, the process may include reacting 4-(2-tetrahydro-2H-pyranoxy)acetohenone with 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde in the presence of an alkali metal salt to synthesize the bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone. Further, the process may include reacting 4-hydroxy benzaldehyde with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde. Furthermore, the process may include reacting 4-hydroxy acetophenone with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)acetohenone. According to yet another exemplary embodiment, a resist composition including a compound having an epoxy group and a chalcone group is provided. The resist composition comprising a curing agent, an organic solvent, and a compound comprising an epoxy group and a chalcone group represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group; In addition, the resist composition may include about 5 to about 35 parts by weight of the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. Further, the resist composition may include an acrylate resin. The resist composition may also include about 5 to about 35 parts by weight of a combination of the acrylate resin and the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. According to still yet another exemplary embodiment, a method for forming a color resist pattern is provided. The method for forming a color resist pattern comprising the steps of applying a layer of a first color resist composition to a black matrix on a substrate to form a first color resist layer, wherein the first color resist composition includes a compound having a chalcone and an epoxy group, a curing agent, an organic solvent, and a pigment, baking the first color resist layer, wherein the organic solvent is evaporated, disposing a first mask having patterns over the first color resist layer, exposing a portion of the first color resist layer through the first mask, developing the exposed first color resist layer, wherein the exposed portion of the first color resist is dissolved in a developing solution, and heating the substrate with the developed first color resist layer, thereby forming a first color resist pattern. These and other exemplary embodiments, features, aspects, and advantages of the present invention will be described in more detail and become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are cross-sectional views illustrating a formation of a color resist pattern using a compound according to an exemplary embodiment of the present invention. FIG. 2 is a NMR spectrum of the compound obtained in Example 1 having an epoxy group and a chalcone group. FIG. 3A represents infrared spectra of the compound obtained in Example 1 with respect to time. FIG. 3B represents enlarged infrared spectra of FIG. 3A having a wave number of 1500 to 1700 cm−1. FIG. 4 is a graph illustrating color characteristics of a monolayer and multilayer using a conventional photoresist composition of Comparative Example 1. FIG. 5 is an electron microscope photograph illustrating the shape of the color resist pattern obtained in Experiment 2. FIG. 6 is an electron microscope photograph illustrating the surface condition of a portion of the color resist pattern obtained in Experiment 2. FIG. 7 is an electron microscope photograph illustrating the shape of the color resist pattern obtained in Comparative Experiment 2. FIG. 8 is an electron microscope photograph illustrating the surface condition of a portion of the color resist pattern obtained in Comparative Experiment 2. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter the exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Compound Havinci an Epoxy Group and a Chalcone Group A compound according to the present invention comprising an epoxy group and a chalcone group is represented by the following formula (I). wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The epoxy group of compound I has a heat curing property and the chalcone group of compound I has a radiation curing property. The compound has a weight average molecular weight of about 800 to about 20,000. The weight average molecular weight of the compound can be determined using a gel permission chromatography (GPC). When the weight average molecular weight of the compound is more than 20,000, the viscosity of the compound increases. When the weight average molecular weight of the composition is less than 800, the compound is excessively used in a photoresist composition, which is not preferable. In formula (I), the integer n represents a repeat unit of a polymer. As the integer n increases, the compound has more chalcone groups than epoxy groups, thereby imparting the characteristic, radiation curing property, of the chalcone group to the compound. The radiation curing property of the chalcone group is caused by the molecular activation of double bonds in a main chain. In addition, after a curing process, the chalcone group becomes harder because the chalcone group has a benzene ring. Substituents in the compound represent additional characteristics of the compound other than the characteristics from the main chain. For instance, when comparing solubility in a nonpolar organic solvent of the compounds with and without substitutents, the solubility increases if each of the substituents R1, R2, R3, R4, R5, R6, R7 and R8 is an alkyl group, alkoxy group or halogen atom, and the solubility decreases if each of the substituents R1, R2, R3, R4, R5, R6, R7 and R8 is a nitro group, based on the solubility when each of the substituents R1, R2, R3, R4, R5, R6, R7 and R8 is a hydrogen atom. Method of Preparing a Compound Having the Epoxy Group and the Chalcone group The compound of formula (I) is produced by polymerizing bis(4,4′-hydroxy)chalcones of formula (II) with epichlorohydrin: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The polymerization reaction is carried out in the presence of an alkali metal salt. Examples of the alkali metal salt include sodium hydroxide, potassium hydroxide, etc. The mechanism of the above reaction is as follows: wherein n, R1, R2, R3, R4, R5, R6, R7 and R8 are as described above. In particular, two end hydroxyl groups in bis(4,4′-hydroxy)chalcones of formula (II) react with epichlorohydrin. Thus, epoxy groups are formed at both ends of bis(4,4′-hydroxy)chalcones. The epoxy rings formed at the ends of the bis(4,4′-hydroxy)chalcones are opened in the presence of an alkali metal salt, and then the open epoxy rings of a bis(4,4′-hydroxy)chalcone react with other open epoxy rings of another bis(4,4′-hydroxy)chalcone to form a polymer resin compound of formula (I). After the reaction is completed, a compound having epoxy groups at both ends and a chalcone group inside the main chain is obtained. Bis(4,4′-hydroxy)chalcones of formula (II) are prepared by reacting bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcones of formula (Ill) with paratoluene sulfonic acid: wherein each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The reaction is carried out in the presence of an alcohol. Examples of the alcohol include ethanol, etc. The mechanism of the above reaction is as follows: wherein R1, R2, R3, R4, R5, R6, R7 and R8 are as described above. In particular, when bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcones react with paratoluene sulfonic acid, tetrahydropyran at both ends of the bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcones are removed. Then, hydrogen atoms in ethanol bond to the positions where tetrahydropyran has been removed to form bis(4,4′-hydroxy)chalcones of formula (II). Bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcones of formula (III) are prepared by reacting 4-(2-tetrahydro-2H-pyranoxy)acetophenones of formula (IV) with 4-(2-tetrahydro-2H-pyranoxy)benzaldehydes of formula (V): wherein each of R1, R2, R3 and R4 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group, wherein each of R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The reaction is carried out in the presence of an alkali metal salt. Examples of the alkali metal salt include sodium hydroxide, potassium hydroxide, etc. The mechanism of the above reaction is as follows: wherein R1, R2, R3, R4, R5, R6, R7 and R8 are as described above. In particular, 4-(2-tetrahydro-2H-pyranoxy)acetophenones of formula (IV) react with 4-(2-tetrahydro-2H-pyranoxy)benzaldehydes of formula (V) in the presence of an alkali metal salt. A condensation reaction between a ketone group and aldehyde group is carried out to form a bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcone of formula (III) that has a central enone group. The functional group that has an enone group and a phenyl group at both ends is referred to as a chalcone group. 4-(2-tetrahydro-2H-pyranoxy)acetophenones of formula (IV) are prepared by reacting 4-hydroxy acetophenones of formula (VI) with 3,4-dihydro-2H-pyran: wherein each of R1, R2, R3 and R4 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The mechanism of the above reaction is as follows: wherein R1, R2, R3 and R4 are as described above. In particular, 4-hydroxy acetophenones of formula (VI) react with 3,4-dihydro-2H-pyran to give 4-(2-tetrahydro-2H-pyranoxy)acetophenones of formula (IV). A carbon-carbon double bond in 3,4-dihydro-2H-pyran reacts with a hydroxyl group of 4-hydroxy acetophenones of formula (VI) to connect 3,4-dihydro-2H-pyran to 4-hydroxy acetophenones through an oxygen atom. 4-(2-tetrahydro-2H-pyranoxy)benzaldehydes of formula (V) are generated from the reaction of 4-hydroxy benzaldehyde of formula (VII) with 3,4-dihydro-2H-pyran: wherein each of R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The mechanism of the above reaction is as follows: wherein R5, R6, R7 and R8 are as described above. 4-hydroxy benzaldehydes of formula (VII) undergo the same reaction mechanism as described above with respect 3,4-dihydro-2H-pyran reacting with 4-hydroxy acetophenones of formula (VI) except that 4-(2-tetrahydro-2H-pyranoxy)benzaldehydes of formula (V) are formed. A total reaction scheme of the reactions is as follows: wherein n, R1, R2, R3, R4, R5, R6, R7 and R8 are as described above. Photoresist Composition A photoresist composition according to the present invention includes a curing agent, an organic solvent, and a compound represented by formula 1 as follows: wherein n is an integer from 1 to 10,000 and each of R1, R2, R3, R4, R5, R6, R7 and R8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The photoresist composition remnant is reduced when using the photoresist composition according to the present invention. The compound of formula (I) that has an epoxy group and a chalcone group is as described above, and is therefore not described in further detail here. The photoresist composition includes about 5 to about 35 parts by weight of the compound of formula (I), about 0.01 to about 5 parts by weight of the curing agent and about 60 to about 90 parts by weight of the organic solvent. When the photoresist composition includes more than 35 parts by weight of the compound of formula (I), mottle is regenerated in the liquid crystal display apparatus manufactured using the photoresist composition. When the photoresist composition includes less than 5 parts by weight of the compound, the adhering force of the photoresist composition is reduced, which is not preferable. Hence, the photoresist composition preferably includes about 5 to about 35 parts by weight of the compound of formula (I). The curing agent enables a radiation curing process and a heat curing process to be performed at the same time or independently. When the photoresist composition includes more than 5 parts by weight of the curing agent, the photoresist composition is prevented from fully curing which leads to a decrease in the adhesiveness of the photoresist composition. When the photoresist composition includes less than 0.1 parts by weight of the curing agent, curing speed decreases, which is not preferable. Thus, the photoresist composition preferably includes about 0.01 to about 5 parts by weight of the curing agent. Examples of the curing agent include an acrylated monomer such as dipentaerithritol hexaacrylate, trimethylolpropane trimethacrylate, etc. When the photoresist composition includes more than 90 parts by weight of the organic solvent, the adhering force of the photoresist composition is reduced, which is not preferable. When the photoresist composition includes less than 60 parts by weight of the organic solvent, mottle occurs in the liquid crystal display apparatus. Accordingly, the photoresist composition preferably includes about 60 to about 90 parts by weight of the organic solvent. Any organic solvent that has proper viscosity and volatility may be used as the organic solvent. Examples of the organic solvent include propylene glycol monomethyl ether acetate, ethyl ethoxy acetate, cyclohexanone, etc. When the photoresist composition including the compound of formula (I) is applied to a substrate and then exposed, a radical is generated from decomposition of the curing agent in the photoresist composition. The radical is cross-linked to the chalcone group in the compound of formula (I) to cure the photoresist composition. The photoresist composition may further include an acrylate resin. The acrylate resin prevents lifting between the photoresist composition and a substrate where the photoresist composition is applied, thereby enhancing the adhesiveness of the photoresist composition. The acrylate resin is preferably used in substantially the same quantity as the compound according to the present invention. The photoresist composition may further include a pigment. The pigment is dispersed in a solvent. The pigment is different from a dye in that the pigment is dissolved in a solvent. Examples of a red pigment include color index (CI) Pigment RED 177, CI Pigment RED 254, etc. Examples of a green pigment include CI Pigment GREEN 36, etc. Examples of a yellow pigment include CI Pigment YELLOW 138, CI Pigment YELLOW 139, CI Pigment YELLOW 150, etc. Examples of a blue pigment include CI Pigment BLUE 15:6, etc. Examples of a violet pigment include CI Pigment VIOLET 23, etc. The photoresist composition may further include a dispersant for dispersing the pigment in the photoresist composition. Generally, a mixture of the pigment and the dispersant is used. Examples of the mixture include products available from BYK-Chemie GmbH, Germany. The photoresist composition may further include a photo-initiator. After absorption of light, the photo-initiator generates a lot of radicals. The radicals initiate a reaction. Examples of the photo-initiator include benzyl dimethyl ketal, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(trichloromethyl)-s-triazine derivatives, etc. When the photoresist composition includes the pigment used for forming a color filter, the pigment adheres to the substrate having a black matrix by the radical that has been generated from the curing agent and cross-links to the chalcone group. Moreover, the surface of the photoresist composition is instantly cured in a photolithography process and the substrate is protected from impurities. The photoresist composition is then cured by heat. The adhesiveness of the photoresist composition increases due to the epoxy group of the compound of formula (I). Hence, the photoresist composition firmly adheres to the substrate having patterns. The chalcone group is connected to the main chain of the polymer compound of formula (I). The chalcone group may activate a cross-linking reaction and also serve as a binder. Thus, after a curing process, the surface of the photoresist composition becomes smooth and the photoresist composition remnant is not generated. However, when the chalcone group is attached to the side of the polymer compound, the chalcone group remains in the form of a thread after the curing process. Hence, the surface of the photoresist composition becomes rough and the photoresist composition remnant may be generated. The chalcone group as a polymer binder enhances an adhesive force between the substrate having black matrix patterns and the photoresist pattern during application of the photoresist composition. The chalcone group also maintains a uniform thickness of the photoresist composition. When manufacturing the color filter, preferably, the compound having the chalcone group is uniformly dispersed in the photoresist composition together with pigments and dispersants for the pigments. To be uniformly dispersed, the photoresist composition has different amounts of the compound having the chalcone group depending on the pigments employed. When the compound having the chalcone group is cured, a photoresist layer having a higher degree of cross-linking than that of a photoresist layer using a conventional acrylate resin is obtained. Thus, the curing process is completely carried out and there is no remnant. Therefore, the interaction between the photoresist layer and other materials is reduced. Because there is little remnant in the photoresist layer, the photoresist pattern is maintained in a good state in the successive process of forming a photoresist multilayer pattern. Consequently, the color filter using a compound having an epoxy group and a chalcone group according to the present invention has high color reproductivity and high brightness. The photoresist composition may be used, for example, in a liquid crystal display apparatus, e.g., organic electro-luminescent apparatus or inorganic electro-luminescent apparatus. The photoresist composition according to the present invention is prepared by dissolving the compound of formula (I) and the curing agent in an organic solvent and then dispersing the compound and the curing agent in the organic solvent. The compound of formula (I) may be used in the manufacture of a photoresist pattern used in a color filter. Hereinafter, the photoresist that includes a pigment and used in a color filter is referred to as a ‘color resist’. A color resist composition including the compound of formula (I), a curing agent and an organic solvent is applied to an underlying layer on a substrate to form a color resist layer. The color resist layer is then exposed and developed to form a color resist pattern. The process of forming the color resist pattern is performed by a conventional method of forming a photoresist pattern except that the process of stripping the photoresist composition is not performed. The underlying layer may be an insulation layer having a black matrix or an insulation layer having another color resist pattern. The process of forming the color resist pattern is depicted in FIGS. 1A and 1B. FIGS. 1A and 1B are cross-sectional views illustrating a process of forming the color resist pattern using a compound according to the exemplary embodiments of the present invention. Referring to FIG. 1A, a black matrix 305 is formed on a substrate 300. The substrate 300 includes glass, and the black matrix 305 includes chromium oxide. The black matrix 305 may include a single layer or a double layer of chromium oxide. A color resist composition includes a compound according to the present invention, a curing agent and an organic solvent. The color resist composition is applied to the black matrix 305 to form a color resist layer 310. The color resist layer 310 is baked at the temperature of about 80 to about 130° C. to evaporate the organic solvent. This process is referred to as a soft bake process. While the organic solvent is evaporated, the compound that has the epoxy group and the chalcone group in the color resist composition does not thermally decompose. Thus, the compound can be cured by radiation and heat. After the organic solvent is evaporated, the color resist layer 310 has a thickness of about less than 2 μm. A mask 350 having patterns is disposed over the color resist layer 310. An ultraviolet (UV) ray 370 is irradiated onto the color resist layer 310 through the mask 350. A portion of the color resist layer 310 is exposed to the ultraviolet ray 370 upon the pattern of the mask 350. The exposed portion of the color resist layer 310a undergoes a photo reaction to be soluble in a subsequent developing process. The substrate 300 having the exposed color resist layer 310a is dipped into an alkaline developing solution. Then, the exposed color resist layer 310a is dissolved in the developing solution. Examples of the alkaline developing solution include hydroxides of alkali metals, ammonium hydroxides, tetramethyl ammonium hydroxides, etc. The substrate 300 is then taken out of the developing solution and heated to a temperature of about 90 to about 140° C. to enhance adhesion and chemical resistance of the color resist layer 310. This process is referred to as a hard bake process. The hard bake process is performed under a softening temperature of the color resist layer 310. If the hard bake process is carried out at or over the softening temperature of the color resist layer 310, the color resist layer 310 may collapse. Through this hard bake process, a color resist pattern 315 is formed. When forming color filters, after forming the color resist pattern 315, another color resist composition may be applied to the substrate, exposed and then developed to form another color resist pattern on the substrate and a color resist multilayer pattern on the black matrix. This procedure is repeated to form an overall color resist pattern. Hereinafter, the present invention is described in detail with reference to the following examples. The examples are given solely for the purpose of illustration and are not to be construed as limitations of the present invention, as many variations thereof are possible without departing from the spirit and scope of the invention. EXAMPLE 1 Preparation of a Compound Having the Epoxy Group and the Chalcone Group (i) Synthesis of 4-(2-tetrahydro-2H-pyranoxy)acetophenone and 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde 5 g (0.0367 mol) of 4-hydroxy acetophenone was dissolved in 150 ml of chloroform. 3.09 g (0.0367 mol) of 3,4-dihydro-2H-pyran and 930 mg (0.0037 mol) of pyridium paratoluene sulfonic ester as a catalyst were added and then the reaction mixture was stirred at room temperature for about 8 hours. The reaction mixture was extracted with water and chloroform and precipitated using hexane at a temperature of 0 to about 5° C. and then dried. Approximately 6.48 g (0.0294 mol) of 4-(2-tetrahydro-2H-pyranoxy)acetophenone was obtained. The yield of the reaction was about 80%. 5 g (0.0409 mol) of 4-hydroxy benzaldehyde was dissolved in 150 ml of chloroform. 3.44 g (0.0409 mol) of 3,4-dihydro-2H-pyran and 1.03 g (0.0041 mol) pyridium paratoluene sulfonic ester as a catalyst were added while stirring. The reaction mixture was then stirred at room temperature for about 8 hours. The reaction mixture was extracted using water and chloroform and precipitated using hexane at a temperature of 0 to about 5° C. and then dried. Approximately 7.17 g (0.0348 mol) of 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde was obtained. The yield of the reaction was about 85%. (ii) Synthesis of bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcone 10 g (0.048 mol) of 4-(2-tetrahydro-2H-pyranoxy)acetophenone and 10.57 g (0.048 mol) of 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde were dissolved in 200 ml of ethanol. An aqueous sodium hydroxide solution was slowly added to the reaction mixture at room temperature. A thin layer chromatography was conducted every hour to check the progress of the reaction. After 10 hours, the reaction was terminated. The reaction compound was extracted with chloroform as an organic solvent and then precipitated. Approximately 14.71 g (0.036 mol) bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcone was obtained. The yield of the reaction was about 75%. (iii) Synthesis of bis(4,4′-hydroxy)chalcone 10 g (0.024 mol) of bis[4,4′-(2,2′-tetrahydro-2H-pyranoxy)]chalcone was dissolved in 200 ml of ethanol at the temperature of about 50 to about 60° C. while stirring for 30 minutes. Then, 603 mg (0.0024 mol) of paratoluene sulfonic acid was added, and the reaction was maintained for about 4 hours. The product was precipitated using tetrahydrofuran and hexane. Approximately 5.19 g (0.0216 mol) of bis(4,4′-hydroxy)chalcone was obtained. The yield of the reaction was about 90%. (iv) Synthesis of a Compound Having an Epoxy Group and a Chalcone Group 5 g (0.0208 mol) of bis(4,4′-hydroxy)chalcone and 385 g (4.16 mol) of epichlorohydrin were mixed at about 40° C. An aqueous sodium hydroxide solution was slowly added to the reaction mixture. The reaction mixture was stirred for about 12 hours at about 40° C., extracted with water and toluene and then dried to obtain approximately 11.4 g of an aqueous compound having an epoxy group and a chalcone group. The compound had a weight average molecular weight of about 900. (v) Determination of the Compound 1H-NMR (300 MHz, CDCl3) spectrum of the compound was obtained. FIG. 2 is an NMR spectrum of the compound obtained in Example 1 having the epoxy group and the chalcone group. Hydrogen atoms of the epoxy group({circle over (1)}and {circle over (2)}), hydrogen atom from epichlorohydrin({circle over (3)}), hydrogen atom of the enone group({circle over (4)}) are shown in the 1H-NMR spectrum of FIG. 2. It is clear that the compound obtained in Example 1 has an epoxy group and a chalcone group. The infrared spectra of the compound were obtained. FIG. 3A represents infrared spectra of the compound obtained in Example 1 with respect to time. FIG. 3B represents enlarged infrared spectra of FIG. 3A having a wave number of 1500 to 1700 cm. In infrared spectra, the light source is an ultraviolet ray having a wavelength of about 365 nm, and the intensity of the light is 12.73 mV/cm2. Referring to FIGS. 3A and 3B, an absorption band is observed near the wave number of 914 cm−1 that corresponds to an epoxy ring. Another absorption band near the wave number of 1600 cm−1 corresponds to a carbon-carbon double bond in the chalcone group. Meanwhile, when the ultraviolet ray is irradiated onto the chalcone group, the carbon-carbon double bond in the chalcone group reacts with another carbon-carbon double bond in another chalcone group to form a carbon-carbon single bond. The carbon-carbon double bond disappears with time. Thus, by analyzing the infrared spectrum representing the carbon-carbon double bond, the photochemical reactivity of the compound may be confirmed. In FIGS. 3A and 3B, spectrum ‘A’ corresponds to the infrared spectrum right after the radiation of the ultraviolet ray. Spectrum ‘B’ corresponds to the infrared spectrum 10 minutes after the radiation. Spectrum ‘C’ corresponds to the infrared spectrum 30 minutes after the radiation, and spectrum ‘D’ corresponds to the infrared spectrum 60 minutes after the radiation. Referring to FIG. 3B, it can be noted that the peak near the wave number of 1600 cm−1 represents that the carbon-carbon double bond has been reduced 60 minutes after the radiation. Thus, it is clear the chalcone group in the compound obtained in Example 1 reacts with light. It can also be noted from the spectra that the compound obtained in Example 1 has both a chalcone group having a radiation curing property and an epoxy group having a heat curing property. EXAMPLE 2 Synthesis of Photoresist Composition 63.5 g of the compound obtained in Example 1, 63.5 g of acrylate resin, 2 g of dipentaerithritol hexaacrylate as a curing agent, 1 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photo-initiator and 225 g of a mixture of a green pigment and a dispersant for the pigment were added to 145 g of propylene glycol monomethyl ether acetate. The reaction mixture was stirred at room temperature for about 3 hours and then filtered using a filter having a pore size of 2.5 μm to obtain about 410 g of a green color resist composition. COMPARATIVE EXAMPLE 1 Synthesis of a Conventional Photoresist Composition 127 g of acrylate resin, 2 g of dipentaerithritol hexaacrylate as a curing agent, 1 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photo-initiator and 225 g of a mixture of a green pigment and a dispersant for the pigment were added to 145 g of propylene glycol monomethyl ether acetate. The reaction mixture was stirred at room temperature for about 3 hours to obtain about 390 g of a green color resist composition. Experiment 1: Color Reproductivity and Brightness Red and blue color resist compositions were synthesized to be used with the green color resist composition obtained in Example 2. Color reproductivity and brightness of the photoresist composition according to an exemplary embodiment of the present invention were tested. (i) Synthesis of Red Color Resist Composition 100 g of acrylate resin, 1 g of dipentaerithritol hexaacrylate as a curing agent, 1 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photo-initiator and 200 g of a mixture of a red pigment and a dispersant for the pigment were added to 180 g of propylene glycol monomethyl ether acetate. Then, the reaction mixture was stirred at room temperature for about 3 hours. The reaction mixture was filtered using a filter having a pore size of 2.5 μm to obtain about 388 g of a red color resist composition. (ii) Synthesis of Blue Color Resist Composition 112.5 g of acrylate resin, 1.5 g of dipentaerithritol hexaacrylate as a curing agent, 1 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photo-initiator and 210 g of a mixture of a blue pigment and a dispersant for the pigment were added to 175 g of propylene glycol monomethyl ether acetate. Then, the reaction mixture was stirred at room temperature for about 3 hours. The reaction mixture was filtered using a filter having a pore size of 2.5 μm to obtain about 395 g of a blue color resist composition. The red color resist composition obtained above, green color resist composition obtained in Example 2 and blue color resist composition obtained above were sequentially applied to a silicon substrate, and the substrate was baked at about 100° C. by a soft baking process. An ultraviolet ray was irradiated onto the substrate through a mask having patterns. The exposed substrate was dipped into an alkaline developing solution, and then the substrate was heat treated to obtain a color resist pattern on the substrate. The color resist pattern was formed of a monolayer or multilayer. The color reproductivity and brightness of the color filter using the color resist pattern was determined. The properties including the brightness are shown in Table 1 below. TABLE 1 Color coordinate (x, y) and brightness (Y) Color resist pattern x y Y red color resist monolayer pattern 0.6464 0.3420 21.90 green color resist monolayer pattern 0.3012 0.5720 61.81 blue color resist monolayer pattern 0.1380 0.1280 16.37 red color resist multilayer pattern 0.6397 0.3426 23.03 green color resist multilayer pattern 0.3006 0.5699 61.90 blue color resist multilayer pattern 0.1383 0.1302 16.63 As shown in Table 1, the x color coordinate of the green color resist monolayer pattern is 0.3012 and the x color coordinate of the green multilayer pattern is 0.3006. The difference between them is insignificant. Thus, it can be noted that the color reproductivity of the green color resist multilayer pattern is excellent. The y color coordinate of the blue color resist monolayer pattern is 0.1280, and the y color coordinate of blue color resist multilayer pattern is 0.1302. The difference between them is insignificant. Thus, it can be noted that the color reproductivity of the blue color resist multilayer pattern is excellent. Y represents brightness of a color filter. As shown in Table 1, the Y values in the multilayers are greater than the Y values than in the monolayers, thereby showing the brightness of the color resist in the multilayer patterns has not been reduced. COMPARATIVE EXAMPLE 1 The procedure of Experiment 1 was repeated except that a conventional green color resist composition obtained in Comparative Example 1 was used to determine the color reproductivity and brightness. The color characteristics of monolayers and multilayers are shown in FIG. 4. The properties including brightness are shown in Table 2. FIG. 4 is a graph illustrating color characteristics of monolayer and multilayer patterns using the conventional photoresist composition of Comparative Example 1. As shown in FIG. 4, color coordinates of the green and blue color resist multilayer patterns are moved from those of monolayer patterns. This indicates that during application of another color resist composition on a color resist monolayer pattern, the color resist composition that is supposed to be removed remains causing movement of the color coordinates. Thus, the remnant ascribes to the incomplete curing of the acrylate resin. TABLE 2 Color coordinate (x, y) and brightness (Y) Color resist pattern x Y Y red color resist monolayer pattern 0.6357 0.3424 23.73 green color resist monolayer pattern 0.3104 0.5562 66.75 blue color resist monolayer pattern 0.1437 0.1459 20.34 red color resist multilayer pattern 0.6345 0.3423 23.54 green color resist multilayer pattern 0.2862 0.5677 57.45 blue color resist multilayer pattern 0.1394 0.1298 16.66 As shown in Table 2, the x color coordinate of a green color resist monolayer pattern is 0.3104 and the x color coordinate of a green color resist multilayer pattern is 0.2862. The difference between the x color coordinates above is greater than that of Experiment 1. Hence, the color reproductivity of the green color resist multilayer pattern is not satisfactory. The y color coordinate of the blue color resist monolayer pattern is 0.1459, and the y color coordinate of the blue color resist multilayer pattern is 0.1298. The difference between the y color coordinates above is greater than that of Experiment 1. Thus, color reproductivity of the blue color multilayer pattern is not satisfactory. When comparing the color coordinates of each of the red, green and blue color resist monolayer patterns with those of multilayer patterns, color coordinates of green and blue color resist multilayer patterns are significantly moved representing a reduction of color reproductivity. Y, which represents brightness, of the multilayer patterns is significantly reduced as compared to the Y of the monolayer patterns. Thus, the color resist multilayer pattern using the conventional color resist composition has reduced brightness. Experiment 2: Shape and Surface Roughness of Pattern A color resist pattern was formed using the color resist composition obtained in Example 1. The shape and surface roughness of the color resist pattern was observed by a scanning electron microscope (SEM). FIG. 5 is an electron microscope photograph illustrating the shape of the color resist pattern obtained in Experiment 2. FIG. 6 is an electron microscope photograph illustrating the surface condition of a portion of the color resist pattern obtained in Experiment 2. Referring to FIG. 5, a color resist monolayer pattern is adjacent to a color resist multilayer pattern. The portion where the color resist monolayer pattern is adjacent to the color resist multilayer pattern is smooth. Moreover, each of the color resist monolayer and multilayer patterns is not collapsed or cracked. Referring to FIG. 6, the surface of the color resist pattern is smooth. The surface roughness of the color resist pattern is 52 Å. The color resist pattern using a compound according to the present invention shows excellent color reproductivity and brightness after forming a color resist multilayer pattern. COMPARATIVE EXAMPLE 2 A color resist pattern was formed using a conventional color resist composition including the acrylate resin. The shape and surface roughness of the color resist pattern was observed by a scanning electron microscope (SEM). FIG. 7 is an electron microscope photograph illustrating the shape of the color resist pattern obtained in Comparative Experiment 2. FIG. 8 is an electron microscope photograph illustrating the surface condition of a portion of the color resist pattern obtained in Comparative Experiment 2. Referring to FIG. 7, a color resist monolayer pattern is adjacent to a color resist multilayer pattern. The portion where the color resist monolayer pattern is adjacent to the color resist multilayer pattern is rough. Moreover, the color resist multilayer pattern is partially collapsed. Referring to FIG. 8, the surface of the color resist pattern is rough. The surface roughness of the color resist pattern is 210 Å, which is greater than that of Experiment 2. Further, the color resist pattern using the acrylate resin has reduced color reproductivity and brightness. A photoresist composition including a compound according to the present invention has the following advantages. The photoresist composition including a compound according to the present invention has substantially no remnant. Thus, the photoresist composition may be used in a large display apparatus or a fine pitch display apparatus. Further, the photoresist composition including a compound of the present invention substantially prevents the formation of remnant in a color resist pattern, changes of color coordinates of a color resist pattern and the reduction of brightness during the formation of a multilayer color pattern, thereby forming a color filter having improved color reproductivity and brightness. Having described the exemplary embodiments of the present invention and its advantages, it is noted that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the present invention as defined by appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Technical Field The present invention relates, generally, to a compound having an epoxy group and a chalcone group, a method of preparing the same, and a photoresist composition comprising the same. More particularly, the present invention relates to a compound having an epoxy group that has a heat curing property and a chalcone group that has a radiation curing property, a method of preparing the same, and a photoresist composition comprising the same. 2. Discussion of the Related Art Liquid crystal display apparatuses (LCDs) are widely used in various devices, such as cellular phones, billboards, computer monitors, televisions, etc., because of the many advantages LCDs provide. These advantages include much lower power consumption than other display devices and being thinner and lighter than cathode ray tubes. Generally, to display an image, an LCD apparatus includes an LCD panel and a backlight assembly for supplying light to the LCD panel. The LCD panel includes liquid crystal interposed between two glass substrates. Transmittance of light through the LCD panel is adjusted by controlling and varying the voltage applied to the pixels of the LCD panel. To display color, an LCD apparatus can use three subpixels with color filters, e.g., a red filter, a green filter and a blue filter, to create each color pixel. The transmitted light that passes through the color filters is additively mixed to display a full color screen. For high color reproductivity and brightness close to natural color, the liquid crystal display apparatus needs to have high resolution and light efficiency, and the color filter must be precisely patterned. Photoresist compositions are used for patterning color filters. A conventional photoresist composition includes an acrylate resin, a curing agent and an organic solvent. The photoresist composition may further include a pigment when used for manufacturing a color filter. The acrylate resin has a radiation curing property. The acrylate resin provides a photo cross-linking reaction during an exposure process and then acts as a binder between a pattern and the pigment. In the conventional photoresist compositions, the acrylate resin is usually not completely cured. Hence, a molecular interaction occurs between the surface of a photoresist pattern and a subsequently applied photoresist composition or dispersant for the pigment, thereby generating a photoresist composition remnant. The remnant deteriorates the color characteristics and reduces brightness of the color filter. Moreover, the remnant may cause failures in a junction to a pixel electrode. In particular, when a photoresist multilayer pattern is formed, a color coordinate may be moved, thereby reducing the brightness of the color filter. Therefore, a need exists for a photoresist composition that prevents the formation of a remnant in a photoresist pattern used in forming a color filter to provide a color filter having improved color reproductivity and brightness. | <SOH> SUMMARY OF THE INVENTION <EOH>It is a feature of the present invention to provide a compound having an epoxy group that has a heat curing property and a chalcone group that has a radiation curing property. It is another feature of the present invention to provide a method of preparing the compound. It is still another feature of the present invention to provide a photoresist composition including the composition. Exemplary Embodiments of the present invention are directed toward a composition comprising an epoxy group and a chalcone group. The compound comprising an epoxy group and a chalcone group is represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. In addition, the compound has a weight average molecular weight of about 800 to about 20,000. According to another exemplary embodiment, a process for preparing a compound including an epoxy group and a chalcone group is provided. The process comprises reacting bis(4-4′-hydroxy)chalcone with epichorohydrin in the presence of an alkali metal salt to synthesize a compound represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group. The process may also include reacting bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone with a paratoluene sulfonic acid in the presence of an alcohol to synthesize the bis(4-4′-hydroxy)chalcone. In addition, the process may include reacting 4-(2-tetrahydro-2H-pyranoxy)acetohenone with 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde in the presence of an alkali metal salt to synthesize the bis[4,4′-(2-2′-tetrahydro-2H-pyranoxy)]chalcone. Further, the process may include reacting 4-hydroxy benzaldehyde with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)benzaldehyde. Furthermore, the process may include reacting 4-hydroxy acetophenone with 3,4 dihydro-2H-pyran to synthesize the 4-(2-tetrahydro-2H-pyranoxy)acetohenone. According to yet another exemplary embodiment, a resist composition including a compound having an epoxy group and a chalcone group is provided. The resist composition comprising a curing agent, an organic solvent, and a compound comprising an epoxy group and a chalcone group represented by the following formula: wherein n is an integer from 1 to 10,000 and each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 is selected from a group consisting of a hydrogen atom, alkyl group, alkoxy group, halogen atom and nitro group; In addition, the resist composition may include about 5 to about 35 parts by weight of the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. Further, the resist composition may include an acrylate resin. The resist composition may also include about 5 to about 35 parts by weight of a combination of the acrylate resin and the compound, about 0.01 to about 5 parts by weight of the curing agent, and about 60 to about 90 by weight of the organic solvent. According to still yet another exemplary embodiment, a method for forming a color resist pattern is provided. The method for forming a color resist pattern comprising the steps of applying a layer of a first color resist composition to a black matrix on a substrate to form a first color resist layer, wherein the first color resist composition includes a compound having a chalcone and an epoxy group, a curing agent, an organic solvent, and a pigment, baking the first color resist layer, wherein the organic solvent is evaporated, disposing a first mask having patterns over the first color resist layer, exposing a portion of the first color resist layer through the first mask, developing the exposed first color resist layer, wherein the exposed portion of the first color resist is dissolved in a developing solution, and heating the substrate with the developed first color resist layer, thereby forming a first color resist pattern. These and other exemplary embodiments, features, aspects, and advantages of the present invention will be described in more detail and become more apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. | 20040324 | 20060627 | 20050428 | 71953.0 | 0 | HAMILTON, CYNTHIA | COMPOUND HAVING AN EPOXY GROUP AND A CHALCONE GROUP, METHOD OF PREPARING THE SAME, AND PHOTORESIST COMPOSITION COMPRISING THE SAME | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,870 | ACCEPTED | Algorithms and methods for determining laser beam process direction position errors from data stored on a printhead | Systems and methods are provided for characterizing laser beam process direction position errors in an electrophotographic device. Once the process direction position errors of a given beam laser beam system have been characterized, an image is adjusted or warped prior to being processed by the laser beam system to compensate for laser beam process direction position errors, e.g., bow and skew. | 1. A method of electronically compensating for process direction position errors of a laser beam in an electrophotographic device comprising: reading a plurality of laser beam position measurements; constructing a laser beam scan path model from said laser beam position measurements that generally models a scan path of said laser; converting said laser beam scan path model into a Pel profile that characterizes process direction position errors of Pels written by said laser; and warping a bitmap image based upon said Pel profile prior to writing said bitmap image by said laser beam. 2. The method according to claim 1, wherein said laser beam scan path model is rotated so as to form a mirror image of said scan path of said laser beam. 3. The method according to claim 1, further comprising compensating said laser beam scan path model based upon registration data entered into said device. 4. The method according to claim 3, wherein said registration data comprises skew correction information and said laser beam scan path model is compensated for skew comprising: locating the position of the first writable Pel along said laser beam scan path model; and rotating said laser beam scan path model about said first writable Pel based upon said skew correction information. 5. The method according to claim 1, further comprising: converting said laser beam scan path model into a Pel model that corresponds Pel locations to associated locations of said scan path model, wherein said Pel profile is constructed from said Pel model. 6. The method according to claim 1, wherein said warping of said bitmap image data is performed by a bow processor in a controller of said electrophotographic device, and said warping of said bitmap image data based upon said Pel profile comprises converting said Pel profile into a bow profile, which translates said Pel profile into a format suitable for processing by said bow processor. 7. The method according to claim 1, wherein said plurality of laser beam position measurements comprise measurements taken at a plurality of test points. 8. The method according to claim 7, wherein said plurality of test points are read from a memory device on a printhead of said device. 9. The method according to claim 7, wherein each test point comprises a scan direction measurement, a process direction measurement, and a measurement corresponding to an angle of a rotating polygonal mirror in a corresponding printhead. 10. The method according to claim 9, wherein said scan direction measurements and said process direction measurements are taken relative to a predetermined, local coordinate system. 11. The method according to claim 10, wherein said laser beam scan path model is constructed by converting for each test point, the corresponding measurement in said scan direction and the corresponding measurement in said process direction, to a coordinate system taken with respect to a known point on a printhead of said device. 12. A method of electronically compensating for process direction position errors of a laser beam in an electrophotographic device comprising: constructing a Pel profile that characterizes process direction position errors of Pels written by said laser; and warping a bitmap image based upon said Pel profile prior to writing said bitmap image by said laser beam, wherein said Pel profile is constructed by: constructing a model of a scan path of said laser beam; dividing said model into a plurality of Pel locations; and determining for each Pel location, a corresponding offset in a process direction which is transverse to a scan direction of said laser beam, based upon said model. 13. The method according to claim 12, wherein each Pel location is encoded using at least two bits that define whether that Pel location defines a jump up, a jump down, or no jump. 14. The method according to claim 13, wherein each jump comprises one Pel in said process direction. 15. The method according to claim 12, wherein said offset for each Pel location is determined comprising: dividing said model into a plurality of sections, each section comprising a plurality of Pel locations including a start Pel location which is the first Pel location in a corresponding one of said sections, and a stop Pel location which is the last Pel location in said corresponding one of said sections, and for each section: determining a number of Pel locations in said section; determining a process direction offset for each of said start and stop Pel locations; determining a number of Pel jumps between said process direction offsets of said start Pel location and said stop Pel location; and distributing said number of Pel jumps across said Pel locations in said section. 16. The method according to claim 15, wherein the process direction offset of each Pel location is encoded into a bit profile that encodes each Pel location process direction offset as a function of the process direction offset of an adjacent Pel location. 17. The method according to claim 16, wherein each process direction offset is encoded to represent a select one of no change in process direction position from an adjacent Pel location, a jump up one Pel location in the process direction relative to said adjacent Pel, or a jump down one Pel location in the process direction relative to said adjacent Pel. 18. The method according to claim 15, wherein said number of Pel jumps are distributed generally evenly across said section. 19. A method of electronically compensating for process direction position errors of a laser beam in a color electrophotographic device comprising: constructing a Pel profile that characterizes process direction position errors of Pels written by a corresponding laser for each of four color image planes; and warping an image by: deconstructing said image into four bitmaps, each bitmap corresponding to a select one of said four color image planes; and warping each bitmap based upon a corresponding one of said Pel profiles prior to writing said bitmap by said corresponding laser beam, wherein each Pel profile is constructed by: constructing a model of a scan path of said corresponding laser beam; dividing said model into a plurality of Pel locations; and determining for each Pel location, a corresponding offset in a process direction which is transverse to a scan direction of said laser beam, based upon said model. | CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to U.S. Patent Application Serial No. ______, Attorney Docket 2002-0711, entitled “Memory Device On Optical Scanner And Apparatus And Method For Storing Characterizing Information On The Memory Device”; U.S. patent application Ser. No.______, Attorney Docket 2003-0848, entitled “Systems For Performing Laser Beam Linearity Correction And Algorithms And Methods For Generating Linearity Correction Tables From Data Stored In An Optical Scanner”; and U.S. patent application Ser. No.______, Attorney Docket 2003-0839, entitled “Electronic Systems And Methods For Reducing Laser Beam Process Direction Position Errors”; each of which is filed currently herewith and hereby incorporated by reference herein. BACKGROUND OF THE INVENTION The present invention relates to an electrophotographic imaging apparatus, and more particularly to systems and methods for characterizing laser beam process direction position errors. In electrophotography, a latent image is created on the surface of an electrostatically charged photoconductive drum by exposing select portions of the drum surface to laser light. Essentially, the density of the electrostatic charge on the surface of the drum is altered in areas exposed to a laser beam relative to those areas unexposed to the laser beam. The latent electrostatic image thus created is developed into a visible image by exposing the surface of the drum to toner, which contains pigment components and thermoplastic components. When so exposed, the toner is attracted to the drum surface in a manner that corresponds to the electrostatic density altered by the laser beam. Subsequently, a print medium such as paper is given an electrostatic charge opposite that of the toner and is pressed against the drum surface. As the medium passes the drum, the toner is pulled onto the surface thereof in a pattern corresponding to the latent image written to the drum surface. The medium then passes through a fuser that applies heat and pressure thereto. The heat causes constituents including the thermoplastic components of the toner to flow into the interstices between the fibers of the medium and the fuser pressure promotes settling of the toner constituents in these voids. As the toner is cooled, it solidifies and adheres the image to the medium. In order to produce an accurate representation of an image to be printed, it is necessary for the laser to write to the drum in a scan direction, which is defined by a straight line that is perpendicular to the direction of movement of the print media relative to the drum (the process direction). However, a number of optical elements including lenses and mirrors are typically required in the apparatus, including the printhead, to direct the laser beam towards the drum. Unavoidable imprecision in the shape and mounting of these optical elements with respect to the laser beam and/or drum can introduce process direction errors in the path of travel of the laser beam when writing across a scan line. It is also possible that a scan line written to the drum is not perpendicular to the movement of the print media due to laser misalignment and/or media misregistration. Under these conditions, there may be a skew associated with the printed image. The prior art has attempted to correct for laser beam process direction position errors by incorporating carefully manufactured optics that are precisely aligned. However, the increased precision required by each optical element adds significantly to its cost. Even with precisely manufactured and aligned optics, the degree to which laser beam process direction position errors may be corrected is limited by several factors, including component tolerances. Moreover, distortion of the laser beam optical scan path can occur even in a precisely aligned system due to component aging and/or operational influences such as temperature changes. SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of the prior art by providing systems and methods for characterizing laser beam process direction position errors in an electrophotographic device. Once the process direction position errors of a given laser beam have been characterized, bitmap image data may be adjusted or warped based upon the characterization in a manner that generally compensates therefore. According to an embodiment of the present invention, a table is stored in a memory device for each laser beam of an electrophotographic device. The table stores a plurality of data points that define measurements of the process direction position of the laser beam at several locations along a scan line. A laser scan path model of the laser beam is constructed from the plurality of data points to characterize the laser beam process direction position errors across the scan line. According to another embodiment of the present invention, a table is stored in a memory device for each laser beam of an electrophotographic device. The table stores a plurality of data points that define measurements of the process direction position of the laser beam at several locations along a scan line. A laser scan path model of the laser beam is constructed from the plurality of data points, and a pel profile is constructed from the laser scan path model. The pel profile is constructed in such a manner that it can be updated to account for changes in scan beam process direction errors due to registration and/or media misalignment corrections entered into the device, such as may be entered during a setup or calibration procedure. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The following detailed description of the preferred embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals, and in which: FIG. 1 is a block diagram of a controller for an electrophotographic device according to an embodiment of the present invention; FIG. 2 is a schematic view of a laser scanning system from the perspective of a printhead looking onto a print medium; FIG. 3 is a schematic representation of the relationship between the four lasers in the printhead, and the rotating polygonal mirror; FIG. 4 is a flow chart for creating a bow profile that characterizes process direction position errors of a corresponding laser beam as it traverses across its scan path; FIG. 5 is a flow chart for creating a bow profile that characterizes process direction position errors of a corresponding laser beam as it traverses across its scan path; FIG. 6 is a schematic illustration of a laser beam profile with respect to a photoconductive drum axis; FIG. 7 is a schematic illustration of the laser beam profile of FIG. 6 rotated about the photoconductive drum axis; FIG. 8A is a schematic illustration of a method for determining laser beam skew showing rotation of the last writable Pel relative to the first writable Pel; FIG. 8B is a schematic illustration of the method for determining laser beam skew illustrated in FIG. 8A showing additional test points; FIG. 9 is a flow chart illustrating a method for converting a scan path model into a Pel profile according to the present invention, and FIG. 10 is a chart illustrating the spacing of jumps between start and stop Pels. DETAILED DESCRIPTION OF THE INVENTION In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. General System Overview FIG. 1 illustrates the main components of a system 10 for characterizing and correcting laser beam process direction position errors according to the present invention. The system 10 includes generally, a controller 12 and a printhead 14. The controller 12 includes the electronics and logic necessary for performing electrophotographic imaging including the performance of operations necessary to characterize laser beam process direction position errors as set out in greater detail herein. As shown, the controller 12 includes system memory 16, a microprocessor 18, a bow processor 20 and one or more video processors 22. The printhead 14 includes a laser system 24, an optical system 26 and a memory device 28. If implemented in a color device, the system 10 may include four video processors 22, one video processor 22 for each of the cyan, yellow, magenta and black (CYMK) image planes. Each video processor 22 may have associated therewith, a corresponding laser in the laser system 24 of the printhead 14. Prior to initiating a printing operation, the microprocessor 18 reads a plurality of laser beam position measurements 30 from the memory device 28 on the printhead 14 and derives therefrom, a laser beam scan path model 32 for each laser beam in the laser system 24. Each laser beam scan path model 32 generally describes or models the scan path of the corresponding laser beam as it moves across a corresponding photoconductive drum. The microprocessor 18 then converts each laser beam scan path model 32 into a corresponding Pel model 33 that represents the associated laser beam scan path data in terms of Pel locations and process direction offsets. Each Pel model 33 is expanded into a Pel profile 34 that characterizes process direction position offsets for each Pel location along an associated laser beam scan path. Each Pel profile 34 is then used to derive a corresponding bow profile 35. The bow profile 35 includes a representation of the data in the Pel profile 34 in a format suitable for processing by the bow processor 20. Basically, the process direction position offset of each Pel location defines a measure of laser beam error that if uncorrected, would result in distortion in the output of an image written by the corresponding laser beam. Process direction position errors of the lasers in the laser system 24 include, for example, bowed and/or skewed scan lines formed on a corresponding photoconductive drum and can be caused by a number of factors including unavoidable imprecision in the shape and mounting of components in the optical system 26, laser misalignment and/or media misregistration. Briefly, an image to be printed is temporarily stored in the system memory 16. For color printing, the image is deconstructed into four bitmaps corresponding to the cyan, yellow, magenta and black (CYMK) image planes. The microprocessor 18 then initiates a printing operation whereby each color image plane bitmap is communicated to the bow processor 20. The bow processor 20 pre-warps the bitmap image data according to the associated bow profile 35 before the image data is converted into an appropriate video signal by the corresponding video processor 22. The bow profile 35 essentially instructs the bow processor 20 how to warp the image data in a manner that generally compensates for the process direction position errors of written Pels inherent in the corresponding laser beam scan path, which reduces the distortion evident in the output image. The pre-warped image data may be stored in an appropriate memory location, such as in the system memory 16, before being communicated to the associated video processor 22, which converts the pre-warped image data into a video signal suitable for writing by the corresponding laser in the printhead 14. Factors affecting process direction position errors are discussed in greater detail in U.S. patent application Ser. No.______, Attorney Docket 2003-0839, entitled “Electronic Systems And Methods For Reducing Laser Beam Process Direction Position Errors”, which is already incorporated by reference herein. For example, the bow processor 20 discussed herein corresponds to the bow system and corresponding bow processor discussed therein. Likewise, the algorithms and methods for determining laser beam process direction position errors, which are set out in the present application, may be applied to U.S. patent application Ser. No.______, Attorney Docket 2003-0839. For example, the bow profile 35 herein corresponds to the bow profile disclosed in that application. Laser Beam Scan Path Test Points In order to ultimately derive the bow profile 35, the microprocessor 18 first determines a measure of the process direction position errors for each laser beam based upon the laser beam measurements 30, which are stored on a memory device 28 of the printhead 14. Referring to FIG. 2, a schematic representation of a laser scanning system 100 is illustrated from the perspective of the printhead 14 looking onto a print medium. Typically, each laser beam of the printhead 14 writes to a corresponding photoconductive drum. However, for purposes of clarifying the principles of the current embodiment of the present invention, FIG. 2 assumes that each laser writes directly to a print medium (indicated by the dashed box 102) instead of its corresponding photoconductive drum. The print medium 102 is assumed to move up the page in a process direction, as illustrated by the directional arrow 104. Notably, the width of the print medium 102, e.g., a typical sheet of letter-sized paper, is less than the maximum writeable area of the corresponding laser beams as indicated by the dashed box 106. The ideal scan path for each laser beam is a straight line scan path that is transverse to the process direction 104, thus across the page as shown. However, each laser beam is likely to exhibit process direction position errors. In FIG. 2, most of the illustrated errors are generally bow like in shape. However, it is contemplated that a scan line path can be skewed as well. As such, the scan path for each laser beam is encompassed by a scan plane as illustrated, which represents an area bounding each laser beam scan path. That is, a cyan scan plane 108 represents an area that bounds the scan path of the cyan laser beam. A magenta scan plane 110 represents an area that bounds the scan path of the magenta laser beam. A yellow scan plane 112 represents an area that bounds the scan path of the yellow laser beam. And correspondingly, a black scan plane 114 represents an area that bounds the scan path of the black laser beam. To frame the laser beam position measurements into a meaningful context for processing, each scan plane 108, 110, 112, 114 is associated with a corresponding local beam position origin 116, 118, 120, 122. As shown, a cyan beam position origin 116 is arbitrarily positioned with respect to the cyan scan plane 108. A magenta beam position origin 118 is arbitrarily positioned with respect to the magenta scan plane 110. A yellow beam position origin 120 is positioned with respect to the yellow scan plane 112, and correspondingly, a black position origin 122 is arbitrarily positioned with respect to the black scan plane 114. The beam position origins 116, 118, 120, 122 are provided for convenience and allow scan path measurements taken in each corresponding scan plane 108, 110, 112, 114 to be referenced relative to a local coordinate system. It may be convenient to select a position for each of the beam position origins 116, 118, 120, 122 in a manner that minimizes or eliminates the need to store and manipulate negative numbers. For example, by selecting the beam position origin 116, 118, 120, 122 to be located before the first test point measured relative to the scan direction, i.e., the direction of travel of the corresponding laser beam, all of the scan direction measurements (X-axis measurements) will be positive. Correspondingly, by setting the beam position origin 116, 118, 120, 122 at or below the lowest expected test point with respect to the process direction 104 of a given scan plane 108, 110, 112, 114, process direction measurements (Y-axis measurements) will be positive. As shown, the process direction 104 is the same for all of the scan planes 108, 110, 112, 114. However, the cyan and magenta laser beams traverse generally in a first scan direction 124, illustrated as traversing across the page from the right to the left. The yellow and black laser beams traverse generally in a second scan direction 126, which is generally opposite of the first scan direction 124 as is illustrated traversing across the page from the left to the right. These scan direction orientations correspond to the manner in which the corresponding laser beam impinges the rotating polygon mirror as illustrated in FIG. 3. Referring thereto, a rotating polygonal mirror 36 in the optical system 26 includes a plurality of facets 38 thereon, and is operatively configured to rotate at a fixed rotational velocity. The laser system 24 includes a first laser 40 and a second laser 42 that are positioned in proximity to one another. Each of the first and second lasers 40, 42 emits a corresponding laser beam 44, 46 so as to impinge upon the same one of the facets 38 of the polygonal mirror 36. The laser system 24 also includes a third laser 48 and a fourth laser 50 that are positioned in proximity to one another and in spaced relation to the first and second lasers 40, 42. Each of the third and fourth lasers 48, 50 emits a corresponding laser beam 52, 54 so as to impinge upon the same one of the facets 38 of the polygonal mirror 36, which is different from the facet 38 impinged by the first and second beams 44, 46. As the polygonal mirror 36 rotates, the angle of each laser beam 44, 46, 52, 54 with respect to a particular facet 38 impinged thereby changes causing each laser beam 44, 46, 52, 54 to sweep in a corresponding scan plane in the direction of rotation of the polygonal mirror 36. Accordingly, it can be observed that the first and second laser beams 44, 46 will sweep in a scan direction that is generally opposite of the scan direction of the third and fourth beams 52, 54. Due to the unavoidable imprecision in the shape and mounting of the polygonal mirror 36 and optical system 26 with respect to each laser beam 44, 46, 52, 54, process direction errors including bow and skew are introduced into the image output. Referring back to FIG. 2, a plurality of test points, e.g., fifteen test points, labeled P0-P14 as shown, are detected and recorded at various locations across each scan plane 108, 110, 112, 114. The laser beam position measurements 30 stored on the memory device 28 in the printhead 14 correspond to measurements taken at these test points P0-P14 for each scan plane 108, 110, 112, 114. The number of test points and the interval(s) upon which the test points are taken can vary. For example, the number of measurements corresponding to each test point may be dependent upon the available system resources (e.g., the amount of memory allocated to store the test point data on the memory device 28 of the printhead 14 may be limited), or a desired level of precision for which the process direction position errors of written Pels are to be characterized. For purposes of clarity, the remainder of the discussion herein will be directed primarily towards a discussion of the black scan plane 114. However, the discussion applies equally as well to the cyan, magenta and yellow scan planes 108, 110, 112 with notable differences identified. The laser beam corresponding to the bitmap pixel data for the black image plane traverses in the second scan direction 126 across the page from the left to the right as illustrated. For convenience, the fifteen test points are correspondingly labeled, with test point P0 being the leftmost test point and P14 being the rightmost test point. The test points P0-P 14 represent measurements recorded of the actual laser beam position as the laser swept across the scan plane 114. It should be noted that the algorithms and systems according to the current embodiment of the present invention do not physically alter the scan path of each laser beam. Rather, by characterizing the process direction position errors of a laser beam, corresponding image data can be electronically warped or distorted in a manner such that during printing, the inherent process direction position errors of the laser “un-warp” the electronically warped image data such that corresponding Pels are printed with little or no process direction position errors, i.e., each written line of Pels is substantially straight and transverse to the process direction 104. The measurements for the test point P0 are expressed as Cartesian X, Y coordinates, where X0 represents the distance that test point P0 lies from the black beam position origin 122 in the scan direction 126 and Y0 represents the distance that test point P0 lies from the black beam position origin 122 in the process direction 104. Any suitable unit of measure, e.g., microns, millimeters, etc. may be used to record the measurement. The scan direction (X-axis) measurements for the remainder of the test points P1-P14, are taken relative to the preceding test point. For example, the measurement recorded for test point P1 in the scan direction 126 is distance in the scan direction 126 that test point P1 lies from test point P0, etc. This approach allows the size of each measurement to be kept relatively small, and reduces the amount of space necessary to store the measurements in a memory device. Alternatively, each test points P1-P14 may be expressed relative to the black beam position origin 122. The beam position measurements for each of the scan planes 108, 110, 112, 114 may be taken at some time during manufacturing of the apparatus and are stored in the memory device 28 or some other memory device accessible to the controller 12. An exemplary approach to measuring points along a laser beam scan path is set out in U.S. patent application Ser. No.______, Attorney Docket 2002-0711, entitled “Memory Device On Optical Scanner And Apparatus And Method For Storing Characterizing Information On The Memory Device” to the same assignee, the contents of which are already incorporated by reference herein. It may be desirable to describe the location of each of the beam position origins with respect to an arbitrary image system origin 128. As shown, an image system plane 130 (illustrated by the dashed box) encompasses each of the cyan, magenta, yellow and black scan planes 108, 110, 112, 114. The image system plane 130 thus defines a global coordinate system relative to each of the local coordinate systems for each corresponding scan plane 108, 110, 112, 114. The image system origin 128 thus allows each test point P0-P14 of each scan plane 108, 110, 112, 114 to be described in a global coordinate system. Again, the location of the image system origin 128 can be completely arbitrary. However, it may be convenient to select the location of the image system origin 128 to eliminate the need to process negative numbers. As shown, for convenience the image system origin 128 is located in the lower left hand corner, and is designated with a global address of (0,0). Relative to the image system origin 128, the scan direction is designated along the X-axis (across the page), with positive values to the right thereof. The process direction is designated along the Y-axis, with positive values above the image system origin 128. The coordinates of the cyan beam position origin 116 with respect to the image system origin 128 is Xc, Yc. The coordinates of the magenta beam position origin 118 with respect to the image system origin 128 is Xm, Ym. Similarly, the coordinates of the yellow beam position origin 120 with respect to the image system origin 128 is Xy, Yy, and the coordinates of the black beam position origin 122 with respect to the image system origin 128 is Xb, Yb. A correlation is also established between the printhead 14 and each of the scan planes 108, 110, 112, 114 by defining a printhead origin, i.e., a known, fixed point arbitrarily selected in the printhead. For convenience, the printhead datum is selected, however, any other position may alternatively be used. As shown, the printhead datum is projected down onto the page to define a printhead origin 132, which is located at coordinates Xs, Ys with respect to the image system origin 128. Based upon the above, it can be seen that the beam position measurements (test points P0-P14) from each of the scan planes 116, 118, 120, 122 can now be freely mapped between their respective local coordinate systems, to a system based relative to the printhead. Characterizing a Laser Beam The Laser Beam Scan Path Model Based upon the process and scan direction beam position measurements (X, Y) of the test points P0-P14 for a given scan plane 108, 110, 112, 114, it is possible to construct a corresponding laser beam scan path model 32 that characterizes the scan path of the corresponding laser beam. Essentially, the number of test points taken should be sufficient to allow each laser beam scan path to be approximated to a desired level of precision. However, knowledge of the laser beam scan path alone is not always sufficient to be able to correspond a particular Pel in a bitmap image to be printed, to a position along the scan path. This is because the location of a written Pel along a scan path will be affected by a number of factors including printer registration data and laser beam scanning velocity (which may change as the laser beam sweeps across its scan plane). Accordingly, information in addition to the X, Y coordinates may be necessary to properly characterize the process direction position errors of written Pels. The Pel Model and the Pel Profile In order to correspond the location of written Pels to particular positions along the scan path of a given laser beam, the laser beam scan path model 32 is converted into a Pel model 33 and corresponding Pel profile 34. The Pel model 33 maps the location of each test point P0-P14 to a Pel location and process direction offset. Correspondingly, the Pel profile 34 is essentially the Pel model 33 expanded out to include a mapping for each Pel location across a printed page. An exemplary approach to correspond a test point location P0-P14 to a particular written Pel location is to measure the position of each of the above described test points P0-P14 as a function of the angular position of the rotating polygonal mirror. A single start-of-scan signal 134 is provided for the laser beams corresponding to the cyan and magenta scan planes 108, 110, which is designated herein as CM SOS. Correspondingly, a single start-of-scan signal 136 is provided for the laser beams corresponding to the yellow and black scan planes 112, 114, which is designated herein as KY SOS. The start-of-scan is indicated schematically as the negative going edge of the corresponding signal. Again, with reference to the black scan plane 114, a predetermined amount of time after detecting the start of scan signal 136, a nominal detect to print signal (which is optionally modified by registration calibration data) indicates that the laser corresponding to the black scan plane 114 has reached the location where it can write the first Pel, designated Pel 0 (not shown in FIG. 2). It should be noted that the location of Pel 0 is a function of the time since detecting the start of scan signal 136 (DetTo Print(time)), and the angular velocity of the rotating polygonal mirror (ωpolygonalmirror). Accordingly, it may be convenient to store the nominal detect to print value as an angle measurement with respect to a known, fixed point, e.g., a start of scan sensor: A ndp ( degrees ) = ω polygonalmirror ( rev ) min × DetToPrint ( time ) ( sec ) × 360 ( degrees ) ( rev ) × 1 ( min ) 60 ( sec ) Such an approach normalizes the measurement and eliminates its dependency upon a potentially varying rotational velocity of the rotating polygonal mirror. In a similar fashion, an angle A0 is measured, which corresponds to an angular change of the rotating polygonal mirror with respect to the start-of-scan signal 136 as the laser beam corresponding to the black scan plane 114 crosses the first test point P0. The angles A1-A14 are similarly measured, but are recorded relative to the preceding measurement as delta mirror angles to reduce storage requirements. That is, A1 is the change in the angle of the rotating polygonal mirror since A0, etc. The angles discussed herein may be measured as is set out in U.S. patent application Ser. No.______, Attorney Docket 2002-071, entitled “Memory Device On Optical Scanner And Apparatus And Method For Storing Characterizing Information On The Memory Device” to the same assignee, the contents of which are already incorporated by reference herein. It should be noted that the first beam position measurement, e.g., test point P0, does not necessarily correspond to the Pel 0 location, i.e., the location where the first Pel that fits onto a physical page. Similarly, the last beam position measurement, e.g., test point P14, does not necessarily need to correspond to the last Pel that can be written to a particular print medium, i.e., the last Pel that can be written to a physical page along a scan line. Rather, the beam position measurements 30 (such as the test points P0-P14 for each scan plane 108, 110, 112, 114) can be taken anywhere along the laser beam scan path and should be selected so as to characterize the scan path for each scan plane to the desired level of precision required for a particular application. For example, it may be desirable to intentionally locate select ones of the beam position measurements outside the boundaries of the typical expected printed page. Beam Position Measurement Data Some of the data used to compute a bow profile 35 for each laser beam scan path is recorded in one or more tables in the memory device 28 on the printhead 14. Table 1, below, is merely illustrative of the manner in which those beam position measurements 30 may be stored. As can be seen in the table below, each color image plane 108, 110, 112, 114 includes entries that identify the coordinates of the corresponding local beam position origin 116, 118, 120, 122 relative to the image system origin 128 and corresponding beam position measurements (X, Y and A for each corresponding test point P0-P14). The scan direction (X-axis) measurements for each of the test points P0-P14 for each color scan plane 108, 110, 112, 114 are encoded into two byte values, and the fifteen corresponding X-axis values for each scan plane 108, 110, 112, 114 are concatenated into a single, 30 byte vector. The encoding for the scan direction (X-axis) measurements is applied likewise to the process direction (Y-axis) measurements and the Angle measurements. The table also stores the rotating polygonal mirror angular position Andp corresponding to the nominal detect to print signal for each scan plane, the printhead origin coordinates as an offset from the image system origin 128, and the time period between the start of scan (CM SOS and KY SOS) and end of scan (EOS) signals. TABLE 1 Printhead Memory Allocation Table Name Units Size Description Xc microns 4 X Offset from image system origin to cyan coordinate system Yc microns 4 Y Offset from image system origin to cyan coordinate system Cyan X Vector microns 30 Delta X vector for cyan with respect to (wrt) cyan beam position origin. Cyan Y Vector microns 30 Y vector for cyan wrt cyan beam position origin. Cyan A Vector Δ degrees 30 Delta angle vector for cyan wrt to SOS. Cyan Nominal DetPrt Δ degrees 2 Nominal DetPrt wrt to SOS in degrees* 8192 Xm microns 4 X Offset from image system origin to magenta coordinate system Ym microns 4 Y Offset from image system origin to magenta coordinate system Magenta X Vector microns 30 Delta X vector for magenta wrt magenta beam position origin Magenta Y Vector microns 30 Y vector for magenta wrt magenta beam position origin. Magenta A Vector Δ degrees 30 Delta angle vector for magenta wrt to SOS. Magenta Nominal Δ degrees 2 Nominal DetPrt wrt to SOS in degrees* DetPrt 8192 Xy microns 4 X Offset from image system origin to yellow coordinate system Yy microns 4 Y Offset from image system origin to yellow coordinate system Yellow X Vector microns 30 Delta X vector for yellow wrt yellow beam position origin. Yellow Y Vector microns 30 Y vector for yellow wrt yellow beam position origin. Yellow A Vector Δ degrees 30 Delta angle vector for yellow wrt to SOS. Yellow Nominal DetPrt Δ degrees 2 Nominal DetPrt wrt to SOS in degrees* 8192 Xb microns 4 X Offset from image system origin to black coordinate system Yb microns 4 from image system origin to black coordinate system Black X Vector microns 30 Delta X vector for black wrt black beam position origin Black Y Vector microns 30 Y vector for black wrt black beam position origin. Black A Vector Δ degrees 30 Delta angle vector for black wrt to SOS. Black Nominal DetPrt Δ degrees 2 Nominal DetPrt wrt to SOS in degrees*8192 Xs uM 2 Printhead origin offset from Image System origin Ys uM 2 Printhead origin offset from Image System origin CM SOS to EOS ns 4 Cyan/Magenta SOS to EOS KY SOS to EOS ns 4 Black/Yellow SOS to EOS Building the Profiles in Memory Referring to FIG. 4, a flow chart illustrates a method 200 for constructing a bow profile from laser beam position measurements. The method may be implemented for example, by software instructions executed on the microprocessor 18 in the controller 12 and may be repeated for each color scan plane 108, 110, 112, 114. Initially and in the illustrated embodiment, the corresponding beam position measurements are read from the printhead memory device 28 at 202. A corresponding laser beam scan path model 32 is constructed from the laser beam position measurements 30 at 204. At this stage, each laser beam scan path model 32 may comprise a set of X-Y coordinates for a plurality of test points with respect to the printhead origin 132 (e.g., the printhead datum) and corresponding angle measurements that define the rotating polygonal mirror angle for each of the test points. Next, the laser beam scan path model 32 is rotated at 206, and optionally, manipulated, e.g., magnified, scaled and/or skew adjusted, based on the registration or calibration inputs at 208. The rotated and manipulated laser beam scan path model 32 is then converted into a Pel model 33 at 210. The Pel model 33 is converted into a Pel profile 34 at 212. The Pel profile 34 is then converted into a bow profile 35 at 214. The rotation, manipulation and conversion of the model are explained in greater detail below. Creating a Laser Beam Scan Path Model Referring to FIG. 5, a flowchart illustrates a more detailed method 300 for computing a bow profile 35. The following procedure is repeated by the software instructions executed on the microprocessor 18 for each of the four sets of laser beam position measurements stored in the memory device 28, and may be executed prior to performing a printing operation, during printhead installation, during printer startup or reset, or when necessary, e.g., due to a change in certain operational parameters such as an adjustment to the print output resolution or the adjustment of registration data. The necessary variables are initialized at 302. For example, the laser beam position measurements 30 are retrieved from the memory device 28 by the microprocessor 18 and are stored as arrays in an appropriate memory location within the printer. Assume that there are n measured beam positions, which may be in a format as set out in Table 1, e.g., fifteen measurements for each scan plane where each beam position is characterized by X, Y coordinates and a corresponding polygon mirror angle A. Three arrays are dimensioned in appropriate memory locations within the printer for each laser beam. For clarity herein, the three arrays for each beam are designated Angle[ ], X_vector_wrt_printhead[ ], and Y_vector_wrt_printhead[ ], all of size n. The angle array Angle[ ] is populated with the angle measurements A for a given scan plane. The first angle value A0 is read out from the memory device 28 at 304. Depending upon how the angle measurement was recorded, it may be necessary to scale the angle read from the memory device. For example, a scanner angle may be measured to within several decimal places of accuracy. In order to avoid storing angles with their fractions, a scaling may optionally be provided to the measurement before being stored in memory. That is, each measured angle may be multiplied by an integer that is at least as large in magnitude as the number of decimals of precision of the angle measurement being scaled to convert that angle to an integer. For example, a hypothetical angle measurement of 5.612 degrees can be scaled by an integer greater than, or equal to 1000 (corresponding to three decimal places of precision). In one exemplary application, each angle measurement is scaled (multiplied) by 8192. As such, when reading the angle measurements out from the memory device 28, the first angle value A0 is adjusted to remove the scaling factor by dividing the value A0 by 8192 (or what ever value was used to scale the angle measurements), and the results of the computation are stored in the Angle array. That is, Angle[0]=A0/8192. The remaining fourteen angles A1-A14, stored in the memory device 28 are treated as offsets from the first angle Angle[0] and are derived by reading out an angle values, converting the angle, e.g., dividing the corresponding value by the scaling factor, e.g., 8192, and adding it to the previous angle at 310. For example, Angle[1]=A1/8192+A[0]; Angle[2]=A2/8192+A[1] etc. This generalizes to: Angle[k]=Ak/8192+Angle[k−1] where 1<=k<=n−1 and n=total number of entries in the array. As noted above, the scan direction and process direction beam position measurements (X, Y) for each of the sets of test points P0-P14 are stored in the memory device 28 relative to their local scan plane origin 116, 118, 120, 122. However, to construct a corresponding laser beam scan path model 32, the X and Y values must be expressed with respect to the printhead origin 132. For each scan plane, the first X measurement (X0) is read at 312, and is converted to a measurement relative to the printhead origin at 314. The above calculation is as follows for a beam position measurement corresponding to the black scan plane 114: x—vector—wrt—printhead[0]=X0+Xb−Xs; Because the remainder of the X measurements for the black scan plane 114 are offsets relative to the previous measurement, subsequent X measurements are read at 316 and are converted to an offset measurement relative to the printhead origin 132 at 318. The subsequent X measurements are calculated by adding the next offset to the previously computed value. x—vector—wrt—printhead [k]=x—vector—wrt—printhead[k−1]+Xk; where 1<=k<=n−1. Notably, because the remainder of the test points X1-X14 are offsets, only the first test point X0 needs to be mapped to the printhead origin. Similarly, for the yellow scan plane 112: x—vector—wrt—printhead[0]=X0+Xy−Xs; x—vector—wrt—printhead [k]=x—vector—wrt—printhead[k−1]+Xk; where 1<=k<=n−1. However, for the cyan and magenta beams, the computations must be inverted because the laser scan direction is opposite that of the yellow and black laser beams as noted above. That is, for the cyan scan plane 108: x—vector—wrt—printhead[0]=−1*X0+Xc−Xs; Subsequent X components of the vector are derived by subtracting the current X measurement from the previous offset. x—vector—wrt—printhead [k]=x—vector—wrt—printhead[k−1]−Xk; And for the magenta scan plane 110: x—vector—wrt—printhead[0]=−1*X0+Xm−Xs; x—vector—wrt—printhead [k]=x—vector—wrt—printhead[k−1]−Xk; where 1<=k<=n−1. The Y measurements for each scan plane are read from the memory device 28 at 310 and are converted to measurements relative to the printhead origin at 322. Notably, the Y direction is oriented consistently for each color scan plane. Moreover, each Y measurement is recorded as an absolute value with respect to the corresponding local scan plane origin. Accordingly, the Y measurements are calculated as follows for all four beams: y—vector—wrt—printhead[k]=Yk+Yc−Ys; y—vector—wrt—printhead[k]=Yk+Ym−Ys; y—vector—wrt—printhead[k]=Yk+Yy−Ys; y—vector—wrt—printhead[k]=Yk+Yb−Ys where 0<=k<=n−1. Upon completing the above calculations, the data points for each color plane define a laser beam scan path model 32 that describes the corresponding laser beam scan path. Each model is rotated at 324, optionally adjusted, such as for skew at 326, and the bow profile is created at 328. These processes are set out below. Rotation of the Laser Beam Model An exemplary laser beam scan path model 32 is schematically represented in FIG. 6 as it appears on the corresponding PC drum. In practice, the photoconductive drum surface transfers a developed image, i.e., a toner image, onto a printed page as a mirror image of that on the photoconductive drum. Therefore, each laser beam scan path model 32 must be rotated about a corresponding PC drum axis 140 so that the laser beam scan path model 32 represents what would appear on a printed substrate or page. That is, the data points of each laser beam scan path model 32 must be repositioned in the process direction so as to define a mirror image of the scan path of the corresponding laser beam. For example, as shown, the test point measurements that comprise the corresponding laser beam scan path model 32 have been smoothly connected to represent a laser beam scan path profile 142 as the corresponding laser beam traverses across its scan path. Notably, the data points that comprise the laser beam scan path model 32 are schematically illustrated as a curve 142 for illustrative purposes. As shown, the curve 142 has a Y offset 143 from the printhead origin 132 to the curve 142. The PC drum has a Drum offset 144 from the printhead origin 132. In order to translate the laser beam scan path model 32 to the substrate, the model must be rotated about the PC drum axis 140 according to the following formula: y—vector—wrt—printhead[k](rotated)=2*Drum offset−Y offset for k=0 to n−1. After rotation, the laser beam scan path model 32 should be rotated about the PC drum axis 140 as shown in FIG. 7. Laser Beam Model Adjustments Referring back to FIG. 5, the laser beam scan path models may optionally be adjusted at 326. Such adjustments can be used to compensate for characteristics such as additional laser beam bow and/or skew. Before performing such adjustments, a few necessary parameters are examined. Locating the First Writable Pel For each Pel profile 33, Pel 0 begins at the position where a corresponding detect-to-print control signal expires. The detect to print control signal is actually a combination of a nominally stored value and an offset that is stored as part of the machine registration data. The nominal detect to print component is schematically illustrated in FIG. 2 by the angle Andp (the angle of the rotating polygon mirror at the nominal detect-to-print signal expiration) as noted above. Accordingly, to determine the location of Pel 0, the detect to print control signal must be converted to a beam angle. However, the offset from the stored registration data may be stored in other formats. As such, it may be convenient to convert the nominal detect to print angle Andp to a time DetTo Print(time), convert the offset to a time, add the DetTo Print(time) to the offset time, then convert the results back to an angle. To convert Andp to a time: DetToPrint ( time ) = A ndp ( degrees ) * ( rev ) 360 ( degrees ) * 1 ( min ) ω polygonalmirror ( rev ) * 60 ( sec ) 1 ( min ) where ωpolygonalmirror is the angular velocity of the rotating polygonal mirror. The approach used to convert the offset will depend upon how the offset is stored. For example, an offset may be represented by a signed integer (so that the location of Pel 0 can be adjusted to the left or right) where each increment (+ or −) corresponds to a given number of Pel locations per value at a specified resolution. For example, one increment of offset may be defined as four Pel locations at 600 dpi. This example is converted to time by the following formula: Offset ( time ) = OffsetValue * PelsPerValue * CurrentResolution OffsetResolution * SubClocksPerPel * TimePerClock So, assume that the system is working at a 1200 dpi resolution, the stored Offset is +1, each offset represents 4 Pels at 600 dpi and there are six slice clocks or sub clocks per Pel. This corresponds to 1*4*1200/600*6*τ or an offset in of 48τ where τ is the period of a clock cycle. The angle for Pel 0 is thus: Angle ( Pel0 ) = ( DetToPrint ( time ) + Offset ( time ) ) ( sec ) * 360 ( degrees ) ( rev ) * ω polygonalmirror ( rev ) ) ( min ) * ( min ) 60 ( sec ) Linear Interpolation With the beam angle of Pel 0 computed for a given scan plane 108, 110, 112, 114, a search is conducted of the corresponding beam position angle measurements Angle[k] (0≦k≦n−1) for that scan plane to find the two beam measurements that the angle falls between. Essentially, the search identifies the upper bound and the lower bound of Pel 0. An assumption is then made that the X position of the beam is linear with respect to beam angle between the upper and lower bounds. The X position of Pel 0 is then found using linear interpolation by the following formula: Pel 0 X position=(Pel 0 beam angle−lower bound beam angle)/(upper bound beam angle−lower bound beam angle)*(upper bound X position−lower bound X position)+lower bound X position The Y position maybe found with the following formula: Pel 0 Y position=(Pel 0 beam angle−lower bound beam angle)/(upper bound beam angle−lower bound beam angle)*(upper bound Y position−lower bound Y position)+lower bound Y position It is possible depending upon the value of the skew correction offset and the selection of the location for the test points that the location of Pel 0 does not fall between any two test points. That is, the first test point P0 may be past the location of Pel 0 in the scan direction. Under these circumstances, the X position of Pel 0 can be extrapolated from the slope of a line achieved by connecting P0 to P1. Locating the Last Writable Pel Position The scan direction location of Pelm is determined based upon the intended output size of the printed media. For example, for standard letter sized output, the scan direction measurement of Pelm relative to Pel 0 is 8.5 inches (21.6 cm, 215,900 microns). The Y-offset of Pelm is determined using linear interpolation (if Pelm is bounded by test points) or extrapolation otherwise. For example, assume that test point P13 is a lower bound and that P14 is an upper bound on Pelm. Also, assume that ΔX_Pelm is the scan direction distance between Pelm and P13. PelmYoffset=ΔX—Pelm*(y—vector—wrt—printhead[14]−y—vector—wrt—printhead[13])/(x—vector—wrt—printhead(rotated)[14]−x—vector—wrt—printhead(rotated)[13])+y—vector—wrt—printhead(rotated)[13] Likewise, the last beam position measurement may be located at a Pel location less than Pelm. If this occurs, the process direction offset of Pelm may be extrapolated from the last two test points. For example, using a linear extrapolation, the slope of the interval between the last two measurements is taken. For example, using the above fifteen test points: slope = y_vector _wrt _printhead ( rotated ) [ 14 ] - y_vector _wrt _printhead ( rotated ) [ 13 ] x_vector _wrt _printhead [ 14 ] - x_vector _wrt _printhead [ 13 ] The X-axis (scan line) position of Pelm(which results in an X-location beyond the last X sample location) is known as noted above. The determined slope is multiplied by the difference between the Pelm X position and the last sample, X position. The above result is then added to the Y-axis measurement of the last test point, and the last sample location is converted to be Pelm with the proper Y offset in Pels. Assume that ΔX_Pelm is the scan direction distance between Pelm and P14. PelmYoffset=slope*ΔX—Pelm+y—vector—wrt—printhead[14] Bowing and Skewing the Laser Beam Scan Path Model in Memory The laser beam position measurements 30, noted above, are taken prior to installing the printhead 14 in a corresponding printer, and will indicate if one or more laser beams are creating bowed and/or skewed scan lines. However, additional bowing and/or skewing of one or more laser beams may result after installation of the printhead 14 in the printer. So as to detect any additional bowing and/or skewing of a scan line written by any of the laser beams, a user or technician can perform registration diagnostics and provide correction adjustments to the printer, to compensate for bow and/or skew of one or more laser beams. For example, a test page may be printed and analyzed. An operator can then provide adjustments, such as by entering correction values into an operator panel on the device. The correction values may be stored in a memory location accessible by the controller 12 including being stored in the memory device 28 on the printhead 14. Skew Compensation As an example, a skew correction offset may be used to indicate the process direction amount of skew detected on the test page as measured from a point near the leftmost edge of the test page relative to a point near the rightmost edge of the test page. A positive offset correction value may indicate that the process direction amount of skew is towards the top of the page. Correspondingly, a negative offset correction value may indicate the process direction amount of skew towards the bottom of the page. The skew measured from the test page above, is an offset of a fixed point located near the rightmost edge of the printed test sheet (this corresponds to location Pelm discussed above) relative to a fixed point near the leftmost edge of the printed test sheet (which corresponds to location Pel 0 discussed above). Let the skew measured from the test page be designated as Δym. Because the skew is a rotation of the laser beam scan path about Pel 0, a new Δy will have to be calculated for each test point in the laser beam scan path model 32. Thus it can be seen that skew correction can be accomplished by the below formula. y—vector—wrt—printhead[k](rotated and skew corrected)=y—vector—wrt—printhead[k](rotated)+Δyk for 0<=k<=14 (for all test points) Any skew present in a given laser beam when the corresponding beam position measurements P0-P14 were taken prior to assembly of the printhead into the printer is taken into account by y_vector_wrt_printhead[k](rotated). Any additional skew amount resulting after installation of the printhead in the printer is taken into account by Δyk. Finding the Process Direction Offset Due To Skew Correction Referring to FIG. 8A, points Pel 0 and Pelm are plotted on a graph where the process direction values are plotted on the Y-axis and the corresponding angle measurements are plotted on the X-axis. The test points therebetween have been removed for clarity. In general terms, the Pel 0 coordinates are designated as α0, y0 where α is the rotating polygonal mirror angular measurement at the location of Pel 0, and y0 is the corresponding process direction offset. Correspondingly, the Pelm coordinates are designated as αm, ym . Alternatively, the coordinates for the last test point P14 may be substituted therefore. For conceptual purposes, an imaginary first straight line 150 is drawn connecting α0, y0 to αm, ym. Based upon the first straight line 150, a theoretical right triangle 152 may be defined, and an angle θm can be computed as follows: tan θ m = ( y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) θ m = tan - 1 [ ( y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) ] It should be noted that the bow and skew inherent in the laser beam at the time that the corresponding beam position measurements 30 were taken, are incorporated into the process direction offsets (y0) for Pel 0 and (ym) for Pelm. Assume that additional skew correction is provided as an operator entered, skew correction offset as noted above corresponding to additional skewing occurring after the installation of the printhead 14 in the printer. For illustrative purposes, assume that the additional skew causes a corresponding scan line to be rotated upwards so as to move the endpoint ym up by an additional Δym Pels. The value Δym thus corresponds to the skew correction offset entered by the operator in the operator panel. A second imaginary line 154 is drawn connecting α0, y0 to αm, (ym+Δym). The second imaginary line 154 is provided for contextual purposes to help envision the skew correction method set out herein. As can be seen, the second imaginary line 154 is merely the first imaginary line 150 rotated about Pel 0 by the angle β. As such the corresponding new angle for the new right triangle 156 is (θm+β), which can also be expressed by: tan ( θ m + β ) = ( Δ y m + y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) ( θ m + β ) = tan - 1 [ ( Δ y m + y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) ] It can be observed that the angle β will be constant for each laser beam measurement in the corresponding laser beam scan path model 32 because, as noted above, it was presumed that the additional skewing resulting from the entire scan line being pivoted or rotated about a fixed point, e.g., Pel 0. However, the angle θ may vary for each test point in the laser beam scan path model 32 because the process direction value (y_vector_wrt_printhead[k](rotated)) corresponding to each test point will likely not fall on the first imaginary line 150. An example of this is illustrated in FIG. 8B, which shows a few exemplary data points plotted to illustrate that the angle θ for each data point P relative to Pel 0 may vary. Therefore, it may be convenient to solve for β as follows: β=(θm+β)−θm β = tan - 1 [ ( Δ y m + y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) ] - tan - 1 [ ( y m - y 0 ) ( x ( α m ) - x ( α 0 ) ) ] An angle θk with respect to Pel 0 can be computed for each corresponding angle measurement αk i.e., each angle laser beam position measurement as follows: θ k = tan - 1 [ ( y k - y 0 ) ( x ( α k ) - x ( α 0 ) ) ] for k<=0<=n−1. With β known and θk determinable, the process direction change Δyk due to the skew rotation can be computed for each test point. tan ( θ k + β ) = ( y k + Δ y k - y 0 ) ( x ( α k ) - x ( α 0 ) ) Accordingly, the corresponding y offset Δyk can be computed. Δyk=(x(αk)−x(α0))*tan(θk+β)−yk+y0 Each computed offset Δyk for each test point is added to its process direction offset (y-value) to achieve the skew corrected value. That is, y—vector—wrt—printhead[k](rotated and skew corrected)=y—vector—wrt—printhead[k](rotated)+Δyk for 0<=k<=14 (for all test points) Bow Compensation A bow correction offset may be used to indicate the process direction amount of bow detected on a printed test page. For example, to determine an amount of bow, three targets may be printed on the test page along a common line, including a first target printed near the leftmost edge of the test page, a second target printed near the rightmost edge of the test page, and a third target printed generally at the midpoint between the first and second targets. The amount of bow may be determined by analyzing the first, second and third targets, and computing the offset of the third (midpoint) target relative to the first and second (endpoint) targets. For example, the position of the third target in the process direction (up the page) may be compared to the average of the first and second targets in the process direction, and a correction may be entered into the printer. The position of the first and second targets may be averaged to factor out the effects of any skew present in the printing of the test page. The correction offset corresponding to the amount of detected bow may be either positive, indicating a bow correction is required in a first direction, or negative, indicating a bow correction is required in a second direction. Because bow can be generally characterized as a parabola that affects the laser beam scan path, a Δybowcorrection may be calculated and used to modify the process direction position value for each test point in the corresponding laser beam scan path model 32. Any bow present in a given laser beam when the corresponding beam position measurements P0-P14 were taken prior to assembly of the printhead into the printer is taken into account by y_vector_wrt_printhead[k](rotated and skew corrected). Any additional bow amount resulting after installation of the printhead in the printer is thus taken into account by Δyk—bowcorrection. Characterizing the Bow Offset Correction Value The manner in which bow compensation is performed will depend upon the manner in which bow information is extracted from the test sheets. However, as an example, it may be assumed that a bow offset entered into the operator panel represents an offset adjustment that would be required to straighten out the bowed line. To simplify the computations necessary to map the offset derived from the test sheet to each test point in the corresponding laser beam scan path model 32, it may be assumed that the additional bow is represented by a vertical parabola having X-axis intercepts defined by the first and last test points, e.g., P0 and P14, and a vertex defined by coordinates at the midpoint between P0 and P14 with a Y-axis offset defined by the operator entered bow offset. That is, it may be assumed that a vertical parabola is constructed in an imaginary plane having its origin at the coordinates corresponding to test point P0. As such, the parabola passes through test point P0 at location (0,0) and passes through test point P14 at location ((x_vector_wrt_printhead[14]−x_vector_wrt_printhead[0]), 0). In the above example, a positive bow offset correction value indicates that the third (midpoint) target is above the first and second (endpoint) targets, i.e., the vertical parabola opens downward. Correspondingly, a negative bow offset correction value indicates that the third (midpoint) target is lower than the first and second (endpoint) targets, i.e., the vertical parabola opens upward. To compute the coordinates for the vertex of the parabola, some data conversion may be required. For example, the bow offset correction may be entered as a signed integer corresponding to a predetermined increment of bow offset, e.g., each increment may correspond to 1/1200th of an inch of correction. However, the coordinates corresponding to the associated test points P0-P14 may be stored in a different unit of measure, e.g., microns. Given the above exemplary units of measure, the Y coordinate of the vertex of the parabola is computed in microns as follows. Y(max parabola height)=(bow offset)*1/1,200 in*25.4 mm/in*1000 microns/mm The max parabola height is assumed to occur at the midpoint between the first and last test points, e.g., P0 and P14, thus: X(max parabola height)=1/2*(x—vector—wrt—printhead[14]−x—vector—wrt—printhead[0]) A first basic equation for a parabola may be expressed as: y=ax2+bx+c Based upon the above assumptions, three data points that lie along the path of the imaginary vertical parabola are known thus each of the coefficients a, b and c may be computed. Notably, the assumption that test point P0 lies at location (0,0) simplifies the solution for the coefficients because c is trivially zero. Given that c=0, the coordinates corresponding to test point P14 may be inserted into the first basic equation of a parabola and the coefficient b may be solved for in terms of the coefficient a. That is: b=−a*(x—vector—wrt—printhead[14]−x—vector—wrt—printhead[0]) Thus it can be seen that: a = Y ( max parabola height ) X ( max parabola height ) 2 - [ X ( max parabola height ) * ( x_vector _wrt _printhead [ 14 ] - x_vector _wrt _printhead [ 0 ] ) ] As another simplifying step, the basic equation for the parabola may be represented by the equation: y=a(x−h)2+k where h is the X-axis coordinate of the vertex (X(max parabola height)) and k is the Y-axis coordinate of the vertex (Y(max parabola height)). Accordingly, the general equation for the parabola can be rewritten as follows: Δyk—bowcorrection=α((x—vector—wrt—printhead[j]−x—vector—wrt—printhead[0])−h)2+k for 0<=j<=14 (for all test points) Accordingly, bow correction based upon the corresponding bow offset derived from the registration diagnostics can be accomplished by the below formula. y—vector—wrt—printhead[k](rotated, skew and bow corrected)=y—vector—wrt—printhead[k](rotated and skew corrected)+Δyk—bowcorrection for 0<=k<=14 (for all test points) Of course, each color image plane may have a unique bow offset, so the above corrections may be independently computed for the test points for each color image plane. Other Miscellaneous Corrections Also, once the laser beam scan path model 32 is properly constructed, it is possible to perform any sort of scaling thereof. For example, margin adjustments, the lengthening or shortening of a line can be implemented by scaling the corresponding computed laser beam scan path model 32. It should also be noted that the velocity of the laser beam changes as it is swept in a scan direction. As such, some linearity correction may be required. Linearity correction and margin/line length corrections are set out in U.S. patent application Ser. No.______, Attorney Docket 2003-0848, entitled “Systems For Performing Laser Beam Linearity Correction And Algorithms And Methods For Generating Linearity Correction Tables From Data Stored In An Optical Scanner”, which is already incorporated by reference herein. Converting the Laser Beam Scan Path Model to a Pel Model It is often easier to work in Pels compared to other distance based position measurements, e.g., microns, millimeters, etc., when converting a given laser beam scan path model 32 to a corresponding Bow profile 35. Referring back to FIG. 5, the rotated and skew adjusted laser beam scan path models 32 are converted into corresponding Pel models 33 at 328. A Pel model 33 is essentially a laser beam scan path model 32 where scan direction measurements in the laser beam scan path model are converted to Pel locations, and rotated and skew corrected process direction measurements in the laser beam scan path model 32 are converted to Pel offsets. Notably, when creating the Pel model 33, the system may only be concerned with the Pel positions that can be written to a page. As such, the Pel model 33 may contain Pel locations and corresponding offsets falling within the range of Pel 0 to Pelm. The test points from the corresponding laser beam scan path model 32 between and including Pel 0 and Pm thus define the Pel model 33. For each Pel model 33, the Y offset in Pels are found by converting the scale of the corresponding process direction (rotated and skew corrected Y values) from the associated laser beam scan path model 32, e.g., microns, millimeters, etc., to Pels using an appropriate conversion taking resolution into account. For example, microns may be converted to Pels at 1200 dpi using the following equation: 1200 dpi Pel—y—vector—wrt—printhead[k](rotated, skew and bowcorrected)=y—vector—wrt—printhead[k](rotated, skew and bow corrected) in microns÷1000 microns/mm÷25.4 mm/inch*1200 dots/inch (the desired resolution) As noted above, with regards to the scan direction, i.e., the Pel locations, the first entry into the Pel model starts at Pel 0. An exemplary method for finding Pel 0 was set out above in the discussion of “Locating the First Writable Pel”, where Pel 0 was found through linear interpolation or extrapolation. The Pel location for each test point in an associated laser beam scan path model 32 is calculated by taking the difference in the scan direction (X positions) of two adjacent test points in the corresponding laser beam scan path model 32, and converting that distance into a distance in Pels at a given resolution. This can be accomplished for example, by applying an appropriate scaling, an example of which is shown above. That is, the distance measurement is converted to inches and is multiplied by the desired resolution in dots per inch. That result is added to the Pel location of the previous test point. For example, assuming a resolution of 1,200 dpi, to find the Pel location and offset corresponding to test point Pj, the following equation may be used. Of course, other resolutions may alternatively be used, and the equations should be modified accordingly. It should also be noted that if a computed Pel value is fractional, then the value may be rounded to the nearest Pel. X—test point(j)=(x—vector—wrt—printhead[j]−x—vector—wrt—printhead[/j−1]) in microns÷1000 microns/mm÷25.4 mm/inch*1200 dots/inch+X—test point(j−1) for j=1 to n−1. If it is necessary to compute the Pel location corresponding to test point P0, an equation such as the one below may be used. X—test point(0)=(x—vector—wrt—printhead[0] in microns÷1000 microns/mm÷25.4 mm/inch*1200 dots/inch Y offset test point(j)=y—vector—wrt—printhead[j]rotated, skew and bow corrected)in microns÷1000 microns/mm÷25.4 mm/inch*1200 dots/inch The last Pel location in each Pel model (Pelm) may be derived based upon the desired output and the print resolution of that output. For example, for standard letter size print media (8.5 inches or 21.6 centimeters) at 1,200 dpi resolution, the location of Pelm would be 10,200 (8.5×1,200). At 600 dpi and a standard letter sized print media, the location of Pelm would be 5,100 (8.5×600), etc. The y offset in Pels for location Pelm is: Y offset Pelm(in Pels)=y—offset Pelm(rotated, skew and bow corrected)in microns÷1000 microns/mm÷25.4 mm/inch*1200 dots/inch When analyzing the converted beam position measurements, a number of checks may be established. For example, it is possible for a beam measurement location to be positioned beyond a printed page. If such occurs, processing should stop traversing through the data points and move on to the next task. The Pel Profile The Pel models 33 are expanded into corresponding Pel profiles 34 at 330. For example, the microprocessor 18 may assign an offset for each Pel location between Pel0 and Pelm. This can be performed by curve fitting, linear approximation or any other desired line connecting algorithms. An example is discussed below. Data Structure for the Pel Profile The Pel profile 34 can be represented as a data structure having generally, three fields including a channel, a software offset and a bit profile. The channel defines which hardware channel is the current Pel profile 34 intended, i.e., which color image plane (cyan, magenta, yellow or black-CYMK) is the current Pel profile 34 associated with. The software offset defines the initial offset from “top” of profile at a given resolution (e.g., in 1200ths). The software offset is calculated by taking the Pel 0 y position and calculating how many Pels it is below the maximum Y offset of the Pel profile 34. A bit profile is used to actually encode the shape of the Pel profile 34. The bit profile assigns two bits per Pel location (two bits per Pel), encoded as follows: 00—no bow; 01—bow down the page by 1/1200th; 11—bow up the page by 1/1200th; and 10—invalid value. Of course, other assignments may alternatively be used. The above assumes a resolution of a 1,200th (1,200 dpi) in both the scan and process directions, which can also vary depending upon the specific application and scaling for other resolutions can easily be implemented in the alternative. Rules for Constraining the Pel Profiles In order to facilitate efficient processing of the Pel profile 34, it is convenient to establish some rules that limit the scope of processing thereon. For example, one rule may assert that all Pel profiles are provided in “Left to Right” format as seen on the front side of a simplex page. Another rule asserts that as the Pel profile is “walked” bit by bit, the minimum offset should be 0. This means that the Pel profile 34 will “reach into” or include the uncorrected line of bitmap image data at least once, i.e., at least one Pel will not be shifted from its original line location in the process direction compared to the original bitmap image. Another way to visualize this is that the “highest” point on the Pel profile 34 will have an offset of 0. Another convenient area to establish rules is to limit the “amplitude” of the Pel profile 34. As used herein, a vertical shift from one row of Pels to another is referred herein as a jump. Thus an exemplary rule may limit the magnitude of jumps for the entire Pel profile to 127 jumps or less. That is, the amplitude or maximum Y offset for any Pel between Pel 0 and Pelm, e.g., Pel 10,200 must be 127 or less. If the Pel profile 34 is to be used for bowing relatively low resolution print data, e.g., at 1200×1200 dpi or less print resolution, a rule may assert that it is invalid to have a jump on consecutive locations of the profile. Notably, a jump on consecutive Pels in the Pel profile 34 may be acceptable when printing a relatively high process direction, e.g., 2400×600, because the scan resolution doubles to 2400 compared to the 1,200 dpi case. The limitation of the amplitude of jumps to 127 (or any other arbitrary number) provides an overall check that limits the amount of electronic correction that can be used to compensate for laser process direction errors. However, it may further be helpful to establish rules that limit the total number of jumps within a smaller window. An exemplary rule in this regard may hold that it is not valid to have a bow magnitude of 8 or more jumps within a rolling 64-bit window in the Pel profile 34. Under such a rule, the maximum slope, i.e., amount of electronic correction to laser beam process direction position errors that can occur in any rolling 64-bit window is 7 jumps. An exemplary section of a Pel profile 34 is set out in Table 2 to illustrate the two bits per Pel instructions. TABLE 2 An Exemplary Section of a Pel Profile 1 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 1 0 1 As discussed more explicitly below, to transform a Pel model 33 having a limited number of measurements to a Pel profile 34 that encompasses Pel locations from Pel 0 to Pelm, the software executed by the microprocessor 18 defines a data structure that identifies the associated color image plane, a software offset, and a bit profile that represents the relative changes in process direction position of each Pel location along the associated scan path. In constructing each Pel profile 34, a few simplification processes can be implemented. For example, at 1,200 dpi printing, there are 10,200 Pels between Pel 0 and Pelm and two bits may be used to encode whether a relative process direction change occurs at each Pel location. As such, at least 20,400 bits are required in the bit profile to characterize the corresponding laser beam scan path. Accordingly, the Pel profile 34 is divided up into a plurality of arbitrarily sized words. For example, assume that each word comprises 32 bits and the resolution is 1200 dpi. Then 640 32-bit words are required to characterize the Pel profile 34. Reading from left to right then, Pel 0 is represented as bits 31-30 in the first word. Pel 1 is represented as bits 29-28 in the first word and so on. Pel 15 is represented as bits 1-0 in the first word etc. Referring to FIG. 9, a method 400 of constructing a Pel profile 34 for each color image plane can be implemented by initializing the channel to a value that defines its corresponding color image plane (CYMK). The value for the software offset is computed by reading the Y offset value corresponding to Pel 0 at 404. Each of the Y offset values in the associated Pel model 33 are then compared to determine a maximum Y offset of the model at 406. The software offset is then defined as the maximum Y offset minus the Y offset of Pel 0. The software offset thus essentially characterizes the number of rows of Pels that the Pel 0 process direction offset (Y-value) is below the maximum offset of the Pel model 33. The scan path is then divided up into a plurality of sections that span at least from Pel 0 to Pelm. It may be convenient to identify the sections by reference to a corresponding start and stop Pel at 410. For example, the data points from the Pel model 33 may be selected to define the start and stop Pels for each section. The length of a section is determined at 412. The length of a section can be expressed as a number of Pels in the scan direction between the stop and start Pels, and may be found for example, by subtracting the start Pel location from the stop Pel location. A curve/line approximation is then used to determine the process direction offsets of Pel locations in the section. For example, where a linear approximation is used, the slope of the section is computed at 414. The slope may be identified by the change in Pels in the Y (process) direction. That is: ΔY=Y(stop)−Y(start). The change in Pels in the Y direction defines the number of jumps that must occur to connect the start Pel to the stop Pel. For example, referring briefly to FIG. 10, an exemplary start Pel and corresponding stop Pel are plotted on a graph showing Pel locations along the X-axis, and process direction offsets along the Y-axis. As shown, the length of the exemplary section is 14 Pels and the slope is 4/14. Referring back to FIG. 9, the jumps are then distributed at 418 across the section according to a desired encoding. One exemplary way to distribute the jumps is to divide the current section into generally evenly spaced increments based upon the number of jumps in the current section. For example, the increment is computed at 416 by dividing the number of Pels in the current section (in the scan direction as determined at 412) by the number of jumps (represented by the change in Pels in the Y direction determined at 414). Also as illustrated, there is one jump per increment, however, other jump schemes may be implemented. Referring back to FIG. 10, an exemplary generally evenly spaced distribution of jumps is illustrated. As shown, the four jumps are spaced generally evenly across the section. Next, an encoding is generated. For example, given the above encoding (00-no jump, 01-jump down, 11 jump up), for each Pel location in the section where no jump occurs, that Pel location is assigned the two bit sequence 00 in the bit profile. Every Pel location that defines a jump up is encoded with a 11 in its corresponding location in the bit profile, and every Pel location that jumps down is encoded with a 01 in its corresponding location in the Pel profile 34. The process then continues until every section is processed. Any rounding scheme may be implemented to distribute the jumps so that they are generally spaced evenly. Referring back to FIG. 10, the two bit profile encoding is written above the jumps to illustrate how that Pel location is encoded. As a check, the microprocessor may optionally validate any implemented rules and declare an error if detected. The Bow Profile In order to perform hardware based image data warping, such as by the bow processor 20 shown in FIG. 1, it may be necessary to construct a bow profile 35 from an associated Pel profile 34. The Pel profile 34 differs from its corresponding bow profile 35 in that the Pel profile 34 defines how the bow correction data appears to the software executed by the microprocessor 18 in the system. The bow profile 35 on the other hand, defines the manner in which the same bow correction data appears to the hardware system of the bow processor 20. Referring back to FIG. 5, a Pel profile 34 is converted into a bow profile 35 at 322. For example, software may transform each Pel profile 34 into a series of entries in a source address list that defines the instructions for the bow processing logic. TABLE 3 Partial Source Address List/Vertical Strip Entry Bit Definition Bit 0 Bow 1 Bow Up; 0 Bow Down Direction Bits 24:16 Offset Offset in scans of where to read destination data Bit 63 65th bit Look ahead for the first bit of the next vertical Profile strip of the bow profile. If set, indicates a reversal of direction on the last bit of this column i.e. would be the second bit of a 11 instruction. If cleared, no effect. Bits Bow Bow Profile 127:64 Profile 0 - no jump 1 - jump one scan in the current direction 11 - reverse current direction and jump Left to Right - Cannot bow data more than every other bit The microprocessor 18 derives a bow profile 35 that is stored in the main system memory 16 for each Pel profile 34. The bow profiles 35 essentially translate their corresponding Pel profile 34 into a format suitable for processing by the bow processor 20. As one example, each Pel profile 34 is encoded into a corresponding bow profile 35 as part of a series of instructions, referred to generally as source address list entries. Each source address list entry encodes a portion, e.g., 64 Pel locations, of the Pel profile 34, and includes other operational data that the bow processor 20 may use during operation. The bow processor 20 and the bow profile 35, including corresponding source address list instructions executed thereby, are set out in greater detail in U.S. patent application Ser. No.______, Attorney Docket 2003-0839 entitled “Electronic Systems And Methods For Reducing Laser Beam Process Direction Position Errors”, which is already incorporated by reference herein. The relevant portions of an exemplary source address list entry bit definition are illustrated in Table 3. Each source address list entry is a 128-bit instruction. Of those 128 bits, bit 0 encodes the jump direction for that instruction, bits 24:16 encode the offset for that instruction, bit 63 encodes a 65th bit look ahead, and bits 127:64 encode 64 adjacent Pel locations in the corresponding Pel profile 34 where each bit corresponds to one Pel location of the Pel profile 34 and determines whether a jump should occur at that position. Bits 127:64 of each source address list entry thus represent a corresponding 64 Pel location section of the corresponding bow profile 35. As set out in Table 3, for each of the bits 127:64 in a source address list entry instruction, a value of 0 indicates no jump, a value of 1 indicates a jump one scan line in a current direction and the sequence 11 indicates a reversal of the current direction and a jump. Notably, in each source address list entry, only one bit of information is available to encode whether a jump is to occur at that given Pel location. Comparatively, in the Pel profile, two bits are assigned per Pel location to encode whether a jump is to occur. As such, to convert each Pel profile 34 to a corresponding bow profile 35, the microprocessor 18 breaks apart each Pel profile 34 into a plurality of (64 Pel location) sections and remaps the two-bit per Pel location format of the Pel profile 34 to one-bit per Pel location format in the associated source address list entry instructions. Note from the bow profile definition in Table 3 that in order to designate a change of direction, a sequence of “11” is required. However, the bow profile only stores one bit per column. In order to encode a direction change, the microprocessor 18 takes advantage of two rules. Namely, the bow processor 20 processes the bow profile 35 from left to right, and cannot jump on adjacent Pel locations. Thus if the bow processor 20 is to perform a jump at a first Pel location (column), it cannot perform a jump on the Pel location (column) immediately to the right thereof. As such, if the microprocessor 18 detects a jump in the Pel profile 34, the jump is recorded in the corresponding location of the source address list instruction, and the bit just to the right thereof is used to program whether a change in direction of the jump is to occur. This approach essentially implements a “look ahead” feature. For example, a bit in the bow profile (bits 127:64 of a source address list entry) just to the right of a valid jump (bit value of 1) may encode whether to maintain the current direction (bit value=0) or to reverse direction (bit value=1) as set out in the bow profile definition in Table 3. From a conceptual process, the microprocessor 18 traverses each Pel profile 34 starting at Pel 0 and works across to Pelm dividing the Pel profile 34 up into sections, e.g., 64-Pel locations per section. For each section, a Pel location that contains a value of 00 in the Pel profile 34 is simply mapped to a value of 0 in the corresponding location of the source address list entry. Each jump in the Pel profile 34 is mapped to a value of 1 in the corresponding location of the source address list entry with exceptions noted below. The first detected Pel location of the Pel profile 34 that encodes a jump in each section is also used to set the direction of the jump in the corresponding source address list entry. Recall that in the Pel profile 34, the direction of each jump is encoded with the jump. That is, each Pel location has a two-bit encoding where the value 11 encodes a jump up and 01 encodes a jump down. In the Bow profile of each source address list entry (bits 127:64), there is only one bit to encode whether to jump or not, so a single bit (bit 0) of the corresponding source address list entry encodes the initial direction of the jump. The software running on the microprocessor 18 determines the direction for bit 0 based upon the first detected jump within the Pel profile 34 that corresponds to the current source address list entry. For example, if the value of the first jump detected in a given section in the Pel profile 34 (corresponding to a given source address list entry) is “11” (a jump up), then bit 0 of that source address list entry is set to a value of 1 (direction=up). Similarly, if the value of the first jump detected in a given section in the Pel profile 34 is “01” (a jump down), then bit 0 of the source address list entry is set to a value of 0 (direction=down). For each detected jump, there can be no jump on the next adjacent Pel location to the right thereof due to the imposed rule described above. As such, the location to the right of a valid jump is used as a lookahead feature to determine whether to change directions, or continue to jump in the current direction. For every jump detected, a decision is made how to encode the jump. If the jump in the Pel profile 34 (up or down) is in the same direction as the previous jump, the value 0 is written to the bow profile 35 immediately to the right of the valid jump. Thus the value 0 serves as a look ahead to indicate to the bow processor 20 that no change in jump direction is required. If the direction of the jump in the Pel profile 34 is different from the preceding jump, the value of 1 is recorded to the right of a valid jump and serves as a look ahead to indicate that a reversal of direction is required when the bow processor 20 performs the jump. After processing a jump in the Pel profile 34, the Pel location to the right thereof is skipped over because that corresponding location has already been allocated as the look ahead in the associated bow profile 35. There is one exception to the above-described look ahead feature. If the last bit of the bow profile in the current source address list entry (e.g., bit 64 of a source address list entry) is a jump, i.e., has the value 1, there would be no way for the bow processor 20 to know whether a change in direction is required, unless the bow processor 20 also loaded the next successive source address list entry. To prevent the bow processor 20 from having to load two 128 bit instructions just to look ahead for 1 bit of information, the next consecutive bit in the bow profile, which is encoded into bit 127 of the next source address list entry is designated herein as the 65th bit (suggesting the 65th bit in an instruction that otherwise only holds 64 bits of bow data) and is encoded at bit position 63 in the current source address list entry. For example, if the last bit of the bow profile in the current source address list entry (bit 64) is 1 and the first bit of the bow profile (bit 127) in the next source address list entry is also 1 indicating a change in direction, the microprocessor sets the 65th bit (encoded at bit 63) of the current source address list entry to 1, otherwise, the 65th bit (bit location 63 in the corresponding source address list entry) is set to 0. This allows the bow processor 20 to know that a direction change is required, even when processing the last bit of the bow profile encoded in the current source address list entry. The microprocessor 18 must also toggle the next bit of the bow profile, encoded as the first bit (bit 127) of the next source address list entry to 0. This prevents the bow processor 20 from performing a jump on the first bit (bit 127) of the next source address list entry if that value is set to 1 (indicating a shift in direction of a valid jump encoded to the left thereof) when the next source address list entry is loaded. The use of the 65th bit (encoded into bit 63 of each source address list entry) is thus a look ahead into the next source address list entry. Bits 24:16 of the Source Address List entry indicate an offset that is used to determine where the bow processor 20 is to read data from to begin the read/modify/write operations necessary to bow the image data. The offset is set at the highest row in which the bow processor 20 will place image data when processing the corresponding source address list entry. Conceptually, the microprocessor 18 determines the maximum Y offset in the Pel profile 34, determines the maximum offset in the section of the Pel profile being processed for the corresponding source address list entry and subtracts the two to derive the source address list entry offset. As a simplified example, assume that each source address list entry includes only 22 bits to encode the bit profile so that the exemplary data in Table 2 corresponds to the Bow profile encoding of an entire source address list entry. The bow direction (bit 0 of the current source address list entry) is set to a value of 1 because the first detected jump when reading the values in Table 2 from left to right is a jump up (value=11). The offset is set to 1 because the highest row (determined by the data in columns 2 and 3) is one row from the top of Table 2. The 22-bit bow profile is encoded with 1-bit per Pel location as: “0010111010100101100001”. Note that the last bit is a jump. Therefore, the direction is encoded into the 65th bit (bit 63 of the corresponding source address list entry) as 1 indicating a change in direction. Note that the microprocessor 18 will also make sure that the first bit of the next bow profile (in the next source address list entry) is cleared as described above. Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. For example, the present invention may also be integrated with a printhead or like device in a copier, facsimile machine, etc. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to an electrophotographic imaging apparatus, and more particularly to systems and methods for characterizing laser beam process direction position errors. In electrophotography, a latent image is created on the surface of an electrostatically charged photoconductive drum by exposing select portions of the drum surface to laser light. Essentially, the density of the electrostatic charge on the surface of the drum is altered in areas exposed to a laser beam relative to those areas unexposed to the laser beam. The latent electrostatic image thus created is developed into a visible image by exposing the surface of the drum to toner, which contains pigment components and thermoplastic components. When so exposed, the toner is attracted to the drum surface in a manner that corresponds to the electrostatic density altered by the laser beam. Subsequently, a print medium such as paper is given an electrostatic charge opposite that of the toner and is pressed against the drum surface. As the medium passes the drum, the toner is pulled onto the surface thereof in a pattern corresponding to the latent image written to the drum surface. The medium then passes through a fuser that applies heat and pressure thereto. The heat causes constituents including the thermoplastic components of the toner to flow into the interstices between the fibers of the medium and the fuser pressure promotes settling of the toner constituents in these voids. As the toner is cooled, it solidifies and adheres the image to the medium. In order to produce an accurate representation of an image to be printed, it is necessary for the laser to write to the drum in a scan direction, which is defined by a straight line that is perpendicular to the direction of movement of the print media relative to the drum (the process direction). However, a number of optical elements including lenses and mirrors are typically required in the apparatus, including the printhead, to direct the laser beam towards the drum. Unavoidable imprecision in the shape and mounting of these optical elements with respect to the laser beam and/or drum can introduce process direction errors in the path of travel of the laser beam when writing across a scan line. It is also possible that a scan line written to the drum is not perpendicular to the movement of the print media due to laser misalignment and/or media misregistration. Under these conditions, there may be a skew associated with the printed image. The prior art has attempted to correct for laser beam process direction position errors by incorporating carefully manufactured optics that are precisely aligned. However, the increased precision required by each optical element adds significantly to its cost. Even with precisely manufactured and aligned optics, the degree to which laser beam process direction position errors may be corrected is limited by several factors, including component tolerances. Moreover, distortion of the laser beam optical scan path can occur even in a precisely aligned system due to component aging and/or operational influences such as temperature changes. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention overcomes the disadvantages of the prior art by providing systems and methods for characterizing laser beam process direction position errors in an electrophotographic device. Once the process direction position errors of a given laser beam have been characterized, bitmap image data may be adjusted or warped based upon the characterization in a manner that generally compensates therefore. According to an embodiment of the present invention, a table is stored in a memory device for each laser beam of an electrophotographic device. The table stores a plurality of data points that define measurements of the process direction position of the laser beam at several locations along a scan line. A laser scan path model of the laser beam is constructed from the plurality of data points to characterize the laser beam process direction position errors across the scan line. According to another embodiment of the present invention, a table is stored in a memory device for each laser beam of an electrophotographic device. The table stores a plurality of data points that define measurements of the process direction position of the laser beam at several locations along a scan line. A laser scan path model of the laser beam is constructed from the plurality of data points, and a pel profile is constructed from the laser scan path model. The pel profile is constructed in such a manner that it can be updated to account for changes in scan beam process direction errors due to registration and/or media misalignment corrections entered into the device, such as may be entered during a setup or calibration procedure. | 20040324 | 20080325 | 20050929 | 78986.0 | 0 | BRINICH, STEPHEN M | ALGORITHMS AND METHODS FOR DETERMINING LASER BEAM PROCESS DIRECTION POSITION ERRORS FROM DATA STORED ON A PRINTHEAD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,974 | ACCEPTED | Self-sealing cannula having integrated seals | The present invention relates to a surgical access device comprising an elongate tubular member having a working channel and an axis extending between a proximal end and a distal end, a septum seal integrally formed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member and distal to the septum seal, the zero seal being sized and configured to seal when no instrument is in place within the working channel of the tubular member, and the zero seal being coupled to the septum seal and having properties to float with the septum seal relative to the tubular member. The tubular member may be formed from an elastomeric material. The tubular member has a wall that may be rigid or semi-rigid, and the tubular member may be reinforced with a coil along a portion of the tubular member. The tubular member may include a distal, mechanically deployable shielding portion. The zero seal may be a duckbill seal constructed with one or more intersecting sealing portions. The duckbill seal may comprise of opposing lip portions separated by a slit portion. The opposing lip portions are coated with or attached to a soft or occlusive material. The occlusive material is one of Kraton, polyurethane or the like. The occlusive lip portions allow a surgical item such as a suture to extend through the slit portion without disrupting the seal. In one aspect, the tubular member and the septum seal are molded together as a single unit and the zero seal is then bonded or fused to the septum seal. In another aspect, the tubular member, the septum seal and the zero seal are all molded together or integrally formed as a single unit. The tubular member may further comprise flexibility enhancing features to allow the tubular member to flex in response to a motion of a surgical instrument within the working channel of the tubular member. | 1. A surgical access device, comprising: an elongate tubular member having a working channel and an axis extending between a proximal end and a distal end; a septum seal integrally formed at the distal end of the tubular member; and a zero seal disposed at the distal end of the tubular member and distal to the septum seal, the zero seal being sized and configured to seal when no instrument is in place within the working channel of the tubular member, and the zero seal being coupled to the septum seal and having properties to float with the septum seal relative to the tubular member. 2. The surgical access device of claim 1, wherein the tubular member is formed from an elastomeric material. 3. The surgical access device of claim 1, wherein the zero seal is a duckbill seal constructed with an intersecting sealing portion. 4. The surgical access device of claim 1, wherein the zero seal is a double duckbill seal constructed with two or more intersecting sealing portions 5. The surgical access device of claim 1, further comprising a retaining portion at the proximal end of the tubular member. 6. The surgical access device of claim 5, wherein the retaining portion is a flange or a ring. 7. The surgical access device of claim 1, wherein the tubular member and the septum seal are molded together as a single unit. 8. The surgical access device of claim 7, wherein the zero seal is bonded, fused or over-molded with the septum seal. 9. The surgical access device of claim 1, wherein the tubular member, the septum seal and the zero seal are molded together or integrally formed as a single unit. 10. The surgical access device of claim 1, wherein the tubular member further comprises flexibility enhancing features to allow the tubular member to flex in response to a motion of a surgical instrument within the working channel of the tubular member. 11. The surgical access device of claim 10, wherein the flexibility enhancing features are formed around the distal end of the tubular member. 12. The surgical access device of claim 10, wherein the flexibility enhancing features are formed along the tubular member. 13. The surgical access device of claim 10, wherein the flexibility enhancing features provide a floating motion to the septum seal and the zero seal. 14. The surgical access device of claim 1, further comprising a second septum seal disposed at or near the proximal end of the tubular member. 15. The surgical access device of claim of claim 14, wherein the second septum seal provides leak protection in the event that the septum seal is over-stressed or damaged. 16. The surgical access device of claim 14, further comprising a second zero seal disposed at or near the proximal end of the tubular member distal to the second septum seal, wherein the second zero seal is being sized and configured to seal when no instrument is in place within the working channel of the tubular member. 17. The surgical access device of claim 1, wherein the tubular member has at least one section that gradually tapers to facilitate placement of the access device through a body wall. 18. The surgical access device of claim 1, wherein the tubular member includes at least one region having a reduced wall section or thickness. 19. The surgical access device of claim 18, wherein the reduced thickness region is at or near the distal end of the tubular member. 20. The surgical access device of claim 1, further comprising a placement device for placing the access device. 21. The surgical access device of claim 20, wherein the placement device is an obturator operable to pierce or penetrate tissue. 22. The surgical access device of claim 20, wherein the placement device includes an elongate shaft having a proximal end, a mid-portion and a distal end. 23. The surgical access device of claim 20, wherein the proximal end includes a handle sized and configured to be held by a user. 24. The surgical access device of claim 20, wherein the mid-portion has a reduced profile and is sized and configured to extend through the tubular member. 25. The surgical access device of claim 20, wherein the distal end is shaped like an hourglass. 26. The surgical access device of claim 20, wherein the distal end comprises a tapered, cone-shaped member. 27. The surgical access device of claim 22, further comprising a venting lumen within the shaft of the placement device providing fluid communication between the distal end and the proximal end of the placement device. 28. The surgical access device of claim 20, further comprising an elastomeric shield member sized and configured to fit over the shaft of the placement device. 29. The surgical access device of claim 28, wherein as the placement device is withdrawn, the elastomeric shield member everts and is drawn into distal openings of the septum seal and the zero seal. 30. The surgical access device of claim 1, wherein the tubular member has a rigid or semi-rigid wall. 31. The surgical access device of claim 1, wherein the tubular member is reinforced with a coil along a portion of the tubular member. 32. The surgical access device of claim 31, wherein the reinforced portion terminates adjacent to a distal seal portion. 33. The surgical access device of claim 31, wherein the tubular member includes a distal, mechanically deployable shielding portion. 34. The surgical access device of claim 3, wherein the duckbill seal comprises opposing lip portions separated by a slit portion. 35. The surgical access device of claim 34, wherein the opposing lip portions are coated with or attached to a soft or occlusive material providing back pressure forcing the lip portions to close even when the duckbill seal is slightly open. 36. The surgical access device of claim 35, wherein the occlusive material is one of Kraton, polyurethane or the like. 37. The surgical access device of claim 35, wherein the occlusive lip portions allow a surgical item to extend through the slit portion without disrupting the seal. 38. The surgical access device of claim 37, wherein the surgical item is a surgical suture. 39. A method of placing a surgical access device across a body wall and into a body cavity, comprising the steps of: providing the surgical access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member; providing a placement device comprising an elongate shaft having a proximal end, a mid-portion and a distal end; inserting the placement device into the working channel of the tubular member with the distal end of the placement device extending beyond the distal end of the tubular member; and advancing the placement device and the tubular member through the body wall and into the body cavity. 40. The method of claim 39, further comprising the step of removing the placement device from the tubular member to open the working channel into the cavity. 41. The method of claim 40, further comprising the step of inserting a surgical instrument into the working channel of the tubular member to perform surgery within the cavity. 42. The method of claim 39, further comprising a rigid cannula having a proximal end and a distal end coaxially attached to the access device. 43. The method of claim 42, further comprising placing the septum seal and the zero seal in the cannula such that the septum seal and the zero seal extend distally from the distal end of the cannula. 44. A method for forming a one-piece surgical access device, said access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, comprising the steps of: placing the tubular member pre-form in a compression mold cavity having a proximal end and a distal end; placing the septum seal pre-form in the distal end of the compression mold cavity; and compressing the tubular member pre-form and the septum seal pre-form so as to mold said pre-forms into a preferred condition. 45. A method for forming a zero seal of a surgical access device, said access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and the zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, comprising the steps of: inserting slit-forming members into a mold core of the zero seal having lateral extremities; and sharpening the slit-forming members at the lateral extremities. 46. The method of claim 45, further comprising the step of tapering the slit-forming members at the lateral extremities to form an undercut slit or slit end portion. 47. The method of claim 46, further comprising the step of removing the core and slitting the terminal, lateral portion of the molded slit as the core is being removed. 48. A surgical access device, comprising: an elongate tubular member having a working channel and an axis extending between a proximal end and a distal end; a septum seal integrally formed at the proximal end of the tubular member; and a zero seal disposed at the proximal end of the tubular member and distal to the septum seal, the zero seal being sized and configured to seal when no instrument is in place within the working channel of the tubular member, and the zero seal being coupled to the septum seal and having properties to float with the septum seal relative to the tubular member. 49. The surgical access device of claim 48, wherein the tubular member and the septum seal are molded together as a single unit. 50. The surgical access device of claim 49, wherein the zero seal is bonded or fused to the septum seal. 51. The surgical access device of claim 48, wherein the tubular member, the septum seal and the zero seal are molded together or integrally formed as a single unit. 52. The surgical access device of claim 48, wherein the tubular member is formed from an elastomeric material. | BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to surgical access devices and, in particular, to a self-sealing cannula having integrated seals. 2. Discussion of the Relevant Art Access devices used in laparoscopic surgery generally include a cannula providing an operative channel that traverses a body wall and extends into an associated body cavity. The cannula is generally equipped with a proximal seal housing that remains external to the body cavity. The seal housing generally contains a combination of seal members sized and configured to maintain an elevated pressure within the body cavity. The most common seal construction within the seal housing comprises a first seal sized and configured to maintain a pressure differential when an instrument or tool is within the cannula and seal housing. This type of seal is commonly known as a septum seal. A typical septum seal is an elastomeric sheet or form with a hole or piercing generally at the center. A septum seal is generally dedicated to a range of instruments or tools, such as from five millimeters to twelve millimeters. To complete the seal system of a typical cannula seal-housing, a zero seal or zero seal is normally employed. Zero seals or zero seals are generally configured to be either open or closed and often rely on gradient pressure to form a complete seal. Examples of such zero seals or zero seals may include flap-valves, ball-zero seals and duckbill valves. The septum seal is preferably located proximal of the second seal so that an instrument or tool blocks the orifice in the septum before breaching the second seal or zero seal. The cannulas and seal housings are generally constructed of rigid materials. The most common material is plastic for disposable devices and metal for reusable devices. The seal housing extends for a distance proximally and is generally quite wider in diameter than the cannula. A typical cannula is approximately 100 mm long and a typical seal housing is 20-50 mm in length. The diameter of a typical cannula will accommodate instruments in the range of five millimeters to twelve millimeters. The diameter of the respective seal housings may range from twenty millimeters for a five-millimeter cannula to thirty millimeters for a twelve-millimeter cannula. Disadvantages of large seal housings include higher weight, cost and the limitation they place on the full use of surgical instruments passing through the seal housings. For instance, a surgical instrument having an overall shaft length of fifteen inches may have a reduced working length of about thirteen inches when placed through the seal housing of the prior art. That is, the working length is reduced by at least two inches. Moreover, there is the cost of complex seal housings to consider. In particular, they generally comprise a plurality of molded plastic components that address the complex nature of laparoscopic access devices. Accordingly, there is a need in the art for a surgical access device having integrated seals that does not require an external seal housing. SUMMARY OF THE INVENTION The present invention relates to a surgical access device comprising an elongate tubular member having a working channel and an axis extending between a proximal end and a distal end, a septum seal integrally formed at the distal end of the tubular member, and a zero seal or zero seal disposed at the distal end of the tubular member and distal to the septum seal, the zero seal being sized and configured to seal when no instrument is in place within the working channel of the tubular member, and the zero seal being coupled to the septum seal and having properties to float with the septum seal relative to the tubular member. The tubular member may be formed from an elastomeric material. The tubular member has a wall that may be rigid or semi-rigid. The tubular member may be reinforced with a coil along a portion of the tubular member. The tubular member may include a distal, mechanically deployable shielding portion. The zero seal may be a duckbill seal constructed with one or more intersecting sealing portions. The surgical access device may further comprise a retaining portion such as a flange or a ring at the proximal end of the tubular member. In one aspect of the invention, the tubular member and the septum seal are molded together as a single unit and the zero seal is bonded or fused to the septum seal. In another aspect, the tubular member, the septum seal and the zero seal are all molded together or integrally formed as a single unit. The tubular member may further comprise flexibility enhancing features to allow the tubular member to flex in response to a motion of a surgical instrument within the working channel of the tubular member. The flexibility enhancing features may be formed around the distal end of the tubular member or all along the tubular member. It is appreciated that the flexibility enhancing features provide a floating motion to the septum seal and the zero seal. The surgical access device may further comprise a second septum seal disposed at or near the proximal end of the tubular member. In this aspect of the invention, the second septum seal provides leak protection in the event that the septum seal is over-stressed or damaged. With this aspect of the invention, the surgical access device may further comprise a second zero seal disposed at or near the proximal end of the tubular member distal to the second septum seal. In another aspect of the invention, the tubular member may have at least one section that gradually tapers to facilitate placement of the access device through a body wall. The tubular member may also include at least one region having a reduced wall section or thickness. The reduced thickness region may be at or near the distal end of the tubular member. In yet another aspect of the invention, the surgical access device may further comprise a placement device for placing the access device. The placement device may be an obturator operable to pierce or penetrate tissue. The placement device of the invention includes an elongate shaft having a proximal end, a mid-portion and a distal end. In one aspect, the proximal end includes a handle sized and configured to be held by a user, the mid-portion has a reduced profile that is sized and configured to extend through the tubular member of the access device, and the distal end that is shaped like an hourglass. The distal end may comprise a tapered, cone-shaped member. The shaft may further comprise a venting lumen to provide fluid communication between the distal end and the proximal end of the placement device. The placement device may further comprise an elastomeric shield member sized and configured to fit over the shaft such that when the placement device is withdrawn, the elastomeric shield member everts and is drawn into distal openings of the septum seal and the zero seal. The duckbill seal of the zero seal may comprise of opposing lip portions separated by a slit portion. In this aspect, the opposing lip portions are coated with or attached to a soft or occlusive material. The occlusive material is one of Kraton, polyurethane or the like. It is appreciated that the occlusive lip portions allow a surgical item such as a suture to extend through the slit portion without disrupting the seal. In another aspect of the invention, a method of placing a surgical access device across a body wall and into a body cavity is disclosed, the method comprising the steps of: providing the surgical access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member; providing a placement device comprising an elongate shaft having a proximal end, a mid-portion and a distal end; inserting the placement device into the working channel of the tubular member with the distal end of the placement device extending beyond the distal end of the tubular member; and advancing the placement device and the tubular member through the body wall and into the body cavity. The method of placing the access device may further comprise the step of removing the placement device from the tubular member to open the working channel into the cavity. The method of placing the access device may further comprise the step of inserting a surgical instrument into the working channel of the tubular member to perform surgery within the cavity. In yet another aspect of the invention, a method of forming a one-piece surgical access device is disclosed, the access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, the method comprising the steps of: placing the tubular member pre-form in a compression mold cavity having a proximal end and a distal end; placing the septum seal pre-form in the distal end of the compression mold cavity; and compressing the tubular member pre-form and the septum seal pre-form so as to mold said pre-forms into a preferred condition. In yet another aspect of the invention, a method of forming a zero seal of a surgical access device is disclosed, the access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and the zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, the method comprising the steps of: inserting slit-forming members into a mold core of the zero seal having lateral extremities; and sharpening the slit-forming members at the lateral extremities. The method of forming the zero seal of the surgical access device may further comprise the step of tapering the slit-forming members at the lateral extremities to form an undercut slit or slit end portion. The method of forming the zero seal of the surgical access device may further comprise the step of removing the core and slitting the terminal, lateral portion of the molded slit as the core is being removed. These and other features and advantages of the invention will become more apparent with a discussion of preferred embodiments in reference to the associated drawings. DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a laparoscopic cannula and seal housing according to the prior art; FIG. 2 is a side view of a typical laparoscopic surgical procedure; FIG. 3 is a perspective view of a self-sealing laparoscopic cannula according to the invention; FIG. 4 is a side view of a laparoscopic surgical procedure employing the invention; FIG. 5 is a detail side view of the self-sealing laparoscopic cannula of the invention; FIG. 6 is a section side view of the self-sealing laparoscopic cannula of the invention with no surgical instrument in place; FIG. 7 is a section side view of the self-sealing laparoscopic cannula of the invention with a large surgical instrument in place; FIG. 8 is a section side view of the self-sealing laparoscopic cannula of the invention with a small surgical instrument in place; FIG. 9 is a distal end view of the self-sealing laparoscopic cannula of the invention; FIG. 10 is a proximal end view of the self-sealing laparoscopic cannula of the invention; FIG. 11 is a section side view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a proximally located seal system; FIG. 12 is a perspective view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a convoluted distal portion; FIG. 13 is a perspective view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a convoluted tubular cannula; FIG. 14 is a side section view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a distally located seal system and a redundant proximal septum seal; FIG. 15 is a side section view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a distally located seal system and a redundant proximal zero seal; FIG. 16 is a side section view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a distally located first seal and a redundant proximal septum seal and a redundant zero seal; FIG. 17 is a side section view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a tapered tubular body; FIG. 18 is perspective view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a more flexible distal portion; FIG. 19 is a side section view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a more flexible distal portion; FIGS. 20(A) and 20(B) illustrate perspective views of a placement tool for use in placing a self-sealing laparoscopic cannula of the invention; FIG. 21 is a side view of another embodiment of a placement tool for use in placing a self-sealing laparoscopic cannula of the invention; FIG. 22 is a side section view of yet another embodiment of a placement tool for use in placing a self-sealing laparoscopic cannula of the invention; FIG. 23 is a side view of a placement tool of the invention for use in a first condition; FIG. 24 is a side view of a placement tool of the invention for use in a second condition; FIG. 25 is a side view of a placement tool of the invention for use in a third condition; FIG. 26 is a side view of a placement tool of the invention for use in a fourth condition; FIG. 27 illustrates another method for molding a self-sealing laparoscopic cannula of the invention; FIG. 28 illustrates a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a rigid cannula; FIG. 29 illustrates a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a reinforced elastomeric cannula; FIGS. 30(A)-30(C) illustrate a placement device for use in placing a laparoscopic cannula in accordance with another embodiment of the invention having a rigid and movable shield; FIG. 31 illustrates a placement device for use in placing a laparoscopic cannula in accordance with another embodiment of the invention having a rigid and movable, collapsible shield; FIG. 32 illustrates a method for molding the open slits into a duckbill valve of the invention; FIG. 33 illustrates another condition of the molded duckbill slit of the invention; FIG. 34 illustrates another duckbill valve of the invention further comprising occlusive lip portions; FIG. 35 illustrates a double duckbill of the invention further comprising occlusive lip portions; FIG. 36 illustrates suture extending through the double duckbill of the invention; FIG. 37 is a perspective view of the double duckbill of the invention being incorporated within a rigid cannula and housing; FIG. 38 is a side section view of a rigid housing and cannula incorporating a self-sealing duckbill of the invention; FIG. 39 is an end view of a rigid housing and cannula incorporating a self-sealing duckbill of the invention; FIG. 40 is a side section view of a rigid housing and cannula incorporating a self-sealing duckbill of the invention with an instrument in place through the seal combination; FIG. 41 (A) is a perspective view of a self-sealing duckbill of the invention in an alternate embodiment as a seal module for use in a rigid housing; FIG. 41 (B) is a perspective view of a self-sealing duckbill of the invention in an alternate embodiment as a seal module in use in a rigid housing; and FIG. 42 is a perspective view of a self-sealing duckbill of the invention used within a standard trocar. DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE INVENTION Referring to FIG. 1, there is shown a laparoscopic surgical access device 10 of the prior art comprising a cannula 5 and a seal housing 15. Cannula 5 is sized and configured to pass through a body wall and into a body cavity. The seal housing is sized and configured to contain a seal combination that isolates the internal body cavity from the external environment. Positive pressure is provided to the internal body cavity so that the body wall is distended. FIG. 2 illustrates a common laparoscopic surgical procedure where access device 10 of the prior art has been placed through a body wall 20 and into a body cavity 21. It is clearly seen that the seal housing 15 of the prior art extends for an appreciable distance externally. Referring to FIG. 3, there is shown an access device 100 of the present invention having a generally elongate, tubular body 105, a proximal end 112 and a distal end 102. The elongate, tubular body 105 comprises an elastomeric cannula that is sized and configured to pass through a body wall 20 and into a body cavity 21. The proximal end 112 of the elongate, tubular body 105 may be open and may be constructed with an enlarged portion or flange ring 115. The distal end 102 of the elongate, tubular body 105 comprises a septum seal and a check valve or zero seal. Referring to FIG. 4, the access device 100 of the invention is seen in a laparoscopic surgical procedure where the elongate, tubular body 105 or cannula is placed through the body wall 20 and into the body cavity 21. The proximal end 112 of the elongate, tubular body 105 remains external to the body wall 20 and may be restricted from further entry into the body cavity 21 by the enlarged proximal flange or ring 115. The distal end 102 of the elongate, tubular body 105 further includes a seal system 103 comprising a check valve or zero seal within the body cavity 21 and serves to isolate the body cavity 21 from the external environment. The distal seal system 103 of the invention allows the body cavity 21 to be pressurized. With reference to FIGS. 5 and 6, an embodiment of the present invention is shown comprising a tubular, elongate body 105 having an outer surface 106 and an inner surface 107. The wall section is preferably thin and flexible. A first seal 140 and a second seal 120 of the seal system 103 are placed at the distal end 102 of the elongate, tubular body 105. In this embodiment, the first seal 140 is a septum seal that is molded or formed as the elongate, tubular body 105 is molded or formed so that the first seal 140 and the elongate, tubular body 105 are a single piece. A bonding feature 141 may be provided for attaching the first seal 140 to the second seal 120. The second seal 120 may comprise a duckbill seal that is constructed with two intersecting sealing portions. This construction is commonly referred to as a double duckbill seal. The zero seal operates to provide backflow prevention. The double duckbill construction is particularly useful in the invention because there are folds along several lines 121 and it is easily inserted through the body wall 20. In the present embodiment, the elongate, tubular body 105, a proximal retaining portion 115, the distal first seal 140 and the distal second seal 120 are all molded or formed in a monolithic or one-piece construction. Referring to FIGS. 7 and 8, the access device 100 of the present invention is shown with laparoscopic surgical instruments 200, 250 in place within a lumen or channel 122 of the access device 100. A large instrument 200, one having a large diameter nearly that of the inside diameter of the access diameter 100 itself, substantially fills the lumen 122 and substantially deforms the first seal 140 and second seal 120 as shown in FIG. 7. A small instrument 250, one having a diameter substantially less than the inside diameter of the access device 100 itself, slightly deforms the first seal 140 and the second seal 120 as shown in FIG. 8. Referring now to FIGS. 9 and 10, one appreciates the distal end 102 of the access device 100 as comprising a check valve or zero seal 120 formed as an intersection of two occlusive portions 136, 137 of a double duckbill 120. The proximal end view of FIG. 10 reveals that the second seal 140 is placed proximal of the first seal 120. The second seal 140 comprises a septum having an orifice 145 that is sized and configured to seal in conjunction with a specific range of usable instruments. Referring to FIG. 11, there is shown a section side view of a self-sealing laparoscopic cannula in accordance with another embodiment of the invention having a proximally located seal system. In particular, FIG. 11 illustrates a self-sealing laparoscopic cannula where a first seal 140 and a second seal 120 are molded as part of the elongate, tubular body 105. In this embodiment, the first seal 140 and the second seal 120 may be molded with, or attached near to, the proximal end 112 of the elongate, tubular body 105. Alternately, the seal members 140, 120 may be attached as a second operation by bonding or fusing to form the attachment. An enlargement 108 may be provided to allow deformed seals 140,120 material to move away from an instrument within the access device 100. Referring to FIGS. 12 and 13, there are shown perspective views of self-sealing laparoscopic cannulas in accordance with additional embodiments of the invention having a convoluted distal portion and a convoluted tubular cannula, respectively. Specifically, further embodiments of the invention are shown having a plurality of flexibility enhancing features 150 arranged upon the elongate, tubular body 105. As illustrated in FIG. 12, the flexibility enhancing features 150 allow the distal seal portion 103 of the elongate, tubular body 105 to flex in response to a motion of an instrument within the working channel or lumen of the elongate, tubular body 105. As an instrument is moved within the working channel, the distal end 102 moves appropriately without distorting the sensitive orifice 145 associated with the first seal 140. The motion associated with this configuration is referred to as “floating”. In this instance, the first and second seals 140, 120 associated with the distal end 102 of the elongate, tubular body 105 constitute “floating seals”. Referring to FIG. 13, a further embodiment contemplates an elongate, tubular body 105 having flexibility enhancing features 155 arranged along the entire length of the body 105. This results in an elongate body 105 that may be further elongated by stretching so that the diameter is reduced to facilitate introduction into the body cavity 21 through the body wall 20. Referring now to FIGS. 14, 15 and 16, the elongate, tubular body 105 is shown having a first seal 140 formed at the distal end 102. A second seal 120 is then attached over the first seal 140 to form a seal system 103 that is fluid tight between the exterior of the tubular body 105 and the interior 122 of the tubular body 105. The interior 122 of the tubular body 105 provides a working channel for the passage of surgical instruments into a pressurized body cavity 21. The first seal 140 is sized and configured to provide a fluid tight arrangement when an instrument is in place within the working channel 122. The second seal 120 is sized and configured to seal when no instrument is in place within the working channel 122. The first and second seals 140, 120 cooperate to provide a unique arrangement where there are strict requirements regarding friction, drag and durability. An alternate embodiment as shown in FIG. 14 contemplates the use of an additional first seal 140 at or near the proximal end 112 of the elongate, tubular body 105. The additional, proximal first seal 140 provides leak protection in the event that the primary first seal 140 is over-stressed or is damaged. With reference to FIG. 15, the elongate, tubular body 105 and integral, distal first seal 140 are shown. This embodiment further contemplates the placement of the second seal 120 at or near the proximal end 112 of the elongate, tubular body 112. Additionally, there is an enlargement 108 in the diameter of the elongate, tubular body 105 to accommodate displaced seal material 120 in the presence of a large instrument within the working channel 122 of the access device 100. Referring to FIG. 16, the elongate, tubular body 105 and integral, distal second seal 120 are shown. This embodiment further contemplates the placement of a redundant second seal 120 at or near the proximal end 112 of the elongate, tubular body 105. Additionally, a first seal 140 is placed at or near the proximal end 112 of the elongate, tubular body 105. In this arrangement, an instrument placed into the working channel 122 of the invention is first sealed against the proximal, first seal 140. Next, the instrument breaches the proximally located, redundant, second seal 120. Finally, the instrument breaches the distally placed, second seal 120. Referring to FIG. 17, the elongate, tubular body 105 is shown having a generally graduated or tapered wall sections 110, 111. The tapered wall provides a greater degree of flexibility in the region of the thin wall 111 than in the region of the thick wall 110. The gradual taper also facilitates placement of the access device 100 through a body wall 20. It may be seen from FIGS. 18 and 19 that the elongate, tubular body 105 may additionally comprise a region that has a reduced wall section or thickness 160. The reduced thickness region 160 is preferably located at or near the distal end 102 of the elongate, tubular body 105. This configuration permits the seal system 103 to “float” in response to the motion of an instrument within the operative working channel 122 of the access device 100. With reference to FIGS. 20(A) and 20(B), a device 300 for use in the placement of the elongate, tubular body 105 and seal system 103 is shown. The device 300 comprises an elongate shaft 310 having a proximal end 370, a mid-portion 311 and a distal end 320. The proximal end 370 is sized and configured to be held by a user and preferably comprises a handle 375. The mid-portion 311 is sized and configured to extend through the elongate, tubular body 105 and extend there-through. The distal end portion 325 of the placement device 300 is sized and configured to separate or penetrate the tissue of a body wall 20 and facilitate the passage of the tubular body 105 and seal system 103 there-through. FIGS. 21 and 22 illustrate side views of the placement device or obturator 300 for use in the placement of the elongate, tubular body 105 and seal system 103 of the invention. In particular, FIG. 21 illustrates the distal end 320 of placement device 300 having a first, conically tapered member 325 that begins with a point 326 and extends for a distance to a diameter approximately that of the inside diameter 107 of the elongate, tubular body 105 of the access device 100. Extending proximally from the largest diameter 363 of the distal first, conical portion 325, there is a second conical, continuing portion 330 that reduces a portion of the diameter of the placement device 300 to a preferred small diameter 340 for a distance 341 extending proximally. The small diameter 340 is sized and configured to pass through the seal system 103 of the invention without deforming the seal material to an unacceptable point while the placement device 300 is within the access device 100. The reduced diameter portion 340 extends for a distance 341 and subsequently begins to increase in diameter conically 350 to the full diameter of the elongate shaft 310. In a preferred embodiment, this third conical portion 350 matches the angle of the first seal member 140. In addition, a venting lumen 380 is provided within the shaft 310 of the placement device 300 providing fluid communication between the distal end 320 of the placement device and the proximal end 370 of the placement device 300. The distal, reduced diameter portion 339 of the placement device 300 resembles an hourglass. In a preferred embodiment, there is a retention feature 364 associated with the large diameter portion 363 of the distal portion 325 of the placement device 300. An elastomeric shield 360 is associated with the retention feature 364 and extends proximally for a distance sized and configured to cover the reduced diameter portion 339 of the placement device 300. The elastomeric shield 360 is sized and configured to fit tightly over the elongate shaft 310 of the placement device 300 for a short distance to prevent features of the second seal 120 from intercepting body wall 20 tissue as the access device 100 is urged through the body wall 20 and into the body cavity 21. The elongate, tubular body 105 and seal system 103 are placed over the placement device 300 of the invention so that the distal second seal 140 is at rest over the reduced diameter portion of the placement device. The elastomeric shield is stretched over the distal end 120 of the elongate, tubular body 105. The elastomeric shield 360 thus forms a smooth transition between the various components of the invention. Once proper placement of the access device 100 is confirmed, the placement device 300 may be withdrawn from the elongate, tubular body 105. The elastomeric sleeve 360 everts and follows the placement device 300 as it is withdrawn from the tubular body 105. Referring to FIGS. 23-26, the assembly of the invention is shown in the steps of placement. In a first condition as illustrated in FIG. 23, the placement device 300 is shown within the access tube 105 in a stored and ready for use condition. This first condition illustrates the smooth transitions between the distal end 320 of the placement device and the distal seal system 103 of the access device 100. Upon confirmed placement of the access device 100, the placement device 300 may be withdrawn from the access device 100. As the placement device 300 is withdrawn, the elastomeric shield member 360 everts and is drawn into the distal openings of the distal seal members 140,120 of the access device 100. Once the placement device 300 is fully withdrawn, it can be seen that the elastomeric shield member 360 is fully everted. The access device 100 is now ready for use. With reference to FIG. 27, a method for molding the elastomeric cannula 105 and seal system 103 of the present invention is shown comprising a cavity 420 and a core 440. The core 440 may comprise one or more mating portions 440a, 440b that allow the first seal 140 and the second seal 120 to be integrally formed with the elongate, tubular body or cannula 105. The first core portion forms the internal lumen 422 of the tubular body 105 and the distally facing surface 470 of the first seal or septum 140. A portion 430 of the first core 441 extends through the first seal or septum 140 and forms the orifice 145 there-through. A second portion 460 of the core 440 is removably attached to the extending portion 430 and forms the internal cavity 462 within the double duckbill seal or check valve 120. After an elastomeric material has flowed into the cavity 420 and around the first and second cores 440a, 440b, the first and second cores are disconnected so that the first core portion 440a may be removed proximally and the second core portion 440b may be removed distally through the intersecting slits in the distal end ribs of the double duckbill seal 120. In an alternate embodiment, the entire core 440 may comprise a one-piece construction that is removable proximally or distally from the elastomeric tubular body 105. FIG. 28 illustrates the present invention alternately comprising a rigid or semi-rigid thin-walled cannula 116 and a distally placed seal system 103 according to the present invention. The first and second seals 140, 120, respectively, may be formed as a single unit and subsequently attached to the distal end of the cannula 116 or, alternately, may be formed separately so that the first seal 140 is attached to the cannula and the second seal 120 is attached to the first seal. FIG. 29 illustrates an elastomeric cannula 101 that is reinforced so as to be substantially non-compressible radially. The reinforced cannula 101 may be preformed as a tube and subsequently placed into a compression or injection mold where the seal system 103 is formed at the distal end 102. A preferred embodiment contemplates the use of a metallic coil 152 as a reinforcement element along a portion of the elongate, tubular body 105 and terminating adjacent to the distal seal system 103. Alternately, a braided or woven reinforcement element 152 may be incorporated into the wall of the tubular body 105. FIGS. 30(A)-30(C) illustrate an alternate placement device 300 comprising an elongate shaft 310 having a proximal end 370 and a distal end 320. The proximal end further comprises a handle 375. The shaft 310 of the placement device 300 is sized and configured to be axially movable within the working channel 122 of the access device 100. A rigid or semi-rigid shielding member 380 is associated with the distal portion 339 of the placement device 300 that is sized and configured to provide smooth transitions between the various elements of the access device 100 and associated seal system 103. The distal end 320 of the placement device 300 is sized and configured to penetrate tissue and provide entry into a body cavity. The distal portion comprises a tapered, cone-shaped member 325. The rigid or semi-rigid shield 380 extends proximally from the widest diameter portion 381 of the tapered, cone-shaped member 325 for a distance. When the placement device is within the cannula 105 and seal system 103 of the invention, the proximal handle 375 is moved proximally to a first position where the internal shaft 310 locates the distal shield 380 to a first, proximal position 382. The first, proximal position 382 of the shield 380 covers the distal end 102 of the cannula 105 and seal system 103 of the invention. Once complete penetration of a body wall is confirmed, a spacer 390 may be removed that maintains a preferred storage relationship between the access device 100 and the placement device 300, then the proximal handle 375 may be urged forward to second position 391a so that the internal shaft 310 moves the distal tapered, cone-shaped member 325 and the associated shield 380 forward to expose the distal end 120 of the cannula 105 and seal system 103. The placement device 300 is then withdrawn from the cannula 105 and seal system 103. FIG. 31 illustrates a placement device for use in placing a laparoscopic cannula in accordance with another embodiment of the invention having a rigid and movable, collapsible shield. In particular, FIG. 31 illustrates a placement device 300 having a distal shielding portion 380 that may be mechanically deployed and un-deployed. The mechanical shield 380 comprises a first conical portion 325 sized and configured to penetrate body tissue, a second portion that extends rearward to shield adjacent seal system 103 and a deployment member 310 sized and configured to move the shield from a deployed condition to an un-deployed condition. In one embodiment, shield 380 may comprise a cylinder having a distal end 381 connected to the proximal portion of the penetrating portion 325 at the widest region or largest diameter. The cylindrical shield 380 may be formed of a spring like material and further having axial slits 383 arranged around the circumference that may have a first, at rest, condition and a second condition under the influence of a deployment member. This embodiment contemplates that the spring-shield 380 covers the distal end 102 of the cannula-seal member 103 in a slightly compressed condition. The shield 380 is urged forward after penetration of body tissue is confirmed so that the shield moves from the shielding position and reduces in diameter so that it may be withdrawn from the cannula-seal 103. The spring-shield comprises a cylinder that has a continuous circumference at a first end 381 and an interrupted circumference at a second end 382. The interrupted circumference resembles a plurality of extended fingers 384 extending from the continuous portion to the interrupted portion. The “at rest” condition of the interrupted portion may be configured so that the “fingers”. 384 exhibit an inward bias toward the axis of the cylinder. The inward bias facilitates rearward removal of the shield 380 from the cannula-seal 103. A handle 375 associated with the proximal end 370 of the placement device 300 allows the user to selectively extend the distal end 320 of the placement device 300 beyond the distal end 102 of the cannula-seal 103 for removal. Referring to FIG. 32, a method for molding the open slits into a duckbill valve 120 is shown where a core that defines the shape and size of the interior of the valve 120 is supplied with, at least, a thin blade 132 which extends beyond the core for a distance. Additionally the thin blade 132 makes contact with a portion of the mold cavity 420 that describes and forms the exterior of the duckbill valve 120 so that the molded material is prevented from flowing to form a closure. The lateral edges 131 of the thin blade 132 are sharpened to a fine edge so that the molded material does not form in an area or shape that prevents full closure of the slits 130 on presentation of back-flow. In one embodiment of the invention, the duckbill valve 120 has two crossing slits 130a, 130b arranged at right angles in a single plane. This is commonly referred to as a double duckbill valve. The crossing slits 130a, 130b are normally cut into the molded material after the valve has been formed. A method of manufacturing a double duckbill valve 120 comprises the insertion or placement of thin blades 132a, 132b or a thin-blade cross 133 at the sealing end of the valve mold core. The thin blades 132a, 132b or thin-blade cross 133 shut off the material flow during the molding process so that open slits are formed at the sealing end of the double duckbill valve 122. The lateral ends 131 are sharpened and slightly tapered so that there is no residual open portion 136 where the slits 130a, 130b terminate laterally. FIG. 33 shows the result of a condition where a residual opening 136 occurs in the molded valve 120. A thin blade 132 that is not sharpened at the lateral ends creates a non-sealing portion 136 where the blade or blades 132 terminate laterally. Referring to FIGS. 34, 35, duckbill valves 124, 120 are seen according to the present invention comprising opposing lip portions 126, 127 separated by slit portions 130. In this embodiment, the opposing lip portions 126, 127 are coated with or attached to a very soft and occlusive material 125. A material for the attached occlusive portions 125 may include silicone, Kraton, Polyurethane or the like. The soft, occlusive portions 125 of the opposing lips 126, 127 of the duckbill seals 120, 124 allow the duckbill seals to form a complete seal while an object is within the sealing portions of the duckbill. Normally, duckbill seals only seal when there is no object extending through the sealing lip portions or slits 130. With the occlusive sealing lip portions 126, 127 of the invention, a user may extend selected items through the seal without disrupting the seal. For instance, FIG. 36 illustrates that a surgeon may be able to tie a suture knot extra corporeally without losing internal gas pressure during a laparoscopic surgery where the present invention is used as an access device. The suture extensions 500, 501 may extend through the duckbill seal 120 so that they can be tied and subsequently pushed into place through the access device 100. The occlusive material 125 associated with the slits 130 in the duckbill valve 120 allows the valve to close fully even while certain items 500, 501 remain in the fluid path of the valve 120. With reference to FIGS. 37-41A, 41B, an alternate embodiment of the present invention is shown comprising a module 600 or combination of seal elements that are sized and configured to be used within a rigid seal housing 605 and cannula 5. This embodiment comprises a retaining portion 610, an extending portion 625, a first sealing portion 640 and a second sealing portion 620. The retaining portion 610 is sized and configured to fit within and be retained securely by a rigid seal housing 605. The extending portion 625 extends distally from the retaining portion 610 and preferably comprises a thin wall cylindrical structure or tube. A first seal 640 is associated with the distal end of the extending portion 625 that is sized and configured to receive a range of instruments there-through. A second seal 620 is associated with the distal portion of the first seal 640. The second seal is sized and configured to form a gas-tight zero seal. A module 600 or combination of seal elements constructed according to the present invention may be incorporated into a variety of rigid seal housings and provide the advantages of the present invention to otherwise deficient seal systems. Additionally, a cannula and seal combination contemplates a flexible cannula 105 within, and co-axial to, a rigid cannula 720 associated with a standard access device 700 and where the seal combination 103 associated with the present invention extends beyond the distal end 702 of the rigid cannula 720 for a distance so as to allow the seal combination 103 to expand sufficiently to allow passage of instruments therethrough. This configuration permits the use of the distal seal 103 in combination with a rigid cannula 720. Moreover, the rigid cannula 720 may be fitted over the flexible cannula 105 of the cannula and seal combination 100 of the present invention so that the features of the rigid cannula 720 may be utilized in combination with the advantages of the present invention. It will be understood that many other modifications can be made to the various disclosed embodiments without departing from the spirit and scope of the invention. For these reasons, the above description should not be construed as limiting the invention, but should be interpreted as merely exemplary of preferred embodiments. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention generally relates to surgical access devices and, in particular, to a self-sealing cannula having integrated seals. 2. Discussion of the Relevant Art Access devices used in laparoscopic surgery generally include a cannula providing an operative channel that traverses a body wall and extends into an associated body cavity. The cannula is generally equipped with a proximal seal housing that remains external to the body cavity. The seal housing generally contains a combination of seal members sized and configured to maintain an elevated pressure within the body cavity. The most common seal construction within the seal housing comprises a first seal sized and configured to maintain a pressure differential when an instrument or tool is within the cannula and seal housing. This type of seal is commonly known as a septum seal. A typical septum seal is an elastomeric sheet or form with a hole or piercing generally at the center. A septum seal is generally dedicated to a range of instruments or tools, such as from five millimeters to twelve millimeters. To complete the seal system of a typical cannula seal-housing, a zero seal or zero seal is normally employed. Zero seals or zero seals are generally configured to be either open or closed and often rely on gradient pressure to form a complete seal. Examples of such zero seals or zero seals may include flap-valves, ball-zero seals and duckbill valves. The septum seal is preferably located proximal of the second seal so that an instrument or tool blocks the orifice in the septum before breaching the second seal or zero seal. The cannulas and seal housings are generally constructed of rigid materials. The most common material is plastic for disposable devices and metal for reusable devices. The seal housing extends for a distance proximally and is generally quite wider in diameter than the cannula. A typical cannula is approximately 100 mm long and a typical seal housing is 20-50 mm in length. The diameter of a typical cannula will accommodate instruments in the range of five millimeters to twelve millimeters. The diameter of the respective seal housings may range from twenty millimeters for a five-millimeter cannula to thirty millimeters for a twelve-millimeter cannula. Disadvantages of large seal housings include higher weight, cost and the limitation they place on the full use of surgical instruments passing through the seal housings. For instance, a surgical instrument having an overall shaft length of fifteen inches may have a reduced working length of about thirteen inches when placed through the seal housing of the prior art. That is, the working length is reduced by at least two inches. Moreover, there is the cost of complex seal housings to consider. In particular, they generally comprise a plurality of molded plastic components that address the complex nature of laparoscopic access devices. Accordingly, there is a need in the art for a surgical access device having integrated seals that does not require an external seal housing. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention relates to a surgical access device comprising an elongate tubular member having a working channel and an axis extending between a proximal end and a distal end, a septum seal integrally formed at the distal end of the tubular member, and a zero seal or zero seal disposed at the distal end of the tubular member and distal to the septum seal, the zero seal being sized and configured to seal when no instrument is in place within the working channel of the tubular member, and the zero seal being coupled to the septum seal and having properties to float with the septum seal relative to the tubular member. The tubular member may be formed from an elastomeric material. The tubular member has a wall that may be rigid or semi-rigid. The tubular member may be reinforced with a coil along a portion of the tubular member. The tubular member may include a distal, mechanically deployable shielding portion. The zero seal may be a duckbill seal constructed with one or more intersecting sealing portions. The surgical access device may further comprise a retaining portion such as a flange or a ring at the proximal end of the tubular member. In one aspect of the invention, the tubular member and the septum seal are molded together as a single unit and the zero seal is bonded or fused to the septum seal. In another aspect, the tubular member, the septum seal and the zero seal are all molded together or integrally formed as a single unit. The tubular member may further comprise flexibility enhancing features to allow the tubular member to flex in response to a motion of a surgical instrument within the working channel of the tubular member. The flexibility enhancing features may be formed around the distal end of the tubular member or all along the tubular member. It is appreciated that the flexibility enhancing features provide a floating motion to the septum seal and the zero seal. The surgical access device may further comprise a second septum seal disposed at or near the proximal end of the tubular member. In this aspect of the invention, the second septum seal provides leak protection in the event that the septum seal is over-stressed or damaged. With this aspect of the invention, the surgical access device may further comprise a second zero seal disposed at or near the proximal end of the tubular member distal to the second septum seal. In another aspect of the invention, the tubular member may have at least one section that gradually tapers to facilitate placement of the access device through a body wall. The tubular member may also include at least one region having a reduced wall section or thickness. The reduced thickness region may be at or near the distal end of the tubular member. In yet another aspect of the invention, the surgical access device may further comprise a placement device for placing the access device. The placement device may be an obturator operable to pierce or penetrate tissue. The placement device of the invention includes an elongate shaft having a proximal end, a mid-portion and a distal end. In one aspect, the proximal end includes a handle sized and configured to be held by a user, the mid-portion has a reduced profile that is sized and configured to extend through the tubular member of the access device, and the distal end that is shaped like an hourglass. The distal end may comprise a tapered, cone-shaped member. The shaft may further comprise a venting lumen to provide fluid communication between the distal end and the proximal end of the placement device. The placement device may further comprise an elastomeric shield member sized and configured to fit over the shaft such that when the placement device is withdrawn, the elastomeric shield member everts and is drawn into distal openings of the septum seal and the zero seal. The duckbill seal of the zero seal may comprise of opposing lip portions separated by a slit portion. In this aspect, the opposing lip portions are coated with or attached to a soft or occlusive material. The occlusive material is one of Kraton, polyurethane or the like. It is appreciated that the occlusive lip portions allow a surgical item such as a suture to extend through the slit portion without disrupting the seal. In another aspect of the invention, a method of placing a surgical access device across a body wall and into a body cavity is disclosed, the method comprising the steps of: providing the surgical access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member; providing a placement device comprising an elongate shaft having a proximal end, a mid-portion and a distal end; inserting the placement device into the working channel of the tubular member with the distal end of the placement device extending beyond the distal end of the tubular member; and advancing the placement device and the tubular member through the body wall and into the body cavity. The method of placing the access device may further comprise the step of removing the placement device from the tubular member to open the working channel into the cavity. The method of placing the access device may further comprise the step of inserting a surgical instrument into the working channel of the tubular member to perform surgery within the cavity. In yet another aspect of the invention, a method of forming a one-piece surgical access device is disclosed, the access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and a zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, the method comprising the steps of: placing the tubular member pre-form in a compression mold cavity having a proximal end and a distal end; placing the septum seal pre-form in the distal end of the compression mold cavity; and compressing the tubular member pre-form and the septum seal pre-form so as to mold said pre-forms into a preferred condition. In yet another aspect of the invention, a method of forming a zero seal of a surgical access device is disclosed, the access device having an elongate tubular member including a working channel and an axis extending between a proximal end and a distal end, a septum seal disposed at the distal end of the tubular member, and the zero seal disposed at the distal end of the tubular member distal to the septum seal, the zero seal being coupled to the septum seal and having properties for floating with the septum seal relative to the tubular member, the method comprising the steps of: inserting slit-forming members into a mold core of the zero seal having lateral extremities; and sharpening the slit-forming members at the lateral extremities. The method of forming the zero seal of the surgical access device may further comprise the step of tapering the slit-forming members at the lateral extremities to form an undercut slit or slit end portion. The method of forming the zero seal of the surgical access device may further comprise the step of removing the core and slitting the terminal, lateral portion of the molded slit as the core is being removed. These and other features and advantages of the invention will become more apparent with a discussion of preferred embodiments in reference to the associated drawings. | 20040324 | 20121023 | 20050929 | 77817.0 | 0 | MEHTA, BHISMA | SELF-SEALING CANNULA HAVING INTEGRATED SEALS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,807,986 | ACCEPTED | Methods of isolating hydrajet stimulated zones | The present invention is directed to a method of isolating hydrajet stimulated zones from subsequent well operations. The method includes the step of drilling a wellbore into the subterranean formation of interest. Next, the wellbore may or may not be cased depending upon a number of factors including the nature and structure of the subterranean formation. Next, the casing, if one is installed, and wellbore are perforated using a high pressure fluid being ejected from a hydrajetting tool. A first zone of the subterranean formation is then fractured and stimulated. Next, the first zone is temporarily plugged or partially sealed by installing an isolation fluid into the wellbore adjacent to the one or more fractures and/or in the openings thereof, so that subsequent zones can be fractured and additional well operations can be performed. | 1. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) injecting a fracturing fluid into the one or more perforation tunnels so as to create at least one fracture along each of the one or more perforation tunnels; (c) plugging at least partially the one or more fractures in the first zone with an isolation fluid; and (d) repeating steps (a) and (b) in a second zone of the subterranean formation. 2. The method of completing a well according to claim 1, wherein the pressurized fluid being injected into the subterranean formation through the hydrajetting tool during step (a) comprises abrasive solids. 3. The method of completing a well according to claim 1, wherein the steps of injecting the fracturing fluid into the first and second zones is performed by the hydrajetting tool, which injects the fluid into the zones at a pressure above that required to fracture the formation. 4. The method of completing a well according to claim 3, further comprising a step of injecting an acidizing fluid into the one or more fractures, so as to etch the one or more fractures and thereby maintain conductivity within the one or more fractures at a later time. 5. The method of completing a well according to claim 1, further comprising the step of moving the hydrajetting tool to the second zone before step (c) is performed. 6. The method of completing a well according to claim 1, further comprising the step of moving the hydrajetting tool to the second zone after step (c) is performed. 7. The method of completing a well according to claim 1, wherein the isolation fluid comprises a solid or semi-solid material. 8. The method of completing a well according to claim 7, wherein the solid material comprises a proppant agent. 9. The method of completing a well according to claim 8, wherein the proppant agent comprises a material selected from the group consisting of silica, a ceramic, and a bauxite. 10. The method of completing a well according to claim 7, wherein the solid material comprises a material selected from the group consisting of paraffin beads, resin solids and PLA. 11. The method of completing a well according to claim 1, wherein the isolation fluid comprises a gel. 12. The method of completing a well according to claim 11, wherein the gel is a cross-linked gel. 13. The method of completing a well according to claim 12, wherein the cross-linked gel comprises PLA beads. 14. The method of completing a well according to claim 1, further comprising the step of removing the isolation fluid from the first zone. 15. The method of completing a well according to claim 14, wherein the step of removing the isolation fluid from the first zone is performed by circulating the isolation fluid out of the wellbore. 16. The method of completing a well according to claim 14, wherein the step of removing the isolation fluid from the first zone is performed by hydrajetting the isolation fluid out of the wellbore. 17. The method of completing a well according to claim 1, wherein each of the one or more fractures has an opening adjacent to the wellbore. 18. The method of completing a well according to claim 17, wherein the opening of each of the one or more fractures is filled with the isolation fluid. 19. The method of completing a well according to claim 17, wherein the isolation fluid fills at least a portion of the wellbore adjacent to each opening of the one or more fractures. 20. The method of completing a well according to claim 19, wherein the isolation fluid also fills the opening of the one or more fractures. 21. The method of completing a well according to claim 1, wherein the hydrajetting tool is kept stationary during step (a). 22. The method of completing a well according to claim 1, wherein the hydrajetting tool rotates during step (a) thereby cutting at least one slot into the first zone of the subterranean formation. 23. The method of completing a well according to claim 1, wherein the hydrajetting tool rotates and/or moves axially within the wellbore during step (a) so as to thereby cut a straight or helical slot into the first zone of the subterranean formation. 24. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) injecting a fracturing fluid into the one or more perforation tunnels so as to create at least one fracture along each of the one or more perforation tunnels; (c) plugging at least partially the one or more fractures in the first zone with isolation fluid; and (d) repeating steps (a) and (b) in a second zone of the subterranean formation. 25. The method of completing a well according to claim 24, wherein the steps of injecting the fracturing fluid into the first and second zones is performed by the hydrajetting tool, which injects the fluid into the zones at a pressure above that required to fracture the formation. 26. The method of completing a well according to claim 25, further comprising a step of injecting an acidizing fluid into the one or more fractures, so as to etch the one or more and thereby maintain conductivity within the one or more fractures at a later time. 27. The method of completing a well according to claim 25, further comprising the step of moving the hydrajetting tool to the second zone before step (c) is performed. 28. The method of completing a well according to claim 25, further comprising the step of moving the hydrajetting tool to the second zone after step (c) is performed. 29. The method of completing a well according to claim 24, wherein the isolation fluid comprises a solid material. 30. The method of completing a well according to claim 29, wherein the solid material comprises a proppant agent. 31. The method of completing a well according to claim 30, wherein the proppant agent comprises a material selected from the group consisting of silica, a ceramic, and a bauxite. 32. The method of completing a well according to claim 29, wherein the solid material comprises a material selected from the group consisting of paraffin beads, resin solids and PLA. 33. The method of completing a well according to claim 24, wherein the isolation fluid comprises a gel. 34. The method of completing a well according to claim 33, wherein the gel is a cross-linked gel. 35. The method of completing a well according to claim 34, wherein the cross-linked gel comprises PLA beads. 36. The method of completing a well according to claim 35, wherein the PLA beads decompose into acid and fluidizes the gel. 37. The method of completing a well according to claim 24, further comprising the step of removing the isolation fluid from the first zone. 38. The method of completing a well according to claim 37, wherein the step of removing the isolation fluid from the first zone is performed by circulating the isolation fluid out of the wellbore. 39. The method of completing a well according to claim 37, wherein the step of removing the isolation fluid from the first zone is performed by hydrajetting the isolation fluid out of the wellbore. 40. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) initiating one or more fractures in the first zone of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels through the hydrajetting tool; (c) moving the hydrajetting tool up hole; (d) pumping additional fracturing fluid into the one or more fractures in the first zone through a wellbore annulus in which the hydrajetting tool is disposed so as to propagate the fracture; (e) plugging at least partially the one or more fractures in the first zone with an isolation fluid; and (f) repeating steps (a) through (d) in a second zone of the subterranean formation. 41. The method of completing a well according to claim 40, wherein additional fracturing fluid is pumped through the annulus to assist the hydrajetting tool initiate the fracture in the subterranean formation. 42. The method of completing a well according to claim 40, wherein the one or more fractures are formed in a horizontal or deviated portion of the wellbore. 43. The method of completing a well according to claim 40, wherein the one or more fractures are formed in a vertical portion of the wellbore. 44. The method of completing a well according to claim 40, wherein the hydrajetting tool is kept stationary during step (a). 45. The method of completing a well according to claim 40, wherein the hydrajetting tool rotates during step (a) thereby cutting at least one slot into the first zone of the subterranean formation. 46. The method of completing a well according to claim 45, wherein the hydrajetting tool rotates and/or moves axially within the wellbore during step (a) so as to thereby cut a straight or helical slot into the first zone of the subterranean formation. 47. The method of completing a well according to claim 40, wherein the fracturing fluid is pumped down the annulus as soon as the one or more fractures are initiated. 48. The method of completing a well according to claim 40, wherein any cuttings left in the annulus from step (a) are pumped into the fracture during step (d). 49. The method of completing a well according to claim 40, wherein steps (c) and (e) are performed simultaneously. 50. The method of completing a well according to claim 49, wherein the rate of fluid ejected from the hydrajetting tool decreases during the performance of step (c). 51. The method of completing a well according to claim 40, further comprising the step of pumping acid into the wellbore to activate or dissolve the isolation fluid after all of the desired fractures have been formed. 52. The method of completing a well according to claim 40, further comprising the step of circulating the isolation fluid back to the surface after all of the desired fractures have been formed. 53. The method of completing a well according to claim 40, further comprising the step of pumping nitrogen into the wellbore to flush out the wellbore and remove it of the isolation fluid and other fluids and materials that may be left in the wellbore. 54. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) initiating one or more fractures in the first zone of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels through the hydrajetting tool; (c) pumping additional fracturing fluid into the one or more fractures in the first zone through a wellbore annulus in which the hydrajetting tool is disposed so as to propagate the one or more fractures; (d) simultaneous with step (c) moving the hydrajetting tool up hole; and (e) repeating steps (a) through (d) in a second zone of the subterranean formation. 55. The method of completing a well according to claim 54, wherein the rate of the fracturing fluid being ejected from the hydrajetting tool is decreased during step (d). 56. The method of completing a well according to claim 54, wherein any cuttings left in the annulus from step (a) are pumped into the fracture during step (c). 57. The method of completing a well according to claim 54, wherein the hydrajetting tool is kept stationary during step (a). 58. The method of completing a well according to claim 54, wherein the hydrajetting tool rotates during step (a) thereby cutting at least one slot into the first zone of the subterranean formation. 59. The method of completing a well according to claim 54, wherein the hydrajetting tool rotates and/or moves axially within the wellbore during step (a) so as to thereby cut a straight or helical slot into the first zone of the subterranean formation. 60. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) initiating one or more fractures in the first zone of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels through the hydrajetting tool; (c) pumping additional fracturing fluid into the one or more fractures in the first zone through a wellbore annulus in which the hydrajetting tool is disposed so as to propagate the one or more fractures; (d) simultaneous with step (c) moving the hydrajetting tool up hole; (e) terminating step (c); and (f) repeating steps (a)-(c) in a second zone of the subterranean formation. 61. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a perforating fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) fracturing the first zone of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels; (c) perforating a second zone in the subterranean formation by injecting the perforation fluid through the hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels in the second zone; (d) fracturing the second zone of the subterranean formation by injecting the fracturing fluid into the one or more perforation tunnels; and (e) pumping enough fracturing fluid into the wellbore during step (d) to plug the fractures in the first zone. 62. The method of completing a well according to claim 61, wherein the fracturing fluid comprises a base fluid, sand, and an additional additive selected from the group consisting of an adhesive and a consolidation agent. 63. The method of completing a well according to claim 62, wherein the fracturing fluid comprises both the adhesive and the consolidation agent. 64. The method of completing a well according to claim 63, wherein the adhesive is SANDWEDGE conductivity enhancer and the consolidation agent is EXPEDITE consolidation agent. 65. A method of completing a well in a subterranean formation, comprising the steps of: (a) perforating a first zone in the subterranean formation by injecting a perforating fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels; (b) initiating a fracture in the one or more perforation tunnels by pumping a fracturing fluid through the hydrajetting tool; (c) injecting additional fracturing fluid into the one or more fractures through both the hydrajetting tool and a wellbore annulus in which the hydrajetting tool is disposed, so as to propagate the one or more fractures; (d) plugging at least partially the one or more fractures in the first zone with an isolation fluid; (e) moving the hydrajetting tool away from the first zone; and (f) repeating steps (a) through (c) for a second zone. 66. The method of completing a well according to claim 66, wherein the step of moving the hydrajetting tool away from the first zone comprises moving the hydrajetting tool up hole. 67. The method of completing a well according to claim 66, wherein the step of moving the hydrajetting tool away from the first zone comprises moving the hydrajetting tool down hole. | FIELD OF THE INVENTION The present invention relates generally to well completion operations, and more particularly methods of stimulation and subsequent isolation of hydrajet stimulated zones from subsequent jetting or stimulation operations, so as to minimize the loss of completion/stimulation fluids during the subsequent well jetting or stimulation operations. BACKGROUND OF THE INVENTION In some wells, it is desirable to individually and selectively create multiple fractures having adequate conductivity, usually a significant distance apart along a wellbore, so that as much of the hydrocarbons in an oil and gas reservoir as possible can be drained/produced into the wellbore. When stimulating a reservoir from a wellbore, especially those that are highly deviated or horizontal, it is difficult to control the creation of multi-zone fractures along the wellbore without cementing a liner to the wellbore and mechanically isolating the zone being fractured from previously fractured zones or zones not yet fractured. Traditional methods to create fractures at predetermined points along a highly deviated or horizontal wellbore vary depending on the nature of the completion within the lateral (or highly deviated) section of the wellbore. Only a small percentage of the horizontal completions during the past 15 or more years used a cemented liner type completion; most used some type of non-cemented liner or a bare openhole section. Furthermore, many wells with cemented liners in the lateral were also completed with a significant length of openhole section beyond the cemented liner section. The best known way to achieve desired hydraulic fracturing isolation/results is to cement a solid liner in the lateral section of the wellbore, perform a conventional explosive perforating step, and then perform fracturing stages along the wellbore using some technique for mechanically isolating the individual fractures. The second most successful method involves cementing a liner and significantly limiting the number of perforations, often using tightly grouped sets of perforations, with the number of total perforations intended to create a flow restriction giving a back-pressure of about 100 psi or more, due to fluid flow restriction based on the wellbore injection rate during stimulation, with some cases approaching 1000 psi flow resistance. This technology is generally referred to as “limited entry” perforating technology. In one conventional method, after the first zone is perforated and fractured, a sand plug is installed in the wellbore at some point above the fracture, e.g., toward the heel. The sand plug restricts any meaningful flow to the first zone fracture and thereby limits the loss of fluid into the formation, while a second upper zone is perforated and fracture stimulated. One such sand plug method is described in SPE 50608. More specifically, SPE 50608 describes the use of coiled tubing to deploy explosive perforating guns to perforate the next treatment interval while maintaining well control and sand plug integrity. The coiled tubing and perforating guns were removed from the well and then the next fracturing stage was performed. Each fracturing stage was ended by developing a sand plug across the treatment perforations by increasing the sand concentration and simultaneously reducing pumping rates until a bridge was formed. The paper describes how increased sand plug integrity could be obtained by performing what is commonly known in the cementing services industry as a “hesitation squeeze” technique. A drawback of this technique, however, is that it requires multiple trips to carry out the various stimulation and isolation steps. More recently, Halliburton Energy Services, Inc. has introduced and proven the technology for using hydrajet perforating, jetting while fracturing, and co-injection down the annulus. In one method, this process is generally referred to by Halliburton as the SURGIFRAC process or stimulation method and is described in U.S. Pat. No. 5,765,642, which is incorporated herein by reference. The SURGIFRAC process has been applied mostly to horizontal or highly deviated wellbores, where casing the hole is difficult and expensive. By using this hydrajetting technique, it is possible to generate one or more independent, single plane hydraulic fractures; and therefore, highly deviated or horizontal wells can be often completed without having to case the wellbore. Furthermore, even when highly deviated or horizontal wells are cased, hydrajetting the perforations and fractures in such wells generally result in a more effective fracturing method than using traditional explosive charge perforation and fracturing techniques. Thus, prior to the SURGIFRAC technique, methods available were usually too costly to be an economic alternative, or generally ineffective in achieving stimulation results, or both. SUMMARY OF THE INVENTION The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the exemplary embodiments, which follows. The present invention is directed to a method of completing a well using a hydrajetting tool and subsequently plugging or partially sealing the fractures in each zone with an isolation fluid. In accordance with the present invention, the hydrajetting tool can perform one or more steps, including but not limited to, the perforating step, the perforating and fracture steps, and the perforating, fracture and isolation steps. More specifically, the present invention is directed to a method of completing a well in a subterranean formation, comprising the following steps. First, a wellbore is drilled in the subterranean formation. Next, depending upon the nature of the formation, the wellbore is lined with a casing string or slotted liner. Next, a first zone in the subterranean formation is perforated by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels. This fluid may or may not contain solid abrasives. Following the perforation step, the formation is fractured in the first zone by injecting a fracturing fluid into the one or more perforation tunnels, so as to create at least one fracture along each of the one or more perforation tunnels. Next, the one or more fractures in the first zone are plugged or partially sealed by installing an isolation fluid into the wellbore adjacent to the fractures and/or inside the openings of the fractures. In at least one embodiment, the isolation fluid has a greater viscosity than the fracturing fluid. Next, a second zone of the subterranean formation is perforated and fractured. If it is desired to fracture additional zones of the subterranean formation, then the fractures in the second zone are plugged or partially sealed by the same method, namely, installing an isolation fluid into the wellbore adjacent to the fractures and/or inside the openings of the fractures. The perforating, fracturing and sealing steps are then repeated for the additional zones. The isolation fluid can be removed from fractures in the subterranean formation by circulating the fluid out of the fractures, or in the case of higher viscosity fluids, breaking or reducing the fluid chemically or hydrajetting it out of the wellbore. Other exemplary methods in accordance with the present invention are described below. An advantage of the present invention is that the tubing string can be inside the wellbore during the entire treatment. This reduces the cycle time of the operation. Under certain conditions the tubing string with the hydrajetting tool or the wellbore annulus, whichever is not being used for the fracturing operation, can also be used as a real-time BHP (Bottom Hole Pressure) acquisition tool by functioning as a dead fluid column during the fracturing treatment. Another advantage of the invention is the tubing string provides a means of cleaning the wellbore out at anytime during the treatment, including before, during, after, and in between stages. Tubulars can consist of continuous coiled tubing, jointed tubing, or combinations of coiled and jointed tubing. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, which: FIG. 1A is a schematic diagram illustrating a hydrajetting tool creating perforation tunnels through an uncased horizontal wellbore in a first zone of a subterranean formation. FIG. 1B is a schematic diagram illustrating a hydrajetting tool creating perforation tunnels through a cased horizontal wellbore in a first zone of a subterranean formation. FIG. 2 is a schematic diagram illustrating a cross-sectional view of the hydrajetting tool shown in FIG. 1 forming four equally spaced perforation tunnels in the first zone of the subterranean formation. FIG. 3 is a schematic diagram illustrating the creation of fractures in the first zone by the hydrajetting tool wherein the plane of the fracture(s) is perpendicular to the wellbore axis. FIG. 4A is a schematic diagram illustrating one embodiment according to the present invention wherein the fractures in the first zone are plugged or partially sealed with an isolation fluid delivered through the wellbore annulus after the hydrajetting tool has moved up hole. FIG. 4B is a schematic diagram illustrating another embodiment according to the present invention wherein the fractures in the first zone are plugged or partially sealed with an isolation fluid delivered through the wellbore annulus before the hydrajetting tool has moved up hole. FIG. 4C is a schematic diagram illustrating another embodiment according to the present invention wherein the isolation fluid plugs the inside of the fractures rather than the wellbore alone. FIG. 4D is a schematic diagram illustrating another embodiment according to the present invention wherein the isolation fluid plugs the inside of the fractures and at least part of the wellbore. FIG. 5 is a schematic diagram illustrating another embodiment according to the present invention wherein the isolation fluid is delivered into the wellbore through the hydrajetting tool. FIG. 6 is a schematic diagram illustrating the creation of fractures in a second zone of the subterranean formation by the hydrajetting tool after the first zone has been plugged. FIG. 7 is a schematic diagram illustrating one exemplary method of removing the isolation fluid from the wellbore in the subterranean formation by allowing the isolation fluid to flow out of the well with production. FIGS. 8A and 8B are schematic diagrams illustrating two other exemplary methods of removing the isolation fluid from the fractures in the subterranean formation. FIGS. 9A-9D illustrate another exemplary method of fracturing multiple zones in a subterranean formation and plugging or partially sealing those zones in accordance with the present invention. FIGS. 10A-C illustrate yet another exemplary method of fracturing multiple zones in a subterranean formation and plugging or partially sealing those zones in accordance with the present invention. FIGS. 11A and 11B illustrate operation of a hydrajetting tool for use in carrying out the methods according to the present invention. DETAILED DESCRIPTION OF THE INVENTION The details of the method according to the present invention will now be described with reference to the accompanying drawings. First, a wellbore 10 is drilled into the subterranean formation of interest 12 using conventional (or future) drilling techniques. Next, depending upon the nature of the formation, the wellbore 10 is either left open hole, as shown in FIG. 1A, or lined with a casing string or slotted liner, as shown in FIG. 1B. The wellbore 10 may be left as an uncased open hole if, for example, the subterranean formation is highly consolidated or in the case where the well is a highly deviated or horizontal well, which are often difficult to line with casing. In cases where the wellbore 10 is lined with a casing string, the casing string may or may not be cemented to the formation. The casing in FIG. 1B is shown cemented to the subterranean formation. Furthermore, when uncemented, the casing liner may be either a slotted or preperforated liner or a solid liner. Those of ordinary skill in the art will appreciate the circumstances when the wellbore 10 should or should not be cased, whether such casing should or should not be cemented, and whether the casing string should be slotted, preperforated or solid. Indeed, the present invention does not lie in the performance of the steps of drilling the wellbore 10 or whether or not to case the wellbore, or if so, how. Furthermore, while FIGS. 2 through 10 illustrate the steps of the present invention being carried out in an uncased wellbore, those of ordinary skill in the art will recognize that each of the illustrated and described steps can be carried out in a cased or lined wellbore. The method can also be applied to an older well bore that has zones that are in need of stimulation. Once the wellbore 10 is drilled, and if deemed necessary cased, a hydrajetting tool 14, such as that used in the SURGIFRAC process described in U.S. Pat. No. 5,765,642, is placed into the wellbore 10 at a location of interest, e.g., adjacent to a first zone 16 in the subterranean formation 12. In one exemplary embodiment, the hydrajetting tool 14 is attached to a coil tubing 18, which lowers the hydrajetting tool 14 into the wellbore 10 and supplies it with jetting fluid. Annulus 19 is formed between the coil tubing 18 and the wellbore 10. The hydrajetting tool 14 then operates to form perforation tunnels 20 in the first zone 16, as shown in FIG. 1. The perforation fluid being pumped through the hydrajetting tool 14 contains a base fluid, which is commonly water and abrasives (commonly sand). As shown in FIG. 2, four equally spaced jets (in this example) of fluid 22 are injected into the first zone 16 of the subterranean formation 12. As those of ordinary skill in the art will recognize, the hydrajetting tool 14 can have any number of jets, configured in a variety of combinations along and around the tool. In the next step of the well completion method according to the present invention, the first zone 16 is fractured. This may be accomplished by any one of a number of ways. In one exemplary embodiment, the hydrajetting tool 14 injects a high pressure fracture fluid into the perforation tunnels 20. As those of ordinary skill in the art will appreciate, the pressure of the fracture fluid exiting the hydrajetting tool 14 is sufficient to fracture the formation in the first zone 16. Using this technique, the jetted fluid forms cracks or fractures 24 along the perforation tunnels 20, as shown in FIG. 3. In a subsequent step, an acidizing fluid may be injected into the formation through the hydrajetting tool 14. The acidizing fluid etches the formation along the cracks 24 thereby widening them. In another exemplary embodiment, the jetted fluid carries a proppant into the cracks or fractures 24. The injection of additional fluid extends the fractures 24 and the proppant prevents them from closing up at a later time. The present invention contemplates that other fracturing methods may be employed. For example, the perforation tunnels 20 can be fractured by pumping a hydraulic fracture fluid into them from the surface through annulus 19. Next, either and acidizing fluid or a proppant fluid can be injected into the perforation tunnels 20, so as to further extend and widen them. Other fracturing techniques can be used to fracture the first zone 16. Once the first zone 16 has been fractured, the present invention provides for isolating the first zone 16, so that subsequent well operations, such as the fracturing of additional zones, can be carried out without the loss of significant amounts of fluid. This isolation step can be carried out in a number of ways. In one exemplary embodiment, the isolation step is carried out by injecting into the wellbore 10 an isolation fluid 28, which may have a higher viscosity than the completion fluid already in the fracture or the wellbore. In one embodiment, the isolation fluid 28 is injected into the wellbore 10 by pumping it from the surface down the annulus 19. More specifically, the isolation fluid 28, which is highly viscous, is squeezed out into the annulus 19 and then washed downhole using a lower viscosity fluid. In one implementation of this embodiment, the isolation fluid 28 is not pumped into the wellbore 10 until after the hydrajetting tool 14 has moved up hole, as shown in FIG. 4A. In another implementation of this embodiment, the isolation fluid 28 is pumped into the wellbore 10, possibly at a reduced injection rate than the fracturing operation, before the hydrajetting tool 14 has moved up hole, as shown in FIG. 4B. If the isolation fluid is particularly highly viscous or contains a significant concentration of solids, preferably the hydrajetting tool 14 is moved out of the zone being plugged or partially sealed before the isolation fluid 28 is pumped downhole because the isolation fluid may impede the movement of the hydrajetting tool within the wellbore 10. In the embodiments shown in FIGS. 4A and 4B, the isolation fluid is shown in the wellbore 10 alone. Alternatively, the isolation fluid could be pumped into the jetted perforations and/or the opening of the fractures 24, as shown in FIG. 4C. In still another embodiment, the isolation fluid is pumped both in the opening of the fractures 24 and partially in the wellbore 10, as shown in FIG. 4D. In another exemplary embodiment of the present invention, the isolation fluid 28 is injected into the wellbore 10 adjacent the first zone 16 through the jets 22 of the hydrajetting tool 14, as shown in FIG. 5. In this embodiment, the chemistry of the isolation fluid 28 must be selected such that it does not substantially set up until after in has been injected into the wellbore 10. In another exemplary embodiment, the isolation fluid 28 is formed of a fluid having a similar chemical makeup as the fluid resident in the wellbore during the fracturing operation. The fluid may have a greater viscosity than such fluid, however. In one exemplary embodiment, the wellbore fluid is mixed with a solid material to form the isolation fluid. The solid material may include natural and man-made proppant agents, such as silica, ceramics, and bauxites, or any such material that has an external coating of any type. Alternatively, the solid (or semi-solid) material may include paraffin, encapsulated acid or other chemical, or resin beads. In another exemplary embodiment, the isolation fluid 28 is formed of a highly viscous material, such as a gel or cross-linked gel. Examples of gels that can be used as the isolation fluid include, but are not limited to, fluids with high concentration of gels such as Xanthan. Examples of cross-linked gels that can be used as the isolation fluid include, but are not limited to, high concentration gels such as Halliburton's DELTA FRAC fluids or K-MAX fluids. “Heavy crosslinked gels” could also be used by mixing the crosslinked gels with delayed chemical breakers, encapsulated chemical breakers, which will later reduce the viscosity, or with a material such as PLA (poly-lactic acid) beads, which although being a solid material, with time decomposes into acid, which will liquefy the K-MAX fluids or other crosslinked gels. After the isolation fluid 28 is delivered into the wellbore 10 adjacent the fractures 24, a second zone 30 in the subterranean formation 12 can be fractured. If the hydrajetting tool 14 has not already been moved within the wellbore 10 adjacent to the second zone 30, as in the embodiment of FIG. 4A, then it is moved there after the first zone 16 has been plugged or partially sealed by the isolation fluid 28. Once adjacent to the second zone 30, as in the embodiment of FIG. 6, the hydrajetting tool 14 operates to perforate the subterranean formation in the second zone 30 thereby forming perforation tunnels 32. Next, the subterranean formation 12 is fractured to form fractures 34 either using conventional techniques or more preferably the hydrajetting tool 14. Next, the fractures 34 are extended by continued fluid injection and using either proppant agents or acidizing fluids as noted above, or any other known technique for holding the fractures 34 open and conductive to fluid flow at a later time. The fractures 34 can then be plugged or partially sealed by the isolation fluid 28 using the same techniques discussed above with respect to the fractures 24. The method can be repeated where it is desired to fracture additional zones within the subterranean formation 12. Once all of the desired zones have been fractured, the isolation fluid 28 can be recovered thereby unplugging the fractures 24 and 34 for subsequent use in the recovery of hydrocarbons from the subterranean formation 12. One method would be to allow the production of fluid from the well to move the isolation fluid, as shown in FIG. 7. The isolation fluid may consist of chemicals that break or reduce the viscosity of the fluid over time to allow easy flowing. Another method of recovering the isolation fluid 28 is to wash or reverse the fluid out by circulating a fluid, gas or foam into the wellbore 10, as shown in FIG. 8A. Another alternate method of recovering the isolation fluid 28 is to hydrajet it out using the hydrajetting tool 14, as shown in FIG. 8B. The latter methods are particularly well suited where the isolation fluid 28 contains solids and the well is highly deviated or horizontal. The following is an another method of completing a well in a subterranean formation in accordance with the present invention. First, the wellbore 10 is drilled in the subterranean formation 12. Next, the first zone 16 in the subterranean formation 12 is perforated by injecting a pressurized fluid through the hydrajetting tool 14 into the subterranean formation (FIG. 9A), so as to form one or more perforation tunnels 20, as shown, for example, in FIG. 9B. During the performance of this step, the hydrajetting tool 14 is kept stationary. Alternatively, however, the hydrajetting tool 14 can be fully or partially rotated so as to cut slots into the formation. Alternatively, the hydrajetting tool 14 can be axially moved or a combination of rotated and axially moved within the wellbore 10 so as to form a straight or helical cut or slot. Next, one or more fractures 24 are initiated in the first zone 16 of the subterranean formation 12 by injecting a fracturing fluid into the one or more perforation tunnels through the hydrajetting tool 14, as shown, for example, in FIG. 3. Initiating the fracture with the hydrajetting tool 14 is advantageous over conventional initiating techniques because this technique allows for a lower breakdown pressure on the formation. Furthermore, it results in a more accurate and better quality perforation. Fracturing fluid can be pumped down the annulus 19 as soon as the one or more fractures 24 are initiated, so as to propagate the fractures 24, as shown in FIG. 9B, for example. Any cuttings left in the annulus from the perforating step are pumped into the fractures 24 during this step. After the fractures 24 have been initiated, the hydrajetting tool 14 is moved up hole. This step can be performed while the fracturing fluid is being pumped down through the annulus 19 to propagate the fractures 24, as shown in FIG. 9C. The rate of fluid being discharged through the hydrajetting tool 14 can be decreased once the fractures 24 have been initiated. The annulus injection rate may or may not be increased at this juncture in the process. After the fractures 24 have been propagated and the hydrajetting tool 14 has been moved up hole, the isolation fluid 28 in accordance with the present invention can be pumped into the wellbore 10 adjacent to the first zone 16. Over time the isolation fluid 28 plugs the one or more fractures 24 in the first zone 16, as shown, for example, in FIG. 9D. (Although not shown, those of skill in the art will appreciate that the isolation fluid 28 can permeate into the fractures 24.) The steps of perforating the formation, initiating the fractures, propagating the fractures and plugging or partially sealing the fractures are repeated for as many additional zones as desired, although only a second zone 30 is shown in FIGS. 6-10. After all of the desired fractures have been formed, the isolation fluid 28 can be removed from the subterranean formation 12. There are a number of ways of accomplishing this in addition to flowing the reservoir fluid into the wellbore and to those already mentioned, namely reverse circulation and hydrajetting the fluid out of the wellbore 10. In another method, acid is pumped into the wellbore 10 so as to activate, de-activate, or dissolve the isolation fluid 28 in situ. In yet another method, nitrogen is pumped into the wellbore 10 to flush out the wellbore and thereby remove it of the isolation fluid 28 and other fluids and materials that may be left in the wellbore. Yet another method in accordance with the present invention will now be described. First, as with the other methods, wellbore 10 is drilled. Next, first zone 16 in subterranean formation 12 is perforated by injecting a pressurized fluid through hydrajetting tool 14 into the subterranean formation, so as to form one or more perforation tunnels 20. The hydrajetting tool 14 can also be rotated or rotated and/or axially moved during this step to cut slots into the subterranean formation 12. Next, one or more fractures 24 are initiated in the first zone 16 of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels 20 through the hydrajetting tool 14. Following this step or simultaneous with it, additional fracturing fluid is pumped into the one or more fractures 24 in the first zone 16 through annulus 19 in the wellbore 10 so as to propagate the fractures 24. Any cuttings left in the annulus after the drilling and perforation steps may be pumped into the fracture during this step. Simultaneous with this latter step, the hydrajetting tool 14 is moved up hole. Pumping of the fracture fluid into the formation through annulus 19 is then ceased. All of these steps are then repeated for the second zone 30 and any subsequent zones thereafter. The rate of the fracturing fluid being ejected from the hydrajetting tool 14 is decreased as the tool is moved up hole and even may be halted altogether. An additional method in accordance with the present invention will now be described. First, as with the other methods, wellbore 10 is drilled. Next, first zone 16 in subterranean formation 12 is perforated by injecting a pressurized fluid through hydrajetting tool 14 into the subterranean formation, so as to form one or more perforation tunnels 20. The hydrajetting tool 14 can be rotated during this step to cut slots into the subterranean formation 12. Alternatively, the hydrajetting tool 14 can be rotated and/or moved axially within the wellbore 10, so as to create a straight or helical cut into the formation 16. Next, one or more fractures 24 are initiated in the first zone 16 of the subterranean formation by injecting a fracturing into the one or more perforation tunnels or cuts 20 through the hydrajetting tool 14. Following this step or simultaneous with it, additional fracturing fluid is pumped into the one or more fractures 24 in the first zone 16 through annulus 19 in the wellbore 10 so as to propagate the fractures 24. Any cuttings left in the annulus after the drilling and perforation steps are pumped into the fracture during this step. Simultaneous with this latter step, the hydrajetting tool 14 is moved up hole and operated to perforate the next zone. The fracturing fluid is then ceased to be pumped down the annulus 19 into the fractures, at which time the hydrajetting tool starts to initiate the fractures in the second zone. The process then repeats. Yet another method in accordance with the present invention will now be described with reference to FIGS. 10A-C. First, as with the other methods, wellbore 10 is drilled. Next, first zone 16 in subterranean formation 12 is perforated by injecting a pressurized fluid through hydrajetting tool 14 into the subterranean formation, so as to form one or more perforation tunnels 20, as shown in FIG. 10A. The fluid injected into the formation during this step typically contains an abrasive to improve penetration. The hydrajetting tool 14 can be rotated during this step to cut a slot or slots into the subterranean formation 12. Alternatively, the hydrajetting tool 14 can be rotated and/or moved axially within the wellbore 10, so as to create a straight or helical cut into the formation 16. Next, one or more fractures 24 are initiated in the first zone 16 of the subterranean formation by injecting a fracturing fluid into the one or more perforation tunnels or cuts 20 through the hydrajetting tool 14, as shown in FIG. 10B. During this step the base fluid injected into the subterranean formation may contain a very small size particle, such as a 100 mesh silica sand, which is also known as Oklahoma No. 1. Next, a second fracturing fluid that may or may not have a second viscosity greater than that of the first fracturing fluid, is injected into the fractures 24 to thereby propagate said fractures. The second fracturing fluid comprises the base fluid, sand, possibly a crosslinker, and one or both of an adhesive and consolidation agent. In one embodiment, the adhesive is SANDWEDGE conductivity enhancer manufactured by Halliburton and the consolidation agent is EXPEDITE consolidation agent also manufactured by Halliburton. The second fracturing fluid may be delivered in one or more of the ways described herein. Also, an acidizing step may also be performed. Next, the hydrajetting tool 14 is moved to the second zone 30, where it perforates that zone thereby forming perforation tunnels or cuts 32. Next, the fractures 34 in the second zone 30 are initiated using the above described technique or a similar technique. Next, the fractures 34 in the second zone are propagated by injecting a second fluid similar to above, i.e., the fluid containing the adhesive and/or consolidation agent into the fractures. Enough of the fracturing fluid is pumped downhole to fill the wellbore and the openings of fractures 24 in the first zone 16. This occurs as follows. The high temperature downhole causes the sand particles in the fracture fluid to bond to one another in clusters or as a loosely packed bed and thereby form an in situ plug. Initially, some of the fluid, which flows into the jetted tunnels and possibly part way into fractures 24 being concentrated as part of the liquid phase, leaks out into the formation in the first zone 16, but as those of ordinary skill in the art will appreciate, it is not long before the openings become plugged or partially sealed. Once the openings of the fractures 24 become filled, enough fracture fluid can be pumped down the wellbore 10 to fill some or all of the wellbore 10 adjacent fractures 24, as shown in FIG. 10C. Ultimately, enough fracture fluid and proppant can be pumped downhole to cause the first zone 16 to be plugged or partially sealed. This process is then repeated for subsequent zones after subsequent perforating and fracturing stages up-hole. FIGS. 11A-B illustrate the details of the hydrajetting tool 14 for use in carrying out the methods of the present invention. Hydrajetting tool 14 comprises a main body 40, which is cylindrical in shape and formed of a ferrous metal. The main body 40 has a top end 42 and a bottom end 44. The top end 42 connects to coil tubing 18 for operation within the wellbore 10. The main body 40 has a plurality of nozzles 46, which are adapted to direct the high pressure fluid out of the main body 40. The nozzles 46 can be disposed, and in one certain embodiment are disposed, at an angle to the main body 40, so as to eject the pressurized fluid out of the main body 40 at an angle other than 90°. The hydrajetting tool 14 further comprises means 48 for opening the hydrajetting tool 14 to fluid flow from the wellbore 10. Such fluid opening means 48 includes a fluid-permeable plate 50, which is mounted to the inside surface of the main body 40. The fluid-permeable plate 50 traps a ball 52, which sits in seat 54 when the pressurized fluid is being ejected from the nozzles 46, as shown in FIG. 11A. When the pressurized fluid is not being pumped down the coil tubing into the hydrajetting tool 14, the wellbore fluid is able to be circulated up to the surface via opening means 48. More specifically, the wellbore fluid lifts the ball 52 up against fluid-permeable plate 50, which in turn allows the wellbore fluid to flow up the hydrajetting tool 14 and ultimately up through the coil tubing 18 to the surface, as shown in FIG. 11B. As those of ordinary skill in the art will recognize other valves can be used in place of the ball and seat arrangement 52 and 54 shown in FIGS. 11A and 11B. Darts, poppets, and even flappers, such as a balcomp valves, can be used. Furthermore, although FIGS. 11A and 11B only show a valve at the bottom of the hydrajetting tool 14, such valves can be placed both at the top and the bottom, as desired. Yet another method in accordance with the present invention will now be described. First, the first zone 16 in the subterranean formation 12 is perforated by injecting a perforating fluid through the hydrajetting tool 14 into the subterranean formation, so as to form perforation tunnels 20, as shown, for example, in FIG. 1A. Next, fractures 24 are initiated in the perforation tunnels 20 by pumping a fracturing fluid through the hydrajetting tool 14, as shown, for example in FIG. 3. The fractures 24 are then propagated by injecting additional fracturing fluid into the fractures through both the hydrajetting tool 14 and annulus 19. The fractures 24 are then plugged, at least partially, by pumping an isolation fluid 28 into the openings of the fractures 24 and/or wellbore section adjacent to the fractures 24. The isolation fluid 28 can be pumped into this region either through the annulus 19, as shown in FIG. 4, or through the hydrajetting tool 14, as shown in FIG. 5, or a combination of both. Once the fractures 24 have been plugged, the hydrajetting tool 14 is moved away from the first zone 16. It can either be moved up hole for subsequent fracturing or downhole, e.g., when spotting a fluid across perforations for sealing where it is desired to pump the chemical from a point below the zone of interest to get full coverage—the tool is then pulled up through the spotted chemical. Lastly, these steps or a subset thereof, are repeated for subsequent zones of the subterranean formation 12. As is well known in the art, a positioning device, such as a gamma ray detector or casing collar locator (not shown), can be included in the bottom hole assembly to improve the positioning accuracy of the perforations. Therefore, the present invention is well-adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While the invention has been depicted, described, and is defined by reference to exemplary embodiments of the invention, such a reference does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. In particular, as those of skill in the art will appreciate, steps from the different methods disclosed herein can be combined in a different manner and order. The depicted and described embodiments of the invention are exemplary only, and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects. | <SOH> BACKGROUND OF THE INVENTION <EOH>In some wells, it is desirable to individually and selectively create multiple fractures having adequate conductivity, usually a significant distance apart along a wellbore, so that as much of the hydrocarbons in an oil and gas reservoir as possible can be drained/produced into the wellbore. When stimulating a reservoir from a wellbore, especially those that are highly deviated or horizontal, it is difficult to control the creation of multi-zone fractures along the wellbore without cementing a liner to the wellbore and mechanically isolating the zone being fractured from previously fractured zones or zones not yet fractured. Traditional methods to create fractures at predetermined points along a highly deviated or horizontal wellbore vary depending on the nature of the completion within the lateral (or highly deviated) section of the wellbore. Only a small percentage of the horizontal completions during the past 15 or more years used a cemented liner type completion; most used some type of non-cemented liner or a bare openhole section. Furthermore, many wells with cemented liners in the lateral were also completed with a significant length of openhole section beyond the cemented liner section. The best known way to achieve desired hydraulic fracturing isolation/results is to cement a solid liner in the lateral section of the wellbore, perform a conventional explosive perforating step, and then perform fracturing stages along the wellbore using some technique for mechanically isolating the individual fractures. The second most successful method involves cementing a liner and significantly limiting the number of perforations, often using tightly grouped sets of perforations, with the number of total perforations intended to create a flow restriction giving a back-pressure of about 100 psi or more, due to fluid flow restriction based on the wellbore injection rate during stimulation, with some cases approaching 1000 psi flow resistance. This technology is generally referred to as “limited entry” perforating technology. In one conventional method, after the first zone is perforated and fractured, a sand plug is installed in the wellbore at some point above the fracture, e.g., toward the heel. The sand plug restricts any meaningful flow to the first zone fracture and thereby limits the loss of fluid into the formation, while a second upper zone is perforated and fracture stimulated. One such sand plug method is described in SPE 50608. More specifically, SPE 50608 describes the use of coiled tubing to deploy explosive perforating guns to perforate the next treatment interval while maintaining well control and sand plug integrity. The coiled tubing and perforating guns were removed from the well and then the next fracturing stage was performed. Each fracturing stage was ended by developing a sand plug across the treatment perforations by increasing the sand concentration and simultaneously reducing pumping rates until a bridge was formed. The paper describes how increased sand plug integrity could be obtained by performing what is commonly known in the cementing services industry as a “hesitation squeeze” technique. A drawback of this technique, however, is that it requires multiple trips to carry out the various stimulation and isolation steps. More recently, Halliburton Energy Services, Inc. has introduced and proven the technology for using hydrajet perforating, jetting while fracturing, and co-injection down the annulus. In one method, this process is generally referred to by Halliburton as the SURGIFRAC process or stimulation method and is described in U.S. Pat. No. 5,765,642, which is incorporated herein by reference. The SURGIFRAC process has been applied mostly to horizontal or highly deviated wellbores, where casing the hole is difficult and expensive. By using this hydrajetting technique, it is possible to generate one or more independent, single plane hydraulic fractures; and therefore, highly deviated or horizontal wells can be often completed without having to case the wellbore. Furthermore, even when highly deviated or horizontal wells are cased, hydrajetting the perforations and fractures in such wells generally result in a more effective fracturing method than using traditional explosive charge perforation and fracturing techniques. Thus, prior to the SURGIFRAC technique, methods available were usually too costly to be an economic alternative, or generally ineffective in achieving stimulation results, or both. | <SOH> SUMMARY OF THE INVENTION <EOH>The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the exemplary embodiments, which follows. The present invention is directed to a method of completing a well using a hydrajetting tool and subsequently plugging or partially sealing the fractures in each zone with an isolation fluid. In accordance with the present invention, the hydrajetting tool can perform one or more steps, including but not limited to, the perforating step, the perforating and fracture steps, and the perforating, fracture and isolation steps. More specifically, the present invention is directed to a method of completing a well in a subterranean formation, comprising the following steps. First, a wellbore is drilled in the subterranean formation. Next, depending upon the nature of the formation, the wellbore is lined with a casing string or slotted liner. Next, a first zone in the subterranean formation is perforated by injecting a pressurized fluid through a hydrajetting tool into the subterranean formation, so as to form one or more perforation tunnels. This fluid may or may not contain solid abrasives. Following the perforation step, the formation is fractured in the first zone by injecting a fracturing fluid into the one or more perforation tunnels, so as to create at least one fracture along each of the one or more perforation tunnels. Next, the one or more fractures in the first zone are plugged or partially sealed by installing an isolation fluid into the wellbore adjacent to the fractures and/or inside the openings of the fractures. In at least one embodiment, the isolation fluid has a greater viscosity than the fracturing fluid. Next, a second zone of the subterranean formation is perforated and fractured. If it is desired to fracture additional zones of the subterranean formation, then the fractures in the second zone are plugged or partially sealed by the same method, namely, installing an isolation fluid into the wellbore adjacent to the fractures and/or inside the openings of the fractures. The perforating, fracturing and sealing steps are then repeated for the additional zones. The isolation fluid can be removed from fractures in the subterranean formation by circulating the fluid out of the fractures, or in the case of higher viscosity fluids, breaking or reducing the fluid chemically or hydrajetting it out of the wellbore. Other exemplary methods in accordance with the present invention are described below. An advantage of the present invention is that the tubing string can be inside the wellbore during the entire treatment. This reduces the cycle time of the operation. Under certain conditions the tubing string with the hydrajetting tool or the wellbore annulus, whichever is not being used for the fracturing operation, can also be used as a real-time BHP (Bottom Hole Pressure) acquisition tool by functioning as a dead fluid column during the fracturing treatment. Another advantage of the invention is the tubing string provides a means of cleaning the wellbore out at anytime during the treatment, including before, during, after, and in between stages. Tubulars can consist of continuous coiled tubing, jointed tubing, or combinations of coiled and jointed tubing. | 20040324 | 20070605 | 20050929 | 70726.0 | 1 | SMITH, MATTHEW J | METHODS OF ISOLATING HYDRAJET STIMULATED ZONES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,808,255 | ACCEPTED | Method and apparatus for optimized CO post-combustion in low NOx combustion processes | An improved process for burning a fuel to produce a flue gas is disclosed. The fuel is burned in a main combustion zone in the presence of a main combustion oxidant to produce combustion products. The combustion products are mixed in a post-combustion zone positioned downstream from the main combustion zone. The post-combustion zone is provided with a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone. An post-combustion oxidant is injected into the combustion products in the injection zone. At least one of (a) the residence time of the combustion products in the post-combustion zone, (b) the temperature range of the combustion products contained within the injection zone and (c) the oxygen content of the oxidant is controlled to optimize the level of CO and NOx in the flue gas. | 1. A process for burning a fuel to produce a flue gas, the process comprising: burning the fuel in a main combustion zone in the presence of a main combustion oxidant to produce combustion products; mixing the combustion products in a post-combustion zone positioned downstream from the main combustion zone, the post-combustion zone having a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone; injecting a post-combustion oxidant into the combustion products in the injection zone; and controlling at least one of (a) the residence time of the combustion products in the post-combustion zone, (b) the temperature range of the combustion products contained within the injection zone and (c) the oxygen content of the oxidant, to optimize the level of CO and NOx in the flue gas. 2. A process for burning a fuel to produce a flue gas, the process comprising: burning the fuel in a main combustion zone in the presence of a main combustion oxidant to produce combustion products; mixing the combustion products in a post-combustion zone positioned downstream from the main combustion zone, the post-combustion zone having a recirculation zone positioned proximate to the main combustion zone and an injection zone contained within the recirculation zone; injecting a post-combustion oxidant into the combustion products in the injection zone; and controlling at least one of (a) the residence time of the combustion products in the post-combustion zone, (b) the temperature range of the combustion products contained within the injection zone and (c) the oxygen content of the oxidant, to optimize the level of CO and NOx in the flue gas. 3. The process of claim 1 wherein the temperature of the combustion products contained within the post-combustion zone is maintained between about 800° C. and about 1300° C. 4. The process of claim 3 wherein the temperature of the combustion products contained within the post-combustion zone is maintained between about 800° C. and about 1100° C. 5. The process of claim 1 wherein the post-combustion zone is provided with at least one baffle. 6. The process of claim 5 wherein the post-combustion zone is provided with a plurality of baffles. 7. The process of claim 6 wherein the baffles are oriented substantially perpendicular to the general direction of flow of the combustion products. 8. The process of claim 6 wherein the baffles are disposed in staggered relation to one another. 9. The process of claim 8 wherein the baffles are oriented substantially perpendicular to the general direction of flow of the combustion products. 10. The process of claim 1 wherein the post-combustion zone is provided with a diffuser. 11. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products in axial, countercurrent relation to the direction of flow of the combustion products. 12. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products in radial, perpendicular relation to the direction of flow of the combustion products. 13. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products in radial and tangential relation to the direction of flow of the combustion products to produce a swirl pattern within the flow of the combustion products. 14. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products in oblique, countercurrent relation to the direction of flow of the combustion products. 15. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products at an average velocity of between about 5 meters per second and about 120 meters per second. 16. The process of claim 1 wherein the post-combustion oxidant is injected into the combustion products with at least one lance. 17. The process of claim 1 wherein the post-combustion oxidant is injected in the combustion products in a staged relation to the direction of flow of the combustion products. 18. The process of claim 1, wherein the stoichiometric amount of oxygen contained in the main oxidant is between about 0.7 and 1.0 of the amount necessary for complete combustion. 19. The process of claim 1 wherein the total oxygen composition of the post-combustion oxidant entering the oxidant chamber exceeds 21%. 20. The process of claim 19 wherein the total oxygen composition of the post-combustion oxidant entering the oxidant chamber is between 21% and 35%. 21. The process of claim 1 wherein a heat-absorbing material is injected into the main combustion zone during the burning to reduce the temperature of the combustion products within the combustion zone. 22. The process of claim 1 wherein the burning is conducted by oscillating combustion process techniques. 23. The process of claim 18 wherein the burning is conducted by oscillating combustion process techniques. 24. The process of claim 20 wherein the burning is conducted by oscillating combustion process techniques. 25. A process for burning a fuel to produce a flue gas, the process comprising: burning the fuel in a main combustion zone in the presence of a main combustion oxidant to produce combustion products; mixing the combustion products in a post-combustion zone positioned downstream from the main combustion zone, the post-combustion zone having a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone; the post-combustion zone being provided with at least one of a diffuser or a plurality of baffles oriented substantially perpendicular to the general direction of flow of the combustion products and being disposed in staggered relation to one another; maintaining the temperature of the combustion products contained within the post-combustion zone between about 800° C. and about 1100° C.; injecting with at least one lance a post-combustion oxidant into the combustion products in the injection zone at an average velocity of between about 5 meters per second and about 120 meters per second; maintaining the stoichiometric amount of oxygen contained in the main oxidant to be between about 0.7 and 1.0 of the amount necessary for complete combustion; maintaining the total oxygen composition of the post-combustion oxidant entering the oxidant chamber to be between 21% and 35%; injecting a heat-absorbing material into the main combustion zone during the burning to reduce the combustion temperature within the combustion zone; conducting the burning by oscillating combustion process techniques; and controlling at least one of (a) the residence time of the combustion products in the post-combustion zone, (b) the temperature of the combustion products contained within the injection zone and (c) the oxygen content of the oxidant, to optimize the level of CO and NOx in the flue gas. 26. The process of claim 25 wherein the post-combustion oxidant is injected into the combustion products in axial, countercurrent relation to the direction of flow of the combustion products. 27. The process of claim 25 wherein the post-combustion oxidant is injected into the combustion products in radial, perpendicular relation to the direction of flow of the combustion products. 28. The process of claim 25 wherein the post-combustion oxidant is injected into the combustion products in radial, offset relation to the direction of flow of the combustion products to produce a swirl pattern within the flow of the combustion products. 29. The process of claim 25 wherein the post-combustion oxidant is injected into the combustion products in oblique, countercurrent relation to the direction of flow of the combustion products. 30. A process for burning a fuel to produce a flue gas, the process comprising: burning the fuel in a main combustion zone in the presence of a main combustion oxidant to produce combustion products; mixing the combustion products in a post-combustion zone positioned downstream from the main combustion zone, the post-combustion zone having a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone; injecting a post-combustion oxidant into the combustion products in an injection zone positioned downstream from the main combustion zone; and combusting the combustion products with the post-combustion oxidant, thereby optimizing the levels of CO and NOx in the flue gas. 31. A process of retrofitting a boiler comprising a combustion apparatus having a main combustion zone configured for burning fuel in the presence of a main combustion oxidant to produce combustion products, the process comprising: providing a mixing device downstream of the main combustion zone positioned and configured to increase a residence time of the combustion products in a recirculation zone proximate to the main combustion zone in comparison to an absence of the mixing device; providing an injection device positioned and configured to inject a post-combustion oxidant into the combustion products in the injection zone, thereby facilitating combustion of the combustion products and the post-combustion oxidant such that levels of CO and NOx resulting therefrom are optimized. | CROSS REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application No. 60/491,220, filed Jul. 30, 2003. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for optimized post-combustion of CO and unburned hydrocarbons in combustion processes where low levels of NOx emissions are to be achieved. 2. Related Art High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce significant quantities of nitrogen oxides (NOx) per unit of material processed. At the same time, regulations on emissions from industrial furnaces are becoming increasingly more stringent, especially in areas such as California. Consequently, there has been a demand for improved combustion technologies allowing reduction of NOx formation. Different solutions have been developed, usually based on the principle of either staged or diluted combustion. However, the operating conditions that favor the reduction of NOx emissions typically affect the combustion process itself such that combustion can become incomplete, thereby generating carbon monoxide (CO) and unburned hydrocarbons (HC). For this reason, and in order to achieve optimum emission performances, some of the low NOx technologies have had to be coupled with some sort of post-combustion system in order to remove CO and unburned HC from the flue gas before being exhausted into the atmosphere. The present invention relates to industrial combustion processes, including high-temperature furnaces, industrial boilers, and utility boilers, facing stringent NOx regulations. Because nitrogen oxides (primarily NO and NO2, hereafter NOx) have been identified as a major cause of air pollution as well as a significant health hazard in ambient air, they have been defined as a criteria pollutant by the Clean Air Act Amendment (CAAA), which has established environmental limits in determined locations. To comply with these regulations, many U.S. combustion process operators have had to implement NOx control technologies in the past few years. This trend will most likely propagate in other areas and become even more pronounced. Widely implemented low NOx technologies included combustion techniques, allowing to significantly prevent the formation of NOx inside the combustion chamber, in contrast to post-treatment techniques (such as Selective Catalytic Reduction), where NOx is removed from flue gases through chemical reactions. Among these combustion-based NOx control technologies, many different techniques have been proposed and optimized, based on the following concepts: 1) reduction of the temperature in the combustion zone to limit NOx formation mechanism, 2) decrease of the oxygen concentration available for NOx formation in the high temperature zones, and/or 3) creation of conditions under which NOx can be reduced to molecular nitrogen by reacting with hydrocarbon fragments. One example of this general type of technology is low excess air, or reducing the available oxygen to the point which is just sufficient to oxidize the fuel but not so much as to cause emissions such as NOx, and CO (i.e. stoichiometric balance). Another example is staged combustion, or staging combustion by arranging the inlets of fuel or air to achieve off-stoichiometric firing conditions in the different zones of combustion. Still another example is flue gas recirculation (FGR), or recirculating the flue gas to the combustion zone as a diluent to reduce flame temperature and oxygen concentration. Another example is oscillating combustion, or oscillating the flow of fuel in order to create fuel-rich and fuel-lean combustion zones, and operating only under off-stoichiometric conditions. A final example is gas reburning, or introducing fuel gas to bum in the post combustion zone, generating hydrocarbon fragments which reduce the NOx formed in the main combustion zone to molecular nitrogen. Advantageous as the foregoing examples can be, they each suffer some drawbacks. When applied to minimize NOx production, these examples can affect the mixing of the reactants, generating instability in the combustion process, and eventually causing incomplete combustion. The result is the unwanted exhaust of CO and unburned hydrocarbons from the combustion system. This can be explained by the fact that CO and unburned hydrocarbon formation is dependent on the same three basic factors that influence NOx emissions: temperature, oxygen concentration and residence time at elevated temperatures. Unfortunately, each of these must be controlled in the opposite direction from that of NOx reduction: if all three factors are decreased, NOx production can be dramatically reduced but CO production is enhanced, and vice versa. As CO emissions can rarely be sacrificed for reduced NOx because low emission systems must keep both pollutants at a minimum, it is then necessary to implement a CO removal system downstream of the combustion region. Again two different approaches are basically available in the prior art: a first one, based on catalytic oxidation of CO in the flue gas exhaust section, at reduced temperature, and a second one, based on post-combustion of CO with an oxidant, inside or in the vicinity of the combustion chamber. A well known catalytic method is the Non-Selective Catalytic Reduction (NSCR), used in rich burn engines for simultaneous reduction of NOx, CO and volatile organic compounds. With this method, the engine is tuned to run richer so that there is a concurrent decrease in NOx and increase in reducing agents (CO and HC). Then downstream of the engine, in the presence of a catalyst and at reduced temperature, NOx react with CO, HCs or H2 to produce nitrogen, carbon dioxide and water. If this method allows a combined reduction of the different pollutants, it can however be quite expensive, with the need for a tight process control system and a costly catalytic reactor that has to be replaced periodically. A similar system for gas-fired heating units is also presented in German Patent DE 4006735, issued to Ragert. Thus, a problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide a post-combustion system including at least one, and preferably a combination, of a flue gas recirculation zone, a flue gas mixing zone and an oxidant injection zone. Still another problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide a method that sufficiently increases the residence time of combustion products inside the combustion chamber, especially in regions where temperature is low enough to prevent the formation of NOx. Another problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide enhancement of the mixing of combustion products inside the combustion chamber in order to favor the completion of the combustion. An even further problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide optimized post-combustion oxidant injection devices that distribute as evenly as possible this oxidant into the post-combustion zone. For the foregoing reasons, there has been defined a long felt and unsolved need for a method for efficiently and cost-effectively removing CO and unburned HC from the flue gas of low NOx combustion processes without re-creating substantial NOx emissions. SUMMARY OF THE INVENTION A method for optimized post-combustion of CO and unburned hydrocarbons in combustion processes where low levels of NOx emissions are to be achieved is disclosed. The method is adaptable for use in many combustion processes, including industrial boilers, utility boilers and industrial furnaces. Through the proposed technique of post-combustion, CO emissions can be kept below regulated levels without regenerating additional NOx emissions. This post-combustion method is based on a combination of a recirculation zone of the combustion products, a flue gas mixing zone and finally, an oxidant injection zone, all designed to optimize the residence time, temperature range and mixing of the various reactants. In one preferred embodiment, this method and apparatus are associated with the technology of oscillating combustion, thus providing at the same time very low NOx emissions and CO emissions, in compliance with current regulations. A previous application of the assignee, U.S. patent application Ser. No. 10/310,197, filed Dec. 3, 2002, describes a process using the technology of oscillating combustion to reduce NOx emissions, which usually involve the simultaneous implementation of a post-combustion device so as to keep CO emissions below compliance levels. Tests have shown that the fine-tuning of such post-combustion techniques is very complicated and much of the NOx reduction achieved at flame level can be spoiled in this area if CO is not burned out in an appropriate manner. It is an object of the present invention to provide a post-combustion system including at least one, and preferably a combination, of a flue gas recirculation zone, a flue gas mixing zone and an oxidant injection zone. Yet another object of the present invention to provide a method that sufficiently increases the residence time of combustion products inside the combustion chamber, especially in regions where temperature is low enough to prevent the formation of NOx. Still another object of the present invention to provide enhanced mixing of combustion products inside the combustion chamber in order to favor the completion of the combustion. An even further object of the present invention to provide optimized post-combustion oxidant injection devices that distribute as evenly as possible this oxidant into the post-combustion zone. These and other objects, advantages and features of the present invention will be apparent from the detailed description that follows. BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description that follows, reference will be made to the following figures: FIG. 1 is a schematic illustration of a preferred embodiment of a post-combustion process; FIG. 2 is a schematic illustration of a preferred embodiment of a post-combustion process utilizing peripheral baffles; FIG. 3 is a schematic illustration of a preferred embodiment of a post-combustion process utilizing staggered baffles; FIG. 4 is a schematic illustration of a preferred embodiment of a post-combustion process utilizing a diffuser design; FIG. 5 is a schematic illustration of a preferred embodiment of a post-combustion process utilizing injection nozzles; FIG. 6 is a schematic illustration of a preferred embodiment of a post-combustion process utilizing injection nozzles introducing swirl patterns; FIG. 7 is a schematic illustration of a preferred embodiment utilizing staged, post-combustion injection; FIG. 8 is a schematic illustration of a preferred embodiment of hybrid combustion/post-treatment NOx reduction; and FIG. 9 is a schematic illustration of a preferred embodiment of an oscillating combustion method. DESCRIPTION OF PREFERRED EMBODIMENTS In a preferred embodiment, a method providing for optimal removal of CO in low NOx combustion process is disclosed. This method accomplishes two antagonist functions: burning out CO and unburned HC without generating additional NOx emissions. To achieve this result, three parameters are controlled. First, the residence time of the reactants in the post-combustion zone; second, the temperature at which the post-combustion is performed; and third, the completeness of mixing between the reactants. Again referring to the preferred embodiment, a two-step method is disclosed. Since low NOx combustion techniques typically are run above stoichiometric conditions—i.e., with excess air—there is always some oxygen available in the combustion products, even if some CO and unburned HC are present. Therefore, the first step for reducing CO and unburned HC is to force the reaction between them and the still available oxygen before the exit of the combustion chamber. Then, if anything remains unburned, additional oxidant is injected to complete combustion. The post-combustion region is therefore partitioned into different zones, as shown in FIG. 1. The combustion products produced by the main combustion zone travel successively through a recirculation zone, a mixing zone and an injection zone. Note that, as illustrated, the mixing zone can overlap the recirculation zone and injection zone. In the recirculation zone, the flue gases are recirculated, providing additional residence time as well as increasing the overall turbulence. Downstream of this zone, combustion products are then sent through a mixing zone where additional turbulence is generated, just before entering the final injection zone, where remaining CO and unburned HC meet with the post-combustion oxidant. Typically, in the first two zones, a portion of the CO and unburned HC can mix with available excess oxygen from the main combustion region and be removed, even without the need of additional oxidant. At the same time, due to the increased residence time and turbulence, these first two zones allow for a homogenization of the overall combustion products flow, thus leading to a reduction of its peak temperature. This control of the temperature range in the post-combustion zone facilitates removal of CO without undue generation of NOx. In a preferred embodiment, the post-combustion is performed in the temperature window between about 800° C. and 1300° C., and more preferably between 800° C. and 1100° C. By using these two zones and positioning the overall post-combustion zone in the combustion chamber, CO is burned out in this temperature range and re-creation of NOx is substantially avoided. In a preferred embodiment, this post-combustion zone is positioned at the very end of the combustion chamber, in the vicinity of the outlet, since this location provides flue gas temperatures that are lowest and also provides the location where the entire flue gas flow is converging. However, depending on temperature levels encountered in various processes, the post-combustion system can be located elsewhere, e.g., either further inside the combustion chamber, or downstream, in the early section of the exhaust duct. Having thus provided temperature range control in the first two zones, the combination of the mixing zone and the injection zone facilitates effective mixing of the post-combustion oxidant with the combustion products, thus allowing a fast CO burnout before the combustion chamber outlet and preventing NOx formation. Although in the preferred embodiment, these three different zones are placed in the described order, it is understood that other combinations of at least one of these zones can be effective. Referring now to FIG. 2, a method for recirculating combustion products in the combustion chamber is shown. Baffles are installed on the chamber walls and oriented perpendicularly to the flow, to concentrate the flow in the center part of the chamber and to promote recirculation immediately downstream of the baffle, with the associated increase in residence time and turbulence. As shown in FIG. 3, staggered baffles are positioned successively at the bottom and at the top of the chamber, and are oriented perpendicularly to the flow. In both FIGS. 2 and 3, the number of baffles, their axial location and their size should be optimized case by case according to flow specifications, combustion chamber geometry, NOx and CO level. It should also be noted that various methods could be employed to implement these baffles in the combustion chamber: either fastened directly on the combustor walls, or fastened on an external body inserted through the combustor walls. These designs permit recirculation and also substantial mixing of the flue gas, thereby (a) promoting the reaction between CO and available excess oxygen, (b) reducing the peak temperatures encountered within the post-combustion chamber and (c) creating turbulent conditions for the subsequent mixing with post-combustion oxidant. FIG. 4 shows the side view of a preferred embodiment constructed and arranged to enhance mixing and turbulence of the combustion products before the injection of post-combustion oxidant. This embodiment illustrates a diffuser, through which combustion products are forced to travel, thus generating a swirl pattern due to the orientation of the fins. This type of mechanical mixer can typically be mounted on the lances used for post-combustion injection. The number and orientation of the fins, as well as the relative position of such diffuser in relation to the recirculation and injection zones, are also to be adjusted case by case, according to process characteristics. It should be noted that different designs are possible to increase the mixing of combustion products, the bottom line being to disturb the flow and force it to change directions throughout its travel toward the exhaust of the combustion chamber. Note that, in post-combustion oxidant injection, optimum mixing of the oxidant with the products of combustion so as to reach CO and unburned HC molecules as quickly as possible is preferred. Because the reaction time needed for the combustion of CO is on the order of a few milliseconds, the effectiveness of the CO removal is chiefly a matter of mixing. The better the mixing between the reactants, the closer to the end of the chamber can be located the injection system, thus allowing the post-combustion to happen in a region where the temperature is usually the lowest. Post-combustion oxidant can be injected through one or more lances located in the region close to the combustion chamber exhaust and inserted through the combustor walls. The number of lances and the exact location of these injectors are also to be optimized according to specificities of the given applications, especially the size and geometry of the combustion chamber. To optimize the mixing of the injected oxidant with CO and unburned HC, several injection nozzles can be provided, as shown by FIG. 5. As seen in these drawings, in order to optimally combine with associated recirculation and mixing sub-systems, various injection directions are proposed: axially, facing the flow of combustion products; obliquely, with an angle between 0 and 90° compared to the flow or perpendicularly to the flow. The velocity is to be adjusted case by case, according to the type of nozzle and to the average velocity of the flue gas, preferably between 5 m/s and 120 m/s. Referring now to FIG. 6, injection is shown with a nozzle, the geometries of which are more fully shown in U.S. Pat. No. 5,356,213, the teachings of which are hereby incorporated by reference as if fully set forth herein. Injection of post-combustion oxidant is made perpendicularly to the flue gas flow with a unique swirl pattern, allowing the oxidant to reach and mix optimally with CO and unburned HC for effective burn out. This design can be employed with the diffuser system, for example downstream of it, and on the same injection lance, in such a manner that swirl patterns created by both systems (for the flue gas and for the oxidant) are rotating in opposite directions. With such a combination, high-quality mixing is then guaranteed between those reactants. Another method for improving the mixing between combustion products and the post-combustion oxidant is shown in FIG. 7, and illustrates a staged and progressive injection of the oxidant along the injection lance. This way, the oxidant can be spread over a larger volume of flue gas and the heat released by the combustion of CO can be evenly distributed over a larger volume. Specific materials can be selected for the implementation of recirculation, mixing and injection apparatus, to withstand the temperature ranges expected. Even when operated at relatively lower temperatures, e.g. between about 800° C. and 1100° C., material selection is important to withstand the thermal stresses. A preferred metal is Inconel, whose melting temperature is approximately around 1400° C. Ceramics can also be considered for such applications, as well as other materials selected to provide the appropriate high-temperature operability. Finally, water-cooled and air-cooled designs can be employed. Various post-combustion oxidants can be selected according to the amount of CO to be removed and to the characteristics of the combustor. For example, one suitable oxidant is atmospheric air, which can preferably be blown through injection lances. For higher CO removal efficiency, oxygen enrichment of the post-combustion air can be performed. The additional oxygen injected maintains a chemically active atmosphere around the combustion products, and particularly around CO and unburned HC, which accelerates their combustion. This way, an even faster burn out of CO and unburned HC can be achieved. However, associated drawbacks include higher local heat release, due to the reduction of the ballast usually created by the nitrogen present in the air, and expense. The oxygen content in the post-combustion oxidant is maintained between 21% and 100%, but is preferably maintained between 21% and 35%, to avoid too high local heat releases. To optimize the post-combustion of CO without re-creation of NOx, through the implementation of means to lower and control the temperature in the post-combustion region, additional inert fluids can be injected into the post-combustion space along with the oxidant so as to create heat sinks that can absorb the heat released during the combustion of CO and unburned HC. These inert fluids include nitrogen, recirculated flue gas from the exhaust duct, carbon dioxide, water or steam. It is preferred to use fluids with high heat capacities, so water and steam are preferred heat sinks. Water is even more preferred since on top of its high heat capacity, its heat of vaporization when transformed into steam inside the combustion chamber constitutes and additional heat sink. Injection of inert fluids as heat sinks is particularly indicated when oxygen-enriched air or pure oxygen is used as post-combustion oxidant. Thus, a post-combustion system which can be used as a combustion-staging device is provided. If the post-combustion system is optimized so that CO and unburned HC can be burnt out without production of additional NOx, it is possible to reduce the stoichiometric ratio at the burner level (i.e., in the main combustion zone) to create fuel-rich conditions and thus to further prevent production of NOx. The completion of the combustion is then achieved in the post-combustion zone through increased injection of oxidant. Preferably, the stoichiometric ratio at burner level is reduced below I and even more preferably between 0.7 and 1. Another preferred embodiment provides the post-combustion method as disclosed herein in combination with low NOx technology of oscillating combustion. An example of oscillating combustion is shown in in Applicant's co-pending U.S. patent application Ser. No. 10/310,197, filed 03 Dec. 2002, entitled “Process and Apparatus of Combustion for Reduction of Nitrogen Oxide Emissions.” In an actual working example, performances were monitored, producing the following results. The technology of oscillating combustion (OCT) was implemented in a 100 HP natural gas-fired industrial boiler in order to reduce NOx emissions below levels required by some U.S. local authorities. From a baseline of 60 ppm of NOx, the combustion technology (prior to utilizing the preferred embodiment) allowed to reduce NOx by more than 50%, but with concurrent formation of high amounts of CO and unburned HC. To burn out this CO and to keep its level below 400 ppm, post-combustion techniques were first implemented close to the outlet of the combustion chamber, based on the insertion of a lance through the boiler walls and the injection of post-combustion air. CO was then reduced significantly but not enough so as to be kept below compliance levels, and at the same time, some substantial amounts of NOx were re-created in this region, eventually leading to minor NOx reduction levels compared to the baseline without low NOx technology. An optimized post-combustion system was then implemented, according to the teachings of this disclosure. A peripheral ring was installed inside the combustion chamber, close to the exhaust of this chamber (FIG. 2). A post-combustion lance was inserted downstream of this ring, fitted with a diffuser (FIG. 4) and a swirl-inducing nozzle (FIG. 6) located a few inches downstream of the diffuser. Finally, the post-combustion oxidant used was oxygen-enriched air, with an O2 content of 30%. CO was effectively burned out and reduced below compliance levels, while NOx production levels were close to what was achieved without post-combustion. The results of these different trials are compiled in Table 1, here below: OCT + OCT + Standard Post- Optimized Post- OCT combustion combustion NOx reduction vs. 57% 22% 54% baseline (60 ppm @ 3% O2) CO 13000 1700 280 (ppm @ 3% O2) An improved process for burning a fuel to produce a flue gas is disclosed. The fuel is burned in a main combustion zone in the presence of a main combustion oxidant to produce combustion products. The combustion products are mixed and the combustion reaction is substantially completed in a post-combustion zone positioned downstream from the main combustion zone. The post-combustion zone has a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone. The post-combustion zone is provided preferably with at least one of a diffuser and a plurality of baffles oriented substantially perpendicular to the general direction of flow of the combustion products, disposed in staggered relation to one another. It is understood that these are provided to increase the residence time of gases within the respective chambers or zones. The temperature of the combustion products contained within the post-combustion zone is maintained between about 800° C. and about 1100° C. A post-combustion oxidant is injected via one or several lances into the combustion products in the injection zone at an average velocity of between about 5 meters per second and about 120 meters per second. The stoichiometric amount of oxygen contained in the main oxidant is maintained between about 0.7 and 1.0 of the amount necessary for complete combustion. The total oxygen content of the post-combustion oxidant entering the oxidant chamber is maintained between 21% and 50%, and more preferably between 21% and 35%. A heat-absorbing material can be injected into the post-combustion zone to further reduce the combustion temperature within this zone. The burning is conducted by oscillating combustion process techniques. At least one of (a) the residence time of the combustion products in the post-combustion zone, (b) the temperature of the combustion products contained within the injection zone and (c) the oxygen content of the oxidant is controlled to optimize the level of CO and NOx in the flue gas. The post-combustion oxidant can preferably be injected into the combustion products in one of four specified ways: in axial, countercurrent relation to the direction of flow of the combustion products; in radial, perpendicular relation to the direction of flow of the combustion products; in radial and tangential relation to the direction of flow of the combustion products to produce a swirl pattern within the flow of the combustion products; or in oblique, countercurrent relation to the direction of flow of the combustion products. In another preferred embodiment, the above described method can be combined with a method by which fuel is burned with an oxidant in a manner creating a higher NO2/NOx ratio than in usual combustion processes. Subsequently, the flue gases from the combustor are post-treated in a wet scrubber where an effective removal of NO2 can be achieved due to its high solubility in aqueous solutions. The remaining molecules of NOx produced in very little proportions in the combustor, are exhausted, allowing an overall very low level of NOx emissions in the atmosphere. This hybrid low NOx technology, based on a combination of combustion and post-combustion NOx reduction systems, provides a cost-effective alternative for systems requiring ultra-low levels of NOx emissions. Whereas in usual combustion systems NO2 accounts for between 5 and 10 percent of total NOx emissions (with NO accounting for the reminder), this method provides a combustion system design allowing not only an overall reduction of NOx emissions but also a reversion of the NO/NO2 ratio, through the conversion of most of the NO into NO2, inside of the combustion chamber. This way, the global amount of NOx generated is already reduced at the combustion level, and the remaining NOx is in a preferred form, easily captured downstream of the process. Indeed, NO2 gas has fairly high solubility and reactivity to water and in aqueous solutions or alkalis as compared with NO, and can be removed fairly easily by wet scrubbing. Thus, the method includes combustion control to create conditions where the hot combustion gases generated at the burner level can be cooled rapidly by turbulent mixing with cold air. In these conditions, most of the NO generated in the flame can be converted to NO2 (up to about 100%) and maintained in this form until the exit of the combustion process. This turbulent mixing is practically achieved through a particular method of oxidant staging: a first portion of the oxidant required to burn a given amount of fuel is actually injected along with this fuel at the burner level, whereas the balance of oxidant required for complete combustion is injected in a manner allowing mixing with hot combustion products downstream of the flame front region. By mixing this secondary oxidant with hot combustion gases in a region where temperature is already reduced, a significant part of the NO gets converted into NO2. One method of performing oxidant staging is disclosed in already issued patents: U.S. Pat. Nos. 5,302,111, 5,522,721 and 4,846,665. Oscillating combustion involves the forced, out-of-phase oscillation of the fuel and/or oxidant flow rate(s) provided to a burner to create successive fuel-rich and fuel-lean zones within the flame. These oscillations actually increase heat transfer by enhancing flame luminosity and turbulence, and retard NOx formation by avoiding stoichiometric combustion. If the combustion chamber is designed in a preferred manner, these oscillations can create all the conditions required for almost complete conversion of the already low level of NO into NO2: at the end of the combustion chamber, the hot gases from the fuel-rich zone eventually mix turbulently with the gases from the previous fuel-lean zone, containing mainly substantially cold air if conditions are lean enough. The phenomenon is even enhanced in the case of oscillating combustion since the fuel-rich periods are generating an additional supply of radicals and unburnt species (CO, H2 and hydrocarbons), which is particularly favorable for higher NO2 formation. At the exit of such a combustion chamber, NOx are already reduced by at least 30% compared to a conventional combustion system, and even preferably by at least 50%. With a preferred tuning of the oscillating combustion parameters, these NOx are also composed mainly of NO2 (i.e., NO2/NOx ratio above 50%), the NO2/NOx ratio being preferably higher than 80%, and even more preferably about 100%. This NO/NO2 repartition provides a dramatic advantage for post-treatment over conventional combustion systems where the majority of the NOx generated is in the form of NO. In these cases, as already explained previously, very costly catalysts and reagents (Ammonia, ozone, precious metals..) have to be used in order to either reduce NO to N2 or oxidize NO to NO2, which can then be readily captured. In the context of the invention, most of the NOx are exhausted in the form of NO2, which limits the post-treatment to a unique and less expensive scrubbing step. The advantage of this unique invention is actually to combine two cost-effective NOx reductions systems, which taken alone could not achieve very low NOx levels, but when combined, are able to compete with the most-effective ultra-low NOx technologies, at a reduced cost. As shown in FIG. 8, fuel is injected in a combustion chamber of a process, through one or more burners, along with an oxidant in order to generate hot combustion gases and heat to be transferred to the load. Thus, an additional supply of substantially cold O2-containing gas downstream of the flame front region is provided. By creating a turbulent mixing of this additional cold gas with the hot combustion gases resulting from the combustion region, a significant portion of the NO created in the flame can be converted into NO2. This phenomenon can be explained by taking a look at the physical mechanisms by which NO2 is produced. Using a combustion chemical kinetics mechanism with 29 gas phase reactions, it is found that NO2 is formed and destroyed by the following reactions: Reaction of Formation NO+HO2═NO2+OH (1) Reactions of Destruction NO2+H═NO+OH (2) NO2+O═NO+O2 (3) According to this mechanism, it appears that the quenching of the combustion gases by the cold O2-containing gas has two effects. First, the NO2 formation reaction may occur more readily, because quenching may result in a more abundant supply of the HO2 radicals, since reactions, other than (1) above, which use up HO2 do not proceed below a threshold temperature. Second, quenching the hot combustion gases “freezes” the NO2, viz., the destruction reactions (2) and (3) above, do not proceed because the temperature is below a critical threshold value. The supply of substantially cold O2-containing gas can be provided in different ways. The most preferred method varies according to the combustion chamber design, the number of burners, the type of load and the temperature repartition in the chamber. It should be noted that FIG. 8 only illustrates the location of the mixing between the substantially cold gas and the hot combustion gases (downstream of the flame front); however, unlike what is shown in FIG. 8, the cold gas is not necessarily injected separately from the main oxidant. Some special injection patterns of the oxidant may allow the delayed mixing of part of this oxidant with the combustion gases. These particular injection patterns are described below. A first method considered is the use of burners with high level of oxidant staging. If the mixing of the staged oxidant with the products of combustion takes place far enough from the burner, in a region where the temperature is already reduced compared to the flame temperature, a good NO to NO2 conversion is expected. A second method to achieve this natural conversion of NO to NO2 is by performing over-fire air, or injection of an oxidant downstream of the flame region, from a port different than the burner one. A third and preferred method is by implementing the technology of oscillating combustion, as referred to above and as more fully described in the references noted above and incorporated herein by reference. An objective of oscillating combustion is to create successive, NOx retarding, fuel-rich and fuel-lean zones within the flame. It involves forced oscillation of the fuel and/or oxidant flow rates provided to the burner. FIG. 9 describes schematically this concept, for a system involving only fuel flow rate oscillations. The level of NOx formed in each zone is significantly lower than that which would occur if the combustion took place without fuel oscillation but at the same overall average fuel flow rate because in the oscillating case the combustion is achieved off-stoichiometry, thus at reduced temperature. When the fuel-rich and fuel-lean zones eventually mix in the furnace, after heat has been transferred from the flame to the load and the flame temperature is lower, the resulting burnout of combustible gases occurs with little additional NOx formation. Additionally, the increased flame luminosity resulting from the fuel-rich combustion zones combined with the increased turbulence created by the flow oscillations provide increased heat transfer to the furnace load. To achieve these results, the technology only requires that an oscillating valve package (valve+pulse controller) be installed on the fuel and/or oxidant supply line ahead of each burner. Thus, with minimal modifications to an existing combustion systems (compared to retrofits required by a staged burner or an over-fire air system) and if the combustion chamber design is appropriate (residence time, wall temperature . . . ), the above described conditions required for NO—NO2 conversion are perfectly met: in the region near the chamber exit, if the amplitude and frequency of the oscillations are adapted, the hot gases from the fuel-rich zone eventually mix with the gases from the previous fuel-lean zone. Since the air/fuel ratio is so far from the stoichiometry in this fuel-lean zone, barely any combustion occurs, thus keeping the oxidant at fairly low temperature. When the two zones eventually mix, the oscillations allow a turbulent mixing of hot combustion gases containing NO and substantially cold O2-containing gas, thus guaranteeing efficient NO to NO2 conversion. The phenomenon is even enhanced in the case of oscillating combustion since the fuel-rich periods are generating an additional supply of radicals and unburnt species (CO, H2 and hydrocarbons), resulting in higher levels of the HO2 radical which in turn results in higher levels of NO2 formation. A preferred combustion chamber configuration for the implementation of the oscillating combustion in the frame of this invention is a single-burner system, natural gas-fired where the load and the heat release rate create reduced wall and chamber exit temperatures. In this single-burner configuration, the amount of CO generated during fuel-rich oscillations does not usually have time to be burnt out by gases from fuel-lean zones. To keep CO emissions below regulated levels, a preferred solution is to implement a post-combustion system involving a recirculation zone positioned proximate to the main combustion zone and an injection zone positioned downstream from the recirculation zone, as described herein. With such a system, flue gases exiting the combustion chamber not only contain reduced levels of NOx compared to a conventional burner system, but the ratio NO2/NOx is also much higher than in prior art low NOx systems. This aspect is of great advantage since it provides the opportunity to combine this first combustion control technique with a simple and cost-effective post-treatment NOx removal system, such as a wet scrubbing system, as shown in FIG. 8. Any other system can also be implemented to remove the remaining NO and NO2 in the flue gas, but a preferred embodiment of this invention promotes the use of a system designed to capture only the NO2 generated during the combustion and not to oxidize or reduce the remaining NO into N2 or into a soluble species. A preferred system to remove the NO2 is a wet chemical scrubber using reagents such as NaOH (sodium hydroxide) and/or NaHS (sodium hydrosulfide) and/or Na2S (sodium sulfide). Other types of reagents can also be considered with different designs as far as packed bed depths, column velocities, recirculation rates, etc. A system based solely on water scrubbing is also possible, provided that enough room is available around the combustor to install such a large unit. But whatever the exact design selected, the unique advantage of this invention is to be able to remove almost all the NOx from the flue gas without the use of expensive reagents and catalysts like precious metals, ozone or ammonia usually required for the removal of NO. In a preferred configuration, this invention must allow a NOx reduction after the combustor of at least 30%, more preferably at least 50% and even more preferably at least 60%. The NO2/NOx ratio of this remaining amount of NOx should be at least 50%, preferably higher than 80% and even more preferably up to about 100%. By using a post-treatment system able to capture almost all of the NO2, it can then be concluded that this technology can reduce by close to 100% NOx emissions from certain favorable combustion processes. Preferably, this technology is able to reduce by at least 80% NOx from a conventional system, and to bring overall NOx emissions preferably below 10 ppm. Oscillating combustion has been implemented in a 1 MWt natural gas fired firetube boiler, along with a post-combustion system to avoid the emission of large amounts of CO. The boiler was equipped with an already low-NOx swirl-type burner. The burner was fired at a fuel flow rate of 2500 scfh and in the base case, without fuel oscillations, a NOx level of about 60 ppm (corrected at 3% O2) was measured, among which 57 ppm was NO. After installation of the fuel oscillating valve, the burner was fired at the same firing rate in average, but with fuel oscillations of various amplitudes and frequencies. With an amplitude of the oscillations at 70% (i.e., maximum fuel flow rate at 170% of average flow rate and minimum flow rate at 30% of the average flow) and a frequency of 1 Hz (1 fuel-rich zone and 1 fuel-lean zone generated every second), the NOx reduction achieved was about 53%, with a NO level of about 5 ppm (at 3% O2) and NO2 at about 22.5 ppm. By implementing a wet chemical NO2 scrubber in the flue gas exhaust of this boiler, with a NO2 removal efficiency of at least 95%, the final NOx level at the exit of the system described in this invention can be below 6 ppm, resulting in an overall NOx reduction of 90% compared to the baseline achieved by a conventional low-NOx burner. Such levels of NOx removal can compete with the most advanced ultra low NOx technologies, including ultra low NOx burners or SCR systems, but with lower capital and operating costs due to the simplicity of the technical concepts involved. While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention relates to a method for optimized post-combustion of CO and unburned hydrocarbons in combustion processes where low levels of NO x emissions are to be achieved. 2. Related Art High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce significant quantities of nitrogen oxides (NO x ) per unit of material processed. At the same time, regulations on emissions from industrial furnaces are becoming increasingly more stringent, especially in areas such as California. Consequently, there has been a demand for improved combustion technologies allowing reduction of NO x formation. Different solutions have been developed, usually based on the principle of either staged or diluted combustion. However, the operating conditions that favor the reduction of NO x emissions typically affect the combustion process itself such that combustion can become incomplete, thereby generating carbon monoxide (CO) and unburned hydrocarbons (HC). For this reason, and in order to achieve optimum emission performances, some of the low NO x technologies have had to be coupled with some sort of post-combustion system in order to remove CO and unburned HC from the flue gas before being exhausted into the atmosphere. The present invention relates to industrial combustion processes, including high-temperature furnaces, industrial boilers, and utility boilers, facing stringent NO x regulations. Because nitrogen oxides (primarily NO and NO 2 , hereafter NO x ) have been identified as a major cause of air pollution as well as a significant health hazard in ambient air, they have been defined as a criteria pollutant by the Clean Air Act Amendment (CAAA), which has established environmental limits in determined locations. To comply with these regulations, many U.S. combustion process operators have had to implement NO x control technologies in the past few years. This trend will most likely propagate in other areas and become even more pronounced. Widely implemented low NO x technologies included combustion techniques, allowing to significantly prevent the formation of NO x inside the combustion chamber, in contrast to post-treatment techniques (such as Selective Catalytic Reduction), where NO x is removed from flue gases through chemical reactions. Among these combustion-based NO x control technologies, many different techniques have been proposed and optimized, based on the following concepts: 1) reduction of the temperature in the combustion zone to limit NO x formation mechanism, 2) decrease of the oxygen concentration available for NO x formation in the high temperature zones, and/or 3) creation of conditions under which NO x can be reduced to molecular nitrogen by reacting with hydrocarbon fragments. One example of this general type of technology is low excess air, or reducing the available oxygen to the point which is just sufficient to oxidize the fuel but not so much as to cause emissions such as NO x , and CO (i.e. stoichiometric balance). Another example is staged combustion, or staging combustion by arranging the inlets of fuel or air to achieve off-stoichiometric firing conditions in the different zones of combustion. Still another example is flue gas recirculation (FGR), or recirculating the flue gas to the combustion zone as a diluent to reduce flame temperature and oxygen concentration. Another example is oscillating combustion, or oscillating the flow of fuel in order to create fuel-rich and fuel-lean combustion zones, and operating only under off-stoichiometric conditions. A final example is gas reburning, or introducing fuel gas to bum in the post combustion zone, generating hydrocarbon fragments which reduce the NO x formed in the main combustion zone to molecular nitrogen. Advantageous as the foregoing examples can be, they each suffer some drawbacks. When applied to minimize NO x production, these examples can affect the mixing of the reactants, generating instability in the combustion process, and eventually causing incomplete combustion. The result is the unwanted exhaust of CO and unburned hydrocarbons from the combustion system. This can be explained by the fact that CO and unburned hydrocarbon formation is dependent on the same three basic factors that influence NO x emissions: temperature, oxygen concentration and residence time at elevated temperatures. Unfortunately, each of these must be controlled in the opposite direction from that of NO x reduction: if all three factors are decreased, NO x production can be dramatically reduced but CO production is enhanced, and vice versa. As CO emissions can rarely be sacrificed for reduced NO x because low emission systems must keep both pollutants at a minimum, it is then necessary to implement a CO removal system downstream of the combustion region. Again two different approaches are basically available in the prior art: a first one, based on catalytic oxidation of CO in the flue gas exhaust section, at reduced temperature, and a second one, based on post-combustion of CO with an oxidant, inside or in the vicinity of the combustion chamber. A well known catalytic method is the Non-Selective Catalytic Reduction (NSCR), used in rich burn engines for simultaneous reduction of NO x , CO and volatile organic compounds. With this method, the engine is tuned to run richer so that there is a concurrent decrease in NO x and increase in reducing agents (CO and HC). Then downstream of the engine, in the presence of a catalyst and at reduced temperature, NO x react with CO, HCs or H 2 to produce nitrogen, carbon dioxide and water. If this method allows a combined reduction of the different pollutants, it can however be quite expensive, with the need for a tight process control system and a costly catalytic reactor that has to be replaced periodically. A similar system for gas-fired heating units is also presented in German Patent DE 4006735, issued to Ragert. Thus, a problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide a post-combustion system including at least one, and preferably a combination, of a flue gas recirculation zone, a flue gas mixing zone and an oxidant injection zone. Still another problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide a method that sufficiently increases the residence time of combustion products inside the combustion chamber, especially in regions where temperature is low enough to prevent the formation of NO x . Another problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide enhancement of the mixing of combustion products inside the combustion chamber in order to favor the completion of the combustion. An even further problem associated with high-temperature CO removal methods that precede the present invention is that they do not provide optimized post-combustion oxidant injection devices that distribute as evenly as possible this oxidant into the post-combustion zone. For the foregoing reasons, there has been defined a long felt and unsolved need for a method for efficiently and cost-effectively removing CO and unburned HC from the flue gas of low NO x combustion processes without re-creating substantial NO x emissions. | <SOH> SUMMARY OF THE INVENTION <EOH>A method for optimized post-combustion of CO and unburned hydrocarbons in combustion processes where low levels of NO x emissions are to be achieved is disclosed. The method is adaptable for use in many combustion processes, including industrial boilers, utility boilers and industrial furnaces. Through the proposed technique of post-combustion, CO emissions can be kept below regulated levels without regenerating additional NO x emissions. This post-combustion method is based on a combination of a recirculation zone of the combustion products, a flue gas mixing zone and finally, an oxidant injection zone, all designed to optimize the residence time, temperature range and mixing of the various reactants. In one preferred embodiment, this method and apparatus are associated with the technology of oscillating combustion, thus providing at the same time very low NO x emissions and CO emissions, in compliance with current regulations. A previous application of the assignee, U.S. patent application Ser. No. 10/310,197, filed Dec. 3, 2002, describes a process using the technology of oscillating combustion to reduce NO x emissions, which usually involve the simultaneous implementation of a post-combustion device so as to keep CO emissions below compliance levels. Tests have shown that the fine-tuning of such post-combustion techniques is very complicated and much of the NO x reduction achieved at flame level can be spoiled in this area if CO is not burned out in an appropriate manner. It is an object of the present invention to provide a post-combustion system including at least one, and preferably a combination, of a flue gas recirculation zone, a flue gas mixing zone and an oxidant injection zone. Yet another object of the present invention to provide a method that sufficiently increases the residence time of combustion products inside the combustion chamber, especially in regions where temperature is low enough to prevent the formation of NO x . Still another object of the present invention to provide enhanced mixing of combustion products inside the combustion chamber in order to favor the completion of the combustion. An even further object of the present invention to provide optimized post-combustion oxidant injection devices that distribute as evenly as possible this oxidant into the post-combustion zone. These and other objects, advantages and features of the present invention will be apparent from the detailed description that follows. | 20040324 | 20050705 | 20050203 | 58971.0 | 0 | GRAVINI, STEPHEN MICHAEL | METHOD AND APPARATUS FOR OPTIMIZED CO POST-COMBUSTION IN LOW NOX COMBUSTION PROCESSES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,808,846 | ACCEPTED | Modulation of gamma delta T cells to regulate airway hyperresponsiveness | Disclosed is a method for regulation of airway hyperresponsiveness by modulating the action of γδ T cells in a patient. Also disclosed are methods for identifying compounds that regulate airway hyperresponsiveness by modulating γδ T cell action. | 1. A method to reduce airway hyperresponsiveness in a mammal, comprising increasing γδ T cell action in a mammal that has, or is at risk of developing, a respiratory condition associated with airway hyperresponsiveness. 2. The method of claim 1, wherein said step of increasing γδ T cell action comprises increasing the number of γδ T cells in the lung tissue of said mammal. 3. The method of claim 2, wherein said step of increasing comprises removing γδ T cells from said mammal, inducing said γδ T cells to proliferate ex vivo to increase the number of said γδ T cells, and returning said γδ T cells to the lung tissue of said mammal. 4. The method of claim 1, wherein said step of increasing γδ T cell action comprises activating γδ T cells in said mammal. 5. The method of claim 4, wherein said step of activating γδ T cells is performed ex vivo. 6. The method of claim 1, wherein said step of increasing γδ T cell action comprises administering an agent to said mammal that activates γδ T cells in said mammal. 7-16. (Cancelled) 17. The method of claim 6, wherein said agent is targeted to γδ T cells in said mammal. 18. The method of claim 17, wherein said agent is targeted to γδ T cells in the lung tissue of said mammal. 19. The method of claim 17, wherein said agent is targeted to γδ T cells having a T cell receptor (TCR) selected from the group consisting of a murine TCR comprising Vγ4 and a human TCR comprising Vγ1. 20-21. (Cancelled) 22. The method of claim 6, wherein said agent is administered to the lung tissue of said mammal. 23. The method of claim 22, wherein said agent is administered by a route selected from the group consisting of inhaled, intratracheal and nasal routes. 24. The method of claim 6, wherein said agent is administered to said animal in an amount effective to reduce airway hyperresponsiveness in said animal as compared to prior to administration of said agent. 25. The method of claim 6, wherein said agent is administered with a pharmaceutically acceptable excipient. 26. The method of claim 1, wherein said γδ T cell action is increased within between about 1 hour and 6 days of an initial diagnosis of airway hyperresponsiveness in said mammal. 27. The method of claim 1, wherein said γδ T cell action is increased within less than about 72 hours of an initial diagnosis of airwayhyperresponsiveness in said mammal. 28. The method of claim 1, wherein said γδ T cell action is increased prior to development of airway hyperresponsiveness in said mammal. 29. The method of claim 1, wherein said step of increasing γδ T cell action decreases airway methacholine responsiveness in said mammal. 30-32. (Cancelled) 33. The method of claim 1, wherein said airway hyperresponsiveness is associated with a disease selected from the group consisting of chronic obstructive disease of the airways and asthma. 34. A method to identify a compound that reduces or prevents airway hyperresponsiveness associated with inflammation, comprising: a) contacting a putative regulatory compound with a γδ T cell; b) detecting whether said putative regulatory compound increases the action of said γδ T cell; c) administering said putative regulatory compound to a non-human animal in which airway hyperresponsiveness can be induced, and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of said putative regulatory compound; wherein a putative regulatory compound that increases γδ T cell action and that reduces or prevents airway hyperresponsiveness in said non-human animal is indicated to be a compound for reducing or preventing hyperresponsiveness. 35. The method of claim 34, wherein said step (b) of detecting is selected from the group consisting of measurement proliferation of said γδ T cell, measurement ofcytokine production by said γδ T cell, measurement ofcalcium mobilization in said γδ T cell, measurement of cytokine receptor expression by said γδ T cell, measurement of CD69 upregulation by said γδ T cell, measurement of upregulation of CD44 by said γδ T cell, and measurement of cytoskeletal reorganization by said γδ T cell. | CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 09/672,865, filed Sep. 28, 2000, which application claims priority under 35 U.S.C. § 119(e) from U.S. Provisional Application Ser. No. 60/157,231, filed Sep. 30, 1999, and entitled “Regulation of Airway Hyperresponsiveness by Modulation of y8 T Cells.” The entire disclosure of U.S. patent application Ser. No. 09/672,865 and U.S. Provisional Application Ser. No. 60/157,231 is incorporated herein by reference. GOVERNMENT RIGHTS This invention was made in part with government support under NIH Grant HL-36577, NIH Grant AI-40611 and NIH Grant AI-01291, all awarded by the National Institutes of Health. The government has certain rights to this invention. FIELD OF THE INVENTION The present invention generally relates to a method to regulate airway hyperresponsiveness by modulating the action of γδ T cells in a patient. The present invention further relates to methods for identifying compounds that regulate airway hyperresponsiveness by modulating γδ T cell action. BACKGROUND OF THE INVENTION Diseases involving inflammation are characterized by the influx of certain cell types and mediators, the presence of which can lead to tissue damage and sometimes death. Diseases involving inflammation are particularly harmful when they afflict the respiratory system, resulting in obstructed breathing, hypoxemia, hyperapnia and lung tissue damage. Obstructive diseases of the airways are characterized by airflow limitation (i.e., airflow obstruction or narrowing) due to constriction of airway smooth muscle, edema and hypersecretion of mucus leading to increased work in breathing, dyspnea, hypoxemia and hypercapnia. A variety of inflammatory agents can provoke airflow limitation including allergens, cold air, exercise, infections and air pollution. In particular, allergens and other agents in allergic or sensitized mammals (i.e., antigens and haptens) cause the release of inflammatory mediators that recruit cells involved in inflammation. Such cells include lymphocytes, eosinophils, mast cells, basophils, neutrophils, macrophages, monocytes, fibroblasts and platelets. Inflammation results in airway hyperresponsiveness (AHR). A variety of studies have linked the degree, severity and timing of the inflammatory process with the degree of airway hyperresponsiveness. Thus, a common consequence of inflammation is airway hyperresponsiveness. Currently, therapy for treatment of inflammatory diseases involving AHR, such as moderate to severe asthma and chronic obstructive pulmonary disease, predominantly involves the use of glucocorticosteroids and other anti-inflammatory agents. These agents, however, have the potential of serious side effect, including, but not limited to, increased susceptibility to infection, liver toxicity, drug-induced lung disease, and bone marrow suppression. Thus, such drugs are limited in their clinical use for the treatment of lung diseases associated with airway hyperresponsiveness. The use of anti-inflammatory and symptomatic relief reagents is a serious problem because of their side effects or their failure to attack the underlying cause of an inflammatory response. There is a continuing requirement for less harmful and more effective reagents for treating inflammation. Thus, there remains a need for processes using reagents with lower side effect profiles, less toxicity and more specificity for the underlying cause of AHR. Airway hyperresponsiveness (AHR) is the result of complex pathophysiological changes in the airway. A variety of studies have linked the degree, severity and timing of the inflammatory process with the degree of airway hyperresponsiveness. However, the mechanisms leading to AHR are still poorly understood and can be attributed to both immune-dependent and immune-independent mechanisms. Essentially all of the T cell-mediated effects described so far are in the former category. However, T cells from hyperresponsive mice can increase baseline airway tone in hyporesponsive mice after cell transfer. Because of their constitutive presence in the normal lung, γδ T cells have been investigated with regard to their potential role in airway responses. γδ T cells have been observed to proliferate and produce cytokines in many diseases. In addition, studies in animal models have provided evidence that these cells contribute to host resistance against infections (Hiromatsu et al., 1992, J. Exp. Med. 175:49), and that they can influence inflammation (Fu et al., 1994, J. Immunol. 153:3101), epithelial regeneration (Boismenu et al., 1994, Science 266:1253), and mucosal tolerance to antigens (Fujihashi et al., 1992, J. Exp. Med. 175:695; McMenamin et al., 1994, supra). Investigators are still determining what stimuli trigger γδ T cell reactivity, and to what extent γδ T cell activating stimuli differ from those of αβ T cells and B lymphocytes. It is known that γδ T cells respond during bacterial and viral infections, although they have not been readily linked to antigen-specific adaptive immunity. A number of studies have investigated the presence and role of γδ T cells in diseases of the airways. Pawankar et al. noted the mucosal changes at the site of allergic inflammation in patients with perennial allergic rhinitis and chronic infective rhinitis includes an oligoclonal expansion and activation of Vγ1/Vδ+ T cells (Pawankar and Ra, 1996, J. Allergy Clin. Immunol. 98:S248-62). Molfino et al. showed that much of the γδ T cell population found in broncho alveolar lavage (BAL) fluid in humans derives from clonally expanded T cells (Molfino et al., 1996, Clin. Exp. Iminunol. 104:144-153). Spinozzi et al., measuring γδ T cells in the BAL fluid from patients with asthma, concluded that allergen-specific, steroid-sensitive γδ T cells may be one of the cellular components involved in the airway inflammation that characterizes allergic bronchial asthma (Spinozzi et al., 1996, Ann. Intern. Med. 124:223-227 and 1995, Mol. Med. 1:821-826). Moreover, it has been noted that in patients with respiratory conditions including Bordetella pertussin infection (whooping cough) and asthma, circulating γδ T cells are decreased. It has been suggested that the reason for this decrease is the dispatch of γδ T cells to the site of inflammation in the lung. (Bertotto et al., 1997, Acta Paediatr. 86:114-115; Schauer et al., 1991, Clin. Exp. Immunol. 86:440-443; Krejsek et al., 1998, Allergy 53;73-77). Many of the studies directed to γδ T cells and airway diseases have directly suggested that γδ T cells are proinflammatory, promoting acute airway sensitization, increases in cytokine levels suggested to be involved in allergic inflammation, regulation of allergic αβ T-cell and allergen specific B-cell responses, and/or allergen-induced eosinophilia and IgE responses (e.g., McMenamin et al., 1994, Science 265:1869-1871; Zuany-Amorim et al., 1998, supra; Schramm et al., 2000, Am. J. Respir. Cell Mol. Biol. 22:218-225; Schramm et al., 1999, International Conference of the American Thoracic Society; vol. 159:A255 (American Journal of Respiratory and Critical Care Medicine, San Diego, Calif.)). Some investigators, alternatively, have concluded that γδ T cells do not play a significant role in airway allergic inflammation. For example, Chen et al. noted, similar to other investigators discussed above, that allergic asthmatics have reduced γδ T cells in the peripheral blood. However, Chen et al. concluded that no significant correlation existed between the levels of γδ T cells and IgE present in the peripheral blood (Chen et al., 1996, Clin. Exp. Iminunol. 26:295-302). Although allergic asthmatics have reduced γδ T cells with reciprocally elevated eosinophil numbers in the peripheral blood, Chen et al. asserted that this does not indicate that the reduction of γδ T cells correlates with the predominance of eosinophilia or IgE levels in diseased populations. Jaffar et al. described a role for au, but not γδ, T cells in allergen-induced Th2 cytokine production from asthmatic bronchial tissue (Jaffar et al., 1999, J. Immunol. 163:6283-6291). Fajac et al., 1997, Eur. Resp. J 10:633-638 investigated the role of heat shock proteins and γδ T cells in patients with mild atopic asthma, and concluded that neither heat shock proteins nor γδ T cells play an important role in inflammatory and immune responses in mild asthma. Therefore, prior to the present invention, those of skill in the art either considered γδ T cells to play an insignificant role, if any, in diseases of the airways, or believed that γδ T cells were proinflammatory cells which contributed to the development of acute airway hyperresponsiveness and other events associated with inflammation. SUMMARY OF THE INVENTION The present inventors have discovered that yb cells can regulate airway function in an aid T cell-independent manner, identifying them as important cells in pulmonary homeostasis. This function of γδ T cells differs from previously described immune-dependent mechanisms and may reflect their interaction with innate systems ofhost defense. Specifically, in contrast to other studies that emphasized their role in the modification of allergen-specific αβ T cell and B-cell responses, the present inventors have found that γδ T cells maintain normal airway responsiveness independently of αβ T cells. One embodiment of the present invention relates to a method to reduce airway hyperresponsiveness in a mammal. The method includes the step of increasing γδ T cell action in a mammal that has, or is at risk of developing, a respiratory condition associated with airway hyperresponsiveness. In one aspect, the step of increasing γδ T cell action comprises increasing the number of γδ T cells in the lung tissue of the mammal. For example, the step of increasing can comprise removing γδ T cells from the mammal, inducing the γδ T cells to proliferate ex vivo to increase the number of the γδ T cells, and returning the γδ T cells to the lung tissue of the mammal. In another aspect, the step of increasing γδ T cell action comprises activating γδ T cells in the mammal. Activating γδ T cells can be performed ex vivo or in vivo. In one embodiment of the method, the step of increasing γδ T cell action comprises administering an agent to the mammal that activates γδ T cells in the mammal. Such an agent can be any agent suitable for activating γδ T cells. In one aspect, the agent is a protein comprising a BiP-binding motif, wherein the protein is administered in an amount effective to induce proliferation of γδ T cells in the mammal. In another aspect, the agent is selected from the group consisting of a glycosylated protein and a glycosylated peptide. In another aspect, the agent is selected from the group consisting of polyGT and poly GAT (1:1:1). In yet another embodiment, the agent is selected from the group of: synthetic GC, synthetic AT and other oligonucleotides. In yet another aspect, the agent is a mycobacterial product. In another aspect, the agent is a Listeria cell wall product. In another aspect, the agent is a cardiolipin. In yet another aspect, the agent is tumor necrosis factor-α (TNF-α). In one aspect, the agent is an antibody that specifically binds to a γδ T cell receptor and activates the γδ T cells. Preferably, the agent is an antibody that specifically binds to a γδ T cell receptor (TCR) from a γδ T cell subset that is particularly suitable for regulation of airway hyperresponsiveness. Such a TCR includes, but is not limited to, a murine TCR comprising Vγ4 and a human TCR comprising Vγ1. In one aspect of the method of the present invention, the agent is targeted to γδ T cells in the mammal. Preferably, the agent is targeted to γδ T cells in the lung tissue of the mammal. In one embodiment, the agent is targeted to γδ T cell subsets that are particularly suitable for regulation of airway hyperresponsiveness, such γδ T cells having a T cell receptor (TCR) selected from: a murine TCR comprising Vγ4 and a human TCR comprising Vγ1. In one aspect, the agent comprises: (a) an antibody that specifically binds to a molecule on the cell surface of γδ T cells; and (b) a compound that activates the γδ T cells, wherein the compound is linked to the antibody of (a). The compound can include, but is not limited to: a protein comprising a peptide having a BiP-binding motif, a glycosylated protein or peptide, polyGT, polyGAT (1:1:1), synthetic GC, synthetic AT, a mycobacterial product, a Listeria cell wall product, cardiolipin, TNF-α, and an antibody that specifically binds to a γδ T cell receptor and activates the receptor. In one aspect of the present method, the agent is administered to the lung tissue of the mammal. In a preferred embodiment, the agent is administered by a route selected from the group consisting of inhaled, intratracheal and nasal routes. Preferably, the agent is administered to the animal in an amount effective to reduce airway hyperresponsiveness in the animal as compared to prior to administration of the agent. In one aspect, the agent is administered with a pharmaceutically acceptable excipient. Preferably, the method of the present invention increases γδ T cell action within between about 1 hour and 6 days of an initial diagnosis of airway hyperresponsiveness in the mammal. In another embodiment, the γδ T cell action is increased within less than about 72 hours of an initial diagnosis of airway hyperresponsiveness in the mammal. In another embodiment, the γδ T cell action is increased prior to development of airway hyperresponsiveness in the mammal. Preferably, the step of increasing γδ T cell action decreases airway methacholine responsiveness in the mammal, and/or reduces airway hyperresponsiveness of the mammal such that the FEV1 value of the mammal is improved by at least about 5%. It is also preferred that the step of increasing γδ T cell action improves the mammal's PC20methacholinFEV1 value such that the PC20methacholineFEVI value obtained before the step of increasing γδ T cell action when the mammal is provoked with a first concentration of methacholine is substantially the same as the PC20methacholinFEV1 value obtained after increasing γδ T cell action when the mammal is provoked with double the amount of the first concentration of methacholine. Preferably, the first concentration of methacholine is between about 0.01 mg/ml and about 8 mg/ml. The method of the present invention is suitable for treating airway hyperresponsiveness associated with any condition including, but not limited to, airway hyperresponsiveness is associated with a disease selected from the group consisting of chronic obstructive disease of the airways and asthma. Yet another embodiment of the present invention relates to a method to identify a compound that reduces or prevents airway hyperresponsiveness associated with inflammation. The method includes the steps of: (a) contacting a putative regulatory compound with a γδ T cell; (b) detecting whether the putative regulatory compound increases the action of the γδ T cell; and, (c) administering the putative regulatory compound to a non-human animal in which airway hyperresponsiveness can be induced, and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of the putative regulatory compound. A putative regulatory compound that increases γδ T cell action and that reduces or prevents airway hyperresponsiveness in the non-human animal is indicated to be a compound for reducing or preventing hyperresponsiveness. Preferably, step (b) of detecting is selected from the group consisting of measurement proliferation of the γδ T cell, measurement of cytokine production by the γδ T cell, measurement of calcium mobilization in the γδ T cell, measurement of cytokine receptor expression by the γδ T cell, measurement of.CD69 upregulation by the γδ T cell, measurement of upregulation, of CD44 by the γδ T cell, and measurement of cytoskeletal reorganization by the γδ T cell. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a line graph showing changes in airway resistance (RL) in normal C57BL/6 mice after systemic airway sensitization, aerosol only airway sensitization, and no treatment. FIG. 1B is a line graph showing changes in airway resistance (RL) in TCR-δ−\− mice, TCR-β−\− mice and normal C57BL/6 after systemic airway sensitization. FIG. 1C is a line graph showing changes in airway resistance (RL) in TCR-δ-depleted or sham-depleted BALB/c mice after systemic airway sensitization. FIG. 1D is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in C57BL/6 mice, TCR-δ−\− mice and TCR-β−\− mice after systemic airway sensitization. FIG. 2A is a line graph showing changes in airway resistance (RL) in C57BL/6 mice, TCR-δ−\− mice and TCR-β−\− mice after aerosol only airway sensitization. FIG. 2B is a line graph showing changes in dynamic compliance (Cdyn) in C57BL/6 mice, TCR-δ−\− mice and TCR-β−/− mice after aerosol only airway sensitization. FIG. 2C is a line graph showing changes in airway resistance (RL) in sham-depleted C57BL/6 mice and γδ T cell-depleted C57BL/6 mice after aerosol only airway sensitization. FIG. 2D is a line graph showing changes in dynamic compliance (Cdyn) in sham-depleted C57BL/6 mice and γδ T cell-depleted C57BL/6 mice after aerosol only airway sensitization. FIG. 2E is a line graph showing changes in airway resistance (RL) sham-depleted BALB/c mice and γδ T cell-depleted BALB/c mice after aerosol only airway sensitization. FIG. 2F is a line graph showing changes in dynamic compliance (Cdyn) sham-depleted BALB/c mice and γδ T cell-depleted BALB/c mice after aerosol only airway sensitization. FIG. 2G is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in C57BL/6 mice, TCR-δ−\− mice and TCR-β−\− mice after aerosol only airway sensitization. FIG. 2H is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in sham-depleted C57BL/6 mice and γδ T cell-depleted C57BL/6 mice after aerosol only airway sensitization. FIG. 2I is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in sham-depleted BALB/c mice and γδ T cell-depleted BALB/c mice after aerosol only airway sensitization. FIG. 3A is a line graph showing changes in airway resistance (RL) in sham-depleted TCR-βb−\− mice and γδ-depleted TCR-β−\− mice after aerosol only airway sensitization. FIG. 3B is a line graph showing changes in dynamic compliance (Cdyn) in sham-depleted TCR-β−\− mice and y8-depleted TCR-β−\− mice after aerosol only airway sensitization. FIG. 3C is a line graph showing changes in airway resistance (RL) in sham-depleted TCR-β−\− mice and αβ-depleted TCR-β−\− mice after aerosol onlyairway sensitization. FIG. 3D is a line graph showing changes in dynamic compliance (Cdyn) in sham-depleted TCR-β−\− mice and αβ-depleted TCR-β−\− mice after aerosol only airway sensitization. FIG. 3E is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in sham-depleted TCR-β−\− mice and y8-depleted TCR-β−\− mice after aerosol only airway sensitization. FIG. 3F is a bar graph showing BAL fluid cell composition for total cells, eosinophils and macrophages in sham-depleted TCR-β−\− mice and ap-depleted TCR-β−\− mice after aerosol only airway sensitization. FIG. 4A is a graph showing serum levels of OVA-specific IgG1 in C57BL/6 mice, TCRβ−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. FIG. 4B is a graph showing serum levels of OVA-specific IgE n C57BL/6 mice, TCR-β−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. FIG. 4C is a graphshowing serum levels of OVA-specific IgG2a in C57BL/6 mice, TCR-β−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. FIG. 5A is a bar graph showing BAL fluid IL-5 levels in C57BL/6 mice, TCR-β−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. FIG. 5B is a bar graph showing BAL fluid IL-4 levels in C57BL/6 mice, TCR-β−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. FIG. 5C is a bar graph showing BAL fluid IFN-γ levels in C57BL/6 mice, TCR-β−\− mice, and TCR-δ−\− mice after aerosol only and systemic airway sensitization. DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a method to reduce or prevent airway hyperresponsiveness (AHR) in an animal that has, or is at risk of developing, airway hyperresponsiveness, by increasing the action of γδ T cells (i.e., γδ T lymphocytes) in the animal. In the method of the present invention, the animal has, or is at risk of developing, airway hyperresponsiveness associated with inflammation. For example, airway hyperresponsiveness is commonly associated with allergic inflammation and/or viral-induced inflammation. Airway hyperresponsiveness associated with allergic inflammation can occur in a patient that has, or is at risk of developing, a condition including, but not limited to, any chronic obstructive disease of the airways. Such conditions include, but are not limited to: asthma, chronic obstructive pulmonary disease, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonia, eosinophilic pneumonia, emphysema, bronchitis, allergic bronchitis bronchiectasis, cystic fibrosis, tuberculosis, hypersensitivity pneumonitis, occupational asthma, sarcoid, reactive airway disease syndrome, interstitial lung disease, hyper-eosinophilic syndrome, rhinitis, sinusitis, exercise-induced asthma, pollution-induced asthma and parasitic lung disease. Airway hyperresponsiveness associated with viral-induced inflammation can occur in a patient that has, or is at risk of developing, an infection by a virus including, but not limited to, respiratory syncytial virus (RSV), parainfluenza virus (PIV), rhinovirus (RV) and adenovirus. The present invention is based on the present inventors' discovery that γδ T cells maintain normal airway responsiveness independently of αβ T cells and that the increased action of γδ T cells in patient's that have, or are at risk of developing, airway hyperresponsiveness will have a beneficial effect. To define the role of γδ T cells in controlling the development of AHR, the present inventors used an established mouse model of eosinophilic airway inflammation and allergen-driven alterations in airway function. The results of this research demonstrated a previously unknown, γδ T cell-dependent mechanism in the regulation of airway responsiveness which is independent of αβ T cells and their allergen-specific responses. Furthermore, the present inventors' have found no evidence to indicate that antibodies are involved in this regulatory mechanism or that changes in cytokine levels previously suggested to be involved in models allergic inflammation are involved (McMenamin et al., 1994, Science 265:186-1871; Zuany-Amorim et al., 1998, supra). The present inventors' discovery was surprising, because the results differ from earlier reports, which have emphasized the role of γδ T cells in regulating allergic αβ T-cell and allergen specific B-cell responses, or their role in promoting allergen-induced eosinophilia and IgE responses (McMenamin et al., 1994, supra; Zuany-Amorim et al., 1998, supra; Schramm et al., 1999, International Conference of the American Thoracic Society; vol. 159:A255 (American Journal of Respiratory and Critical Care Medicine, San Diego, Calif.)). The mechanism of γδ T cell-dependent regulation of airway responses described herein is therefore not restricted to allergic inflammation. One embodiment of the present invention relates to a method to reduce or prevent airway hyperresponsiveness in an animal. This method includes a step of increasing γδ T cell action in a mammal that has, or is at risk of developing, a respiratory condition associated with airway hyperresponsiveness. According to the present invention, “airway hyperresponsiveness” or “AHR” refers to an abnormality of the airways that allows them to narrow too easily and/or too much in response to a stimulus capable of inducing airflow limitation. AHR can be a functional alteration of the respiratory system caused by inflammation or airway remodeling (e.g., such as by collagen deposition). Airflow limitation refers to narrowing of airways that can be irreversible or reversible. Airflow limitation and/or airway hyperresponsiveness can be caused by collagen deposition, bronchospasm, airway smooth muscle hypertrophy, airway smooth muscle contraction, mucous secretion, cellular deposits, epithelial destruction, alteration to epithelial permeability, alterations to smooth muscle function or sensitivity, abnormalities of the lung parenchyma and/or infiltrative diseases in and around the airvays. Many of these causative factors can be associated with inflammation. The present invention is directed to any airway hyperresponsiveness, including airway hyperresponsiveness that is associated with inflammation of the airways, eosinophilia and inflammatory cytokine production. Methods of measuring and monitoring AHR are discussed in detail below. As used herein, to reduce airway hyperresponsiveness refers to any measurable reduction in airway hyperresponsiveness and/or any reduction of the occurrence or frequency with which airway hypertesponsiveness occurs in a patient. A reduction in AHR can be measured using any of the above-described techniques or any other suitable method known in the art. Preferably, airway hyperresponsiveness, or the potential therefore, is reduced, optimally, to an extent that the animal no longer suffers discomfort and/or altered function resulting from or associated with airway hyperresponsiveness. To prevent airway hyperresponsiveness refers to preventing or stopping the induction of airway hyperresponsiveness before biological characteristics of airway hyperresponsiveness as discussed above can be substantially detected or measured in a patient. AHR can be measured by a stress test that comprises measuring an animal's respiratory system function in response to a provoking agent (i.e., stimulus). AHR can be measured as a change in respiratory function from baseline plotted against the dose of a provoking agent (a procedure for such measurement and a mammal model useful therefore are described in detail below in the Examples). Respiratory function can be measured by, for example, spirometry, plethysmograph, peak flows, symptom scores, physical signs (i.e., respiratory rate), wheezing, exercise tolerance, use of rescue medication (i.e., bronchodialators) and blood gases. In humans, spirometry can be used to gauge the change in respiratory function in conjunction with a provoking agent, such as methacholine or histamine. In humans, spirometry is performed by asking a person to take a deep breath and blow, as long, as hard and as fast as possible into a gauge that measures airflow and volume. The volume of air expired in the first second is known as forced expiratory volume (FEV1) and the total amount of air expired is known as the forced vital capacity (FVC). In humans, normal predicted FEV1 and FVC are available and standardized according to weight, height, sex and race. An individual free of disease has an FEV, and a FVC of at least about 80% of normal predicted values for a particular person and a ratio of FEV1/FVC of at least about 80%. Values are determined before (i.e, representing a mammal's resting state) and after (i.e., representing a mammal's higher lung resistance state) inhalation of the provoking agent. The position of the resulting curve indicates the sensitivity of the airways to the provoking agent. The effect of increasing doses or concentrations of the provoking agent on lung function is determined by measuring the forced expired volume in 1 second (FEV1) and FEV1 over forced vital capacity (FEV1/FVC ratio) of the mammal challenged with the provoking agent. In humans, the dose or concentration of a provoking agent (i.e., methacholine or histamine) that causes a 20% fall in FEV1 (PD20FEV1) is indicative of the degree of AHR. FEV1 and FVC values can be measured using methods known to those of skill in the art. Pulmonary function measurements of airway resistance (RL) and dynamic compliance (Cdyn or CL) and hyperresponsiveness can be determined by measuring transpulmonary pressure as the pressure difference between the airway opening and the body plethysmograph. Volume is the calibrated pressure change in the body plethysmograph and flow is the digital differentiation of the volume signal. Resistance (RL) and compliance (CL) are obtained using methods known to those of skill in the art (e.g., such as by using a recursive least squares solution of the equation of motion). The measurement of lung resistance (RL) and dynamic compliance (CL) are described in detail in the Examples. It should be noted that measuring the airway resistance (RL) value in a non-human mammal (e.g., a mouse) can be used to diagnose airflow obstruction similar to measuring the FEV1 and/or FEV1/FVC ratio in a human. A variety of provoking agents are useful for measuring AHR values. Suitable provoking agents include direct and indirect stimuli. Preferred provoking agents include, for example, an allergen, methacholine, a histamine, a leukotriene, saline, hyperventilation, exercise, sulfur dioxide, adenosine, propranolol, cold air, an antigen, bradykinin, acetylcholine, a prostaglandin, ozone, environmental air pollutants and mixtures thereof. Preferably, Mch is used as a provoking agent. Preferred concentrations of Mch to use in a concentration-response curve are between about 0.001 and about 100 milligram per milliliter (mg/ml). More preferred concentrations of Mch to use in a concentration-response curve are between about 0.01 and about 50 mg/ml. Even more preferred concentrations of Mch to use in a concentration-response curve are between about 0.02 and about 25 mg/ml. When Mch is used as a provoking agent, the degree of AHR is defined by the provocative concentration of Mch needed to cause a 20% drop of the FEV1 of a mammal (PC20methacholineFEV1). For example, in humans and using standard protocols in the art, a normal person typically has a PC20methacholineFEV1>8 mg/ml of Mch. Thus, in humans, AHR is defined as PC20methacholineFEV1<8 mg/ml of Mch. According to the present invention, respiratory function can also be evaluated with a variety of static tests that comprise measuring an animal's respiratory system function in the absence of a provoking agent. Examples of static tests include, for example, spirometry, plethysmographically, peak flows, symptom scores, physical signs (i.e., respiratory rate), wheezing, exercise tolerance, use of rescue medication (i.e., bronchodialators) and blood gases. Evaluating pulmonary function in static tests can be performed by measuring, for example, Total Lung Capacity (TLC), Thoracic Gas Volume (TgV), Functional Residual Capacity (FRC), Residual Volume (RV) and Specific Conductance (SGL) for lung volumes, Diffusing Capacity of the Lung for Carbon Monoxide (DLCO), arterial blood gases, including pH, PO2 and PCO2 for gas exchange. Both FEV1 and FEV1/FVC can be used to measure airflow limitation. If spirometry is used in humans, the FEV1 of an individual can be compared to the FEV1 of predicted values. Predicted FEV1 values are available for standard normograms based on the animal's age, sex, weight, height and race. A normal animal typically has an FEV1 at least about 80% of the predicted FEV1 for the animal. Airflow limitation results in a FEV1 or FVC of less than 80% of predicted values. An alternative method to measure airflow limitation is based on the ratio of FEV1 and FVC (FEV1/FVC). Disease free individuals are defined as having a FEV1/FVC ratio of at least about 80%. Airflow obstruction causes the ratio of FEV1/FVC to fall to less than 80% of predicted values. Thus, an animal having airflow limitation is defined by an FEV1/FVC less than about 80%. In one embodiment, the method of the present invention decreases methacholine responsiveness in the animal. Preferably, the method of the present invention results in an improvement in a mammal's PC20methacholineFEV1 value such that the PC20methacholineFEV1 value obtained before use of the present method when the mammal is provoked with a first concentration of methacholine is the same as the PC20methacholineFEV1 value obtained after use of the present method when the mammal is provoked with double the amount of the first concentration of methacholine. Preferably, the method of the present invention results in an improvement inma mammal's PC20methacholineFEV1 value such that the PC20mcthacholineFEV1 value obtained before the use of the present method when the animal is provoked with between about 0.01 mg/ml to about 8 mg/ml of methacholine is the same as the PC20methacholineFEV, value obtained after the use of the present method when the animal is provoked with between about 0.02 mg/ml to about 16 mg/ml of methacholine. In another embodiment, the method of the present invention improves an animal's FEV1 by at least about 5%, and more preferably by between about 6% and about 100%, more preferably by between about 7% and about 100%, and even more preferably by between about 8% and about 100% of the mammal's predicted FEV1. In another embodiment, the method of the present invention improves an animal's FEV1 by at least about 5%, and preferably, at least about 10%, and even more preferably, at least about 25%, and even more preferably, at least about 50%, and even more preferably, at least about 75%. In yet another embodiment, the method of the present invention results in an increase in the PC20methacholineFEV1 of an animal by about one doubling concentration towards the PC20methacholineFEV1 of a normal animal. A normal animal refers to an animal known not to suffer from or be susceptible to abnormal AHR. A patient, or test animal refers to an animal suspected of suffering from or being susceptible to abnormal AHR. Therefore, an animal that has airway hyperresponsiveness is an animal in which airway hyperresponsiveness is measured or detected, such as by using one of the above methods for measuring airway hyperresponsiveness. To be associated with inflammation, the airway hyperresponsiveness is apparently or obviously, directly or indirectly associated with (e.g., caused by, a symptom of, indicative of, concurrent with) an inflammatory condition or disease (i.e., a condition or disease characterized by inflammation). Typically, such an inflammatory condition or disease is at least partially characterized by inflammation of pulmonary tissues. Such conditions or diseases are discussed above. An animal that is at risk of developing airway hyperresponsiveness can be an animal that has a condition or disease which is likely to be associated with at least a potential for airway hyperresponsiveness, but does not yet display a measurable or detectable characteristic or symptom of airway hyperresponsiveness. An animal that is at risk of developing airway hyperresponsiveness also includes an animal that is identified as being predisposed to or susceptible to such a condition or disease. Inflammation is typically characterized by the release of inflammatory mediators (e.g., cytokines or chemokines) which recruit cells involved in inflammation to a tissue. For example, a condition or disease associated with allergic inflammation is a condition or disease in which the elicitation of one type of immune response (e.g., a Th2-type immune response) against a sensitizing agent, such as an allergen, can result in the release of inflammatory mediators that recruit cells involved in inflammation in a mammal, the presence of which can lead to tissue damage and sometimes death. Airway hyperresponsiveness associated with allergic inflammation can occur in a patient that has, or is at risk of developing, any chronic obstructive disease of the airways, including, but not limited to, asthma, chronic obstructive pulmonary disease, allergic bronchopulmonary asp ergillosis, hypersensitivity pneumonia, eosinophilic pneumonia, emphysema, bronchitis, allergic bronchitis bronchiectasis, cystic fibrosis, tuberculosis, hypersensitivity pneumonitis, occupational asthma, sarcoid, reactive airway disease syndrome, interstitial lung disease, hyper-eosinophilic syndrome, rhinitis, sinusitis, exercise-induced asthma, pollution-induced asthma and parasitic lung disease. Preferred conditions to treat using the method of the present invention include asthma, chronic obstructive disease of the airways, occupational asthma, exercise-induced asthma, pollution-induced asthma and reactive airway disease syndrome, with chronic obstructive disease of the airways and asthma being particularly preferred for treatment. Viral-induced inflammation typically involves the elicitation of another type of immune response (e.g., a Th1-type immune response) against viral antigens, resulting in production of inflammatory mediators the recruit cells involved in inflammation in a an animal, the presence of which can also lead to tissue damage. Aiiway hyperresponsiveness associated with viral-induced inflammation can occur in a patient that has, or is at risk of developing, an infection by a virus including, but not limited to, respiratory syncytial virus (RSV), parainflulenza virus (PIV), rhinovirus (RV) and adenovirus. In order to reduce airway hypeiresponsiveness according to the method of the present invention, the action of γδ T cells is increased in an animal that has, or is at risk of developing AHR, including AHR associated with inflammation. A “γδ T cell” is a distinct lineage of T lymphocytes found in mammalian species and birds that expresses a particular antigen receptor (i.e., T cell receptor or TCR) that includes a γ chain and a δ chain. The γ and δ chains are distinguished from the α and β chains that make up the TCR of the perhaps more commonly referenced T cells known as “αβ T cells”. The γδ heterodimer of the γδ T cells is expressed on the surface of the T cell and, like the αβ heterodimer of αβ T cells, is associated with the CD3 complex on the cell surface. The γ and δ chains of the γδ T cell receptor should not be confused with the γ and δ chains of the CD3 complex. According to the present invention, the terms “T lymphocyte” and “T cell” can be used interchangeably herein. According to the present invention, to increase the action of γδ T cells in an animal refers to any treatment or manipulation of the animal, or specifically, of γδ T cells, which results in a detectable (e.g., measurable) increase (i.e., enhancement, upregulation, induction, stimulation) in the number, activation, biological activity and/or survivability of the γδ T cells. Therefore, increasing the action of γδ T cells according to the present invention can be accomplished by increasing the number of γδ T cells in an animal (i.e., by causing the cells to proliferate/expand or by recruiting additional γδ T cells to a site), by increasing the activation of γδ T cells in an animal, by increasing biological activity of γδ T cells (e.g., effector functions or other activities of the cell) in an animal and/or by increasing the ability of γδ T cells to survive (i.e., resist apoptosis) in an animal. According to the present invention, to increase the action of γδ T cells in an animal further refers to a step of directly acting on γδ T cells in the animal. In other words, the method of increasing the action of γδ T cells directly expands, recruits, activates, or enhances survival of γδ T cells, even though other cell types might be affected by the method, but such step is not intended to be merely a downstream result of a direct action on another cell type. Preferably, and particularly when the method is performed in vivo, the step of increasing the action of γδ T cells does not substantially directly affect (i.e., act on) other cells, such as αβ T cells, B cells, macrophages, or monocytes. In this case, selective or targeted methods for increasing γδ T cells are preferred. The increased action of γδ T cells can subsequently affect other cells, however, such as alveolar macrophages, airway epithelial and airway smooth muscle cells (i.e., increased numbers and/or activity of γδ T cells can influence the activity of other cells). It will be appreciated by those of skill in the art that when the step of increasing the action of γδ T cells is performed ex vivo or in vitro, the step of increasing γδ T cell action does not necessarily have to be selective for or targeted to γδ T cells, but preferably, γδ T cells are subsequently isolated and/or preferentially returned to the animal. Therefore, in the preferred embodiment, the method of the present invention is intended to be selective for or specifically targeted to γδ T cell activity, and in one embodiment, excludes methods which indiscriminately activate other immune system cells and/or other cell types, as well as methods which modulate γδ T cell activity as a downstream result of a direct action on another cell type. More specifically, in one embodiment, an increase in γδ T cell action is defined herein as any detectable increase in the number of γδ T cells in a population (clonal or non-clonal) of γδ T cells. According to the present invention, an increase in the number of γδ T cells at a given site can be accomplished by: (1) causing a given population of γδ T cells to proliferate and expand; (2) inducing recruitment of additional γδ T cells to a given site, such that the total number of γδ T cells increases; and/or (3) adding additional γδ T cells to a population of T cells (e.g., T cell transfer). An increase in the number of γδ T cells is typically evaluated by measuring proliferation of γδ T cells, for example, by using a standard T cell proliferation assay (e.g., uptake of [3H]-thymidine). T cell proliferation assays, including those using γδ T cells, are well known in the art, and are described, for example, in several publications by certain of the present inventors (e.g., Born et al., 1990, Science 249:67; O'Brien et al., 1992, Proc. Natl. Acad. Sci. USA 89:4348; Lahn et al., 1998, J. Immunol. 160:5221; Cady et al., 2000, J. Immunol. 165:1790; all incorporated herein by reference in their entireties). Other methods for determining an increase in the number of γδ T cells can be evaluated by detecting or measuring the expression level, and/or the distribution of γ-chain usage and/or δ chain usage in the receptors of a population of γε T cells and determining whether there is a change in the expression level and/or distribution of one or more γδ T cell receptor types in the population. Such assays, including both molecular and flow cytometric methods, and the reagents (e.g., antibodies, hybridization probes and PCR primers specific for various γδ TCR chains) for performing such assays, are known in the art (e.g., O'Brien et al., 1992, supra; Lahn et al., 1998, supra; Cady et al., 2000, supra). In another embodiment, an increase in γδ T cell action is any detectable increase in the activation state and/or biological activity of γε T cells in an animal. As used herein, activation, or responsiveness, of a γδ T cell refers to the ability of a γδ T cell to be activated by (e.g., respond to) antigenic and/or mitogenic stimuli which results in induction of γδ T cell activation signal transduction pathways and activation events. The biological activity of a γδ T cell refers to any function(s) exhibited or performed by a naturally occurring γδ T cell as measured or observed in vivo (i.e., in the natural physiological environment of the cell) or in vitro (i.e., under laboratory conditions). As used herein, antigenic stimulation is stimulation of a γδ T cell by binding of the γδ T cell receptor to an antigen that is specifically recognized by the γδ T cell in the context of appropriate costimulatory signals necessary to achieve γδ T cell activation. Mitogenic stimulation is defined herein as any non-antigen stimulation of T cell activation, including by mitogens (lipopolysaccharides (LPS), phorbol esters, ionomycin) and antibodies (anti-TCR, anti-CD3, including divalent and tetravalent antibodies). Both antigenic stimulation and the forms of mitogenic stimulation which act at the level of the T cell receptor (i.e., anti-TcR/CD3) result in T cell receptor-mediated activation, whereas LPS/phorbol ester/ionomycin mitogenic stimulation bypasses the T cell receptor and therefore, do not induce T cell receptor-mediated activation, but nonetheless, can induce at least some of the downstream events of T cell activation. Therefore, events associated with T cell activation or biological activity include, but are not limited to, T cell proliferation, cytokine production (e.g., interleukin-2 (IL-2), IL-4, IL-5, IL-10, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α)), upregulation of cytokine receptors (e.g., IL-2 receptor, TNF-α receptor), calcium mobilization, upregulation of cell surface molecules associated with T cell activation (e.g., CD44, CD69), upregulation of expression and activity of signal transduction proteins associated with T cell activation, chemokine production, altered T cell migration, accumulation of T cells at specific tissue sites and/or cytoskeletal reorganization. The ability of a T lymphocyte to respond, or become activated, by an antigenic or mitogenic stimulus can be measured by any suitable method of measuring T cell activation. Such methods are well known to those of skill in the art. For example, after a T cell has been stimulated with an antigenmc or mitogenic stimulus, characteristics of T cell activation can be determined by a method including, but not limited to: measuring cytokine production by the T cell (e.g., by immunoassay or biological assay); measuring intracellular and/or extracellular calcium mobilization (e.g., by calcium mobilization assays); measuring T cell proliferation (e.g., by proliferation assays such as radioisotope incorporation); measuring upregulation of cytokine receptors on the T cell surface, including IL-2R (e.g., by flow cytometry, immunofluorescence assays, immunoblots, RNA assays); measuring upregulation of other receptors associated with T cell activation on the T cell surface (e.g., by flow cytometry, immunofluorescence assays, immunoblots, RNA assays); measuring reorganization of the cytoskeleton (e.g., by immunofluorescence assays, immunoprecipitation, immunoblots); measuring upregulation of expression and activity of signal transduction proteins associated with T cell activation (e.g., by kinase assays, phosphorylation assays, immunoblots, RNA assays); and, measuring specific effector functions of the T cell (e.g., by proliferation assays). Methods for performing each of these measurements are well known to those of ordinary skill in the art, many are described in detail or by reference to publications herein, and all such methods are encompassed by the present invention. In another embodiment, an increase in γδ T cell action results in an increase in the survival of the γδ T cell (i.e., prevention or inhibition of apoptosis). According to the present invention, the present method preferably results in a measurable maintenance of γδ T lymphocyte survival (e.g., less than about 50%, and more preferably, less than about 25%, and more preferably, less than about 10%, and even more preferably, less than about 5% loss in blood γδ T lymphocyte number after employing the present method as compared to in the absence of the present method). T lymphocyte survival can be determined by measuring any of the parameters described above for measuring T cell proliferation/numbers or activation (as an indicator of responsive T cells), or by any suitable means of measuring T cell apoptosis (i.e., a reduction in γδ T cell apoptosis is indicative of enhanced γδ T cell survival). Methods of measuring apoptosis in a T cell include, but are not limited to: determining the extent of a morphological change in a cell; determining the extent of DNA cleavage by gel electrophoresis, cell cycle analysis, or in situ tailing or nick translation; assessing membrane permeability by using dyes that bind RNA or DNA or Annexin V. Such methods are well known in the art. According to the present invention, the method for regulating airway hyperresponsiveness can be directed to any γδ T cell, wherein an increase in the action of such γδ T cell results in a decrease in airway hyperresponsiveness. Preferred γδ T cells to activate and/or expand (i.e., proliferate, increase the numbers) are γδ T cells in the lung tissue of an animal. Such γδ T cells include γδ T cells that normally reside in the lung tissue, as well as γδ T cells that are recruited into the lung upon development of a condition associated with airway hyperresponsiveness and/or upon stimulation of γδ T cells that normally reside in the lung tissue. Preferably, the present method includes a step of increasing γδ T cell action in γδ T cells that normally reside in the lung tissue. In another preferred embodiment, the method for regulation of airway hyperresponsiveness of the present invention is directed to γδ T cells that are identified as being particularly useful for regulating AHR in an animal, wherein increased action of γδ T cells that do not regulate AHR, or which are proinflammatory (i.e., contribute to AHR), is avoided. In one aspect, a preferred γδ T cell for which increasing the action is believed to be particularly effective for reducing AHR has a T cell receptor (TCR) that comprises a Vγ4 chain (i.e., the variable (V) region of the γ chain is has a particular sequence which is known in the art as Vγ4, following the nomenclature of Tonegawa et al., for example), or the human equivalent thereof, which is believed to include Vδ1 T cells (i.e., Vγ4 is the murine cell subset). Preferably, γδ T cells having TCRs with Vγ4 chains, or the human equivalent (e.g., Vδ1), are targeted by the method of the present method. This subset of γδ T cells can be targeted, for example, by using a targeting moiety that selectively recognizes the Vγ4 chain of the TCR (e.g., an antibody that selectively binds to Vγ4) (or the Vb 1 chain of the TCR in humans, for example), or by removing cells from the lung tissue (or other tissues) and isolating γδ T cells expressing Vγ4 (or human equivalent) ex vivo. In yet another preferred embodiment, γδ T cells that are CD8+ (i.e., which express CD8) are preferred targets for the method of the present invention. Even more preferably, γδ T cells which express an αβ heterodimer of CD8 are preferably selectively targeted for activation and/or expansion according to the present method. CD8 is a costimulatory molecule expressed by subsets of both αβ T lymphocytes and γδ T lymphocytes. The CD8 molecule comprises two chains which can occur in the form of either a dimer of CD8α chains (i.e., a CD8α homodimer) or a dimer of a CD8α chain and a CD8β chain (i.e., a CD8 at heterodimer). In αβ T cells, the CD8 molecule is typically expressed as a CD8 αβ heterodimer. In contrast, in γδ T cells, the CD8 molecule is typically expressed as a CD8 α homodimer. However, the present inventors have found that a subset of γδ T cells in the lung expresses CD8 as a CD8 αβ heterodimer. Moreover, the present inventors have found that a subset of Vγ4+ T cells in the murine lung express the CD8 αβ heterodimer. Without being bound by theory, the present inventors believe that γδ T cells expressing a CD8 αβ heterodimer, and particularly γδ T cells expressing Vγ4 (or the human equivalent such as V81) and a CD8 αβ heterodimer, are particularly suitable targets for the method of the present invention and are likely to be at least one primary regulatory γδ T cell subset that contributes to the reduction of AHR in vivo. In another embodiment of the present invention, the method for regulation of ainvay hyperresponsiveness of the present invention is further directed to the inhibition of γδ T cells that are identified as being particularly enhancing of AHR in an animal, wherein decreased action of these γδ T cells that do not control AHR, and/or which are proinflammatory (i.e., contribute to AHR), is the goal. Without being bound by theory, the present inventors believe that certain subsets of γδ T cells appear to be enhancing of AHR and therefore, their targeted ablation would be beneficial in the treatment of AER. In particular, the present inventors have discovered that γδ T cells bearing a T cell receptor comprising a Vγ1 chain for murine cells (or the human equivalent, such as Vγ9NV52 expressing cells), which appear later than the regulatory Vγ1 subset discussed above, may enhance AHR. More specifically, it is believed that the CD4+ Vγ1+ γδ T cell subset (or the human equivalent thereof) is a particularly desirable target for inhibition by the method of the present invention. Therefore, in one embodiment of the present invention, either alone or in combination with the stimulation of Vγ4+T cells (or the human equivalent thereof) according to the present method, Vγ1+ T cells (or the human equivalent thereof) are inhibited. Methods for inhibition will be clear to those of skill in the art and include, but are not limited to targeted destruction of Vγ1+ T cells (or the human equivalent thereof) (e.g., by neutralizing antibodies, induced apoptosis), blocking of such TCRs by blocking antibodies (i.e., that do not stimulate the T cell), anti-sense therapy, and other such methods. It is to be understood, however, that it is not necessary to selectively target a particular subset of γδ T cells to reduce AHR in an animal, as methods of increasing the action of γδ T cells which do not selectively target a particular subset are also effective for reducing AHR. For example, in one embodiment, γδ T cell activation that is effective for reducing AHR can be selectively targeted or enhanced by increasing γδ T cell action relatively early after airw % ay hyperresponsiveness (or initial antigen sensitization leading to AHR) is induced. Without being bound by theory, the present inventors believe that the γδ T cell responses which are effective to downregulate AHR are most effective within between about 1 hour to about 6 days after AHR is induced, and most preferably, within less than about 72 hours after AHR is induced. As discussed above, it is further believed that γδ T cells which may enhance AIHR appear later in the response, and could be avoided by early targeting, or actively ablated by later targeted delivery of γδ T cell inhibitors. Alternatively, by selectively targeting γδ T cells expressing Vγ4 (or the human equivalent thereof), the timing of the treatment may be effective at later timepoints. Other methods for directing the method of the present invention to γδ T cells, including to specific subsets of γδ T cells are discussed below. Accordingly, the method of the present invention can be carried out by any suitable process of increasing the numbers, activation or biological activity, or survival of γδ T ciells, wherein increased action of γδ T cells is effective to reduce airway hyperresponsiveness in a mammal. Such a process can be performed in vivo, such as by administration of a compound to an animal which increases the action of γδ T cells in the animal or by transferring γδ T cells into an animal from another source. Alternatively, such a process can be performed ex vivo, such as by removing a sample of cells, tissues or bodily fluids from an any suitable tissue or region in an animal which includes γδ T cells; expanding, activating and/or selecting (isolating) γδ T cells in vitro to increase the number and/or action of γδ T cells in the sample; and returning at least the γδ T cells to the lung tissue of the animal. In one embodiment, the method of the present invention includes the use of a variety of agents (i.e., regulatory compounds) which, by acting on γδ T cells, increase the proliferation, activationibiological activity, and/or survival of γδ T cells in the lung tissue of an animal, and/or the recruitment of other regulatory γδ T cells to the lung tissue of the animal, such that airway hyperresponsiveness is reduced in the animal. Such agents are generally referred to herein as γδ T cell agonists. According to the present invention, a γδ T cell agonist is any agent which increases, typically by direct action on the cell, the proliferation, activationibiological activity, and/or survival of γδ T cells, and includes agents which act directly on the γδ T cell receptor. A γδ T cell agonist, as referred to herein, can further include, for example, compounds that are products of rational drug design, natural products, and compounds having partially or fully defined γδ T cell stimulatory properties. A γδ T cell agonist can be a protein-based compound, a carbohydrate-based compound, a lipid-based compound, a nucleic acid-based compound, a natural organic compound, a synthetically derived organic compound, an antibody, or fragments thereof A variety of known γδ T cell agonists are described below and all are encompassed by the present invention. In one embodiment, γδ T cells are selectively stimulated by random heterocopolymers of glutamic acid and tyrosine, generally referred to herein as polyGT. polyGT is most commonly known as a randomly synthesized heterocopolymeric peptide composed of glutamic acid and tyrosine, with an average length of 100 amino acids and a capacity to elicit strong immune responses in certain mouse strains. As described in detail in Cady et al. (2000, J Immunol. 165:1790), polyGT stimulates polyclonal proliferation of normal (e.g., splenic) γδ T cells as well as hybridomas, but not an cells. Therefore, polyGT is useful for selectively stimulating γδ T cells in the absence of stimulating αβ T cells, and in the absence of additional targeting of the polyGT to γδ T cells. According to the present invention, polyGT can be provided as a synthetic peptide, such as polyGlu50Tyr50 (publicly available from Sigma, P-0151), as a random heterocopolymer of glutamic acid and tyrosine of any other length which is sufficient to elicit a γδ T cell response (i.e., stimulation, activation), and by several natural proteins which contain such repeats, including predicted and actual proteins in bacteria, viruses, mice and humans. Such sequences, and the proteins containing such sequences, can be readily identified by performing simple sequence searches in the public sequence databases. Such peptides are simple to produce and test for γδ T cell stimulation, using methods formeasuring γδ T cell stimulation as described elsewhere herein and in Cady et al., ibid., which is incorporated herein by reference in its entirety. In another embodiment, a peptide referred to a polyGAT (1:1:1) is also stimulatory for γδ T cells and can be used in the present method. PolyGAT is a synthetic peptide that is comprised of glutamic acid, alanine and tyrosine in a 1:1:1 ratio. The peptide was named prior to the now universally standard single letter code for amino acids. Yet another γδ T cell agonist includes synthetic AT and other oligonucleotides (i.e., nucleic acid sequences having from about 5 to about 100 nucleotides, and more preferably from about 5 to about 50, and more preferably from about 5 to about 30 nucleotides). Synthetic AT is an oligonucleotide of at least 5 nucleotides composed of adenosine and tbymidine. Other types of oligonucleotides, including those composed of guanine and cytosine, are also stimulatory for γδ T cells. Shorter oligonucleotides (less than 20 nucleotides) stimulate only when immobilized (e.g., on any suitable substrate) or otherwise polymerized. In one embodiment of the present invention, the agent used for increasing γδ T cell action is an antibody. In one aspect, the antibody selectively binds to a γδ T cell in a manner such that the γδ T cell proliferation, survival or activation is increased. In a preferred aspect, the antibody selectively binds to the γδ T cell receptor (γδ TCR) and activates the γδ T cell by such binding. In one aspect, the antibody selectively binds to a specific subset of γδ T cell receptors which are identified as being particularly effective to reduce airway hyperresponsiveness in an animal. In a particularly preferred embodiment, the antibody binds to a γδ T cell receptor expressing a Vγ4 chain. As used herein, the term “selectively binds to” refers to the ability of antibodies of the present invention to preferentially bind to specified proteins (e.g., a γδ T cell receptor). Binding can be measured using a variety of methods standard in the art including enzyme immunoassays (e.g., ELISA), immunoblot assays, radioimmunoassays, etc. Several antibodies which selectively bind to a γδ T cell receptor are known in the art and are publicly available. Such antibodies include, but are not limited to: anti-TCR-8 (GL3, GL4 and UC7-13D5 (PharMingen, San Diego, Calif.); or 403.A10); anti-mouse TCR-Vγ1 (2.11); anti-TCR-Vγ4 (UC3-10A6; PharMingen, San Diego, Calif.). Isolated antibodies of the present invention can include serum containing such antibodies, or antibodies that have been purified to varying degrees. Antibodies of the present invention can be polyclonal or monoclonal, functional equivalents such as antibody fragments (e.g., Fab fragments or Fab2 fragments) and genetically-engineered antibodies, including single chain antibodies or chimeric antibodies, including bi-specific antibodies that can bind to more than one epitope. Generally, in the production of an antibody, a suitable experimental animal, such as a rabbit, hamster, guinea pig or mouse, is exposed to an antigen against which an antibody is desired. Typically, an animal is immunized with an effective amount of antigen that is injected into the animal. An effective amount of antigen refers to an amount needed to induce antibody production by the animal. The animal's immune system is then allowed to respond over a pre-determined period of time. The immunization process can be repeated until the immune system is found to be producing antibodies to the antigen. In order to obtain polyclonal antibodies specific for the antigen, serum is collected from the animal that contains the desired antibodies. Such serum is useful as a reagent. Polyclonal antibodies can be further purified from the serum by, for example, treating the serum with ammonium sulfate. In order to obtain monoclonal antibodies, the immunized animal is sacrificed and B lymphocytes are recovered from the spleen. The differentiating and proliferating daughter cells of the B lymphocytes are then fused with rmyeloma cells to obtain a population of hybridoma cells capable of continual growth in suitable culture medium. Hybridomas producing a desired antibody are selected by testing the ability of an antibody produced by a hybridoma to bind to the antigen. Methods of producing both polyclonal and monoclonal antibodies of a desired specificity are well known in the art. Another agent that is particularly useful for increasing the action of γδ T cells includes a protein or peptide having a corresponding to a consensus motif that has been identified as being bound by the molecular chaperone known as BiP. This consensus motif is described in detail in Blond-Elguindi et al., 1993, Cell 75:717-728, incorporated herein by reference in its entirety. More particularly, the molecular chaperone, BiP, is the sole member of the HSP70 family localized in the endoplasmic reticulum. BiP is required for translocation fo newly synthesized proteins across the ER membrane and for their subsequent folding and assembly in the ER lumen. The role of BiP as chaperone depends on its ability to recognize a wide variety of nascent polypeptides that share no obvious sequence similarity, while discriminating between properly folded and unfolded structures. Blond-Elguindi et al. identified a heptameric consensus motif shared by peptides bound by BiP which can be used to predict and identify BiP-binding sites in natural proteins. It is the peptides consisting essentially of these BiP-binding sites, including such peptides found in various mycobacteria and bacteria, which, without being bound by theory, the present inventors believe may be particularly stimulatory for γδ T cells. As set forth in Blond-Elguindi, the BiP binding motif is best set forth as Hy(W/X)HyXHyXHy, where Hy is a large hydrophobic amino acid (most frequently Trp, Leu or Phe), W is Trp, and X is any amino acid. This core motif is of the size determined previously to fill the peptide-binding pocket of BiP (Flynn et al., 1991, Science 245:385). Additionally, the following amino acid tendencies at various positions have been observed: Gln is enriched at positions 4 and 8; Met, Gly and Thr are enriched at position 3; Asn, Ser and Tyr are enriched at position 5; and His, Ile, Pro and Thr are enriched at position 7. The present inventors have found that several peptides having this motif are capable of stimulating γδ T cell responses. Such peptides include the peptide identified by SEQ ID NO:1 which has the amino acid sequence denoted FALQLEL. This sequence is an artificial sequence that the present inventors have modified from a mycobacterial HSP-60 protein (from M. leprae) (i.e., FGLQLEL, SEQ ID NO:2), both of which the present inventors have identified as being stimulatory for γδ T cells. SEQ ID NO: 1 was generated by the present inventors to better stimulate γδ T cell hybridomas (Fu et al., 1994, J. Imnunol. 152:1578). Additional peptides having the BiP binding motif from other organisms, including other mycobacteria, bacteria, yeast, and mammals (human and mouse) have proven to be stimulatory for γδ T cells (data not shown herein). Such peptides, and proteins comprising such peptides in a form which is accessible to the γδ T cell receptor, are encompassed by the present invention for use in increasing the action of γδ T cells. According to the present invention, peptides suitable for stimulation of γδ T cells are at least about seven amino acids in length, and can include peptides of at least about 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acids. In one embodiment, a stimulatory consisting essentially of a given specified peptide (i.e., a peptide having the BiP peptide-binding motif) can include up to about 10 additional amino acids on either side of the BiP-binding motif. A protein comprising a suitable yoT cell stimulatory peptide is not restricted in size, but must have the ability to increase γδ T cell action as described herein. Yet another agent that is useful for increasing the action of γδ T cells according to the present invention is tumor necrosis factor-α (TNF-α). The present inventors have previously described that TNF-α is a particularly effective mediator of γδ T cell activation (See Lahn et al., 1998, supra). Specifically, investigating very early T cell activation in mouse and human models ofbacterial infection, the present inventors measured early cellular activation of T cells and found that, while both murine αβ and γδ T cells responded polyclonally to systemic bacterial infections and to lipopolysaccharides (LPS), γδ T cells responded more strongly to the bacteria and to LPS. The present inventors then identified tumor necrosis factor α (TNF-α) as the mediator of the early differential T cell activation, and of differential proliferative responses. The stronger response of γδ T cells to TNF-α was correlated with higher expression levels of TNF-Rp75, suggesting that this TNF-R determines the differential T cell reactivity. These data indicated that TNF-α is an early preferential activator of γδ T cells, connecting γδ T cell functions with those of cells that produce this cytokine, including activated innate effector cells and antigen-stimulated T lymphocytes. Now, the present inventors have additionally demonstrated that TNF-α negatively modulates (i.e., reduces or controls) airway hyperresponsiveness by activating γδ T cells. These results are described in detail in Example 6. Therefore, one embodiment of the present invention comprises increasing the action of γδ T cells in an animal by administering to the animal TNF-α. In one embodiment, the TNF-α is administered to the lung tissue of an animal. In a preferred embodiment, the TNF-α is targeted to γδ T cells in vivo or ex vivo by one of the methods of selectively targeting γδ T cells as described elsewhere herein. Other agents useful for increasing the action of γδ T cells include various compounds that can be associated with bacteria and/or viruses. Such compounds include, but are not limited to: glycosylated proteins or peptides, mycobacterial products, and Listeria cell wall products. It is known that γδ T cells respond during bacterial and viral infections. Additionally, in two mouse models of infection with the facultative intracellular bacterium Listeria monocytogenes, depletion of γδ T cells resulted in prolonged and exacerbated inflammation of the target organs, which underwent extensive tissue destruction (Fu et al., supra; Mombaerts et al., 1993, Nature 365:53; Mukasa et al., 1995, J Immunol. 155:2047). Depletion of αβ T cells did not have the same consequences, despite comparable or increased bacterial loads. Similar findings were also recently reported in a mouse model of lung infection with Mycobacterium tuberculosis (D'Souza et al., 1997, J Jmmunol. 158:1217). It has not been resolved whether γδ T cell reactivity in these infections is directly dependent on antigen recognition by these cells, or instead is merely driven by the innate and adaptive host responses to the bacteria, although stimulation of γδ T cells by bacterial components has been well documented (Haas et al., 1993, Annu. Rev. Immunol. 11:637). Particularly strong γδ T cell responses have been noted after infection of mice with certain Gram-negative bacteria, including Escherichia coli and Salmonella strains (Takad a et al., 1993, J. Immunol. 151:2062; Emoto et al., 1992, J. Exp. Med. 176:363; Mixter et al., 1994, Infect. Immun. 62:4618). Although it is controversial whether γδ T cells contribute to host protection against these pathogens (Weintraub et al., 1997, Infect. Immun. 65:2306), it has been demonstrated that γδ T cells can be stimulated by lipopolysaccharides (LPS) (Skeen et al., 1993, J. Exp. Med. 178:971; Reardon et al., 1995, J. Invest. Dermatol. 105:585; Tsuji et al., 1996, Int. Immunol. 8:359). The present inventors have recently found that γδ T cells responded more strongly to two types of systemic bacterial infection and to LPS than did ad T cells (Lahn et al., 1998, J. Immunol. 160:5221). Finally, the present inventors have also previously demonstrated that γδ T cell hybridomas respond in vitro to mycobacterial proteins, including portions of the mycobacterial heat shock protein HSP65. Without being bound by theory, the present inventors believe that the activation of γδ T cells by this protein may be related to the presence of a BiP-binding motif as discussed above. To the extent that portions (i.e., peptides) of the mycobacterial heat shock proteins, and particularly, portions of the mycobacterial HSP-60 family proteins, stimulate γδ T cells and through this action reduce AHR, such proteins or the portions thereof are encompassed as useful agents by the present invention. In another embodiment, γδ T cell agonists can include cardiolipin. Cardiolipin is a phospholipid that selectively stimulates γδ T cell hybridomas but not αβ T cell hybridomas. Most other phospholipids tested by the present inventors have not been stimulatory, although phosphatidyl-glycerol is weakly stimulatory and therefore, this phospholipid, or an improved homologue thereof, may also be useful in the present invention. For the activation of γδ T cells, the present invention also includes the use of “phospho-antigens”. Phospho-antigens are antigens containing phosphate groups such as isoprenylpyrophosphate (IPP) and many others that have been characterized by the research groups of Michael Brenner and others (e.g., Tanaka et al., 1995, Nature 375:155-158). Yet another γδ T cell stimulatory agent includes carbin alkylamines, including those that are present in microbes, edible plants and Tea (Bukowski et al., 1999, Immunity 11:57-65). In one embodiment, γδ T cell agonists of the present invention include products of drug design, including peptides, oligonucleotides, carbohydrates and/or synthetic organic molecules which regulate the proliferation, activation/biological activity, and/or survival of γδ T cells. Such an agent can be obtained, for example, from molecular diversity strategies (a combination of related strategies allowing the rapid construction of large, chemically diverse molecule libraries), libraries of natural or synthetic compounds, in particular from chemical or combinatorial libraries (i.e., libraries of compounds that differ in sequence or size but that have the same building blocks) or by rational drug design. See for example, Maulik et al., 1997, Molecular Biotechnology: Therapeutic Applications and Strategies, Wiley-Liss, Inc., which is incorporated herein by reference in its entirety. Candidate compounds initially identified by drug design methods can be screened for γδ T cell stimulatory activity and an ability to reduce AHR by increasing the action of γδ T cells using the methods described elsewhere herein. In a molecular diversity strategy, large compound libraries are synthesized, for example; from peptides, oligonucleotides, carbohydrates and/or synthetic organic molecules, using biological, enzymatic and/or chemical approaches. The critical parameters in developing a molecular diversity strategy include subunit diversity, molecular size, and library diversity. The general goal of screening such libraries is to utilize sequential application of combinatorial selection to obtain high-affinity ligands against a desired target, and then optimize the lead molecules by either random or directed design strategies. Methods of molecular diversity are described in detail in Maulik, et al., stipra. In a rational drug design procedure, the three-dimensional structure of a regulatory compound can be analyzed by, for example, nuclear magnetic resonance (NMR) or X-ray crystallography. This three-dimensional structure can then be used to predict structures of potential compounds, such as potential regulatory agents by, for example, computer modeling. The predicted compound structure can be used to optimize lead compounds derived, for example, by molecular diversity methods. In addition, the predicted compound structure can be produced by, for example, chemical synthesis, recombinant DNA technology, or by isolating a mimetope from a natural source (e.g., plants, animals, bacteria and fungi). Various other methods of structure-based drug design are disclosed in Maulik et al., 1997, supra. Maulik et al. disclose, for example, methods of directed design, in which the user directs the process of creating novel molecules from a fragment library of appropriately selected fragments; random design, in which the user uses a genetic or other algorithm to randomly mutate fragments and their combinations while simultaneously applying a selection criterion to evaluate the fitness of candidate ligands; and a grid-based approach in which the user calculates the interaction energy between three dimensional receptor structures and small fragment probes, followed by linking together of favorable probe sites. In one embodiment, additional regulators γδ T cells can be identified by using high-throughput screening methods, including DNA arrays. In accordance with the present invention, acceptable protocols to administer an agent (i.e., an agent/compound that increases γδ T cell activation), including the route of administration and the effective amount of an agent to be administered to an animal, can be determined and accomplished by those skilled in the art. An agent of the present invention can be administered in vivo or ex vivo. Suitable in vivo routes of administration can include, but are not limited to, oral, nasal, inhaled, topical, intratracheal, transdenial, rectal, and parenteral routes. Preferred parenteral routes can include, but are not limited to, subcutaneous, intradermal, intravenous, intramuscular, and intraperitoneal routes. Preferred topical routes include inhalation by aerosol (i.e., spraying) or topical surface administration to the skin of a mammal. Most preferably, an agent is administered to the lung tissue of an animal. Routes suitable for delivery of an agent to the lung tissue include, but are not limited to: nasal, inhaled, intratracheal, or intravenous routes. Most preferably, an agent is administered to an animal by nasal, inhaled, or intratracheal routes. Ex vivo refers to performing part of the administration step outside of the patient, such as by removing cells from a patient, culturing such cells in vitro to increase γδ T cell action, and returning the cells, or a subset thereof (e.g., isolated γδ T cells) to the patient. Ex vivo methods are particularly useful because the γδ T cells in the lung of the patient can be isolated from other cells in vitro, and expanded/activated prior to return of the cells to the lung of the patient. Therefore, it is not necessary to specifically isolate γδ T cells from a patient, but rather, a tissue, cell population and/or bodily fluid containing γδ T cells can be initially isolated, followed by stimulation of the cells by yb-specific or non-specific methods of T cell stimulation. Either prior to or subsequent to such stimulation, if desired, the γδ T cells can be isolated for return to the patient as a substantially homogeneous γδ T cell population in which γδ T cell action has been increased. It is noted, however, that separation of the γδ T cells from the other cells removed from the patient is not required and in some circumstances, may not be desirable (e.g., other cells removed from the patient might be valuable as being positively affected by γδ T cell activation). In this instance, γδ T cells can be selectively activated and/or expanded ex vivo, and returned to the patient with the other cells. Preferably, in an ex vivo method, the sample containing the γδ T cells to be manipulated is obtained from the lung tissue of the patient. Methods for obtaining cells from and returning cells to the lung of an animal, including bronchoalveolar lavage, are well known in the art. In addition, as described above, methods for manipulating γδ T cells ex vivo (i.e., iii vitro) are also well known in the art. According to the method of the present invention, an effective amount of a agent that increases γδ T cell action (also referred to simply as “an agent”) to administer to an animal comprises an amount that is capable of reducing airway hyperresponsiveness (AHR) without being toxic to the mammal. An amount that is toxic to an animal comprises any amount that causes damage to the structure or function of an animal (i.e., poisonous). In one embodiment, the effectiveness of an agent that increases γδ T cell action to protect an animal from AHR in an animal having or at risk of developing AHR can be measured in doubling amounts. For example, the ability of an animal to be protected from AHR (i.e., experience a reduction in or a prevention of) by administration of a given γδ T cell agonist is significant if the animal's PC20methacholineFEV1 is at 1 mg/ml before administration of the γδ T cell agonist and is at 2 mg/ml of Mch after administration of the γδ T cell agonist. Similarly, a γδ T cell agonist is considered to be effective if the animal's PC20methacholineFEV1 is at 2 mg/ml before administration of the γδ T cell agonist, and is at 4 mg/ml of Mch after administration of the γδ T cell agonist. Methods for measuring an animal's PC20methacholineFEV1 have been described above and are well known in the art. In one embodiment of the present invention; in an animal that has AHR, an effective amount of an agent to administer to an animal is an amount that measurably reduces AHR in the animal as compared to prior to administration of the agent. In another embodiment, an effective amount of an agent to administer to an animal is an amount that measurably reduces AHR in the animal as compared to a level of airway AJR in a population of animals with inflammation that is associated with AHR wherein the agent was not administered. In one embodiment of the present invention, an effective amount of an agent to administer to an animal includes an amount that is capable of decreasing methacholine responsiveness without being toxic to the animal. A preferred effective amount of an agent comprises an amount that is capable of increasing the PC20methacholineFEV1 of an animal treated with the an agent by about one doubling concentration towards the PC20methacholineFEV1 of a is normal animal. A normal animal refers to an animal known not to suffer from or be susceptible to abnormal AHR. A test animal refers to an animal suspected of suffering from or being susceptible to abnormal AHR. In another embodiment, an effective amount of an agent according to the method of the present invention, comprises an amount that results in an improvement in an animal's PC20methacholineFEV1 value such that the PC20methacholineFEV1 value obtained before administration of the an agent when the animal is provoked with a first concentration of methacholine is the same as the PC20methacholineFEV1 value obtained after administration of the an agent when the animal is provoked with double the amount of the first concentration of methacholine. A preferred amount of an agent comprises an amount that results in an improvement in an animal's PC20methacholineFEV1 value such that the PC20methacholineFEV1 value obtained before administration of the an agent is between about 0.01 mg/ml to about 8 mg/ml of methacholine is the same as the PC20methacholineFEV1 value obtained after administration of the an agent is between about 0.02 mg/ml to about 16 mg/ml of methacholine. As previously described herein, the effectiveness of an agent to protect an animal having or susceptible to AHR can be determined by measuring the percent improvement in FEV1 and/or the FEV1/FVC ratio before and after administration of the agent. In one embodiment, an effective amount of an agent comprises an amount that is capable of reducing the airflow limitation of an animal such that the FEV1/FVC value of the animal is at least about 80%. In another embodiment, an effective amount of an agent comprises an amount that is capable of reducing the airflow limitation of an animal such that the FEV1/FVC value of the animal is improved by at least about 5%, or at least about 100 cc or PGFRG 10 L/min. In another embodiment, an effective amount of an agent comprises an amount that improves an animal's FEV1 by at least about 5%, and more preferably by between about 6% and about 100%, more preferably by between about 7% and about 100%, and even more preferably by between about 8% and about 100% (or about 200 ml) of the animal's predicted FEV1. In another embodiment, an effective amount of an agent comprises an amount that improves an animal's FEV1 by at least about 5%, and preferably, at least about 10%, and even more preferably, at least about 25%, and even more preferably, at least about 50%, and even more preferably, at least about 75%. It is within the scope of the present invention that a static test can be performed before or after administration of a provocative agent used in a stress test. Static tests have been discussed in detail above. A suitable single dose of an agent that increases γδ T cell action (i.e., a γδ T cell agonist) to administer to an animal is a dose that is capable of reducing or preventing airway hyperresponsiveness in an animal when administered one or more times over a suitable time period. In particular, a suitable single dose of an agent comprises a dose that improves AHR by a doubling dose of a provoking agent or improves the static respiratory function of an animal. A preferred single dose of an agent typically comprises between about 0.01 microgram×kilogram−1 and about 10 milligram×kilogram−1 body weight of an animal. A more preferred single dose of an agent comprises between about 1 microgram×kilogram−1 and about 10 milligram×kilogram−1 body weight of an animal. An even more preferred single dose of an agent comprises between about 5 microgram×kilograms' and about 7 milligram×kilogram−1 body weight of an animal. An even more preferred single dose of an agent comprises between about 10 microgram×kilograms' and about 5 milligram×kilograms' body weight of an animal. A particularly preferred single dose of an agent comprises between about 0.1 milligram×kilograms and about 5 milligram×kilograms body weight of an animal, if the an agent is delivered by aerosol. Another particularly preferred single dose of an agent comprises between about 0.1 microgram×kilograms−1 and about 10 microgram×kilogram−1 body weight of an animal, if the agent is delivered parenterally. These doses particularly apply to the administration of protein agents, antibodies, and/or small molecules (i.e., the products of drug design). In one embodiment, the agent is administered with a pharmaceutically acceptable carrier, which includes pharmaceutically acceptable excipients and/or delivery vehicles, for administering the agent to a patient (e.g., a chimeric antibody or a liposome delivery vehicle). As used herein, a pharmaceutically acceptable carrier refers to any substance suitable for delivering an agent useful in the method of the present invention to a suitable in viivo or ex vivo site. Preferred pharmaceutically acceptable carriers are capable of maintaining an agent of the present invention in a form that, upon arrival of the agent in the animal and/or at a target γδ T cell, the agent is capable of interacting with its target (i.e., the γδ T cell) such that AHR is reduced or prevented. Suitable excipients of the present invention include excipients or formularies that transport or help transport, but do not specifically target an agent to a cell (also referred to herein as non-targeting carriers). Examples of pharmaceutically acceptable excipients include, but are not limited to water, phosphate buffered saline, Ringer's solution, dextrose solution, serum-containing solutions, Hank's solution, other aqueous physiologically balanced solutions, oils, esters, glycols and dry-powder inhalers. Aqueous carriers can contain suitable auxiliary substances required to approximate the physiological conditions of the recipient, for example, by enhancing chemical stability and isotonicity. Suitable auxiliary substances include, for example, sodium acetate, sodium chloride, sodium lactate, potassium chloride, calcium chloride, and other substances used to produce phosphate buffer, Tris buffer, and bicarbonate buffer. Auxiliary substances can also include preservatives, such as thimerosal,—or o-cresol, formalin and benzol alcohol. Compositions of the present invention can be sterilized by conventional methods and/or lyophilized. One type of pharmaceutically acceptable carrier includes a controlled release formulation that is capable of slowly releasing a composition of the present invention into an animal. As used herein, a controlled release formulation comprises an agent of the present invention in a controlled release vehicle. Suitable controlled release vehicles include, but are not limited to, biocompatible polymers, other polymeric matrices, capsules, microcapsules, microparticles, bolus preparations, osmotic pumps, diffusion devices, liposomes, lipospheres, and transdermal delivery systems. Suitable delivery vehicles include, but are not limited to liposomes, viral vectors or other delivery vehicles, including ribozymes. Natural lipid-containing delivery vehicles include cells and cellular membranes. Artificial lipid-containing delivery vehicles include liposomes and micelles. A delivery vehicle of the present invention can be modified to target to a particular site in a patient, thereby targeting and making use of an agent at that site. Suitable modifications include manipulating the chemical formula of the lipid portion of the delivery vehicle and/or introducing into the vehicle a targeting agent (e.g., an antibody) capable of specifically targeting a delivery vehicle to a preferred site (e.g., a γδ T cell). Other suitable delivery vehicles include gold particles, poly-L-lysine/DNA-molecular conjugates, and artificial chromosomes. In one embodiment, when the route of delivery is inhaled, a composition or agent of the present invention can be delivered by an inhaler device. A pharmaceutically acceptable carrier which is capable oftargeting is herein referred to as a “delivery vehicle.” Delivery vehicles of the present invention are capable of delivering a formulation, including an agent that increases the action of γδ T cells, to a target site in a mammal. A “target site” refers to a site in a mammal to which one desires to deliver a therapeutic formulation. For example, a target site can be any cell which is targeted by direct injection or delivery using antibodies (e.g., monospecific, chimeric or bispecific antibodies) liposomes, viral vectors or other delivery vehicles, including ribozymes. Examples of delivery vehicles include, but are not limited to, antibodies, artificial and natural lipid-containing delivery vehicles, viral vectors, and ribozymes. Natural lipid-containing delivery vehicles include cells and cellular membranes. Artificial lipid-containing delivery vehicles include liposomes and micelles. A delivery vehicle of the present invention can be modified to target to a particular site in a mammal, thereby targeting and making use of a nucleic acid molecule at that site. Suitable modifications include manipulating the chemical formula of the lipid portion of the delivery vehicle and/or introducing into the vehicle a compound capable ofspecifically targeting a delivery vehicle to a preferred site, for example, a preferred cell type. Specifically, targeting refers to causing a delivery vehicle to bind to a particular cell by the interaction of the compound in the vehicle to a molecule on the surface of the cell. Suitable targeting compounds include ligands capable of selectively (i.e., specifically) binding another molecule at a particular site. Examples of such ligands include Iiantibodies, antigens, receptors and receptor ligands. Manipulating the chemical formula of the lipid portion of the delivery vehicle can modulate the extracellular or intracellular targeting of the delivery vehicle. For example, a chemical can be added to the lipid formula of a liposome that alters the charge of the lipid bilayer of the liposome so that the liposome fuses with particular cells having particular charge characteristics. In one embodiment, an agent of the present invention is targeted to a γδ T cell by using an antibody that selectively binds to a protein expressed on the surface of the target γδ T cell. Preferably, the antibody binds to a γδ T cell receptor, with γδ T cell receptors comprising a Vγ4 chain being particularly preferred. Such an antibody can include functional antibody equivalents such as antibody fragments (e.g., Fab fragments or Fab2 fragments) and genetically-engineered antibodies, including single chain antibodies or chimeric antibodies, including bi-specific antibodies that can bind to mnore than one epitope. Such targeting antibodies are complexed with an agent that increases the action of the γδ T cell that is targeted, and serves to deliver the agent to the γδ T cell. The antibodies can be complexed to the target by any suitable means, including by complexing with a liposome, or by recombinant or chemical linkage of the agent to the antibody. In one embodiment, the agent is a second antibody or portion thereof that stimulates a γδ T cell and that forms a chimeric or bispecific antibody with the targeting antibody. The method of the present invention can be used in any animal, and particularly, in any animal of the Vertebrate class, Mammalia, including, without limitation, primates, rodents, livestock and domestic pets. Preferred mammals to treat using the method of the present invention include humans. Yet another embodiment of the present invention relates to a method to identify a compound that reduces or prevents airway hyperresponsiveness by increasing the action of γδ T cells. Such a method includes the steps of: (a) contacting a putative regulatory compound with a γδ T cell; (b) detecting whether the putative regulatory compound increases γδ T cell action; and, (c) administering the putative regulatory compound to a non-human animal in which airway hyperesponsiveness can be induced and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of the putative regulatory compound. Preferably, the γδ T cell is contacted with the regulatory compound under conditions wherein, in the absence of the putative regulatory compound, the action of the γδ T cell is not substantially increased (i.e., is at a resting, or baseline, level). A putative regulatory compound that increases γδ T cell action and that reduces or prevents airway hyperresponsiveness in the non-human animal is indicated to be a compound for reducing or preventing airway hyperresponsiveness. In this method, the step (b) of detecting can include, but is not limited to, a method selected from the group of measurement of measurement proliferation of said γδ T cell, measurement of cytokine production by said γδ T cell, measurement of calcium mobilization in said γδ T cell, measurement of cytokine receptor expression by said γδ T cell, measurement of CD69 upregulationby said γδ T cell, measurement of upregulation of CD44 by said γδ T cell, and measurement of cytoskeletal reorganization by said γδ T cell. Such methods are known in the art and are described above. In an alternate embodiment, such a method can include the steps of: (a) contacting a putative regulatory compound with an isolated γδ T cell and determining whether the putative regulatory compound binds to the γδ T cell (e.g., preferably to the γδ T cell receptor); an optional step (b) of further detecting whether compounds that bind to γδ T cell in (a) increase the action of γδ T cells in an assay for γδ T cell biological activity (e.g., a proliferation or cytokine assay); and (c) administering the putative regulatory compound to a non-human animal in which airway hyperresponsiveness can be induced and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of the putative regulatory compound. Yet another alternate embodiment of the method to identify a compound that reduces or prevents airway hyperresponsiveness associated with inflammation, includes the steps of: (a) contacting a cell or cell lysate which expresses a γδ T cell receptor with a putative regulatory compound; (b) detecting whether the putative regulatory compound stimulates a γδ T cell receptor function selected from the group of γδ T cell receptor expression, γδ T cell ligand binding or γδ T cell receptor biological activity (e.g., stimulation of proliferation, stimulation of cytokine production by a γδ T cell); and (c) administering the putative regulatory compound to a non-human animal in which airway hyperresponsiveness can be induced, and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of the putative regulatory compound. A putative regulatory compound that inhibits γδ T cell receptor expression, ligand binding or biological activity and that reduces or prevents airway hyperresponsiveness in the non-human animal is indicated to be a compound for reducing or preventing hyperresponsiveness associated with inflammation. In one alternate embodiment, step (a) of contacting comprises contacting the putative regulatory compound with a cell or cell lysate containing a reporter gene operatively associated with a regulatory element of the γδ T cell receptor, and step (b) of detecting comprises detecting increased expression of the reporter gene product. In another aspect of this embodiment, step (a) of contacting comprises contacting the putative regulatory compound with a cell or cell lysate containing transcripts of the γδ T cell receptor, and step (b) of detecting comprises detecting translational activation of the γδ T cell receptor transcript. As used herein, the term “putative” refers to compounds having an unknown or previously unappreciated regulatory activity in a particular process. As such, the term “identify” is intended to include all compounds, the usefulness of which as a regulatory compound of γδ T cell action for the purposes of reducing airway hyperresponsiveness is determined by a method of the present invention. The above described methods, in one aspect, involve contacting cells with the compound being tested for a sufficient time to allow for interaction of the putative regulatory compound with the γδ T cell and in one embodiment, with the γδ T cell receptor expressed by the cell. The period of contact with the compound being tested can be varied depending on the result being measured, and can be determined by one of skill in the art. For example, for binding assays, a shorter time of contact with the compound being tested is typically suitable, than then activation is assessed. As used herein, the term “contact period” refers to the time period during which cells are in contact with the compound being tested. The term “incubation period” refers to the entire time during which cells are allowed to grow prior to evaluation, and can be inclusive of the contact period. Thus, the incubation period includes all of the contact period and may include a further time period during which the compound being tested is not present but during which growth or cytokine production is continuing (in the case of a cell based assay) prior to scoring. The incubation time for growth of cells can vary but is sufficient to allow for the binding of the γδ T cell receptor and/or increased action of the γδ T cell. It will be recognized that shorter incubation times are preferable because compounds can be more rapidly screened. A preferred incubation time is between about 1 minute to about 72 hours. The above-described methods for identifying a compound of the present invention include contacting a γδ T cell or a γδ T cell lysate with a compound being tested for its ability to bind to and/or regulate the action of the γδ T cell or its receptor, respectively. The conditions under which the cell or cell lysate of the present invention is contacted with a putative regulatory compound, such as by mixing, are any suitable culture or assay conditions and includes an effective medium in which the cell can be cultured or in which the cell lysate can be evaluated in the presence and absence of a putative regulatory compound. For example, γδ T cells or other suitable cells expressing a γδ T cell receptor (i.e., the test cells) can be grown in liquid culture medium or grown on solid medium in which the liquid medium or the solid medium contains the compound to be tested. In addition, as described above, the liquid or solid medium contains components necessary for cell growth, such as assimilable carbon, nitrogen and micro-nutrients. Cells of the present invention can be cultured in a variety of containers including, but not limited to, tissue culture flasks, test tubes, microtiter dishes, and petri plates. Culturing is carried out at a temperature, pH and carbon dioxide content appropriate for the cell. Such culturing conditions are also within the skill in the art. Cells are contacted with a putative regulatory compound under conditions which take into account the number of cells per container contacted, the concentration of putative regulatory compound(s) administered to a cell, the incubation time of the putative regulatory compound with the cell, and the concentration of compound administered to a cell. Determination of effective protocols can be accomplished by those skilled in the art based on variables such as the size of the container, the volume of liquid in the container, conditions known to be suitable for the culture of γδ T cells, and the chemical composition of the putative regulatory compound (i.e., size, charge etc.) being tested. A preferred amount of putative regulatory compound(s) comprises between about 1 nM to about 10 mM of putative regulatory compound(s) per well of a 96-well plate. Suitable cells for use with the present invention include any γδ T cell and in assays which only require the expression of a γδ T cell receptor, any cell that has been transfected with and expresses a γδ T cell receptor. γδ T cells can include normal γδ T cells (i.e., native, or natural isolates), T cell clones (i.e., a natural isolate that has been clonally selected and expanded), or γδ T cell hybridomas (i.e., natural isolates that have been fused with a myeloma cell line to produce an immortalized T cell hybrid). In one embodiment, host cells genetically engineered to express a functional γδ T cell receptor that responds to activation by known stimulators of γδ T cells can be used as an endpoint in the assay; e.g., as measured by a chemical, physiological, biological, or phenotypic change, induction of a host cell gene or a reporter gene, change in cAMP levels, activity of other intracellular signal transduction molecules, proliferation, differentiation, etc. Cytokine-producing cells for use with the present invention include mammalian, invertebrate, plant, insect, fungal, yeast and bacterial cells. Preferred cells include mammalian, amphibian and yeast cells. Preferred mammalian cells include primate, non-human primate, mouse and rat. In one embodiment, the test cell (host cell) should express a functional γδ T cell receptor that gives a significant response to stimulation through the γδ T cell receptor, preferably greater than 2, 5, or 10-fold induction over background. As disclosed above, the present methods also make use of non-cell based assay systems to identify compounds that can regulate AHR. For example, isolated membranes may be used to identify compounds that interact with the γδ T cell receptor being tested. Membranes can be harvested from cells expressing γδ T cell receptors by standard techniques and used in an in vitro binding assay. A 125I-labeled γδ T cell receptor ligand is bound to the membranes and assayed for specific activity; specific binding is determined by comparison with binding assays performed in the presence of excess unlabeled ligand. Membranes are typically incubated with labeled ligand in the presence or absence of test compound. Compounds that bind to the receptor and compete with labeled ligand for binding to the membranes reduced the signal compared to the vehicle controlsamples. Alternatively, soluble γδ T cell receptors may be recombinantly expressed and utilized in non-cell based assays to identify compounds that bind to γδ T cell receptors. Recombinantly expressed γδ T cell receptor polypeptides or fusion proteins containing one or more extracellular domains of a γδ T cell receptor can be used in the non-cell based screening assays. Alternatively, peptides corresponding to one or more of the cytoplasmic domains of the γδ T cell receptor or fusion proteins containing one or more of the cytoplasmic domains of the γδ T cell receptor can be used in non-cell based assay systems to identify compounds that bind to the cytoplasmic portion of the γδ T cell receptor; such compounds may be useful to modulate the signal transduction pathway of the γδ T cell receptor. In non-cell based assays the recombinantly expressed yoT cell receptor is attached to a solid substrate such as a test tube, microtitre well or a column, by means well known to those in the art. The test compounds are then assayed for their ability to bind to the γδ T cell receptor. As discussed above, in vitro cell based assays may be designed to screen for compounds that regulate γδ T cell receptor expression at either the transcriptional or translational level. In one embodiment, DNA encoding a reporter molecule can be linked to a regulatory element of a γδ T cell receptor gene and used in appropriate intact cells, cell extracts or lysates to identify compounds that modulate γδ T cell receptor gene expression, respectively. Appropriate cells or cell extracts are prepared from any cell type that normally expresses a γδ T cell receptor gene, thereby ensuring that the cell extracts contain the transcription factors required for in vitro or in vivo transcription. The screen can be used to identify compounds that modulate the expression of the reporter construct. In such screens, the level of reporter gene expression is determined in the presence of the test compound and compared to the level of expression in the absence of the test compound. To identify compounds that regulate γδ T cell receptor translation, cells or in vitro cell lysates containing γδ T cell receptor transcripts may be tested for modulation of γδ T cell receptor mRNA translation. To assay for inhibitors of translation, test compounds are assayed for their ability to modulate the translation of γδ T cell receptor mRNA in in vitro translation extracts. Compounds that increase the level of γδ T cell receptor expression, either at the transcriptional or translational level, may be useful for reduction of AHR. Finally, a putative regulatory compound of the present invention can be evaluated by administering putative regulatory compounds to a non-human test animal (and eventually, to a human test subject) and detecting whether the putative regulatory compound reduces AHR in the test animal. Animal models of disease are invaluable to provide evidence to support a hypothesis or justify human experiments. For example, mice have many proteins which share greater than 90% homology with corresponding human proteins. Preferred modes of administration, including dose, route and other aspects of the method are as previously described herein for the therapeutic methods of the present invention. The test animal can be any suitable non-human animal, including any test animal described in the art for evaluation of AHR. The test animal can be, for example, an established mouse model of AHR, as previously described (see, for example, Takeda et al., (1997). J. Exp. Med. 186, 449-454; Renz et al., 1992, J. Allergy Clin. Immunol. 89:1127-1138; Larsen et al., 1992, J. Clin. Invest. 89:747-752; and Saloga et al., 1993, J. Clin. Itivest. 91:133-141). This non-human model system is an accepted model of airway hyperresponsiveness associated with allergic inflammation which shares many characteristics with human respiratory conditions associated with allergic inflammation, including airway hyperresponsiveness, airway fibrosis, increased IgE production, and eosinophilia. More specifically, the mouse model is an antigen-driven minrine system that is characterized by an immune (IgE) response, a dependence on a Th2-type response, and an eosinophil response, and is a valid model for studying allergic inflammation of the airways in mammals, and particularly in humans. The model is characterized by both a marked and evolving hyperresponsiveness of the airways. Briefly, as an exemplary protocol for this murine model, mice (typically BALB/c) are immunized intraperitoneally with ovalbumin (OVA). The mice are then chronically exposed (i.e., challenged) for 8 days (i.e., 8 exposures of 30 minutes each in 8 days) to aerosolized OVA. It should be noted that both immunization and subsequent antigen challenge are required to observe a response in mice. To characterize the murine model, pulmonary function measurements of airway resistance (RL) and dynamic compliance (CL) and hyperresponsiveness are obtained as described in Example 1 below. Compounds identified by any of the above-described methods can be used in a method for the reduction or prevention of AHR as described herein. The following examples are provided for the purposes of illustration and are not intended to limit the scope of the present invention. EXAMPLES Example 1 The following example demonstrates that airway reactivity is increased in the absence of γδ T cells. The following materials and methods are used throughout the examples herein, as indicated. Animals. The influence of γδ and αβ cells on airway hyperresponsiveness (AHR) was assessed in a murine model of allergen-induced, T cell-dependent asthma. For these experiments, BALB/c mice, C57BL/6 mice, TCR-β−/− mice (mice deficient in αβ T cells and back-crossed onto C57BL/6 genetic background), and TCR-δ−/− mice (mice deficient in γδ T cells and back-crossed onto C57BL/6 genetic background) were purchased from The Jackson Laboratory (Bar Harbor, Me.), and cared for at National Jewish Medical and Research Center (Denver, Colo.) following guidelines for immunodeficient animals. Sensitization and airway challenge. Mice (BALB/c, C5713L/6, TCR-β−/− and TCR-δ−/−) were treated with hamster Ig (sham depletion) or with monoclonal antibody against TCR-8 or TCR-β and received one of the following treatments: (1) no ovalbumin (OVA) treatment (denoted “NT”); (2) airway exposure to nebulized OVA (1% in saline) alone, using ultrasonic nebulization (particle-size 3-5 μm2) for 20 minutes on three consecutive days (denoted “3N”); or (3) sensitization to OVA by intraperitoneal injection of 20 μg of OVA (Grade V; Sigma) emulsified in 2.25 mg alum (Alumimuject®; Pierce, Rockford, Ill.) in a total volume of 100 μl on days 0 and 14, followed by aerosolized airway challenge with nebulized OVA on days 28, 29 and 30 (denoted “2ip3N”). Determination of airway responsiveness and inflammation was assessed 48 hours after the last nebulized OVA exposure for 3N- and 2ip3N-treated mice. For each of these treatments and type of mice, groups of four mice were analyzed in each independent experiment. Determination ofairway responsiveness. Airway responsiveness was assessed as a change in airway function after challenge with aerosolized methacholine (MCh) through the airways. Anesthetized and tracheostomized mice were mechanically ventilated, and lung function was assessed as a modification to known procedures. Briefly, a four-way connector was attached to the tracheotomy tube (stainless steel cannula, 18-gauge, with two ports connected to the inspiratory and expiratory sides of two ventilators). Ventilation was achieved at 160 breaths per minute and a tidal volume of 0.15 ml with a positive end-expiratory pressure of 2-4 cm H2O (model 683; Harvard apparatus, South Natwick, Mass.). Aerosolized MCh was administered for 10 breaths at rate of 60 breaths/min in increasing concentrations (1.56, 3.125, 6.25 and 12.5 mg/ml MCh for BALB/c mice, 6.25, 12.5, 25, 50 and 100 mg/ml MCh for C57BL/6 mice) with a tidal volume of 0.5 ml by the second ventilator (model SN-480-7-3-2T; Shineno Manufacturing, Tokyo, Japan). The chamber containing the mouse was continuous with a 1.0-liter glass bottle filled with copper gauze to stabilize the volume signal for thermal drift. Transpulmonary pressure was detected by a pressure transducer with one side connected to the fourth port of a four-way connector and the other side connected to a second port on the plethysmograph. Changes in lung volume were measured by detecting pressure changes in the plethysmographic chamber through a port in the connecting tube with a pressure transducer and then referenced to a second copper-gauze filled 1.0-liter glass bottle. Flow was measured by digital differentiation of the volume signal. Lung resistance (RL) and dynamic compliance (C) were continuously computed (Labview; National Instruments, Austin, Tex.) by fitting flow, volume and pressure to an equation of motion. After each aerosol MCh challenge, the data were continuously collected for 1-5 min. and maximum values of RL, and minimum values of C were used to express changes in murine airway function. Depletion with monoclonal antibody against TCR. Depletion was achieved by injection into the tall vein of 200 μg hamster monoclonal antibodies against TCR-δ (mixture of GL3 (PharMingen) and 403.A10) or TCR-β (H57-597 (PharMingen)). Sham depletion was accomplished with hamster Ig (Jackson Laboratories, Bar harbor, Me.). Broncho alveolar lavage (BAL) fluid. Immediately after assessment of AHR, lungs were lavaged through the tracheal tube with Hank's balanced solution (HB55 1×1 ml using 1 lavage injection with 1 ml of HBSS at 37° C.). The volume of and number of cells in the BAL fluid were assessed (Coillter Counter; Coulter, Hialeah, Fla.). BAL fluid cells were stained with Leukostate (Fischer Diagnostics, Pittsburgh, Pa.) on cytosine slides and differentiated by experimenters “blinded” to sample identity counting at least 200 cells with a light microscope. Histologic examination. Lungs were inflated through the tracheas and fixed with 10% formaldehyde. The left lung was excised and embedded in paraffin, and tissue sections 5 μm in thickness were affixed to slides and deparaffinized. Sections were stained with hematoxlin and eosin and the inflammatory reaction assessed by light microscopy. Eosinophils and major basic protein staining. A FITC-conjugated rabbit monoclonal antibody against mouse major basic protein was used to assess eosinophil numbers by immunohistochemistry. Positive events were counted in the submucosatissue around central airways using the IPLab2 software (Signal Analytics, Vienna, Va.) counting four different sections per animal. Statistical analysis. All results are expressed as the mean and standard deviation (s.d.) except where otherwise indicated. Analysis of variance was used to determine the levels of difference between all groups. Pairs of groups were compared by unpaired two-tailed Student's t-test. P values were considered significant at 0.05. Results. As previously shown by studies that established the role of αβ T cells in the development of AHR (Hamelmann et al., 1996, J. Exp. Med. 183:1719-1729; Takeda et al., 1997, J. Exp. Med. 186:449-454), C57BL/6 mice that were systemically sensitized to ovalbumin (OVA) and challenged through the airways developed AHR to inhaled methacholine (MCh), whereas untreated mice or those exposed to OVA only through the airways did not (FIG. 1A). FIG. 1A shows the RL changes in normal CS7BL/6 mice after 2ip3N treatment (▪), 3N treatment (□) and untreated (⋄). There were no differences in baseline responses to saline in any of these groups. R baseline values (in cm H2O/ml per second) were 0.56±0.04 (2ip3N), 0.57±0.03 (3N) and 0.53±0.03 (NT) P(0.05, 2ip3N compared with 3N). Mice genetically deficient to γδ T cells (T-cell receptor (TCR)-δ−/−) also developed AHR, in contrast to mice deficient in αβ T cells (TCR-β−/−) (FIG. 1B). FIG. 1B shows RL changes in TCR-δ−/− (●), TCR-β−/− (▴) and normal C57BL/6 (▪) mice after 2ip3N treatment inset. There were no significant differences indicated in baseline responses to saline (data not shown). However, in contrast to a report emphasizing the enhancement of allergic airway inflammation by γδ T cells on AHR (Zuany-Amorim et al., 1998, Science 280:1265-1267), the present inventors detected increased responsiveness to MCh in the absence of γδ T cells, indicating a suppressive effect of γδ T cells on AHR in this model. Since both TCR-β−/− And TCR-δ−/− mice had baseline values in airway responsiveness similar to those of the genetically normal control mice (data not shown), background airway tone variations could be ruled out as an explanation of these differences. The broncho alveolar lavage (BAL) fluid and lung sections of C57BL/6 and TCR-β−/− mice challenged systemically and through the airways had similar inflammatory infiltrates with increased eosinophil numbers, whereas TCR-β−/− mice lacked such inflammatory infiltrates (FIG. 1D). FIG. 1D shows the BAL fluid cell composition for total cells, eosinophil and macrophages in 2ip3N-treated C57BL/6, TCR-δ−/− and TCR-β−/− mice. Each bar represents data from at least three independent experiments using 9-12 mice (P<0.05; brackets indicate cell counts being compared; histology not shown). Consistent with previous findings, TCR-β−/− mice had lower numbers of eosinophils in the BAL fluid as well as fewer eosinophils in lung tissue sections, indicating that γδ T cells also influence the influx of eosinophils to the inflammatory sites. To exclude the possibility of developmental compensatory mechanisms in the genetically TCR-deficient mice, γδ T cells were also depleted in TCR-sufficient mice (i.e., wild type mice) by injecting these mice with monoclonal antibodies against TCR-δ. The results were similar to those in TCR-δ−\− mice, in that AHR was increased in mice depleted of γδ T cells. Moreover, no differences after treatment with monoclonal antibodies against TCR-δ were found in the responses between C57BL/6 and BALB/c mice, two strains known to differ in their airway responsiveness after OVA sensitization and challenge (FIG. 1C). FIG. 1C shows RL changes in TCR-δ-depleted (▾) or sham-depleted (∇) BALB/c mice after 2ip3N treatment. There were no significant differences in baseline responses to saline in any of these groups. RL baseline values (in cm H2O/ml per second) were 0.60±0.03 (sham-depleted) and 0.59±0.02 (TCR-6-depleted). Each curve represents data from at least three independent experiments using 9-12 mice (P<0.05). Thus, theregulatory effects of γδ T cells in OVA-induced AHR seem to be independent of these genetic differences. The cellular composition in BAL fluid and lung tissue of the antibody-depleted mice was also similar to that found in the genetically deficient mice (data not shown). Based on these findings, it was concluded that, during allergic ax T cell-dependent AHR, γδ T-cell deficiency results in increased airway responsiveness, despite a concurrent reduction in eosinophilic inflammation. Example 2 The following example demonstrates that the effect of γδ T cells on airway hyperresponsiveness does not require systemic sensitization. Since γδ T-cell deficiency was shown to influence AHR in allergen-sensitized and challenged mice (Example 1), it was next determined whether systemic sensitization with antigen was necessary for these effects to be shown. In this experiment, the effect γδ T cells on mice sensitize only through the airways was investigated, using the protocol described above (3N treatment). Results are shown in FIGS. 2A-21. FIGS. 2A, 2C and 2G illustrate changes in airway resistance (RL); FIGS. 2B, 2D and 2F illustrate changes in dynamic compliance (C). FIGS. 2A and 2B show the effects of 3N treatment in C57BL/6 (□), TCR-δ−/− (●) and TCR-β−/− (Δ) mice. FIGS. 2C and 2D show the effects of 3N treatment in sham-depleted (□) and γδ T cell-depleted (▪) C57BL/6 mice. FIGS. 2E and 2F show the effects of 3N treatment in sham-depleted (⋄) and γδ T cell-depleted (♦) BALB/c mice. There were no significant differences in responses to saline in any of these groups. RL baseline values in cm-H2O/ml per second) were 0.59±0.08 (TCR-δ−/−); 0.57±0.03 (C57BL/6); 0.59±0.07 (TCR−/−); 0.57±0.03 (sham-depleted C57BL/6); 0.62±0.08 (TCR-8-depleted C57BL/6); 0.54±0.04 (sham-depleted BALB/c); 0.56±0.04 (TCR-δ-depleted BALB/c). Each curve represents data from at least three independent experiments using 9-12 mice (P<0.05). FIG. 2G shows the BAL fluid cell composition for total cells (TC), eosinophil (EOS) and macrophages (Mac) in 3N-tested mice; C57BL/6, TCR-δ−/−, TCR-β−/− mice. FIG. 2H shows the BAL fluid cell composition of these cells in sham-depleted and γδ T cell-depleted C57BL/6 mice. FIG. 2I shows the BAL fluid cell composition for these cells in BALB/c mice. Each bar represents data from at least three independent experiments using 9-12 mice (P<0.05). The results in FIGS. 2A-21 demonstrated that TCR-δ−/− mice had a higher level of to airway responsiveness than C57BL/6 mice, even when they were exposed to OVA only through the airways (nebulized OVA on 3 consecutive days; 3N treatment). The higher increases in airway responsiveness in TCR-δ−/− mice involved both the larger airways as assessed by airway resistance (RL) (FIG. 2A) and the smaller airways, as demonstrated by changes in dynamic lung compliance (FIG. 2B). As expected, no AER was detectable in TCR-67 −/− mice. In mice treated with antibodies to deplete γδ T cells changes in airway function again resembled those of the genetically deficient mice (FIGS. 2C-F). However, despite these obvious changes in airway function, mice deficient in γδ T cells did not demonstrate increases when compared to TCR-sufficient control in inflammatory infiltrates in the BAL fluid or the lung tissue (FIGS. 2G-2I; histology not shown). Thus, in the absence of systemic antigen sensitization and the associated inflammatory response, γδ T cell deficiency was still associated with increased airway responsiveness, indicating a mechanism independent of antigen-specific reactivity, and thus perhaps of αβ T-cell responses. Example 3 The following example demonstrates that γδ T-cell regulation of AHR is independent of αβ T cells. To further elucidate the mechanism of the observed increase in AHR corresponding to γδ deficiency, the effect of γδ T-cell depletion on airway responsiveness in 3N-treated mice (see Example 1) was assessed in mice genetically deficient in αβ T cells, by injecting TCR-β−/− mice with antibodies agai-β−/− TCR-8 as described in Example 1, followed by evaluation of AHR as described in Example 1. The results of this experiment are shown in FIGS. 3A and 3B (sham-depleted (◯) and γδ T cell-depleted (⊙) CR-β−/− mice). The reciprocal condition of αβ T-cell depletion in mice genetically deficient in γδ T cells was also assessed using an antibody against TCR-p in TCR-δ−/− mice, results shown in FIGS. 3C and 3D (sham-depleted (LI) and αβ T cell-depleted (E) TCR-β−/− mice). As a further control, T cell-deficient mice were treated with antibodies specific for the type of T cells they were lacking (non-relevant treatments). Changes in airway resistance (RL) are shown in FIGS. 3A and 3C; changes in dynamic compliance (Cdy.) are shown in FIGS. 3B and 3D. There were no significant differences in baseline responses to saline in any of these groups in FIGS. 3A-3D). RL baseline values (in cm H2O/ml per second) were 0.59±0.08 (sham-depleted TCR-β−/−); 0.58±0.03 (TCR.8-depleted TCR-β−/−); 0.59±0.07 (sham-depleted TCR-δ−/−); 0.57±0.02 (TCR-3-depleted TCR-δ−/−). Sham-depleted mice did not react to nebulized saline exposure alone (open triangles, FIGS. 3A and 3B; open diamonds, FIGS. 3C and 3D). Each curve represents data from at least three independent experiments using 9-12 mice (P<0.05). FIGS. 3E and 3F illustrate BAL fluid cell composition for total cells (TC) eosinophil (EOS) and macrophages (Mac) in 3N-treated mice; sham-depleted and γδ T cell-depleted TCR-β−/− mice (FIG. 3E); and in sham-depleted and αβ T cell-depleted TCR-δ−/− mice (FIG. 3F). Each bar represents data from at least three independent experiments using 9-12 mice. FIGS. 3A-3D demonstrate that only the depletion of γδ T cells in TCR-β−\− mice resulted in increases in AHR. Depletion of αβ T cells in TCR-δ−/− mice caused a small decrease in AHR. The non-relevant treatments did not produce substantial effects (not shown). Again, BAL fluid (FIGS. 3E and 3F) and lung tissue (not shown) had no inflammatory infiltrates with eosinophil in any of these mice. Example 4 The following example demonstrates that γδ T-cell regulation is independent of B-cell and cytokine responses. Since ovalbumin (OVA)-specific immunoglobulin (Ig) production or T-helper 2 (Th2) associated cytokines have been implicated in the development of AHR, serum OVA-specific immunoglobulin production (including IgG1, IgG2a, and IgE) as well as interleukin (IL)-4, IL-5 and gamma interferon (IFN γ) levels were measured in the BAL fluid of C57B.L/6, TCR-β−/− and TCR-δ−/− mice after 3N (See Example 1: airway exposure to nebulized OVA alone) or 2ip3N treatment (See Example 1: systemic sensitization to OVA). Measurement ofaantibody against OVA. Serum levels of OVA-specific IgG1, IgG2a, and IgE were measured by ELISA. Briefly, serum samples were added to Immulon 2 plates (Dynatech, Chantilly, Virginia) coated with 5 μg/ml OVA. OVA-specific IgE was detected with biotinylated antibody against IgE (PharMingen, San Diego, Calif.) and amplified by an avidiniorseradish-peroxidate (Sigma). OVA-specific IgG1 and IgG2 were detected with alkaline phosphatase labeled antibodies (PharMingen, San Diego, Calif.). OVA-specific antibody titers of samples were related to an internal “pooled” standard arbitrarily assigned to be 100 ELISA units (EU). FIGS. 4A-4C show individual levels of OVA-specific IgG1, (FIG. 4A), IgE (FIG. 4B) and IgG2a (FIG. 4C), as defined by ELISA units to an OVA standard, for mice (horizontal axis, mouse strain, n=7-12) left untreated (◯) or given 3N(●) or 2ip3N (▪) treatment. Crosses represent the means of the immunoglobulin levels (horizontal axis, mean±s.e.m.; P<0.05) between levels of immunoglobulin of 3N and 2ip3N-treated mice. As shown in FIGS. 4A-4C, after 3N treatment, no significant OVA-specific Ig levels were detected in any of the mice, including TCR-δ−/− mice, despite the fact that the TCR-δ−/− mice showed increased airway responsiveness after this treatment. As expected, after 2ip3N treatment, αβ T cell-sufficient mice showed increased levels of OVA-specific Ig production whereas αβ T cell-deficient mice did not. OVA-specific IgG may be an exception to this observation, because some of the TCR-β−\− mice showed increased levels after 2ip3N treatment (FIG. 4C). Cytokine levels in BALfluid. The levels of IFN-γ, IL-4 and IL-5 in BAL fluid were assessed by ELISA. Briefly, samples were added to Immulon 2 plates (Dynatech, Chantilly, Va.) coated with monoclonal antibodies against IFN-γ (clone R4-6A2), IL-4 (clone 11B11) or IL-5 (clone TRFK-5) (all from PharMingen, San Diego, Calif.). Biotinylated monoclonal antibodies against IFN-γ (clone XMG 1.2), IL-4 (clone BVD6-24G2) or IL-5 (clone TRFK-4) (all from PharMingen, San Diego, Calif.) were used for amplified detection. Cytokine levels were calculated by comparison with known cytokine standards with a detection limit of 4 pg/ml for each cytokine. FIGS. 5A-5C show the concentration (pg/ml) of IL-5 (FIG. 5A), IL-4(FIG. 5B) and IFN-γ (FIG. 5C) in BAL fluid of mice (horizontal axis, strains; n=7-12 mice per treatment) after receiving no treatment (□), 3N (▪) treatment, or 2ip3N (▪) treatment (error bars: s.e.m.). There were no statistical differences between 3N-treated and 2ip3N-treated mice. None of the cytokines assessed in the BAL fluid were increased in TCR-δ−/− mice after 3N treatment (FIGS. 5A-5C), despite increased airway responsiveness after this treatment. The same cytokines were increased after 2ip3N treatment in the αβ T cell-sufficient mice, but not in TCR-β−/− mice. However, TCR-β−/− mice had increased baseline levels for all of the tested cytokines, despite their lack of airway responsiveness after either 3N or 2ip3N treatments. The results described here demonstrate a previously unknown γδ T cell-dependent mechanism in the regulation of airway responsiveness, which is independent of αβ T cells and their allergen-specific responses. This experiment shows no evidence to indicate that antibodies are involved in this regulatory mechanism. Furthermore, the increased airway responsiveness in TCR-δ−/− mice was not correlated with increases in cytokine levels previously suggested to be involved in models allergic inflammation (McMenamin et al., 1994, Science 265:186-1871; Zuany-Amorim et al., 1998, supra). These results differ from earlier reports, which have emphasized the role of γδ T cells in regulating allergic αβ T-cell and allergen specific B-cell responses, or their role in promoting allergen-induced eosinophilia and IgE responses (McMenamin et al., 1994, supra; Zuany-Amorim et al., 1998, supra; Schramm et al., 1999, International Conference of the American Thoracic Society; vol. 159:A255 (American Journal of Respiratory and Critical Care Medicine, San Diego, Calif.)). The mechanism of γδ T cell-dependent regulation of airway responses described herein is therefore not restricted to allergic inflammation. Example 5 The following example demonstrates that, in addition to being independent of αβ T cells, the γδ T cell-dependent regulatory effects on airway responsiveness described herein are not connected to γδ T cell-dependent eosinophilia, further emphasizing the differences from previously reported γδ T cell-dependent mechanisms. In addition to the independence of αβ T cells, the γδ T cell-dependent regulatory effects on airway responsiveness described herein are in contrast to γδ T cell-dependent eosinophilia, further emphasizing the differences from previously reported γδ T cell-dependent mechanisms (McMenamin et al., 1994, supra; Zuany-Amorim et al., 1998, supra). To compare the results described herein with earlier studies, the more extensive systemic sensitization protocol of previous studies, involving seven intraperitoneal inj ections of OVA over 14 days, was evaluated. Using these conditions, differences in AHR between wild-type and γδ T cell-deficient mice were no longer observed, in agreement with the earlier studies (data not shown). The previous findings of γδ T cell-dependent lung eosinophilic infiltrates was also confirmed (data not shown). Thus, extensive systemic sensitization seems to promote immune-dependent facets of γδ T-cell functions, including γδ T cell-dependent eosinophilia. Whether or not γδ T cells arem actually capable of recognizing OVA remains undetermined. The present findings in the TCR-β−\− mice sensitized and challenged with OVA do not specifically address allergen-specific activation of γδ T cells in the development of AHR or eosinophilic inflammation. In TCR-γδ−/− mice depleted with monoclonal antibody against TCR-β and exposed to airway aerosolized OVA alone, airway responsiveness was slightly diminished (FIGS. 3C and 3D). Therefore, it remains possible that three exposures to aerosolized OVA alone activate αβ T cells, especially when the negative regulation by γδ T cells is absent. Because the regulatory effects on AHR in the conditions of the present study were associated with a reduction in eosinophil infiltration, eosinophil-independent mechanisms must be considered, although eosinophil activation itself was not monitored. The cell entities that γδ T cells could influence include alveolar macrophages, airway epithelial cells and airway smooth muscle cells. γδ T cells have already been implicated in regulatory effects involving alveolar macrophages in tuberculosis. γδ T cells can alter the development of alveolar macrophage populations, as untreated TCR-δ−/− mice have lower macrophage cell counts in BAL fluid than their T cell-sufficient control counterparts (data not shown). This action could relate to the finding that TCR-δ−/− mice are deficient in monocyte chemoattractant protein 1 (DiTirro et al., 1998, Infec. Immun. 66:2284-2289). Airway epithelial cells are another source of reactive mediators leading to AHR (King et al., 1999, J. Imunol. 162:5033-5036). The intraepithelial/submucosa localization of γδ T cells facilitates their reaction to epithelial cell changes. As do other intraepithelial γδ T cells, lung γδ T cells may provide mediators for epithelial repair processes and other epithelial responses elicited by AHR-inducing stimuli. Furthermore, intraepithelial/submucosa ybT cells could exert their regulatory effects directly on airway smooth muscle cells, for example, by modifying secretin of smooth muscle cell derived cytokines, such as GM-CSF, IL-5 and IL-4. In summary, these data demonstrate a previously unknown, αβ T cell-independent and probably also B cell-independent mechanism of airway regulation by γδ T cells. This mechanism may co-exist with immunoregulatory effects of γδ T cells on αβ T cell-dependent pathways of AHR. Example 6 The following example demonstrates that airway hyperresponsiveness is increased in the absence of tumor necrosis factor-α (TNF-α), and that γδ T cells play a role in the failure of TNF-α transgenic mice to develop airway hyperresponsiveness. Airway Hyperresponsiveness is Increased in the Absence of TNF-α First, airway responsiveness to inhaled Mch was assessed in TNF-α deficient mice. Female C57BL/6 mice from 8 to 10 weeks of age were purchased from the Jackson Laboratories (Bar Harbor, Me.). Mice genetically deficient for TNF-α were a gift from Dr. John Harty, University of Iowa, Iowa City, Iowa. These mice were originally derived from intercrosses of (129Sv×C57BL/6)F1 mice heterozygous for the mutated 129/Sv TNF-a gene and maintained as a line of mixed 129/B6 genetic background homozygous for the mutation since 1996. The mice were maintained on OVA-free diets. All experimental animals used in this study were under a protocol approved by the Institutional Animal Care and Use Committee of the National Jewish Medical and Research Center. Both OVA-sensitized and non-sensitized TNF-α deficient mice were challenged with an aerosol of OVA on three consecutive days, in parallel with C57BL/6 controls. Briefly, each strain of mouse was grouped based on the following treatments (4 mice/group/experiment): (a) airway challenge (×3) with OVA nebulization alone (N group); or (b) intraperitoneal sensitization with OVA and OVA airway challenge (IPN group). Mice were sensitized by intraperitoneal injection of 20 μg of OVA (Grade V; Sigma) emulsified in 2.25 mg alum (AlumImuject; Pierce, Rockford, Ill.) in a total volume of 100 μl on days 0 and 14. Mice were challenged via the airways to OVA (1% in saline) for 20 min. on days 28, 29 and 30 by ultrasonic nebulization (De Vilbiss, particle size 1-5 μm). Lung resistance (RL) and dynamic compliance (Cdyn) were assessed 48 hrs after the last allergen challenge, and the mice were sacrificed to obtain tissues and cells for further assays. Airway resistance and Cdyn were determined as described above in Example 1. Following OVA sensitization and challenge, C57BL/6 mice developed significant increases in RL and decreases in Cdyn in a dose-dependent manner, compared to mice only challenged with OVA (data not shown). Mice genetically deficient in TNF-α developed AHR and to a greater extent than the C57BL/6 animals. In non-sensitized mice receiving airway challenge alone, the degree of responsiveness was only slightly higher in the TNF-α deficient mice. The number and types of inflammatory cells in the airways of TNF-α sufficient and deficient mice were measured in bronchoalveolar lavage fluid (BALF) (data not shown). Briefly, after assessment of RL and Cdyn, lungs were lavaged via the tracheal tube with Hank's balanced salt solution, (HBSS, 1×1 ml, 37° C.). The volume of collected BALF was measured in each sample and the number of BALF cells was counted by cell counter (Coulter Counter; Coulter Co., Hialeah, Fla.). Cytospin slides were stained with Leukostat (Fisher Diagnostics, Pittsburgh, Pa.) and differentiated in a blinded fashion by counting at least 300 cells under light microscopy. Cytokine levels (IL-4, IL-5, IL-10, and IFN-γ) in BALF supernatants were measured by ELISA as described in Example 4 above. Cytokine levels were determined by comparison with the known standards. The limits of detection were 4 pg/ml. In C57BL/6 mice, sensitization and challenge to OVA resulted in a marked increase in inflammatory cell numbers compared with challenge alone. TNF-α deficient mice showed a similar inflammatory cell response, but the numbers of eosinophils in BALF were significantly lower than in C57BL/6 mice (data not shown). Inflammatory cells were also measured in the peribronchial and perivascular tissue. Briefly, lung cells were isolated as previously described (28) and passed through nylon wool columns to yield an enriched T cell preparation containing >90% CD3+cells. For cytofluorographic analysis, mAbs were conjugated with N-hydroxysuccinimido-biotin (Sigma) and/or fluorescein isothiocyanate isomer I on Celite (Sigma). Then, 1-2×106 cells in 96-well plates (Falcon-Becton Dickinson, Franklin Lakes, N.J.) were stained by using one- or two-color techniques and analyzed cytofluorographically on XL2 (Coulter, Miami, Fla.) counting 150,000 events per gated region. For each of the gated populations, mean fluorescence intensity (MFI) was examined to assess shifts in fluorescence of the examined populations. Streptavidin-phycoerythrin (diluted at 1:100 per 1×106 cells, Tago Immunologicals Biosource, Camarillo, Calif.) was used for the biotin-conjugated antibodies to enhance detection. In mice challenged only, very little inflammatory cell infiltration was detected whereas intraperitoneal sensitization and subsequent challenge with OVA via the airways increased the number of eosinophils and lymphocytes at these sites. Inflammatory cell infiltration in sensitized/challenged TNF-α deficient mice was similar to that in sensitized and challenged C57BL/6 animals (data not shown). γδ T Cells in SP-C-TNF-α Transgenic Mice. For the following experiments, mice expressing the TNF-a gene under the control of the surfactant SP-C promotor (SP-C-TNF-α transgenic mice) were a gift from Dr. Yoshitaka Miyazaki, Department of Clinical Immunology, Medical Institute of Bioregulation, Kyushu University, Beppu, Japan. The transgenic founder mice (C57BL/6×DBA/2 F1) were backcrossed with C57BL/6 mice to generate F1 hybrid transgenic mice and maintained as a heterozygous line by repeated backcrossing since 1995. All transgenic mice were identified by PCR analysis of genomic DNA. Littermate transgene-negative mice were used as controls. An increased frequency of γδ T cells has been demonstrated in the SP-C-TNF-α transgenic mice (Nakama et al., Exp. Lung Res., 24:57-70, 1998). The present inventors therefore investigated the effects of TCR-δ mAb on the γδ T cell populations in the lung in OVA sensitized and challenged TNF-α deficient and transgenic mice. Briefly, depletion was achieved following injection of 200 μg hamster IgG mAb anti-TCR-8 (1:1 mixture of GL3 and 403A10) into the tail vein 3 days prior to the first OVA challenge. Sham-depletion was carried out using hamster IgG (Jackson Laboratories, Bar Harbor, Me.). OVA sensitization and challenge was carried out as described above. γδ T cells in the lung were analyzed by flow cytometric analysis. The number of γδ T cells in the lung in TNF-α deficient mice was significantly lower than in normal C57BL/6 mice (data not shown). In contrast, the number of γδ T cells in the transgenic mice was significantly increased compared to littermate transgene-negative mice. Injection of TCR-δ mAb significantly suppressed the numbers of γδ T cells in the lung in sensitized and challenged transgenic mice as well as in C57BL/6 and littermate transgene-negative mice; the lower numbers in the TNF-α deficient mice did not change significantly (data not shown). Airway Responsiveness in TNF-α Transgenic Mice Following γδ T cell Depletion. As described in Examples 1-6, the present inventors demonstrated that γδ cells play a role in the regulation of airway responsiveness (Examples 1-6 and Lahn et al., Nature Med., 5:150-1156, 1999). In view of the increased number of γδ T cells in the TNF-α transgenic mice (Nakama et al., Exp. Lung Res., 24:57-70, 1998) and the findings that γδ T cells are activated by TNF-α (more so than aγδ T cells) (Lahn et al., J. Immunol., 160:5221-5230, 1998), the present inventors examined whether activated γδ T cells might play a role in the failure of TNF-α transgenic mice to develop AHR. To deplete γδ T cells, TNF-α transgenic mice and TNF-α deficient mice were treated with TCR-8 mAb 3 days before the first challenge. TNF-α deficient mice administered anti-TCR-δ failed to show any further increase in AHR (data not shown). In contrast, SP-C-TNF-α transgenic mice depleted of γδ T cells developed AHR while sham-treated controls did not (data not shown). This effect on AHR was not correlated with a cellular inflammatory response: in both OVA sensitized and challenged TNF-α deficient and transgenic mice, there were no significant differences in the composition of inflarmnatory cells in the BALF following depletion of γδ T cells (data not shown). In summary, these data confirm that γδ T cells play an important role in the pathophysiology of the development of AHR and, based on the data in the SP-C-TNF-α transgenic mice, a possibility as to the mechanism is suggested. Thus, the interactions between TNF-α and γδ T cells may be central in regulating airway tone following airway exposure to allergen. These findings emphasize complex but important contributions of TNF-α to the overall regulation of allergic inflammatory responses in the lung and the development of altered airway function in part through interactionswith γδ T cells. The additional finding that the absence of TNF-α was associated with increased levels of IL-1O, an important factor in the development of AHR, reveals another potential mechanism by which TNF-α may control airway responsiveness, that is through suppression of IL-10. While various embodiments of the present invention have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. It is to be expressly understood, however, that such modifications and adaptations are within the scope of the present invention, as set forth in the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>Diseases involving inflammation are characterized by the influx of certain cell types and mediators, the presence of which can lead to tissue damage and sometimes death. Diseases involving inflammation are particularly harmful when they afflict the respiratory system, resulting in obstructed breathing, hypoxemia, hyperapnia and lung tissue damage. Obstructive diseases of the airways are characterized by airflow limitation (i.e., airflow obstruction or narrowing) due to constriction of airway smooth muscle, edema and hypersecretion of mucus leading to increased work in breathing, dyspnea, hypoxemia and hypercapnia. A variety of inflammatory agents can provoke airflow limitation including allergens, cold air, exercise, infections and air pollution. In particular, allergens and other agents in allergic or sensitized mammals (i.e., antigens and haptens) cause the release of inflammatory mediators that recruit cells involved in inflammation. Such cells include lymphocytes, eosinophils, mast cells, basophils, neutrophils, macrophages, monocytes, fibroblasts and platelets. Inflammation results in airway hyperresponsiveness (AHR). A variety of studies have linked the degree, severity and timing of the inflammatory process with the degree of airway hyperresponsiveness. Thus, a common consequence of inflammation is airway hyperresponsiveness. Currently, therapy for treatment of inflammatory diseases involving AHR, such as moderate to severe asthma and chronic obstructive pulmonary disease, predominantly involves the use of glucocorticosteroids and other anti-inflammatory agents. These agents, however, have the potential of serious side effect, including, but not limited to, increased susceptibility to infection, liver toxicity, drug-induced lung disease, and bone marrow suppression. Thus, such drugs are limited in their clinical use for the treatment of lung diseases associated with airway hyperresponsiveness. The use of anti-inflammatory and symptomatic relief reagents is a serious problem because of their side effects or their failure to attack the underlying cause of an inflammatory response. There is a continuing requirement for less harmful and more effective reagents for treating inflammation. Thus, there remains a need for processes using reagents with lower side effect profiles, less toxicity and more specificity for the underlying cause of AHR. Airway hyperresponsiveness (AHR) is the result of complex pathophysiological changes in the airway. A variety of studies have linked the degree, severity and timing of the inflammatory process with the degree of airway hyperresponsiveness. However, the mechanisms leading to AHR are still poorly understood and can be attributed to both immune-dependent and immune-independent mechanisms. Essentially all of the T cell-mediated effects described so far are in the former category. However, T cells from hyperresponsive mice can increase baseline airway tone in hyporesponsive mice after cell transfer. Because of their constitutive presence in the normal lung, γδ T cells have been investigated with regard to their potential role in airway responses. γδ T cells have been observed to proliferate and produce cytokines in many diseases. In addition, studies in animal models have provided evidence that these cells contribute to host resistance against infections (Hiromatsu et al., 1992 , J. Exp. Med. 175:49), and that they can influence inflammation (Fu et al., 1994 , J. Immunol. 153:3101), epithelial regeneration (Boismenu et al., 1994 , Science 266:1253), and mucosal tolerance to antigens (Fujihashi et al., 1992 , J. Exp. Med. 175:695; McMenamin et al., 1994, supra). Investigators are still determining what stimuli trigger γδ T cell reactivity, and to what extent γδ T cell activating stimuli differ from those of αβ T cells and B lymphocytes. It is known that γδ T cells respond during bacterial and viral infections, although they have not been readily linked to antigen-specific adaptive immunity. A number of studies have investigated the presence and role of γδ T cells in diseases of the airways. Pawankar et al. noted the mucosal changes at the site of allergic inflammation in patients with perennial allergic rhinitis and chronic infective rhinitis includes an oligoclonal expansion and activation of Vγ1/Vδ + T cells (Pawankar and Ra, 1996 , J. Allergy Clin. Immunol. 98:S248-62). Molfino et al. showed that much of the γδ T cell population found in broncho alveolar lavage (BAL) fluid in humans derives from clonally expanded T cells (Molfino et al., 1996 , Clin. Exp. Iminunol. 104:144-153). Spinozzi et al., measuring γδ T cells in the BAL fluid from patients with asthma, concluded that allergen-specific, steroid-sensitive γδ T cells may be one of the cellular components involved in the airway inflammation that characterizes allergic bronchial asthma (Spinozzi et al., 1996 , Ann. Intern. Med. 124:223-227 and 1995 , Mol. Med. 1:821-826). Moreover, it has been noted that in patients with respiratory conditions including Bordetella pertussin infection (whooping cough) and asthma, circulating γδ T cells are decreased. It has been suggested that the reason for this decrease is the dispatch of γδ T cells to the site of inflammation in the lung. (Bertotto et al., 1997, Acta Paediatr. 86:114-115; Schauer et al., 1991, Clin. Exp. Immunol. 86:440-443; Krejsek et al., 1998, Allergy 53;73-77). Many of the studies directed to γδ T cells and airway diseases have directly suggested that γδ T cells are proinflammatory, promoting acute airway sensitization, increases in cytokine levels suggested to be involved in allergic inflammation, regulation of allergic αβ T-cell and allergen specific B-cell responses, and/or allergen-induced eosinophilia and IgE responses (e.g., McMenamin et al., 1994 , Science 265:1869-1871; Zuany-Amorim et al., 1998, supra; Schramm et al., 2000 , Am. J. Respir. Cell Mol. Biol. 22:218-225; Schramm et al., 1999, International Conference of the American Thoracic Society; vol. 159:A255 (American Journal of Respiratory and Critical Care Medicine, San Diego, Calif.)). Some investigators, alternatively, have concluded that γδ T cells do not play a significant role in airway allergic inflammation. For example, Chen et al. noted, similar to other investigators discussed above, that allergic asthmatics have reduced γδ T cells in the peripheral blood. However, Chen et al. concluded that no significant correlation existed between the levels of γδ T cells and IgE present in the peripheral blood (Chen et al., 1996 , Clin. Exp. Iminunol. 26:295-302). Although allergic asthmatics have reduced γδ T cells with reciprocally elevated eosinophil numbers in the peripheral blood, Chen et al. asserted that this does not indicate that the reduction of γδ T cells correlates with the predominance of eosinophilia or IgE levels in diseased populations. Jaffar et al. described a role for au, but not γδ, T cells in allergen-induced Th2 cytokine production from asthmatic bronchial tissue (Jaffar et al., 1999 , J. Immunol. 163:6283-6291). Fajac et al., 1997, Eur. Resp. J 10:633-638 investigated the role of heat shock proteins and γδ T cells in patients with mild atopic asthma, and concluded that neither heat shock proteins nor γδ T cells play an important role in inflammatory and immune responses in mild asthma. Therefore, prior to the present invention, those of skill in the art either considered γδ T cells to play an insignificant role, if any, in diseases of the airways, or believed that γδ T cells were proinflammatory cells which contributed to the development of acute airway hyperresponsiveness and other events associated with inflammation. | <SOH> SUMMARY OF THE INVENTION <EOH>The present inventors have discovered that yb cells can regulate airway function in an aid T cell-independent manner, identifying them as important cells in pulmonary homeostasis. This function of γδ T cells differs from previously described immune-dependent mechanisms and may reflect their interaction with innate systems ofhost defense. Specifically, in contrast to other studies that emphasized their role in the modification of allergen-specific αβ T cell and B-cell responses, the present inventors have found that γδ T cells maintain normal airway responsiveness independently of αβ T cells. One embodiment of the present invention relates to a method to reduce airway hyperresponsiveness in a mammal. The method includes the step of increasing γδ T cell action in a mammal that has, or is at risk of developing, a respiratory condition associated with airway hyperresponsiveness. In one aspect, the step of increasing γδ T cell action comprises increasing the number of γδ T cells in the lung tissue of the mammal. For example, the step of increasing can comprise removing γδ T cells from the mammal, inducing the γδ T cells to proliferate ex vivo to increase the number of the γδ T cells, and returning the γδ T cells to the lung tissue of the mammal. In another aspect, the step of increasing γδ T cell action comprises activating γδ T cells in the mammal. Activating γδ T cells can be performed ex vivo or in vivo. In one embodiment of the method, the step of increasing γδ T cell action comprises administering an agent to the mammal that activates γδ T cells in the mammal. Such an agent can be any agent suitable for activating γδ T cells. In one aspect, the agent is a protein comprising a BiP-binding motif, wherein the protein is administered in an amount effective to induce proliferation of γδ T cells in the mammal. In another aspect, the agent is selected from the group consisting of a glycosylated protein and a glycosylated peptide. In another aspect, the agent is selected from the group consisting of polyGT and poly GAT (1:1:1). In yet another embodiment, the agent is selected from the group of: synthetic GC, synthetic AT and other oligonucleotides. In yet another aspect, the agent is a mycobacterial product. In another aspect, the agent is a Listeria cell wall product. In another aspect, the agent is a cardiolipin. In yet another aspect, the agent is tumor necrosis factor-α (TNF-α). In one aspect, the agent is an antibody that specifically binds to a γδ T cell receptor and activates the γδ T cells. Preferably, the agent is an antibody that specifically binds to a γδ T cell receptor (TCR) from a γδ T cell subset that is particularly suitable for regulation of airway hyperresponsiveness. Such a TCR includes, but is not limited to, a murine TCR comprising Vγ4 and a human TCR comprising Vγ1. In one aspect of the method of the present invention, the agent is targeted to γδ T cells in the mammal. Preferably, the agent is targeted to γδ T cells in the lung tissue of the mammal. In one embodiment, the agent is targeted to γδ T cell subsets that are particularly suitable for regulation of airway hyperresponsiveness, such γδ T cells having a T cell receptor (TCR) selected from: a murine TCR comprising Vγ4 and a human TCR comprising Vγ1. In one aspect, the agent comprises: (a) an antibody that specifically binds to a molecule on the cell surface of γδ T cells; and (b) a compound that activates the γδ T cells, wherein the compound is linked to the antibody of (a). The compound can include, but is not limited to: a protein comprising a peptide having a BiP-binding motif, a glycosylated protein or peptide, polyGT, polyGAT (1:1:1), synthetic GC, synthetic AT, a mycobacterial product, a Listeria cell wall product, cardiolipin, TNF-α, and an antibody that specifically binds to a γδ T cell receptor and activates the receptor. In one aspect of the present method, the agent is administered to the lung tissue of the mammal. In a preferred embodiment, the agent is administered by a route selected from the group consisting of inhaled, intratracheal and nasal routes. Preferably, the agent is administered to the animal in an amount effective to reduce airway hyperresponsiveness in the animal as compared to prior to administration of the agent. In one aspect, the agent is administered with a pharmaceutically acceptable excipient. Preferably, the method of the present invention increases γδ T cell action within between about 1 hour and 6 days of an initial diagnosis of airway hyperresponsiveness in the mammal. In another embodiment, the γδ T cell action is increased within less than about 72 hours of an initial diagnosis of airway hyperresponsiveness in the mammal. In another embodiment, the γδ T cell action is increased prior to development of airway hyperresponsiveness in the mammal. Preferably, the step of increasing γδ T cell action decreases airway methacholine responsiveness in the mammal, and/or reduces airway hyperresponsiveness of the mammal such that the FEV 1 value of the mammal is improved by at least about 5%. It is also preferred that the step of increasing γδ T cell action improves the mammal's PC 20methacholin FEV 1 value such that the PC 20 methacholineFEVI value obtained before the step of increasing γδ T cell action when the mammal is provoked with a first concentration of methacholine is substantially the same as the PC 20methacholin FEV 1 value obtained after increasing γδ T cell action when the mammal is provoked with double the amount of the first concentration of methacholine. Preferably, the first concentration of methacholine is between about 0.01 mg/ml and about 8 mg/ml. The method of the present invention is suitable for treating airway hyperresponsiveness associated with any condition including, but not limited to, airway hyperresponsiveness is associated with a disease selected from the group consisting of chronic obstructive disease of the airways and asthma. Yet another embodiment of the present invention relates to a method to identify a compound that reduces or prevents airway hyperresponsiveness associated with inflammation. The method includes the steps of: (a) contacting a putative regulatory compound with a γδ T cell; (b) detecting whether the putative regulatory compound increases the action of the γδ T cell; and, (c) administering the putative regulatory compound to a non-human animal in which airway hyperresponsiveness can be induced, and identifying animals in which airway hyperresponsiveness is reduced or prevented as compared to in the absence of the putative regulatory compound. A putative regulatory compound that increases γδ T cell action and that reduces or prevents airway hyperresponsiveness in the non-human animal is indicated to be a compound for reducing or preventing hyperresponsiveness. Preferably, step (b) of detecting is selected from the group consisting of measurement proliferation of the γδ T cell, measurement of cytokine production by the γδ T cell, measurement of calcium mobilization in the γδ T cell, measurement of cytokine receptor expression by the γδ T cell, measurement of.CD69 upregulation by the γδ T cell, measurement of upregulation, of CD44 by the γδ T cell, and measurement of cytoskeletal reorganization by the γδ T cell. | 20040324 | 20090901 | 20050113 | 96134.0 | 0 | ROONEY, NORA MAUREEN | MODULATION OF GAMMA DELTA T CELLS TO REGULATE AIRWAY HYPERRESPONSIVENESS | SMALL | 1 | CONT-ACCEPTED | 2,004 |
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10,808,894 | ACCEPTED | Remotely accessed virtual recording room | An audio/video stream recording, storage, and delivery system 10 utilizes an Internet-based browser connection. The system 10 includes recording software 20, storage memory 30, a code generator 40, and a user interface 50. Preferably, the recording software 20 is located on the host back end 60 where it processes and records audio and video material that originates from the user front end 70 and is streamed to the host back end. The storage memory 30, which is also located on the host back end 60, stores the recorded audio and video material. The user interface 50 to the system provides a user located at the user front end 70 with remote access to a virtual recording room. The user interface 50 further enables the user to record audio and video material streamed from the user front end 70 by activating the recording software 20 located on the host back end 60. This is accomplished without requiring recording functionality on the user front end 70. The code generator 30 produces code associated with the recorded audio and video material. This code can be easily copied and pasted to an additional location 80, such as an auction website. Activating the code pasted at the additional location 80 provides access to the recorded audio and video material from the additional location while allowing the recorded audio and video material to remain stored at the host back end 60. | 1. An Internet-based recording method that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end, wherein the user front end requires only a microphone, a camera, and access to the Internet browser, the method comprising: recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; storing the recorded audio and video material on the host back end; and providing access to the recorded audio and video material. 2. The method of claim 1, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 3. The method of claim 1, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 4. The method of claim 1, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at an additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 5. The method of claim 4, wherein the pointer is a hyperlink. 6. The method of claim 1, wherein recording and storing the audio and video material further comprises: producing hypertext markup language code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material. 7. The method of claim 6, wherein providing access to the recorded audio and video material comprises: enabling access to the recorded audio and video material stored at the host back end from at least one additional location by copying the hypertext markup language code produced at the host back end and pasting the hypertext markup language code to the at least one additional location. 8. The method of claim 7, wherein the at least one additional location is an auction site. 9. The method of claim 1, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be edited from the user front end. 10. The method of claim 9, wherein the recorded audio and video material includes a recorded audio portion and a recorded video portion, and wherein enabling recorded audio and video material on the host back end to be edited from the user front end comprises: in response to input from the user front end, enabling audio material to be re-dubbed over the recorded audio portion of the recorded audio and video material stored at the host back end while retaining the recorded video portion of the recorded audio and video material stored at the host back end. 11. The method of claim 1, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, copying the recorded audio and video material stored at the host back end to at least one additional location. 12. The method of claim 1, wherein providing access to the recorded audio and video material comprises: enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end, wherein the additional audio material, video material, or audio and visual material originates from the user front end. 13. An Internet-based recording method that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end, the method comprising: recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; storing the recorded audio and video material on the host back end; generating code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material; and enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio and video material from the additional location. 14. The method of claim 13, further comprising: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 15. The method of claim 13, further comprising: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 16. The method of claim 13, wherein enabling the generated code to be copied and pasted to an additional location comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at the additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 17. The method of claim 16, wherein the pointer is a hyperlink. 18. The method of claim 13, wherein the generated code is hypertext markup language that is associated with and linked to the recorded and stored audio and video material, thereby facilitating access to the recorded and stored audio and video material from the additional location. 19. The method of claim 18, wherein the additional location is an auction site. 20. An Internet-based recording method that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end, the method comprising: uploading photographic still material to the host back end from the user front end; recording audio material over the Internet browser connection that is linked with the photographic still material, wherein audio material originates from the user front end and is recorded on the host back end without requiring recording functionality on the user front end; storing the recorded audio material and the linked photographic still material on the host back end; generating code associated with the recorded audio material and the linked photographic still material to facilitate accessing the recorded audio material and the linked photographic still material; and enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio material and the linked photographic still material from the additional location. 21. The method of claim 20, further comprising: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 22. The method of claim 20, further comprising: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 23. The method of claim 20, wherein enabling the generated code to be co pied and pasted to an additional location comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at the additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 24. The method of claim 20, wherein the pointer is a hyperlink. 25. The method of claim 20, wherein the generated code is hypertext markup language that is associated with and linked to the recorded and stored audio and video material, thereby facilitating access to the recorded and stored audio and video material from the additional location. 26. The method of claim 20, wherein the additional location is an auction site. 27. The method of claim 20, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be edited from the user front end. 28. The method of claim 20, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, copying the recorded audio and video material stored at the host back end to at least one additional location. 29. The method of claim 20, wherein providing access to the recorded audio and video material comprises: enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end, wherein the additional audio material, video material, or audio and visual material originates from the user front end. 30. An Internet-based recording system that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end, the system comprising: recording software located on the host back end, wherein the recording software processes and records audio and video material on the host back end that originates from the user front end; storage located on the host back end for storing the recorded audio and video material; an interface that provides a user at the user front end with access to a virtual recording room and enables the user to record audio and video material originating from the user front end by activating the recording software on the host back end without requiring recording functionality on the user front end; a code generator that produces code associated with the recorded audio and video material, wherein the code facilitates accessing the recorded audio and video material, and wherein the code is copyable and pasteable to an additional location, thereby providing access to the recorded audio and video material from the additional location while the recorded audio and video material remains stored at the host back end. 31. The system of claim 30, further comprising: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 32. The system of claim 30, further comprising: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 33. The system of claim 30, wherein enabling the generated code to be copied and pasted to an additional location comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at the additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 34. The system of claim 30, wherein the pointer is a hyperlink. 35. The system of claim 30, wherein the generated code is hypertext markup language that is associated with and linked to the recorded and stored audio and video material, thereby facilitating access to the recorded and stored audio and video material from the additional location. 36. The system of claim 30, wherein the additional location is an auction site. 37. The system of claim 30, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be edited from the user front end. 38. The system of claim 30, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, copying the recorded audio and video material stored at the host back end to at least one additional location. 39. The system of claim 30, wherein providing access to the recorded audio and video material comprises: enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end, wherein the additional audio material, video material, or audio and visual material originates from the user front end. 40. A Wi-Fi based recording method that performs all audio and video recording functions over an Wi-Fi connection established between a user front end and a host back end, the method comprising: recording audio and video material over an Wi-Fi connection using a personal digital assistant, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; storing the recorded audio and video material on the host back end; generating code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material; and enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio and video material from the additional location. 41. The method of claim 40, further comprising: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 42. The method of claim 40, further comprising: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 43. The method of claim 40, wherein enabling the generated code to be copied and pasted to an additional location comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at the additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 44. The method of claim 40, wherein the pointer is a hyperlink. 45. The method of claim 40, wherein the generated code is hypertext markup language that is associated with and linked to the recorded and stored audio and video material, thereby facilitating access to the recorded and stored audio and video material from the additional location. 46. The method of claim 40, wherein the additional location is an auction site. 47. The method of claim 40, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be edited from the user front end. 48. The method of claim 40, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, copying the recorded audio and video material stored at the host back end to at least one additional location. 49. The method of claim 40, wherein providing access to the recorded audio and video material comprises: enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end, wherein the additional audio material, video material, or audio and visual material originates from the user front end. 50. An wireless mobile communications based recording method that performs all audio and video recording functions over a wireless mobile connection established between a user front end and a host back end, the method comprising: recording audio and video material over an wireless mobile connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; storing the recorded audio and video material on the host back end; generating code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material; and enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio and video material from the additional location. 51. The method of claim 50, further comprising: enabling recorded audio and video material on the host back end to be reviewed at the user front end. 52. The method of claim 50, further comprising: enabling recorded audio and video material on the host back end to be re-recorded from the user front end. 53. The method of claim 50, wherein enabling the generated code to be copied and pasted to an additional location comprises: in response to input from the user front end, linking the recorded audio and video material stored at the host back end to a pointer that is placed at the additional location, wherein activating the pointer provides access to the recorded audio and video material stored at the host back end. 54. The method of claim 50, wherein the pointer is a hyperlink. 55. The method of claim 50, wherein the generated code is hypertext markup language that is associated with and linked to the recorded and stored audio and video material, thereby facilitating access to the recorded and stored audio and video material from the additional location. 56. The method of claim 50, wherein the additional location is an auction site. 57. The method of claim 50, wherein providing access to the recorded audio and video material comprises: enabling recorded audio and video material on the host back end to be edited from the user front end. 58. The method of claim 50, wherein providing access to the recorded audio and video material comprises: in response to input from the user front end, copying the recorded audio and video material stored at the host back end to at least one additional location. 59. The method of claim 50, wherein providing access to the recorded audio and video material comprises: enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end, wherein the additional audio material, video material, or audio and visual material originates from the user front end. | FIELD OF THE INVENTION This invention relates generally to a remotely accessed virtual recording room, and more particularly to an audio/video stream recording, storage, and delivery system and method. BACKGROUND OF THE INVENTION With the continual increase of online transactions there has been an increasing need to improve the capabilities of online business related communication. One area where this is particularly true is in competitive sale exchanges, such as online auctions. The greater a seller's ability to showcase products, the more successful their online auctions sales are bound to become. With the number of online auctions growing daily, sellers are continuously looking for ways to improve the success of these auctions. Sellers are continuously looking for techniques or technology that will enable them to better explain what the products are that they are selling to potential buyers, as well as why those potential buyers should want the seller's products. Sellers also want to be able to effectively demonstrate how their products work. Additionally, sellers sometimes need to be able to demonstrate the authenticity of their products. Accordingly, people are continuously looking for ways to enhance their product listings and sales volume. Unfortunately, new systems and methods for increasing the capabilities of online business-related communications and transactions often result in increased intellectual complexity and/or increased computer system requirements. This tendency is undesirable because another main avenue for increasing the productively of online business-related communications and transactions is to increase the number of people who are participating in these online business-related transactions. Accordingly, it would be highly valuable if any new systems and methods for increasing the capabilities of online business-related communications and transactions also could be simple enough to help attract new users to the online business market and also not have extensive computer system requirements. Accordingly, there has been a long existing need for a system that improves the level of communication possible with respect to online business-related transactions. Further, there is a continuing need for an improved system and/or method that is simple, efficient, and does not have extensive computer system requirements. Accordingly, those skilled in the art have long recognized the need for a system and method that addresses these and other issues. SUMMARY OF THE INVENTION Briefly, and in general terms, a preferred embodiment of the claimed invention resolves the above and other issues by providing an audio/video stream recording, storage, and delivery system. A preferred embodiment provides an Internet-based recording system that performs all audio and video stream recording over an Internet browser connection established between a user front end and a host back end. A host is this environment is generally defined as a company that is utilizing an audio/video stream recording, storage, and delivery system of the claimed invention. In one preferred embodiment, the system includes recording software, storage memory, a user interface, and a code generator. Preferably, the recording software, which is located on the host back end, processes and records audio and video material that originates from the user front end and is streamed to the host back end. The storage memory, which is located on the host back end, then stores the recorded audio and video material. In a preferred embodiment, the user interface to the audio/video stream recording, storage, and delivery system provides a user at the user front end with remote access to a virtual recording room. The user interface further enables the user to record audio and video material streamed from the user front end by activating the recording software residing on the host back end. Advantageously, this is accomplished without requiring recording functionality on the user front end. Preferably, the code generator produces code associated with the recorded audio and video material. The user interface is configured to facilitate easily copying and pasting the code to an additional location, such as an auction website. The code facilitates accessing the recorded audio and video material stored at the host back end from the additional location at which the code has been pasted. In this manner, activating the pasted code at the additional location provides access to the recorded audio and video material from the additional location while allowing the recorded audio and video material to remain stored at the host back end. Additionally, another preferred embodiment of the claimed invention is directed towards an Internet-based recording method that performs all audio and video stream recording over an Internet browser connection established between a user front end and a host back end. Preferably, the components required at the user front end include only a microphone, a camera, and access to the Internet browser. In one preferred embodiment, the method includes: (1) recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (2) storing the recorded audio and video material on the host back end; and (3) providing access to the recorded audio and video material. In accordance with one aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling the recorded audio and video material on the host back end to be reviewed at the user front end. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling recorded audio and video material on the host back end to be re-recorded from the user front end. In accordance with still another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes linking the recorded audio and video material stored at the host back end to a pointer that is located in at least one additional location, in response to input from the user front end. Accordingly, activating the pointer then provides access to the recorded audio and video material stored at the host back end. In one preferred embodiment, the pointer includes a hyperlink. In accordance with another aspect of the preferred embodiment, the step of recording and storing the audio and video material further includes producing hypertext markup language code that is associated with the recorded and stored audio and video material. However, in other preferred embodiments of the invention, other coding languages (such as DHTML and the like) are utilized. This code facilitates accessing the recorded and stored audio and video material. In accordance with yet another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes: enabling access to the recorded audio and video material stored at the host back end from an additional location by copying the hypertext markup language code produced at the host back end and pasting the hypertext markup language code to the additional location. In one preferred embodiment, the additional location is an auction website. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling recorded audio and video material on the host back end to be edited from the user front end. Preferably, recorded audio and video material includes a recorded audio portion and a recorded video portion. In one preferred embodiment, enabling recorded audio and video material on the host back end to be edited from the user front end includes, in response to input from the user front end, enabling audio material to be re-dubbed over the recorded audio portion of the recorded audio material while retaining the recorded video portion of the originally recorded audio and video material. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes, in response to input from the user front end, copying (or downloading) the recorded audio and video material stored at the host back end to at least one additional location. In accordance with still another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end. In such a preferred embodiment, the additional audio material, video material, or audio and visual material originates from the user front end. Another preferred embodiment of the claimed invention is also directed towards an Internet-based recording method that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end. In this additional preferred embodiment, the method includes: (1) recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (2) storing the recorded audio and video material on the host back end; (3) generating code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material; and (4) enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio and video material from the additional location. In one preferred embodiment, the generated code is hypertext markup language that is associated with, and linked to, the recorded and stored audio and video material. In this manner, the associated code facilitates access to the recorded and stored audio and video material from the additional location. Yet another preferred embodiment of the claimed invention is directed towards a similar Internet-based recording method that performs all audio recording functions over an Internet browser connection established between a user front end and a host back end. In a preferred embodiment, the method includes: (1) uploading photographic still material to the host back end from the user front end; (2) recording audio material, over the Internet browser connection, to link the audio material with the photographic still material, wherein audio material originates from the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (3) storing the recorded audio material and the linked photographic still material on the host back end; (4) generating code associated with the recorded audio material and the linked photographic still material to facilitate accessing the recorded audio material and the linked photographic still material; and (5) enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio material and the linked photographic still material from the additional location. Still another preferred embodiment of the claimed invention is directed towards a Wi-Fi (Wireless Fidelity, i.e., generally referring to any type of IEEE 802.11 network) recording method that performs at least part of the audio and video recording functions over a Wi-Fi connection established between a user front end and a host back end. In such a preferred embodiment, the method includes recording audio and video material over a Wi-Fi connection using a personal digital assistant. The remainder of the Wi-Fi recording method is generally performed in a similar fashion to the Internet-based recording method described above. Finally, another preferred embodiment of the claimed invention is directed towards a wireless mobile communications-based recording method that performs all (or at least part) of the audio and video recording functions over a wireless mobile connection established between a user front end and a host back end. In such a preferred embodiment, the method includes recording audio and video material over a wireless mobile connection. The remainder of the wireless mobile communications-based recording method is generally performed in a similar fashion to the Internet-based recording method described above. Other features and advantages of the claimed invention of the present application will become apparent from the following detailed description, taken in conjunction with the achosting drawings, which illustrate by way of example, the features of the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an Internet based audio/video stream recording, storage, and delivery system that includes recording software, storage memory, a code generator, and a user interface, constructed in accordance with the claimed invention of the present application; FIG. 2 illustrates an audio/video stream recording, storage, and delivery method, constructed in accordance with the claimed invention of the present application; FIG. 3 illustrates a Wi-Fi based audio/video stream recording, storage, and delivery system that includes recording software, storage memory, a code generator, and a user interface, constructed in accordance with the claimed invention of the present application; and FIG. 4 illustrates a mobile wireless communication based audio/video stream recording, storage, and delivery system that includes recording software, storage memory, a code generator, and a user interface, constructed in accordance with the claimed invention of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the remotely accessed virtual recording room, constructed in accordance with the claimed invention, provides an audio/video stream recording, storage, and delivery system and method. A preferred embodiment of the claimed invention provides an Internet-based recording system that performs audio and video stream recording over an Internet browser connection established between a user front end and a host back end, without requiring any recording functionality at the user front end. Referring now to the drawings, wherein like reference numerals denote like or corresponding parts throughout the drawings, and more particularly to FIGS. 1-2, there is shown an audio/video stream recording, storage, and delivery system. Specifically, FIGS. 1-2 show a preferred embodiment of an audio/video stream recording, storage, and delivery system 10 that utilizes an Internet-based browser connection. In one preferred embodiment, the system 10 includes recording software 20, storage memory 30, a code generator 40, and a user interface 50. Advantageously, users of a preferred audio/video stream recording, storage, and delivery system 10 do not require any specific expertise, special software, local server space, or special equipment. In one preferred embodiment, the web-based audio/video stream recording, storage, and delivery system 10 is utilized in conjunction with online auctions, such as those available on eBay and Yahoo Auction. While some preferred embodiments are described with respect to online auctions, those skilled in the art will appreciate that other preferred embodiments are utilized in conjunction with non-auction systems and services, without departing from the scope of the claimed invention. These other preferred embodiments may be either Internet-based, or alternatively may utilize some other type of network, including by way of example only and not by way of limitation, Wi-Fi systems, other wireless LAN (Local Area Network) systems, and mobile wireless communication systems. In one preferred embodiment, the audio/video stream recording, storage, and delivery system 10 allows a user to quickly and easily record audio/video material, and place the material inside a third party online auction (e.g., eBay, Yahoo auctions, or international auction sites). Initially, a user accesses a web page that includes the user interface 40 of the recording, storage, and delivery system 10. The user interface 40 provides a virtual recording room for the user that is access through a web browser. As described above, no special software is needed in order to utilize the recording, storage, and delivery system 10 of the claimed invention beyond a standard web browser, such as is required to view any typical web page. This is in contrast to traditional video recording and player systems that typically require some type of additional “plug in” or other additional custom software application to be downloaded and installed locally. The only equipment required by the recording, storage, and delivery system 10 of the claimed invention is a simple web camera and microphone. The virtual recording room makes it easy for the user to sign up (e.g., create an account) and to start recording any number of audio/video streams. Preferably, the user can “retake” an audio/video stream as often as desired. The user interface 40 of the recording, storage, and delivery system 10 then provides the user with the code required to link and to allow access to the user's video from within the eBay or other online auction website with a simple click of a button. The audio/video streams created by the user are stored in storage memory 30, such as on a server, located at the host back end 60. Preferably, the recording software 20 is located on the host back end 60 where it processes and records audio and video material that originates from the user front end 70 and is streamed to the host back end. The storage memory 30 (e.g., a server), which is also preferably located on the host back end 60, then stores the recorded audio and video material. In a preferred embodiment, the recorded audio and video material (e.g., audio/video streams) are stored on audio/video servers at the host back end 60, and thus, do not require that the user have access to local servers or any other type of local storage memory 30. Preferably, the audio/video streams are immediately accessible for review using the system video player in the user interface 50 once the audio/video streams have been recorded. Additionally, in a preferred embodiment of the system 10, the user can also instantly update the audio/video streams using the virtual recording room of the user interface. Such an update includes, by way of example only and not by way of limitation, re-recording of the audio/video streams, editing of the audio/video streams, re-dubbing only the audio portion of the audio/video streams, attaching additional audio and/or video material to the original audio/video streams, and annotating the audio/video streams. Preferably, the code generator 40 produces code associated with the recorded audio and video material. The code facilitates accessing the recorded audio and video material from any additional location 80 where the code has been pasted. Activating the code enables access to the recorded audio and video material stored on the servers 30, which are located at the host back end 60. Accordingly, with the click of a button, the necessary code is saved to the user's clipboard, where the code is ready to be easily pasted into a third-party website, such as the user's auction listing description. This code gives all the necessary information for a system video player to appear on the third-party website (e.g. an auction listings) and to show the user's recorded audio and video material. As described above, in a preferred embodiment, the code produced is hypertext markup language code. Preferably, the code provides access to the recorded audio and video material by copying the hypertext markup language code produced at the host back end 60 and allowing the user to paste the hypertext markup language code to the additional location 80. In this manner, activating the pasted code at the additional location 80 provides access to the recorded audio and video material from the additional location 80 while allowing the recorded audio and video material to remain stored at the host back end 60. It will be appreciated however, that other coding languages that accomplish the same functionality may also be used, without departing some the scope of the claimed invention. In a preferred embodiment, the user interface 50 to the audio/video stream recording, storage, and delivery system 10 provides a user at the user front end 70 with remote access to the virtual recording room. The user interface 50 further enables the user to record audio and video material streamed from the user front end 70 by activating the recording software 20, which is located on the host back end 60. The user interface 50 is configured to facilitate easily copying and pasting the code to an additional location 80, such as an auction website. Advantageously, this is accomplished without requiring recording functionality on the user front end 70. The user interface 50 only requires an Internet browser and standard Internet plug-ins. A preferred embodiment includes a unique user interface 50 that facilitates the easy recording of any number of videos (either with or without accompanying audio), and thereafter placing these videos into online auction listings and auction stores. Preferably, the simplicity of the user interface 50 is achieved through the web-based, remotely accessible, virtual recording room. In a preferred embodiment, the user interface 50 enables a user to enter a virtual recording room in which the user can easily and intuitively select any number of audio/video streams, then record, playback, and/or re-record the audio/video streams as often as desired. The user interface 50 of the audio/video recording, storage, and delivery system 10 enables a user to place the code required for use by a third-party website, such as an auction site, on that third-party website using traditional copying and pasting techniques. In a preferred embodiment, the user interface 50 provides access to the recording software 20, and in this manner, enables the recorded audio and video material stored on the host back end 60 to be reviewed at the user front end 70. This same access to recording software 20 via the user interface 50 also enables recorded audio and video material on the host back end 60 to be re-recorded from the user front end 70. Furthermore, user interface 50 facilitates linking the recorded audio and video material stored at the host back end 60 to a pointer residing at an additional location 80. Accordingly, activating the pointer preferably provides access to the recorded audio and video material stored at the host back end 60. Another preferred embodiment of an Internet-based recording method performs all audio and video stream recording over an Internet browser connection established between a user front end 70 and a host back end 60. In one such embodiment, the method includes: (1) recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end 70 and is recorded on the host back end 60 without requiring recording functionality residing on the user front end 70; (2) storing the recorded audio and video material on the host back end 60; and (3) providing access to the recorded audio and video material. In a preferred embodiment, the method further includes enabling recorded audio and video material on the host back end 60 to be edited from the user front end 70. With respect to another aspect, the preferred method includes copying or downloading the recorded audio and video material stored at the host back end 60 to at least one additional location 80. Preferably, the method includes enabling additional audio material, video material, or audio/visual material to be uploaded and attached to the previously recorded audio and video material stored on the host back end 60. In such a preferred embodiment, the additional audio material, video material, or audio and visual material originates from the user front end 70. A more comprehensive description of a preferred method for audio/video stream recording, storage, and delivery is described below, with respect to FIG. 2. At Step 100, a user signs up or otherwise creates an account on a website 102 that is utilizing the recording, storage, and delivery method of the claimed invention. Various techniques can be used to purchase use of the recording, storage, and delivery method through a web browser, including by way of example only, and not by way of limitation, credit card and PayPal transactions. At Step 110, a unique Username and Password are assigned to this user. This allows a unique virtual recording room to be created in the user interface 50 that is accessed using this Username and Password. Accordingly, at Step 120, the user can log in directly to his or her own personalized virtual recording room 122. The personalized virtual recording room includes an icon for each video that the user has purchased the right to record (i.e., if the user has purchased the right to record and store ten audio/video streams, there would be icons for audio/video streams 1-10 in the user's personalized virtual recording room). In a preferred embodiment, the virtual recording room in the user interface 50 further includes typical video player buttons 132, such as RECORD, PLAY, PAUSE, STOP, and volume control. At Step 130, the user simply selects the video number that they desire to record in their recording room in order to begin the video recording process. The user then selects the RECORD button to record the selected video number. After the recording is complete, the user can play back the recorded audio/video stream to ensure satisfaction with the recorded material by pressing PLAY button. In a preferred embodiment, at Step 140, the user links their recorded audio/video material by clicking a code generator button, which generates a unique code for each recorded audio/video stream, and copies that code to the user's clipboard. This code is created differently, as described in further detail below, depending on whether the website at which the code is to be posted to is a full HTML (hypertext markup language) supported site 142 (such as eBay), or only a limited HTML supported site 144 (such as Yahoo Auction). At Step 150, the user then opens a website to which they wish to place their code, such as an eBay or Yahoo Auction webpage, and at Step 160, pastes the generated code into the respective additional location 80 at either eBay or Yahoo auction. Preferably, at Step 170, when the user completes the eBay or Yahoo submission, the video player utilized by the audio/video recording, storage, and delivery system 10 appears in the webpage, seamless with other items on the page. A preferred embodiment of the audio/video recording, storage, and delivery system 10 utilizes a Flash recording application. Within the Flash recording application, a user who purchases multiple videos can select which video to record. Specifically, this application sends the user to a frame in the timeframe that includes the audio/video recorder and gives the application definitions of the stream number, which is equivalent to the video number. Preferably, the other variables have already been defined. These include by way of example only, and not by way of limitation, the height and width of the player, the location of the player, and the appInstance (application instance), which is passed through an ASP-generated flashvar (flash variable) in the HTML page. Below are exemplary sample instructions that are utilized by the code generator 30, which are provided by way of example only, and not by way of limitation. These instructions create the text for easily pasting to an additional location 80, such as an online auction website. The following preferred embodiment instructions are for full HTML auctions, such as eBay: _root.createTextField(“mytext”,1,10,710,530,190); //COPY BUTTON see http://www.auctionvideo.com/record_thirty_new.htm _root.createTextFormat(“myformat”); myformat = new TextFormat( ); myformat.color = 0x000000; myformat.font = “Arial”; myformat.size = 10; myformat.leading = “−1”; mytext.multiline = true; mytext.wordWrap = true; //text below mytext.text = ‘<OBJECT classid=“clsid:D27CDB6E-AE6D-11cf-96B8-444553540000” codebase=“http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6, 0,0,0” WIDTH=“‘+swfWidth+’” HEIGHT=“‘+swfHeight+’” id=“play” ALIGN=“”> <PARAM NAME=“FlashVars” VALUE=“appInstance=‘+appInstance+’&streamNumber=‘+streamNumber+’”> <PARAM NAME=movie VALUE=“‘+swfLocation+’play.swf”> <PARAM NAME=quality VALUE=high> <PARAM NAME=bgcolor VALUE=#FFFFFF> <EMBED src=“‘+swfLocation+’play.swf” FLASHVARS=“appInstance=‘+appInstance+’&streamNumber=‘+streamNumber+’” quality=high bgcolor=#FFFFFF WIDTH=“‘+swfWidth+’” HEIGHT=“‘+swfHeight+’” NAME=“play” ALIGN=“”TYPE=“application/x-shockwave-flash” PLUGINSPAGE=“http://www.macromedia.com/go/getflashplayer”></EMBED></OBJECT>’; mytext.setTextFormat(myformat); The following preferred embodiment instructions are for limited HTML auctions, such as Yahoo Auction: _root.createTextField(“yahootext”,4,750,250,400,400); //COPY BUTTON see http://www.auctionvideo.com/record_thirty_new.htm //text below yahootext.text = ‘<a href=“http://www.auctionvideo.com/player.htm?appInstance= ‘+appInstance+’&streamNumber=‘+streamNumber+’”><img src=“http://www.auctionvideo.com/auctionvideobutton.jpg” width=“400” height=“108” border=“0”></a>’; yahootext.setTextFormat(myformat); Below are exemplary sample instructions that are utilized by the user interface 30, which are provided by way of example only, and not by way of limitation. These instructions are used to copy the generated code onto additional locations 80, such as auction websites. In a preferred embodiment, the FSCommand action is used to implement j avaScript, Visual Basic, and ActionScript, which automatically places the generated HTML code into the user's clipboard. The following preferred embodiment instructions are the ActionScript (button) instructions: on(release){ fscommand(“myCopyCBFunction”, mytext.text); } The following preferred embodiment instructions are the Visual Basic instructions: <SCRIPT LANGUAGE=“VBScript”> <!-- // Catch FS Commands in IE, and pass them to the corresponding JavaScript function. Sub testmovie_FSCommand(ByVal command, ByVal args) call testmovie_DoFSCommand(command, args) end sub // --> </SCRIPT> The following preferred embodiment instructions are the JavaScript instructions: <SCRIPT LANGUAGE=“JavaScript”> <!-- function testmovie_DoFSCommand(command, args) { if(command == “myCopyCBFunction”){ window.clipboardData.setData(‘Text’, args); } } Another preferred embodiment of an audio/video stream recording, storage, and delivery method is particularly advantageous for users without access to a web camera or for users with a slow Internet connection. In such a preferred method, the user simply uploads one or more previously recorded digital still images to the storage memory 30, (i.e., servers) located at the host back end 60. In one embodiment that is utilized in conjunction with an online auction, these previously recorded digital still images are of the item(s) that the user is selling. After the digital still images have been uploaded, the user enters the virtual recording room in the user interface 50. Next, the user selects the RECORD button, and moves through the images one by one while providing a streaming audio description of each photo that is recorded by the storage memory 30 at the host back end 60. As the audio is streamed to the host server 30, the recording software 20 tracks the correlation between the images and the audio being recorded. After the “slide show” of still pictures and associated audio material has been recorded, the user can review, record, and/or edit their show, just as in the previous preferred embodiment. When the user is satisfied, the user selects a “copy code” button, just as in the previous preferred embodiment. This prepares the HTML code to be pasted into a website at an additional location 80, such as the auction description at an auction website. In one preferred embodiment, this audio/video stream recording, storage, and delivery method is configured such that, as soon as a viewer accesses the auction webpage for that particular item, the recording, storage, and delivery method begins playing this “slide show.” Preferably, the viewer can replay the “slide show” after it has finished, as many times as desired. The following instructions are for the audio record/still upload preferred embodiment method: _global.conn_nc = new NetConnection( ); _global.server=“xxx.xxx.xxx.xxx”; _global.picXML_xml=new XML( ); _global.XML_URL=“http://www.auctionvideo.com/uploads/”+appInstance+“.xml”; _global.picture_array=new Array( ); _global.curPic=0; _global.recording=false; _global.recordLimitSeconds=60; _global.mic_mic=Microphone.get( ); mic_mic.setRate(11); conn_nc.onStatus = function(info) { var infomsg = info.code; trace(infomsg); if (infomsg == “NetConnection.Connect.Success”) { goGetTheStream(this); getTheSO(this); } else if (infomsg == “NetConnection.Connect.Rejected”) { } else if (infomsg == “NetConnection.Connect.Closed”) { } else if (infomsg == “NetConnection.Connect.Failed”) { } }; picXML_xml.ignoreWhite=true; picXML_xml.onLoad=function(suc){ if(suc){ _global.URL=“rtmp://”+server+“/ebay2/”+appInstance; for(i=0;this.firstChild.childNodes[i]!=null;i++){ o=new Object( ); o.jpegurl=this.firstChild.childNodes[i].attributes.jpegurl; o.picnum=this.firstChild.childNodes[i].attributes.picnum; picture_array.push(o); } _global.maxPic=picture_array.length; loadJPG( ); conn_nc.connect(URL); }else{ trace(“load failed”); } } setW = f_mc._width; setH = f_mc._height; _global.wOffset=f_mc._x; _global.hOffset=f_mc._y; back or forward too far _global.loadJPG = function( ) { _root.createEmptyMovieClip(“jpgLoader_mc”, 50); jpgLoader_mc.loadMovie(“http://www.auctionvideo.com/uploads/”+appInstance+“/”+picture— array[curPic].jpegurl); _root.onEnterFrame = function( ) { if ((jpgLoader_mc.getBytesLoaded( )>4) && (jpgLoader_mc.getBytesLoaded( ) == jpgLoader_mc.getBytesTotal( ))) { _root.onEnterFrame = null; jpgW = jpgLoader_mc._width; jpgH = jpgLoader_mc._height; if (jpgW>setW ∥ jpgH>setH) { overW = jpgW−setW; overH = jpgH−setH; if (overW>overH) { perc = jpgW/setW; jpgLoader_mc._width = jpgW/perc; jpgLoader_mc._height = jpgH/perc; newH = jpgLoader_mc._height; jpgLoader_mc._y = ((setH/2)− (Math.round(newH/2)))+hOffset; jpgLoader_mc._x = wOffset; } else { perc = jpgH/setH; jpgLoader_mc._width = jpgW/perc; jpgLoader_mc._height = jpgH/perc; newW = jpgLoader_mc._width; jpgLoader_mc._y = hOffset; jpgLoader_mc._x = ((setW/2)− (Math.round(newW/2)))+wOffset; } } else { newH = jpgLoader_mc._height; jpgLoader_mc._y = ((setH/2)−(Math.round(newH/2)))+hOffset; newW = jpgLoader_mc._width; jpgLoader_mc._x = ((setW/2)−(Math.round(newW/2)))+wOffset; } } }; checkButtons( ); }; _global.goGetTheStream=function(nc){ _global.slideShow_ns=new NetStream(nc); slideShow_ns.attachAudio(mic_mic); } _global.getTheSO=function(nc){ _global.slideShow_so=SharedObject.getRemote(“slideShow”,nc.uri,true); slideShow_so.onSync=function( ){ trace(“all connected up”); } slideShow_so.connect(nc); } _global.checkButtons=function( ){ if(curPic+1==maxPic){ a_pb.setEnabled(false); }else{ a_pb.setEnabled(true); } if(curPic==0){ b_pb.setEnabled(false); }else{ b_pb.setEnabled(true); } } _global.changeNum=function(a){ a=(Math.round(a*100)/100); return a; } function nextClick( ){ if(recording==true){ tempObj=new Object( ); tempObj.clickTime=changeNum(slideShow_ns.time); tempObj.direction=“next”; clickHolder_array.push(tempObj); delete tempObj; } curPic++; loadJpg( ); } function backClick( ){ if(recording==true){ tempObj=new Object( ); tempObj.clickTime=changeNum(slideShow_ns.time); tempObj.direction=“back”; clickHolder_array.push(tempObj); delete tempObj; } curPic−−; loadJpg( ); } function saveClick(comp){ if(comp.getLabel( )==“Record”){ publishTheAudio( ); comp.setLabel(“Stop”); }else{ saveTheData( ); comp.setLabel(“Record”); } } _global.publishTheAudio=function( ){ recording=true; _global.clickHolder_array=new Array( ); slideShow_ns.publish(appInstance,“record”); clearInterval(recordTimerInterval); _global.recordTimerInterval=setInterval(stopRecording,recordLimitSeconds*1000); } _global.stopRecording=function( ){ saveTheData( ); s_pb.setLabel(“Record”); } _global.saveTheData=function( ){ clearInterval(recordTimerInterval); slideShow_so.data.slideShow=clickHolder_array; recording=false; slideShow_ns.publish(false); delete clickHolder_array; curPic=0; loadJpg( ); } a_pb.setClickHandler(“nextClick”); b_pb.setClickHandler(“backClick”); s_pb.setClickHandler(“saveClick”); picXML_xml.load(XML_URL); stop( ); As mentioned above, other preferred embodiments may utilize other types of communication networks, including by way of example only and not by way of limitation, Wi-Fi systems, other wireless LAN systems, and mobile wireless communication systems. In the preferred embodiment shown in FIG. 3, a Wi-Fi based recording method performs at least part of the audio and video recording functions over a Wi-Fi connection established between a user front end 70 and a host back end 60. In such a preferred embodiment, the method includes recording audio and video material over a Wi-Fi connection using a personal digital assistant. In some preferred embodiments, the method includes recording audio and video material over a combined Wi-Fi and Internet network connection. Finally, in another preferred embodiment shown in FIG. 4, a wireless mobile communications-based recording method performs all audio and video recording functions over a wireless mobile connection established between a user front end 70 and a host back end 60. The remainder of the Wi-Fi based recording method and the mobile communications-based recording method are generally performed in a corresponding manner to the Internet-based recording method described above. Furthermore, the various methodologies described above are provided by way of illustration only and should not be construed to limit the invention. Those skilled in the art will readily recognize that various modifications and changes may be made to the claimed invention of the present application without departing from the true spirit and scope of the claimed invention. Accordingly, it is not intended that the claimed invention be limited, except as by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>With the continual increase of online transactions there has been an increasing need to improve the capabilities of online business related communication. One area where this is particularly true is in competitive sale exchanges, such as online auctions. The greater a seller's ability to showcase products, the more successful their online auctions sales are bound to become. With the number of online auctions growing daily, sellers are continuously looking for ways to improve the success of these auctions. Sellers are continuously looking for techniques or technology that will enable them to better explain what the products are that they are selling to potential buyers, as well as why those potential buyers should want the seller's products. Sellers also want to be able to effectively demonstrate how their products work. Additionally, sellers sometimes need to be able to demonstrate the authenticity of their products. Accordingly, people are continuously looking for ways to enhance their product listings and sales volume. Unfortunately, new systems and methods for increasing the capabilities of online business-related communications and transactions often result in increased intellectual complexity and/or increased computer system requirements. This tendency is undesirable because another main avenue for increasing the productively of online business-related communications and transactions is to increase the number of people who are participating in these online business-related transactions. Accordingly, it would be highly valuable if any new systems and methods for increasing the capabilities of online business-related communications and transactions also could be simple enough to help attract new users to the online business market and also not have extensive computer system requirements. Accordingly, there has been a long existing need for a system that improves the level of communication possible with respect to online business-related transactions. Further, there is a continuing need for an improved system and/or method that is simple, efficient, and does not have extensive computer system requirements. Accordingly, those skilled in the art have long recognized the need for a system and method that addresses these and other issues. | <SOH> SUMMARY OF THE INVENTION <EOH>Briefly, and in general terms, a preferred embodiment of the claimed invention resolves the above and other issues by providing an audio/video stream recording, storage, and delivery system. A preferred embodiment provides an Internet-based recording system that performs all audio and video stream recording over an Internet browser connection established between a user front end and a host back end. A host is this environment is generally defined as a company that is utilizing an audio/video stream recording, storage, and delivery system of the claimed invention. In one preferred embodiment, the system includes recording software, storage memory, a user interface, and a code generator. Preferably, the recording software, which is located on the host back end, processes and records audio and video material that originates from the user front end and is streamed to the host back end. The storage memory, which is located on the host back end, then stores the recorded audio and video material. In a preferred embodiment, the user interface to the audio/video stream recording, storage, and delivery system provides a user at the user front end with remote access to a virtual recording room. The user interface further enables the user to record audio and video material streamed from the user front end by activating the recording software residing on the host back end. Advantageously, this is accomplished without requiring recording functionality on the user front end. Preferably, the code generator produces code associated with the recorded audio and video material. The user interface is configured to facilitate easily copying and pasting the code to an additional location, such as an auction website. The code facilitates accessing the recorded audio and video material stored at the host back end from the additional location at which the code has been pasted. In this manner, activating the pasted code at the additional location provides access to the recorded audio and video material from the additional location while allowing the recorded audio and video material to remain stored at the host back end. Additionally, another preferred embodiment of the claimed invention is directed towards an Internet-based recording method that performs all audio and video stream recording over an Internet browser connection established between a user front end and a host back end. Preferably, the components required at the user front end include only a microphone, a camera, and access to the Internet browser. In one preferred embodiment, the method includes: (1) recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (2) storing the recorded audio and video material on the host back end; and (3) providing access to the recorded audio and video material. In accordance with one aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling the recorded audio and video material on the host back end to be reviewed at the user front end. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling recorded audio and video material on the host back end to be re-recorded from the user front end. In accordance with still another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes linking the recorded audio and video material stored at the host back end to a pointer that is located in at least one additional location, in response to input from the user front end. Accordingly, activating the pointer then provides access to the recorded audio and video material stored at the host back end. In one preferred embodiment, the pointer includes a hyperlink. In accordance with another aspect of the preferred embodiment, the step of recording and storing the audio and video material further includes producing hypertext markup language code that is associated with the recorded and stored audio and video material. However, in other preferred embodiments of the invention, other coding languages (such as DHTML and the like) are utilized. This code facilitates accessing the recorded and stored audio and video material. In accordance with yet another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes: enabling access to the recorded audio and video material stored at the host back end from an additional location by copying the hypertext markup language code produced at the host back end and pasting the hypertext markup language code to the additional location. In one preferred embodiment, the additional location is an auction website. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling recorded audio and video material on the host back end to be edited from the user front end. Preferably, recorded audio and video material includes a recorded audio portion and a recorded video portion. In one preferred embodiment, enabling recorded audio and video material on the host back end to be edited from the user front end includes, in response to input from the user front end, enabling audio material to be re-dubbed over the recorded audio portion of the recorded audio material while retaining the recorded video portion of the originally recorded audio and video material. In accordance with another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes, in response to input from the user front end, copying (or downloading) the recorded audio and video material stored at the host back end to at least one additional location. In accordance with still another aspect of the preferred embodiment, the step of providing access to the recorded audio and video material includes enabling additional audio material, video material, or audio and visual material to be attached to the recorded audio and video material stored on the host back end. In such a preferred embodiment, the additional audio material, video material, or audio and visual material originates from the user front end. Another preferred embodiment of the claimed invention is also directed towards an Internet-based recording method that performs all audio and video recording functions over an Internet browser connection established between a user front end and a host back end. In this additional preferred embodiment, the method includes: (1) recording audio and video material over the Internet browser connection, wherein audio and video material originates on the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (2) storing the recorded audio and video material on the host back end; (3) generating code associated with the recorded and stored audio and video material to facilitate accessing the recorded and stored audio and video material; and (4) enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio and video material from the additional location. In one preferred embodiment, the generated code is hypertext markup language that is associated with, and linked to, the recorded and stored audio and video material. In this manner, the associated code facilitates access to the recorded and stored audio and video material from the additional location. Yet another preferred embodiment of the claimed invention is directed towards a similar Internet-based recording method that performs all audio recording functions over an Internet browser connection established between a user front end and a host back end. In a preferred embodiment, the method includes: (1) uploading photographic still material to the host back end from the user front end; (2) recording audio material, over the Internet browser connection, to link the audio material with the photographic still material, wherein audio material originates from the user front end and is recorded on the host back end without requiring recording functionality on the user front end; (3) storing the recorded audio material and the linked photographic still material on the host back end; (4) generating code associated with the recorded audio material and the linked photographic still material to facilitate accessing the recorded audio material and the linked photographic still material; and (5) enabling the generated code to be copied and pasted to an additional location, wherein activating the generated code provides access to the recorded audio material and the linked photographic still material from the additional location. Still another preferred embodiment of the claimed invention is directed towards a Wi-Fi (Wireless Fidelity, i.e., generally referring to any type of IEEE 802.11 network) recording method that performs at least part of the audio and video recording functions over a Wi-Fi connection established between a user front end and a host back end. In such a preferred embodiment, the method includes recording audio and video material over a Wi-Fi connection using a personal digital assistant. The remainder of the Wi-Fi recording method is generally performed in a similar fashion to the Internet-based recording method described above. Finally, another preferred embodiment of the claimed invention is directed towards a wireless mobile communications-based recording method that performs all (or at least part) of the audio and video recording functions over a wireless mobile connection established between a user front end and a host back end. In such a preferred embodiment, the method includes recording audio and video material over a wireless mobile connection. The remainder of the wireless mobile communications-based recording method is generally performed in a similar fashion to the Internet-based recording method described above. Other features and advantages of the claimed invention of the present application will become apparent from the following detailed description, taken in conjunction with the achosting drawings, which illustrate by way of example, the features of the claimed invention. | 20040324 | 20151013 | 20050929 | 68807.0 | 14 | FOSSELMAN, JOEL W | REMOTELY ACCESSED VIRTUAL RECORDING ROOM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,809,042 | ACCEPTED | Tubing expansion | There is disclosed a tubing expansion device and a method of expanding tubing. In one embodiment, an expansion device (10) is disclosed which comprises at least one expansion member (14) adapted to expand a tubing (12) by inducing a hoop stress in the tubing (12), and at least one further expansion member (16) adapted to expand the tubing (12) by inducing a compressive yield of the tubing (12); and a method of expanding tubing (12) comprising the steps of expanding the tubing (12) at least in part by inducing a hoop stress in the tubing (12), and expanding the tubing (12) at least in part by inducing a compressive yield of the tubing (12). | 1. A tubing expansion device comprising: at least one expansion member adapted to expand a tubing by inducing a hoop stress in the tubing; and at least one further expansion member adapted to expand the tubing by inducing a compressive yield of the tubing. 2. A tubing expansion device as claimed in claim 1, wherein the expansion device is adapted to be rotated and translated through tubing to be expanded. 3. A tubing expansion device as claimed in claim 1, wherein the expansion device is adapted to be advanced through tubing to be expanded without rotation. 4. A tubing expansion device as claimed in claim 1, wherein the device is arranged such that expansion of the tubing to a desired final diameter is carried out by the compressive yield inducing expansion member. 5. A tubing expansion device as claimed in claim 1, wherein the device is arranged such that expansion of the tubing to a desired final diameter is carried out using the hoop stress inducing expansion member. 6. A tubing expansion device as claimed in claim 1, wherein the hoop stress and compressive yield inducing expansion members are axially spaced. 7. A tubing expansion device as claimed in claim 1, wherein the hoop stress and compressive yield inducing expansion members are circumferentially spaced. 8. A tubing expansion device as claimed in claim 1, wherein the hoop stress and compressive yield inducing expansion members are arranged according to at least one parameter of a tubing to be expanded. 9. A tubing expansion device as claimed in claim 8, wherein the parameter is selected from the group comprising: a pre-expansion diameter of the tubing; a pre-expansion wall thickness of the tubing; a desired post expansion diameter of the tubing; a desired post expansion wall thickness of the tubing; a pre-expansion strength of the tubing; Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength of the tubing; and an axial length of the tubing post-expansion. 10. A tubing expansion device as claimed in claim 1, wherein the expansion members are provided spaced alternately in an axial direction. 11. A tubing expansion device as claimed in claim 1, wherein the expansion members are provided spaced alternately in a circumferential direction. 12. A tubing expansion device as claimed in claim 1, wherein said hoop stress and compressive yield inducing expansion members are provided on respective separate portions coupled together to form the expansion device. 13. A tubing expansion device as claimed in claim 12, wherein the expansion device further comprises a hoop stress inducing expansion tool and a compressive yield inducing expansion tool, each carrying said respective hoop stress and compressive yield inducing expansion members. 14. A tubing expansion device as claimed in claim 12, wherein the portions are coupled together and restrained against relative rotation. 15. A tubing expansion device as claimed in claim 12, wherein at least one of said portions is rotatable relative to at least one other portion. 16. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member is adapted to contact the tubing over a majority of a circumference of the tubing. 17. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is adapted to contact the tubing over part of a circumference of the tubing. 18. A tubing expansion device as claimed in claim 17, wherein the compressive yield inducing expansion member is adapted to contact the tubing in a point contact. 19. A tubing expansion device as claimed in claim 17, wherein the compressive yield inducing expansion member is adapted to contact the tubing in a line contact. 20. A tubing expansion device as claimed in claim 1, comprising a plurality of hoop stress inducing expansion members. 21. A tubing expansion device as claimed in claim 20, wherein said hoop stress inducing expansion members describe progressively increasing expansion diameters in a direction along an axial length of the device. 22. A tubing expansion device as claimed in claim 1, comprising a plurality of compressive yield inducing expansion members. 23. A tubing expansion device as claimed in claim 22, wherein said compressive yield inducing expansion members are arranged to describe progressively increasing expansion diameters in a direction along an axial length of the device. 24. A tubing expansion device as claimed in claim 1, comprising a plurality of hoop stress inducing expansion portions each having at least one hoop stress inducing expansion member. 25. A tubing expansion device as claimed in claim 1, comprising a plurality of compressive yield inducing expansion portions each having at least one compressive yield inducing expansion member. 26. A tubing expansion device as claimed in claim 1, comprising a plurality of hoop stress inducing expansion portions each having at least one hoop stress inducing expansion member, and a plurality of compressive yield inducing expansion portions each having at least one compressive yield inducing expansion member, said hoop stress and compressive yield inducing expansion portions axially alternating along a length of the device. 27. A tubing expansion device as claimed in claim 1, comprising a plurality of hoop stress inducing expansion portions each having at least one hoop stress inducing expansion member, and a plurality of compressive yield inducing expansion portions each having at least one compressive yield inducing expansion member, wherein a plurality of said hoop stress inducing expansion portions are coupled together and joined to at least one compressive yield inducing expansion portion. 28. A tubing expansion device as claimed in claim 1, comprising a plurality of hoop stress inducing expansion portions each having at least one hoop stress inducing expansion member, and a plurality of compressive yield inducing expansion portions each having at least one compressive yield inducing expansion member, wherein a plurality of said compressive yield inducing expansion portions are coupled together and joined to at least one hoop stress inducing expansion portion. 29. A tubing expansion device as claimed in claim 1, comprising at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member provided on a single portion of the device. 30. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member comprises a fixed expansion member. 31. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member is fixed relative to a remainder of the device. 32. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member is formed integrally with a body of the expansion device. 33. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member is rotatable with respect to the tubing. 34. A tubing expansion device as claimed in claim 33, wherein the hoop stress inducing expansion member is rotatably mounted on a body of the device. 35. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member comprises a fixed diameter expansion member. 36. A tubing expansion device as claimed in claim 35, wherein the hoop stress inducing expansion member comprises an expansion cone. 37. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member comprises a compliant expansion member. 38. A tubing expansion device as claimed in claim 37, wherein the hoop stress inducing expansion member comprises a compliant cone. 39. A tubing expansion device as claimed in claim 1, comprising a hoop stress inducing expansion tool including a plurality of hoop stress inducing expansion rollers mounted for rotation about an axis substantially perpendicular to an axis of the tool. 40. A tubing expansion device as claimed in claim 1, comprising a cone with a plurality of hoop stress inducing expansion rollers rotatably mounted on the cone. 41. A tubing expansion device as claimed in claim 1, wherein the hoop stress inducing expansion member takes the form of a collapsible expansion cone which is movable between a collapse position and an expansion position, in the expansion position, the cone adapted for expanding the tubing. 42. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member comprises a rotary expansion member, which is rotatable about an expansion member axis. 43. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is provided as part of a compressive yield inducing expansion member module releasably coupled to a body of the device as a unit. 44. A tubing expansion device as claimed in claim 43, wherein the compressive yield inducing expansion member is rotatably mounted on a spindle. 45. A tubing expansion device as claimed in claim 44, wherein the spindle is cantilevered and extends from a body of the device. 46. A tubing expansion device as claimed in claim 44, wherein the spindle is pivotally coupled to the body. 47. A tubing expansion device as claimed in claim 44, wherein an axis of the spindle is disposed at an angle with respect to a main axis of the device. 48. A tubing expansion device as claimed in claim 1, comprising a bearing between the compressive yield inducing expansion member and a body of the device, and a sealed lubrication system for containing lubricant to facilitate rotation of the compressive yield inducing expansion member relative to the body. 49. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is radially moveably mounted with respect to a body of the device, for movement towards an expansion configuration describing an expansion diameter for expanding tubing to a predetermined diameter. 50. A tubing expansion device as claimed in claim 49, wherein the compressive yield inducing expansion member is lockable in the extended configuration. 51. A tubing expansion device as claimed in claim 49, wherein the compressive yield inducing expansion member is biased radially inwardly. 52. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is moveable in response to applied fluid pressure. 53. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is moveable in response to an applied mechanical force. 54. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is radially moveable relative to a body of the device in response to both: a) an applied mechanical force; and b) an applied fluid pressure force. 55. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is pivotally mounted with respect to a body of the device for movement towards an extended configuration. 56. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is adapted to generate a drive force on the tubing for at least partly translating the device with respect to the tubing. 57. A tubing expansion device as claimed in claim 56, wherein the drive force is generated on rotation of the expansion device. 58. A tubing expansion device as claimed in claim 56, wherein the expansion device is adapted to be translated through the tubing by a combination of an external axial force and the generated drive force. 59. A tubing expansion device as claimed in claim 56, wherein the expansion device is adapted to be translated through the tubing without an externally applied axial force. 60. A tubing expansion device as claimed in claim 56, wherein an axis of the compressive yield expansion member is skewed with respect to a body of the device. 61. A tubing expansion device as claimed in claim 56, wherein the device comprises a plurality of compressive yield inducing expansion members, and wherein the members are circumferentially spaced and helically oriented with respect to a body of the device. 62. A tubing expansion device as claimed in claim 56, wherein the compressive yield inducing expansion member includes a gripping surface for gripping the tubing to impart a drive force on the tubing. 63. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is adapted to expand the tubing by less than 50% of the total expansion of the tubing. 64. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is adapted to expand the tubing by less than 25% of the total expansion of the tubing. 65. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member is adapted to expand the tubing by less than 10% of the total expansion of the tubing. 66. A tubing expansion device as claimed in claim 1, wherein at least one of the hoop stress inducing and compressive yield inducing expansion members has an expansion member axis, and wherein said axis is non-parallel with respect to a main axis of the device. 67. A tubing expansion device as claimed in claim 1, wherein the compressive yield inducing expansion member comprises a rotary expansion member, which is rotable about an expansion member axis, and wherein said axis is non-parallel with respect to a main axis of the device. 68. A tubing expansion device as claimed in claim 67, wherein said expansion member axis converges with the tool main axis towards a leading end of the device. 69. A tubing expansion device as claimed in claim 67, wherein the compressive yield inducing expansion member is rotatably mounted on a spindle, and wherein the spindle is disposed non-parallel with respect to the device main axis. 70. A tubing expansion device as claimed in claim 67, wherein the compressive yield inducing expansion member includes a spindle which is rotatable relative to a body of the device, and wherein the spindle is disposed non-parallel with respect to the device main axis. 71. A method of expanding tubing, the method comprising the steps of: expanding the tubing at least in part by inducing a hoop stress in the tubing; and expanding the tubing at least in part by inducing a compressive yield of the tubing. 72. A method as claimed in claim 71, comprising providing an expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member. 73. A method as claimed in claim 71, comprising expanding the tubing to a first diameter by inducing one of a hoop stress in the tubing and a compressive yield of the tubing, and subsequently expanding the tubing to a second, greater diameter by the other one of inducing a hoop stress in the tubing and a compressive yield of the tubing. 74. A method as claimed in claim 73, comprising providing an expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member, and arranging said hoop stress and compressive yield inducing expansion members such that on translation of the tool through the tubing, expansion of the tubing to a first diameter is carried out using the hoop stress inducing expansion member, and expansion to a second, greater diameter is carried out using the compressive yield inducing expansion member. 75. A method as claimed in claim 73, comprising providing an expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member, and arranging said hoop stress and compressive yield inducing expansion members such that on translation of the tool through the tubing, expansion of the tubing to a first diameter is carried out using the compressive yield inducing expansion member, and expansion to a second, greater diameter is carried out using the hoop stress inducing expansion member. 76. A method as claimed in claim 74, comprising arranging the hoop stress inducing expansion member and the compressive yield inducing expansion member relative to each other according to at least one parameter of tubing to be expanded. 77. A method as claimed in claim 76 comprising selecting the parameter from the group comprising: a pre-expansion diameter of the tubing; a pre-expansion wall thickness of the tubing; a desired post-expansion diameter of the tubing; a desired post-expansion wall thickness of the tubing; a pre-expansion yield strength of the tubing; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength of the tubing; and an axial length of the tubing post-expansion. 78. A method as claimed in claim 71, comprising expanding the tubing without any change in axial length thereof. 79. A method as claimed in claim 71, comprising expanding the tubing by progressively increasing amounts to a desired final diameter. 80. A method as claimed in claim 71, comprising providing a plurality of expansion tool portions, at least one expansion tool portion carrying at least one hoop stress inducing expansion member and at least one other expansion tool portion carrying at least one compressive yield inducing expansion member. 81. A method as claimed in claim 80, comprising providing at least one of the expansion portions with a combination of hoop stress inducing and compressive yield inducing expansion members. 82. A method as claimed in claim 80, comprising determining at least one parameter of the tubing; and coupling the portions together in a desired axial arrangement selected according to the determined parameter. 83. A method as claimed in claim 82, comprising selecting the parameter from the group comprising: a pre-expansion diameter of the tubing; a pre-expansion wall thickness of the tubing; a desired post-expansion diameter of the tubing; a desired post-expansion wall thickness of the tubing; a pre-expansion yield strength of the tubing; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength of the tubing; and an axial length of the tubing post expansion. 84. A method as claimed in claim 71, comprising inducing a hoop stress in the tubing by bringing an expansion member into contact with a majority of a circumference of the tubing. 85. A method as claimed in claim 71, comprising inducing a compressive yield by bringing an expansion member into a point contact with the tubing, and rotating said expansion member around a circumference of the tubing. 86. A method as claimed in claim 71, comprising inducing a compressive yield by bringing an expansion member into a line contact with the tubing, and rotating said expansion member around a circumference of the tubing. 87. A method as claimed in claim 71, comprising rotating the expansion device to generate an axial drive force for at least partly translating the device through the tubing. 88. A method as claimed in claim 87, comprising providing at least one compressive yield inducing expansion member with an axis of said expansion member disposed non-parallel with respect to a main axis of the device. 89. A method as claimed in claim 87, comprising coupling a hoop stress inducing expansion cone to an expansion portion carrying said compressive yield inducing expansion member, and driving the cone through the tubing at least in part by said generated drive force. 90. A method of expanding tubing, the method comprising the steps of: determining at least one parameter of a tubing; providing a tubing expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member; arranging the at least one hoop stress inducing expansion member and the at least one compressive yield inducing expansion member relative to each other according to the at least one parameter; and translating the tubing expansion device through the tubing. 91. A method as claimed in claim 90, wherein the step of providing said expansion device comprises selecting the tubing expansion device from a group comprising a plurality of expansion devices each having a different arrangement of hoop stress and compressive yield inducing expansion members. 92. A method as claimed in claim 90, comprising selecting the parameter from the group comprising: a pre-expansion diameter of the tubing; a pre-expansion wall thickness of the tubing; a desired post-expansion diameter of the tubing; a desired post-expansion wall thickness of the tubing; a pre-expansion yield strength of the tubing; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength of the tubing; and an axial length of the tubing post-expansion. 93. A tubing expansion device comprising at least one fixed expansion member; and at least one rotary expansion member mounted for rotation with respect to a body of the tool. 94. A method of expanding tubing, the method comprising the steps of: providing a tubing expansion device having at least one fixed expansion member and at least one rotary expansion member mounted for rotation with respect to a body of the tool; and translating the tool through tubing to be expanded to expand the tubing in part by the fixed expansion member and in part by the rotary expansion member. | CROSS-REFERENCE TO RELATED APPLICATIONS This application claims benefit of Great Britain patent application serial number GB 0306774.1, filed Mar. 25, 2003, Great Britain patent application serial number GB 0312278.5, filed May 29, 2003, and Great Britain patent application number GB 0316050.4, filed Jul. 9, 2003 which are herein incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for use in tubing expansion and to methods of expanding tubing. In particular, but not exclusively, embodiments of the present invention relate to devices and methods for use in expanding tubing downhole. 2. Description of the Related Art In the oil and gas exploration and production industry, bores drilled to access subsurface hydrocarbon-bearing reservoirs are lined with tubing, known as casing and liner. Furthermore, strings of tubing may be located within the cased bore to, for example, carry production fluid to surface. Recently, there have been numerous proposals to use tubing which is expanded downhole, that is tubing of a first diameter is run into a bore and then expanded to a larger second diameter. This offers many advantages to the operator, primarily providing the ability to create lined bores which do not necessarily suffer a loss in internal diameter each time a string of tubing is located in the bore, beyond an existing section of tubing-lined bore. Early proposals for expanding tubing downhole featured the use of cones or mandrels, which are driven through the tubing in order to expand the tubing. Other proposals include the use of roller expanders, some of which feature radially-urged rollers. When tubing is expanded using a cone or mandrel, the expansion mode is different from when tubing is expanded using roller expanders. Typically, tubing expanded with a cone or mandrel tends to shorten in axial length whilst maintaining or suffering only a small reduction in wall thickness. Tubing expanded using roller expanders, however, tends to extend in axial length and experiences a reduction in wall thickness, caused by a wall thinning action. These two different types of expansion devices offer various advantages and disadvantages depending upon the particular circumstances in which the device is employed. Also, it is generally preferred to expand tubing in a top-down expansion procedure, as it is possible to recover the expansion device in the event that the tool becomes lodged in the tubing. However, when expanding tubing using an expansion cone or mandrel, it is conventional to employ a bottom-up expansion procedure. This is because it is necessary to apply a relatively large force on the cone from surface (by setting weight down on the cone), or to apply a relatively high pressure to the reverse face of the expansion cone (such as by supplying a pressurised fluid behind the cone), and it is not possible or safe to achieve the required loading or pressure on the cone in a top-down expansion procedure. This is particularly true for deviated (horizontal) wells and extended reach wells, where the forces required to expand tubing are, generally speaking, relatively high. It is amongst the objects of embodiments of the present invention to provide improved devices and methods for use in expanding tubing downhole. SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a tubing expansion device comprising: at least one expansion member adapted to expand a tubing by inducing a hoop stress in the tubing; and at least one further expansion member adapted to expand the tubing by inducing a compressive yield of the tubing. It will be understood that the hoop stress in tubing is the stress in the tubing wall acting circumferentially in a plane perpendicular to an axis of the tubing. Tubing expanded by induced hoop stress experiences a different expansion mode compared to tubing expanded by compressive yield whereby the tubing tends to axially contract in length. Tubing expanded by compressive yield, however, tends to axially extend in length and experiences a reduction in the tubing wall thickness. The invention thus allows the relative advantages of these different expansion modes to be combined in a single device. The expansion device may be adapted to be translated through tubing to be expanded, and may be adapted to be rotated. Alternatively, the expansion device may be adapted to be advanced through tubing to be expanded without rotation. Preferably, the hoop stress inducing expansion member and the compressive yield inducing expansion member are arranged such that expansion of the tubing to a desired final diameter is carried out by the compressive yield inducing expansion member. The applicant has found that tubing expanded by compressive yield demonstrates improved material properties, particularly crush resistance, when compared to tubing expanded by a hoop stress, as disclosed in the Applicant's corresponding UK patent application No.0216074.5, the disclosure of which is incorporated herein by way of reference. Alternatively, if desired or appropriate, expansion to a desired final diameter may be carried out using the hoop stress inducing expansion member. Preferably, the hoop stress and compressive yield inducing expansion members are axially spaced, that is, axially separated, and/or circumferentially spaced, that is, spaced around a perimeter or circumference of the expansion device. The expansion members may be relatively axially and/or rotationally arranged according to at least one parameter of a tubing to be expanded, which may be selected from the group comprising: a pre-expansion diameter and/or wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion (which depends upon factors including the tubing material); a desired post-expansion strength and degree of collapse or crush resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. This final parameter may depend upon factors including the likelihood of the tubing becoming differentially stuck. This can occur, for example, when there is a large differential pressure between high pressure fluid (such as drilling fluid) in a borehole surrounding the tubing, and a formation having a relatively low formation pressure, such as a particularly permeable formation. This can cause the tubing to become adhered or stuck to a wall of the borehole. Accordingly, by balancing the axial extension and contraction effects of the different expansion modes, the tubing can be expanded without any change in axial length. The expansion members may be provided spaced alternately in an axial and/or rotational direction, and may be provided on separate portions or bodies, or as parts of separate tools, coupled together to form the expansion device. The expansion device may thus further comprise a hoop stress inducing expansion portion and a compressive yield inducing expansion portion, each carrying respective hoop stress and compressive yield inducing expansion members. The device may therefore be modular in nature, allowing a tool including a desired axial arrangement of the expansion tool portions, and thus of the hoop stress and compressive yield inducing expansion members, to be provided, according to particular requirements of the expansion device and, in particular, depending upon one or more parameter of the tubing to be expanded, as discussed above. The portions or tools may be coupled together, and may be restrained against relative rotation. Alternatively, at least one of said portions or tools may be rotatable relative to at least one other portion or tool. Thus where the device is rotated and translated through tubing, at least one of said portions or tools may remain rotationally stationary relative to the tubing. The hoop stress inducing expansion member may be adapted to contact the tubing over a majority of a circumference or perimeter of the tubing. The compressive yield inducing expansion member may be adapted to contact the tubing over part of a circumference or perimeter of the tubing, and may contact the tubing in a point or line contact. The expansion device may comprise a plurality of hoop stress inducing expansion members. Said expansion members may describe progressively increasing expansion diameters in a direction along an axial length of the device, to expand the tubing by progressively increasing degrees to a desired final diameter. The expansion device may additionally or alternatively comprise a plurality of compressive yield inducing expansion members. The compressive yield inducing expansion members may be arranged for movement to expansion positions describing progressively increasing expansion diameters in a direction along an axial length of the device. This may similarly facilitate expansion of the tubing to a desired diameter in progressive, incremental steps. The expansion device may comprise a plurality of hoop stress and/or a plurality of compressive yield inducing expansion portions or tools, which may be axially alternating. Alternatively, a number of hoop stress inducing expansion portions may be coupled together and joined to one or more compressive yield inducing expansion portions, or vice versa, or indeed in any other suitable arrangement. In a further alternative, the expansion device may comprise at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member provided as a single tool, portion, body or part. The hoop stress inducing expansion member may comprise a fixed expansion member. The hoop stress inducing expansion member may be fixed by coupling or mounting the member with respect to a remainder of the device, for rotation with respect to the tubing. Alternatively, the hoop stress inducing expansion member may be rotatable with respect to the tubing and may, for example, be rotatably mounted on or to a body of the device, such as by a bearing, swivel or the like. Thus where the tool is rotated on translation through the tubing, the hoop stress inducing expansion member may remain rotationally stationary relative to the tubing, save for any rotation due to a reaction force imparted on the member by the tubing. The hoop stress inducing expansion member may comprise a fixed diameter expansion member, such as a cone or mandrel, but may alternatively comprise a shoulder, arm, finger or the like. The expansion member may be formed integrally with or provided on or coupled to a body of the expansion device. Alternatively, the hoop stress inducing member may comprise a compliant expansion member such as a compliant cone, mandrel or the like, such as that disclosed in the applicant's International patent application no. PCT/GB2002/005387, the disclosure of which is incorporated herein by way of reference. It will be understood that a compliant expansion member is capable of inward deflection, for example, in the event that a restriction is encountered, such as an area of tubing which cannot be expanded. The device may further comprise a hoop stress inducing expansion tool, portion or body including a plurality of hoop stress inducing members, which may take the form of expansion rollers mounted for rotation about an axis substantially perpendicular to an axis of the tool, as disclosed in PCT/GB2002/005387. The expansion tool or portion may alternatively comprise a tapered expansion cone or mandrel with a plurality of rotary expansion members, such as rollers, rotatably mounted on the tapered cone, as disclosed in the applicant's International patent publication. no. WO 00/37766, the disclosure of which is also incorporated herein by way of reference. The hoop stress inducing expansion member may take the form of a collapsible expansion cone, mandrel or the like, which may be movable between a collapsed and an expansion position, in the expansion position, the cone adapted for expanding the tubing. The compressive yield inducing expansion member may comprise a rotary expansion member and may be rotatable with respect to the tubing. Preferably, the compressive yield inducing expansion member is rotatable relative to a body of the device about an expansion member axis. The expansion device may be adapted to generate a drive force for translating the device with respect to or through the tubing. This may facilitate expansion of the tubing in a top-down procedure when, in an embodiment of the invention, using an expansion cone, mandrel or the like as the hoop stress inducing expansion member. The drive force may be generated on rotation of the expansion device. The compressive yield inducing expansion member may be adapted to generate a drive force on the tubing, the generated drive force serving for at least partly translating the device with respect to the tubing. The expansion device may be adapted to be translated through the tubing by a combination of an external axial force, which may be applied through a tubing string coupled to the device and the generated drive force, or the generated drive force may be sufficient to translate the device through the tubing without an externally applied axial force. An axis of the compressive yield expansion member may be skewed with respect to a body of the device. This may generate an axial drive force on rotation of the device. Where the device comprises a plurality of said expansion members, the members may be rotationally spaced and helically oriented with respect to a body of the device, as disclosed in WO 00/37766. The compressive yield inducing expansion member may be adapted to expand the tubing by a relatively small amount compared to the expansion generated by the hoop stress inducing expansion member. For example, the compressive yield inducing expansion member may expand the tubing by less than 50%, typically less than 25% and preferably by less than 10% of the total expansion achieved using the expansion device. The compressive yield inducing expansion member may include a gripping surface for gripping the tubing to impart a drive force on the tubing, and may, for example, have a knurled or toothed gripping surface, or a combination thereof. The expansion device may be adapted to be rotated from surface by rotation of a tubing string coupled to the device, or by a downhole motor such as a turbine, positive displacement motor (PDM), electrical motor or the like. The compressive yield inducing expansion member may be provided as part of a compressive yield inducing expansion member module releasably coupled to a body of the device as a unit, and the compressive yield inducing expansion member may be rotatably mounted on a spindle. The spindle may comprise a cantilevered spindle extending from a body of the device. The expansion device may comprise a bearing between the compressive yield inducing expansion member and a body of the device, and a sealed lubrication system for containing lubricant to facilitate rotation of the compressive yield inducing expansion member relative to the body. The spindle may be pivotally coupled to the body. An axis of the spindle may be disposed at an angle with respect to a main axis of the tool. The compressive yield inducing expansion member may be radially moveably mounted with respect to a body of the device, for movement towards an expansion configuration describing an expansion diameter for expanding tubing to a predetermined diameter. The expansion member may be lockable in the extended configuration. The expansion member may additionally or alternatively be biased radially inwardly. Thus in the absence of an expansion force exerted on the compressive yield inducing expansion member, the expansion member may be biased towards a retracted configuration. The expansion member may be moveable in response to both: a) an applied mechanical force; and b) an applied fluid pressure force. The expansion member may be pivotally mounted with respect to a body of the device for movement towards the extended configuration. The above features are disclosed in the Applicant's UK patent application No. 0220933.6, the disclosure of which is incorporated herein by way of reference. According to a second aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: expanding the tubing at least in part by inducing a hoop stress in the tubing; and expanding the tubing at least in part by inducing a compressive yield of the tubing. The method may comprise expanding the tubing at least in part by rotary expansion, but the tubing may alternatively be expanded without rotation. The method may comprise providing an expansion device comprising a hoop stress inducing expansion member and a compressive yield inducing expansion member. The method may comprise expanding the tubing to a first diameter by inducing one of a hoop stress in the tubing and a compressive yield of the tubing, and subsequently expanding the tubing to a second, greater diameter by the other one of inducing a hoop stress in the tubing and a compressive yield of the tubing. For example, the method may comprise providing at least one expansion member adapted to expand a tubing by inducing a hoop stress in the tubing; and at least one further expansion member adapted to expand the tubing by inducing a compressive yield of the tubing, and arranging said expansion members such that on translation of the tool through the tubing, expansion of the tubing to a first diameter is carried out using the hoop stress inducing expansion member, and expansion to a second, greater diameter is carried out using the compressive yield inducing expansion member, or vice versa. The method may comprise arranging a hoop stress inducing expansion member and a compressive yield inducing expansion member relative to each other according to at least one parameter of tubing to be expanded, and the parameter may be selected from the group comprising: a pre-expansion diameter and/or wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength and degree of collapse resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. In one embodiment of the invention, the method may comprise expanding the tubing without any or with negligible change in axial length of the tubing. The tubing may be expanded by progressively increasing amounts to a desired final diameter, by providing a plurality of expansion members. The method may comprise providing a plurality of expansion tool portions, one expansion tool portion carrying at least one hoop stress inducing expansion member and another expansion tool portion carrying at least one compressive yield inducing expansion member. The expansion tool portions may be provided with a combination of hoop stress inducing compressive yield inducing expansion members. The method may comprise providing a hoop stress inducing expansion tool or portion and a compressive yield inducing expansion tool or portion, each having a respective expansion member, selecting a desired axial arrangement of the expansion tools or portions and coupling the tools or portions together according to the selected arrangement. The arrangement may be selected according to said at least one parameter defined above. The method may comprise inducing a hoop stress in the tubing by bringing an expansion member into contact with a majority of a circumference or perimeter of the tubing. The method may comprise inducing a compressive yield by bringing an expansion member into a line or point contact with the tubing, and rotating said expansion member around the circumference or perimeter of the tubing. The method may further comprise rotating the expansion device to generate a drive force for at least partly translating the device through the tubing. In an embodiment of the invention, the method comprises providing a compressive yield inducing expansion tool as disclosed in WO 00/37766, and with an axis of the compressive yield inducing expansion member at an angle with respect to a main axis of the device, and rotating said tool to generate the drive force. A hoop stress inducing expansion member such as a cone, mandrel or the like may be coupled to and thus driven by said expansion tool. At least one of the hoop stress inducing and compressive yield inducing expansion members may have an expansion member axis, the axis disposed at an angle with respect to a main axis of the device. Where the compressive yield inducing expansion member comprises a rotary expansion member, said expansion member may be rotatable about an expansion member axis, said axis disposed at an angle with respect to a main axis of the device. The expansion member axis may converge with the tool main axis towards a leading end of the device. The compressive yield inducing expansion member may be rotatably mounted on a spindle, which may be disposed at an angle with respect to the device main axis, of the expansion member may include a spindle which is rotatable relative to a body of the device, the spindle disposed at an angle with respect to the device main axis. According to a third aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: determining at least one parameter of a tubing; providing a tubing expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member mounted for rotation with respect to a body of the tool, and with said hoop stress inducing expansion member and said compressive yield inducing expansion member provided in a desired arrangement relative to each other selected depending upon said parameter; and translating the tubing expansion device through the tubing. The step of providing said expansion device may comprise selecting the tubing expansion device from a group comprising a plurality of expansion devices each having a different arrangement of said hoop stress and compressive yield inducing expansion members. Thus an expansion device may be selected which is most appropriate for expanding the tubing, depending upon said determined parameter. Alternatively, the step of providing said expansion device may comprise assembling an expansion device with said hoop stress and compressive yield inducing expansion members provided in a desired arrangement selected depending upon said determined parameter. The parameter may be selected from the group comprising a pre-expansion diameter and wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength and degree of collapse resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. According to a fourth aspect of the present invention, there is provided a tubing expansion device comprising at least one fixed expansion member; and at least one rotary expansion member mounted for rotation with respect to a body of the tool. According to a fifth aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: providing a tubing expansion device having at least one fixed expansion member and at least one rotary expansion member mounted for rotation with respect to a body of the tool; and translating the tool through tubing to be expanded to expand the tubing in part by the fixed expansion member and in part by the rotary expansion member. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 is a schematic view of a tubing expansion device in accordance with an embodiment of the present invention; FIG. 2 is a view of the tubing expansion device of FIG. 1 shown in use; FIGS. 3, 4, 5, 5A, 5B, 5C, 5D and 5E are schematic views of tubing expansion devices in accordance with alternative embodiments of the present invention; FIG. 6 is a view of a view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with an embodiment of the present invention; FIG. 7 is a longitudinal sectional view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with an alternative embodiment of the present invention, the tool shown in a deactivated configuration and located in tubing to be expanded; FIG. 8 is a view of the expansion tool of FIG. 7, drawn to a larger scale and shown in an expanded configuration during expansion of the tubing; FIG. 9 is a view of the expansion tool of FIG. 7, shown in the deactivated configuration in alternative tubing to be expanded; FIG. 10 is a view of the expansion tool of FIG. 9 in the expanded configuration, drawn to a larger scale and shown during expansion of the tubing; FIGS. 11 is a longitudinal sectional view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention, the tool shown in a deactivated configuration; FIG. 12 is a view of the expansion tool of FIG. 11, drawn to a larger scale and shown in an expanded configuration; FIG. 13 is a longitudinal sectional view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention, the tool shown in a deactivated configuration; FIG. 14 is a schematic, bottom view of the expansion tool of FIG. 13 showing expansion members of the tool in both the de-activated and the expanded configurations; FIG. 15 is a view of the tubing expansion tool of FIG. 13, drawn to a larger scale and shown in an expanded configuration; FIG. 16 is a sectional view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention; FIG. 17 is an end view of the tool of FIG. 16, showing the diameters described by the expansion members; FIG. 18 is an enlarged sectional view showing details of the bearing arrangement between an expansion member and a spindle of the tool of FIG. 16; FIG. 19 is a sectional view of an alternative expansion member for the tool of FIG. 16; FIG. 20 is a perspective view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention, with three of the five expansion members removed; FIG. 21 is a front view of the tool of FIG. 20; FIG. 22 is a sectional view on line 7-7 of FIG. 21; FIG. 23 is an enlarged view of a portion of FIG. 22; FIG. 24 is an end view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention; FIG. 25 is a sectional view on line 10-10 of FIG. 24; FIG. 26 is a side view showing one half of the tool of FIG. 24; FIG. 27 is a sectional view of an expansion tool forming part of any one of the expansion devices of FIGS. 1 to 5E, in accordance with a further alternative embodiment of the present invention; FIGS. 28 and 29 are top and bottom views of the expansion tool of FIG. 27, respectively; and FIG. 30 is a perspective view of the expansion tool of FIG. 27. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning firstly to FIG. 1, there is shown a schematic view of a tubing expansion device in accordance with an embodiment of the present invention, the device indicated generally by reference numeral 10. The expansion device 10 is shown in FIG. 2 in use, during expansion of tubing in the form of an expandable liner 12. The expansion device 10 comprises at least one hoop stress inducing expansion member, in this embodiment, a fixed expansion member in the form of an expansion cone or mandrel 14 and at least one compressive yield inducing expansion member, in this embodiment, a rotary expansion member in the form of rotary expansion cone 16. The cone 16 is mounted for rotation with respect to a body 18 of the expansion device 10. The expansion device 10 is translated through the liner 12 to expand the liner to a greater diameter and, as will be described below, this expansion is achieved in part by the mandrel 14 and in part by the rotary expansion cone 16. In more detail, the expansion device 10 comprises two expansion tool portions in the form of a hoop stress inducing expansion tool portion 20 and a compressive yield inducing expansion tool portion 22. The expansion tool portion 20 includes a body 24 which is coupled to a string of tubing 26 for running the expansion device 10 into a borehole 28, the body 24 coupled to the tubing string 26 by, for example, a conventional pin and box type connection 30. The expansion cone 14 extends between the body 24 and the expansion tool portion 22, which may comprise one of a number of types of rotary expansion tools, as will be described below. In FIGS. 1 and 2, the compressive yield inducing expansion tool portion 22 comprises a rotary expansion tool having three rotary expansion cones 16, which are activated in response to applied fluid pressure to move from a retracted configuration (FIG. 1) to an extended, expansion configuration (FIG. 2), for expanding the liner 12. Considering FIG. 2 in more detail, the expansion device 10 is shown run into a casing 32 previously located in the borehole 28 and cemented at 34, in a conventional fashion. The expandable liner 12 has been located within the casing 32 suspended, for example, through a temporary connection to the expansion device 10. The expansion device 10 is shown in FIG. 2 following activation and translation of the device part way through the liner 12. The device 10 is activated by supplying pressurized fluid to the device, to urge the rotary expansion cones 16 outwardly, and is rotated during translation through the liner 12. This causes an initial partial expansion of the liner 12 to a first diameter d1, as indicated by the area 36 in FIG. 2. The expansion device 10 is translated through the liner 12 in a top-down expansion procedure, thus following initial expansion to the diameter d1, the liner 12 is then expanded to a greater diameter d2 by the expansion cone 14. This is achieved by exerting a relatively large axial force on the device 10, for example, by setting weight down upon the expansion device 10 from surface through the tubing string 26. This process is continued until the liner 12 has been expanded over a desired length, and the expansion device 10 is then deactivated and recovered to surface. The liner 12 may act as a liner extending from a shoe of the casing 32 (the lowermost casing section), for gaining access to a hydrocarbon bearing formation. However, it will be understood that the tubing 12 may equally take the form of a straddle/patch or other solid tubing, or a sand exclusion based tubing assembly such as the applicant's ESS (Trademark) sandscreen, of the type disclosed in International Patent Publication No WO97/17524. Turning now to FIG. 3, there is shown a view of a tubing expansion device in accordance with an alternative embodiment of the present invention, the device indicated generally by reference numeral 110. Like components of the expansion device 110 with the device 10 of FIGS. 1 and 2 share the same reference numerals, incremented by 100. For brevity, only the differences between the devices 110 and 10 will be described herein in detail. The expansion device 110 includes a hoop stress inducing expansion tool portion 120 comprising three separate expansion mandrels 114, 114′, 114″ which are of progressively increasing maximum external diameter in a direction along a main axis 37 of the device away from a nose 38 of the tool. In use and during translation of the expansion device 110 through tubing, such as the liner 12 of FIG. 2, expansion of the liner out to a final diameter (such as the diameter d2) is achieved progressively, each expansion cone 114, 114′, 114″ providing a small increase in the diameter of the tubing. FIG. 4 is a view of a tubing expansion device in accordance with a further alternative embodiment of the present invention, the device indicated generally by reference numeral 210. Like components of the expansion device 210 with the device 10 of FIGS. 1 and 2 share the same reference numerals, incremented by 200. For brevity, only the differences between the devices 210 and 10 will be described herein in detail. The expansion device 210 includes two compressive yield inducing expansion tool portions 222, 222′ which are axially spaced along the expansion device 210, and a hoop stress inducing expansion tool portion 220 comprising expansion cone 214, which extends between the rotary portions 222 and 222′. The expansion tool portion 222′ includes three rotary expansion cones 216′ (one shown in FIG. 4) which describe a larger expansion diameter than the cones 216 of the expansion tool portion 222. Translation of the expansion device 210 through tubing such as the liner 12 of FIG. 2 provides a progressive increase in diameter of the tubing out to a maximum diameter determined by the rotary expansion cones 216′. The arrangement of the expansion device 210 is such that final expansion of the tubing is by the expansion cones 216′, offering advantages over fixed diameter mandrels or cones. This is the applicant has been found that mechanical properties of tubing expanded using a rotary expansion tool, such as the expansion tool portion 222′, exhibit different characteristics, such as improved post expansion strength and work hardening characteristics, compared to tubing expanded using cones or mandrels. Turning now to FIG. 5, there is shown a tubing expansion device in accordance with a yet further alternative embodiment of the present invention, the device indicated generally by reference numeral 310. Like components of the expansion device 310 with the device 10 of FIGS. 1 and 2 share the same reference numerals, incremented by 300. For brevity, only the differences between the devices 310 and 10 will be described herein in detail. The expansion device 310 includes a hoop stress inducing expansion portion 320 comprising a mandrel 314 at a leading end 338 of the device, for expanding tubing such as the liner 12 to a first diameter. The device also includes a compressive yield inducing expansion tool portion 322, axially spaced from mandrel 314, and comprising rotary expansion cones 316, for expanding the liner to a second greater diameter. Turning now to FIGS. 5A and 5B, there are shown tubing expansion devices in accordance with yet further alternative embodiments of the present invention, the devices indicated generally by reference numerals 410 and 510, respectively. Like components of the expansion devices 410 and 510 with the device 10 of FIGS. 1 and 2 shares the same reference numerals, incremented by 400 and 500, respectively. For brevity, only the differences between the devices 410/510 and 10 will be described herein in detail. FIG. 5A is a schematic view of the expansion device 410, which includes a hoop stress inducing expansion tool portion 420 having an expansion cone 414, and a compressive yield inducing expansion tool 422 having a plurality of rotary expansion cones 416. The rotary expansion cones 416 are mounted at a leading end of the expansion cone 414 for carrying out an initial expansion of tubing such as the liner 12, followed by expansion to a desired final diameter by the expansion cone 414. The expansion device of FIG. 5B is similar to the device 410 of FIG. 5A, except the device 510 includes a hoop stress inducing expansion tool portion 520 having an expansion cone 514 at a leading end of the device, with a compressive yield inducing expansion tool 522 having a plurality of rotary expansion cones 516 at a trailing end of the expansion cone 514, for expanding the tubing to a desired final diameter. Turning now to FIG. 5C, there is shown an expansion device 610 in accordance with a further alternative embodiment of the present invention. The expansion device 610 is similar to the expansion device 10 of FIG. 1, and like components share the same reference numerals, incremented by 600. In a similar fashion to the device 10, the device 610 includes a compressive yield inducing expansion tool 622 of a type disclosed in WO 00/37766, the expansion tool 622 acting as a tractor. In the illustrated embodiment, the rotary expansion rollers 616 are mounted in the tool body 618 with their axes skewed with respect to a main axis of the device 610, in a helical configuration. An expansion cone 614 is coupled to the expansion tool 622 optionally via a swivel 625 and, on activation and rotation of the expansion tool 622 within tubing such as the liner 12, the expansion rollers 616 generate a drive force on the liner 12 to pull the expansion cone 614 through the liner 12. The swivel 625 allows the expansion cone 614 to be advanced through the liner 12 with little or no rotation. The rollers 616 cause a partial expansion of the liner 12, however, the primary expansion is by the expansion cone 614. The rollers 616 optionally have knurled, toothed or otherwise shaped or textured gripping surfaces 46, to improve grip with the liner 12. The expansion device 610 is rotated either from surface through a string of tubing (not shown) coupled to the compressive yield inducing expansion tool 622, or by a downhole motor such as a turbine, PDM or electrical motor. The expansion device 610 thus acts as a tractor for the expansion cone 614 and allows tubing such as the liner 12 to be expanded in a top-down expansion procedure utilizing an expansion cone or mandrel, overcoming problems associated with prior proposals. In particular, as noted above, solid cone expansion forces are high, and expansions are typically performed from the bottom up because it is not possible (or safe) to achieve the required set down weight to go from the top down in most applications. However, by utilizing the expansion tool 622 as a tractor and thus by applying the tractor load as close to the cone 614 as possible, this reduces the surface loads needed to complete cone expansion. Turning now to FIG. 5D, there is shown an expansion device 710 in accordance with a further alternative embodiment of the present invention, shown in partial longitudinal cross-section. The expansion device 710 is essentially similar to the expansion device 310 of FIG. 5, except the device 710 includes a hoop stress inducing expansion tool having an expansion cone 714 rotatably mounted on a body 718 of the device 710 by a bearing (not shown). This facilitates translation of the expansion device 710 through tubing to be expanded, such as the liner 12, with little or no rotation of the cone 714 relative to the liner 12. Turning now to FIG. 5E, there is shown an expansion device 810 in accordance with a further alternative embodiment of the present invention. The expansion device 810 is similar to the expansion device 10 of FIG. 1 and like components with the expansion device 10 share the same reference numerals, incremented by 800. The expansion device 810 includes a hoop stress inducing expansion tool 820 having a tapered support mandrel 814 with two sets of expansion rollers 48, 48′ mounted with their axes perpendicular to a main axis of the device 810. The sets of expansion rollers 48, 48′ describe progressively increasing expansion diameters and may be compliant. The hoop stress inducing expansion tool 820 is connected via a swivel 50 to a compressive yield inducing expansion tool 722, and on activation of the device 810 and translation through the liner 12, there is little or no rotation of the cone 814 relative to the liner 12. As discussed above, expansion of tubing by inducing a hoop stress in the tubing using a cone or mandrel tends to cause an axial contraction in the length of the tubing, whilst expansion by inducing a compressive yield using rotary expansion tools tend to thin the wall of tubing and cause an axial extension. Thus, by providing a combination of hoop stress and compressive yield inducing expansion members in the expansion devices 10 to 810 of FIGS. 1 to 5E, it is possible to combine these expansion modes to achieve expansion of the liner 12 without causing extension or contraction of the liner. Also, if desired, a more controllable extension or contraction of the liner can be achieved by balancing the effects of the hoop stress and compressive yield inducing expansion members. In a further alternative embodiment not illustrated herein, an expansion device may be provided combining the theories of any of FIGS. 1 to 5E. For example, the expansion device 110 of FIG. 3 may comprise a plurality of rotary expansion tool portions 122, which may be provided in series or axially spaced between expansion cones such as the cones 114, 114′ and 114″. Alternatively, a device may be provided comprising any desired configuration or pattern of hoop stress and compressive yield inducing expansion cones, which may be spaced axially and/or rotationally around a body of the device. Furthermore, the particular arrangement or configuration of the hoop stress and compressive yield inducing expansion cones may be selected according to one or more determined parameters of the tubing to be expanded. These parameters may include the diameter and wall thickness of the tubing to be expanded; the initial yield strength of the tubing to be expanded; the Young's Modulus of the tubing material; the anticipated work hardening experienced by the tubing during expansion (which depends upon factors including properties of the material from which the tubing is formed); the desired end result in terms of the desired final strength and collapse resistance of the tubing; and the desired final length of the tubing, which depends upon the particular combination of hoop stress and compressive yield inducing expansion members used, as described above. This final parameter may be of particular interest where it is desired to avoid differential sticking of tubing, such as in an open hole environment. This is because the forces required to overcome differential sticking can cause problems with conventional expansion devices, such as failure of connections between sections of liner tubing. Turning now generally to FIGS. 6 to 36, there are shown various views of tubing expansion tools incorporating rotary expansion members, of types suitable for forming the rotary expansion tool portion 22 to 822 of any one of FIGS. 1 to 5E, respectively. Turning initially to FIG. 6, there is shown a longitudinal half-sectional view of a rotary expansion tool 22a, which takes the form of the applicant's commercially available rotary expansion tool, manufactured according to the principles of International patent publication No. WO 0/37766, the disclosure of which is incorporated herein by way of reference. Each rotary expansion cone 16a is rotatably mounted on a spindle 40a, which is in turn mounted on a piston 42a for movement between a retracted position shown in the left half of FIG. 6 and an extended, expansion position, shown in the right half of FIG. 6. The expansion tool 22a includes three such rotary expansion cones 16a spaced around the circumference of the tool body 18a. Turning now to FIG. 7, there is shown a longitudinal sectional view of an alternative tubing expansion tool 22b. The tool 22b is shown located in a liner 12b which is to be diametrically expanded. The expansion tool 22b is shown in FIG. 7 in a de-activated configuration. The expansion tool 22b comprises a hollow body 14b and four expansion members 16b, each radially moveably mounted on the body 14b, for movement towards an extended configuration describing an expansion diameter, as shown in FIG. 8. Each expansion member 16b includes an oval section expansion roller 18b mounted on a piston 20b, which is radially moveable in slots 22b in a tapered lower end 24b of the body 14b. Alternatively, the roller 18b is mounted in a body or housing pivotably mounted to the tool body 14b, for example, by a pivot such as the pivot 25b shown in the drawings. A hollow activating mandrel 26b is mounted in the body 14b for urging the rollers 18b to the extended configuration of FIG. 8. The mandrel 26b is moveable between a deactivating position shown in FIG. 7 and an activating position shown in FIG. 8, in response to either an applied mechanical force, an applied fluid pressure force or a combination of the two. A lower end 52b of the mandrel 26b is truncated cone-shaped, and defines a cam surface 54b for urging the rollers 18b to the extended configuration, as will be described below. The expansion tool 22b also includes a locking assembly 35b comprising a snap ring 27b located in a groove 29b in the mandrel 26b, for locking the rollers 18b in the extended configuration of FIG. 8. An upper end 28b of the mandrel 26b is coupled to a connecting sub 30b which allows a mechanical force to be exerted on the mandrel 26b to move the mandrel between the deactivating and activating positions. The connecting sub 30b is in-turn coupled to, for example, the mandrel 14 of the tool 10 (FIG. 1), and the sub 30b is axially moveable relative to the body 14. The tool 10 also includes a biasing member comprising a spring 36b, which biases the mandrel 26b towards the deactivating position of FIG. 7. In the deactivating position, the mandrel 26b de-supports the rollers 18b, allowing the rollers to be moved radially inwardly, towards the retracted position of FIG. 7. The biasing spring 36b is located between a shoulder 38b in the body 14b and a shoulder 40b of the connecting sub 30b. As will be described below, when the force on the mandrel 26b is removed or reduced, the spring 36b urges the sub 30b and mandrel 26b towards the deactivating position of FIG. 7, to de-support the rollers 18b. The tool body 14b includes an annular guide ring 42b which guides the mandrel 26b and a cylinder 44b are defined by an annular floating piston 46b mounted between the mandrel 26b and the body 14b. The mandrel 26b includes a number of ports 48b extending through the wall of the mandrel which allow fluid communication between a central bore 50b of the tool 22b and the cylinder 44b. Seals (not shown) are provided between the piston 46b and a shoulder 37b of the mandrel 26b such that the piston defines an upper piston area 29b and a smaller, lower piston area 31b, and further seals 58b, 60b are provided above and below the cylinder 44b. The seals 58b, 60b ensure that pressure is applied to the upper piston area 29b and that there is no leakage into the chamber of spring 36b, or past the piston 46b. Also, a flow restriction nozzle 33b is provided at the lower end of the mandrel 26b. As will be described below, both the differential piston area and the nozzle 33b allow movement of the mandrel 26b by application of fluid pressure, to urge the rollers 18b to the extended configuration. Flow ports 62b in the cone 52b allow flow of cooling fluid to the rollers 18b during expansion of the liner 12b. A method of operation of the expansion tool 22b will now be described, with reference to FIGS. 7 and 8. In a top-down expansion procedure, the tool 22b is run into a well borehole on coiled tubing and into the liner 12b. When the tool 22b has been located at the top of the liner 12b, fluid is circulated through the bore 50b of the tool, exiting through the nozzle 33b. The nozzle 33b restricts fluid flow and increases the back-pressure of fluid in the bore 50b, pressurizing fluid in the cylinder 44b relative to the fluid acting on the lower piston area 31b. The combination of the back-pressure of the fluid in the cylinder 44b and the differential piston area urges the piston 46b downwardly, carrying the mandrel 26b downwardly to the activating position of FIG. 8. During this movement, the cam surface 54b of the mandrel cone 52b abuts the roller pistons 20b, urging the pistons radially outwardly in their slots 23b, to the extended configuration of FIG. 8. At the same time, the tool 22b is rotated by an appropriate downhole motor, or from surface and the rollers 18b are progressively moved outwardly to describe an expansion diameter greater than the unexpanded internal diameter of the tubing 12b. When the mandrel 26b has moved fully downwardly, the snap ring 27b locks out against the guide ring 42b, to lock the mandrel 26b against return movement to the deactivating position of FIG. 1. The mandrel 26b is thus locked in the activating position, and maintains the rollers 18b in the extended configuration of FIG. 8. The rotating expansion tool 22b is then translated axially through the tubing 12b, and the rollers 18b diametrically expand the liner 12b to a greater internal diameter, as shown in FIG. 8. By verifying that the snap ring 27b has locked out to restrain the mandrel 26b in the activating configuration, this indicates to the operator that the rollers 18 were correctly located in the extended configuration during the expansion procedure. Accordingly, this provides an indication that the tubing 12b has been expanded to the desired, predetermined internal diameter described by the rollers 18b in the extended configuration. The snap ring 27b is then released and the mandrel 26b retracts to the deactivating position under the force of the spring 36b, thus de-supporting the rollers 18b. The rollers 18b can then be returned to the retracted configuration of FIG. 7. Turning now to FIGS. 9 and 10, an alternative method of operation of the tool 22b will be described. FIG. 9 shows the tool 22b located in borehole casing 32b, in the deactivated position. The tool 22b has been run into the casing 32b on a string together with expandable bore-lining tubing in the form of an expandable liner 66b. An upper end of the liner 66b is shown in FIG. 9, and is located overlapping the casing 32b, with a seal sleeve 68b provided on an outer surface of the liner 66b, for sealing between the casing 32b and the liner 66b. When the liner 66b has been located in the desired position, the tool 22b is set down on the upper end of the liner 66b and weight is applied to the mandrel 26b, through the connecting sub 30b. This moves the mandrel 26b downwardly, forcing the rollers 18b outwardly to the expanded configuration, and the snap ring 27b locks the mandrel in the activating position and thus the rollers 18b in the extended configuration. The tool 22b is then rotated and advanced axially through the liner 66b, diametrically expanding the liner into contact with the casing 32b as shown in FIG. 10 (in combination with a mandrel, as described above). The tool 22b is advanced through the liner 66b to a desired depth, and then recovered to surface, as described above. The liner 66b is thus hung from the casing 32b and sealed relative to the casing by the seal sleeve 68b. Turning now to FIG. 11 there is shown a further alternative tubing expansion tool 22c. Like components of the tool 22c with the tool 22b of FIG. 7 share the same reference numerals incremented by 100. For ease of reference, only the significant differences between the structure of the tool 22c with respect to the tool 22b will be described herein. The tool 22c includes three expansion member assemblies 116c, each comprising expansion arms 70c coupled to the tool body 114c by pivots 125c and an expansion ball 72c rotatably mounted to the arm 70c for expanding tubing. The arms 70c are spaced 1200 apart and are moveable about the pivots 125c between the de-activated configuration of FIG. 11 and the expanded configuration of FIG. 12 in the same fashion as the tool 22b. The mandrel 126c includes a cylindrical lower end 124c and each arm 70c includes an inner surface 156c which is recessed (not shown) to define a cam surface which abuts the mandrel lower end 124c. As the mandrel 126c descends, the mandrel urges the arms 70c, and thus the expansion balls 72c, outwardly to the expanded configuration of FIG. 12. Pivotably mounting the arms 70c on the body 114c in this fashion allows a high expansion ratio of the tubing as there is a relatively large movement of the expansion balls 72c between the de-activated and expanded configurations. Turning now to FIG. 13, there is shown a yet further alternative tubing expansion tool 22d. This view of the tool 22d corresponds to a section along line A-A of FIG. 14. It will be understood that the view of the tool 22c shown in FIG. 11 is sectioned in a similar fashion. Like components of the tool 22d with the tool 22b of FIG. 7 share the same reference numbers incremented by 200. Again, only the main differences between the tool 22d and the tool 22b will be described herein. The tool 22d includes three expansion members 216d spaced 1200 apart and including expansion arms 270d pivotably mounted to the tool body 214d by pivots 225d. Tapered, truncated expansion cones 274d are rotatably mounted on spindles of the arms 270d for expanding tubing when the tool is moved to the expanded configuration of FIG. 15. Again, a high expansion ratio is achieved by the relatively large movement of the expansion members 216d, as shown best in FIG. 14, the position of the cones 274d in the expanded configuration indicated by the broken reference line. The tool 22d is otherwise similar to the tool 22c of FIG. 11 and cam surfaces 76d defined by the arms 270d are illustrated in FIG. 13. These cam surfaces 76d abut the lower end 224d of the tool mandrel 226d during downward movement of the mandrel, to urge the expansion arms 270d outwardly to the expanded configuration. In further embodiments, the tools 22b, 22c or 22d may be activated through a combination of mechanical force applied to the respective tool mandrel and through circulation of fluid through the tool bore to force the mandrel downwardly. In alternative embodiments of the present invention (not illustrated), an expansion device may be provided incorporating a hoop stress inducing expansion tool of the type disclosed in the applicant's International patent application no. PCT/GB2002/005387, the disclosure of which is incorporated herein by way of reference. PCT/GB2002/005387 discloses expansion tools of the type adapted to be advanced through tubing without rotation, having a number of expansion rollers (some compliantly mounted) located with their respective axes perpendicular to a main axis of the tool. PCT/GB2002/005387 also discloses a hoop stress inducing expansion tool in the form of a compliant cone or mandrel, and expansion arms or fingers, which may be employed in the present invention. Reference is now made to FIG. 16 of the drawings, which shows a sectional view of a still further alternative expansion tool 22h. The tool 22h comprises a generally cylindrical body 12h (in this example, 197.10 mm outer diameter), the trailing end of the body 12h defining a box connection 14h for coupling to a corresponding pin connection provided on the lower end of a string of drill pipe (not shown), cone, mandrel or the like, as described above. The body 12h defines a throughbore 11h, to allow fluid to be passed through the tool 22h, the throughbore 11h including a recess 13h to accommodate a flow-restricting nozzle if required. Mounted on the leading end of the body 12h are three spindles 16h (only one shown), the spindle axes 18h lying parallel to the main body axis 20h. Each spindle 16h provides mounting for a respective expansion member in the form of a 30 degree conical profile 21h. In this example the profiles 21h describe a maximum diameter 23h of 220 mm, as illustrated in FIG. 17. The spindles 16h are essentially identical to one another and thus only the spindle 16h illustrated in section in FIGS. 16 and 18 of the drawings will be described in detail. The spindle 16h has a male threaded portion 24h which is received in a complementary female threaded bore 26h in the body end face 28h. The end of the spindle threaded portion also features a groove 30h housing an O-ring seal 32h, and an annular slot 33h for cooperation with a pin 34h which serves to further secure the spindle 20h to the body 12h. The leading end of the spindle, as illustrated in greater detail in FIG. 18 of the drawings, has a stepped profile and cooperates with a number of bearings to provide mounting for the conical profile 21h. Three journal bearings 36h, 38h, 40h are provided between the spindle 16h and the profile 21h, which is stepped internally in a corresponding manner, as may be seen from FIG. 18 of the drawings. In particular, the bearings comprise a needle roller bearing 36h, a roller thrust bearing 38h, and a taper roller bearing 40h. The free end of the spindle 16h is capped by a brass thrust cap 39h which sits upon a hexagonal wear insert 41h located in a corresponding recess in the end face of the spindle, and which insert wears preferentially to the spindle. Furthermore, each of the spindle 16h and the profile 21h define a respective bearing race 42h, 44h, into which an appropriate number of balls 46h are located via a port 48h in the profile 21h, and which port 48h may be closed by a plug 50h held in position by a circlip. The base of the profile 21h defines a groove 52h accommodating an O-ring seal 54h which serves to retain lubricant in the bearing area and also to prevent ingress of material. Lubricant for the bearings is retained within a sealed pressure-compensated system including a lubricant reservoir 60h, one reservoir 60h being provided for each profile 21h. The reservoir 60h is provided by the leading end of a longitudinally extending bore 62h which has been drilled from the trailing end of the body 12h, a piston 64h being movable within the bore 62h in response to external fluid pressure, and the piston being retained in the bore 62h by a circlip 65h. A conduit 66h extends from the reservoir 60h to the base of the spindle 16h. A conical recess 68h in the base of the spindle 16h in communication with the conduit 66h leads to a bore 70h extending along the spindle axis 18h, with branches 72h extending radially from the bore 70h to carry lubricant to the base of the journal bearing seats. One face of the piston 64h is exposed to external pressure, while the other face of the piston is in contact with the lubricant in the reservoir. Thus, the piston 64h may move in the bore 62h to compensate for changes in external pressure, in particular the increasing pressure experienced as the tool 22h is lowered into a bore. This minimizes the pressure differentials experienced by the seals 54h, thus increasing seal life. In use, the tool 22h is provided as part of an expansion device such as device 10 of FIG. 1, mounted to the lower end of a string of drill pipe and run into a bore. The device carrying the tool 22h may be run into the bore together with a tubular to be expanded, or may be run into a tubular which has been previously located in the bore. The leading end of the profiles 21h are located in the upper end of the tubular, while the tool 22h is rotated and axial force is applied to the tool. As the tool 22h rotates, the profiles 23h are rolled around the inner face of the tubular, and tend to reduce the wall thickness of the tubular such that the diameter of the tubular increases. As the tool 22h translates axially, the tubular is expanded to a diameter similar to the maximum diameter described by the profiles 21h. The rotary expansion of downhole tubulars, and in particular solid walled tubulars, subjects expansion tools to significant radial, axial and torsional loads. Furthermore, the expansion of the tubing tends to produce elevated temperatures, both in the tubing and the expansion tool. The provision of the combination of journal and roller bearings within a sealed lubrication system facilitates the free rolling motion necessary to achieve the desired uniform tubular expansion while minimizing induced torque and friction, and hence increased temperature. The tool construction provides a compact and robust arrangement well adapted to withstand the loads experienced in use, and the provision of a pressure-compensated bearing lubrication system reduces the pressure differential across the bearing seals and thus extends seal life. This increases bearing life and thus facilitates use of the tool 22h in the expansion of extended lengths of tubing downhole. In addition, those of skill in the art will appreciate that the present tool configuration combines the robustness and uniform expansion of fixed geometry expansion devices with the advantages of the reduced torques and loads required for operation of a rotary expansion device. The above embodiment features 30 degree angle profiles, however FIG. 19 of the drawings illustrates a profile 80h with a 20 degree angle, which will tend to induce a more gradual expansion. Reference is now made to FIGS. 20 to 23 of the drawings, which illustrate a still further alternative expansion tool 22i. The tool 22i includes five expansion members 102i, each including a tapering leading end portion 104i and a cylindrical trailing portion 106i. The spindles 108i on which the members 102i are mounted are each profiled to accommodate a thrust bearing 110i, a roller bearing 112i and a journal bearing 114i. Although the seals are not illustrated, the tool 22i incorporates a sealed lubrication system, including a lubrication reservoir 115i. The tool body 116i has a central portion which extends beyond the expansion members 102i and terminates in a pin connection 118i for coupling to a further part of a tool string, mandrel or the like. Rearwardly of the connection 118i is a cylindrical body portion 120i about which is mounted a contact sleeve 122i of low friction material such as PTFE. The sleeve 122i is in contact with the cylindrical portions 106i of the expansion members, and thus provides radial support for the members 102i. The tool 22i is operated in substantially the same manner as the tool 22h described above, but of course does not form the end of the tool string; other tools and devices will be mounted forwardly of the tool 100i, and which may include other expansion tools, as described above. Reference is now made to FIGS. 24 to 26, which show a still further alternative expansion tool 22j. The tool 22j shares many features with the tool 22h described above, including a sealed lubrication system having a lubricant reservoir 202j featuring a pressure-compensating piston (not shown). However, the tool 22j includes three tubing expansion modules 203j mounted in the tool body 206j. Each module 203j includes a spindle 209j and an expansion member in the form of a conical profile or cone 204j. As will be described below, providing an expansion tool with tubing expansion modules allows for quick replacement of any one of the modules in the operational environment. Also, unlike the fixed diameter tools 22h, 22i, this tool 22j is compliant, in that the modules 203j including the rotary expansion profiles or cones 204j are mounted to the tool body 206j such that the cones 204j may be individually moved radially inwardly to a limited extent to describe a smaller diameter. This is useful to accommodate, for example, incompressible bore restrictions which prevent the tubing being expanded to a preferred diameter, or variations in tubing wall thickness. The tool 22j is illustrated with the cones 204j in the minimum gauge position, hard against respective stops 208j on the body 206j. The cones 204j are each mounted to the spindle 209j which is threaded and pinned in a housing 210j, each housing 210j being pivotally mounted to the body 206j, via respective pins 212j. The pins 212j thus couple the modules 203j to the body 206j and allow the modules to be released from the body, if required. The clearance between the sides of each housing 210j and the slots in the body 206j which accommodate the housings 210j is minimized to ensure that the pins 212j experience only shear, and not bending forces. The degree of compliancy is provided by locating a spring, in this example a stack of three disc springs 214j, between the body 206j and each housing 210j, the degree of outward rotation of the housings being limited by the provision of appropriate stops 215j. As with the other tools 22h, 22i, this tool 22j defines a central through bore 216j to allow passage of fluid through the tool body 206j. In addition, three bores 218j branch off from the central bore 216j such that, in use, a cooling jet of liquid may be directed onto the portion of tubing undergoing expansion. The sealed lubrication system of the tool 22j, whilst similar in operation to that of the tool 22h, differs in that the lubrication system is provided as an integral part of each tubing expansion module 203j. In more detail, the lubrication system includes a lubrication reservoir 202j in each of the modules 203j. The reservoirs 202j each comprise cylinders formed in the spindle 209j of the respective modules, with a bore 211j extending through the spindle 209j and branches 213j extending radially from the bore 211j to the bearing seats. A piston is mounted in each cylinder 202j to pressure compensate for changes in external pressure. In variations in the structure of the tool 22j, the disc springs 214j may be replaced by radially mounted or angled pistons (not shown) in the tool body 206j, for urging the tubing expansion modules 203j outwardly in use, to pivot about the pins 212j. The modules 203j are thus radially inwardly movable against the pistons, in use, to provide a degree of compliancy in the tool. The pistons may be urged radially outwardly on flow of fluid through the tool or supply of fluid in a closed system to the piston. Reference is now made to FIGS. 27 to 30 which show a still further alternative expansion tool 22k. The expansion tool 22k shares many features with the tool 22h described above, including a sealed lubrication system and bores for allowing the passage of cooling fluid through the tool. In more detail, the tool 22k includes a generally cylindrical body 302k with three recesses 304k in the outer surface of the body 302k, in which three corresponding tubing expansion modules 306k are mounted. The top and bottom views of FIGS. 28 and 29 show the relative location of the modules 306k, which are spaced apart by 120 degrees. Each of the modules 306k includes a spindle 308k and an expansion member in the form of a conical profile 310k rotatably mounted on the spindle 308k. The profile 310k has a leading end defining a 30 degree angle. The recesses 304k in the body 302k are shaped to receive the spindles 308k, which include a rear end in the form of a curved plate 312k with a cylindrical spindle shaft 314k extending from the plate 312k. The plate 312k includes a number of mounting holes which receive fixing bolts (not shown) for coupling the spindle 308k to the body 302k. The conical profile 310k is mounted on the cylindrical shaft 314k with a series of journal bearings 316k, 318k and 320k between the conical profile 310k and the shaft 314k, the bearings held axially by lock nuts 322k, 324k. Each module 306k includes a lubrication system similar to that described above with reference to the tool 22h. A lower end 326k of the recess 304k receives the end of the shaft 314k for locating the module 306k in the body 302k. After the spindles 308k have been secured in the respective recesses 304k by the fixing bolts, a first restraint sleeve 328k is coupled to the body 302k by a co-operating threaded joint 330k and set screws 332k are located to secure the sleeve 328k against rotation. In addition, a second restraint sleeve 334k is coupled to the body 304k by a co-operating threaded joint 336k, to secure the end of the cylindrical shaft 314k in the lower end 326k of the recess 304k. The spindles 308k are then securely coupled to the body 302k with the conical profile 310k rotatable about the spindle ready for use in expanding tubing. The body 302k also includes three bores 338k which extend through the body and having outlets 340k, as best shown in FIG. 29. The bores 308k allow cooling fluid to flow to the tubing during expansion. The tool lubrication system is similar to that described with reference to the tool 22h, and a conduit 342k of the lubrication system is coupled to the bearing lubrication system and pressure compensated by a piston or diaphragm. Provision of the tool 22k including the tubing expansion modules 306k allows for quick replacement of any one of the modules 306k in the operational environment should any of the spindles 308k, conical profiles 310k or the bearings 316k to 320k require replacement or maintenance. In particular, it is not required to disassemble the entire tool to remove the modules 306k, nor to remove the conical profile 310k from the spindle 308k during removal. Instead, to release the modules 306k, the restraint sleeves 328k and 334k are released before removing the fixing bolts connecting the spindles 308k to the body 302k. The module 306k may then be removed and replaced as necessary. This both cuts down on the time and therefore operating costs of using the tool 300k and provides flexibility in use, as the procedure can be carried out in the operational environment, such as on the rig floor. Alternatively, the tool 300k may be broken-out (released) from a string carrying the tool for subsequent removal of the modules 306k in, for example, a workshop environment. In variations in the structure of the tool 22k, the tubing expansion modules 306k may be radially movably mounted (not shown) with respect to the tool body 302k, to provide the tool 22k with a degree of compliancy. For example, the modules 306k may be coupled to or may define a radially movable piston, the piston urged radially outwardly, in use, on flow of fluid through the tool or supply of fluid in a closed system to the piston. It will be understood that features of any one of the expansion tools of FIGS. 6 to 30 may be provided in combination in alternative expansion devices. Various modifications may be made to the foregoing without departing from the spirit and scope of the present invention. For example, any one of the expansion tools of FIGS. 7 to 15 may only include locking means or biasing means. The tool may be mechanically activated in any alternative fashion suitable for moving the mandrel down relative to the body. For example, the tool mandrel may be urged downwardly relative to the tool body by restraining the body and setting weight down on the mandrel. The snap ring may alternatively be disengaged downhole, such that the biasing spring returns the sub and mandrel to the de-activated position. This de-supports the rollers, which are now no longer able to exert an expansion force on the tubing, allowing the expansion tool to be returned to surface more easily. The snap ring may be released downhole by a release assembly such as release sleeve moved over the snap ring to cam the ring into the ring slot, allowing movement of the mandrel past the guide ring. Alternatively, the tool may include dogs or pins for moving the snap ring inwardly. In a further alternative, the snap ring may simply be sheared out. The mandrel may define a piston in place of a floating annular piston mounted on a shoulder of the mandrel, the mandrel shoulder may define the piston. Thus, for example, the annular piston of the tool may comprise an integral part of or may be coupled to the mandrel shoulder. The tool may be run on jointed tubing and may be driven from surface by a kelly or top drive. Where the expansion members of the tool are mounted on pivots, movement of the mandrel downwardly may rotate the rollers about the pivot such that the rollers describe an expanded diameter for expanding tubing. Where the tools are activated by fluid pressure, the respective tool mandrel may be urged downwardly either by providing the mandrel with a restriction nozzle to create a back pressure, or by defining a differential piston area across the floating annular piston, or by a combination of the two, as described above. In further alternatives, the tubing expansion modules of any one of the expansion tools of FIGS. 16 to 30 may be located at an angle to a main axis of the tubing expansion tool and may be angled towards a leading or lower end of the tool. The lubrication system may be provided with a lubrication fluid reservoir internally or externally of the tool and pressure compensated in any desired fashion such as by piston, diaphragm or the like. The arrangement of bearings in the tools may be any desired combination and may be tailored to the particular expansion procedure to be conducted. The spindles may be releasably coupled to the tool body using any suitable fixings such as screws, shear pins or the like. Whilst some of the above embodiments utilize cantilevered spindles, in other aspects of the invention spindles supported at both ends may be utilized. Additionally or alternatively, the expansion member module, and thus the expansion member may be skewed with respect to the main axis of the tool and may, for example, be generally helically oriented. Thus, the expansion member axis may extend at an angle with respect to the tool main axis. Mounting the expansion member skewed with respect to the tool axis causes the expansion member to exert a force on the tool body tending to advance the tool body through tubing being expanded on rotation of the tool body. The lubrication system may be adapted to be pressurized such that fluid in the lubrication system is under a higher pressure than fluid outside the system. Such overpressurising of the lubrication system promotes a positive displacement of the lubrication fluid from the system, in use, to prevent ingress of well fluids, solids or other contaminants into the lubrication system. The lubrication system may include a biased piston, for example, a spring biased piston or the like for pressurizing the lubrication system fluid above the pressure of fluid outside the system. The expansion members/modules may be at irregular angular spacings with respect to the tool body, if desired. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a device for use in tubing expansion and to methods of expanding tubing. In particular, but not exclusively, embodiments of the present invention relate to devices and methods for use in expanding tubing downhole. 2. Description of the Related Art In the oil and gas exploration and production industry, bores drilled to access subsurface hydrocarbon-bearing reservoirs are lined with tubing, known as casing and liner. Furthermore, strings of tubing may be located within the cased bore to, for example, carry production fluid to surface. Recently, there have been numerous proposals to use tubing which is expanded downhole, that is tubing of a first diameter is run into a bore and then expanded to a larger second diameter. This offers many advantages to the operator, primarily providing the ability to create lined bores which do not necessarily suffer a loss in internal diameter each time a string of tubing is located in the bore, beyond an existing section of tubing-lined bore. Early proposals for expanding tubing downhole featured the use of cones or mandrels, which are driven through the tubing in order to expand the tubing. Other proposals include the use of roller expanders, some of which feature radially-urged rollers. When tubing is expanded using a cone or mandrel, the expansion mode is different from when tubing is expanded using roller expanders. Typically, tubing expanded with a cone or mandrel tends to shorten in axial length whilst maintaining or suffering only a small reduction in wall thickness. Tubing expanded using roller expanders, however, tends to extend in axial length and experiences a reduction in wall thickness, caused by a wall thinning action. These two different types of expansion devices offer various advantages and disadvantages depending upon the particular circumstances in which the device is employed. Also, it is generally preferred to expand tubing in a top-down expansion procedure, as it is possible to recover the expansion device in the event that the tool becomes lodged in the tubing. However, when expanding tubing using an expansion cone or mandrel, it is conventional to employ a bottom-up expansion procedure. This is because it is necessary to apply a relatively large force on the cone from surface (by setting weight down on the cone), or to apply a relatively high pressure to the reverse face of the expansion cone (such as by supplying a pressurised fluid behind the cone), and it is not possible or safe to achieve the required loading or pressure on the cone in a top-down expansion procedure. This is particularly true for deviated (horizontal) wells and extended reach wells, where the forces required to expand tubing are, generally speaking, relatively high. It is amongst the objects of embodiments of the present invention to provide improved devices and methods for use in expanding tubing downhole. | <SOH> SUMMARY OF THE INVENTION <EOH>According to a first aspect of the present invention, there is provided a tubing expansion device comprising: at least one expansion member adapted to expand a tubing by inducing a hoop stress in the tubing; and at least one further expansion member adapted to expand the tubing by inducing a compressive yield of the tubing. It will be understood that the hoop stress in tubing is the stress in the tubing wall acting circumferentially in a plane perpendicular to an axis of the tubing. Tubing expanded by induced hoop stress experiences a different expansion mode compared to tubing expanded by compressive yield whereby the tubing tends to axially contract in length. Tubing expanded by compressive yield, however, tends to axially extend in length and experiences a reduction in the tubing wall thickness. The invention thus allows the relative advantages of these different expansion modes to be combined in a single device. The expansion device may be adapted to be translated through tubing to be expanded, and may be adapted to be rotated. Alternatively, the expansion device may be adapted to be advanced through tubing to be expanded without rotation. Preferably, the hoop stress inducing expansion member and the compressive yield inducing expansion member are arranged such that expansion of the tubing to a desired final diameter is carried out by the compressive yield inducing expansion member. The applicant has found that tubing expanded by compressive yield demonstrates improved material properties, particularly crush resistance, when compared to tubing expanded by a hoop stress, as disclosed in the Applicant's corresponding UK patent application No.0216074.5, the disclosure of which is incorporated herein by way of reference. Alternatively, if desired or appropriate, expansion to a desired final diameter may be carried out using the hoop stress inducing expansion member. Preferably, the hoop stress and compressive yield inducing expansion members are axially spaced, that is, axially separated, and/or circumferentially spaced, that is, spaced around a perimeter or circumference of the expansion device. The expansion members may be relatively axially and/or rotationally arranged according to at least one parameter of a tubing to be expanded, which may be selected from the group comprising: a pre-expansion diameter and/or wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion (which depends upon factors including the tubing material); a desired post-expansion strength and degree of collapse or crush resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. This final parameter may depend upon factors including the likelihood of the tubing becoming differentially stuck. This can occur, for example, when there is a large differential pressure between high pressure fluid (such as drilling fluid) in a borehole surrounding the tubing, and a formation having a relatively low formation pressure, such as a particularly permeable formation. This can cause the tubing to become adhered or stuck to a wall of the borehole. Accordingly, by balancing the axial extension and contraction effects of the different expansion modes, the tubing can be expanded without any change in axial length. The expansion members may be provided spaced alternately in an axial and/or rotational direction, and may be provided on separate portions or bodies, or as parts of separate tools, coupled together to form the expansion device. The expansion device may thus further comprise a hoop stress inducing expansion portion and a compressive yield inducing expansion portion, each carrying respective hoop stress and compressive yield inducing expansion members. The device may therefore be modular in nature, allowing a tool including a desired axial arrangement of the expansion tool portions, and thus of the hoop stress and compressive yield inducing expansion members, to be provided, according to particular requirements of the expansion device and, in particular, depending upon one or more parameter of the tubing to be expanded, as discussed above. The portions or tools may be coupled together, and may be restrained against relative rotation. Alternatively, at least one of said portions or tools may be rotatable relative to at least one other portion or tool. Thus where the device is rotated and translated through tubing, at least one of said portions or tools may remain rotationally stationary relative to the tubing. The hoop stress inducing expansion member may be adapted to contact the tubing over a majority of a circumference or perimeter of the tubing. The compressive yield inducing expansion member may be adapted to contact the tubing over part of a circumference or perimeter of the tubing, and may contact the tubing in a point or line contact. The expansion device may comprise a plurality of hoop stress inducing expansion members. Said expansion members may describe progressively increasing expansion diameters in a direction along an axial length of the device, to expand the tubing by progressively increasing degrees to a desired final diameter. The expansion device may additionally or alternatively comprise a plurality of compressive yield inducing expansion members. The compressive yield inducing expansion members may be arranged for movement to expansion positions describing progressively increasing expansion diameters in a direction along an axial length of the device. This may similarly facilitate expansion of the tubing to a desired diameter in progressive, incremental steps. The expansion device may comprise a plurality of hoop stress and/or a plurality of compressive yield inducing expansion portions or tools, which may be axially alternating. Alternatively, a number of hoop stress inducing expansion portions may be coupled together and joined to one or more compressive yield inducing expansion portions, or vice versa, or indeed in any other suitable arrangement. In a further alternative, the expansion device may comprise at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member provided as a single tool, portion, body or part. The hoop stress inducing expansion member may comprise a fixed expansion member. The hoop stress inducing expansion member may be fixed by coupling or mounting the member with respect to a remainder of the device, for rotation with respect to the tubing. Alternatively, the hoop stress inducing expansion member may be rotatable with respect to the tubing and may, for example, be rotatably mounted on or to a body of the device, such as by a bearing, swivel or the like. Thus where the tool is rotated on translation through the tubing, the hoop stress inducing expansion member may remain rotationally stationary relative to the tubing, save for any rotation due to a reaction force imparted on the member by the tubing. The hoop stress inducing expansion member may comprise a fixed diameter expansion member, such as a cone or mandrel, but may alternatively comprise a shoulder, arm, finger or the like. The expansion member may be formed integrally with or provided on or coupled to a body of the expansion device. Alternatively, the hoop stress inducing member may comprise a compliant expansion member such as a compliant cone, mandrel or the like, such as that disclosed in the applicant's International patent application no. PCT/GB2002/005387, the disclosure of which is incorporated herein by way of reference. It will be understood that a compliant expansion member is capable of inward deflection, for example, in the event that a restriction is encountered, such as an area of tubing which cannot be expanded. The device may further comprise a hoop stress inducing expansion tool, portion or body including a plurality of hoop stress inducing members, which may take the form of expansion rollers mounted for rotation about an axis substantially perpendicular to an axis of the tool, as disclosed in PCT/GB2002/005387. The expansion tool or portion may alternatively comprise a tapered expansion cone or mandrel with a plurality of rotary expansion members, such as rollers, rotatably mounted on the tapered cone, as disclosed in the applicant's International patent publication. no. WO 00/37766, the disclosure of which is also incorporated herein by way of reference. The hoop stress inducing expansion member may take the form of a collapsible expansion cone, mandrel or the like, which may be movable between a collapsed and an expansion position, in the expansion position, the cone adapted for expanding the tubing. The compressive yield inducing expansion member may comprise a rotary expansion member and may be rotatable with respect to the tubing. Preferably, the compressive yield inducing expansion member is rotatable relative to a body of the device about an expansion member axis. The expansion device may be adapted to generate a drive force for translating the device with respect to or through the tubing. This may facilitate expansion of the tubing in a top-down procedure when, in an embodiment of the invention, using an expansion cone, mandrel or the like as the hoop stress inducing expansion member. The drive force may be generated on rotation of the expansion device. The compressive yield inducing expansion member may be adapted to generate a drive force on the tubing, the generated drive force serving for at least partly translating the device with respect to the tubing. The expansion device may be adapted to be translated through the tubing by a combination of an external axial force, which may be applied through a tubing string coupled to the device and the generated drive force, or the generated drive force may be sufficient to translate the device through the tubing without an externally applied axial force. An axis of the compressive yield expansion member may be skewed with respect to a body of the device. This may generate an axial drive force on rotation of the device. Where the device comprises a plurality of said expansion members, the members may be rotationally spaced and helically oriented with respect to a body of the device, as disclosed in WO 00/37766. The compressive yield inducing expansion member may be adapted to expand the tubing by a relatively small amount compared to the expansion generated by the hoop stress inducing expansion member. For example, the compressive yield inducing expansion member may expand the tubing by less than 50%, typically less than 25% and preferably by less than 10% of the total expansion achieved using the expansion device. The compressive yield inducing expansion member may include a gripping surface for gripping the tubing to impart a drive force on the tubing, and may, for example, have a knurled or toothed gripping surface, or a combination thereof. The expansion device may be adapted to be rotated from surface by rotation of a tubing string coupled to the device, or by a downhole motor such as a turbine, positive displacement motor (PDM), electrical motor or the like. The compressive yield inducing expansion member may be provided as part of a compressive yield inducing expansion member module releasably coupled to a body of the device as a unit, and the compressive yield inducing expansion member may be rotatably mounted on a spindle. The spindle may comprise a cantilevered spindle extending from a body of the device. The expansion device may comprise a bearing between the compressive yield inducing expansion member and a body of the device, and a sealed lubrication system for containing lubricant to facilitate rotation of the compressive yield inducing expansion member relative to the body. The spindle may be pivotally coupled to the body. An axis of the spindle may be disposed at an angle with respect to a main axis of the tool. The compressive yield inducing expansion member may be radially moveably mounted with respect to a body of the device, for movement towards an expansion configuration describing an expansion diameter for expanding tubing to a predetermined diameter. The expansion member may be lockable in the extended configuration. The expansion member may additionally or alternatively be biased radially inwardly. Thus in the absence of an expansion force exerted on the compressive yield inducing expansion member, the expansion member may be biased towards a retracted configuration. The expansion member may be moveable in response to both: a) an applied mechanical force; and b) an applied fluid pressure force. The expansion member may be pivotally mounted with respect to a body of the device for movement towards the extended configuration. The above features are disclosed in the Applicant's UK patent application No. 0220933.6, the disclosure of which is incorporated herein by way of reference. According to a second aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: expanding the tubing at least in part by inducing a hoop stress in the tubing; and expanding the tubing at least in part by inducing a compressive yield of the tubing. The method may comprise expanding the tubing at least in part by rotary expansion, but the tubing may alternatively be expanded without rotation. The method may comprise providing an expansion device comprising a hoop stress inducing expansion member and a compressive yield inducing expansion member. The method may comprise expanding the tubing to a first diameter by inducing one of a hoop stress in the tubing and a compressive yield of the tubing, and subsequently expanding the tubing to a second, greater diameter by the other one of inducing a hoop stress in the tubing and a compressive yield of the tubing. For example, the method may comprise providing at least one expansion member adapted to expand a tubing by inducing a hoop stress in the tubing; and at least one further expansion member adapted to expand the tubing by inducing a compressive yield of the tubing, and arranging said expansion members such that on translation of the tool through the tubing, expansion of the tubing to a first diameter is carried out using the hoop stress inducing expansion member, and expansion to a second, greater diameter is carried out using the compressive yield inducing expansion member, or vice versa. The method may comprise arranging a hoop stress inducing expansion member and a compressive yield inducing expansion member relative to each other according to at least one parameter of tubing to be expanded, and the parameter may be selected from the group comprising: a pre-expansion diameter and/or wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength and degree of collapse resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. In one embodiment of the invention, the method may comprise expanding the tubing without any or with negligible change in axial length of the tubing. The tubing may be expanded by progressively increasing amounts to a desired final diameter, by providing a plurality of expansion members. The method may comprise providing a plurality of expansion tool portions, one expansion tool portion carrying at least one hoop stress inducing expansion member and another expansion tool portion carrying at least one compressive yield inducing expansion member. The expansion tool portions may be provided with a combination of hoop stress inducing compressive yield inducing expansion members. The method may comprise providing a hoop stress inducing expansion tool or portion and a compressive yield inducing expansion tool or portion, each having a respective expansion member, selecting a desired axial arrangement of the expansion tools or portions and coupling the tools or portions together according to the selected arrangement. The arrangement may be selected according to said at least one parameter defined above. The method may comprise inducing a hoop stress in the tubing by bringing an expansion member into contact with a majority of a circumference or perimeter of the tubing. The method may comprise inducing a compressive yield by bringing an expansion member into a line or point contact with the tubing, and rotating said expansion member around the circumference or perimeter of the tubing. The method may further comprise rotating the expansion device to generate a drive force for at least partly translating the device through the tubing. In an embodiment of the invention, the method comprises providing a compressive yield inducing expansion tool as disclosed in WO 00/37766, and with an axis of the compressive yield inducing expansion member at an angle with respect to a main axis of the device, and rotating said tool to generate the drive force. A hoop stress inducing expansion member such as a cone, mandrel or the like may be coupled to and thus driven by said expansion tool. At least one of the hoop stress inducing and compressive yield inducing expansion members may have an expansion member axis, the axis disposed at an angle with respect to a main axis of the device. Where the compressive yield inducing expansion member comprises a rotary expansion member, said expansion member may be rotatable about an expansion member axis, said axis disposed at an angle with respect to a main axis of the device. The expansion member axis may converge with the tool main axis towards a leading end of the device. The compressive yield inducing expansion member may be rotatably mounted on a spindle, which may be disposed at an angle with respect to the device main axis, of the expansion member may include a spindle which is rotatable relative to a body of the device, the spindle disposed at an angle with respect to the device main axis. According to a third aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: determining at least one parameter of a tubing; providing a tubing expansion device having at least one hoop stress inducing expansion member and at least one compressive yield inducing expansion member mounted for rotation with respect to a body of the tool, and with said hoop stress inducing expansion member and said compressive yield inducing expansion member provided in a desired arrangement relative to each other selected depending upon said parameter; and translating the tubing expansion device through the tubing. The step of providing said expansion device may comprise selecting the tubing expansion device from a group comprising a plurality of expansion devices each having a different arrangement of said hoop stress and compressive yield inducing expansion members. Thus an expansion device may be selected which is most appropriate for expanding the tubing, depending upon said determined parameter. Alternatively, the step of providing said expansion device may comprise assembling an expansion device with said hoop stress and compressive yield inducing expansion members provided in a desired arrangement selected depending upon said determined parameter. The parameter may be selected from the group comprising a pre-expansion diameter and wall thickness of the tubing to be expanded; a desired post expansion diameter and wall thickness of the tubing; an initial strength (yield strength) of the tubing to be expanded; the Young's Modulus of the tubing material; anticipated work hardening of the tubing during expansion; a desired post-expansion strength and degree of collapse resistance of the tubing; and an anticipated or desired degree of axial extension or contraction in length of the tubing. According to a fourth aspect of the present invention, there is provided a tubing expansion device comprising at least one fixed expansion member; and at least one rotary expansion member mounted for rotation with respect to a body of the tool. According to a fifth aspect of the present invention, there is provided a method of expanding tubing, the method comprising the steps of: providing a tubing expansion device having at least one fixed expansion member and at least one rotary expansion member mounted for rotation with respect to a body of the tool; and translating the tool through tubing to be expanded to expand the tubing in part by the fixed expansion member and in part by the rotary expansion member. | 20040325 | 20140610 | 20050113 | 96785.0 | 0 | SULLIVAN, DEBRA M | Tubing expansion | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,809,143 | ACCEPTED | Automatic configuration of function blocks in a signal analysis system | System and method for specifying a signal analysis function. User input is received specifying a first operation implementing at least a portion of a signal analysis function. Prior operations input by the user are programmatically analyzed to determine and assign an input source for the first operation that provides a first input signal, e.g., based on inputs and their signal or data types required for the first operation, one or more prior operations are determined that provide respective output signals of the respective signal or data types, where the one or more prior operations comprise the input source, and where the respective output signals comprise the first input signal. The first operation is performed on the first input signal, producing an output signal which is then displayed on a display. The programmatically analyzing, performing, and displaying are performed for each of a plurality of first operations input by the user. | 1. A memory medium comprising program instructions for specifying a signal analysis function, wherein the memory medium is in a computer system comprising a display, wherein the program instructions are executable to implement: receiving user input specifying a first operation, wherein the operation implements at least a portion of a signal analysis function; programmatically analyzing prior operations input by the user to determine an input source for the first operation, wherein the input source provides a first input signal; performing the first operation on the first input signal received from the input source, wherein said performing produces an output signal; displaying the output signal on the display; and performing said programmatically analyzing, said performing, and said displaying for each of a plurality of first operations input by the user. 2. The memory medium of claim 1, wherein said programmatically analyzing prior operations input by the user to determine an input source for the first operation further comprises: programmatically analyzing the first operation to determine one or more inputs required for the first operation and respective data types of each of the one or more inputs; and determining one or more prior operations of the prior operations that provide respective output signals of the respective data types, wherein the one or more prior operations comprise the input source, and wherein the respective output signals comprise the first input signal. 3. The memory medium of claim 1, wherein said programmatically analyzing prior operations input by the user to determine an input source for the first operation comprises: programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation; and determining a prior operation of the prior operations that provides an output signal of an appropriate signal type, wherein the appropriate signal type comprises one of the determined one or more appropriate signal types for the first operation, wherein the prior operation comprises the input source, and wherein the output signal comprises the first input signal. 4. The memory medium of claim 3, wherein the program instructions are further executable to implement: assigning the output signal of the appropriate signal type to the first operation as the first input signal. 5. The memory medium of claim 3, wherein the first operation corresponds to a first function block, and wherein said programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation comprises: querying the first function block to determine the one or more appropriate signal types for the first operation. 6. The memory medium of claim 5, wherein the first operation requires a plurality of input signals, and wherein said programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation further comprises: querying the first function block to determine a number of inputs required for the first operation; and programmatically analyzing prior operations input by the user to determine a plurality of input sources for the first operation corresponding to the number of input signals required for the first operation. 7. The memory medium of claim 4, wherein said determining a prior operation of the prior operations that provides an output signal of the appropriate signal type comprises: querying a database to determine the prior operation that provides an output signal of the appropriate signal type, wherein the database comprises information indicating respective output signal types of the prior operations. 8. The memory medium of claim 7, wherein said querying the database to determine the prior operation that provides an output signal of the appropriate signal type comprises: analyzing input/output (I/O) dependencies among the prior operations and the first operation, wherein the I/O dependencies indicate a proximity ordering of the prior operations with respect to the first operation; and querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. 9. The memory medium of claim 8, wherein the first operation requires a plurality of input signals, and wherein each of the plurality of input signals has a respective signal type; and wherein said querying the database to determine the prior operation that provides an output signal of the appropriate signal type further comprises: for each of the plurality of input signals, querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. 10. The memory medium of claim 8, wherein the first operation requires a plurality of input signals, and wherein each of the plurality of input signals has a respective signal type; and wherein said querying the database to determine the prior operation that provides an output signal of the appropriate signal type further comprises: iteratively querying the database regarding each of the prior operations to determine one or more prior operations that provide respective output signals of each of the respective signal types, based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as prior operations are found that provide respective output signals of the respective signal types or when there are no further prior operations to consider. 11. The memory medium of claim 1, wherein said programmatically analyzing prior operations input by the user to determine an input source for the first operation comprises: programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation; determining whether any prior operation of the prior operations provides an output signal of an appropriate signal type, wherein the appropriate signal type comprises one of the determined one or more appropriate signal types for the first operation; if any prior operation of the prior operations provides an output signal of an appropriate signal type, assigning the output signal of the appropriate signal type to the first operation as the first input signal; and if no prior operations provide an output signal of an appropriate signal type, displaying one or more additional operations that provide an output signal of the appropriate signal type; and receiving additional user input selecting an additional operation from the additional operations, wherein the additional operation comprises the input source for the first operation, and wherein the output signal of the additional operation comprises the first input signal. 12. The memory medium of claim 11, wherein, upon said selecting an additional operation, the memory medium further comprises: programmatically analyzing prior operations input by the user to determine an input source for the additional operation, wherein the input source provides an additional input signal; and performing the additional operation on the additional input signal received from the input source, wherein said performing produces an additional output signal. 13. The memory medium of claim 1, wherein the first operation and the prior operations each correspond to a respective function block, wherein the program instructions are further executable to implement: receiving user input modifying a configuration of a first function block, thereby changing input signal specifications for a corresponding operation, wherein original input signal specifications for the corresponding operation specify a first input signal type for the corresponding operation, and wherein the changed input signal specifications specify a second, different, input signal type for the corresponding operation; programmatically analyzing prior operations input by the user to determine an input source for the corresponding operation, wherein the input source provides a second input signal of the second, different, input signal type; and performing the corresponding operation on the second input signal received from the input source for the corresponding operation, wherein said performing produces a corresponding output signal. 14. The memory medium of claim 13, wherein the respective function blocks are displayed in a diagram that visually represents I/O relationships between the function blocks, wherein the program instructions are further executable to implement: when the I/O relationships between the function blocks change, automatically updating the diagram in accordance with the changed I/O relationships between the function blocks. 15. The memory medium of claim 1, wherein the first operation and each of the prior operations corresponds to a respective function block, wherein the program instructions are further executable to implement: receiving user input modifying a configuration of a first function block, thereby changing output signal specifications for a corresponding operation, wherein original output signal specifications for the corresponding operation specify a first output signal type for the corresponding operation, and wherein the changed output signal specifications specify a second, different, output signal type for the corresponding operation; programmatically analyzing prior operations input by the user to determine one or more function blocks configured to receive an output signal of the first function block according to the original output signal specifications; and if the one or more function blocks are configurable to receive the output signal according to the changed output signal specifications, configuring the one or more function blocks to receive the output signal according to the changed output signal specifications. 16. The memory medium of claim 15, wherein the program instructions are further executable to implement: if the one or more function blocks are not configurable to receive the output signal according to the changed output signal specifications, for each respective function block of the one or more function blocks, programmatically analyzing prior operations input by the user to determine an input source for the respective function block, wherein the input source provides a respective input signal; and performing the corresponding operation of the respective function block on the respective input signal received from the input source, wherein said performing produces a respective output signal. 17. The memory medium of claim 16, wherein the respective function blocks are displayed in a diagram that visually represents I/O relationships between the function blocks, wherein the program instructions are further executable to implement: when the I/O relationships between the function blocks change, automatically updating the diagram in accordance with the changed I/O relationships between the function blocks. 18. The memory medium of claim 1, wherein the signal analysis function comprises a plurality of operations, wherein the program instructions are further executable to implement: displaying an input signal for at least one of the plurality of operations. 19. A method for specifying a signal analysis function, the method comprising: receiving user input specifying a first operation, wherein the operation implements at least a portion of a signal analysis function; programmatically analyzing prior operations input by the user to determine an input source for the first operation, wherein the input source provides a first input signal; performing the first operation on the first input signal received from the input source, wherein said performing produces an output signal; displaying the output signal on a display; and performing said programmatically analyzing, said performing, and said displaying for each of a plurality of first operations input by the user. 20. A system for specifying a signal analysis function, comprising: a processor; and a memory coupled to the processor, wherein the memory stores program instructions for specifying a signal analysis function, wherein the program instructions are executable by a processor to: receive user input specifying a first operation, wherein the operation implements at least a portion of a signal analysis function; programmatically analyze prior operations input by the user to determine an input source for the first operation, wherein the input source provides a first input signal; perform the first operation on the first input signal received from the input source, wherein said performing produces an output signal; display the output signal on a display; and perform said programmatically analyzing, said performing, and said displaying for each of a plurality of first operations input by the user. 21. A system for specifying a signal analysis function, comprising: means for receiving user input specifying a first operation, wherein the operation implements at least a portion of a signal analysis function; means for programmatically analyzing prior operations input by the user to determine an input source for the first operation, wherein the input source provides a first input signal; means for performing the first operation on the first input signal received from the input source, wherein said performing produces an output signal; means for displaying the output signal on a display; and means for performing said programmatically analyzing, said performing, and said displaying for each of a plurality of first operations input by the user. | PRIORITY DATA This application claims benefit of priority of U.S. provisional application Ser. No. 60/495,478, titled “Mixed Signal Workbench”, filed Aug. 15, 2003, and whose inventors were Michael L. Santori, J. Clinton Fletcher, Alain G. Moriat, Philippe G. Joffrain, Christophe A. Restat, Christopher G. Cifra, John A. Pasquarette, and Richard Keene. This application also claims benefit of priority of U.S. provisional application Ser. No. 60/496,318, titled “A Mixed Signal Analysis System and Method of Use”, filed Aug. 19, 2003, and whose inventors were Michael L. Santori, J. Clinton Fletcher, Alain G. Moriat, Philippe G. Joffrain, Christophe A. Restat, Christopher G. Cifra, John A. Pasquarette, and Richard Keene. FIELD OF THE INVENTION The present invention relates to the field of signal analysis, and more particularly to a system and method for interactively specifying and performing signal analysis functions. DESCRIPTION OF THE RELATED ART Traditionally, high level text-based programming languages have been used by programmers in writing application programs. Many different high level text-based programming languages exist, including BASIC, C, C++, Java, FORTRAN, Pascal, COBOL, ADA, APL, etc. Programs written in these high level text-based languages are translated to the machine language level by translators known as compilers or interpreters. The high level text-based programming languages in this level, as well as the assembly language level, are referred to herein as text-based programming environments. Increasingly, computers are required to be used and programmed by those who are not highly trained in computer programming techniques. When traditional text-based programming environments are used, the user's programming skills and ability to interact with the computer system often become a limiting factor in the achievement of optimal utilization of the computer system. There are numerous subtle complexities which a user must master before he can efficiently program a computer system in a text-based environment. The task of programming a computer system to model or implement a process often is further complicated by the fact that a sequence of mathematical formulas, steps or other procedures customarily used to conceptually model a process often does not closely correspond to the traditional text-based programming techniques used to program a computer system to model such a process. In other words, the requirement that a user program in a text-based programming environment places a level of abstraction between the user's conceptualization of the solution and the implementation of a method that accomplishes this solution in a computer program. Thus, a user often must substantially master different skills in order to both conceptualize a problem or process and then to program a computer to implement a solution to the problem or process. Since a user often is not fully proficient in techniques for programming a computer system in a text-based environment to implement his solution, the efficiency with which the computer system can be utilized often is reduced. To overcome the above shortcomings, various graphical programming environments now exist which allow a user to construct a graphical program or graphical diagram, also referred to as a block diagram. U.S. Pat. Nos. 4,901,221; 4,914,568; 5,291,587; 5,301,301; and 5,301,336; among others, to Kodosky et al disclose a graphical programming environment which enables a user to easily and intuitively create a graphical program. Graphical programming environments such as that disclosed in Kodosky et al can be considered a higher and more intuitive way in which to interact with a computer. A graphically based programming environment can be represented at a level above text-based high level programming languages such as C, Basic, Java, etc. A user may assemble a graphical program by selecting various icons or nodes which represent desired functionality, and then connecting the nodes together to create the program. The nodes or icons may be connected by lines representing data flow between the nodes, control flow, or execution flow. Thus the block diagram may include a plurality of interconnected icons such that the diagram created graphically displays a procedure or method for accomplishing a certain result, such as manipulating one or more input variables and/or producing one or more output variables. In response to the user constructing a diagram or graphical program using the block diagram editor, data structures and/or program instructions may be automatically constructed which characterize an execution procedure that corresponds to the displayed procedure. The graphical program may be compiled or interpreted by a computer. A graphical program may have a graphical user interface. For example, in creating a graphical program, a user may create a front panel or user interface panel. The front panel may include various graphical user interface elements or front panel objects, such as user interface controls and/or indicators, that represent or display the respective input and output that will be used by the graphical program, and may include other icons which represent devices being controlled. Thus, graphical programming has become a powerful tool available to programmers. Graphical programming environments such as the National Instruments LabVIEW product have become very popular. Tools such as LabVIEW have greatly increased the productivity of programmers, and increasing numbers of programmers are using graphical programming environments to develop their software applications. In particular, graphical programming tools are being used for test and measurement, data acquisition, process control, man machine interface (MMI), supervisory control and data acquisition (SCADA) applications, modeling, simulation, image processing/machine vision applications, and motion control, among others. In parallel with the development of the graphical programming model, increasingly, much of the instrumentation related to the above fields of application, e.g., test and measurement, data acquisition, process control, etc., has been implemented as virtual instruments (VIs). A virtual instrument is a user-defined measurement and automation system that includes a computer (such as a standard personal computer) or workstation equipped with the application software (such as LabVIEW graphical programs), hardware (such as DAQ boards, or more specialized hardware boards, e.g., oscilloscope boards, arbitrary waveform generator boards, etc.), and driver software. Virtual instrumentation represents a fundamental shift from traditional hardware-centered instrumentation systems to software-centered systems that exploit the computational, display, productivity and connectivity capabilities of computers, networks and the Internet. Because virtual instruments exploit these computation, connectivity, and display capabilities, users can define and change the functionality of their instruments, rather than being restricted by fixed-functions imposed by traditional instrument vendors. Virtual instruments may be used to monitor and control traditional instruments, create computer-based systems that can replace traditional instruments at a lower cost, and develop systems that integrate measurement functionality with industrial automation. Additionally, giving users flexibility to create their own user-defined virtual instruments for an increasing number of applications in a wide variety of industries, and letting users leverage the latest technologies from computers, networking and communications generally shortens system development time and reduces both short- and long-term costs of developing, owning and operating measurement and automation systems, and may generally improve efficiency and precision of applications spanning research, design, production and service. Virtual instruments may thus effectively replace many traditional standalone hardware-based instruments, such as, for example, oscilloscopes, multi-meters, and so forth. Such virtual instruments provide a number of benefits over their hardware equivalents, such as, for example, lower cost of manufacture and distribution and ease of upgrades, among others. An exemplary virtual instrument system is the National Instruments' LabVIEW system, where, for example, graphical interfaces or “front ends” of various instruments, such as oscilloscopes, multi-meters, and arbitrary waveform generators, execute on a host computer system, often in conjunction with data acquisition (DAQ) hardware or other specialized boards, e.g., oscilloscope boards, multi-meter boards, and arbitrary waveform generator boards, etc., to provide respective functionality traditionally provided by standalone hardware devices. In some virtual instruments, some or all of the instrument functionality is implemented in software and executed on the host computer. Thus, a virtual instrument may be implemented completely in software (e.g., a “soft-scope”), or may implemented in both software and hardware, in contrast with traditional standalone hardware instruments. In some signal analysis applications, such as test and measurement, control, simulation, equipment design, etc., numerous instruments may be required to analyze various signals related to the application. The coordinated configuration and use of these instruments to perform the desired tasks of the application generally requires significant effort, e.g., custom programming and/or coordinated configuration of the devices, and thus is often tedious, time-consuming, and error prone. Thus, improved systems and methods for specifying and performing signal analysis functions are desired. SUMMARY OF THE INVENTION A plurality of function blocks are described for use in specifying and performing a signal analysis function utilizing a plurality of instruments, and a method presented for automatically configuring function blocks selected for inclusion in a plurality of functions blocks specifying or representing a signal analysis function. In one embodiment, each function block may include: a function block icon operable to be displayed in a graphical user interface (GUI) of a signal analysis function development environment, where the function block icon visually indicates a respective signal operation, and a set of program instructions associated with the function icon, where the set of program instructions are executable to perform the respective signal operation, possibly in conjunction with associated hardware. In a preferred embodiment, each function block is selectable from the plurality of function blocks by a user for inclusion in a set of function blocks, wherein each function block operates to perform the respective signal operation continuously upon being selected. Each function block may be operable to provide a respective output based on the respective signal operation, where the respective output is operable to be displayed in the GUI, provided as input to one or more other ones of the set of function blocks, and/or exported to an external device. The set of function blocks may be executable to perform the signal analysis function under the signal analysis function development environment using one or more of the plurality of instruments. Signal operations may be organized by function categories, such as (but not limited to): Create, I/O, Conditioning, Measurement, Processing, File, Test, and Conversion, among others. Thus, in one embodiment, a plurality of function blocks may be used in specifying and performing a signal analysis function utilizing a plurality of instruments. In a preferred embodiment, the plurality of instruments includes two or more virtual instruments (VIs), at least a portion of which may include respective hardware components. In one embodiment, each function block may be selectable from the plurality of function blocks by a user for inclusion in a set of function blocks, where each function block operates to perform the respective signal operation continuously upon being selected. For example, the user may select a first function block from a palette, menu, etc., in response to which the respective signal operation may be performed, preferably executing in a continuous manner until, for example, a stopping condition occurs or the user pauses or terminates the process. The user may then select one or more additional function blocks, which may similarly begin continuous respective operations in conjunction with the first function block. In one embodiment, each function block may be operable to provide a respective output based on the respective signal operation, where the respective output is operable to be displayed in the GUI, provided as input to one or more other ones of the set of function blocks, and/or exported to an external device. In other words, each function block may generate a respective output that may be used as input to or by other function blocks in the set of function blocks, transmitted to an external device coupled to the host computer, and/or displayed in a display tool, i.e., a graph or table, in the GUI. Additionally, one or more of the function blocks may be operable to receive a respective input based on the respective signal operation, where the function block is operable to perform the respective signal operation on the input, e.g., on a signal and/or data, and provide the results as output. In one embodiment, each function block may include an input and an output, where the input is operable to receive signals from one or more of: an external signal source, a file, and/or another function block, and where the output is operable to send resultant signals to one or more of: a display of the GUI, an external device, a file, and/or another, different, function block. Once the user has selected the set of function blocks, the set of function blocks may be executable to perform the signal analysis function under the signal analysis function development environment using one or more of the plurality of instruments. For example, in an embodiment where each function block executes substantially continuously upon selection by the user, when the user is done selecting the function blocks, the signal analysis function (specified and implemented by the set of function blocks) is already being performed. As another example, the user may stop the current execution of the signal analysis function (which was, for example, initiated in steps via the function block selection process), then re-initiate performance of the signal analysis function, thereby invoking execution of the set of function blocks. In another embodiment, information specifying the respective signal operations of the set of function blocks may be saved, e.g., as a script, that may be executed as desired under the signal analysis fuiction development environment. In one embodiment, the set of function blocks may be displayed in a diagram, e.g., in a specified display area of the GUI. The diagram may include one or more of: a linear sequence, a data flow diagram, a tree diagram, and a dependency diagram, among other types of diagram. The diagram may substantially visually represent I/O relationships between the function blocks. For example, where output from a first fimction block is provided as input to a second function block, this relationship may be graphically represented in the diagram, e.g., via a data flow line from the first function block to the second function block, via I/O signal icons displayed in, on, or proximate to each function block icon, and/or by the relative positions of the function blocks, and so forth. In one embodiment, when the I/O relationships between the function blocks change, the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. Thus, if a user changes an I/O relationship between function blocks, the diagram may be updated automatically to reflect the change. Thus, the diagram may comprise or visually represent a script (or equivalent) that is executable to perform the specified signal analysis function under the development environment. Said another way, the diagram may include information specifying the respective signal operations of the set of function blocks, where the information is executable to perform the signal analysis function under the signal analysis function development environment. In one embodiment of the present invention, input and/or output sources for a selected function block (signal operation) may be automatically selected by the system, e.g., based on heuristics or other rules. In other words, in embodiments where each signal operation is comprised in or associated with a respective function block, when a first fimction block is selected by the user that requires an input signal of a certain type, the system may attempt to programmatically determine a prior selected fimction block that provides as output a signal of that type, and may automatically assign that signal/function block as the input for the first function block. One embodiment of a method for programmatic (automatic) configuration of a function block may operate as follows: User input specifying a first operation may be received, where the operation implements at least a portion of a signal analysis fimction. In other words, the user may select or invoke a signal operation, e.g., by right-clicking on a prior fimction block, signal plot or icon, thereby invoking a menu, or otherwise invoking presentation of selectable operations, and selecting the first operation therefrom. Then, prior operations input by the user may be programmatically analyzed to determine an input source for the first operation, where the input source provides a first input signal. In other words, operations that have already been specified previously by the user may be analyzed to find an operation that provides an output signal suitable for use as input to the first operation. For example, in one embodiment, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, and determining a prior operation of the prior operations that provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, where the prior operation includes the input source, and where the output signal includes the first input signal. In some embodiments, the first operation may require a plurality of inputs, and so programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more inputs required for the first operation and respective data types of each of the one or more inputs, and determining one or more prior operations of the prior operations that provide respective output signals of the respective data types, where the one or more prior operations include the input source, and where the respective output signals include the first input signal. In one embodiment, the method may also include assigning the output signal (or signals) of the appropriate signal type to the first operation as the first input signal. Said another way, once an output signal has been determined that is of the appropriate type, then the first operation may be configured to receive the determined output signal (or signals) as input. As noted above, in one embodiment, the first operation may correspond to a first function block. In this case, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may include querying the first function block to determine the one or more appropriate signal types for the first operation. Similarly, where the first operation requires a plurality of input signals, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may also include querying the first fuiction block to determine a number of inputs required for the first operation, and programmatically analyzing prior operations input by the user to determine a plurality of input sources for the first operation corresponding to the number of input signals required for the first operation. In another embodiment, determining a prior operation of the prior operations that provides an output signal of the appropriate signal type may include querying a database to determine the prior operation that provides an output signal of the appropriate signal type, where the database includes information indicating respective output signal types of the prior operations. It should be noted that in various embodiments, the database may be stored and accessed on the host computer, or on a computer coupled to the host computer, e.g., over a network, such as, for example, the Internet. In one embodiment, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include analyzing input/output (I/O) dependencies among the prior operations and the first operation, where the I/O dependencies indicate a proximity ordering of the prior operations with respect to the first operation, and then querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may include analyzing the prior operations regarding input signal types and sources, and output signal types and sources for the prior operations and the first operation to determine an ordering of the operations (proximity ordering) based on the input and output dependencies of the operations, where, for example, each operation is considered adjacent to another if the output of one is the input of the other. Thus, in one embodiment, the proximity ordering may reflect or correspond to a breadth first traversal of a dependency graph (in a computer science theoretic sense) for the set of operations. In an embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type further may include, for each of the plurality of input signals, querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may iterate through the plurality of input signals for the first operation, and for each input signal, analyze the prior operations according to the proximity ordering to determine the prior operation (if any) that produces an output signal of the same type as (or a type compatible with) the input signal. In another embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include iteratively querying the database regarding each of the prior operations to determine one or more prior operations that provide respective output signals of each of the respective signal types, based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as prior operations are found that provide respective output signals of the respective signal types or when there are no further prior operations to consider. In other words, the method may iterate over the prior operations according to the proximity ordering, querying the database regarding each operation and comparing the output signal (or signals) from the operation to determine whether the output signal is of the same as, or a compatible type with, any of the input signals of the first operation. As noted, in a preferred embodiment, the method may stop searching for an input source for a particular input signal of the first operation as soon an input source is found that provides an output signal of the appropriate type. Thus, an input source (or input sources) may be determined that provides signals suitable for input to the first operation. The first operation may then be performed on the first input signal received from the input source, thereby producing an output signal, where the first operation is preferably performed in a substantially continuous manner. Thus, the first operation may (in substantially continuous fashion) process signals from the determine input source and generate corresponding output signals. In response to performing the first operation, in one embodiment, the output signal may be displayed on a display, e.g., in a GUI displayed by a display device such as a computer monitor. For example, as described above, the output signal may be displayed in the display section of the GUI as a signal plot or graph, as tabular data, e.g., in a spreadsheet type format, and/or via other information display means, such as, for example, software-implemented indicators, e.g., gauges, meters, digital displays, and so forth. The method may determine whether there are additional operations to be specified by the user, e.g., based on user input, and, if no further operations are to be specified, the method may terminate. If the method determines that further operations are to be specified, then the method may repeat, proceeding as described above, where the programmatically analyzing, performing, and displaying may be performed for each of a plurality of first operations input by the user. In one embodiment, if none of the prior operations provides an output signal of the appropriate type, the method may facilitate selection of a different operation by the user as a signal source for the first operation. For example, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, determining whether any prior operation of the prior operations provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, and, if any prior operation of the prior operations provides an output signal of an appropriate signal type, assigning the output signal of the appropriate signal type to the first operation as the first input signal, as described above. If no prior operations provide an output signal of an appropriate signal type, then one or more additional operations that provide an output signal of the appropriate signal type may be displayed, and additional user input received selecting an additional operation from the additional operations, where the additional operation includes the input source for the first operation, and where the output signal of the additional operation includes the first input signal. In other words, if a suitable prior operation cannot be found, additional operations may be presented to the user for selection, where the additional operations each preferably provide an output signal of the appropriate type for use as input to the first operation. Said another way, if no prior operation provides an output signal that is suitable for use as input by the first operation, the method may determine one or more other operations that provide a signal suitable for input to the first operation (e.g., that have not been previously included or selected by the user), and present these one or more other operations to the user for selection. For example, the one or more other operations may be presented in a palette, as options in a menu or dialog, or by any other means, as is well known in the art. In a preferred embodiment, upon selection (by the user) of an additional operation, the method may further include programmatically analyzing prior operations input by the user to determine an input source for the additional operation, where the input source provides an additional input signal, and performing the additional operation on the additional input signal received from the input source, thereby producing an additional output signal. In other words, once the additional (the other) operation is selected by the user, the method may attempt to automatically determine an input signal source for the additional operation, as described above with respect to the first operation. As mentioned above, in a preferred embodiment, the first operation and the prior operations each correspond to a respective function block. In one embodiment, the method may further include receiving user input modifying a configuration of a first function block, thereby changing input signal specifications for a corresponding operation, where original input signal specifications for the corresponding operation specify a first input signal type for the corresponding operation, and where the changed input signal specifications specify a second, different, input signal type for the corresponding operation. In other words, once one or more operations have been specified by the user, resulting in a corresponding one or more function blocks being displayed in the GUI (and the performance of the one or more operations), the user may provide input modifying one or more parameters for one of the function blocks, where the corresponding operation functions in accordance with the one or more parameters, and where the modified function block and corresponding operation require an input signal of the second, different, input signal type. Prior operations input by the user may then be programmatically analyzed to determine an input source for the corresponding operation, where the input source provides the second input signal of the second, different, input signal type, and the corresponding operation performed on the second input signal received from the input source for the corresponding operation, thereby producing a corresponding output signal. In one embodiment, the respective function blocks may be displayed in a diagram that visually represents I/O relationships between the function blocks, as described in some detail above. In one embodiment, when the I/O relationships between the function blocks change (e.g., as a result of modifying one or more of the function block/operation configurations, the addition or removal of an operation, etc.), the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. For example, if the user modifies a function block/operation to receive a different type of input signal than was originally specified, and the method automatically determines an assigns a different input signal source (i.e., a different function block) than currently specified (replacing the original input source for that function block), the diagram may be automatically updated to reflect the new configuration of or I/O relationships between the function blocks. The techniques described above with respect to input signals for the first operation or function block may also be applied with respect to output signals. For example, in an embodiment where the first operation and each of the prior operations corresponds to a respective function block, the method may also include receiving user input modifying a configuration of a first function block, thereby changing output signal specifications for a corresponding operation, where original output signal specifications for the corresponding operation specify a first output signal type for the corresponding operation, and where the changed output signal specifications specify a second, different, output signal type for the corresponding operation. The prior operations input by the user may be programmatically analyzed to determine one or more function blocks configured to receive an output signal of the first function block according to the original output signal specifications, and if the one or more function blocks are configurable to receive the output signal according to the changed output signal specifications, the one or more function blocks may be configured to receive the output signal according to the changed output signal specifications. In one embodiment, if the one or more function blocks are not configurable to receive the output signal according to the changed output signal specifications, for each respective function block of the one or more function blocks, prior operations input by the user may be programmatically analyzed to determine an input source for the respective function block (e.g., to replace the original or current specified input signal), where the input source provides a respective input signal, and the corresponding operation of the respective function block performed on the respective input signal received from the input source, where said performing produces a respective output signal. In other words, if a function block or operation is modified to output a different type of signal (instead of the type originally or previously specified), then any function blocks that are currently configured to receive an input signal of the original type may require a different input signal source to provide an input signal of the appropriate type (e.g., of the original type or of a type compatible with the original type), and so the prior operations may be analyzed to determine suitable input signal sources for the function blocks. Similar to the above, once the results of the modifications have been propagated through the function blocks, the function block diagram is preferably updated automatically to reflect any changes in the I/O relationships between the function blocks. Thus, various embodiments of the systems and methods described above may operate to automatically determine input signal sources for selected function blocks or operations, thereby determining and/or modifying I/O relationships between the function blocks or operations, and optionally, to automatically update a function block diagram to reflect the I/O relationships. BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings, in which: FIG. 1A illustrates a computer system operable to execute a graphical program according to an embodiment of the present invention; FIG. 1B illustrates a network system comprising two or more computer systems that may implement an embodiment of the present invention; FIG. 2A illustrates an instrumentation control system according to one embodiment of the invention; FIG. 2B illustrates an industrial automation system according to one embodiment of the invention; FIG. 3A is a high level block diagram of an exemplary system which may execute or utilize programs according to embodiments of the invention; FIG. 3B illustrates an exemplary system that may perform control and/or simulation functions; FIG. 4 is an exemplary block diagram of the computer systems of FIGS. 1A, 1B, 2A and 2B and 3B; FIG. 5 is a flowchart diagram illustrating one embodiment of a method for specifying a signal analysis function; FIG. 6 illustrates an example graphical user interface for specifying and performing signal analysis functions, according to one embodiment; FIG. 7 is a block diagram of an exemplary hardware setup suitable for performing a signal analysis function, according to one embodiment; FIGS. 8A-8G illustrate an example walk-through of an exemplary signal analysis function specification and performance, according to one embodiment; FIGS. 8H and 8I illustrate further examples and use of function blocks, according to one embodiment; FIG. 9 is a data flow diagram of the example system and process of FIGS. 8A-8G, according to one embodiment; FIG. 10 flowcharts one embodiment of a method for automatically configuring function blocks of a signal analysis function, according to one embodiment; FIGS. 11A and 11B are flowchart diagrams illustrating embodiments of a method for specifying and performing a sweep as part of a signal analysis function; FIGS. 12A-12D illustrate an embodiment of a graphical user interface for performing the methods of FIGS. 11A and 11B; FIGS. 13A-13H illustrate another embodiment of a graphical user interface for performing the methods of FIGS. 11A and 11B; FIG. 14 flowcharts one embodiment of a method for automatically displaying signal data based on signal type, according to one embodiment; FIGS. 15A-15F illustrate automatically displaying signal data based on signal type, according to various embodiments; FIG. 16A is a block diagram of a virtual interactive instruments architecture, according to one embodiment; FIG. 16B flowcharts one embodiment of a method of use for the system of FIG. 16A; and FIGS. 17A-17G illustrate various embodiments of an example soft front panel. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Incorporation by Reference The following references are hereby incorporated by reference in their entirety as though fully and completely set forth herein: U.S. provisional application Ser. No. 60/495,478, titled “Mixed Signal Workbench”, filed Aug. 15, 2003. U.S. provisional application Ser. No. 60/496,318, titled “A Mixed Signal Analysis System and Method of Use”, filed Aug. 19, 2003. U.S. Pat. No. 4,914,568 titled “Graphical System for Modeling a Process and Associated Method,” issued on Apr. 3, 1990. U.S. Pat. No. 5,481,741 titled “Method and Apparatus for Providing Attribute Nodes in a Graphical Data Flow Environment”. U.S. Pat. No. 6,173,438 titled “Embedded Graphical Programming System” filed Aug. 18, 1997. U.S. Pat. No. 6,219,628 titled “System and Method for Configuring an Instrument to Perform Measurement Functions Utilizing Conversion of Graphical Programs into Hardware Implementations,” filed Aug. 18, 1997. U.S. Patent Application Publication No. 20010020291 (Ser. No. 09/745,023) titled “System and Method for Programmatically Generating a Graphical Program in Response to Program Information,” filed Dec. 20, 2000. U.S. patent application Ser. No. 09/886,496, titled “System and Method for Programmatically Creating Graphical Program Code in a Graphical Program”, filed Jun. 20, 2001. Terms The following is a glossary of terms used in the present application: Memory Medium—Any of various types of memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a CD-ROM, floppy disks 104, or tape device; a computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; or a non-volatile memory such as a magnetic media, e.g., a hard drive, or optical storage. The memory medium may comprise other types of memory as well, or combinations thereof. In addition, the memory medium may be located in a first computer in which the programs are executed, or may be located in a second different computer which connects to the first computer over a network, such as the Internet. In the latter instance, the second computer may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums which may reside in different locations, e.g., in different computers that are connected over a network. Carrier Medium—a memory medium as described above, as well as signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a bus, network and/or a wireless link. Programmable Hardware Element—includes various types of programmable hardware, reconfigurable hardware, programmable logic, or field-programmable devices (FPDs), such as one or more FPGAs (Field Programmable Gate Arrays), or one or more PLDs (Programmable Logic Devices), such as one or more Simple PLDs (SPLDs) or one or more Complex PLDs (CPLDs), or other types of programmable hardware. A programmable hardware element may also be referred to as “reconfigurable logic”. Medium—includes one or more of a memory medium, carrier medium, and/or programmable hardware element; encompasses various types of mediums that can either store program instructions/data structures or can be configured with a hardware configuration program. Program—the term “program” is intended to have the full breadth of its ordinary meaning. The term “program” includes 1) a software program which may be stored in a memory and is executable by a processor or 2) a hardware configuration program useable for configuring a programmable hardware element. Software Program—the term “software program” is intended to have the full breadth of its ordinary meaning, and includes any type of program instructions, code, script and/or data, or combinations thereof, that may be stored in a memory medium and executed by a processor. Exemplary software programs include programs written in text-based-programming languages, such as C, C++, Pascal, Fortran, Cobol, Java, assembly language, etc.; graphical programs (programs written in graphical programming languages); assembly language programs; programs that have been compiled to machine language; scripts; and other types of executable software. A software program may comprise two or more software programs that interoperate in some manner. Hardware Configuration Program—a program, e.g., a netlist or bit file, that can be used to program or configure a programmable hardware element. Graphical Program—A program comprising a plurality of interconnected nodes or icons, wherein the plurality of interconnected nodes or icons visually indicate functionality of the program. The following provides examples of various aspects of graphical programs. The following examples and discussion are not intended to limit the above definition of graphical program, but rather provide examples of what the term “graphical program” encompasses: The nodes in a graphical program may be connected in one or more of a data flow, control flow, and/or execution flow format. The nodes may also be connected in a “signal flow” format, which is a subset of data flow. Exemplary graphical program development environments which may be used to create graphical programs include LabVIEW, DasyLab, DiaDem and Matrixx/SystemBuild from National Instruments, Simulink from the MathWorks, VEE from Agilent, WiT from Coreco, Vision Program Manager from PPT Vision, SoftWIRE from Measurement Computing, Sanscript from Northwoods Software, Khoros from Khoral Research, SnapMaster from HEM Data, VisSim from Visual Solutions, ObjectBench by SES (Scientific and Engineering Software), and VisiDAQ from Advantech, among others. The term “graphical program” includes models or block diagrams created in graphical modeling environments, wherein the model or block diagram comprises interconnected nodes or icons that visually indicate operation of the model or block diagram; exemplary graphical modeling environments include Simulink, SystemBuild, VisSim, Hypersignal Block Diagram, etc. A graphical program may be represented in the memory of the computer system as data structures and/or program instructions. The graphical program, e.g., these data structures and/or program instructions, may be compiled or interpreted to produce machine language that accomplishes the desired method or process as shown in the graphical program. Input data to a graphical program may be received from any of various sources, such as from a device, unit under test, a process being measured or controlled, another computer program, a database, or from a file. Also, a user may input data to a graphical program or virtual instrument using a graphical user interface, e.g., a front panel. A graphical program may optionally have a GUI associated with the graphical program. In this case, the plurality of interconnected nodes are often referred to as the block diagram portion of the graphical program. Node—In the context of a graphical program, an element that may be included in a graphical program. A node may have an associated icon that represents the node in the graphical program, as well as underlying code or data that implements functionality of the node. Exemplary nodes include function nodes, terminal nodes, structure nodes, etc. Nodes may be connected together in a graphical program by connection icons or wires. Data Flow Graphical Program (or Data Flow Diagram)—A graphical program or diagram comprising a plurality of interconnected nodes, wherein the connections between the nodes indicate that data produced by one node is used by another node. Graphical User Interface—this term is intended to have the full breadth of its ordinary meaning. The term “Graphical User Interface” is often abbreviated to “GUI”. A GUI may comprise only one or more input GUI elements, only one or more output GUI elements, or both input and output GUI elements. The following provides examples of various aspects of GUIs. The following examples and discussion are not intended to limit the ordinary meaning of GUI, but rather provide examples of what the term “graphical user interface” encompasses: A GUI may comprise a single window having one or more GUI Elements, or may comprise a plurality of individual GUI Elements (or individual windows each having one or more GUI Elements), wherein the individual GUI Elements or windows may optionally be tiled together. A GUI may be associated with a graphical program. In this instance, various mechanisms may be used to connect GUI Elements in the GUI with nodes in the graphical program. For example, when Input Controls and Output Indicators are created in the GUI, corresponding nodes (e.g., terminals) may be automatically created in the graphical program or block diagram. Alternatively, the user can place terminal nodes in the block diagram which may cause the display of corresponding GUI Elements front panel objects in the GUI, either at edit time or later at run time. As another example, the GUI may comprise GUI Elements embedded in the block diagram portion of the graphical program. Front Panel—A Graphical User Interface that includes input controls and output indicators, and which enables a user to interactively control or manipulate the input being provided to a program, and view output of the program, while the program is executing. A front panel is a type of GUI. A front panel may be associated with a graphical program as described above. In an instrumentation application, the front panel can be analogized to the front panel of an instrument. In an industrial automation application the front panel can be analogized to the MMI (Man Machine Interface) of a device. The user may adjust the controls on the front panel to affect the input and view the output on the respective indicators. Graphical User Interface Element—an element of a graphical user interface, such as for providing input or displaying output. Exemplary graphical user interface elements comprise input controls and output indicators Input Control—a graphical user interface element for providing user input to a program. Exemplary input controls comprise dials, knobs, sliders, input text boxes, etc. Output Indicator—a graphical user interface element for displaying output from a program. Exemplary output indicators include charts, graphs, gauges, output text boxes, numeric displays, etc. An output indicator is sometimes referred to as an “output control”. Computer System—any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network appliance, Internet appliance, personal digital assistant (PDA), television system, grid computing system, or other device or combinations of devices. In general, the term “computer system” can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium. Measurement Device—includes instruments, data acquisition devices, smart sensors, and any of various types of devices that are operable to acquire and/or store data. A measurement device may also optionally be further operable to analyze or process the acquired or stored data. Examples of a measurement device include an instrument, such as a traditional stand-alone “box” instrument, a computer-based instrument (instrument on a card) or external instrument, a data acquisition card, a device external to a computer that operates similarly to a data acquisition card, a smart sensor, one or more DAQ or measurement cards or modules in a chassis, an image acquisition device, such as an image acquisition (or machine vision) card (also called a video capture board) or smart camera, a motion control device, a robot having machine vision, and other similar types of devices. Exemplary “stand-alone” instruments include oscilloscopes, multimeters, signal analyzers, arbitrary waveform generators, spectroscopes, and similar measurement, test, or automation instruments. A measurement device may be further operable to perform control functions, e.g., in response to analysis of the acquired or stored data. For example, the measurement device may send a control signal to an external system, such as a motion control system or to a sensor, in response to particular data. A measurement device may also be operable to perform automation functions, i.e., may receive and analyze data, and issue automation control signals in response. A measurement device may further be operable to perform modeling or simulation functions, e.g., for use in design or testing procedures. FIG. 1A—Computer System FIG. 1A illustrates a computer system 82 operable to execute software programs according to various embodiments of the present invention. Various embodiments of a method for specifying and performing a signal analysis function are described below. It should be noted that as used herein, the term “signal analysis function” refers to any type of function that relates to the generation, acquisition, and/or analysis of signals, e.g., for measurement, testing, control, simulation or modeling, design, prototyping, and so forth. As shown in FIG. 1A, the computer system 82 may include a display device operable to display signal analysis results as the signal analysis function is created and/or executed. The display device may also be operable to display a graphical user interface during execution of the program. The graphical user interface may comprise any type of graphical user interface, e.g., depending on the computing platform. The computer system 82 may include a memory medium(s) on which one or more computer programs or software components according to one embodiment of the present invention may be stored. For example, the memory medium may store one or more programs, e.g., graphical programs, which are executable to perform the methods described herein. For example, the memory medium may store one or more software programs implementing a signal analysis function development environment, described below in detail, which may facilitate interactive specification, development, and execution of signal analysis functions. More specifically, the signal analysis function development environment may provide an integrated interface for a plurality of instruments for signal analysis, described below. Also, the memory medium may store a graphical programming environment used to create and/or execute such graphical programs. The memory medium may also store operating system software, as well as other software for operation of the computer system. Various embodiments further include receiving or storing instructions and/or data implemented in accordance with the foregoing description upon a carrier medium. FIG. 1B—Computer Network FIG. 1B illustrates a system including a first computer system 82 that is coupled to a second computer system 90. The computer system 82 may be connected through a network 84 (or a computer bus) to the second computer system 90. The computer systems 82 and 90 may each be any of various types, as desired. The network 84 can also be any of various types, including a LAN (local area network), WAN (wide area network), the Internet, or an Intranet, among others. The computer systems 82 and 90 may execute a program, e.g., a graphical program, in a distributed fashion. For example, computer 82 may execute a first portion of the block diagram of a graphical program and computer system 90 may execute a second portion of the block diagram of the graphical program. As another example, computer 82 may display the graphical user interface of a graphical program and computer system 90 may execute the block diagram of the graphical program. In one embodiment, the graphical user interface of the graphical program may be displayed on a display device of the computer system 82, and the block diagram may execute on a device 190 connected to the computer system 82. The device 190 may include a programmable hardware element and/or may include a processor and memory medium which may execute a real time operating system. In one embodiment, the graphical program may be downloaded and executed on the device 190. For example, an application development environment with which the graphical program is associated may provide support for downloading a graphical program for execution on the device in a real time system. Exemplary Systems Embodiments of the present invention may be involved with performing test and/or measurement functions; controlling and/or modeling instrumentation or industrial automation hardware; modeling and simulation functions, e.g., modeling or simulating a device or product being developed or tested, etc. Exemplary test applications where embodiments of the present invention may be used include hardware-in-the-loop testing and rapid control prototyping, among others. However, it is noted that the present invention can be used for a plethora of applications and is not limited to the above applications. In other words, applications discussed in the present description are exemplary only, and the present invention may be used in any of various types of systems. Thus, the system and method of the present invention is operable to be used in any of various types of applications, including the control of other types of devices such as multimedia devices, video devices, audio devices, telephony devices, Internet devices, etc., as well as general purpose software applications such as word processing, spreadsheets, network control, network monitoring, financial applications, games, etc. In other words, various embodiments of the present invention are contemplated for use in any field of application where signals are analyzed. FIG. 2A illustrates an exemplary instrumentation control system 100 which may implement embodiments of the invention. The system 100 comprises a host computer 82 which connects to one or more instruments. The host computer 82 may comprise a CPU, a display screen, memory, and one or more input devices such as a mouse or keyboard as shown. The computer 82 may operate with the one or more instruments to analyze, measure or control a unit under test (UUT) or process 150. As will be described in detail below, in a preferred embodiment, the computer 82 may execute software that utilizes various virtual instruments (VIs), possibly in conjunction with hardware devices (e.g., boards) and/or instruments coupled to the computer, to analyze signals related to an application, device, or phenomenon. The one or more instruments may include a GPIB instrument 112 and associated GPIB interface card 122, a data acquisition board 114 and associated signal conditioning circuitry 124, a VXI instrument 116, a PXI instrument 118, a video device or camera 132 and associated image acquisition (or machine vision) card 134, a motion control device 136 and associated motion control interface card 138, and/or one or more computer based instrument cards 142, among other types of devices. The computer system may couple to and operate with one or more of these instruments. The instruments may be coupled to a unit under test (UUT) or process 150, or may be coupled to receive field signals, typically generated by transducers. The system 100 may be used in a data acquisition and control application, in a test and measurement application, an image processing or machine vision application, a process control application, a man-machine interface application, a simulation or modeling application, or a hardware-in-the-loop validation application, among others. FIG. 2B illustrates an exemplary industrial automation system 160 which may implement embodiments of the invention. The industrial automation system 160 is similar to the instrumentation or test and measurement system 100 shown in FIG. 2A. Elements which are similar or identical to elements in FIG. 2A have the same reference numerals for convenience. The system 160 may comprise a computer 82 which connects to one or more devices or instruments. The computer 82 may comprise a CPU, a display screen, memory, and one or more input devices such as a mouse or keyboard as shown. The computer 82 may operate with the one or more devices to a process or device 150 to perform an automation function, such as MMI (Man Machine Interface), SCADA (Supervisory Control and Data Acquisition), portable or distributed data acquisition, process control, advanced analysis, or other control, among others. The one or more devices may include a data acquisition board 114 and associated signal conditioning circuitry 124, a PXI instrument 118, a video device 132 and associated image acquisition card 134, a motion control device 136 and associated motion control interface card 138, a fieldbus device 170 and associated fieldbus interface card 172, a PLC (Programmable Logic Controller) 176, a serial instrument 182 and associated serial interface card 184, or a distributed data acquisition system, such as the Fieldpoint system available from National Instruments, among other types of devices. FIG. 3A is a high level block diagram of an exemplary system which may execute or utilize programs, e.g., graphical programs, according to various embodiments of the present invention. FIG. 3A illustrates a general high-level block diagram of a generic control and/or simulation system which comprises a controller 92 and a plant 94. The controller 92 represents a control system/algorithm the user may be trying to develop. The plant 94 represents the system the user may be trying to control. For example, if the user is designing an ECU for a car, the controller 92 is the ECU and the plant 94 is the car's engine (and possibly other components such as transmission, brakes, and so on.) As shown, a user may create a graphical program that specifies or implements the functionality of one or both of the controller 92 and the plant 94. For example, a control engineer may use a modeling and simulation tool to create a model (graphical program) of the plant 94 and/or to create the algorithm (graphical program) for the controller 92. The user may then specify and/or execute a signal analysis function to perform various tests and measurements (analyses) on the model, the controller 92, and/or the plant 94, e.g., via one or more software programs implementing various embodiments of the present invention, e.g., via a signal analysis function development environment, described below in detail, which may facilitate interactive specification, development, and execution of signal analysis functions. FIG. 3B illustrates an exemplary system which may perform control and/or simulation functions. As shown, the controller 92 may be implemented by a computer system 82 or other device (e.g., including a processor and memory medium and/or including a programmable hardware element) that executes or implements a graphical program. In a similar manner, the plant 94 may be implemented by a computer system or other device 144 (e.g., including a processor and memory medium and/or including a programmable hardware element) that executes or implements a graphical program, or may be implemented in or as a real physical system, e.g., a car engine. In one embodiment of the invention, one or more graphical programs may be created which are used in performing rapid control prototyping. Rapid Control Prototyping (RCP) generally refers to the process by which a user develops a control algorithm and quickly executes that algorithm on a target controller connected to a real system. The user may develop the control algorithm using a graphical program, and the graphical program may execute on the controller 92, e.g., on a computer system or other device. The computer system 82 may be a platform that supports real time execution, e.g., a device including a processor that executes a real time operating system (RTOS), or a device including a programmable hardware element. In one embodiment of the invention, one or more graphical programs may be created which are used in performing Hardware in the Loop (HIL) simulation. Hardware in the Loop (HIL) refers to the execution of the plant model 94 in real time to test operation of a real controller 92. For example, once the controller 92 has been designed, it may be expensive and complicated to actually test the controller 92 thoroughly in a real plant, e.g., a real car. Thus, the plant model (implemented by a graphical program) is executed in real time to make the real controller 92 “believe” or operate as if it is connected to a real plant, e.g., a real engine. In the embodiments of FIGS. 2A, 2B, and 3B above, one or more of the various devices may couple to each other over a network, such as the Internet. In one embodiment, the user operates to select a target device from a plurality of possible target devices for programming or configuration using a graphical program. Thus the user may create a graphical program on a computer and use (execute) the graphical program on that computer or deploy the graphical program to a target device (for remote execution on the target device) that is remotely located from the computer and coupled to the computer through a network. Graphical software programs which perform data acquisition, analysis and/or presentation, e.g., for measurement, instrumentation control, industrial automation, modeling, or simulation, such as in the applications shown in FIGS. 2A and 2B, may also be referred to as virtual instruments, although as described above, in many cases the software programs may operate in conjunction with hardware, such as DAQ boards or other specialized hardware boards. For example, in one embodiment, one or more of the virtual instruments included in the system may include respective hardware boards that provide hardware based functionality for the virtual instrument. In various embodiments, the boards may be one or both of: a PC expansion board installed in the host computer system, e.g., a PCI card or other type of card; and a card, module, or cartridge that is operable to be inserted into a chassis coupled to the host computer, such as a PXI or GPIB chassis. Of course, any other types of chassis and boards may be used as desired. Such virtual instruments may be used in various embodiments of the present invention to perform signal analysis functions, as described below. FIG. 4—Computer System Block Diagram FIG. 4 is a block diagram representing one embodiment of the computer system 82 and/or 90 illustrated in FIGS. 1A and 1B, or computer system 82 shown in FIG. 2A or 2B. It is noted that any type of computer system configuration or architecture can be used as desired, and FIG. 4 illustrates a representative PC embodiment. It is also noted that the computer system may be a general purpose computer system, a computer implemented on a card installed in a chassis, or other types of embodiments. Elements of a computer not necessary to understand the present description have been omitted for simplicity. The computer may include at least one central processing unit or CPU (processor) 160 which is coupled to a processor or host bus 162. The CPU 160 may be any of various types, including an x86 processor, e.g., a Pentium class, a PowerPC processor, a CPU from the SPARC family of RISC processors, as well as others. A memory medium, typically comprising RAM and referred to as main memory, 166 is coupled to the host bus 162 by means of memory controller 164. The main memory 166 may store one or more software programs implementing various embodiments of the present invention. For example, the main memory 166 may store a signal analysis function development environment, described below in detail, which may facilitate interactive specification, development, and execution of signal analysis functions. More specifically, the signal analysis function development environment may provide an integrated interface for a plurality of instruments for signal analysis, described below. The main memory may also store operating system software, as well as other software for operation of the computer system. The host bus 162 may be coupled to an expansion or input/output bus 170 by means of a bus controller 168 or bus bridge logic. The expansion bus 170 may be the PCI (Peripheral Component Interconnect) expansion bus, although other bus types can be used. The expansion bus 170 includes slots for various devices such as described above. The computer 82 further comprises a video display subsystem 180 and hard drive 182 coupled to the expansion bus 170. As shown, a device 190 may also be connected to the computer. The device 190 may include a processor and memory which may execute a real time operating system. The device 190 may also or instead comprise a programmable hardware element. The computer system may be operable to deploy a graphical program to the device 190 for execution of the graphical program on the device 190. The deployed graphical program may take the form of graphical program instructions or data structures that directly represents the graphical program. Alternatively, the deployed graphical program may take the form of text code (e.g., C code) generated from the graphical program. As another example, the deployed graphical program may take the form of compiled code generated from either the graphical program or from text code that in turn was generated from the graphical program. FIG. 5—Flowchart of a Method for Specifying a Signal Analysis Function FIG. 5 illustrates a method for interactively specifying a signal analysis function. The method shown in FIG. 5 may be used in conjunction with any of the computer systems or devices shown in the above Figures, among other devices. It should be noted that in various embodiments, some of the steps shown may be performed concurrently, in a different order than shown, or omitted. Additional steps may also be performed as desired. As shown, this method may operate as follows. First, in 502, user input may be received specifying an operation, where the operation implements at least a portion of a signal analysis function. For example, in a preferred embodiment, the user input may be received to a graphical user interface (GUI) of a signal analysis function development environment, which, as noted above, may facilitate interactive specification, development, and execution of signal analysis functions. More specifically, the signal analysis function development environment may provide an integrated graphical interface for a plurality of instruments for signal analysis, examples of which are provided below with reference to FIGS. 6 and 8A-8I. As mentioned above, the signal analysis function development environment executes on a computer system that includes a display, i.e., a display device, such as a computer monitor, which operates to display the GUI. The GUI preferably includes a display window or panel for displaying signals and signal analysis results (from the operations). Various examples of operations for signal analysis are provided below. The user may specify the operation in any of a variety of ways. For example, in one embodiment the user may select (e.g., with a pointing device, such as a mouse) the operation from a menu. For example, a menu of selectable operations may be provided by the signal analysis fuiction development environment, e.g., from a menu bar. In one embodiment, the menu may be invoked from a graphical signal display of the signal analysis function development environment. For example, one or more signals (signal plots), e.g., generated by prior operations, may be displayed in a display window. The user may select a signal (or multiple signals) from the display, e.g., by clicking on the signal plot or a symbol for the signal in a plot legend of the display, upon which the menu may be presented. The user may then select the desired operation from the menu. In another embodiment the user may select the operation from a palette of function icons, where each function icon represents a respective operation. For example, the user may double click on the icon for the operation, thereby invoking a configuration GUI for the operation through which the user may provide input configuring the operation. As another example, the user may “drag and drop” the icon from the palette onto a diagram, active window, and/or another icon. In one embodiment, each function icon may be associated with or comprised in a respective function block, described below in detail. Similar to above, in one embodiment, the palette may be displayed in response to user input selecting a signal plot or signal icon from a display tool, e.g., a graphical display, of the signal analysis function development environment. Thus, in one embodiment, user input may be received to the graph (or other display tool) indicating one or more signals displayed in the graph. One or more operation options may then be presented in response, and user input received selecting an operation option from the provided one or more operation options, where the selected operation option indicates an operation to be performed on the indicated one or more signals. In a preferred embodiment, the one or more operation options presented to the user include only operation options appropriate for the selected one or more signals. In other words, the method may use information related to the signals (and optionally, information related to previously specified operations) to filter or otherwise limit the operation options presented to the user. For example, if the graph included a power spectrum for a signal, and the power spectrum plot or icon were selected to invoke the operation options, only those operations suitable for application to a power spectrum may be presented, e.g., determining a strongest frequency, average power, etc. Thus, in one embodiment, receiving user input specifying an operation may include: receiving user input to the graph indicating one or more signals displayed in the graph, and further receiving user input associating the one or more signals with a first icon of the plurality of icons displayed on the display, where after said associating, the operation represented by the first icon may be performed on the one or more signals. It is noted that other methods of selecting the operation are also contemplated, such as, for example, the user entering the name of the desired operation into a text entry field, although graphical selection methods are preferred. Signal Operations The selectable operations mentioned above may include any type of operation related to signals. For example, the operations contemplated may include: generating one or more signals, e.g., by reading one or more signals from a file, and/or synthesizing one or more signals algorithmically; receiving one or more signals from an external source; sending one or more signals to an external system; analyzing one or more signals and generating results based on the analysis; displaying one or more signals; displaying results of another operation; processing one or more signals, thereby generating one or more modified signals; and storing one or more signals, among others. In other words, the operations may include signal generation, acquisition, analysis, processing, storage, import, export, or transmission, among others. A more detailed list of signal operations is provided below. Additionally, the operations may utilize various instruments to perform their respective functionalities. As mentioned above, in a preferred embodiment, the signal analysis function development environment provides an integrated interface to a plurality of instruments, where the instruments may include virtual instruments (which may or may not include respective hardware boards), and optionally, standalone hardware instruments. For example, receiving one or more signals from an external source may include receiving one or more signals from a hardware device over a transmission medium and/or from a simulation. As another example, a first operation may generate a test signal, e.g., via a virtual arbitrary waveform generator, and export the signal to an external hardware device, such as a filter. The filter may process (filter) the signal and a resultant (filtered) signal may be received by a second operation, e.g., a virtual oscilloscope, which may then display the resultant signal, e.g., compared with the original test signal. Note that the virtual arbitrary waveform generator and/or the virtual oscilloscope may be implemented solely in software, or may be include both software and a hardware board. Examples of hardware boards contemplated for use in preferred embodiments of the present invention include: an E Series Multifunction DAQ (E-MIO), a High Speed Digitizer (Scope), and a Signal Sources (Arbitrary Waveform & Function Generators), as provided by National Instruments Corporation. In further embodiments, the hardware boards may include one or more of: an S Series Multifunction DAQ (S-MIO) board, a High-Speed Digital (DIO) board, and a Digital Multimeter (DMM) board, among others. Thus, the instruments to which access may be provided by the signal analysis function development environment may include virtual instruments, such as a DAQ (data acquisition) device, a digitizer, an arbitrary waveform generator (arb), a digital I/O device, and a digital multimeter, among others, some of which may include corresponding hardware, such as a DAQ board, scope (digitizer) board, an arb board, a digital I/O board, and a digital multimeter board, etc., as described above, and may optionally also include at least one standalone hardware-based instrument, such as, for example, a standalone oscilloscope, multi-meter, waveform generator, hardware filter, etc. Thus, the signal analysis fuiction development environment may provide access to a plurality of instruments, where the plurality of instruments includes two or more virtual instruments, and may optionally include one or more standalone hardware devices. In 504, the operation may be performed in response to the specifying of 502. The operation is preferably performed utilizing at least one of the plurality of instruments to perform the operation. Generally the performance of the operation results in some form of output, such as, for example, signal data (a signal) or other resultant data that may then be displayed in a display tool of the GUI, e.g., in a graph (e.g., for signal plots) or in a table (e.g., for tabular scalar data). Examples of signal data displays are provided below with reference to FIGS. 8A-8I. It should be noted that other types of data displays are also contemplated, including, for example, histograms and 3D plots, among others. It should be further noted that in a preferred embodiment, one or more input signals for the operation may be displayed. More generally, as described below, in a preferred embodiment, the signal analysis function may include a plurality of operations, each of which may include one or more input signals and/or one or more output signals, and so the method may include displaying any of the input and/or output signals, as desired. In 506, an icon may be displayed on the display in response to the specifying of 502, where the icon comprises a graphical representation of the operation, and where the icon is displayed upon the specifying. In other words, once the operation is specified in 502, the corresponding icon for the operation is displayed. In 508, information specifying the operation may be stored. For example, the information may be stored in a data structure, such as a file, or transmitted to another system for storage. In a preferred embodiment, the steps of 502-508 may be repeated a plurality of times to specify the signal analysis function, as indicated in FIG. 5. In other words, the user may interactively specify a plurality of operations, thereby invoking performance of each operation upon its invocation and display of the icon corresponding to the operation. In a preferred embodiment, the operations in the signal analysis function include at least one of 1) generating signals displayed in a graph, and 2) modifying one or more signals displayed in the graph. In another embodiment, the operations in the signal analysis function may also include 3) producing an output based on one or more signals displayed in the graph and/or 4) exporting a signal. Of course, in various embodiments, other display tools than graphs may be used, such as tables for displaying tabular signal data. In other embodiments, the operations in the signal analysis function may include any or all of the signal operations described above in the Signal Operations section. It should be noted that after each respective operation is specified, the operation is preferably continuously performed during the repeating. In other words, once an operation has been specified, the operation executes in a substantially continuous fashion until removed from the signal analysis function or until the signal analysis function is terminated or paused. Note that in general, the signal operations typically relate to one or more of signal generation, signal acquisition, and signal processing or analysis, although other operations are also contemplated. In one embodiment, as a result of said repeating, a plurality of icons are displayed on the display representing a plurality of operations, where the plurality of icons are arranged to visually indicate the signal analysis function. In other words, in one embodiment, a diagram including the icons of the specified operations is displayed, where the diagram visually indicates the functionality of the signal analysis function. In various embodiments, the diagram may be one or more of: a linear sequence, a data flow diagram, a tree diagram, and a dependency diagram. Additionally, in a preferred embodiment, repeating the steps above produces a set of stored information representing the plurality of operations in the signal analysis function. In a preferred embodiment, the stored information corresponds to the diagram. As mentioned above, the method described above is preferably performed by program instructions executing under a signal analysis function development environment. In one embodiment, the set of stored information specifying the plurality of operations is executable in the signal analysis function development environment to perform the signal analysis function. Thus, in one embodiment, the program instructions (executing under the signal analysis function development environment) are further executable to implement executing the set of stored information to perform the signal analysis function. For example, in one embodiment, the set of stored information may comprise a script which is executable under the signal analysis function development environment to perform the signal analysis function. As FIG. 5 shows, in 510, the method may optionally generate a program, i.e., executable code, based on the set of stored information, where the generated program implements the signal analysis function, and is executable to perform the signal analysis function. Further details of the programmatic generation of the program are provided below in the section titled Code Generation. Thus, the specification of the plurality of operations produces the signal analysis function, where the signal analysis function utilizes at least a first plurality of the plurality of instruments, and where the plurality of instruments comprises two or more virtual instruments (VIs). Thus, the memory medium of the host computer may store a plurality of virtual instruments, where each of the virtual instruments is executable on the computer system to implement an instrument function, and where the plurality of operations utilize two or more different ones of the plurality of virtual instruments. For example, in one embodiment, the plurality of virtual instruments may include a signal generator VI, an oscilloscope VI, and a multimeter VI. As noted above, in one embodiment, at least a portion of the plurality of virtual instruments operate in conjunction with respective hardware boards. For example, an oscilloscope VI may include an oscilloscope card (board) that provides hardware for at least a portion of the oscilloscope functionality of the VI. As also noted above, the plurality of instruments may optionally further include at least one standalone hardware device (instrument). In other words, in addition to the virtual instruments, in some embodiments, the computer may also be coupled to one or more standalone hardware based instruments, such as, for example, a standalone oscilloscope, multi-meter, waveform generator, hardware filter, etc., where one or more of the specified operations may be operable to receive signals from, or provide signals to, one or more of the standalone instruments. In one embodiment, the method may further include specifying a relationship between a first icon and a second icon, thereby specifying a relationship between a first operation and a second operation, where specifying the relationship between the first icon and the second icon includes specifying that data produced by the first operation is used by the second operation. For example, in one embodiment, the relationship may be specified in response to user input indicating the relationship, e.g., user input indicating, say, that the output of the first operation is provided as input for the second operation, e.g., via drag and drop techniques, the user drawing “wires” between the two icons, right-clicking on an icon and invoking a menu whereby the relationship is specified by user selection, etc. In another embodiment, the relationship may be performed programmatically, e.g., automatically. For example, in one embodiment, when an operation is specified or selected, prior operations input by the user may be programmatically analyzed to determine an input source for the operation, i.e., to determine a prior operation that provides the appropriate input for the selected operation, e.g., based on chronology, signal type, format, etc. In other words, a heuristic based on one or more attributes of the selected operation and attributes of the prior operations may be used to determine the relationship, e.g., a default relationship, between the specified operation and at least one of the previously specified operations. Of course, once this relationship is determined, the user may modify or replace the determined relationship. In one embodiment, the relationships between operations or, more specifically, between operation icons, may be visually represented. For example, in one embodiment, each operation icon may display labels or images indicating their respective input and/or output signals. Thus, an I/O relationship between operation A and operation B, where A's output is B's input, may be indicated simply by A's icon including an output icon (e.g., symbol, label, or image) with the label “B”, and B's icon including an input icon with the label “A”. In one embodiment, the icons or labels may be displayed as part of the icon. In another embodiment, the icons or labels may be displayed only when invoked by the user, e.g., by right-clicking on the icon, hovering the cursor over the icon, and so forth. Other types of icons are also contemplated. For example, in one embodiment, each operation may have a symbol as well as an icon, where the operation icon displays its own symbol, and where the symbol may also be displayed as input/output signal icons displayed in or by other icons, indicating their respective input/output signals. As another example, similar to the “wires” used to indicate couplings between graphical program nodes in graphical programs, directional lines or graphical vectors may be displayed showing the relationship between operations. In one embodiment, once an operation has been specified, the user may configure the operations, where, for each operation, configuring the operation affects functionality of the operation. Note that in general, this configuration may occur while previously specified operations (and the present operation) are executing substantially continuously. For example, in one embodiment, during said repeating, user input to one or more of the icons may be received for configuring one or more of the plurality of operations, where receiving user input for configuring one or more of the plurality of operations does not include receiving user input specifying programming language code to configure the operations. In other words, the user preferably does not have to manually program (using a programming language) to configure the operation. For example, in one embodiment, for each operation to be configured, a graphical panel including one or more graphical user interface elements for setting properties of the operation may be displayed, and user input to the graphical panel received to set one or more properties of the operation. In other words, the user may invoke a configuration GUI for configuring the operation, e.g., by right-clicking on the operation's icon. In another embodiment, the configuration GUI may be displayed automatically, e.g., when the operation is originally specified, when another operation is associated with the operation, e.g., when a relationship between operations is specified or indicated, and so on. In one embodiment, one or more operations may also be removed from the plurality of operations. For example, in one embodiment, user input may be received specifying removal of a first operation from the plurality of operations. In response to specifying the removal of the operation, the method may include: discontinuing performance of the first operation from the plurality of operations, discontinuing display of the first icon, removing information associated with the first operation from the set of stored information, and modifying one or more signals displayed in the graph, as needed. Code Generation As noted above, in one embodiment, the set of stored information may comprise a script or equivalent which is executable under the signal analysis function development environment to perform the signal analysis function. In another embodiment, where the method described above executes under the signal analysis function development environment, a program implementing the plurality of operations may be programmatically generated based on the set of stored information, as noted above in 510, where the program is executable outside of the signal analysis function development environment. In other words, once the information specifying or representing the set of operations is produced and/or stored, the method may include programmatically generating a corresponding program that may be executed outside the development environment. Thus, the generated program may be saved, exported to other systems, etc., and executed independently of the signal analysis function development environment. In a preferred embodiment, the generated program is a graphical program, such as a LabVIEW graphical program, although it should be noted that in other embodiments, the generated program may be text-based, e.g., C++, C, etc., and/or interpretable under a different execution environment, such as, for example, Visual Basic, etc. As noted above, a graphical program preferably includes a plurality of interconnected graphical program nodes or icons that visually represent the functionality of the program, e.g., of the signal analysis function. The nodes may be interconnected in one or more of a data flow, control flow, or execution flow format. As also noted above, the graphical program may comprise a block diagram and may also include a user interface portion or front panel portion. Where the graphical program includes a user interface portion, the user may optionally assemble or modify the user interface on the display. As one example, the user may use the LabVIEW graphical programming development environment to modify or configure the graphical program. In one embodiment, each icon of the plurality of icons may correspond to one or more nodes in a graphical programming development environment, e.g., in the LabVIEW graphical programming development environment. Thus, the iconic display mentioned above (the diagram or diagrams described above) may have a relatively straightforward mapping or correspondence with a graphical program, which, as noted above, may include a plurality of interconnected nodes that visually represent the functionality of the graphical program. Since there is a correspondence between the stored information and the icons, in one embodiment, the graphical program may be generated based on the set of stored information, where the graphical program comprises a plurality of interconnected nodes which visually indicate the signal analysis function, and where the graphical program is executable to perform the signal analysis function. Similar to the removal of an operation described above, in one embodiment, user input specifying removal of a first operation from the plurality of operations may be received, in response to which a first operation may be removed from the plurality of operations. The one or more nodes corresponding to the first operation may then be removed from the graphical program in response to removing the first operation. As described above, the method may be performed by or under a signal analysis function development environment. For example, a graphical user interface (GUI) may be displayed that provides access to a set of operations, and where receiving user input specifying the plurality of operations includes receiving the user input to the graphical user interface specifying the plurality of operations, where the plurality of operations are selected from the set of operations. For example, as mentioned above in 502, the user may specify the operation in any of a variety of ways, such as, for example, selecting the operation from a menu or palette provided by the GUI. Similar to above, in one embodiment, receiving the user input to the graphical user interface specifying the plurality of operations does not include receiving user input specifying programming language code to implement the plurality of operations. In other words, manual programming is preferably not required. It should be noted that in some embodiments, the set of stored information representing or specifying the operations may include configuration information for the plurality of instruments to perform the signal analysis fuiction. For example, the configuration information may include parameter values for software based instruments, such as a “soft-scope”, for hardware components of virtual instruments, e.g., a scope card, and/or for standalone hardware based instruments. Thus, when the stored information is executed, e.g., in the form of a script, the relevant software and/or hardware used by or for the operations may be configured programmatically prior to, or as part of, performance of the operations. Similarly, in embodiments where an executable program, e.g., a graphical program, is generated (from the stored information), the program may include the configuration information, e.g., in the form of property or configuration nodes. When the program is executed, the appropriate software and/or hardware may be configured in accordance with the configuration information included in the program. In one embodiment, if any of the software and/or hardware is not included in the system, an error message or equivalent may be presented to the user indicating the missing software and/or hardware, allowing the user to take the appropriate actions to ensure sure that the system is complete, i.e., that the needed resources are available and/or installed on the system. Thus, in summary of the above, user input invoking each of a plurality of operations may be received, where the plurality of operations implement a signal analysis function, where for each respective instance of the user input invoking a respective operation, the respective operation is performed in response to the invoking, where the operation utilizes at least one of the plurality of instruments to perform the signal analysis function, displaying an icon in response to the invoking, where the icon corresponds to the respective operation and includes a graphical representation of the respective operation, and where the icon is displayed upon the respective invoking, and storing information specifying the operation. A graph may be displayed including one or more signals based on one or more of the plurality of operations (e.g., input signals and/or output signals). Additionally, the plurality of operations preferably utilize at least a first plurality of the plurality of instruments, where the plurality of instruments includes two or more virtual instruments. Said another way, user input invoking each of a plurality of operations may be received, where the plurality of operations implement a signal analysis function. Each of the plurality of operations may be performed in response to respective ones of said invoking, where each operation is performed upon each said invoking, where the plurality of operations utilize at least a subset of the plurality of instruments to perform the signal analysis function, and where the plurality of instruments includes two or more virtual instruments. Each of a plurality of icons may be displayed in response to said invoking, where each icon corresponds to a respective one of the plurality of operations, and where each icon is displayed upon each said invoking. Information specifying the plurality of operations may be stored, and results of one or more of the plurality of operations displayed, where the results include one or more tables of data, and/or one or more graphs each comprising one or more signal plots. Function Blocks (Signal Operations) As noted above, in some embodiments, the icons and operations may comprise or be comprised in function blocks, where each function block provides a respective specified operation and is represented by a respective icon. A list of signal operations organized by function categories follows. Note that the operations presented are meant to be exemplary only, and are not intended to limit the operations to any particular set or domain. Examples of function blocks and their use are illustrated in FIGS. 8A-8I, and described below. Create Basic Function—Create a signal waveform such as sine tone, square wave or noise. Multisine—Create a signal waveform composed of a number of sine tones. IO Acquire Analog DMM—Single point measurement of DC and AC values. Scope—Multiple channels waveform acquisition using a Digitizer board. EMIO-AI—Multiple channels waveform acquisition using an EMIO board. SMIO—Multiple channels waveform acquisition using an SMIO board. Generate Analog Function Generator—Continuous generation of a standard function waveform, such as sine tone or square wave. Arbitrary Waveform Generator—Generation of an arbitrary waveform such as, for example, create by the Basic Function block. EMIO-AO—Generation of an arbitrary waveform such as, for example, create by the Basic Function block. SMIO-AO—Generation of an arbitrary waveform such as, for example, created by the Basic Function block. Generate Digital DIO-DO—Continuous generation of digital patterns such as, for example, created by the Analog to Digital block. Acquire Digital DIO-DI—Continuous acquisition of digital patterns for example, to be converted to waveform using the Digital to Analog block. Conditioning Arithmetic—Performs simple operations such as addition, multiplication or E-norm on two signals. This polymorphic block supports both time domain and frequency domain signals. Filter—Performs filtering on one or more time domain waveforms. Resample—Resamples time domain or frequency domain signals to user defined conditions. Scaling—Applies user defined gain and offset to a signal. This polymorphic block supports both time domain and frequency domain signals. Window—Applies a window to a time domain waveform. Averaging—Performs averaging on time or frequency domain signals as well as scalar values. Subset—Extracts a signal subset. This polymorphic block supports both time domain and frequency domain signals. Scalar Processing—Performs formula node based operation (e.g., log, exp, sin, cos, etc.) on a scalar or array of scalars. Graph Align—Allows the user to manually (graphically) or automatically align two waveforms and returns the applied (or needed) scaling parameters. Measurement DC-RMS—Returns the DC and RMS values of an input signal. This block may operate on both time domain waveforms and Power or Magnitude Spectra. Distortion—Measures and returns various distortion values such as THD or specific harmonics for an input time domain waveform. Histogram—Computes the histogram of a signal. This polymorphic block supports both time domain and frequency domain signals. Tone Extraction—Extracts single tones from input time domain waveforms and returns various scalar information such as frequency, amplitude and phase, as well as reconstructed time domain or frequency domain signals. Processing Frequency Domain Power Spectrum—Computes the Power Spectrum of an input time domain waveform. Frequency Response—Computes the frequency response of a system based on two time domain waveforms representing the system excitation and response signals. File Import from File—Imports a signal or a group of signals from file. This polymorphic block supports both time domain and frequency domain signals. Export to File—Exports a signal or a group of signals to file. This polymorphic block supports both time domain and frequency domain signals. Test Test Blocks—Various blocks for performing tests on signals. Each block typically returns a Boolean specifying whether the test has passed or failed. Conversion (Tools) Analog to Digital Conversion—Converts a time domain waveform to a digital signal with associated timing. The format can be serial or parallel according to specific standard formats such as SPI. This block preferably directly feeds a DIO board. Digital to Analog Conversion—Converts a serial or parallel digital signal to a time domain waveform. The format can be serial or parallel according to specific standard formats such as SPI. This block preferably consumes data acquired using a DIO board. Conversion Blocks—Various blocks for performing conversion operations on signals or scalar values: Add/Remove tags. Convert from/to WDT from/to clusters. Build WDT or cluster from array of scalars. Group/ungroup signals. Thus, in one embodiment, a plurality of function blocks, such as, for example, any of those listed above (or others), may be used in specifying and performing a signal analysis function utilizing a plurality of instruments. In a preferred embodiment, the plurality of instruments includes two or more virtual instruments (VIs), at least a portion of which may include respective hardware components, as mentioned above. Note that in some embodiments, one or more of the function blocks may be polymorphic, e.g., with respect to input signals. For example, a polymorphic function block may accommodate different data types of the input signal provided to the function block, e.g., arithmetic function blocks for addition, averaging, and so forth, may be operable to receive and operate on signal data in the time domain or the frequency domain. In one embodiment, each function block may include: a function block icon operable to be displayed in a graphical user interface (GUI) of a signal analysis function development environment, where the function block icon visually indicates a respective signal operation, and a set of program instructions associated with the function icon, where the set of program instructions are executable to perform the respective signal operation, possibly in conjunction with associated hardware. In one embodiment, each function block may be selectable from the plurality of function blocks by a user for inclusion in a set of function blocks, where each function block operates to perform the respective signal operation continuously upon being selected. For example, the user may select a first function block from a palette, menu, etc., in response to which the respective signal operation may be performed, preferably executing in a continuous manner until, for example, a stopping condition occurs or the user pauses or terminates the process. As described above, the user may then select one or more additional function blocks, which may similarly begin continuous respective operations in conjunction with the first function block. In one embodiment, each function block may be operable to provide a respective output based on the respective signal operation, where the respective output is operable to be displayed in the GUI, provided as input to one or more other ones of the set of function blocks, and/or exported to an external device. In other words, each function block may generate a respective output that may be used as input to or by other function blocks in the set of function blocks, transmitted to an external device coupled to the host computer 82, and/or displayed in a display tool, such as a graph or table, in the GUI. Additionally, one or more of the function blocks may be operable to receive a respective input based on the respective signal operation, where the function block is operable to perform the respective signal operation on the input, e.g., on a signal and/or data, and provide the results as output. In one embodiment, each function block may include an input and an output, where the input is operable to receive signals from one or more of: an external signal source, a file, and/or another function block, and where the output is operable to send resultant signals to one or more of: a display of the GUI, an external device, a file, and/or another, different, function block. Once the user has selected the set of function blocks, the set of function blocks may be executable to perform the signal analysis function under the signal analysis function development environment using one or more of the plurality of instruments. For example, in an embodiment where each function block executes substantially continuously upon selection by the user, when the user is done selecting the function blocks, the signal analysis function (specified and implemented by the set of function blocks) is already being performed. As another example, the user may stop the current execution of the signal analysis function (which was, for example, initiated in steps via the function block selection process), then re-initiate performance of the signal analysis function, thereby invoking execution of the set of function blocks. In another embodiment, information specifying the respective signal operations of the set of function blocks may be saved, e.g., as a script, that may be executed as desired under the signal analysis function development environment. In one embodiment, the set of function blocks may be displayed in a diagram, e.g., in a specified display area of the GUI. The diagram may include one or more of: a linear sequence, a data flow diagram, a tree diagram, and a dependency diagram, among other types of diagram. The diagram may substantially visually represent I/O relationships between the function blocks. For example, where output from a first function block is provided as input to a second function block, this relationship may be graphically represented in the diagram, e.g., via a data flow line from the first function block to the second function block, via I/O signal icons displayed in, on, or proximate to each function block icon, and/or by the relative positions of the function blocks, and so forth. In one embodiment, when the I/O relationships between the function blocks change, the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. Thus, if a user changes an I/O relationship between function blocks, the diagram may be updated automatically to reflect the change. Examples of linear sequence function block diagrams are provided below with reference to FIGS. 6 and 8A-8I. In one embodiment, the diagram may include one or more control structures, where the one or more control structures control execution of the set of function blocks. For example, the one or more control structures may include conditional branching and/or looping, which may determine control or execution flow for performance of the specified operations comprised in the signal analysis function, such control structures being well known in the art of software and script development and execution. Thus, the diagram may comprise or visually represent a script (or equivalent) that is executable to perform the specified signal analysis function under the development environment. Said another way, the diagram may include information specifying the respective signal operations of the set of function blocks, where the information is executable to perform the signal analysis function under the signal analysis function development environment. As described above in the Code Generation section, in one embodiment, the information specifying the respective signal operations of the set of function blocks may be useable to generate a program, where the program is executable to perform the signal analysis function independently of the signal analysis function development environment. In other words, in one embodiment, the signal analysis function development environment may be operable to automatically generate an executable program based on the information specifying the respective signal operations of the set of function blocks, where, in contrast to the diagram and/or script which executes under the environment, the generated program may be executed independently of the development environment. As described above, in various embodiments, the generated program may be a graphical program, such as a LabVIEW graphical program, a text based program, such as a C, C++, JAVA, or Basic program, and/or machine executable code. In one embodiment, each of at least a subset of the plurality of function blocks may be operable to receive a signal (or signal data) from a signal source, perform the respective signal operation on the signal, and output a result of the respective signal operation for display in the GUI, storage, input to another one of the plurality of function blocks and/or export to an external device. Additionally, in one embodiment, the set of program instructions for each function block may be further executable to: receive user input selecting the function block icon, display a configuration GUI for the function block, and receive user input to the configuration GUI setting one or more parameters of the function block, thereby configuring the function block, where the configured function block is operable to perform the signal operation in accordance with the one or more set parameters. In other words, each function block may include or be associated with software (program instructions) that implements a respective configuration GUI for that function block, and that also facilitates user invocation of the configuration GUI, e.g., by receiving user input to the function block (icon). For example, in one embodiment, the user may right-click on the function block icon, thereby invoking the configuration GUI. Alternatively, the user may provide input (e.g., click) on the function block icon to invoke a menu or pop-up dialog from which the configuration GUI itself may be invoked. In yet another embodiment, the initial user selection or specification of the function block may automatically invoke display of the function block's configuration GUI. In one embodiment, each function block may have a default configuration, where, prior to configuring the function block, the function block is operable to perform the signal operation in accordance with the default configuration. In other words, parameters that specify or configure the signal operation of the function block may have default values such that even if the user does not explicitly configure the function block, the function block may still be operable to perform the respective signal operation based on the default values of the parameters. Of course, the user may override these default values as desired. It should be noted that the configuration parameters shown and described with regard to any of the function blocks presented herein are meant to be exemplary only, and are not intended to limit the parameters to any particular set or types of parameters. In one embodiment, at least one of the plurality of function blocks may be a user-defined function block, where the set of program instructions of the user-defined function block are executable to perform a user-defined signal operation. In other words, at least one of the function blocks may include functionality that is defined or specified (as opposed to simply configured) by the user. For example, in one embodiment, the set of program instructions of the user-defined function block nay include a pre-defined program. The pre-defined program may have been developed by the user, by another developer, or may have been developed programmatically by another system. The user may provide input to the development environment and/or to the user-defined function block indicating the pre-defined program, thereby establishing a link between the user-defined function block and the pre-defined program, and/or including the pre-defined program in the function block. Thus, once the user-defined function block has been selected (and optionally configured), and the pre-defined program linked to or included in the function block, the pre-defined program may execute substantially continuously in conjunction with any previously selected function blocks, as described above. As noted above, in a preferred embodiment, each function block may be operable to display respective icons for one or more input signals and/or one or more output signals for the function block. For each function block, the respective icons may include text and/or a graphical image indicating a respective signal for that function block. In additional to indicating respective signals for the function block, these icons may also be used to manipulate, establish associations with, or otherwise manage the signals. For example, each icon of the function block may be selectable by a user to associate the respective signal with a display, i.e., a display tool, of the GUI, where in response to being associated with the display, the respective signal is displayed in the display of the GUI. In one embodiment, in being selectable by a user, each icon may be operable to be dragged and dropped onto the display of the GUI, resulting in display of the respective signal on the display of the GUI. Thus, in one embodiment, the user may drag and drop signals (e.g., signal icons) from function blocks onto the display to invoke graphical display of the signals. Alternatively, or in addition to the above, each icon of the function block may be selectable by the user to associate the respective signal with a different function block of the set of function blocks, where in response to being associated with the different function block, the set of program instructions of the different function block performs the respective signal operation on the respective signal. For example, the user may drag and drop the signal icon onto the different function block, thereby configuring the different function block to receive the respective signal as input and to perform the respective signal operation on the respective signal. Thus, in one embodiment, each function block may be operable to receive user input indicating one or more input signals, where the function block is operable to perform the signal operation on the indicated one or more signals in response to the user input indicating one or more input signals, where, for example, the user input indicating one or more input signals includes the user dragging and dropping one or more signal icons onto the function block. In an embodiment where the display of the GUI includes a graph (or other type of display tool) operable to display one or more signals, the user input indicating one or more input signals may include the user selecting at least one signal in the GUI display, and the user dragging and dropping a corresponding at least one signal icon from the graph onto the function block, where the at least one signal icon represents the at least one signal in the GUI display. Said another way, in one embodiment, signal icons may be displayed and accessed in the graphical display of the GUI, i.e., a display tool of the GUI, where the signal icons may be selected, e.g., via clicking with a mouse, and dragged and dropped onto the desired function block, whereupon the function block may be automatically configured to receive the indicated signal as input. The signal icons may be implemented or displayed in various forms. For example, in one embodiment, the signal icons displayed in the graph may be included in the legend of the graph, e.g., as a symbol, icon, or text label, where the user may select the signal by clicking on the icon in the legend. Alternatively, the signal icon may be displayed in response to the user clicking on the signal plot itself, e.g., in the form of a “pop-up” icon that may then be dragged and dropped on a function block as desired. In a further embodiment, the signal plot itself may be the signal icon, where the user may select the signal plot, then drag and drop the signal plot (i.e., an image of the signal plot) onto the targeted function block. Of course, this same technique may be used to move a signal from one graph to another, as well. Thus, each signal icon may serve as a token, handle, or surrogate for a respective signal whereby the user may establish or modify relationships between the signal and elements of the system, e.g., function blocks, graphical or tabular displays, and so forth. FIG. 6—Example GUI and Environment Overview FIG. 6 is an example of one embodiment of a GUI for specifying, implementing, and/or performing a signal analysis function. More specifically, the GUI provides an interface for the signal analysis function development environment mentioned above. Note that the example shown is meant to be exemplary only, and is not intended to limit the GUI to any particular appearance, form, or functionality. As FIG. 6 shows, the GUI may include an area or window for displaying a plurality of function blocks, here shown as the left-most window of the GUI. The display window may be referred to as a display tool and may comprise a graph or a table as desired. As described above, the displayed function blocks may each correspond to a respective signal operation that has been selected by a user and thus represent the currently specified operations, where each function block has an icon, a label, and icons for input and/or output signals. As shown, in one embodiment, the input and output signal icons for each function block may be displayed in a manner that indicates whether the signal is an input or an output for that block. For example, in the embodiment shown, the signal icons at the bottom of each function block each have a graphical “I/O” icon comprising a vertical line and a triangle, placed either to the upper left of the vertical line, indicating input, or to the lower right of the line, indicating output. Of course, other means of indicating whether a signal is an input or an output for the function block are also contemplated, such as, for example, using labels, e.g., “I” for input and “O” for output, grouping the signals for each block into an input group and an output group, and so forth. The plurality of function blocks are preferably included in a function block diagram, where, as described above, a plurality of function block icons are arranged to visually indicate the signal analysis function. In other words, in one embodiment, a diagram including the function block icons of the specified operations is displayed, where the diagram visually indicates the functionality of the signal analysis function. In various embodiments, the diagram may be one or more of: a linear sequence, a data flow diagram, a tree diagram, and a dependency diagram. Note that in the embodiment of FIG. 6, the function block diagram is presented as a vertical linear sequence of function blocks, where the respective signal operations are performed accordingly, although it should be noted that, as mentioned above, each of the operations is executed in a substantially continuous manner. Thus, the linear sequence may indicate the general data flow between the function blocks. It should also be noted, however, that although the diagram may be presented as a linear sequence, in some embodiments, the I/O relationships between the function blocks may not be linear. For example, non-linear data flow may be specified and indicated via input and output signal icons for the function blocks, as described above. As FIG. 6 also shows, a display area of the GUI may be provided (shown to the right of the function blocks) for displaying signals and related data. As noted above, the display of the GUI may be used to display signal graphs, as well as tabular data, i.e., tables of data. As also shown, a menu or tool bar may be provided along the top of the GUI whereby the user may invoke functionality to control execution of the operations, generate code, set triggers and timing, and so forth. In one embodiment, the tool bar may include an “Execute Continuously” button which may be selected to configure the environment to execute each operation in a substantially continuous manner upon selection of the operation by the user. Note that in this example, the display area or window is tabbed for “Data Viewer” and “Step Setup”, where the graphical display shown is in the Data View mode, here displaying three different graphs, where the middle graph itself includes three signal plots. This mode may be used primarily during execution of the signal analysis function, specifically, to display resultant signals and/or data from one or more of the function block operations. The Step Setup mode may be used primarily during configuration of the respective function blocks. More specifically, the Step Setup mode may operate to display configuration GUIs for the respective function blocks facilitating user configuration of the function blocks, i.e., the signal operations, as described in some detail above. Various examples of configuration GUIs are described below with reference to FIGS. 8A-8I. FIGS. 7-8G—Signal Analysis Function Development Environment: Example Walk-Through FIGS. 7-8G illustrate use of a graphical user interface (GUI) for a signal analysis function development environment, according to various embodiments. More specifically, the GUI shown in these figures illustrates one embodiment of an interface whereby a user may interactively specify (and perform) a signal analysis function according to various embodiments of the method of FIG. 5, described above. In other words, an example walk-through is provided to illustrate one example of the process and to illustrate corresponding aspects of the GUI. FIG. 7 illustrates the hardware setup for the system, and FIGS. 8A-8G are screenshots of the GUI illustrating various steps (and results) in the specification of the signal analysis function. In this example, a Unit Under Test (UUT), specifically an LC-Diode filter circuit, is stimulated with a test signal, and the circuit's response captured and analyzed. As FIG. 7 shows, in this particular example, the system includes a computer monitor 702 and keyboard/mouse 704 coupled to a PCI or PXI chassis 706, where the chassis includes a plurality of boards or cards, including a PC-Controller (e.g., a computer on a card, with a bus, e.g., a PCI or PXI bus) 82A, an analog signal generator (e.g., an NI-5411 Arbitrary Waveform Generator (Arb)) 708, a high speed analog signal digitizer, also referred to as a Scope (e.g., an NI-5112 High Speed Digitizer) 710, and a DAQ board (e.g., an NI-6115 SMIO (Simultaneous-Sampling Multifunction I/O) board) 712, which is another type of analog signal digitizer. Note that in this embodiment, the PC-Controller 82A functions as the host computer for the system. Thus, in this embodiment, substantially all of the hardware for the system other than human interface devices, i.e., the monitor, keyboard, and mouse, is included in a PCI or PXI chassis, including the host computer itself, where each hardware device comprises a PCI or PXI card or board. As FIG. 7 also shows, the Arb 708, the Scope 710, and the DAQ 712 are each coupled to the Unit Under Test 720, in this example, the LC-Diode filter circuit mentioned above, via physical analog connections, e.g., BNC cables are their equivalent. As indicated by the directional connections, the Arb 708 may be operable to send signals to the UUT 720, and the Scope 710 and DAQ 712 may be operable to receive signals from the UUT 720. Of course, each of the other hardware devices or boards is preferably communicatively coupled to the PC-Controller or host computer 82A, whereupon various software programs according to the present invention may be executed, e.g., software portions of VIs, the development environment, and so forth. As mentioned above, FIGS. 8A-8G illustrate a walk-through of an exemplary signal analysis function development session using on embodiment of the GUI. It should be noted that this walk-through assumes that the function blocks have already been selected, but not configured yet (beyond the optional default configuration), and so in the description below, steps are described for interactively configuring the function blocks to perform the desired signal analysis function, i.e., the test of the LC-Diode filter circuit. It should be noted that the original selection or specification of the operations or function blocks would proceed in substantially the same manner, but the user would invoke the operation itself, rather than a configuration panel for the operation. It should be further noted that the embodiments described below are meant to be exemplary only, and are not intended to limit the features or operation of the system to any particular set of features, steps, or mechanisms. In the example shown in FIG. 8A, the function blocks currently specified include a Basic Function function block, an Arbitrary Generator (type or model 5411) function block, corresponding to the Arb board 708 of FIG. 7, a Scope Acquire Signals function block corresponding to the Scope 710, a DC-RMS function block, and a Distortion function block, each of which is described in more detail below. As noted above, in some embodiments, the GUI may include an “Execute Continuously” button which may be selected to configure the environment to execute each operation in a substantially continuous manner upon selection of the operation by the user, and so initially the user may activate this feature by pressing the button. FIG. 8A illustrates signal specification and creation using the Basic Function block, where the user may initiate creation of the signal by first selecting the Basic Function block, e.g., by clicking on the Basic Function block with a mouse, via a top-level menu of the GUI, or, in one embodiment, via a context-menu in the function block display window or section of the GUI. The user may then invoke a configuration GUI for the Basic Function block, shown in the display section of the GUI, e.g., by right-clicking or double-clicking on the function block or otherwise invoking the configuration GUI for the Basic Function block. For example, the user may right-click on the function block to invoke an options menu for the function block, then select a “Configure” option (or equivalent) to invoke the configuration GUI. In the embodiment shown, the configuration GUI for the Basic Function block includes a number of fields or controls for specifying the waveform to be output by the Basic Function block, e.g., signal type, here selected to be a “Sine Wave”, amplitude (1.00000), frequency (10 KHz), offset(V) (0.000), and phase(deg.) (0.000), provided in a “Basic Function Setup” section. Additional controls may be provided in a “Sampling Conditions” section for sample rate(Hz) (1 MHz) and block size(samples) (1000), as well as a check box for a “Reset at run” option. Note that in one embodiment, the configuration GUI may be tabbed as shown to provide a configuration panel (with the above controls) displayed by user selection of a “Configuration” tab, and an “Output Signals” panel (not shown selected) displayed by user selection of an “Output Signals” tab, which may be operable to indicate the current output signals of the function block, e.g., via name and/or icon. In this embodiment, the configuration GUI also includes a display area for displaying signals related to the selected function block, here shown displaying the specified sine output signal. Note also that in this embodiment, two tabs are provided at the bottom of the display section, titled “Step Setup” and “Data View”, facilitating user selection between a configuration mode and a display mode, as described above with reference to FIG. 6. As FIG. 8A shows, the “Step Setup” tab is currently selected for the configuration process described herein. Once the Basic Function operation has been configured, the specified signal (sine wave) data may be generated, e.g. algorithmically or read from file. This signal data is output substantially continuously by the configured function block. Turning now to FIG. 8B, the next function block in the diagram is shown selected, specifically, the 5411 Arbitrary Generator function block, operable to receive specified signal data, e.g., the “basic function 1” signal data, as input and generate a corresponding analog signal based on the signal data (e.g., utilizing an arbitrary waveform generator board). In one embodiment, the user may specify this relationship between the Arbitrary Generator function block and the signal data by right-clicking on the “basic function 1” signal (plot, legend, or label) in the graph, thereby invoking a menu of options from which the user may select a “Generate Signal with the Arb” signal operation option (or its equivalent). Alternatively, the user may right-click or otherwise select the “basic function 1” output signal icon displayed by the Basic Function block (labeled “basic function 1”) to invoke the signal operation options. In one embodiment, the menus invoked via signals or signal icons may be context-sensitive menus that only display options that are appropriate for the signal or data type of the indicated signal. Other means of invoking the operation options for the signal data are also contemplated. As FIG. 8B shows, once the user has specified this I/O relationship between the signal data and the Arbitrary Generator function block, an input signal icon (labeled “basic function 1”) may be displayed by the Arbitrary Generator function block, indicating that the Arbitrary Generator function block is configured to receive the signal data from the Basic Function block and generate an analog signal based on the signal data. As FIG. 8B also shows, the specification of the Arbitrary Generator function block may invoke a configuration GUI for the Arbitrary Generator function block, here shown in the tabbed section labeled “Configuration”. The configuration GUI for the Arbitrary Generator may provide one or more GUI elements for specifying and displaying various parameters for the arbitrary waveform generation functionality of the Arbitrary Generator function block, e.g., hardware configuration parameters such as, for example, a device specification (shown as Dev6: PXI-5411), a channel name, sample rate (set to 1 MHz), Gain (set to 1), Offset (set to 0.0), a filter toggle, and an input data or signal designation (set to “basic function 1”). In one embodiment, one or more of the parameters may have default values which may be overridden by the user as desired. In the example shown, the graph section of the GUI (above the configuration section) may operate to display the generated signal, where the graph is labeled accordingly (“Generated Signal”). Thus, the GUI may provide means for configuring the operation, as well as for displaying the results of the specified configuration. In one embodiment, the GUI may automatically display the output signal or signals from the currently selected function block, such that when a new or different function block is selected, any previously displayed signal graph may be replaced or supplanted by the new or different signal graph. In another embodiment, each successive function block specification may result in the display of an additional signal graph. For example, each signal graph may be displayed in a separate window, where the windows may be tiled, cascaded, or otherwise organized for viewing by the user. Alternatively, the signal graphs may be displayed in a single window. In one embodiment, a different graph may be used to display each basic type of signal. For example, time domain plots may be displayed in a first graph, while frequency domain plots may be displayed in a second graph. In one embodiment, tabular data may be displayed separately, e.g., in a different display window or section of the GUI. In FIG. 8C, the third function block (SCOPE Acquire Signals) in the diagram is shown selected. This function block may be operable to acquire a signal from a specified source via a digitizer or “scope” card, such as the Scope 710, and provide the signal as output on a specified channel (here shown as Channel0). In other words, the SCOPE Acquire Signals function block may provide means for acquiring a signal, e.g., from an external signal source or from other hardware comprised in the host system, and outputting the acquired signal for use by other function blocks and/or display. Similar to the above described function block, in one embodiment, the function block may be configured in the following manner: The user may invoke an operations options menu from the “generated signal” plot above, e.g., by right-clicking in the signal area (or on the signal plot, legend, or signal icon, e.g., in the graph or on the function block), to invoke an options menu, and selecting an “Acquire Analog Signal with the Digitizer” option (or its equivalent), resulting in display of a configuration GUI for the SCOPE Acquire Signals function block. In the embodiment shown, the SCOPE Acquire Signals function block is configured to acquire the analog signal generated by the Arb described above. As FIG. 8C shows, in this example, the configuration GUI includes three panels, tabbed and labeled “Configuration”, “Triggers and Timing”, and “Output Signals”, respectively, where the Configuration panel is shown active or displayed. As described above, the Configuration panel may include one or more GUI elements for specifying and displaying various parameters for the functionality of the corresponding function block. For example, the Configuration panel for the SCOPE Acquire Signals function block may include hardware configuration parameters such as, for example, a device specification (shown as Dev8: PXI-5112), a channel specification, and a mode designation (set to “Acquire N Samples). As shown, the Configuration panel may also include fields for specifying Vertical and Horizontal Configuration of the acquired signal, such as, for example, Minimum (−1) and Maximum Range (1), Probe Attenuation (1.0), Input Impedance (1 MOhm), an AC Coupled option, as well as sample rate (set to 1 MHz) and Record Length (set to 1000 points). As described above, the Output Signals panel (not shown) may be operable to indicate the current output signal(s) of the function block, e.g., via name and/or icon, i.e., “ChannelO”, in this case. Details of the Triggers and Timing panel are described below with reference to FIG. 8D. Note that this Configuration GUI also includes a signal graph display of the acquired signals, here labeled “Acquired Signals”. Thus, the user may view the signal or signals acquired by the digitizer from the arbitrary waveform generator. As noted above, in one embodiment, multiple signals may be specified for display in the graph display area or window. For example, in one embodiment, the user may select and drag both signals “Channel0” and “basic function 1” to the graph display (the GUI's main graphical display in the “Data View” mode, as shown in FIG. 6 and described above), where the two signals may be overlaid in the same graph, e.g., for easy comparison, or respectively displayed in separate graphs as desired. Note that the acquired signal “Channel0” of FIG. 8C is not currently triggered, and so triggering and timing parameters may need to be specified for the signal or operation. FIG. 8D illustrates one embodiment of the Triggering and Timing panel of the configuration GUI of FIG. 8C, whereby such parameters may be set. As FIG. 8D shows, in this example, the Triggers and Timing Panel may itself comprise multiple panels, namely “Reference Trigger”, “Start Trigger”, and “Advanced Timing” sub-panels. As shown, the Reference Trigger panel includes GUI elements for specifying and displaying Trigger Type (set to “Edge”), Analog Trigger Channel (set to 0), Trigger Holdoff (0.000), Pretrigger Samples (0), Trigger Slope (positive), Trigger Delay (0.000), Trigger Level (0.00), and Trigger Coupling (DC). Similar triggering parameters may be specified for the Start Trigger in the Start Trigger sub-panel (not shown). In one embodiment, triggers and timing signals may be shared between boards (e.g., hardware components of the VIs) in the system, facilitating easy synchronization between devices and processes. FIG. 8E illustrates addition of a second data acquisition function block, specifically, an “SMIO Acquire Signal” function block, which may be operable to acquire further data via another type of analog signal digitizer, e.g., the NI-6115 SMIO (Simultaneous-Sampling Multifunction I/O) board 712. For example, in one embodiment, the user may have invoked the corresponding SMIO Acquire Signal operation via a pop-up menu from the tool bar, right-clicking in the function block display area of the GUI, or by other means, resulting in the addition of the SMIO Acquire Signal function block in the diagram. As noted above, the function block's configuration GUI may be invoked and displayed automatically upon selection of the function block, or may be invoked explicitly by the user via interaction with the function block, as described above. Similar to the SCOPE Acquire Signals function block example above, the SMIO Acquire Signal configuration GUI may provide one or more panels for configuring and displaying parameters regarding Configuration, Triggers and Timing, and Output Signals. As shown, in this example, the Configuration panel includes a Device field (set to Dev4: PXI-6115/ai), a Channel Configuration section with fields for Physical Channels (ai0), Input Range (ai0 max value (−0.5) and ai0 min value (−0.5)) and an a0 filter option (none), as well as an Acquisition Timing section whereby sampling specifications may be set, e.g., Acquire 1 or N Samples or Acquire Continuously, Samples to Read (2000), and Sample Rate(Hz) (200.00 k). Other configuration panels, e.g., the Trigger and Timing panel and the Output Signals panel may provide access to other configuration parameters related to those areas of the respective signal operation, as described above. For example, in one embodiment, the user may configure the SMIO Acquire Signal function block (signal operation) to trigger based on a reference trigger from the SCOPE Acquire Signals hardware component, i.e., the Scope 710. The reference trigger may be a digital signal routed on the backplane of the PXI or PCI chassis. Thus, as noted above, timing and triggering signals may be shared between boards (e.g., hardware components of the VIs) in the system. As FIG. 8E also shows, in this example, the configuration GUI also may be operable to display the acquired signals, here labeled “Acquired Signals” in the graph display of the configuration GUI. Note that in this embodiment, the graph includes an option for autoscaling the amplitude of the signal plot (top right of graphical display). As the inclusion of the SMIO Acquire Signal function block in FIG. 8E was specifically to illustrate shared triggering between signal operations, the function block is not needed for the remainder of the walk-through, and so may be deleted, e.g., by right-clicking on the function block in invoke a menu, and selecting “Delete” (or equivalent). Alternatively, in one embodiment, the user may simply click on the function block and hit the “delete” key on the keyboard, whereupon the function block may be removed from the diagram. While the above-described function blocks related to generation or acquisition of signals, other function blocks may be invoked and configured to perform analysis functions on the generated and/or acquired signals. FIG. 8F illustrates configuration of an analysis function block, specifically, the DC-RMS function block. The DC-RMS function block may operate to receive the Channel0 output signal from the SCOPE Acquire Signal function block, and compute scalar values for a DC (direct current) level and RMS (root mean square) for the signal. As FIG. 8F shows, in this embodiment, the configuration GUI displays the Channel0 signal in the graph display, labeled “Input Signal”. Note that there is some distortion in the negative peaks (troughs) of the signal (rounding of the bottom peaks) caused by the filter under test. As FIG. 8F also shows, the configuration GUI for this function block includes panels or sections with fields for specifying parameter values for the DC and RMS computations, e.g., a Measurement Setup section that includes fields for “Averaging Type” (set to linear), and “Window” (set to Rectangular), as well as an Input/Output Configuration section for setting and/or indicating Input Data (Channel0), and outputs, e.g., Output: (dc 1) and Output 2: (rms 1). In this embodiment, the configuration GUI also includes a Measurement Results section that displays the computed results, i.e., a DC Value (51.6706 m) and an RMS Value (641.35 m), as well as controls for setting scaling values for the displayed results. Thus, in some embodiments, the configuration GUI may display both the input signal(s) and output(s) (results) for a function block. For example, if both the inputs and the outputs of a function block were signal waveforms, the configuration GUI may display both the input and the output signals in the graph display of the configuration GUI, either separately or together in a single graph as appropriate. Note that in the Data View mode for the environment GUI, such scalar results are preferably displayed in tabular form, e.g., in the form of a spreadsheet, as opposed to a signal plot or graph. FIG. 8G illustrates configuration and use of another example analysis function block, specifically, a Distortion analysis function block, operable to measure and analyze distortion for an input signal, in this case, the Channel0 signal. As described above, a configuration GUI for the Distortion function block may be invoked by the user, e.g., by right-clicking on the Channel0 signal or signal icon and selecting “Distortion” from a pop-up context-sensitive menu. As FIG. 8G shows, the configuration GUI for the Distortion function block may include various panels and sections for specifying and displaying configuration parameters for the distortion analysis. For example, an Input/Output Signals configuration panel may include fields specifying and/or indicating the input signal(s) and resulting output signal(s) for the block. This information may also be indicated by the signal icons displayed by the function block itself, where in this case, the input signal is specified as “Channel0”, and the output signals include “exported time signal 1”, “exported spectrum 1”, “fundamental frequency 1”, “distortion 1”, “SINAD 1”, and “Harmonics 1”, any of which may be displayed by the configuration GUI and/or the main display of the environment. As shown, the configuration GUI shown in FIG. 8G for the Distortion function block also includes a Configuration panel for specifying various parameters for the analysis, e.g., a Measurement Setup section with fields such as “distortion type” (here set to Harmonic Only), Highest Harmonic (19), Export Signals(THD) (set to input signal), and an index list indicator, as well as a Measurement Results section with fields such as, for example, Detected Frequency(Hz) (9.999992 k), THD (105.5 m), and Harmonics (78.89 m). Note that in this example configuration GUI, three types of data displays are used: scalar data are displayed numerically in the Measurement Results section, the Exported Signal is displayed in a time-domain graph (top graph), and a Power Spectrum for the Exported Signal is displayed in a frequency-domain graph (bottom graph). In a Data View mode of the environment GUI, these data may be displayed similarly, although the scalar data is preferably displayed in tabular form (instead of numeric fields), e.g., in the form of a spreadsheet-like scalar table. For example, as described above, in one embodiment, the user may drag signal icons for the exported signal (exported signal 1) and the exported spectrum (exported spectrum 1) from the Distortion function block onto the main display of the environment GUI, thereby invoking display of the two graphs, where the particular form of the graph may be dependent upon the signal type, e.g., time-domain vs. frequency domain. The user may also drag the distortion signal icon (distortion 1) from the Distortion function block onto the main display, invoking automatic generation and display of a spreadsheet-like scalar table for the scalar data. Thus, the particular form of the display for a specified signal or data may be automatically determined based on the signal or data type of the displayed information. FIGS. 8H and 8I—Further Examples of Function Blocks FIGS. 8H and 8I illustrates further examples of function blocks and their use, according to one embodiment. As noted above, the function blocks shown and described herein are meant to be exemplary only, and are not intended to limit the function blocks or their use to any particular function or form. FIG. 8H illustrates a Graph Align function block that implements a signal alignment tool. In the embodiment shown, this tool allows the user to align two signals with each other. As described above, based on the selected (or just added) function block, the GUI may provide various display and/or configuration elements or panels in accordance with the function block. In the embodiment shown, alignment may be performed manually or automatically. For example, the manual approach may allow the user to adjust the offset and gain of the signals by selecting a point in the graph and moving the cursor. In contrast, the automatic method may use an algorithm and the expected type of waveform (e.g., impulse/step/periodic) to perform the alignment. In either case, the offset and gain values that result in a substantial alignment of the signals are preferably returned or displayed to the user. As FIG. 8H shows, in this embodiment, two input signals, “Channel0”, provided by the Scope Acquire Signal function block described above, and “imported signal 1”, provided by an Import Simulation function block in the function sequence shown, are displayed in an upper graph display of the GUI, labeled “Input Signals”. As indicated by the Graph Align function block, the two signals are received as input to the function block and a “resulting signal 1” provided as output, here shown in a lower graph display of the GUI, labeled “Comparison Result Signal”. As shown, in this embodiment, the GUI includes various tabbed configuration panels for specifying the signal alignment, including alignment conditions such as mode, shown set to “Manual”, and geometry parameters for setting gain and offsets for the signals to effect the alignment, which may be set using the spinner controls and/or check boxes shown. In one embodiment, the user may also modify the parameters directly by entering a numeric value. As FIG. 8H also shows, in some embodiments, additional configuration panels may facilitate further operations or configuration, including, for example, re-sampling of one or more of the signals. Thus, the Graph Align function block may be included in the function sequence, and configured to facilitate manual or automatic alignment of two or more signals, thereby providing further means for characterizing or analyzing signals. FIG. 8I illustrates various other example signal analysis function blocks and their use in an example test sequence. As FIG. 8I shows, in this embodiment, the test sequence includes a “Multisine Signal” function block that operates to provide sine wave signal data, the Arbitrary Generator (type or model 5411) function block described above, operable to receive the sine wave signal data and generate a signal “multisine 1”, an SMIO Acquire Signals function block for acquiring and providing analog input signals Dev4\ai0 and Dev4\ai1 (e.g., from Device 4), a Dual Channel Spectrum function block, operable to receive the Dev4\ai0 and Dev4\ai1 signals and output magnitude and phase signal information (magnitude 1 and phase 1) for the signals, an Import Simulation function block, operable to provide an imported simulation-generated signal “imported signal 1”, an arithmetic function block, operable to receive the magnitude 1 and imported signal 1, and output a resulting signal, in this case, “resulting signal 1”. Finally, the signal “resulting signal 1” is provide to a Limit Test function block (according to one embodiment), which performs a limit test on the signal, illustrated graphically in a graphical display of the GUI labeled “Limit Test”. As FIG. 8I shows, in this embodiment, the Limit Test function block outputs various signals and/or data, including a “passed 1” signal, “signal out 1”, “failed signal 1”, “upper limit 1”, “lower limit 1”, and a “Limit Test Result 1” signal, indicating specifics of the test and its results. As FIG. 8I also shows, in this embodiment, the GUI includes a configuration panel whereby the user may specify or determine a “Limit Specs” file for specifying various aspects of the limit test, and which also displays a visual or graphical indicator of whether the test was passed or failed, labeled “Passed?”. As illustrated in the graphical display, in this particular example, the signal has violated the limits, and so has failed the limit test. Thus, various function blocks may be defined and used to perform any of a variety of analyses, operations, and tests, using embodiments of the systems and methods described herein. FIG. 9—Data Flow Diagram for the System of FIGS. 8A-8G FIG. 9 is an example data flow diagram for the example system and process described above with reference to FIGS. 7-8G, according to one embodiment. More specifically, FIG. 9 illustrates the flow of data and/or signals in terms of the function blocks specified and configured above. It should be noted that the data flow diagram shown is exemplary only, and is not intended to limit the invention to any particular form, organization, operations, or functionality. In this example, Basic Function function block 902 couples to 5411 Arbitrary Waveform Generator 904, which in turn couples to Unit Under Test (UUT) 906, i.e., the LC-Diode Filter mentioned above. The UUT 906 further couples to Scope Acquire (digitizer) 908, which also couples to DC-RMS function block 910 and Distortion function block 912. In the embodiment shown, the Scope Acquire 908 also couples to Measurement Display System 914, e.g., the graphical display of the GUI. Note that in this example, the UUT 906 and the Measurement System Display 914 are not function blocks, but rather respectively comprise hardware coupled to the host computer 82, and a graph or display window of the GUI, while the other blocks shown represent exemplary function blocks, as described above. As FIG. 9 shows, the Basic Function function block 902 operates to generate a computed “analog” signal 901, i.e., digital data that describes a desired analog signal, here shown provided to the 5411 Arbitrary Waveform Generator 904. As described above, the Arb 904 may operate to receive the computed “analog” signal 901 and generate a physical analog signal 903A, i.e., the actual analog signal specified or represented by the computed “analog” signal 901, providing the generated physical analog signal 903A to the UUT 906, e.g., as a test signal for the LC-Diode filter. As FIG. 9 also shows, the UUT 906 processes (filters) the physical analog signal 903A and produces a resultant (filtered) physical analog signal 903B as output. The physical analog signal 903B is then shown provided to the Scope Acquire (digitizer) function block 908 as input. The Scope Acquire (digitizer) may operate to digitize the physical analog signal 903B and may generate acquired “analog” data 905 comprising the digitized signal. Note that the Scope Acquire function block 908 represents a VI which in this example includes both a software portion (e.g., a graphical program) and a hardware component, e.g., a “scope” card coupled to the host computer 82. Thus, the Scope Acquire VI operates to acquire the physical analog signal 903B, and, as shown, may provide the acquired “analog” data 905 to two additional function blocks, namely, DC-RMS function block 910 and Distortion function block 912, each of which may perform a respective analysis function on the acquired “analog” data 905, as described above. Note that as shown, the Scope Acquire function block 908 may also provide the acquired “analog” data 905 to the Measurement System Display 914 for graphical display of the data. In other words, in addition to providing the acquired data 905 as input to the two analysis function blocks 910 and 912, the Scope Acquire function block 908 also provides the data 905 to a visualization component of the GUI, i.e., a graph, for viewing by the user. It should be noted that this particular I/O relationship (between the Scope Acquire function block 908 and the Measurement System Display 914) is exemplary only, and that in alternate embodiments, the acquired data 905 may be processed first by one or more analysis function blocks, e.g., by one or both of the DC-RMS function block 910 and Distortion function block 912, and then provided to the Measurement System Display 914 for graphical presentation. In other words, rather than providing the acquired data 905 directly to the Measurement System Display 914, the Scope Acquire function block 908 may provide the acquired data 905 to one or more analysis function blocks, which may process or operate on the data and then provide the processed data to the Measurement System Display 914. Thus, the system may perform a specified signal analysis function in accordance with I/O relationships specified by the user between user-specified function blocks, a UUT, and the GUI. It should be noted that more complex systems and processes may also be implemented, where, for example, a plurality of UUTs and/or a plurality of VIs and additional hardware devices, e.g., standalone instruments, may couple to a variety of function blocks, and where the system operates to perform a complex signal analysis function on one or more signals and graphically display one or more results. It should be noted that in some embodiments, the details of the configuration GUI for a function block may change automatically based on the input and output signals for the block, or may be modified explicitly by the user. It should be further noted that in some embodiments, any of the function blocks may be added, removed, and/or modified at edit time and/or at runtime. FIG. 10—Automatic Configuration of Function Blocks In one embodiment of the present invention, input and/or output sources for a selected function block (signal operation) may be automatically selected by the system, e.g., based on heuristics or other rules. In other words, in embodiments where each signal operation is comprised in or associated with a respective function block, when a first function block is selected by the user that requires an input signal of a certain type, the system may attempt to programmatically determine a prior selected function block that provides as output a signal of that type, and may automatically assign that signal/function block as the input for the first function block. FIG. 10 is a flowchart of one embodiment of a method for specifying a signal analysis operation. More specifically, FIG. 10 flowcharts one embodiment of a method for programmatic (automatic) configuration of a function block. It should be noted that in various embodiments, some of the steps shown may be performed concurrently, in a different order than shown, or omitted. Additional steps may also be performed as desired. As FIG. 10 shows, in 1002, user input specifying a first operation may be received, where the operation implements at least a portion of a signal analysis function. In other words, the user may select or invoke a signal operation as described above with reference to FIG. 5, e.g., by right-clicking on a prior function block, signal plot or signal icon, thereby invoking a menu, or otherwise invoking presentation of selectable operations, and selecting the first operation therefrom. Then, in 1004, prior operations input by the user may be programmatically analyzed to determine an input source for the first operation, where the input source provides a first input signal. In other words, operations that have already been specified previously by the user may be analyzed to find an operation that provides an output signal suitable for use as input to the first operation. For example, in one embodiment, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, and determining a prior operation of the prior operations that provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, where the prior operation includes the input source, and where the output signal includes the first input signal. In some embodiments, the first operation may require a plurality of inputs, and so programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more inputs required for the first operation and respective data types of each of the one or more inputs, and determining one or more prior operations of the prior operations that provide respective output signals of the respective data types, where the one or more prior operations include the input source, and where the respective output signals include the first input signal. In one embodiment, the method may also include assigning the output signal (or signals) of the appropriate signal type to the first operation as the first input signal. Said another way, once an output signal has been determined that is of the appropriate type, then the first operation may be configured to receive the determined output signal (or signals) as input. As noted above, in one embodiment, the first operation may correspond to a first function block. In this case, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may include querying the first function block to determine the one or more appropriate signal types for the first operation. Similarly, where the first operation requires a plurality of input signals, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may also include querying the first function block to determine a number of inputs required for the first operation, and programmatically analyzing prior operations input by the user to determine a plurality of input sources for the first operation corresponding to the number of input signals required for the first operation. In another embodiment, determining a prior operation of the prior operations that provides an output signal of the appropriate signal type may include querying a database to determine the prior operation that provides an output signal of the appropriate signal type, where the database includes information indicating respective output signal types of the prior operations. It should be noted that in various embodiments, the database may be stored and accessed on the host computer 82, or on a computer coupled to the host computer 82, e.g., over a network, such as, for example, the Internet. In one embodiment, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include analyzing input/output (I/O) dependencies among the prior operations and the first operation, where the I/O dependencies indicate a proximity ordering of the prior operations with respect to the first operation, and then querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may include analyzing the prior operations regarding input signal types and sources, and output signal types and sources for the prior operations and the first operation to determine an ordering of the operations (proximity ordering) based on the input and output dependencies of the operations, where, for example, each operation is considered adjacent to another if the output of one is the input of the other. Thus, in one embodiment, the proximity ordering may reflect or correspond to a breadth first traversal of a dependency graph (in a computer science theoretic sense) for the set of operations. In an embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type further may include, for each of the plurality of input signals, querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may iterate through the plurality of input signals for the first operation, and for each input signal, analyze the prior operations according to the proximity ordering to determine the prior operation (if any) that produces an output signal of the same type as (or a type compatible with) the input signal. In another embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include iteratively querying the database regarding each of the prior operations to determine one or more prior operations that provide respective output signals of each of the respective signal types, based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as prior operations are found that provide respective output signals of the respective signal types or when there are no further prior operations to consider. In other words, the method may iterate over the prior operations according to the proximity ordering, querying the database regarding each operation and comparing the output signal (or signals) from the operation to determine whether the output signal is of the same as, or a compatible type with, any of the input signals of the first operation. As noted, in a preferred embodiment, the method may stop searching for an input source for a particular input signal of the first operation as soon an input source is found that provides an output signal of the appropriate type. Thus, an input source (or input sources) may be determined that provides signals suitable for input to the first operation. In 1006, the first operation may be performed on the first input signal received from the input source, thereby producing an output signal. As mentioned above, in a preferred embodiment, the first operation may be performed in a substantially continuous manner, thus, the first operation may (in continuous fashion) process signals from the determine input source and generate corresponding output signals. In response to performing the first operation in 1006, in one embodiment, the output signal may be displayed on a display, e.g., in a GUI displayed by a display device such as a computer monitor, as indicated in 1008. For example, as described above, the output signal may be displayed in the display section of the GUI as a signal plot or graph, as tabular data, e.g., in a spreadsheet type format, and/or via other information display means, such as, for example, software-implemented indicators, e.g., gauges, meters, digital displays, and so forth. As indicated in 1010, the method may determine whether there are additional operations to be specified by the user, e.g., based on user input, and, if no further operations are to be specified, the method may terminate, as indicated in 1020. If the method determines that further operations are to be specified, then the method may continue with step 1002 and proceed as described above, where the programmatically analyzing, performing, and displaying may be performed for each of a plurality of first operations input by the user. In one embodiment, if none of the prior operations provides an output signal of the appropriate type, the method may facilitate selection of a different operation by the user as a signal source for the first operation. For example, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, determining whether any prior operation of the prior operations provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, and, if any prior operation of the prior operations provides an output signal of an appropriate signal type, assigning the output signal of the appropriate signal type to the first operation as the first input signal, as described above. If no prior operations provide an output signal of an appropriate signal type, then one or more additional operations that provide an output signal of the appropriate signal type may be displayed, and additional user input received selecting an additional operation from the additional operations, where the additional operation includes the input source for the first operation, and where the output signal of the additional operation includes the first input signal. In other words, if a suitable prior operation cannot be found, additional operations may be presented to the user for selection, where the additional operations each preferably provide an output signal of the appropriate type for use as input to the first operation. Said another way, if no prior operation provides an output signal that is suitable for use as input by the first operation, the method may determine one or more other operations that provide a signal suitable for input to the first operation (e.g., that have not been previously included or selected by the user), and present these one or more other operations to the user for selection. For example, the one or more other operations may be presented in a palette, as options in a menu or dialog, or by any other means, as is well known in the art. In a preferred embodiment, upon selection (by the user) of an additional operation, the method may further include programmatically analyzing prior operations input by the user to determine an input source for the additional operation, where the input source provides an additional input signal, and performing the additional operation on the additional input signal received from the input source, thereby producing an additional output signal. In other words, once the additional (the other) operation is selected by the user, the method may attempt to automatically determine an input signal source for the additional operation, as described above with respect to the first operation. As mentioned above, in a preferred embodiment, the first operation and the prior operations each correspond to a respective function block. In one embodiment, the method may further include receiving user input modifying a configuration of a first function block, thereby changing input signal specifications for a corresponding operation, where original input signal specifications for the corresponding operation specify a first input signal type for the corresponding operation, and where the changed input signal specifications specify a second, different, input signal type for the corresponding operation. In other words, once one or more operations have been specified by the user, resulting in a corresponding one or more function blocks being displayed in the GUI (and the performance of the one or more operations), the user may provide input modifying one or more parameters for one of the function blocks, where the corresponding operation functions in accordance with the one or more parameters, and where the modified function block and corresponding operation require an input signal of the second, different, input signal type. Prior operations input by the user may then be programmatically analyzed to determine an input source for the corresponding operation, where the input source provides the second input signal of the second, different, input signal type, and the corresponding operation performed on the second input signal received from the input source for the corresponding operation, thereby producing a corresponding output signal. In one embodiment, the respective function blocks may be displayed in a diagram that visually represents I/O relationships between the function blocks, as described in some detail above. In one embodiment, when the I/O relationships between the function blocks change (e.g., as a result of modifying one or more of the function block/operation configurations, the addition or removal of an operation, etc.), the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. For example, if the user modifies a function block/operation to receive a different type of input signal than was originally specified, and the method automatically determines an assigns a different input signal source (i.e., a different function block) than currently specified (replacing the original input source for that function block), the diagram may be automatically updated to reflect the new configuration of or I/O relationships between the function blocks. The techniques described above with respect to input signals for the first operation or function block may also be applied with respect to output signals. For example, in an embodiment where the first operation and each of the prior operations corresponds to a respective function block, the method may also include receiving user input modifying a configuration of a first function block, thereby changing output signal specifications for a corresponding operation, where original output signal specifications for the corresponding operation specify a first output signal type for the corresponding operation, and where the changed output signal specifications specify a second, different, output signal type for the corresponding operation. The prior operations input by the user may be programmatically analyzed to determine one or more function blocks configured to receive an output signal of the first function block according to the original output signal specifications, and if the one or more function blocks are configurable to receive the output signal according to the changed output signal specifications, the one or more function blocks may be configured to receive the output signal according to the changed output signal specifications. In one embodiment, if the one or more function blocks are not configurable to receive the output signal according to the changed output signal specifications, for each respective function block of the one or more function blocks, prior operations input by the user may be programmatically analyzed to determine an input source for the respective function block (e.g., to replace the original or current specified input signal), where the input source provides a respective input signal, and the corresponding operation of the respective function block performed on the respective input signal received from the input source, where said performing produces a respective output signal. In other words, if a function block or operation is modified to output a different type of signal (instead of the type originally or previously specified), then any function blocks that are currently configured to receive an input signal of the original type may require a different input signal source to provide an input signal of the appropriate type (e.g., of the original type or of a type compatible with the original type), and so the prior operations may be analyzed to determine suitable input signal sources for the function blocks. Similar to the above, once the results of the modifications have been propagated through the function blocks, the function block diagram is preferably updated automatically to reflect any changes in the I/O relationships between the function blocks. Thus, various embodiments of the systems and methods described above may operate to automatically determine input signal sources for selected function blocks or operations, thereby determining and/or modifying I/O relationships between the function blocks or operations, and optionally, to automatically update a function block diagram to reflect the I/O relationships. FIGS. 11A-13E—Sweep Manager In many signal analysis applications, e.g., device testing, values of one or more parameters may be varied during iterative performance of a function to characterize the UUT over a range of conditions, referred to as a parameter sweep or simply a sweep. For example, a signal analysis function may include one or more signal operations that may be specified for inclusion in a sweep, i.e., in a sweep loop. In one embodiment, a GUI, e.g., the signal analysis function development environment GUI described above, may be provided that facilitates user specification of a sweep as part of a signal analysis function. FIGS. 11A-13E illustrate various embodiments of such a GUI and a method of use. The sweep-related functionality described below may be referred to as a sweep manager, where in various embodiments, the sweep manager may include a plurality of dialogs, menus, or other GUI elements, etc., e.g., in the form of a wizard or a graphical application program interface (API), whereby the user may interactively specify (and optionally perform) a sweep. It should be noted that the embodiments shown are intended to be exemplary only, and are not intended to limit the sweep manager to any particular functionality or appearance. FIG. 11A is a flowchart diagram of a computer-implemented method for specifying and performing a sweep, e.g., in a signal analysis function, according to one embodiment. FIG. 11B is a more detailed flowchart diagram of another embodiment of the method of FIG. 11A. FIGS. 12A-13E illustrate embodiments of a GUI whereby a user may specify the sweep as part of the signal analysis function. More specifically, FIGS. 12A-12D illustrate an embodiment of the GUI in the form of a wizard whereby the user may specify the sweep by navigating through a sequence of dialogs. FIGS. 13A-13E illustrate an embodiment of the GUI in which various configuration dialogs are invoked by the user to specify the sweep. It should be noted that in various embodiments, some of the steps shown in FIGS. 11A and 11B and described below may be performed concurrently, in a different order than shown, or omitted. Additional steps may also be performed as desired. As shown, this method may operate as follows. As FIG. 11A shows, in 1102, first user input indicating a parameter for a first operation may be received, where the operation implements at least a portion of a signal analysis function. Receiving the first user input indicating the parameter for the first operation may be performed in a variety of different ways. For example, the user may provide the name of the parameter (and/or the first operation) to a text entry field, or may invoke display of parameters for the first operation, and select the desired parameter, e.g., with a pointing device, such as a mouse. Other means of receiving user input indicating the parameter are also contemplated. FIG. 12A illustrates one embodiment of a GUI that may operate to display the parameters (e.g., sweepable parameters) of the first operation, and may further operate to receive the first user input indicating the parameter to be swept on. The GUI may be invoked by any of various means, e.g., by right-clicking on the function block of the first operation (in this particular example, the Basic Function function block) to invoke an options menu, and selecting a “Sweep Manager” option (or equivalent). As another example, the user may invoke the sweep manager from a menu in the development environment, and provide input indicating the first operation and/or the parameter. Other means of invoking the GUI are also contemplated. As FIG. 12A shows, the GUI preferably includes a display of sweepable parameters for the first operation. In this embodiment, a dialog including a tree diagram is provided for displaying the parameters, where the parameters are each selectable with a pointing device, e.g., a mouse. Thus, the GUI may receive the user input indicating the parameter. In one embodiment, an indication that the parameter has been selected may be provided by the GUI. For example, in one embodiment the name of the selected parameter may be highlighted, as is well known in the art. Note that in the embodiment shown, “Back”, “Next”, “Finish”, and “Cancel”buttons are provided for navigating through the sweep specification process. In other words, as noted above, the GUI presented in FIGS. 12A-12D is in the form of a wizard, whereby the user is guided through the sweep specification process via a plurality (sequence) of dialogs or panels. In 1104, the first operation may be programmatically or automatically included in a sweep loop. In other words, the operation corresponding to the selected parameter may be included in the sweep, such that when the signal analysis function is performed, the first operation may be executed in the sweep, where the first operation is performed iteratively as the parameter is varied. Note that the first operation may be included in the sweep loop programmatically because when the user indicates the parameter to be swept on in 1102, the system (e.g., the development environment) can determine the operation to which the parameter belongs or corresponds, and thus can automatically include the operation in the sweep loop. In 1106, second user input specifying a sweep configuration for a sweep on the indicated parameter may be received. In other words, the user may provide input configuring the sweep, e.g., via one or more dialogs, wizard, etc. For example, in one embodiment, specifying the sweep configuration may include specifying one or more of: a range of values for the indicated parameter, a number of iterations for the sweep (i.e., the number of values of the parameter or data points used in the sweep), an interpolation type, a step size for the sweep on the indicated parameter, one or more specific values in the range of values for the parameter; and a source for at least a portion of the sweep configuration, e.g., a file or user input. Note that some of these configuration parameters are redundant, e.g., the step size may be computed from the range and the number of points or values of the parameters (increments), assuming equal increments in the value. FIG. 12B illustrates another (wizard) dialog of the GUI mentioned above, whereby the user may view and set values of configuration parameters specifying the sweep. As FIG. 12B shows, in this example, GUI elements are provided for entry and display of interpolation type (shown set to “exponential”), start and stop values for the parameter indicating the parameter range for the sweep, and a value for the number of points (i.e., the number of values of the parameter) for the parameter sweep. Note that the number of points for the parameter sweep generally corresponds to the number of iterations of the sweep over that parameter, although in nested sweeps involving multiple parameters, described in more detail below, the sweep may include multiple passes through the range of a given parameter, and so the total number of iterations in the sweep may be greater than the number of data values for that parameter. As FIG. 12B also shows, in one embodiment, the user may provide a file name, e.g., a sweep file, which the system may use to access sweep configuration information stored in the file, and thus configure the sweep. In one embodiment, the sweep values may be calculated based on the range provided by the user in 1106. However, in some cases, the user may wish to set or edit one or more of the calculated values “by hand”, i.e., manually. For example, if the sweep is over a parameter on a hardware device, it may be that one or more of the calculated values may not be valid for that device, i.e., may not be allowable values according to the specification of the device. Allowing the user to manually edit a value may obviate having the calculated values be coerced at runtime by the application (i.e., the signal analysis function). Thus, in one embodiment, the GUI may include an “Edit Individual Sweep Values” field whereby the user may indicate that individual parameter values in the parameter range are to be modified manually. FIG. 12C illustrates a dialog for making such modifications. As FIG. 12C shows, in one embodiment, a dialog or panel (or other GUI element) may be provided (e.g., invocable by the user) whereby the user may manually modify specific values in the range of values for the parameter. In the example of FIG. 12C, point or data value number 2 has been selected by the user to modify. In this example, the user may simply type in a new value, and so modify the relevant point or value. In one embodiment, specifying a sweep configuration may include specifying resultant data from the sweep. In other words, the user may specify output or results for the sweep, e.g., data that may be collected or accumulated and saved during the sweep, e.g., for each iteration of the sweep. FIG. 12D illustrates a dialog that displays selectable outputs for the sweep, e.g., outputs corresponding to one or more of the signal operations (function blocks) included in the signal analysis function. As FIG. 12D shows, in this example, a tree diagram is displayed in the dialog, where the tree diagram presents output signals or data (names or icons) corresponding to operations or function blocks (also shown), e.g., “basic function 1” from the Basic Function function block, “filtered data 1” from the Filter function block, and “dc 1” and “rms 1” from the DC-RMS function block. As FIG. 12D also shows, in one embodiment, a field may also be provided whereby the user may enter a name of the specified output(s), e.g., “rms 1 vs. frequency (Hz)”, as shown. In one embodiment, a file browser may be provided to allow the user to browse the computer system for a desired configuration file. FIGS. 13A-13E illustrate embodiments where the sweep functionality is represented by a sweep function block. The sweep function block may be invoked and included in a function block diagram as described above in detail, and illustrated in FIG. 13A. As also described above, the function block (the sweep function block) may have corresponding configuration dialogs (or equivalents) that the user may invoke to display and/or edit parameters associated with the function block. In the embodiment shown in FIG. 13A, a tabbed set of configuration dialogs are shown, where the current active panel is the “Configuration” panel for the sweep function block, including GUI elements for displaying, setting, selecting, and editing sweepable parameters, interpolation type, parameter range, and a configuration file, similar to the wizard dialog of FIG. 12A. FIG. 13B illustrates an embodiment where the user has invoked a popup dialog of sweep options, specifically, sweepable parameters of the Basic Function function block for the sweep from which the user may select the parameter or parameters to be swept. Note that the embodiments of FIGS. 13A and 13B also include a graphical display area where, in this example, the specified sweep points (data values for the parameter to be used in the sweep) may be displayed, either graphically (as shown), or alternatively, in tabular form. In the example of FIG. 13A, the user has selected “frequency (Hz) (Basic Function)” as the parameter to sweep on. The user may then press the “Add” button below the sweepable parameters display, thereby specifying that parameter for the sweep. To specify a sweep over multiple parameters, e.g., in a parallel sweep, the user may select additional parameters to be swept on, e.g., pressing the “Add” button for each selected parameter. As noted above, given the selected parameter (e.g., frequency), the method may automatically determine the corresponding function block (e.g., the Basic Function function block), and add that function block to the sweep loop. The method may then create an output to the sweep function block and associate that output with the parameter being swept. Then, when executing (at runtime), the Basic Function function block knows to use the latest sweep value for that parameter (e.g., frequency) provided by the sweep block, rather than the value for the parameter received from its configuration dialog. Similarly, once the resultant data or output to be collected or accumulated over the sweep has been specified, the method may automatically determine the function block that owns that output (e.g., the DC-RMS function block), determine all the function blocks in the diagram upon which the DC-RMS function block depends (e.g., the Filter function block and the Basic Function function block), and automatically add those function blocks to the sweep loop. The method may then create another output to the sweep function block for the resultant data or output, enabling the user to specify further operations on or otherwise use the resultant data or output. More generally, as described above, in a preferred embodiment, the signal analysis function may include a plurality of operations, where, for example, the first operation may have dependencies on one or more others of the plurality of operations. In one embodiment, one or more other operations of the plurality of operations may be determined for inclusion in the sweep loop, where performing the sweep on the indicated parameter further includes performing the one or more other operations (included in the sweep loop). In one embodiment, determining the one or more other operations of the plurality of operations for inclusion in the sweep loop may include receiving third user input indicating the one or more other operations of the plurality of operations for inclusion in the sweep loop, and programmatically including the one or more other operations in the sweep loop. Similar to the heuristic technique described above regarding the programmatic determination of signal sources for a function block, in one embodiment, determining the one or more other operations of the plurality of operations for inclusion in the sweep loop may include programmatically analyzing dependencies among prior operations and the first operation to determine the one or more other operations, where the first operation has a dependency on at least one of the one or more other operations, and programmatically including the one or more other operations in the sweep loop. FIG. 13C illustrates an embodiment of the GUI of FIG. 13A where the Sweep Loop panel of the configuration GUI is displayed. As FIG. 13C shows, an “Add/Remove” GUI element is provided for manually adding and removing function blocks from the sweep loop. In this example, the Basic Function function block, the Filter function block, and the DC-RMS function block have been added to the sweep loop. FIG. 13D illustrates an embodiment of the GUI of FIG. 13A where the Data Collection panel of the configuration GUI is displayed. As FIG. 13D shows, a GUI element may be provided that facilitates user selection of the output data to be collected during the sweep, here shown as “rms 1”, indicating a root mean square output from the DC-RMS function block. FIG. 13E illustrates yet another embodiment of the GUI, where a popup dialog presents a tree diagram indicating the function blocks in the sweep loop and their respective outputs, similar to the tree diagram of FIG. 12D, where each of the indicated output signals may be selected by the user as outputs for the sweep. Thus, the GUIs of FIGS. 13D and 13E may correspond functionally with that of FIG. 12D, described above. Thus, in one embodiment, the signal analysis operation may include a plurality of operations, including the first operation, where each of the plurality of operations corresponds to a respective function block, and where the corresponding function blocks for the plurality of operations may be displayed in a diagram that visually represents I/O relationships between the function blocks. As noted above, in a preferred embodiment, the configured sweep corresponds to a sweep function block, and the sweep function block is displayed in the diagram substantially indicating which of the corresponding function blocks are included in the sweep. In a preferred embodiment, the method may include graphically indicating in the diagram which of the corresponding function blocks are included in the sweep. For example, note that in the embodiment shown, the sweep function block is placed in the diagram at the beginning of the function blocks included in the sweep loop, and that the diagram also includes a graphical loop indicator drawn around the included function blocks, indicating the function blocks to be included in the sweep. In various embodiments, the user may specify a single parameter sweep, a parallel sweep, and/or a nested sweep, i.e., a sweep within a sweep. A single parameter sweep is simply a sweep over a single parameter, as described above. A parallel sweep, also referred to as a diagonal sweep, refers to a sweep in which multiple parameters are varied in parallel (where the numbers of points for each parameter are preferably equal), i.e., all of the swept parameters are varied in tandem. It should be noted that a parallel sweep may involve multiple parameters from a single function block, single parameters from a plurality of function blocks, or a combination of the two. Similarly, multiple outputs (resultant data) may also be specified, i.e., a plurality of outputs may be collected over the same sweep run. A nested sweep involves multiple sweeps in a hierarchy, where the sweeps may be single parameter sweeps and/or parallel sweeps. Note that in one embodiment, in the case of nested sweeps, multiple sweep blocks may be included in the diagram, e.g., a respective sweep block per sweep. Thus, receiving first user input indicating the parameter for the first operation further may include receiving further first user input indicating one or more additional parameters for the first operation, where the parameter and the one or more additional parameters include a plurality of parameters. Similarly, receiving the second user input specifying a sweep configuration for a sweep on the indicated parameter may further include specifying the sweep configuration for a sweep on the indicated one or more additional parameters. In one embodiment, the user may enter additional first user input specifying additional operations to be included in the sweep, e.g., in an iterative manner, where one or more parameters for each additional operation are specified as described above, and where a sweep configuration is further specified regarding the parameters. In one embodiment, information specifying the plurality of operations included in the signal analysis function may be stored, where the information specifying the plurality of operations is executable in the signal analysis function development environment to perform the signal analysis function. For example, the information may include a script or equivalent that may be executed in the development environment. In another embodiment, a graphical program implementing the signal analysis function may be programmatically generated based on the stored information, where the graphical program is executable to perform the signal analysis function, i.e. independent of the development environment, as described in detail above. In 1108, the sweep may be performed on the indicated parameter in accordance with the sweep configuration, thereby generating resultant data for the sweep. The resultant data from the sweep may be any type of data that relates to the signals being generated, acquired, and/or analyzed, examples of which are described above. For example, in various embodiments, the resultant data may include signal data in the form of a signal plot, tabular data, and so forth. In one embodiment, where the GUI includes a sweep configuration dialog corresponding to the sweep configuration, and where the configuration dialog includes one or more GUI elements indicating the sweep configuration, the method may also include receiving third user input to the configuration dialog modifying the sweep configuration, thereby generating a modified sweep configuration. In other words, once the above sweep configuration has been performed, the user may be presented with a panel, dialog, etc., that includes one or more GUI elements displaying the sweep configuration, and which may operate to receive further user input modifying the configuration. Performing the sweep on the indicated parameter in accordance with the sweep configuration may then include performing the sweep on the indicated parameter in accordance with the modified sweep configuration. In one embodiment, the sweep configuration dialog (or equivalent) may be invoked or displayed during run-time, i.e., while the sweep is being performed. In other words, in one embodiment, the sweep configuration may be modified during the sweep, i.e., dynamically, such that the remainder of the sweep is performed in accordance with the modified sweep configuration. As described above, in some embodiments, the user may further configure the sweep to be performed on one or more additional parameters, e.g., in parallel and/or nested sweeps, and so performing the sweep on the indicated parameter in accordance with the sweep configuration may further include performing the sweep on the indicated one or more additional parameters. For example, the sweep configuration may specify a parallel sweep of at least a first subset of the plurality of parameters, and/or a nested sweep of at least a second subset of the plurality of parameters. Finally, in 1110, the resultant data for the sweep may be stored, and as FIG. 11A indicates, may optionally be displayed on a display, e.g., in a display of the GUI. In one embodiment, the resultant data may be stored on the host computer system 82 and/or transmitted to another device coupled to the host system. Example output for a sweep is provided in FIGS. 13F-13H, described below. Thus, in various embodiments, a Graphical User Interface (GUI) may be displayed on the display, where receiving the first input and receiving the second input may include receiving the first and second inputs to the GUI. As described above, in one embodiment, the GUI includes a wizard, e.g., a sweep wizard, where displaying the GUI may include displaying a sequence of dialogs to interactively guide the user in specifying the sweep. As also described above, in one embodiment, the GUI may include one or more configuration dialogs corresponding to the first operation, whereby the user may specify the sweep. In a preferred embodiment, the GUI may be included in a signal analysis function development environment, such as described herein. Thus, the method may include displaying the GUI on the display, receiving the first and second inputs to the GUI, and displaying the resultant data for the sweep in the GUI. FIG. 11B is a more detailed flowchart diagram of one embodiment of the method of FIG. 11A. More specifically, FIG. 11B flowcharts one embodiment of step 1108 of the method of FIG. 11A, where the sweep is performed on the indicated parameter in accordance with the sweep configuration. As FIG. 11B shows, in 1112, a next sweep value of the parameter may be provided to the first operation as a current value of the parameter for the first operation. In various embodiments, the next sweep value may be retrieved from a file, computed in real-time, and/or received from another system or process, e.g., a system of process coupled to or comprised in the host computer system 82. In 1114, the first operation may be performed using the current sweep value of the parameter, thereby generating corresponding resultant data, and the corresponding resultant data stored, as indicated in 1116. In one embodiment, the corresponding resultant data may also be displayed in the GUI, e.g., in a graph or table, e.g., as the data are generated. The above steps may then be repeated in accordance with the sweep configuration. In other words, the providing a next sweep value, the performing the first operation using the current sweep value of the parameter, and the storing the corresponding resultant data may be performed in an iterative manner in accordance with the sweep configuration, as indicated in 1118, where after each iteration, the method may determine whether there are further iterations to perform, i.e., whether there are further sweep values of the parameter that have not been used, and if so, the method may continue with step 1112, and proceed as described above until there are no further sweep values to process, i.e., until a stopping condition specified in the sweep configuration obtains, in which case the method may terminate, as indicated in 1120. In one embodiment, performing the sweep on the indicated parameter in accordance with the sweep configuration may include batch computing each of the sweep values in accordance with the sweep configuration prior to the repeating. In other words, before the iterative process begins, all of the sweep values may be computed. Then, at the beginning of each iteration, the next (successive) value may be provided to the first operation. Alternatively, in another embodiment, providing the next sweep value of the parameter to the first operation as a current value of the parameter for the first operation (step 1112 above) may include computing the next sweep value in accordance with the sweep configuration. In other words, each sweep value may be calculated as needed in the iterative process, i.e., “on the fly”. Thus, performing the sweep on the indicated parameter in accordance with the sweep configuration may include iteratively performing the first operation, where at each iteration the first operation is performed using a respective value of the parameter, and where at each iteration corresponding resultant data are generated. In one embodiment, performing the first operation may include performing the first operation using a hardware device, where iteratively performing the first operation may include triggering the hardware device at each iteration. For example, an arbitrary waveform generator (hardware device) may be triggered each iteration to provide a stimulus signal to a filter, where the parameters determining the filtering attributes are varied for each iteration, and a corresponding output waveform generated (for each iteration). The output waveforms may all be plotted on a graph, e.g., overlaid on a 2D plot, or presented in a 3D graph, where the succession of waveforms generated by the sweep form a surface. In one embodiment, the resultant data for each iteration of the sweep may be displayed in real-time, i.e., as it is generated, such that an animated display of results is presented to the user as the sweep executes. FIGS. 13F-13H illustrate example output from a sweep operation. As FIGS. 13F-13H show, a signal analysis function, represented by function blocks (as described above), includes a specified sweep operation that includes the Basic Function, a Filter, and a DC-RMS operation. FIG. 13F illustrates preliminary results of the sweep, labeled “collected data”, FIG. 13G illustrates intermediate results of the sweep, and FIG. 13H illustrates the complete collected data from the sweep. Note that in each of these illustrates, the (tabbed) display window is a “Data Viewer” window, as opposed to the “Step Setup” window/panels described earlier during the specification of the sweep. Thus, various embodiments of the systems and methods described herein may facilitate rapid (and relatively easy) specification and performance of sweeps in a signal analysis function, where the sweep may be over single parameter and/or multiple parameters, and where the sweep may be a parallel sweep, a nested sweep, or a combination of both. FIGS. 14-15F—Automatic Signal Display In one embodiment, the graphical display of the GUI of the signal analysis function development environment may include additional functionality. For example, many applications may use or manipulate multiple types of data, e.g., time-domain waveforms, frequency-domain waveforms, digital-domain waveforms, xy-pairs, and scalars, among others, and there may be different ways of viewing these different data types, e.g., different display tools. For example, a time-domain waveform typically cannot be viewed on the same graph as a frequency-domain waveform. Note that as used herein, the term “display tool” may refer to any type of graphical display tool, i.e., graph, table, chart, and so forth. Note also that as used herein, the data displayed in such display tools may be referred to as “signals” or “signal data”. Whatever the data type or the display tool, it would be desirable for a user to have the capability to view and interact with different types of data without having to manually distinguish one data type from another. Thus, in one embodiment, various display tools may be provided for displaying a plurality of data types to the user, e.g., via graphs, tables or other formats, as needed. Thus, in one embodiment, display tools, e.g., graphs and tables, such as included in some embodiments of the signal analysis function development environment described herein, may automatically distinguish between different data types and may present the data in a manner commensurate with the data's type. For example, when display of a signal is requested, e.g., by the application or by the user, the burden of choice among display types may be removed from the user and the appropriate display tool created or selected automatically by the application to view the signal. In one embodiment, exceptions to this automatic functionality may be handled manually, e.g., by the user. FIG. 14 is a flowchart of one embodiment of a method for automatically displaying signal data based on signal type. Various embodiments of these display tools, also referred to as “automatic display tools”, “smart display tools”, or “smart graphs”, are described below with reference to FIGS. 15A-15F. Note that although the embodiments described below are presented in the context of the signal analysis function development environment described above, the display tool techniques described herein are broadly applicable to data display in other application domains and tools. For brevity, the term “application” is used below to refer to the software environment in which the method is performed. In one embodiment, the method may proceed as described below. Note that in various embodiments, some of the steps shown may be performed concurrently, in a different order than shown, or may be omitted. Additional steps may also be performed as desired. As FIG. 14 shows, in 1402, a default display tool may be displayed, where the default display tool may be operable to display signal data of a default data type. In one embodiment, the default display tool may comprise a graph for displaying signal plots, or, alternatively, may comprise a (blank) table for displaying tabular data. In one embodiment, the default display tool may be displayed in response to user input, e.g., invoking generic data display functionality in the application. In a preferred embodiment, the application may launch with the default display tool visible. FIG. 15A illustrates an example GUI display from the signal analysis function development environment described above, where a specified signal analysis function is represented by a set of function blocks, as also described above. In this example, two basic function waveforms are provided by respective Basic Function function blocks, and power spectra for the waveforms generated by respective Power Spectrum function blocks, as shown. A default display tool is also shown in the GUI of FIG. 15A. For example, as FIG. 15A shows, in one embodiment, the default display tool may take up substantially the entire viewing area of the GUI. In this example, the default display tool is a time-domain graph for displaying time-domain signal plots. In 1404, first user input may be received requesting display of a first signal. The user input may be received in a variety of ways. For example, in a preferred embodiment, the user may “drag and drop” a signal icon corresponding to the first signal onto the default graph, as described earlier. In another embodiment, the user may right-click on the signal icon to invoke various options related to the signal, and may select a “display” option or equivalent. In yet another embodiment, the user may right-click on the default graph to invoke a list or menu of signals from which the first signal may be selected. Other means of requesting display of the first signal are also contemplated. In 1406, the first signal may be programmatically analyzed in response to the first user input. In a preferred embodiment, the first signal may be programmatically analyzed to determine a data type of the first signal. Note that as used herein, the term “data type” may refer to broad signal types, such as time-domain data (values vs. time), frequency domain data (values vs. frequency), and spatial-domain data (x vs. y), and may also refer to programming data types, such as, for example, integer, floating point, and Boolean data, including arrays or vectors of such data, among others. In one embodiment, user-defined data types may also be accommodated. For example, the user may define various “custom” data types, and may also specify or provide respective display tools for displaying data of these user-defined types. In 1408, a display tool operable to display the first signal may be programmatically determined based on the analysis performed in 1406. In a preferred embodiment, the display tool may be determined based on the data type of the first signal. For example, in one embodiment, programmatically determining the display tool based on the determined data type may include performing a table look-up based on the determined data type to determine the display tool. In other words, the method may use the determined data type for the first signal to lookup a suitable display tool, i.e., a display tool suitable for displaying signal data of the determined data type. The first signal may then be displayed in the display tool. Depending upon the data type of the first signal, and the type of the default display tool, the display of the first signal may be performed in different ways. For example, as FIG. 14 shows, in 1409, a determination may be made as to whether the determined display tool of 1408 is the default display tool (of 1402 above), i.e., whether the default display tool is operable to display the first signal. Said another way, a determination may be made as to whether the determined data type is compatible with the default data type (of 1402 above), and if the determined data type is compatible with the default data type, the default display tool may be determined to be the display tool, and so in 1410, the first signal may be displayed in the default display tool. FIG. 15B illustrates the GUI of FIG. 15A, where, following the example of FIG. 15A, the user has requested display of a time-domain signal, e.g., by dragging and dropping a signal icon onto the default display tool of FIG. 15A, and where the signal is displayed in response. Since the data type of the signal is supported by the default display tool, the signal is displayed by the default display tool, i.e., the default graph is of the correct type for displaying the signal. If the determined display tool of 1408 is not the default display tool, then in 1412, the default display tool may be replaced with the determined display tool, and the first signal displayed in the determined display tool, as indicated in 1414. In other words, if the determined data type is not compatible with the default data type, a replacement display tool operable to display signals of the determined data type may be determined, the default display tool replaced with the determined (replacement) display tool, and the first signal displayed in the determined (replacement) display tool. In one embodiment, determining the replacement display tool may include creating the replacement display tool. In other words, the type of display tool may be determined based on the analysis of 1406 (e.g., by table lookup), and the display tool programmatically created, e.g., based on a pre-defined specification for that display tool type. FIG. 15C illustrates the GUI of FIG. 15A, but where the user has requested display of a frequency-domain signal, e.g., by placing a frequency-domain signal icon on the default display tool. As described above, the application may automatically replace the default time-domain graph with a frequency-domain graph, thus providing the correct display tool for the signal of the frequency-domain type without consuming additional screen display space, as only one display tool, i.e., graph, is still presented. As noted above, in a preferred embodiment, the first signal comprises signal data. Thus, depending upon the type of the signal data, the determined display tool may vary. For example, in an embodiment where the signal data comprise signal plot data, the display tool preferably includes a graph. Note that depending upon the data, the graph may be a 2D graph, a 3D graph, or any other type of graph suitable for displaying the data. In an embodiment where the signal data comprise tabular data, the display tool preferably comprises a table. In cases where the signal data comprises neither plot data or tabular data, the determined display tool may include an indicator operable to display the signal data. For example, if the signal data is a Boolean, a simple Boolean indicator, such as an “LED” type indicator, may be used to present the data (or datum). In cases where the data type of the signal is a user-defined type, user-defined or user-specified display tools may be provided and used as needed. As noted above, in a preferred embodiment, the method of FIG. 14 is performed in the context of a GUI, e.g., in the signal analysis function development environment described above. For example, the method preferably includes displaying a Graphical User Interface (GUI), where receiving the first user input includes receiving the first user input to the GUI, and where displaying the first signal in the display tool includes displaying the first signal in the GUI. In other words, the display tool is displayed in the GUI. In some cases, when the user requests display of the signal, there may already be a display tool displayed in the GUI, where the display tool displays one or more prior signals. For example, the method may include displaying a first display tool prior to receiving the first user input (of 1402), where the first display tool displays a prior signal of a first data type. In one embodiment, programmatically determining the display tool may include: if the determined data type is compatible with the first data type, determining that the first display tool comprises the display tool, and if the determined data type is not compatible with the default data type, determining a second display tool operable to display signals of the determined data type. Thus, displaying the first signal in the display tool may include: if the determined data type is compatible with the first data type, displaying the first signal in the first display tool with the prior signal, and if the determined data type is not compatible with the first data type, displaying the second display tool, and displaying the first signal in the second display tool. As indicated above, in one embodiment, receiving the first user input requesting display of the first signal may include the user dragging and dropping a signal icon corresponding to the first signal onto the first display tool. As also indicated above, in one embodiment, determining the second display tool may include creating the second display tool. The above situation may be extended to multiple prior signal displays, where for example, in one embodiment, a plurality of display tools may be displayed prior to receiving the first user input, where the plurality of display tools correspond respectively to a plurality of data types, and where each display tool displays one or more respective signals of a respective data type of the plurality of data types. Programmatically determining the display tool may thus include programmatically determining if the plurality of display tools comprises a matching display tool operable to display signals of a data type compatible with the determined data type, and if the plurality of display tools comprises a matching display tool, determining that the matching display tool comprises the display tool, and if the plurality of display tools does not include a matching display tool, determining a second display tool operable to display signals of the determined data type, wherein the second display tool comprises the display tool. Similarly, displaying the first signal in the display tool may include: if the plurality of display tools comprises a matching display tool,displaying the first signal in the matching display tool, and if the plurality of display tools does not comprise a matching display tool, displaying the second display tool, and displaying the first signal in the second display tool. Thus, in one embodiment, the method described above with reference to FIG. 14 may be performed iteratively, where additional or successive signals may be respectively displayed on prior display tools if they support the data types of the signals, or, in cases where the data types of the signals are not supported by the prior display tools, further display tools determined (and optionally created) for display of the signals. FIG. 15D illustrates an example of the GUI of FIG. 15A, where the default display tool is already displaying prior signals, e.g., basic function 1 and basic function 2, when a request is made to display a third signal, in this case, a power spectrum. Note that the two prior signals are time-domain signals, while the new signal is a frequency-domain signal, and so a new display tool is programmatically determined (and optionally created). As shown, the new display tool is operable to display frequency-domain signals, and so is the appropriate display tool for the new signal. Since a new display tool is not automatically determined (or optionally created) unless a type conflict is generated by a user requesting display of a signal on an incompatible display tool, a manual way of adding a display tool within the application may be provided. In one embodiment, the user may manually request a display tool. For example, in one embodiment, once the first signal is displayed (in 1410 or 1414), second user input requesting display of a new display tool may be received. A default display tool may be displayed in response to the second user input, where the default display tool is operable to display signal data of a default data type, as described above. Third user input requesting display of a second signal may then be received, e.g., by dragging and dropping a signal icon onto the default display tool. The second signal may be programmatically analyzed in response to the third user input to determine a data type of the second signal, and if the determined data type of the second signal is compatible with the default data type, the second signal may be displayed in the default display tool (as described above). If, on the other hand, the determined data type is not compatible with the default data type, the default display tool may be replaced with a replacement display tool operable to display the second signal (as also described above) and the second signal displayed in the replacement display tool. Thus, in the event that the default display tool (or any prior display tool) is already displaying signals of a different type than currently requested, no replacement may take place, but an additional display tool may be displayed (and optionally created) of the appropriate type, and the requested signal displayed therein. Said another way, upon requesting a new display tool, a new instance of the default display tool may be determined and provided (and optionally created). If the user requests display of an incompatible signal, e.g., places an incompatible data type on the new unused default display tool instance, the application may automatically replace it with the appropriate display tool instance. It is important to note that multiple signals may be viewed on the same graph, as long as the types of the signals are compatible. FIG. 15E illustrates an example of the GUI of FIG. 15A, where the default display tool is already displaying prior signals, e.g., basic function 1 and basic function 2, and where a request is made to display a new display tool (e.g., a manual request). As described above, the default display tool (a time-domain graph) is then displayed (in addition to the prior display tool), and the user may subsequently request display of additional signals using the newly displayed display tool. Note that if the user requests display of a signal that is not compatible with the newly displayed default display tool, the display tool may be automatically replaced with an appropriate display tool, as described above, and as illustrated in FIG. 15F, where a power spectrum signal, labeled “magnitude 2” is displayed in the replacement display tool (a frequency-domain graph). Thus, various embodiments of the system and method described above may facilitate automatic presentation of signal data in an appropriate display tool, e.g., a graph, table, indicator, or other type of display tool, based on the signal data, e.g., based on the data type of the signal. FIGS. 16A-17G—Soft Front Panel In one embodiment, the GUI may include a soft front panel (SFP), where the soft front panel provides or includes an interface for a respective hardware device, e.g., a hardware board, and where the soft front panel emulates a front panel for the device. For example, if the device or board is a Digital Multi-Meter (DMM), the soft front panel preferably emulates the front panel (i.e., a physical front panel) of the DMM. In one embodiment, a soft front panel may be provided for each of a plurality of interactive virtual instrument (IVI) classes, e.g., for DAQ boards, DMMs, oscilloscopes, etc. Thus, the GUI may present an interface to the user that substantially replicates the functionality and appearance of a hardware front panel, where the user may select or invoke various operations, e.g., signal analysis operations, via controls presented on the soft front panel, where information specifying the selected or invoked operations may be stored, as described above. FIGS. 16A-17G illustrate various aspects of one embodiment of the signal analysis system where soft front panels are included in the GUI. More specifically, FIGS. 16A and 16B illustrate an architecture and process flow for the system, according to one embodiment, and FIGS. 17A-17G are screenshots illustrating soft front panels, according to one embodiment. Architecture FIG. 16A is a block diagram of a virtual interactive instrument (VII) architecture and its components, according to one embodiment. As FIG. 16A shows, in one embodiment, the architecture may include a core component DLL (Dynamic Linked Library) that may export methods and attributes, e.g., for access and use by other systems, although other implementations are also contemplated, the DLL being but one exemplary implementation. Example exported methods are described below. Note that the embodiment shown utilizes portions of the LabVIEW graphical programming system, although other systems and approaches are also contemplated. The core component DLL may include or access a virtual interactive instrument (VII) SFP, examples of which are described below with reference to FIGS. 17A-17G. The VII SFP may couple to a dynamic data store, and may be dynamically executable via a virtual interactive instrument execution layer, as shown, where the virtual interactive instrument execution layer may include or couple to various functional components such as limits, maths (analysis), LabVIEW plugins, a switch executive, and a session manager, among others, which may operate to provide respective functionality for the interface. As FIG. 16A also shows, in one embodiment, the VII execution layer may also couple to (and communicate with) various drivers, e.g., with a driver layer. More specifically, in the example shown, the VII execution layer may couple to or access an IVI class driver that may provide basic or generic IVI interface functionality, as well as an IVI compliant instrument driver, i.e., an instrument specific driver that may provide instrument specific functionality or capabilities, such driver functionality being well known in the art. As shown, the two IVI drivers may also couple to or communicate with an IVI engine, which may itself couple to a data store. In the embodiment shown, the driver software may couple to or communicate with instrumentation hardware, such driver functionality being well known in the art. For example, a driver for a soft scope may communicate with a scope hardware board coupled to or included in the host computer system 82 to control or operate the scope. Thus, in one embodiment, at the core of each virtual interactive instrument, a dynamic link library may encapsulate the functionality of the target IVI instrument class, where additional modular software components, e.g., layered over the DLL software, may provide common generic functionality. In one embodiment, the DLL may be accessed and utilized by various different related systems and products. For example, in one embodiment, the VII DLL may be called from an executable through an exported “VIIADisplaySPF” method (or equivalent), which may in turn display the SFP to the user. The user may then interact via the SFP to drive the corresponding instrument. In another embodiment, the VII DLL may be encapsulated or wrapped in a graphical program node, such as an Express VI block, as provided in the LabVIEW graphical program development environment, where functionality of the DLL may be invoked or executed via the node, e.g., by including and executing the node in a graphical program. For further information regarding Express blocks, please see U.S. patent application Ser. No. 09/886,496, titled “System and Method for Programmatically Creating Graphical Program Code in a Graphical Program” , filed Jun. 20, 2001, which was incorporated by reference above. In yet another embodiment, the VII DLL may be invoked from (or included in) another tool, such as, for example, National Instruments' TestStand product, where the VII DLL may be implemented within a Step Type. In this example, under step edit conditions, the SFP may be displayed for interactive instrument configuration. Then, when the step executes under a TestStand execution, a “VIIAExecution” method (or equivalent) may be called, passing in previously defined data contained within the step from the instrument's SFP. Note that these are but exemplary embodiments, and are not intended to limit the implementation, invocation, or use of the VII DLL (or equivalent) to any particular system or approach. Exported Methods In one embodiment, the VII DLL may export various methods for use by external systems or processes. For example, in one embodiment, the VII DLL may export a “DisplaySFP” method and an “Execution” method, e.g., “VIIA-<class instrument name>-DisplaySFP” and “VIIA-<class instrument name>-Execution”, where the <class instrument name> refers to the name of the particular virtual interactive instrument being used. Note that “VIIA” refers to Virtual Interactive Instrument Architecture. For example, the DisplaySFP method may be called by an external application, where the method may display the SFP for the relevant instrument class, and set the SFP controls/labels to values contained within the method's parameter list. The user may then interactively configure the instrument and execute the settings, e.g., by clicking on a “RUN” command (or equivalent), which may in turn call the Execution method, passing in any required information. In one embodiment, the parameter list for the method may include software pointers to structures for each functional component of the VII architecture. In one embodiment, the pointers/structures may be defined or designated as specific data types, e.g., via a typedef mechanism, as is well known in the art of programming. In one embodiment, the typedef may be a “strict typedef”, where not only the data type of generated structures of the respective “strict” data type are the same, but all aspects of the structures are the same, e.g., appearance, etc. Such a parameter list may facilitate passing configuration settings from the SFP to the calling application. Examples of parameter structure headings may include, for example, IVI attributes to support configuration of the corresponding instrument, switch executive attributes, maths (analysis) attributes, and limits/masks attributes, among others. In one embodiment, the Execution method may be called by an external application. Internally, the method may interrogate data contained within the structures in the parameter list and execute methods of internal components in a predefined manner. FIG. 16B illustrates basic execution flow of internal components within the VII architecture, according to one embodiment. FIGS. 17A-17G illustrate various embodiments of a soft front panel. In a preferred embodiment, a virtual interactive instrument soft (or software) front panel may be created for each of a plurality of IVI instrument classes. In one embodiment, the SFP may expose the base and extension methods/attributes of the instrument class to the user via an easy to use GUI, i.e., the SFP. Additional functionality may be exposed from the underlying components of the VII architecture to facilitate advanced analysis functionality, e.g., “Maths” (analysis) and Limit/Mask checking capability, for example, using LabVIEW VI polymorphic/plug-in technologies. It should be noted that the example SFPs described below are intended to be exemplary only, and are not intended to limit the SFPs to any particular appearance or functionality. FIG. 17A illustrates an example of a Virtual Interactive DMM SFP, according to one embodiment. As FIG. 17A shows, the SFP comprises a GUI with a variety of displays, indicators, and controls, for interactive operation of the DMM. In this example, the top left section of the GUI comprises a primary display that may operate to display outputs and/or settings for DMM operations, including, for example, Offset, Max, Min, Range, Resolution, AutoRange, measurement limits, and test results (e.g., PASS/FAIL), among others. Also included in this example SFP is a display area for DMM information, e.g., for display of any type of information, e.g., auxiliary data, which may be useful to the user to operate or monitor the DMM. Below the primary display of the SFP is shown a plurality of tabbed configuration panels for configuration and display of various parameters of or for the DMM, where in this example, the configuration panels include a base class panel labeled “DMM”, an Extensions panel, an Extra Settings panel, a Maths or Analysis panel, and a Limit panel. Directly above these panels are ring controls for selecting a device (labeled “Device”) and for setting data resolution (labeled “Resolution”). To the right of the tabbed configuration panels is a tabbed set of operational panels, including a DMM Execution panel with RUN, Abort, and Sw Trigger buttons, and a Switching panel (described below with reference to FIG. 17G). As shown, the bottom right of the SFP includes Save and Quit buttons for saving the configuration and exiting the process, respectively. In this example, the IVI base class configuration panel may allow the user to select the measurement resolution, function, range and the IVI compliant DMM from the Device ring control and click the “RUN” Button contained with the DMM Execution panel, thereby instigating the configured operation (e.g., measurement) utilizing the underling Virtual Interactive Instrument Execution method, described above. The returned (measurement) data may then be displayed within the digital display of the SFP. FIG. 17B illustrates the SFP of FIG. 17A, but with the Extensions configuration panel selected and displayed. As FIG. 17B shows, the Extensions panel may include sections for configuring Measurement, Triggering, and Miscellaneous parameters. For example, the Measurement section provides selectable options for measurements such as (but not limited to) AC Measurement, Frequency Measurement, and Temperature Measurement, where the Temperature Measurement further includes options specifying Thermocouple, RTD (Resistive Thermal Device), and Thermistor, although it should be noted that other types of measurement are also contemplated. In the embodiment shown, the Triggering section includes options for Multi-Point triggering and for Trigger slope. As shown, the Miscellaneous section includes options for Device Information, Auto Zero, and Power Frequency. FIG. 17C illustrates the SFP of FIG. 17A, but with the Extra Settings configuration panel selected and displayed. As FIG. 17C shows, the Extra Settings panel may include sections for configuring Multipoint and AC Measurement parameters. For example, the Multipoint section provides fields for Multipoint options such as (but not limited to) Sample Count, Sample Interval (mS), Trigger Count, Sample Trigger, and Trigger Source. The AC Measurement section includes fields for Min and Max AC Frequency. FIG. 17D illustrates the SFP of FIG. 17A, but with the Maths or Analysis configuration panel selected and displayed. As FIG. 17D shows, in this embodiment, the Maths panel may include a plurality of user selectable (and user definable) controls, each of which may be associated with a predefined function, e.g., a user defined graphical program, and which may be selected by the user to invoke the respective function, e.g., for inclusion in a signal analysis function (or any other type of function). In other words, each of the plurality of controls may be configured to allow user invocation of custom or predefined functionality in the context of the SFP, e.g., providing “plug-in” functionality. In one embodiment, this type of user-customization may provide access by the user to any functionality desired, e.g., to functionality provided or supported by the LabVIEW graphical programming system. For example, in one embodiment, each “free button” may be associated with an analysis algorithm, e.g., developed within LabVIEW using a pre-defined template. Further description of this feature is provided below. FIG. 17E illustrates the SFP of FIG. 17A, but with the Limits configuration panel selected and displayed. As FIG. 17E shows, in this embodiment, the Limits panel may include controls for Comparison Type, upper and lower bounds for the measurements, and units. A Numeric Format button is also shown, whereby the user may invoke a configuration panel or control to specify a display format for numeric data. FIG. 17F illustrates the SFP of FIG. 17A, but with the Mask configuration panel selected and displayed. As FIG. 17F shows, in one embodiment, the Mask panel may include a control for specifying a Mask Fit, and may also include sections for specifying Upper and Lower Limits for the mask, e.g., options for Upper Constant, Upper Inclusive, and Upper Mask. Each of these sections may also include controls for loading and defining these limits. As FIG. 17F also shows, in this example, the primary display may be operable to display a signal with the specified mask overlaid on the signal plot, allowing the user to easily see how the mask test passes or fails. Note that in this example, a square wave signal has failed the test, and so the displayed test status indicates “FAILED”. In one embodiment, the mask and/or the signal may be modified in response to the test results, where the displayed results may be updated automatically to reflect the relationship between the signal and the mask after the modification. FIG. 17G illustrates the SFP of FIG. 17A, but with the Switching panel displayed, as shown in the bottom right of the SFP. As shown, the Switching panel may include fields for specifying (and displaying) a Switch Executive Project and a Switch Group/Root, and a SET button for setting the specified values of these parameters. Thus, in one embodiment, the GUI for the signal analysis function development environment may include one or more SFPs for user interaction with corresponding instruments or devices. For example, in an alternative embodiment of the method of FIG. 5, receiving user input specifying an operation may include receiving user input indicating a pre-defined graphical program, where the pre-defined graphical program implements the first operation. In a preferred embodiment, the pre-defined graphical program may be associated with a control in the GUI, where the first operation is invocable via user input to the control. The associating may be performed in response to user input indicating an association between the pre-defined graphical program and the control. In one embodiment, the pre-defined graphical program may be displayed in the GUI. For example, the GUI may include a display area for displaying the block diagram of the graphical program. In one embodiment, one or more of the operations of the signal analysis function may be associated with a respective control in the GUI, where the one or more operations are invocable via user input to the respective control. In other words, one or more signal operations may be grouped together, associated with a GUI control, and then invoked (as a group) via user selection or activation of the GUI control. Thus, in one embodiment, receiving user input specifying an operation may include receiving user input to the respective control for the operation, thereby invoking the one or more operations. In one embodiment, an interface may be implemented for an instrument, e.g., for signal analysis in the following manner: A soft front panel may be displayed, where, as noted above, the soft front panel comprises an interface for a respective hardware device, e.g., a hardware board, where the soft front panel emulates a front panel for the hardware device, and where the soft front panel comprises a first plurality of controls for invoking respective signal operations, and where the first plurality of controls substantially corresponds to a respective plurality of physical controls for the hardware device. User input to one of the first plurality of controls may be received specifying an operation, where the operation implements at least a portion of a signal analysis function. Information specifying the operation may be stored, and the operation performed utilizing the instrument, thereby generating resultant data. In one embodiment, the resultant data may then be displayed in the soft front panel. In one embodiment, displaying the soft front panel may include displaying a Graphical User Interface (GUI), wherein the GUI includes the soft front panel. The GUI may also include a second plurality of controls, where each of the second plurality of controls is operable to be associated with a respective one or more operations, and where the respective one or more operations are invocable via the associated one of the second plurality of controls. In one embodiment, user input indicating a pre-defined graphical program may be received, wherein the pre-defined graphical program implements a first operation. The pre-defined graphical program may be associated with a first control of the second plurality of controls in the GUI, wherein the first operation is invocable via user input to the first control. In a preferred embodiment, said associating is performed in response to user input indicating an association between the pre-defined graphical program and the first control. In one embodiment, the pre-defined graphical program may be displayed in the GUI. In another embodiment, the one or more operations of the signal analysis function may be associated with a first respective control of the second plurality of controls, where the one or more operations are invocable via user input to the first respective control. Thus, various embodiments of the system and method may provide an interface for one or more instruments where the interface substantially replicates the front panel of a hardware instrument. Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. | <SOH> FIELD OF THE INVENTION <EOH>The present invention relates to the field of signal analysis, and more particularly to a system and method for interactively specifying and performing signal analysis functions. | <SOH> SUMMARY OF THE INVENTION <EOH>A plurality of function blocks are described for use in specifying and performing a signal analysis function utilizing a plurality of instruments, and a method presented for automatically configuring function blocks selected for inclusion in a plurality of functions blocks specifying or representing a signal analysis function. In one embodiment, each function block may include: a function block icon operable to be displayed in a graphical user interface (GUI) of a signal analysis function development environment, where the function block icon visually indicates a respective signal operation, and a set of program instructions associated with the function icon, where the set of program instructions are executable to perform the respective signal operation, possibly in conjunction with associated hardware. In a preferred embodiment, each function block is selectable from the plurality of function blocks by a user for inclusion in a set of function blocks, wherein each function block operates to perform the respective signal operation continuously upon being selected. Each function block may be operable to provide a respective output based on the respective signal operation, where the respective output is operable to be displayed in the GUI, provided as input to one or more other ones of the set of function blocks, and/or exported to an external device. The set of function blocks may be executable to perform the signal analysis function under the signal analysis function development environment using one or more of the plurality of instruments. Signal operations may be organized by function categories, such as (but not limited to): Create, I/O, Conditioning, Measurement, Processing, File, Test, and Conversion, among others. Thus, in one embodiment, a plurality of function blocks may be used in specifying and performing a signal analysis function utilizing a plurality of instruments. In a preferred embodiment, the plurality of instruments includes two or more virtual instruments (VIs), at least a portion of which may include respective hardware components. In one embodiment, each function block may be selectable from the plurality of function blocks by a user for inclusion in a set of function blocks, where each function block operates to perform the respective signal operation continuously upon being selected. For example, the user may select a first function block from a palette, menu, etc., in response to which the respective signal operation may be performed, preferably executing in a continuous manner until, for example, a stopping condition occurs or the user pauses or terminates the process. The user may then select one or more additional function blocks, which may similarly begin continuous respective operations in conjunction with the first function block. In one embodiment, each function block may be operable to provide a respective output based on the respective signal operation, where the respective output is operable to be displayed in the GUI, provided as input to one or more other ones of the set of function blocks, and/or exported to an external device. In other words, each function block may generate a respective output that may be used as input to or by other function blocks in the set of function blocks, transmitted to an external device coupled to the host computer, and/or displayed in a display tool, i.e., a graph or table, in the GUI. Additionally, one or more of the function blocks may be operable to receive a respective input based on the respective signal operation, where the function block is operable to perform the respective signal operation on the input, e.g., on a signal and/or data, and provide the results as output. In one embodiment, each function block may include an input and an output, where the input is operable to receive signals from one or more of: an external signal source, a file, and/or another function block, and where the output is operable to send resultant signals to one or more of: a display of the GUI, an external device, a file, and/or another, different, function block. Once the user has selected the set of function blocks, the set of function blocks may be executable to perform the signal analysis function under the signal analysis function development environment using one or more of the plurality of instruments. For example, in an embodiment where each function block executes substantially continuously upon selection by the user, when the user is done selecting the function blocks, the signal analysis function (specified and implemented by the set of function blocks) is already being performed. As another example, the user may stop the current execution of the signal analysis function (which was, for example, initiated in steps via the function block selection process), then re-initiate performance of the signal analysis function, thereby invoking execution of the set of function blocks. In another embodiment, information specifying the respective signal operations of the set of function blocks may be saved, e.g., as a script, that may be executed as desired under the signal analysis fuiction development environment. In one embodiment, the set of function blocks may be displayed in a diagram, e.g., in a specified display area of the GUI. The diagram may include one or more of: a linear sequence, a data flow diagram, a tree diagram, and a dependency diagram, among other types of diagram. The diagram may substantially visually represent I/O relationships between the function blocks. For example, where output from a first fimction block is provided as input to a second function block, this relationship may be graphically represented in the diagram, e.g., via a data flow line from the first function block to the second function block, via I/O signal icons displayed in, on, or proximate to each function block icon, and/or by the relative positions of the function blocks, and so forth. In one embodiment, when the I/O relationships between the function blocks change, the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. Thus, if a user changes an I/O relationship between function blocks, the diagram may be updated automatically to reflect the change. Thus, the diagram may comprise or visually represent a script (or equivalent) that is executable to perform the specified signal analysis function under the development environment. Said another way, the diagram may include information specifying the respective signal operations of the set of function blocks, where the information is executable to perform the signal analysis function under the signal analysis function development environment. In one embodiment of the present invention, input and/or output sources for a selected function block (signal operation) may be automatically selected by the system, e.g., based on heuristics or other rules. In other words, in embodiments where each signal operation is comprised in or associated with a respective function block, when a first fimction block is selected by the user that requires an input signal of a certain type, the system may attempt to programmatically determine a prior selected fimction block that provides as output a signal of that type, and may automatically assign that signal/function block as the input for the first function block. One embodiment of a method for programmatic (automatic) configuration of a function block may operate as follows: User input specifying a first operation may be received, where the operation implements at least a portion of a signal analysis fimction. In other words, the user may select or invoke a signal operation, e.g., by right-clicking on a prior fimction block, signal plot or icon, thereby invoking a menu, or otherwise invoking presentation of selectable operations, and selecting the first operation therefrom. Then, prior operations input by the user may be programmatically analyzed to determine an input source for the first operation, where the input source provides a first input signal. In other words, operations that have already been specified previously by the user may be analyzed to find an operation that provides an output signal suitable for use as input to the first operation. For example, in one embodiment, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, and determining a prior operation of the prior operations that provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, where the prior operation includes the input source, and where the output signal includes the first input signal. In some embodiments, the first operation may require a plurality of inputs, and so programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more inputs required for the first operation and respective data types of each of the one or more inputs, and determining one or more prior operations of the prior operations that provide respective output signals of the respective data types, where the one or more prior operations include the input source, and where the respective output signals include the first input signal. In one embodiment, the method may also include assigning the output signal (or signals) of the appropriate signal type to the first operation as the first input signal. Said another way, once an output signal has been determined that is of the appropriate type, then the first operation may be configured to receive the determined output signal (or signals) as input. As noted above, in one embodiment, the first operation may correspond to a first function block. In this case, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may include querying the first function block to determine the one or more appropriate signal types for the first operation. Similarly, where the first operation requires a plurality of input signals, programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation may also include querying the first fuiction block to determine a number of inputs required for the first operation, and programmatically analyzing prior operations input by the user to determine a plurality of input sources for the first operation corresponding to the number of input signals required for the first operation. In another embodiment, determining a prior operation of the prior operations that provides an output signal of the appropriate signal type may include querying a database to determine the prior operation that provides an output signal of the appropriate signal type, where the database includes information indicating respective output signal types of the prior operations. It should be noted that in various embodiments, the database may be stored and accessed on the host computer, or on a computer coupled to the host computer, e.g., over a network, such as, for example, the Internet. In one embodiment, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include analyzing input/output (I/O) dependencies among the prior operations and the first operation, where the I/O dependencies indicate a proximity ordering of the prior operations with respect to the first operation, and then querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may include analyzing the prior operations regarding input signal types and sources, and output signal types and sources for the prior operations and the first operation to determine an ordering of the operations (proximity ordering) based on the input and output dependencies of the operations, where, for example, each operation is considered adjacent to another if the output of one is the input of the other. Thus, in one embodiment, the proximity ordering may reflect or correspond to a breadth first traversal of a dependency graph (in a computer science theoretic sense) for the set of operations. In an embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type further may include, for each of the plurality of input signals, querying the database based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as a prior operation is found that provides an output signal of the appropriate signal type. In other words, the method may iterate through the plurality of input signals for the first operation, and for each input signal, analyze the prior operations according to the proximity ordering to determine the prior operation (if any) that produces an output signal of the same type as (or a type compatible with) the input signal. In another embodiment where the first operation requires a plurality of input signals, and where each of the plurality of input signals has a respective signal type, querying the database to determine the prior operation that provides an output signal of the appropriate signal type may include iteratively querying the database regarding each of the prior operations to determine one or more prior operations that provide respective output signals of each of the respective signal types, based on the proximity ordering of the prior operations, beginning with an initial prior operation that is closest to the first operation with respect to I/O dependencies, and ending as soon as prior operations are found that provide respective output signals of the respective signal types or when there are no further prior operations to consider. In other words, the method may iterate over the prior operations according to the proximity ordering, querying the database regarding each operation and comparing the output signal (or signals) from the operation to determine whether the output signal is of the same as, or a compatible type with, any of the input signals of the first operation. As noted, in a preferred embodiment, the method may stop searching for an input source for a particular input signal of the first operation as soon an input source is found that provides an output signal of the appropriate type. Thus, an input source (or input sources) may be determined that provides signals suitable for input to the first operation. The first operation may then be performed on the first input signal received from the input source, thereby producing an output signal, where the first operation is preferably performed in a substantially continuous manner. Thus, the first operation may (in substantially continuous fashion) process signals from the determine input source and generate corresponding output signals. In response to performing the first operation, in one embodiment, the output signal may be displayed on a display, e.g., in a GUI displayed by a display device such as a computer monitor. For example, as described above, the output signal may be displayed in the display section of the GUI as a signal plot or graph, as tabular data, e.g., in a spreadsheet type format, and/or via other information display means, such as, for example, software-implemented indicators, e.g., gauges, meters, digital displays, and so forth. The method may determine whether there are additional operations to be specified by the user, e.g., based on user input, and, if no further operations are to be specified, the method may terminate. If the method determines that further operations are to be specified, then the method may repeat, proceeding as described above, where the programmatically analyzing, performing, and displaying may be performed for each of a plurality of first operations input by the user. In one embodiment, if none of the prior operations provides an output signal of the appropriate type, the method may facilitate selection of a different operation by the user as a signal source for the first operation. For example, programmatically analyzing prior operations input by the user to determine an input source for the first operation may include programmatically analyzing the first operation to determine one or more appropriate signal types for the first operation, determining whether any prior operation of the prior operations provides an output signal of an appropriate signal type, where the appropriate signal type includes one of the determined one or more appropriate signal types for the first operation, and, if any prior operation of the prior operations provides an output signal of an appropriate signal type, assigning the output signal of the appropriate signal type to the first operation as the first input signal, as described above. If no prior operations provide an output signal of an appropriate signal type, then one or more additional operations that provide an output signal of the appropriate signal type may be displayed, and additional user input received selecting an additional operation from the additional operations, where the additional operation includes the input source for the first operation, and where the output signal of the additional operation includes the first input signal. In other words, if a suitable prior operation cannot be found, additional operations may be presented to the user for selection, where the additional operations each preferably provide an output signal of the appropriate type for use as input to the first operation. Said another way, if no prior operation provides an output signal that is suitable for use as input by the first operation, the method may determine one or more other operations that provide a signal suitable for input to the first operation (e.g., that have not been previously included or selected by the user), and present these one or more other operations to the user for selection. For example, the one or more other operations may be presented in a palette, as options in a menu or dialog, or by any other means, as is well known in the art. In a preferred embodiment, upon selection (by the user) of an additional operation, the method may further include programmatically analyzing prior operations input by the user to determine an input source for the additional operation, where the input source provides an additional input signal, and performing the additional operation on the additional input signal received from the input source, thereby producing an additional output signal. In other words, once the additional (the other) operation is selected by the user, the method may attempt to automatically determine an input signal source for the additional operation, as described above with respect to the first operation. As mentioned above, in a preferred embodiment, the first operation and the prior operations each correspond to a respective function block. In one embodiment, the method may further include receiving user input modifying a configuration of a first function block, thereby changing input signal specifications for a corresponding operation, where original input signal specifications for the corresponding operation specify a first input signal type for the corresponding operation, and where the changed input signal specifications specify a second, different, input signal type for the corresponding operation. In other words, once one or more operations have been specified by the user, resulting in a corresponding one or more function blocks being displayed in the GUI (and the performance of the one or more operations), the user may provide input modifying one or more parameters for one of the function blocks, where the corresponding operation functions in accordance with the one or more parameters, and where the modified function block and corresponding operation require an input signal of the second, different, input signal type. Prior operations input by the user may then be programmatically analyzed to determine an input source for the corresponding operation, where the input source provides the second input signal of the second, different, input signal type, and the corresponding operation performed on the second input signal received from the input source for the corresponding operation, thereby producing a corresponding output signal. In one embodiment, the respective function blocks may be displayed in a diagram that visually represents I/O relationships between the function blocks, as described in some detail above. In one embodiment, when the I/O relationships between the function blocks change (e.g., as a result of modifying one or more of the function block/operation configurations, the addition or removal of an operation, etc.), the diagram may be automatically updated in accordance with the changed I/O relationships between the function blocks. For example, if the user modifies a function block/operation to receive a different type of input signal than was originally specified, and the method automatically determines an assigns a different input signal source (i.e., a different function block) than currently specified (replacing the original input source for that function block), the diagram may be automatically updated to reflect the new configuration of or I/O relationships between the function blocks. The techniques described above with respect to input signals for the first operation or function block may also be applied with respect to output signals. For example, in an embodiment where the first operation and each of the prior operations corresponds to a respective function block, the method may also include receiving user input modifying a configuration of a first function block, thereby changing output signal specifications for a corresponding operation, where original output signal specifications for the corresponding operation specify a first output signal type for the corresponding operation, and where the changed output signal specifications specify a second, different, output signal type for the corresponding operation. The prior operations input by the user may be programmatically analyzed to determine one or more function blocks configured to receive an output signal of the first function block according to the original output signal specifications, and if the one or more function blocks are configurable to receive the output signal according to the changed output signal specifications, the one or more function blocks may be configured to receive the output signal according to the changed output signal specifications. In one embodiment, if the one or more function blocks are not configurable to receive the output signal according to the changed output signal specifications, for each respective function block of the one or more function blocks, prior operations input by the user may be programmatically analyzed to determine an input source for the respective function block (e.g., to replace the original or current specified input signal), where the input source provides a respective input signal, and the corresponding operation of the respective function block performed on the respective input signal received from the input source, where said performing produces a respective output signal. In other words, if a function block or operation is modified to output a different type of signal (instead of the type originally or previously specified), then any function blocks that are currently configured to receive an input signal of the original type may require a different input signal source to provide an input signal of the appropriate type (e.g., of the original type or of a type compatible with the original type), and so the prior operations may be analyzed to determine suitable input signal sources for the function blocks. Similar to the above, once the results of the modifications have been propagated through the function blocks, the function block diagram is preferably updated automatically to reflect any changes in the I/O relationships between the function blocks. Thus, various embodiments of the systems and methods described above may operate to automatically determine input signal sources for selected function blocks or operations, thereby determining and/or modifying I/O relationships between the function blocks or operations, and optionally, to automatically update a function block diagram to reflect the I/O relationships. | 20040325 | 20070403 | 20050217 | 65728.0 | 0 | GUTIERREZ, ANTHONY | AUTOMATIC CONFIGURATION OF FUNCTION BLOCKS IN A SIGNAL ANALYSIS SYSTEM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,809,280 | ACCEPTED | System and methods for performing surgical procedures and assessments | The present invention involves systems and related methods for performing surgical procedures and assessments, including the use of neurophysiology-based monitoring to: (a) determine nerve proximity and nerve direction to surgical instruments employed in accessing a surgical target site; (b) assess the pathology (health or status) of a nerve or nerve root before, during, or after a surgical procedure; and/or (c) assess pedicle integrity before, during or after pedicle screw placement, all in an automated, easy to use, and easy to interpret fashion so as to provide a surgeon-driven system. | 1. A system for performing surgical procedures and assessments, comprising: a surgical accessory having at least one stimulation electrode; and a processing system having at least one of computer programming software, firmware and hardware capable of stimulating said at least one stimulation electrode on a surgical accessory, measuring the response of nerves depolarized by said stimulation, determining a relationship between the surgical accessory and the nerve based upon the response measured, and communicating said relationship to a user, wherein said relationship may be used to determine at least one of nerve proximity, nerve direction, pedicle integrity, and neural pathology. 2. The system set forth in claim 1 and further, wherein the response of said depolarized nerves is measured by monitoring the EMG waveforms of myotomes associated with said depolarized nerves. 3. The system set forth in claim 2 and further, wherein said surgical accessory comprises a system for establishing an operative corridor to a surgical target site. 4. The system set forth in claim 3 and further, wherein said system for establishing an operative corridor to a surgical target site includes a series of sequential dilator cannulae, each having at least one stimulation electrode near a distal end. 5. The system set forth in claim 3 and further, wherein said surgical target site is a spinal target site. 6. The system set forth in claim 5 and further, wherein said operative corridor may be established via a lateral, trans-psoas approach. 7. The system set forth in claim 1 and further, wherein said surgical accessory comprises a pedicle testing device including a handle and a pedicle probe. 8. The system set forth in claim 7 and further, wherein said pedicle testing device is capable of testing at least one of the interior of a hole formed in a pedicle and a pedicle screw after insertion into said hole. 9. The system set forth in claim 8 and further, wherein said handle includes at least one button for initiating the transmission of said stimulation signal from said processing system to said pedicle probe. 10. The system set forth in claim 1 and further, wherein said surgical accessory comprises a nerve root retractor capable of retracting a nerve and monitoring nerve function at least one of before, during, and after surgery. 11. The system set forth in claim 11 and further, wherein said nerve root retractor monitors nerve function through at least one of monopolar and bipolar stimulation of said retracted nerve. 12. The system set forth in claim 10 and further, wherein said nerve root retractor includes a handle and a detachable nerve root retractor blade. | CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation under 35 U.S.C. 111(a) of PCT Patent Application Ser. No. PCT/US02/30617, filed Sep. 25, 2002 and published on Apr. 3, 2003 as WO 03/026482 which is incorporated herein by reference. BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to a system and methods generally aimed at surgery. More particularly, the present invention is directed at a system and related methods for performing surgical procedures and assessments involving the use of neurophysiology. II. Description of Related Art A variety of surgeries involve establishing a working channel to gain access to a surgical target site. Oftentimes, based on the anatomical location of the surgical target site (as well as the approach thereto), the instruments required to form or create or maintain the working channel may have to pass near or close to nerve structures which, if contacted or disturbed, may be problematic to the patient. Examples of such “nerve sensitive” procedures may include, but are not necessarily limited to, spine surgery and prostrate or urology-related surgery. Systems and methods exist for monitoring nerves and nerve muscles. One such system determines when a needle is approaching a nerve. The system applies a current to the needle to evoke a muscular response. The muscular response is visually monitored, typically as a shake or “twitch.” When such a muscular response is observed by the user, the needle is considered to be near the nerve coupled to the responsive muscle. These systems require the user to observe the muscular response (to determine that the needle has approached the nerve). This may be difficult depending on the competing tasks of the user. In addition, when general anesthesia is used during a procedure, muscular response may be suppressed, limiting the ability of a user to detect the response. While generally effective (although crude) in determining nerve proximity, such existing systems are incapable of determining the direction of the nerve to the needle or instrument passing through tissue or passing by the nerves. This can be disadvantageous in that, while the surgeon may appreciate that a nerve is in the general proximity of the instrument, the inability to determine the direction of the nerve relative to the instrument can lead to guess work by the surgeon in advancing the instrument and thereby raise the specter of inadvertent contact with, and possible damage to, the nerve. Another nerve-related issue in existing surgical applications involves the use of nerve retractors. A typical nerve retractor serves to pull or otherwise maintain the nerve outside the area of surgery, thereby protecting the nerve from inadvertent damage or contact by the “active” instrumentation used to perform the actual surgery. While generally advantageous in protecting the nerve, it has been observed that such retraction can cause nerve function to become impaired or otherwise pathologic over time due to the retraction. In certain surgical applications, such as spinal surgery, it is not possible to determine if such retraction is hurting or damaging the retracted nerve until after the surgery (generally referred to as a change in “nerve health” or “nerve status”). There are also no known techniques or systems for assessing whether a given procedure is having a beneficial effect on a nerve or nerve root known to be pathologic (that is, impaired or otherwise unhealthy). In spinal surgery, and specifically in spinal fusion procedures, a still further nerve-related issue exists with regard to assessing the placement of pedicle screws. More specifically, it has been found desirable to detect whether the medial wall of a pedicle has been breached (due to the formation of the hole designed to receive a pedicle screw or due to the placement of the pedicle screw into the hole) while attempting to effect posterior fixation for spinal fusion through the use of pedicle screws. Various attempts have been undertaken at assessing the placement of pedicle screws. X-ray and other imaging systems have been employed, but these are typically quite expensive and are oftentimes limited in terms of resolution (such that pedicle breaches may fail to be detected). Still other attempts involve capitalizing on the insulating characteristics of bone (specifically, that of the medial wall of the pedicle) and the conductivity of the exiting nerve roots themselves. That is, if the medial wall of the pedicle is breached, a stimulation signal (voltage or current) applied to the pedicle screw and/or the pre-formed hole (prior to screw introduction) will cause the various muscle groups coupled to the exiting nerve roots to twitch. If the pedicle wall has not been breached, the insulating nature of the medial wall will prevent the stimulation signal from innervating the given nerve roots such that the muscle groups will not twitch. To overcome this obviously crude technique (relying on visible muscles twitches), it has been proposed to employ electromyographic (EMG) monitoring to assess whether the muscle groups in the leg are innervating in response to the application of a stimulation signal to the pedicle screw and/or the pre-formed hole. This is advantageous in that it detects such evoked muscle action potentials (EMAPs) in the leg muscles as much lower levels than that via the “visual inspection” technique described above. However, the traditional EMG systems employed to date suffer from various drawbacks. First, traditional EMG systems used for pedicle screw testing are typically quite expensive. More importantly, they produce multiple waveforms that must be interpreted by a neurophysiologist. Even though performed by specialists, interpreting such multiple EMG waveforms in this fashion is nonetheless disadvantageously prone to human error and can be disadvantageously time consuming, adding to the duration of the operation and translating into increased health care costs. Even more costly is the fact that the neurophysiologist is required in addition to the actual surgeon performing the spinal operation. The present invention is directed at eliminating, or at least reducing the effects of, the above-described problems with the prior art. SUMMARY OF THE INVENTION The present invention includes a system and related methods for performing surgical procedures and assessments, including the use of neurophysiology-based monitoring to: (a) determine nerve proximity and nerve direction to surgical instruments employed in accessing a surgical target site; (b) assess the pathology (health or status) of a nerve or nerve root before, during, or after a surgical procedure; and/or (c) assess pedicle integrity before, during or after pedicle screw placement, all in an automated, easy to use, and easy to interpret fashion so as to provide a surgeon-driven system. The present invention accomplishes this by combining neurophysiology monitoring with any of a variety of instruments used in or in preparation for surgery (referred to herein as “surgical accessories”). By way of example only, such surgical accessories may include, but are not necessarily limited to, any number of devices or components for creating an operative corridor to a surgical target site (such as K-wires, sequentially dilating cannula systems, distractor systems, and/or retractor systems), devices or components for assessing pedicle integrity (such as a pedicle testing probe), and/or devices or components for retracting or otherwise protecting a nerve root before, during and/or after surgery (such as a nerve root retractor). Although described herein largely in terms of use in spinal surgery, it is to be readily appreciated that the teachings of the method and apparatus of the present invention are suitable for use in any number of additional surgical procedures wherein tissue having significant neural structures must be passed through (or near) in order to establish an operative corridor to a surgical target site, wherein neural structures are located adjacent bony structures, and/or wherein neural structures are retracted or otherwise contacted during surgery. The fundamental method steps according to the present invention include: (a) stimulating one or more electrodes provided on a surgical accessory; (b) measuring the response of nerves innervated by the stimulation of step (a); (c) determining a relationship between the surgical accessory and the nerve based upon the response measured in step (b); and communicating this relationship to the surgeon in an easy-to-interpret fashion. The step of stimulating may be accomplished by applying any of a variety of suitable stimulation signals to the electrode(s) on the surgical accessory, including voltage and/or current pulses of varying magnitude and/or frequency. The stimulating step may be performed at different times depending upon the particular surgical accessory in question. For example, when employed with a surgical access system, stimulation may be performed during and/or after the process of creating an operative corridor to the surgical target site. When used for pedicle integrity assessments, stimulation may be performed before, during and/or after the formation of the hole established to receive a pedicle screw, as well as before, during and/or after the pedicle screw is introduced into the hole. With regard to neural pathology monitoring, stimulation may be performed before, during and/or after retraction of the nerve root. The step of measuring the response of nerves innervated by the stimulation step may be performed in any number of suitable fashions, including but not limited to the use of evoked muscle action potential (EMAP) monitoring techniques (that is, measuring the EMG responses of muscle groups associated with a particular nerve). According to one aspect of the present invention, the measuring step is preferably accomplished via monitoring or measuring the EMG responses of the muscles innervated by the nerve(s) stimulated in step for each of the preferred functions of the present invention: surgical access, pedicle integrity assessments, and neural pathology monitoring. The step of determining a relationship between the surgical accessory and the nerve based upon the measurement step may be performed in any number of suitable fashions depending upon the manner of measuring the response, and may define the relationship in any of a variety of fashions (based on any number of suitable parameters and/or characteristics). By way of example only, the step of determining a relationship, within the context of a surgical access system, may involve identifying when (and preferably the degree to which) the surgical accessory comes into close proximity with a given nerve (“nerve proximity”) and/or identifying the relative direction between the surgical accessory and the nerve (“nerve direction”). For a pedicle integrity assessment, the relationship between the surgical accessory (screw test probe) and the nerve is whether electrical communication is established therebetween. If electrical communication is established, this indicates that the medial wall of the pedicle has been cracked, stressed, or otherwise breached during the steps of hole formation and/or screw introduction. If not, this indicates that the integrity of the medial wall of the pedicle has remained intact during hole formation and/or screw introduction. This characteristic is based on the insulating properties of bone. For neural pathology assessments according to the present invention, the relationship may be, by way of example only, whether the neurophysiologic response of the nerve has changed over time. Such neurophysiologic responses may include, but are not necessarily limited to, the onset stimulation threshold for the nerve in question, the slope of the response vs. the stimulation signal for the nerve in question and/or the saturation level of the nerve in question. Changes in these parameters will indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery. The step of communicating this relationship to the surgeon in an easy-to-interpret fashion may be accomplished in any number of suitable fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics) and audio communications (such as a speaker element). By way of example only, with regard to surgical access systems, this step of communicating the relationship may include, but is not necessarily limited to, visually representing the stimulation threshold of the nerve (indicating relative distance or proximity to the nerve), providing color coded graphics to indicate general proximity ranges (i.e. “green” for a range of stimulation thresholds above a predetermined safe value, “red” for range of stimulation thresholds below a predetermined unsafe value, and “yellow” for the range of stimulation thresholds in between the predetermined safe and unsafe values—designating caution), as well as providing an arrow or other suitable symbol for designating the relative direction to the nerve. This is an important feature of the present invention in that, by providing such proximity and direction information, a user will be kept informed as to whether a nerve is too close to a given surgical accessory element during and/or after the operative corridor is established to the surgical target site. This is particularly advantageous during the process of accessing the surgical target site in that it allows the user to actively avoid nerves and redirect the surgical access components to successfully create the operative corridor without impinging or otherwise compromising the nerves. Based on these nerve proximity and direction features, then, the present invention is capable of passing through virtually any tissue with minimal (if any) risk of impinging or otherwise damaging associated neural structures within the tissue, thereby making the present invention suitable for a wide variety of surgical applications. With regard to pedicle integrity assessments, the step of communicating the relationship may include, but is not necessarily limited to, visually representing the actual stimulation threshold of an exiting nerve root alone or in combination with the stimulation threshold of a bare nerve root (with or without the difference therebetween), as well as with providing color coded graphics to indicate general ranges of pedicle integrity (i.e. “green” for a range of stimulation thresholds above a predetermined safe value—indicating “breach unlikely”, “red” for range of stimulation thresholds below a predetermined unsafe value—indicating “breach likely”, and “yellow” for the range of stimulation thresholds between the predetermined safe and unsafe values—indicating “possible breach”). This is a significant feature, and advantage over the prior art, in that it provides a straightforward and easy to interpret representation as to whether a pedicle has been breached during and/or after the process of forming the hole and/or introducing the pedicle screw. Identifying such a potential breach is helpful in that it prevents or minimizes the chance that a misplaced pedicle screw (that is, one breaching the medial wall) will be missed until after the surgery. Instead, any such misplaced pedicle screws, when stimulated according to the present invention, will produce an EMG response at a myotome level associated with the nerve in close proximity to the pedicle screw that is breaching the pedicle wall. This will indicate to the surgeon that the pedicle screw needs to be repositioned. But for this system and technique, patients may be released and subsequently experience pain due to the contact between the exiting nerve root and the pedicle screw, which oftentimes requires another costly and painful surgery. As for neural pathology monitoring, the step of communicating the relationship may include, but is not necessarily limited to, visually representing the changes over time in the onset stimulation threshold of the nerve, the slope of the response versus the stimulation threshold of the nerve and/or the saturation level of the nerve. Once again, these changes may indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery and/or retraction. This feature is important in that it may provide qualitative feedback on the effect of the particular surgery. If it appears the health or status (pathology) of the nerve is deteriorating over time, the user may be instructed to stop or lessen the degree of retraction to avoid such deterioration. If the pathology of the nerve improves over time, it may indicate the success of the surgery in restoring or improving nerve function, such as may be the case in decompressive spinal surgery. The present invention also encompasses a variety of techniques, algorithms, and systems for accomplishing the steps of (a) stimulating one or more electrodes provided on a surgical accessory; (b) measuring the response of nerves innervated by the stimulation of step (a); (c) determining a relationship between the surgical accessory and the nerve based upon the response measured in step (b); and/or communicating this relationship to the surgeon in an easy-to-interpret fashion. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart illustrating the fundamental steps of the neurophysiology-based surgical system according to the present invention; FIG. 2 is a perspective view of an exemplary surgical system 20 capable of determining nerve proximity and direction to surgical instruments employed in accessing a surgical target site, assessing pedicle integrity before, during or after pedicle screw placement, and/or assessing the pathology (health and/or status) of a nerve or nerve root before, during, or after a surgical procedure; FIG. 3 is a block diagram of the surgical system 20 shown in FIG. 2; FIG. 4 is a graph illustrating a plot of a stimulation current pulse capable of producing a neuromuscular response (EMG) of the type shown in FIG. 3; FIG. 5 is a graph illustrating a plot of the neuromuscular response (EMG) of a given myotome over time based on a current stimulation pulse (such as shown in FIG. 4) applied to a nerve bundle coupled to the given myotome; FIG. 6 is an illustrating (graphical and schematic) of a method of automatically determining the maximum frequency (FMax) of the stimulation current pulses according to one embodiment of the present invention; FIG. 7 is a graph illustrating a plot of EMG response peak-to-peak voltage (Vpp) for each given stimulation current level (IStim) forming a stimulation current pulse according to the present invention (otherwise known as a “recruitment curve”); FIG. 8 is a graph illustrating a traditional stimulation artifact rejection technique as may be employed in obtaining each peak-to-peak voltage (Vpp) EMG response according to the present invention; FIG. 9 is a graph illustrating the traditional stimulation artifact rejection technique of FIG. 8, wherein a large artifact rejection causes the EMG response to become compromised; FIG. 10 is a graph illustrating an improved stimulation artifact rejection technique according to the present invention; FIG. 11 is a graph illustrating an improved noise artifact rejection technique according to the present invention; FIG. 12 is a graph illustrating a plot of a neuromuscular response (EMG) over time (in response to a stimulus current pulse) showing the manner in which voltage extrema (VMax or Min), (VMin or Max) occur at times T1 and T2, respectively; FIG. 13 is a graph illustrating a histogram as may be employed as part of a T1, T2 artifact rejection technique according to an alternate embodiment of the present invention; FIGS. 14A-14E are graphs illustrating a current threshold-hunting algorithm according to one embodiment of the present invention; FIG. 15 is a series of graphs illustrating a multi-channel current threshold-hunting algorithm according to one embodiment of the present invention; FIGS. 16-19 are top views of a neurophysiology-based surgical access system according to one embodiment of the present invention in use accessing a surgical target site in the spine; FIG. 20 is an exemplary screen display illustrating one embodiment of the nerve proximity or detection feature of the surgical access system of the present invention; FIG. 21 is an exemplary screen display illustrating one embodiment of the nerve detection feature of the surgical access system of the present invention; FIG. 22 is a graph illustrating a method of determining the direction of a nerve (denoted as an “octagon”) relative to an instrument having four (4) orthogonally disposed stimulation electrodes (denoted by the “circles”) according to one embodiment of the present invention; FIGS. 23-24 are exemplary screen displays illustrating one embodiment of the pedicle integrity assessment feature of the present invention; FIGS. 25-27 are exemplary screen displays illustrating another embodiment of the pedicle integrity assessment feature of the present invention; FIG. 28 is a graph illustrating recruitment curves for a generally healthy nerve (denoted “A”) and a generally unhealthy nerve (denoted “B”) according to the nerve pathology monitoring feature of the present invention; FIGS. 29-30 are perspective and side views, respectively, of an exemplary nerve root retractor assembly according to one embodiment of the present invention; FIG. 31 is a perspective view of an exemplary nerve root retractor according to one embodiment of the present invention; FIG. 32 is an exemplary screen display illustrating one embodiment of the neural pathology monitoring feature of the present invention, specifically for monitoring change in nerve function of a healthy nerve due to nerve retraction; FIG. 33 is an exemplary screen display illustrating another embodiment of the neural pathology monitoring feature of the present invention, specifically for monitoring change in nerve function of a healthy nerve due to nerve retraction; FIG. 34 is an exemplary screen display illustrating one embodiment of the neural pathology monitoring feature of the present invention, specifically for monitoring change in nerve function of an unhealthy nerve due to the performance of a surgical procedure; and FIG. 35 is an exemplary screen display illustrating another embodiment of the neural pathology monitoring feature of the present invention, specifically for monitoring change in nerve function of an unhealthy nerve due to the performance of a surgical procedure. DESCRIPTION OF THE SPECIFIC EMBODIMENTS Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The systems disclosed herein boast a variety of inventive features and components that warrant patent protection, both individually and in combination. The present invention is capable of performing a variety of surgical procedures and assessments by combining neurophysiology monitoring with any of a variety of instruments used in or in preparation for surgery (referred to herein as “surgical accessories”). By way of example only, such surgical accessories may include, but are not necessarily limited to, any number of devices or components for creating an operative corridor to a surgical target site (such as K-wires, sequentially dilating cannula systems, distractor systems, and/or retractor systems), for retracting or otherwise protecting a nerve root before, during and/or after surgery (such as a nerve root retractor), and/or for assessing pedicle integrity (such as a pedicle screw test probe). Although described herein largely in terms of use in spinal surgery, it is to be readily appreciated that the teachings of the method and apparatus of the present invention are suitable for use in any number of additional surgical procedures wherein tissue having significant neural structures must be passed through (or near) in order to establish an operative corridor to a surgical target site, wherein neural structures are retracted, and/or wherein neural structures are located adjacent bony structures. FIG. 1 illustrates the fundamental method steps according to the present invention, namely: (a) stimulating one or more electrodes provided on a surgical accessory; (b) measuring the response of nerves innervated by the stimulation of step (a); (c) determining a relationship between the surgical accessory and the nerve based upon the response measured in step (b); and (d) communicating this relationship to the surgeon in an easy-to-interpret fashion. The step of stimulating may be accomplished by applying any of a variety of suitable stimulation signals to the electrode(s) on the surgical accessory, including voltage and/or current pulses of varying magnitude and/or frequency. The stimulating step may be performed at different times depending upon the particular surgical accessory in question. For example, when employed with a surgical access system, stimulation 10 may be performed during and/or after the process of creating an operative corridor to the surgical target site. When used for pedicle integrity assessments, stimulation 10 may be performed before, during and/or after the formation of the hole established to receive a pedicle screw, as well as before, during and/or after the pedicle screw is introduced into the hole. With regard to neural pathology monitoring, stimulation 10 may be performed before, during and/or after retraction of the nerve root. The step of measuring the response of nerves innervated by the stimulation step 10 may be performed in any number of suitable fashions, including but not limited to the use of evoked muscle action potential (EMAP) monitoring techniques (that is, measuring the EMG responses of muscle groups associated with a particular nerve). According to one aspect of the present invention, the measuring step is preferably accomplished via monitoring or measuring the EMG responses of the muscles innervated by the nerve(s) stimulated in step (a) for each of the preferred functions of the present invention: surgical access, pedicle integrity assessments, and neural pathology monitoring. The step of determining a relationship between the surgical accessory and the nerve based upon the measurement step (b) may be performed in any number of suitable fashions depending upon the manner of measuring the response of step (b), and may define the relationship in any of a variety of fashions (based on any number of suitable parameters and/or characteristics). By way of example only, step (c) of determining a relationship, within the context of a surgical access system, may involve identifying when (and preferably the degree to which) the surgical accessory comes into close proximity with a given nerve (“nerve proximity”) and/or identifying the relative direction between the surgical accessory and the nerve (“nerve direction”). For a pedicle integrity assessment, the relationship between the surgical accessory (screw test probe) and the nerve is whether electrical communication is established therebetween. If electrical communication is established, this indicates that the medial wall of the pedicle has been cracked, stressed, or otherwise breached during the steps of hole formation and/or screw introduction. If not, this indicates that the integrity of the medial wall of the pedicle has remained intact during hole formation and/or screw introduction. This characteristic is based on the insulating properties of bone. For neural pathology assessments according to the present invention, the step (c) relationship may be, by way of example only, whether the neurophysiologic response of the nerve has changed over time. Such neurophysiologic responses may include, but are not necessarily limited to, the onset stimulation threshold for the nerve in question, the slope of the response vs. the stimulation signal for the nerve in question and/or the saturation level of the nerve in question. Changes in these parameters will indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery. The step of communicating this relationship to the surgeon in an easy-to-interpret fashion may be accomplished in any number of suitable fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics) and audio communications (such as a speaker element). By way of example only, with regard to surgical access systems, step (d) of communicating the relationship may include, but is not necessarily limited to, visually representing the stimulation threshold of the nerve (indicating relative distance or proximity to the nerve), providing color coded graphics to indicate general proximity ranges (i.e. “green” for a range of stimulation thresholds above a predetermined safe value, “red” for range of stimulation thresholds below a predetermined unsafe value, and “yellow” for the range of stimulation thresholds in between the predetermined safe and unsafe values—designating caution), as well as providing an arrow or other suitable symbol for designating the relative direction to the nerve. This is an important feature of the present invention in that, by providing such proximity and direction information, a user will be kept informed as to whether a nerve is too close to a given surgical accessory element during and/or after the operative corridor is established to the surgical target site. This is particularly advantageous during the process of accessing the surgical target site in that it allows the user to actively avoid nerves and redirect the surgical access components to successfully create the operative corridor without impinging or otherwise compromising the nerves. Based on these nerve proximity and direction features, then, the present invention is capable of passing through virtually any tissue with minimal (if at all) risk of impinging or otherwise damaging associated neural structures within the tissue, thereby making the present invention suitable for a wide variety of surgical applications. With regard to pedicle integrity assessments, step (d) of communicating the relationship may include, but is not necessarily limited to, visually representing the actual stimulation threshold of an exiting nerve root alone or in combination with the stimulation threshold of a bare nerve root (with or without the difference therebetween), as well as with providing color coded graphics to indicate general ranges of pedicle integrity (i.e. “green” for a range of stimulation thresholds above a predetermined safe value—indicating “breach unlikely”, “red” for range of stimulation thresholds below a predetermined unsafe value—indicating “breach likely”, and “yellow” for the range of stimulation thresholds between the predetermined safe and unsafe values—indicating “possible breach”). This is a significant feature, and advantage over the prior art, in that it provides a straightforward and easy to interpret representation as to whether a pedicle has been breached during and/or after the process of forming the hole and/or introducing the pedicle screw. Identifying such a potential breach is helpful in that it prevents or minimizes the chance that a misplaced pedicle screw (that is, one breaching a wall of the pedicle, such as, by way of example, the medial wall) will be missed until after the surgery. Instead, any such misplaced pedicle screws, when stimulated according to the present invention, will produce an EMG response at a myotome level associated with the nerve in close proximity to the pedicle screw that is breaching the pedicle wall. This will indicate to the surgeon that the pedicle screw needs to be repositioned. But for this system and technique, patients may be released and subsequently experience pain due to the contact between the exiting nerve root and the pedicle screw, which oftentimes requires another costly and painful surgery. As for neural pathology monitoring, step (d) of communicating the relationship may include, but is not necessarily limited to, visually representing the changes over time in the onset stimulation threshold of the nerve, the slope of the response versus the stimulation threshold of the nerve and/or the saturation level of the nerve. Once again, these changes may indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery and/or retraction. This feature is important in that it may provide qualitative feedback on the effect of the particular surgery. If it appears the health or status (pathology) of the nerve is deteriorating over time, the user may be instructed to stop or lessen the degree of retraction to avoid such deterioration. If the pathology of the nerve improves over time, it may indicate the success of the surgery in restoring or improving nerve function, such as may be the case in decompressive spinal surgery. FIGS. 2-3 illustrate, by way of example only, a surgical system 20 provided in accordance with a broad aspect of the present invention. The surgical system 20 includes a control unit 22, a patient module 24, an EMG harness 26 and return electrode 28 coupled to the patient module 24, and a host of surgical accessories 30 capable of being coupled to the patient module 24 via one or more accessory cables 32. In the embodiment shown, the surgical accessories 30 include (by way of example only) a sequential dilation access system 34, a pedicle testing assembly 36, and a nerve root retractor assembly 38. The control unit 22 includes a touch screen display 40 and a base 42, which collectively contain the essential processing capabilities for controlling the surgical system 20. The patient module 24 is connected to the control unit 22 via a data cable 44, which establishes the electrical connections and communications (digital and/or analog) between the control unit 22 and patient module 24. The main functions of the control unit 22 include receiving user commands via the touch screen display 40, activating stimulation in the requested mode (nerve proximity, nerve direction, screw test, and nerve pathology), processing signal data according to defined algorithms (described below), displaying received parameters and processed data, and monitoring system status and report fault conditions. The touch screen display 40 is preferably equipped with a graphical user interface (GUI) capable of communicating information to the user and receiving instructions from the user. The display 40 and/or base 42 may contain patient module interface circuitry that commands the stimulation sources, receives digitized signals and other information from the patient module 24, processes the EMG responses to extract characteristic information for each muscle group, and displays the processed data to the operator via the display 40. As will be described in greater detail below, the surgical system 20 is capable of performing one or more of the following functions: (1) determination of nerve proximity and/or nerve direction relative to the sequential dilation access system 34 during and following the creation of an operative corridor to surgical target site; (2) assessment of pedicle integrity after hole formation and/or after pedicle screw placement via the pedicle testing assembly 36; and/or (3) assessment of nerve pathology (health or status) before, during, and/or after a surgical procedure via the nerve root retractor assembly 38. Surgical system 20 accomplishes this by having the control unit 22 and patient module 24 cooperate to send stimulation signals to one or more stimulation electrodes on the various surgical accessories 30. Depending upon the location of the surgical accessories within a patient, the stimulation signals may cause nerves adjacent to or in the general proximity of the surgical accessories 30 to innervate, which, in turn, can be monitored via the EMG harness 26. The nerve proximity and direction, pedicle integrity, and nerve pathology features of the present invention are based on assessing the evoked response of the various muscle myotomes monitored by the surgical system 20 via EMG harness 26. The sequential dilation access system 34 comprises, by way of example only, a K-wire 46, one or more dilating cannula 48, and a working cannula 50. As will be explained in greater detail below, these components 46-50 are designed to bluntly dissect the tissue between the patient's skin and the surgical target site. In an important aspect of the present invention, the K-wire 46, dilating cannula 48 and/or working cannula 50 may be equipped with one or more stimulation electrodes to detect the presence and/or location of nerves in between the skin of the patient and the surgical target site. To facilitate this, a surgical hand-piece 52 is provided for electrically coupling the surgical accessories 46-50 to the patient module 24 (via accessory cable 32). In a preferred embodiment, the surgical hand piece 42 includes one or more buttons for selectively initiating the stimulation signal (preferably, a current signal) from the control unit 12 to a particular surgical access component 46-50. Stimulating the electrode(s) on these surgical access components 46-50 during passage through tissue in forming the operative corridor will cause nerves that come into close or relative proximity to the surgical access components 46-50 to depolarize, producing a response in the innervated myotome. By monitoring the myotomes associated with the nerves (via the EMG harness 26 and recording electrode 27) and assessing the resulting EMG responses (via the control unit 22), the sequential dilation access system 34 is capable of detecting the presence (and optionally direction to) such nerves, thereby providing the ability to actively negotiate around or past such nerves to safely and reproducibly form the operative corridor to a particular surgical target site. In one embodiment, the sequential dilation access system 34 is particularly suited for establishing an operative corridor to an intervertebral target site in a postero-lateral, trans-psoas fashion so as to avoid the bony posterior elements of the spinal column. The pedicle testing assembly 36 includes a surgical accessory handle assembly 54 and a pedicle probe 56. The handle assembly 54 includes a cable 55 for establishing electrical communication with the patient module 24 (via the accessory cable 32). In a preferred embodiment, the pedicle probe 56 may be selectively removed from the handle assembly 54, such as by unscrewing a threaded cap 58 provided on the distal end of the handle assembly 54 (through which the proximal end of the pedicle probe 56 passes). The pedicle probe 56 includes a ball-tipped distal end 60 suitable for introduction into a pedicle hole (after hole formation but before screw insertion) and/or for placement on the head of a fully introduced pedicle screw. In both situations, the user may operate one or more buttons of the handle assembly 54 to selectively initiate a stimulation signal (preferably, a current signal) from the patient module 24 to the pedicle probe 56. With the pedicle probe 56 touching the inner wall of the pedicle hole and/or the fully introduced pedicle screw, applying a stimulation signal in this fashion serves to test the integrity of the medial wall of the pedicle. That is, a breach or compromise in the integrity of the pedicle will allow the stimulation signal to pass through the pedicle and innervate an adjacent nerve root. By monitoring the myotomes associated with the nerve roots (via the EMG harness 26 and recording electrode 27) and assessing the resulting EMG responses (via the control unit 22), the surgical system 20 can assess whether a pedicle breach occurred during hole formation and/or screw introduction. If a breach or potential breach is detected, the user may simply withdraw the misplaced pedicle screw and redirect to ensure proper placement. The nerve root retractor assembly 38, in a preferred embodiment, comprises the same style surgical accessory handle assembly 54 as employed with in the pedicle testing assembly 36, with a selectively removable nerve root retractor 62. The nerve root retractor 62 has a generally angled orientation relative to the longitudinal axis of the handle assembly 54, and includes a curved distal end 64 having a generally arcuate nerve engagement surface 66 equipped with one or more stimulation electrodes (not shown). In use, the nerve root retractor 62 is introduced into or near a surgical target site in order to hook and retract a given nerve out of the way. According to the present invention, the nerve root may be stimulated (monopolar or bipolar) before, during, and/or after retraction in order to assess the degree to which such retraction impairs or otherwise degrades nerve function over time. To do so, the user may operate one or more buttons of the handle assembly 54 to selectively transmit a stimulation signal (preferably, a current signal) from the patient module 24 to the electrode(s) on the engagement surface 66 of the nerve root retractor 62. By monitoring the myotome associated with the nerve root being retracted (via the EMG harness 26) and assessing the resulting EMG responses (via the control unit 22), the surgical system 20 can assess whether (and the degree to which) such retraction impairs or adversely affects nerve function over time. With this information, a user may wish to periodically release the nerve root from retraction to allow nerve function to recover, thereby preventing or minimizing the risk of long-term or irreversible nerve impairment. As will be described in greater detail below, a similar neural pathology assessment can be undertaken, whereby an unhealthy nerve may be monitored to determine if nerve function improves due to a particular surgical procedure, such as spinal nerve decompression surgery. A discussion of the algorithms and principles behind the neurophysiology for accomplishing these functions will now be undertaken, followed by a detailed description of the various implementations of these principles according to the present invention. FIGS. 4 and 5 illustrate a fundamental aspect of the present invention: a stimulation signal (FIG. 4) and a resulting evoked response (FIG. 5). By way of example only, the stimulation signal is preferably a stimulation current signal (IStim) having rectangular monophasic pulses with a frequency and amplitude adjusted by system software. In a still further preferred embodiment, the stimulation current (IStim) may be coupled in any suitable fashion (i.e. AC or DC) and comprises rectangular monophasic pulses of 200 microsecond duration. The amplitude of the current pulses may be fixed, but will preferably sweep from current amplitudes of any suitable range, such as from 2 to 100 mA. For each nerve and myotome there is a characteristic delay from the stimulation current pulse to the EMG response (typically between 5 to 20 ms). To account for this, the frequency of the current pulses is set at a suitable level such as, in a preferred embodiment, 4 Hz to 10 Hz (and most preferably 4.5 Hz), so as to prevent stimulating the nerve before it has a chance to recover from depolarization. The EMG response shown in FIG. 5 can be characterized by a peak-to-peak voltage of Vpp=Vmax−Vmin. FIG. 6 illustrates an alternate manner of setting the maximum stimulation frequency, to the extent it is desired to do so rather than simply selecting a fixed maximum stimulation frequency (such as 4.5 Hz) as described above. According to this embodiment, the maximum frequency of the stimulation pulses is automatically adjusted. After each stimulation, Fmax will be computed as: Fmax=1/(T2+TSafety Margin) for the largest value of T2 from each of the active EMG channels. In one embodiment, the Safety Margin is 5 ms, although it is contemplated that this could be varied according to any number of suitable durations. Before the specified number of stimulations, the stimulations will be performed at intervals of 100-120 ms during the bracketing state, intervals of 200-240 ms during the bisection state, and intervals of 400-480 ms during the monitoring state. After the specified number of stimulations, the stimulations will be performed at the fastest interval practical (but no faster than Fmax) during the bracketing state, the fastest interval practical (but no faster than Fmax/2) during the bisection state, and the fastest interval practical (but no faster than Fmax/4) during the monitoring state. The maximum frequency used until Fmax is calculated is preferably 10 Hz, although slower stimulation frequencies may be used during some acquisition algorithms. The value of Fmax used is periodically updated to ensure that it is still appropriate. For physiological reasons, the maximum frequency for stimulation will be set on a per-patient basis. Readings will be taken from all myotomes and the one with the slowest frequency (highest T2) will be recorded. A basic premise behind the neurophysiology employed in the present invention is that each nerve has a characteristic threshold current level (IThresh) at which it will depolarize. Below this threshold, current stimulation will not evoke a significant EMG response (Vpp). Once the stimulation threshold (IThresh) is reached, the evoked response is reproducible and increases with increasing stimulation until saturation is reached. This relationship between stimulation current and EMG response may be represented graphically via a so-called “recruitment curve,” such as shown in FIG. 7, which includes an onset region, a linear region, and a saturation region. By way of example only, the present invention defines a significant EMG response to have a Vpp of approximately 100 uV. In a preferred embodiment, the lowest stimulation current that evokes this threshold voltage (VThresh) is called IThresh. As will be described in greater detail below, changes in the current threshold (IThresh) over time may indicate that the relative distance between the nerve and the stimulation electrode is changing (indicating nerve migration towards the surgical accessory having the stimulation electrode and/or movement of the surgical accessory towards the nerve). This is useful in performing proximity assessments between the electrode and the nerve according to an aspect of the present invention. Changes in the current threshold (IThresh) may also be indicative of a change in the degree of electrical communication between a stimulation electrode and a nerve. This may be helpful, by way of example, in assessing if a screw or similar instrument has inadvertently breached the medial wall of a pedicle. More specifically, where an initial determination of (IThresh), such as by applying a stimulation current to the interior of a hole created to receive a pedicle screw, is greater than a later determination of (IThresh), such as by applying a stimulation current to the tip of the pedicle screw after insertion, the decrease in IThresh, if large enough, may indicate electrical communication between the pedicle screw and the nerve. Based on the insulation properties of bone, such electrical communication would indicate a breach of the pedicle. As will also be in greater detail below, changes in the current threshold (IThresh), the slope of the linear region, and the saturation level over time are indicative of changes in the pathology (that is, health or status) of a given nerve. This is useful in assessing the effects of surgery on an unhealthy nerve (such as decompression surgery) as well as assessing the effects of nerve retraction on a healthy nerve (so as to prevent or minimize the risk of damage due to retraction). In order to obtain this useful information, the present invention must first identify the peak-to-peak voltage (Vpp) of each EMG response corresponding a given stimulation current (IStim). The existence stimulation and/or noise artifacts, however, can conspire to create an erroneous Vpp measurement of the electrically evoked EMG response. To overcome this challenge, the surgical system 20 of the present invention may employ any number of suitable artifact rejection techniques, including the traditional stimulation artifact rejection technique shown in FIG. 8. Under this technique, stimulation artifact rejection is undertaken by providing a simple artifact rejection window T1WIN at the beginning of the EMG waveform. During this T1 window, the EMG waveform is ignored and Vpp is calculated based on the max and min values outside this window. (T1 is the time of the first extremum (min or max) and T2 is the time of the second extremum.) In one embodiment, the artifact rejection window T1WIN may be set to about 7.3 msec. While generally suitable, there are situations where this stimulation artifact rejection technique of FIG. 8 is not optimum, such as in the presence of a large stimulation artifact (see FIG. 9). The presence of a large stimulation artifact causes the stimulation artifact to cross over the window T1WIN and blend in with the EMG. Making the stimulation artifact window larger is not effective, since there is no clear separation between EMG and stimulation artifact. FIG. 10 illustrates a stimulation artifact rejection technique according to the present invention, which solves the above-identified problem with traditional stimulation artifact rejection. Under this technique, a T1 validation window (T1-VWIN) is defined immediately following the T1 window (T1WIN). If the determined Vpp exceeds the threshold for recruiting, but T1 falls within this T1 validation window, then the stimulation artifact is considered to be substantial and the EMG is considered to have not recruited. An operator may be alerted, based on the substantial nature of the stimulation artifact. This method of stimulation artifact rejection is thus able to identify situations where the stimulation artifact is large enough to cause the Vpp to exceed the recruit threshold. To account for noise, the T1 validation window (T1-VWIN) should be within the range of 0.1 ms to 1 ms wide (preferably about 0.5 ms). The T1 validation window (T1-VWIN) should not be so large that the T1 from an actual EMG waveform could fall within. FIG. 11 illustrates a noise artifact rejection technique according to the present invention. When noise artifacts fall in the time window where an EMG response is expected, their presence can be difficult to identify. Artifacts outside the expected response window, however, are relatively easy to identify. The present invention capitalizes on this and defines a T2 validation window (T2-VWIN) analogous to the T1 validation window (T1-VWIN) described above with reference to FIG. 10. As shown, T2 must occur prior to a defined limit, which, according to one embodiment of the present invention, may be set having a range of between 40 ms to 50 ms (preferably about 47 ms). If the Vpp of the EMG response exceeds the threshold for recruiting, but T2 falls beyond the T2 validation window (T2-VWIN), then the noise artifact is considered to be substantial and the EMG is considered to have not recruited. An operator may be alerted, based on the substantial nature of the noise artifact. FIG. 12 illustrates a still further manner of performing stimulation artifact rejection according to an alternate embodiment of the present invention. This artifact rejection is premised on the characteristic delay from the stimulation current pulse to the EMG response. For each stimulation current pulse, the time from the current pulse to the first extremum (max or min) is T1 and to the second extremum (max or min) is T2. As will be described below, the values of T1, T2 are each compiled into a histogram period (see FIG. 13). New values of T1, T2 are acquired for each stimulation and the histograms are continuously updated. The value of T1, and T2 used is the center value of the largest bin in the histogram. The values of T1, T2 are continuously updated as the histograms change. Initially Vpp is acquired using a window that contains the entire EMG response. After 20 samples, the use of T1, T2 windows is phased in over a period of 200 samples. Vmax and Vmin are then acquired only during windows centered around T1, T2 with widths of, by way of example only, 5 msec. This method of acquiring Vpp automatically rejects the artifact if T1, or T2 fall outside of their respective windows. Having measured each Vpp EMG response (as facilitated by the stimulation and/or noise artifact rejection techniques described above), this Vpp information is then analyzed relative to the stimulation current in order to determine a relationship between the nerve and the given surgical accessory transmitting the stimulation current. More specifically, the present invention determines these relationships (between nerve and surgical accessory) by identifying the minimum stimulation current (IThresh) capable of resulting in a predetermined Vpp EMG response. According to the present invention, the determination of IThresh may be accomplished via any of a variety of suitable algorithms or techniques. FIGS. 14A-14E illustrate, by way of example only, a threshold-hunting algorithm for quickly finding the threshold current (IThresh) for each nerve being stimulated by a given stimulation current (IStim). Threshold current (IThresh), once again, is the minimum stimulation current (IStim) that results in a Vpp that is greater than a known threshold voltage (VThresh). The value of is adjusted by a bracketing method as follows. The first bracket is 0.2 mA and 0.3 mA. If the Vpp corresponding to both of these stimulation currents is lower than VThresh, then the bracket size is doubled to 0.2 mA and 0.4 mA. This doubling of the bracket size continues until the upper end of the bracket results in a Vpp that is above VThresh. The size of the brackets is then reduced by a bisection method. A current stimulation value at the midpoint of the bracket is used and if this results in a Vpp that is above VThresh, then the lower half becomes the new bracket. Likewise, if the midpoint Vpp is below VThresh then the upper half becomes the new bracket. This bisection method is used until the bracket size has been reduced to IThresh mA. IThresh may be selected as a value falling within the bracket, but is preferably defined as the midpoint of the bracket. The threshold-hunting algorithm of this embodiment will support three states: bracketing, bisection, and monitoring. A stimulation current bracket is a range of stimulation currents that bracket the stimulation current threshold IThresh. The width of a bracket is the upper boundary value minus the lower boundary value. If the stimulation current threshold IThresh of a channel exceeds the maximum stimulation current, that threshold is considered out-of-range. During the bracketing state, threshold hunting will employ the method below to select stimulation currents and identify stimulation current brackets for each EMG channel in range. The method for finding the minimum stimulation current uses the methods of bracketing and bisection. The “root” is identified for a function that has the value −1 for stimulation currents that do not evoke adequate response; the function has the value +1 for stimulation currents that evoke a response. The root occurs when the function jumps from −1 to +1 as stimulation current is increased: the function never has the value of precisely zero. The root will not be known exactly, but only with a level of precision related to the minimum bracket width. The root is found by identifying a range that must contain the root. The upper bound of this range is the lowest stimulation current IThresh where the function returns the value +1, i.e. the minimum stimulation current that evokes response. The lower bound of this range is the highest stimulation current IThresh where the function returns the value −1, i.e. the maximum stimulation current that does not evoke a response. The proximity function begins by adjusting the stimulation current until the root is bracketed (FIG. 14B). The initial bracketing range may be provided in any number of suitable ranges. In one embodiment, the initial bracketing range is 0.2 to 0.3 mA. If the upper stimulation current does not evoke a response, the upper end of the range should be increased. The range scale factor is 2. The stimulation current should preferably not be increased by more than 10 mA in one iteration. The stimulation current should preferably never exceed the programmed maximum stimulation current. For each stimulation, the algorithm will examine the response of each active channel to determine whether it falls within that bracket. Once the stimulation current threshold of each channel has been bracketed, the algorithm transitions to the bisection state. During the bisection state (FIGS. 14C and 14D), threshold hunting will employ the method described below to select stimulation currents and narrow the bracket to a selected width (for example, 0.1 mA) for each EMG channel with an in-range threshold. After the minimum stimulation current has been bracketed (FIG. 14B), the range containing the root is refined until the root is known with a specified accuracy. The bisection method is used to refine the range containing the root. In one embodiment, the root should be found to a precision of 0.1 mA. During the bisection method, the stimulation current at the midpoint of the bracket is used. If the stimulation evokes a response, the bracket shrinks to the lower half of the previous range. If the stimulation fails to evoke a response, the bracket shrinks to the upper half of the previous range. The proximity algorithm is locked on the electrode position when the response threshold is bracketed by stimulation currents separated by the selected width (i.e. 0.1 mA). The process is repeated for each of the active channels until all thresholds are precisely known. At that time, the algorithm enters the monitoring state. During the monitoring state (FIG. 14E), threshold hunting will employ the method described below to select stimulation currents and identify whether stimulation current thresholds are changing. In the monitoring state, the stimulation current level is decremented or incremented by 0.1 mA, depending on the response of a specific channel. If the threshold has not changed then the lower end of the bracket should not evoke a response, while the upper end of the bracket should. If either of these conditions fail, the bracket is adjusted accordingly. The process is repeated for each of the active channels to continue to assure that each threshold is bracketed. If stimulations fail to evoke the expected response three times in a row, then the algorithm may transition back to the bracketing state in order to reestablish the bracket. When it is necessary to determine the stimulation current thresholds (IThresh) for more than one channel, they will be obtained by time-multiplexing the threshold-hunting algorithm as shown in FIG. 15. During the bracketing state, the algorithm will start with a stimulation current bracket of 0.2 mA and increase the size of the bracket. With each bracket, the algorithm will measure the Vpp of all channels to determine which bracket they fall into. After this first pass, the algorithm will determine which bracket contains the IThresh for each channel. Next, during the bisection state, the algorithm will start with the lowest bracket that contains an IThresh and bisect it until IThresh is found within 0.1 mA. If there are more than one IThresh within a bracket, they will be separated out during the bisection process, and the one with the lowest value will be found first. During the monitoring state, the algorithm will monitor the upper and lower boundaries of the brackets for each IThresh, starting with the lowest. If the IThresh for one or more channels is not found in it's bracket, then the algorithm goes back to the bracketing state to re-establish the bracket for those channels. A still further manner of performing multi-channel threshold hunting is described as follows, with reference to FIGS. 14-15. This technique monitors multiple channels but reports the result for a single channel. The user chooses one of two channel selection modes: auto or manual. In the manual channel selection mode, the system will track the stimulation threshold IThresh for a single EMG channel, as shown in FIG. 14. In the auto channel selection mode, the system will monitor responses on a set of channels and track to the lowest responding channel. The auto mode permits the user to select the set of channels to track. Individual channels can be added or subtracted from the set at any time. Tracking to the lowest responding channel is performed in this fashion. First, after stimulation, if no channels in the selected set respond, then the stimulation current is below the lowest responding channel. If any channels respond, then the stimulation current is above the lowest responding channel. Coupling this logic with the bracketing, bisection, and monitoring technique described above allows the system to track to the lowest responding channel, and do so in a quick and accurate fashion. If during monitoring, the tracked channel falls out of the bracket, or if any channel responds at the low end of the bracket, then the bracket will be expanded again, as before, until the lowest responding channel is bracketed again. However, unlike the embodiments shown in FIGS. 14 and 15, the bracket is expanded in situ rather than beginning again from the start. For example, a bracket of 4.5 to 4.6 mA that fails to recruit at both levels is expanded to higher currents. First, the bracket width is doubled from 0.1 mA to 0.2 mA, resulting in stimulation current at 4.7 mA. If this fails to recruit, the bracket is again doubled to 0.4 mA, with stimulation current at 4.9 mA. The pattern continues with stimulations at 5.3, 6.1, and 9.3 mA, corresponding to bracket sizes of 0.8, 1.6, and 3.2 mA, until the threshold is bracketed. If a response is evoked at both ends of the original bracket, the same bracket-doubling technique is used moving toward lower stimulation currents. The reason for doubling the bracket size each time is to identify the threshold current with as few stimulations as practical. The reason for starting the bracket doubling in situ rather than starting over from zero is twofold: (1) to take advantage of threshold information that is already known, and (2) it is more likely that the current threshold has not moved far from where it was previously bracketed. The advantage of tracking only to the lowest channel is that it provides the most relevant nerve proximity information with fewer stimulation pulses than multi-channel detection as with that shown in FIG. 15. This is an advantage because fewer stimulation pulses means a faster responding system, with the goal being to be able to track movement of the stimulation electrode in real time. After identifying the threshold current IThresh, this information may be employed to determine any of a variety of relationships between the surgical accessory and the nerve. For example, as will be described in greater detail below, determining the current threshold IThresh of a nerve while using a surgical access system (such as the sequential dilation system 34 of FIG. 2) may involve determining when (and preferably the degree to which) the surgical accessory comes into close proximity with a given nerve (“nerve proximity”) and/or identifying the relative direction between the surgical accessory and the nerve (“nerve direction”). For a pedicle integrity assessment, the relationship between the pedicle testing assembly 36 and the nerve is whether electrical communication is established therebetween. If electrical communication is established, this indicates that the medial wall of the pedicle has been cracked, stressed, or otherwise breached during the steps of hole formation and/or screw introduction. If not, this indicates that the integrity of the medial wall of the pedicle has remained intact during hole formation and/or screw introduction. This characteristic is based on the insulating properties of bone. For neural pathology assessments according to the present invention, the relationship may be, by way of example only, whether the neurophysiologic response of the nerve has changed over time. Such neurophysiologic responses may include, but are not necessarily limited to, the onset stimulation threshold for the nerve in question, the slope of the response vs. the stimulation signal for the nerve in question and/or the saturation level of the nerve in question. Changes in these parameters will indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery or nerve retraction. In a significant aspect of the present invention, the relationships determined above based on the current threshold determination may be communicated to the user in an easy to use format, including but not limited to, alpha-numeric and/or graphical information regarding mode of operation, nerve proximity, nerve direction, nerve pathology, pedicle integrity assessments, stimulation level, EMG responses, advance or hold instructions, instrument in use, set-up, and related instructions for the user. This advantageously provides the ability to present simplified yet meaningful data to the user, as opposed to the actual EMG waveforms that are displayed to the users in traditional EMG systems. Due to the complexity in interpreting EMG waveforms, such prior art systems typically require an additional person specifically trained in such matters which, in turn, can be disadvantageous in that it translates into extra expense (having yet another highly trained person in attendance) and oftentimes presents scheduling challenges because most hospitals do not retain such personnel. Having described the fundamental aspects of the neurophysiology principles and algorithms of the present invention, various implementations according to the present invention will now be described. I. Surgical Access: Nerve Proximity and Direction FIGS. 2-3 illustrate an exemplary embodiment of the surgical system 20 of the present invention, including the sequential dilation access system 34. The sequential dilation access system 34 of the present invention is capable of accomplishing safe and reproducible access to a surgical target site. It does so by detecting the existence of (and optionally the distance and/or direction to) neural structures before, during, and after the establishment of an operative corridor through (or near) any of a variety of tissues having such neural structures, which, if contacted or impinged, may otherwise result in neural impairment for the patient. The surgical system 20 does so by electrically stimulating nerves via one or more stimulation electrodes at the distal end of the surgical access components 46-50 while monitoring the EMG responses of the muscle groups innervated by the nerves. In one embodiment, the surgical system 20 accomplishes this through the use of the surgical hand-piece 52, which may be electrically coupled to the K-wire 46 via a first cable connector 51a, 51b and to either the dilating cannula 48 or the working cannula 50 via a second cable connector 53a, 53b. For the K-wire 46 and working cannula 50, cables are directly connected between these accessories and the respective cable connectors 51a, 53a for establishing electrical connection to the stimulation electrode(s). In one embodiment, a pincher or clamp-type device 57 is provided to selectively establish electrical communication between the surgical hand-piece 52 and the stimulation electrode(s) on the distal end of the cannula 48. This is accomplished by providing electrical contacts on the inner surface of the opposing arms forming the clamp-type device 57, wherein the contacts are dimensioned to be engaged with electrical contacts (preferably in a male-female engagement scenario) provided on the dilating cannula 48 and working cannula 50. The surgical hand-piece 52 includes one or more buttons such that a user may selectively direct a stimulation current signal from the control unit 22 to the electrode(s) on the distal ends of the surgical access components 46-50. In an important aspect, each surgical access component 46-50 is insulated along its entire length, with the exception of the electrode(s) at their distal end (and, in the case of the dilating cannula 48 and working cannula 50, the electrical contacts at their proximal ends for engagement with the clamp 57). The EMG responses corresponding to such stimulation may be monitored and assessed according to the present invention in order to provide nerve proximity and/or nerve direction information to the user. When employed in spinal procedures, for example, such EMG monitoring would preferably be accomplished by connecting the EMG harness 26 to the myotomes in the patient's legs corresponding to the exiting nerve roots associated with the particular spinal operation level. In a preferred embodiment, this is accomplished via 8 pairs of EMG electrodes 27 placed on the skin over the major muscle groups on the legs (four per side), an anode electrode 29 providing a return path for the stimulation current, and a common electrode 31 providing a ground reference to pre-amplifiers in the patient module 24. Although not shown, it will be appreciated that any of a variety of electrodes can be employed, including but not limited to needle electrodes. The EMG responses measured via the EMG harness 26 provide a quantitative measure of the nerve depolarization caused by the electrical stimulus. By way of example, the placement of EMG electrodes 27 may be undertaken according to the manner shown in Table 1 below for spinal surgery: TABLE 1 Color Channel ID Myotome Spinal Level Blue Right 1 Right Vastus Medialis L2, L3, L4 Violet Right 2 Right TibialisAnterior L4, L5 Grey Right 3 Right Biceps Femoris L5, S1, S2 White Right 4 Right Gastroc. Medial S1, S2 Red Left 1 Left Vastus Medialis L2, L3, L4 Orange Left 2 Left Tibialis Anterior L4, L5 Yellow Left 3 Left Biceps Femoris L5, S1, S2 Green Left 4 Left Gastroc. Medial S1, S2 FIGS. 16-19 illustrate the sequential dilation access system 34 of the present invention in use creating an operative corridor to an intervertebral disk. As shown in FIG. 16, an initial dilating cannula 48 is advanced towards the target site with the K-wire 46 disposed within an inner lumen within the dilating cannula 48. This may be facilitated by first aligning the K-wire 46 and initial dilating cannula 48 using any number of commercially available surgical guide frames. In one embodiment, as best shown in the expanded insets A and B, the K-wire 46 and initial dilating cannula 48 are each equipped with a single stimulation electrode 70 to detect the presence and/or location of nerves in between the skin of the patient and the surgical target site. More specifically, each electrode 70 is positioned at an angle relative to the longitudinal axis of the K-wire 46 and dilator 48 (and working cannula 50). In one embodiment, this angle may range from 5 to 85 degrees from the longitudinal axis of these surgical access components 46-50. By providing each stimulation electrode 70 in this fashion, the stimulation current will be directed angularly from the distal tip of the respective accessory 46, 48. This electrode configuration is advantageous in determining proximity, as well as direction, according to the present invention in that a user may simply rotate the K-wire 46 and/or dilating cannula 48 while stimulating the electrode 70. This may be done continuously or step-wise, and preferably while in a fixed axial position. In either case, the user will be able to determine the location of nerves by viewing the proximity information on the display screen 40 and observing changes as the electrode 70 is rotated. This may be facilitated by placing a reference mark (not shown) on the K-wire 46 and/or dilator 48 (or a control element coupled thereto), indicating the orientation of the electrode 70 to the user. In the embodiment shown, the trajectory of the K-wire 46 and initial dilator 48 is such that they progress towards an intervertebral target site in a postero-lateral, trans-psoas fashion so as to avoid the bony posterior elements of the spinal column. Once the K-wire 46 is docked against the annulus of the particular intervertebral disk, cannulae of increasing diameter may then be guided over the previously installed cannula 48 until a desired lumen diameter is installed, as shown in FIG. 17. By way of example only, the dilating cannulae 26 may range in diameter from 6 mm to 30 mm, with length generally decreasing with increasing diameter size. Depth indicia 72 may be optionally provided along the length of each dilating cannula 48 to aid the user in gauging the depth between the skin of the patient and the surgical target site. As shown in FIG. 18, the working cannula 50 may be slideably advanced over the last dilating cannula 48 after a desired level of tissue dilation has been achieved. As shown in FIG. 19, the last dilating cannula 48 and then all the dilating cannulae 26 may then be removed from inside the inner lumen of the working cannula 50 to establish the operative corridor therethrough. During the advancement of the K-wire 46, each dilating cannula 48, and the working cannula 50, the surgical system 20 will perform (under the direction of a user) the nerve proximity and optionally nerve direction assessments according to the present invention. By way of example, this may be explained with reference to FIGS. 20 and 21, which illustrate exemplary graphic user interface (GUI) screens provided on the screen display 40 for the purpose of allowing the user to control the surgical system 20 to access a surgical target site according to the present invention. In one embodiment, the surgical system 20 initially operates in a “DETECTION” mode, as shown in FIG. 20, wherein a mode label 80 will preferably show the word “DETECTION” highlighted to denote the nerve proximity function of the present invention. A spine image 81 will preferably be provided showing electrode placement on the body, with labeled EMG channel number tabs 82 on each side (1-4 on left and right) capable of being highlighted or colored depending on the specific function being performed. A myotome label 83 is provided indicating the myotome associated with each EMG channel tab 81, including (optionally) the corresponding spinal level(s) associated with the channel of interest. A surgical accessory label 84 is provided indicating the particular surgical accessory 30 being employed at any given time (i.e. “Dilating Cannula” to denote use of the sequential dilation access system 34), as well as a “Dilator in Use” display 85 showing (graphically and numerically) the particular diameter of the dilating cannula 48 in use. A threshold label 86 is also provided indicating the stimulation threshold required to elicit a measurable EMG response for a given myotome. In one embodiment, this is situated, by way of example only, within a cannula graphic 87 denoting a cross-section of the dilating cannula in use). A horizontal bar-chart 88 may also be provided indicating the stimulation level being emitted from the particular surgical accessory in use. Any number of the above-identified indicia (such as the threshold label 86 and EMG channel tabs 82) may be color-coded to indicate general proximity ranges (i.e. “green” for a range of stimulation thresholds above a predetermined safe value, “red” for range of stimulation thresholds below a predetermined unsafe value, and “yellow” for the range of stimulation thresholds in between the predetermined safe and unsafe values—designating caution). In one embodiment, “green” denotes a stimulation threshold range of 9 milliamps (mA) or greater, “yellow” denotes a stimulation threshold range of 6-8 mA, and “red” denotes a stimulation threshold range of 6 mA or below. An “Advance-or-Hold” display 89 may also be provided to aid the user in progressing safely through the tissue required to create the operative corridor. ADVANCE may be highlighted indicating it is safe to advance the cannula (such as where the stimulation threshold is within the safe or “green” range). HOLD may be highlighted indicating to the user that the particular surgical accessory may be too close to a nerve (such as where the stimulation threshold is within the “yellow” or “red” ranges) and/or that the surgical system 20 is in the process of determining proximity and/or direction. In one embodiment, ADVANCE may be omitted, leaving it to the discretion of the user to advance the dilating cannula as soon as the HOLD is no longer illuminated or highlighted. Insertion and advancement of the access instruments 46-50 should be performed at a rate sufficiently slow to allow the surgical system 20 to provide real-time indication of the presence of nerves that may lie in the path of the tip. To facilitate this, the threshold current IThresh may be displayed such that it will indicate when the computation is finished and the data is accurate. For example, when the DETECTION information is up to date and the instrument such that it is now ready to be advanced by the surgeon, it is contemplated to have the color display show up as saturated to communicate this fact to the surgeon. During advancement of the instrument, if an EMG channel's color range changes from green to yellow, advancement should proceed more slowly, with careful observation of the detection level. If the channel color stays yellow or turns green after further advancement, it is a possible indication that the instrument tip has passed, and is moving farther away from the nerve. If after further advancement, however, the channel color turns red, then it is a possible indication that the instrument tip has moved closer to a nerve. At this point the display will show the value of the stimulation current threshold in mA. Further advancement should be attempted only with extreme caution, while observing the threshold values, and only if the clinician deems it safe. If the clinician decides to advance the instrument tip further, an increase in threshold value (e.g. from 3 mA to 4 mA) may indicate the Instrument tip has safely passed the nerve. It may also be an indication that the instrument tip has encountered and is compressing the nerve. The latter may be detected by listening for sporadic outbursts, or “pops”, of nerve activity on a free running EMG audio output forming part of the surgical system 20. Once a nerve is detected using the K-wire 46, dilating cannula 48, or the working cannula 50, the surgeon may select the DIRECTION function to determine the angular direction to the nerve relative to a reference mark on the access components 46-50, as shown in FIG. 21. In one embodiment, a directional arrow 90 is provided, by way of example only, disposed around the cannula graphic 87 for the purpose of graphically indicating to the user what direction the nerve is relative to the access components 46-50. This information helps the surgeon avoid the nerve as he or she advances the cannula. In one embodiment, this directional capability is accomplished by equipping the dilators 48 and working cannula 50 with four (4) stimulation electrodes disposed orthogonally on their distal tip. These electrodes are preferably scanned in a monopolar configuration (that is, using each of the 4 electrodes as the stimulation source). The threshold current (IThresh) is found for each of the electrodes by measuring the muscle evoked potential response Vpp and comparing it to a known threshold Vthresh. From this information, the direction from a stimulation electrode to a nerve may be determined according to the algorithm and technique set forth below and with immediate reference to FIG. 22. The four (4) electrodes are placed on the x and y axes of a two dimensional coordinate system at radius R from the origin. A vector is drawn from the origin along the axis corresponding to each electrode that has a length equal to IThresh for that electrode. The vector from the origin to a direction pointing toward the nerve is then computed. Using the geometry shown, the (x,y) coordinates of the nerve, taken as a single point, can be determined as a function of the distance from the nerve to each of four electrodes. This can be expressly mathematically as follows: Where the “circles” denote the position of the electrode respective to the origin or center of the cannula and the “octagon” denotes the position of a nerve, and d1, d2, d3, and d4 denote the distance between the nerve and electrodes 1-4 respectively, it can be shown that: x = d 1 2 - d 3 2 - 4 R and y = d 2 2 - d 4 2 - 4 R Where R is the cannula radius, standardized to 1, since angles and not absolute values are measured. After conversion from (x,y) to polar coordinates (r,θ), then θ is the angular direction to the nerve. This angular direction may then be displayed to the user, by way of example only, as the arrow 91 shown in FIG. 21 pointing towards the nerve. In this fashion, the surgeon can actively avoid the nerve, thereby increasing patient safety while accessing the surgical target site. The surgeon may select any one of the 4 channels available to perform the Direction Function. The surgeon should preferably not move or rotate the instrument while using the Direction Function, but rather should return to the Detection Function to continue advancing the instrument. After establishing an operative corridor to a surgical target site via the surgical access system 34 of the present invention, any number of suitable instruments and/or implants may be introduced into the surgical target site depending upon the particular type of surgery and surgical need. By way of example only, in spinal applications, any number of implants and/or instruments may be introduced through the working cannula 50, including but not limited to spinal fusion constructs (such as allograft implants, ceramic implants, cages, mesh, etc . . . ), fixation devices (such as pedicle and/or facet screws and related tension bands or rod systems), and any number of motion-preserving devices (including but not limited to total disc replacement systems). II. Pedicle Integrity Assessment With reference again to FIGS. 2-3, the surgical system 20 can also be employed to perform pedicle integrity assessments via the use of pedicle testing assembly 36. More specifically, The pedicle testing assembly 36 of the present invention is used to test the integrity of pedicle holes (after formation) and/or screws (after introduction). The pedicle testing assembly 36 includes a handle assembly 54 and a probe member 56 having a generally ball-tipped end 60. The handle 54 may be equipped with a mechanism (via hardware and/or software) to identify itself to the surgical system 20 when it is attached. In one embodiment, the probe member 56 is disposable and the handle 54 is reusable and sterilizable. The handle 54 may be equipped with one or more buttons for selectively applying the electrical stimulation to the ball-tipped end 60 at the end of the probe member 56. In use, the ball tip 60 of the probe member 56 is placed in the screw hole prior to screw insertion or placed on the installed screw head and then stimulated to initiate the pedicle integrity assessment function of the present invention. As will be explained in greater detail below, it may also applied directly to a nerve to obtain a baseline current threshold level before testing either the screw hole or screw. If the pedicle wall has been breached by the screw or tap or other device employed to form the screw hole, the stimulation current will pass through the bone to the adjacent nerve roots such that they will depolarize at a lower stimulation current. Upon pressing the button on the screw test handle 54, the software will execute a testing algorithm to apply a stimulation current to the particular target (i.e. screw hole, inserted pedicle screw, or bare nerve), setting in motion the pedicle integrity assessment function of the present invention. The pedicle integrity assessment features of the present invention may include, by way of example only, an “Actual” mode (FIGS. 23-24) for displaying the actual stimulation threshold 91 measured for a given myotome, as well as a “Relative” mode (FIGS. 25-27) for displaying the difference 92 between a baseline stimulation threshold assessment 93 of a bare nerve root and an actual stimulation threshold assessment 91 for a given myotome. In either case, the surgical accessory label 84 displays the word “SCREW TEST” to denote use of the pedicle testing assembly 36 for performing pedicle integrity assessments. The screw test algorithm according to the present invention preferably determines the depolarization (threshold) current for all responding EMG channels. In one embodiment, the EMG channel tabs 82 may be configured such that the EMG channel having the lowest stimulation threshold will be automatically enlarged and/or highlighted and/or colored (EMG channel tab R3 as shown in FIG. 23) to clearly indicate this fact to the user. As shown in FIG. 24, this feature may be overridden by manually selecting another EMG channel tab (such as EMG channel tab R1 in FIG. 24) by touching the particular EMG channel tab 82 on the touch screen display 40. In this instance, a warning symbol 94 may be provided next to the EMG channel tab having the lowest stimulation threshold (once again, EMG channel tab R3 in FIG. 23) to inform the user that the stimulation threshold 91 is not the lowest stimulation threshold. Any number of the above-identified indicia (such as the baseline stimulation 93, actual stimulation 91, difference 92, and EMG channel tabs 82) may be color-coded to indicate general safety ranges (i.e. “green” for a range of stimulation thresholds above a predetermined safe value, “red” for range of stimulation thresholds below a predetermined unsafe value, and “yellow” for the range of stimulation thresholds in between the predetermined safe and unsafe values—designating caution). In one embodiment, “green” denotes a stimulation threshold range of 9 milliamps (mA) or greater, “yellow” denotes a stimulation threshold range of 6-8 mA, and “red” denotes a stimulation threshold range of 6 mA or below. By providing this information graphically, a surgeon may quickly and easily test to determine if the integrity of a pedicle has been breached or otherwise compromised, such as may result due to the formation of a pedicle screw hole and/or introduction of a pedicle screw. More specifically, if after stimulating the screw hole and/or pedicle screw itself the stimulation threshold is: (a) at or below 6 mA, the threshold display 40 will illuminate “red” and thus indicate to the surgeon that a breach is likely; (b) between 6 and 8 mA, the threshold display 40 will illuminate “yellow” and thus indicate to the surgeon that a breach is possible; and/or (c) at or above 8 mA, the threshold display 40 will illuminate “green” and thus indicate to the surgeon that a breach is unlikely. If a breach is possible or likely (that is, “yellow” or “red”), the surgeon may choose to withdraw the pedicle screw and redirect it along a different trajectory to ensure the pedicle screw no longer breaches (or comes close to breaching) the medial wall of the pedicle. III. Neural Pathology Monitoring The surgical system 20 may also be employed to perform neural pathology monitoring. As used herein, “neural pathology monitoring” is defined to include monitoring the effect of nerve retraction over time (“nerve retraction monitoring”), as well as monitoring the effect of a surgery on a particular unhealthy nerve (“surgical effect monitoring”). The former—nerve retraction monitoring—is advantageous in that it informs the surgeon if, and the extent to which, such retraction is degrading or damaging an otherwise healthy nerve under retraction. The latter—surgical effect monitoring—is advantageous in that it informs the surgeon if, and the extent to which, the given surgical procedure is improving or aiding a previously unhealthy nerve. In both cases, the qualitative assessment of improvement or degradation of nerve function may be defined, by way of example, based on one or more of the stimulation threshold (IThresh), the slope of the EMG response (uV) versus the corresponding stimulation threshold (IThresh), and/or the saturation or maximum EMG response (Vpp) for a given nerve root being monitored. FIG. 28 illustrates this important aspect of the present invention, noting the differences between a healthy nerve (A) and an unhealthy nerve (B). The inventors have found through experimentation that information regarding nerve pathology (or “health” or “status”) can be extracted from recruitment curves generated according to the present invention. In particular, it has been found that a healthy nerve or nerve bundle will produce a recruitment curve having a generally low current threshold (IThresh), a linear region having a relatively steep slope, and a relatively high saturation region (similar to those shown on recruitment curve “A” in FIG. 28). On the contrary, a nerve or nerve bundle that is unhealthy or whose function is otherwise compromised or impaired (such as being impinged by spinal structures or by prolonged retraction) will produce recruitment curve having a generally higher threshold, a linear region of reduced slope, and a relatively low saturation region (similar to those shown on recruitment curve “B” in FIG. 28). By recognizing these characteristics, one can monitor a nerve root being retracted during a procedure to determine if its pathology or health is affected (i.e. negatively) by such retraction. Moreover, one can monitor a nerve root that has already been deemed pathologic or unhealthy before the procedure (such as may be caused by being impinged by bony structures or a bulging annulus) to determine if its pathology or health is affected (i.e. positively) by the procedure. The nerve root retractor assembly 38 shown in FIG. 2 is capable of performing both types of neural pathology monitoring. However, based on its particular shape and configuration (being bent and suitably shaped to hook and thereafter move a nerve root out of a surgical target site), it is better suited to perform “nerve retraction monitoring.” With combined reference to FIGS. 2 and 29-31, the nerve root retractor assembly 38 includes the same style surgical accessory handle assembly 54 as employed with in the pedicle testing assembly 36. The nerve root retractor 62 has a generally angled orientation relative to the longitudinal axis of the handle assembly 54. The distal end 64 is generally curved and includes an arcuate nerve engagement surface 66 equipped with, by way of example only, two stimulation electrodes 100. As best shown in FIG. 31, the nerve root retractor 62 is preferably removable from the handle assembly 36. To accomplish this, the handle assembly 54 includes a detachable cap member 102. Threads 104 are provided on the proximal end of the nerve root retractor 62 to allow a threaded coupling engagement between the handle assembly 54 and the nerve root retractor 62. During such engagement, electrical contacts 106 on the nerve root retractor 62 becomes electrically coupled to the handle assembly 54 such that, upon activation of one or more of the buttons 108, 110, a stimulation current signal will be transmitted from the control unit 22 and/or patient module 24 and delivered to the stimulation electrodes 100 on the nerve root retractor 62 for the purpose of performing neural pathology monitoring according to the present invention. The nerve root retractor 62 is preferably disposable and, as described above, the handle assembly 54 is reusable and sterilizable. In use, the nerve root retractor 62 is introduced into or near a surgical target site in order to hook and retract a given nerve out of the way. According to the present invention, the nerve root may be stimulated (monopolar or bipolar) before, during, and/or after retraction in order to assess the degree to which such retraction impairs or otherwise degrades nerve function over time. To do so, the user may operate one or more buttons 108, 110 of the handle assembly 54 to selectively transmit a stimulation signal (preferably, a current signal) from the patient module 24 to the electrode(s) on the engagement surface 66 of the nerve root retractor 62. By monitoring the myotome associated with the nerve root being retracted (via the EMG harness 26) and assessing the resulting EMG responses (via the control unit 22), the surgical system 20 can assess whether (and the degree to which) such retraction impairs or adversely affects nerve function over time. With this information, a user may wish to periodically release the nerve root from retraction to allow nerve function to recover, thereby preventing or minimizing the risk of long-term or irreversible nerve impairment. As will be described in greater detail below, a similar neural pathology assessment can be undertaken, whereby an unhealthy nerve may be monitored to determine if nerve function improves due to a particular surgical procedure, such as spinal nerve decompression surgery. The nerve retraction monitoring feature of the present invention is best viewed with regard to FIGS. 32 and 33. The neural pathology screen display 40 may include any of a variety of indicia capable of communicating parameters associated with the nerve retraction monitoring feature of the present invention to a surgeon, including but not limited to (in FIG. 32) a pre-operative recruitment curve graph 120, an intra-operative recruitment curve graph 122, and a differential display 124 indicating the relative difference between the stimulation threshold, slope, and saturation before the surgery and during the surgery. In this manner, the surgeon may intra-operatively assess if the retracted nerve is being damaged or otherwise compromised (such as due to a prolonged surgery), such that it can be temporarily released to allow it to recover before returning to retraction to continue with the surgery. It's believed that releasing the nerve root in this fashion will prevent or reduce the adverse effects (nerve function compromise) that may otherwise result from prolonged retraction. FIG. 33 shows an alternate screen display including a stimulation threshold vs. time graph 130, slope vs. time graph 132, and saturation vs. time graph 134 for a given healthy nerve (as measured at a particular myotome) during nerve retraction monitoring. As will be appreciated, the start of nerve retraction initiates a progressive increase in stimulation threshold 130 and a concomitant progressive decrease in slope 132 and saturation 134, all of which cease and reverse at or close to the point the retraction is stopped. By monitoring this information, a surgeon can effectively determine when the nerve is in need of being released and, after that point, when it is generally safe to resume retraction. The surgical effect nerve monitoring of the present invention is best viewed with regard to FIGS. 34 and 35. The neural pathology screen display 40 may include any of a variety of indicia capable of communicating parameters associated with the surgical effect nerve monitoring feature of the present invention to a surgeon, including but not limited to (in FIG. 34) a pre-operative recruitment curve graph 140, a post-operative recruitment curve graph 142, and a differential display 144 indicating the relative difference between the stimulation threshold, slope, and saturation before the surgery and after the surgery. In this manner, the surgeon may determine whether a previously unhealthy nerve has been positively affected by the surgery. This is particularly advantageous in assessing the effectiveness of spinal decompression surgery, wherein the effectiveness of the decompression may be determined by identifying whether the health of the compressed nerve root improves as a result of the surgery. This determination may also be made, by way of example, by (see FIG. 35) displaying various graphs to the user, such as a stimulation threshold vs. time graph 150, a slope vs. time graph 152, and saturation vs. time graph 154 for a given unhealthy nerve (as measured at a particular myotome) before, during, and after surgery. As can be seen, an improvement in nerve function due to surgery will cause the stimulation threshold to decrease post-operatively and the slope and saturation to increase post-operatively. Although not shown, it is to be readily appreciated that the nerve retraction monitoring and surgical effect nerve monitoring techniques described above (both of which form part of the neural pathology monitoring feature of the present invention), should preferably be performed on different myotomes in that the former technique is particularly suited for assessing a healthy nerve and the latter is particularly suited for assessing an unhealthy nerve. Moreover, although not shown in FIGS. 32-35, the various graphs may be formed based on a compilation of EMG responses from more than one myotome without departing from the scope of the present invention. While this invention has been described in terms of a best mode for achieving this invention's objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the present invention. For example, the present invention may be implemented using any combination of computer programming software, firmware or hardware. As a preparatory step to practicing the invention or constructing an apparatus according to the invention, the computer programming code (whether software or firmware) according to the invention will typically be stored in one or more machine readable storage mediums such as fixed (hard) drives, diskettes, optical disks, magnetic tape, semiconductor memories such as ROMs, PROMs, etc., thereby making an article of manufacture in accordance with the invention. The article of manufacture containing the computer programming code is used by either executing the code directly from the storage device, by copying the code from the storage device into another storage device such as a hard disk, RAM, etc. or by transmitting the code on a network for remote execution. As can be envisioned by one of skill in the art, many different combinations of the above may be used and accordingly the present invention is not limited by the scope of the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>I. Field of the Invention The present invention relates to a system and methods generally aimed at surgery. More particularly, the present invention is directed at a system and related methods for performing surgical procedures and assessments involving the use of neurophysiology. II. Description of Related Art A variety of surgeries involve establishing a working channel to gain access to a surgical target site. Oftentimes, based on the anatomical location of the surgical target site (as well as the approach thereto), the instruments required to form or create or maintain the working channel may have to pass near or close to nerve structures which, if contacted or disturbed, may be problematic to the patient. Examples of such “nerve sensitive” procedures may include, but are not necessarily limited to, spine surgery and prostrate or urology-related surgery. Systems and methods exist for monitoring nerves and nerve muscles. One such system determines when a needle is approaching a nerve. The system applies a current to the needle to evoke a muscular response. The muscular response is visually monitored, typically as a shake or “twitch.” When such a muscular response is observed by the user, the needle is considered to be near the nerve coupled to the responsive muscle. These systems require the user to observe the muscular response (to determine that the needle has approached the nerve). This may be difficult depending on the competing tasks of the user. In addition, when general anesthesia is used during a procedure, muscular response may be suppressed, limiting the ability of a user to detect the response. While generally effective (although crude) in determining nerve proximity, such existing systems are incapable of determining the direction of the nerve to the needle or instrument passing through tissue or passing by the nerves. This can be disadvantageous in that, while the surgeon may appreciate that a nerve is in the general proximity of the instrument, the inability to determine the direction of the nerve relative to the instrument can lead to guess work by the surgeon in advancing the instrument and thereby raise the specter of inadvertent contact with, and possible damage to, the nerve. Another nerve-related issue in existing surgical applications involves the use of nerve retractors. A typical nerve retractor serves to pull or otherwise maintain the nerve outside the area of surgery, thereby protecting the nerve from inadvertent damage or contact by the “active” instrumentation used to perform the actual surgery. While generally advantageous in protecting the nerve, it has been observed that such retraction can cause nerve function to become impaired or otherwise pathologic over time due to the retraction. In certain surgical applications, such as spinal surgery, it is not possible to determine if such retraction is hurting or damaging the retracted nerve until after the surgery (generally referred to as a change in “nerve health” or “nerve status”). There are also no known techniques or systems for assessing whether a given procedure is having a beneficial effect on a nerve or nerve root known to be pathologic (that is, impaired or otherwise unhealthy). In spinal surgery, and specifically in spinal fusion procedures, a still further nerve-related issue exists with regard to assessing the placement of pedicle screws. More specifically, it has been found desirable to detect whether the medial wall of a pedicle has been breached (due to the formation of the hole designed to receive a pedicle screw or due to the placement of the pedicle screw into the hole) while attempting to effect posterior fixation for spinal fusion through the use of pedicle screws. Various attempts have been undertaken at assessing the placement of pedicle screws. X-ray and other imaging systems have been employed, but these are typically quite expensive and are oftentimes limited in terms of resolution (such that pedicle breaches may fail to be detected). Still other attempts involve capitalizing on the insulating characteristics of bone (specifically, that of the medial wall of the pedicle) and the conductivity of the exiting nerve roots themselves. That is, if the medial wall of the pedicle is breached, a stimulation signal (voltage or current) applied to the pedicle screw and/or the pre-formed hole (prior to screw introduction) will cause the various muscle groups coupled to the exiting nerve roots to twitch. If the pedicle wall has not been breached, the insulating nature of the medial wall will prevent the stimulation signal from innervating the given nerve roots such that the muscle groups will not twitch. To overcome this obviously crude technique (relying on visible muscles twitches), it has been proposed to employ electromyographic (EMG) monitoring to assess whether the muscle groups in the leg are innervating in response to the application of a stimulation signal to the pedicle screw and/or the pre-formed hole. This is advantageous in that it detects such evoked muscle action potentials (EMAPs) in the leg muscles as much lower levels than that via the “visual inspection” technique described above. However, the traditional EMG systems employed to date suffer from various drawbacks. First, traditional EMG systems used for pedicle screw testing are typically quite expensive. More importantly, they produce multiple waveforms that must be interpreted by a neurophysiologist. Even though performed by specialists, interpreting such multiple EMG waveforms in this fashion is nonetheless disadvantageously prone to human error and can be disadvantageously time consuming, adding to the duration of the operation and translating into increased health care costs. Even more costly is the fact that the neurophysiologist is required in addition to the actual surgeon performing the spinal operation. The present invention is directed at eliminating, or at least reducing the effects of, the above-described problems with the prior art. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention includes a system and related methods for performing surgical procedures and assessments, including the use of neurophysiology-based monitoring to: (a) determine nerve proximity and nerve direction to surgical instruments employed in accessing a surgical target site; (b) assess the pathology (health or status) of a nerve or nerve root before, during, or after a surgical procedure; and/or (c) assess pedicle integrity before, during or after pedicle screw placement, all in an automated, easy to use, and easy to interpret fashion so as to provide a surgeon-driven system. The present invention accomplishes this by combining neurophysiology monitoring with any of a variety of instruments used in or in preparation for surgery (referred to herein as “surgical accessories”). By way of example only, such surgical accessories may include, but are not necessarily limited to, any number of devices or components for creating an operative corridor to a surgical target site (such as K-wires, sequentially dilating cannula systems, distractor systems, and/or retractor systems), devices or components for assessing pedicle integrity (such as a pedicle testing probe), and/or devices or components for retracting or otherwise protecting a nerve root before, during and/or after surgery (such as a nerve root retractor). Although described herein largely in terms of use in spinal surgery, it is to be readily appreciated that the teachings of the method and apparatus of the present invention are suitable for use in any number of additional surgical procedures wherein tissue having significant neural structures must be passed through (or near) in order to establish an operative corridor to a surgical target site, wherein neural structures are located adjacent bony structures, and/or wherein neural structures are retracted or otherwise contacted during surgery. The fundamental method steps according to the present invention include: (a) stimulating one or more electrodes provided on a surgical accessory; (b) measuring the response of nerves innervated by the stimulation of step (a); (c) determining a relationship between the surgical accessory and the nerve based upon the response measured in step (b); and communicating this relationship to the surgeon in an easy-to-interpret fashion. The step of stimulating may be accomplished by applying any of a variety of suitable stimulation signals to the electrode(s) on the surgical accessory, including voltage and/or current pulses of varying magnitude and/or frequency. The stimulating step may be performed at different times depending upon the particular surgical accessory in question. For example, when employed with a surgical access system, stimulation may be performed during and/or after the process of creating an operative corridor to the surgical target site. When used for pedicle integrity assessments, stimulation may be performed before, during and/or after the formation of the hole established to receive a pedicle screw, as well as before, during and/or after the pedicle screw is introduced into the hole. With regard to neural pathology monitoring, stimulation may be performed before, during and/or after retraction of the nerve root. The step of measuring the response of nerves innervated by the stimulation step may be performed in any number of suitable fashions, including but not limited to the use of evoked muscle action potential (EMAP) monitoring techniques (that is, measuring the EMG responses of muscle groups associated with a particular nerve). According to one aspect of the present invention, the measuring step is preferably accomplished via monitoring or measuring the EMG responses of the muscles innervated by the nerve(s) stimulated in step for each of the preferred functions of the present invention: surgical access, pedicle integrity assessments, and neural pathology monitoring. The step of determining a relationship between the surgical accessory and the nerve based upon the measurement step may be performed in any number of suitable fashions depending upon the manner of measuring the response, and may define the relationship in any of a variety of fashions (based on any number of suitable parameters and/or characteristics). By way of example only, the step of determining a relationship, within the context of a surgical access system, may involve identifying when (and preferably the degree to which) the surgical accessory comes into close proximity with a given nerve (“nerve proximity”) and/or identifying the relative direction between the surgical accessory and the nerve (“nerve direction”). For a pedicle integrity assessment, the relationship between the surgical accessory (screw test probe) and the nerve is whether electrical communication is established therebetween. If electrical communication is established, this indicates that the medial wall of the pedicle has been cracked, stressed, or otherwise breached during the steps of hole formation and/or screw introduction. If not, this indicates that the integrity of the medial wall of the pedicle has remained intact during hole formation and/or screw introduction. This characteristic is based on the insulating properties of bone. For neural pathology assessments according to the present invention, the relationship may be, by way of example only, whether the neurophysiologic response of the nerve has changed over time. Such neurophysiologic responses may include, but are not necessarily limited to, the onset stimulation threshold for the nerve in question, the slope of the response vs. the stimulation signal for the nerve in question and/or the saturation level of the nerve in question. Changes in these parameters will indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery. The step of communicating this relationship to the surgeon in an easy-to-interpret fashion may be accomplished in any number of suitable fashions, including but not limited to the use of visual indicia (such as alpha-numeric characters, light-emitting elements, and/or graphics) and audio communications (such as a speaker element). By way of example only, with regard to surgical access systems, this step of communicating the relationship may include, but is not necessarily limited to, visually representing the stimulation threshold of the nerve (indicating relative distance or proximity to the nerve), providing color coded graphics to indicate general proximity ranges (i.e. “green” for a range of stimulation thresholds above a predetermined safe value, “red” for range of stimulation thresholds below a predetermined unsafe value, and “yellow” for the range of stimulation thresholds in between the predetermined safe and unsafe values—designating caution), as well as providing an arrow or other suitable symbol for designating the relative direction to the nerve. This is an important feature of the present invention in that, by providing such proximity and direction information, a user will be kept informed as to whether a nerve is too close to a given surgical accessory element during and/or after the operative corridor is established to the surgical target site. This is particularly advantageous during the process of accessing the surgical target site in that it allows the user to actively avoid nerves and redirect the surgical access components to successfully create the operative corridor without impinging or otherwise compromising the nerves. Based on these nerve proximity and direction features, then, the present invention is capable of passing through virtually any tissue with minimal (if any) risk of impinging or otherwise damaging associated neural structures within the tissue, thereby making the present invention suitable for a wide variety of surgical applications. With regard to pedicle integrity assessments, the step of communicating the relationship may include, but is not necessarily limited to, visually representing the actual stimulation threshold of an exiting nerve root alone or in combination with the stimulation threshold of a bare nerve root (with or without the difference therebetween), as well as with providing color coded graphics to indicate general ranges of pedicle integrity (i.e. “green” for a range of stimulation thresholds above a predetermined safe value—indicating “breach unlikely”, “red” for range of stimulation thresholds below a predetermined unsafe value—indicating “breach likely”, and “yellow” for the range of stimulation thresholds between the predetermined safe and unsafe values—indicating “possible breach”). This is a significant feature, and advantage over the prior art, in that it provides a straightforward and easy to interpret representation as to whether a pedicle has been breached during and/or after the process of forming the hole and/or introducing the pedicle screw. Identifying such a potential breach is helpful in that it prevents or minimizes the chance that a misplaced pedicle screw (that is, one breaching the medial wall) will be missed until after the surgery. Instead, any such misplaced pedicle screws, when stimulated according to the present invention, will produce an EMG response at a myotome level associated with the nerve in close proximity to the pedicle screw that is breaching the pedicle wall. This will indicate to the surgeon that the pedicle screw needs to be repositioned. But for this system and technique, patients may be released and subsequently experience pain due to the contact between the exiting nerve root and the pedicle screw, which oftentimes requires another costly and painful surgery. As for neural pathology monitoring, the step of communicating the relationship may include, but is not necessarily limited to, visually representing the changes over time in the onset stimulation threshold of the nerve, the slope of the response versus the stimulation threshold of the nerve and/or the saturation level of the nerve. Once again, these changes may indicate if the health or status of the nerve is improving or deteriorating, such as may result during surgery and/or retraction. This feature is important in that it may provide qualitative feedback on the effect of the particular surgery. If it appears the health or status (pathology) of the nerve is deteriorating over time, the user may be instructed to stop or lessen the degree of retraction to avoid such deterioration. If the pathology of the nerve improves over time, it may indicate the success of the surgery in restoring or improving nerve function, such as may be the case in decompressive spinal surgery. The present invention also encompasses a variety of techniques, algorithms, and systems for accomplishing the steps of (a) stimulating one or more electrodes provided on a surgical accessory; (b) measuring the response of nerves innervated by the stimulation of step (a); (c) determining a relationship between the surgical accessory and the nerve based upon the response measured in step (b); and/or communicating this relationship to the surgeon in an easy-to-interpret fashion. | 20040325 | 20090421 | 20050407 | 74324.0 | 1 | FOREMAN, JONATHAN M | SYSTEM AND METHODS FOR PERFORMING SURGICAL PROCEDURES AND ASSESSMENTS | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,809,518 | ACCEPTED | Indicator circuit arrangement of a transmission cable for computer | An indicator circuit arrangement of a transmission cable for connecting a peripheral apparatus to a computer is disclosed to have a cord-like electroluminescent lamp axially extended in the cable between the electric connectors at the ends of the cable, and a detector and converter circuit installed in one electric connector and adapted to detect the connection status of the cable between the computer and the peripheral apparatus and to drive on the cord-like electroluminescent lamp upon normal connection of the cable between the computer and the peripheral apparatus. | 1. An indicator circuit arrangement installed in a transmission cable comprising a cable, two electric connectors respectively connected to two distal ends of said cable for connecting a peripheral apparatus to a computer for signal transmission, and a plurality of indicator lights respectively installed in said electric connectors, the indicator circuit arrangement comprising a cord-like electroluminescent lamp installed in said cable and axially extended between said two electric connectors, and a detector converter circuit mounted in one said electric connector and electrically connected to said cord-like electroluminescent lamp and the indicator lights of said electric connector and adapted to detect electric connection of said electric connectors between the computer and the peripheral apparatus and to drive on/off said cord-like electroluminescent lamp and the indicator lights of said electric connector subject to the connection status of said electric connectors between the computer and the peripheral apparatus. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission cable for computer and more particularly, to the indicator circuit arrangement of a transmission cable for computer, which uses a detector converter circuit to detect the connection status of the cable and to drive on a cord-like electroluminescent lamp in the cable. 2. Description of the Related Art FIG. 1 illustrates a transmission cable for computer according to the prior art. According to this design, the transmission cable 10 comprises a cable 12 and two electric connectors 11, 11′ at the ends of the cable 12. The transmission cable 10 can be a USB (universal serial bus) design or IEEE1394 parallel bus design. The electric connectors 11, 11′ each have a LED (light emitting diode) mounted on the inside. One electric connector 11 or 11′ has a detecting circuit (not shown) provided on the inside. The detecting circuit detects connection and signal transmission status of the transmission cable 10, and controls the operation of the LEDs of the electric connectors 11, 11′ subject to detection result. This design of transmission cable is functional, however it is still not satisfactory in use. Because the electric connectors 11, 11′ are respectively connected to the computer and the peripheral apparatus, the computer and the peripheral apparatus may keep the light of the LEDs of the electric connectors 11, 11′ from sight. Further, when several transmission cables are arranged together, the user cannot quickly inspect the connection status of one specific transmission cable from a group of transmission cables. SUMMARY OF THE INVENTION The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide an indicator circuit arrangement of a transmission cable for computer, which gives off light through the length of the cable to indicate normal connection of the cable between the computer and the peripheral apparatus. It is another object of the present invention to provide an indicator circuit arrangement of a transmission cable for computer, which gives off a particular color of light upon normal connection of the cable between the computer and the peripheral apparatus for quick identification. To achieve these and other objects of the present invention, the indicator circuit arrangement is installed in a transmission cable, which comprises a cable, two electric connectors respectively connected to two distal ends of the cable for connecting a peripheral apparatus to a computer for signal transmission, and a plurality of indicator lights respectively installed in the electric connectors. The indicator circuit arrangement comprises a cord-like electroluminescent lamp installed in the cable and axially extended between the two electric connectors, and a detector converter circuit mounted in one electric connector and electrically connected to the cord-like electroluminescent lamp and the indicator lights of the electric connectors and adapted to detect electric connection of the electric connectors between the computer and the peripheral apparatus and to drive on/off the cord-like electroluminescent lamp and the indicator lights subject to the connection status of the electric connectors between the computer and the peripheral apparatus. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic drawing of a transmission cable for compute according to the prior art. FIG. 2 is a cutaway view showing an indicator circuit arrangement installed in a transmission cable according to the present invention. FIG. 3 illustrates the outer appearance of the transmission cable shown in FIG. 2. FIG. 4 is a partial view of the transmission cable showing another structure of electric connector at the other end of the cable according to the present invention. FIG. 5 is a schematic drawing showing a status of use of the transmission cable according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 2˜5, a transmission cable 20 is shown for connecting a peripheral apparatus to a computer. The transmission cable 20 can be a universal serial bus or IEEE1394 parallel bus design, comprising a cable 22, two electric connectors 21, 21′ respectively connected to the two distal ends of the cable 22, a cord-like electroluminescent lamp 26 axially mounted in the cable 22 and electrically connected between the electric connectors 21, 21′. The cable 22 has an electrically insulative transparent outer shell. The electric connectors 21, 21′ each have an indicator light (lighting emitting diode) 24 installed therein. Further, a detector converter circuit 25 is installed in the housing 23 or 23′ of one electric connector 21 or 21′. The detector converter circuit 25 is adapted to detect normal connection of the transmission cable between the computer and the peripheral apparatus and to convert DC to AC, i.e., to convert 5V obtained from the computer into the desired working voltage for driving the cord-like electroluminescent lamp 26. The detector converter circuit 25 turns on the cord-like electroluminescent lamp 26 and the LEDs 24 in the electric connectors 21, 21′ (see FIG. 5) after normal connection of the transmission cable 20 between the computer and the peripheral apparatus, and drives the cord-like electroluminescent lamp 26 and the LEDs 24 to flash upon transmission of a signal between the computer and the peripheral apparatus through the cable 22. On the contrary, disconnection of the transmission cable 20 between the computer and the peripheral apparatus causes the detector converter circuit 25 to turn off the cord-like electroluminescent lamp 26 and the LEDs 24. Further, the cord-like electroluminescent lamp 26 can be made to produce a particular color of light. By means of the control of the detector converter circuit 25, the cord-like electroluminescent lamp 26 is automatically turned on to emit cold light upon connection of the transmission cable 20 between the computer and the peripheral apparatus, and driven to flash upon transmission of a signal between the computer and the peripheral apparatus through the transmission cable 20. Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a transmission cable for computer and more particularly, to the indicator circuit arrangement of a transmission cable for computer, which uses a detector converter circuit to detect the connection status of the cable and to drive on a cord-like electroluminescent lamp in the cable. 2. Description of the Related Art FIG. 1 illustrates a transmission cable for computer according to the prior art. According to this design, the transmission cable 10 comprises a cable 12 and two electric connectors 11 , 11 ′ at the ends of the cable 12 . The transmission cable 10 can be a USB (universal serial bus) design or IEEE1394 parallel bus design. The electric connectors 11 , 11 ′ each have a LED (light emitting diode) mounted on the inside. One electric connector 11 or 11 ′ has a detecting circuit (not shown) provided on the inside. The detecting circuit detects connection and signal transmission status of the transmission cable 10 , and controls the operation of the LEDs of the electric connectors 11 , 11 ′ subject to detection result. This design of transmission cable is functional, however it is still not satisfactory in use. Because the electric connectors 11 , 11 ′ are respectively connected to the computer and the peripheral apparatus, the computer and the peripheral apparatus may keep the light of the LEDs of the electric connectors 11 , 11 ′ from sight. Further, when several transmission cables are arranged together, the user cannot quickly inspect the connection status of one specific transmission cable from a group of transmission cables. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide an indicator circuit arrangement of a transmission cable for computer, which gives off light through the length of the cable to indicate normal connection of the cable between the computer and the peripheral apparatus. It is another object of the present invention to provide an indicator circuit arrangement of a transmission cable for computer, which gives off a particular color of light upon normal connection of the cable between the computer and the peripheral apparatus for quick identification. To achieve these and other objects of the present invention, the indicator circuit arrangement is installed in a transmission cable, which comprises a cable, two electric connectors respectively connected to two distal ends of the cable for connecting a peripheral apparatus to a computer for signal transmission, and a plurality of indicator lights respectively installed in the electric connectors. The indicator circuit arrangement comprises a cord-like electroluminescent lamp installed in the cable and axially extended between the two electric connectors, and a detector converter circuit mounted in one electric connector and electrically connected to the cord-like electroluminescent lamp and the indicator lights of the electric connectors and adapted to detect electric connection of the electric connectors between the computer and the peripheral apparatus and to drive on/off the cord-like electroluminescent lamp and the indicator lights subject to the connection status of the electric connectors between the computer and the peripheral apparatus. | 20040326 | 20051227 | 20050929 | 97498.0 | 0 | LE, THANH TAM T | INDICATOR CIRCUIT ARRANGEMENT OF A TRANSMISSION CABLE FOR COMPUTER | SMALL | 0 | ACCEPTED | 2,004 |
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10,809,538 | ACCEPTED | Interference and noise estimation in an OFDM system | Noise and interference can be independently measured in a multiple user Orthogonal Frequency Division Multiplexing (OFDM) system. Co-channel interference is measured in a frequency hopping, multiple user, OFDM system by tracking the sub-carriers assigned to all users in a particular service area or cell. The composite noise plus interference can be determined by measuring the amount of received power in a sub-carrier whenever it is not assigned to any user in the cell. A value is stored for each sub-carrier in the system and the value of noise plus interference can be a weighted average of the present value with previously stored values. The noise component can be independently determined in a synchronous system. In the synchronous system, all users in a system may periodically be prohibited from broadcasting over a sub-carrier and the received power in the sub-carrier measured during the period having no broadcasts. | 1. A method of estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising: receiving OFDM symbols; and detecting a received power of a signal in an unassigned sub-carrier frequency band. 2. The method of claim 1, further comprising averaging the received power with at least one previously stored received power measurement for the unassigned sub-carrier frequency band. 3. The method of claim 1, further comprising, prior to detecting the received power, demodulating an unassigned sub-carrier corresponding to the unassigned sub-carrier frequency band. 4. The method of claim 1, further comprising determining the unassigned sub-carrier frequency band based in part on a received message. 5. The method of claim 1, further comprising determining the unassigned sub-carrier frequency band based in part on an internally generated sequence. 6. The method of claim 1, wherein receiving OFDM symbols comprises wirelessly receiving, from a base station transmitter, RF OFDM symbols. 7. The method of claim 1, wherein receiving OFDM symbols comprises: converting wirelessly received RF OFDM symbols to baseband OFDM symbols; removing a guard interval from the baseband OFDM symbols; and transforming, using a Fast Fourier Transform (FFT), time domain OFDM baseband signals to modulated sub-carriers. 8. The method of claim 1, wherein detecting the received power comprises determining one of a magnitude, an amplitude, or a squared magnitude of the signal in the unassigned OFDM frequency band. 9. The method of claim 1, wherein detecting the received power comprises determining a sum of a square of a quadrature signal component with a square of an in-phase signal component. 10. The method of claim 1, further comprising: determining if the unassigned sub-carrier frequency band comprises a system wide unassigned sub-carrier frequency band; storing the detected received power as a noise plus interference estimate if the sub-carrier frequency band does not comprise the system wide unassigned frequency band; and storing the detected received power as a noise floor estimate if the sub-carrier frequency band comprises the system wide unassigned frequency band. 11. The method of claim 10, further comprising synchronizing a time reference with a transmitter transmitting the OFDM symbols. 12. The method of claim 1, further comprising: averaging the received power with at least one previously stored received power measurement to produce a noise estimate corresponding to the unassigned sub-carrier frequency band; and communicating the noise estimate to a transmitter. 13. The method of claim 12, wherein communicating the noise estimate to the transmitter comprises transmitting the noise estimate from a terminal transmitter to a base transceiver station. 14. A method of estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising: receiving OFDM symbols in a wireless cellular communication system, the OFDM symbols corresponding to a symbol period; determining an unassigned sub-carrier during the symbol period; determining a power, during the symbol period, of a signal in a frequency band corresponding to the unassigned sub-carrier; storing a value of the power of the signal in a memory; and averaging the power of the signal with previously stored values to generate a noise estimate. 15. An apparatus for estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system, the apparatus comprising: a wireless receiver configured to wirelessly receive OFDM symbols corresponding to an OFDM symbol period; a detector configured to detect a received power level of signals received by the wireless receiver during the OFDM symbol period; a processor coupled to the detector and configured to determine an unassigned sub-carrier during the OFDM symbol period and determine a noise estimate based in part on a received power level in a frequency band corresponding to the unassigned sub-carrier. 16. The apparatus of claim 15, further comprising a memory coupled to the processor, the processor storing the noise estimate in the memory. 17. The apparatus of claim 15, further comprising a memory coupled to the processor and storing a predetermined number of previously determined noise estimates corresponding to the unassigned sub-carrier, the processor determining an average noise estimate based in part on the noise estimate and the previously determined noise estimates. 18. The apparatus of claim 15, wherein the wireless receiver comprises: an RF receiver portion configured to wirelessly receive RF OFDM symbols and convert the RF OFDM symbols to the OFDM symbols; a Fast Fourier Transform (FFT) module configured to receive the OFDM symbols from the RF receiver portion and transform the OFDM symbols to modulated sub-carriers; and a demodulator coupled to the FFT module and configured to demodulate the modulated sub-carriers. 19. The apparatus of claim 18, wherein the detector detects the received power levels of an output of the demodulator. 20. The apparatus of claim 15, wherein the detector detects the received power level by determining one of a magnitude, an amplitude, or a squared magnitude of the signals received by the wireless receiver during the OFDM symbol period. | CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Patent Application Ser. No. 60/470,724, filed May 14, 2003, which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the field of wireless communications. More particularly, the invention relates to systems and methods for estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system. 2. Description of the Related Art Wireless communication systems are continually relied upon to transmit enormous amounts of data in a variety of operating conditions. The amount of frequency spectrum, or bandwidth, that is allocated to a communication system is often limited by government regulations. Thus, there is a constant need to optimize data throughput in a given communication bandwidth. The problem of optimizing data throughput in a given communication band is compounded by the need to simultaneously support multiple users. The users may each have different communication needs. One user may be transmitting low rate signals, such as voice signals, while another user may be transmitting high rate data signals, such as video. A communication system can implement a particular method of efficiently utilizing a communication band to support multiple users. Wireless communication systems can be implemented in many different ways. For example, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), and Orthogonal Frequency Division Multiplexing (OFDM) are used in wireless communication systems. Each of the different communication systems has advantages and disadvantages related to particular system aspects. FIG. 1 is a frequency-time representation of signals in a typical OFDM system. The OFDM system has an allocated frequency spectrum 120. The allocated frequency spectrum 120 is divided into multiple carriers, for example 130a-130d and 132a-132d. The multiple carriers in an OFDM system may also be referred to as sub-carriers. Each of the sub-carriers, for example 130a, is modulated with a low rate data stream. Additionally, as the system name implies, each of the sub-carriers, for example 130a, is orthogonal to all of the other sub-carriers, for example 130b-130d and 132a-132d. The sub-carriers, for example 130a-130d, can be constructed to be orthogonal to one another by gating the sub-carrier on and off. A sub-carrier, for example 130a, gated on and off using a rectangular window produces a frequency spectrum having a (sin (x))/x shape. The rectangular gating period and the frequency spacing of the sub-carriers, for example 130a and 130b, can be chosen such that the spectrum of the modulated first sub-carrier 130a is nulled at the center frequencies of the other sub-carriers, for example 130b-130d. The OFDM system can be configured to support multiple users by allocating a portion of the sub-carriers to each user. For example, a first user may be allocated a first set of sub-carriers 130a-130d and a second user may be allocated a second set of sub-carriers 132a-132d. The number of sub-carriers allocated to users need not be the same and the sub-carriers do not need to be in a contiguous band. Thus, in the time domain, a number of OFDM symbols 110a-110n are transmitted, resulting in a frequency spectrum of orthogonal sub-carriers 130a-130d and 132a-132d. Each of the sub-carriers, for example 130a, is independently modulated. One or more sub-carriers 130a-130d may be allocated to an individual communication link. Additionally, the number of sub-carriers assigned to a particular user may change over time. Thus, OFDM is a promising multiplexing technique for high data rate transmission over wireless channels that can be implemented in wireless communication systems, such as cellular communication systems supporting large numbers of users. However, cellular systems use a frequency reuse concept to enhance the efficiency of spectral utilization. Frequency reuse introduces co-channel interference (CCI), which is a major source of performance degradation in such systems. As discussed above, all users within the same cell or sector of an OFDM system are orthogonal to each other because all of the sub-carriers are orthogonal. Thus, within the same cell or sector, the multiple sub-carriers cause substantially no interference to each other. However, adjacent cells or sectors may use the same frequency space because of frequency reuse. Hence, in an OFDM system, users in different cells or sectors are sources of interference and produce the main source of CCI for adjacent cells or sectors. It is desirable to be able to determine the level of CCI in an OFDM wireless communication receiver. The level of CCI is needed at the receiver for two main reasons. The receiver may operate in a closed power control loop with a transmitter and needs to know the level of CCI to adjust the power level transmitted on each sub-carrier in order to maintain the signal to interference plus noise ratio (SNIR) required for a certain performance. The receiver also needs an estimate of CCI for Carrier to Interference (C/I) or SINR values that are used in the operation of a channel decoder. SUMMARY OF THE INVENTION A method and apparatus for determining a noise estimate in an OFDM system are disclosed. An estimate of the noise can be determined by detecting the received power in an unassigned sub-carrier frequency band. If the unassigned sub-carrier frequency band corresponds to a locally unassigned sub-carrier, the received power represents an estimate of the noise plus interference in the sub-carrier frequency band. If the unassigned sub-carrier frequency band corresponds to a system wide unassigned sub-carrier, the received power represents an estimate of the noise floor in the sub-carrier frequency band. In one aspect, the invention is a method of determining a noise estimate comprising receiving OFDM symbols and detecting a received power in an unassigned sub-carrier frequency band. In another aspect, the invention is a method of determining a noise estimate comprising receiving OFDM symbols in a wireless cellular communication system, where the symbols correspond to a symbol period. The method includes determining unassigned sub-carriers during the symbol period and determining a received power of signals in the unassigned sub-carrier frequency bands. The power is stored in memory and averaged with previously stored values to generate a noise estimate. In another aspect, the invention is an apparatus for estimating noise in an OFDM system. The apparatus includes a receiver configured to wirelessly receive OFDM symbols and a detector configured to detect the received power level of signals received by the receiver. A processor is included in the apparatus to determine unassigned sub-carriers in a symbol period and to determine a noise estimate based at least in part one the received power levels. BRIEF DESCRIPTION OF THE DRAWINGS The above-described aspects and other aspects, features and advantages of the invention will be apparent upon review of the following detailed description and the accompanying drawings. In the drawings, like reference characters identify identical or functionally equivalent elements. FIG. 1 is a functional frequency-time representation of a typical OFDM system. FIG. 2 is a functional block diagram of an OFDM system implemented in a cellular environment. FIG. 3 is a functional block diagram of an OFDM transmitter. FIGS. 4A-4B are functional block diagrams of OFDM receivers. FIG. 5 is a spectrum diagram of a portion of an OFDM frequency band. FIG. 6 is a flowchart of a method of determining noise and interference in an OFDM system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A functional block diagram of a cellular OFDM wireless communication system 200 having receivers that incorporate sub-carrier noise and interference detection is shown in FIG. 2. The OFDM system 200 includes a number of base stations 210a-210g that provide communication for a number of terminals 220a-220o. A base station, for example 210a, can be a fixed station used for communicating with the terminals, for example 220a, and may also be referred to as an access point, a Node B, or some other terminology. Various terminals 220a-220o may be dispersed throughout the OFDM system 200, and each terminal may be fixed, for example 220k, or mobile, for example 220b. A terminal, for example 220a may also be referred to as a mobile station, a remote station, a user equipment (UE), an access terminal, or some other terminology. Each terminal, for example 220a, may communicate with one or possibly multiple base stations on the downlink and/or uplink at any given moment. Each terminal, for example 220m, may include an OFDM transmitter 300m and an OFDM receiver 400m to enable communications with the one or more base stations. Embodiments of the OFDM transmitter 300m and the OFDM receiver 400m are described in further detail in FIGS. 3 and 4. In FIG. 2, terminals 220a through 220o can receive, for example pilot, signaling, and user-specific data transmissions from base stations 210a through 210g. Each base station, for example 210a, in the OFDM system 200 provides coverage for a particular geographic area, for example 202a. The coverage area of each base station is typically dependent on various factors (e.g., terrain, obstructions, and so on) but, for simplicity, is often represented by an ideal hexagon as shown in FIG. 2. A base station and/or its coverage area are also often referred to as a “cell”, depending on the context in which the term is used. To increase capacity, the coverage area of each base station, for example 210a, may be partitioned into multiple sectors. If each cell is partitioned into three sectors, then each sector of a sectorized cell is often represented by an ideal 120° wedge that represents one third of the cell. Each sector may be served by a corresponding base transceiver subsystem (BTS), for example 212d. The BTS 212d includes an OFDM transmitter 300d and an OFDM receiver 400d, each of which are described in greater detail in FIGS. 3 and 4. For a sectorized cell, the base station for that cell often includes all of the BTSs that serve the sectors of that cell. The term “sector” is also often used to refer to a BTS and/or its coverage area, depending on the context in which the term is used. As will be discussed in further detail below, each base station, for example 210a, typically implements a transmitter configured to provide the downlink, also referred to as the forward link, communication to terminals, for example 520a. Additionally, each base station, for example 210a, also implements a receiver configured to receive the uplink, also referred to as reverse link, communication from the terminals, for example 520a. In the downlink direction, the base station transmitter receives a signal from a signal source, which may be a Public Switched Telephone Network (PSTN) or some other signal source. The base station transmitter then converts the signal to an OFDM signal that is to be transmitted to one or more terminals. The base station transmitter may digitize the signal, multiplex the signal into several parallel signals, and modulate a predetermined number of sub-carriers corresponding to the number of parallel signal paths. The number of sub-carriers may be constant or may change. Additionally, the sub-carriers may be adjacent to one another so as to define a contiguous frequency band or may be disjoint from one another so as to occupy a number of independent frequency bands. The base station may assign sub-carriers in a method that is constant, such as in the case of a fixed number of sub-carriers, pseudo-random, or random. The base station transmitter may also include an analog or Radio Frequency (RF) portion to convert OFDM baseband signals to a desired transmit frequency band. In an OFDM system 200, frequency reuse may occur in every cell. That is, the up link an down link frequencies used by a first base station, for example 210d, in a first cell, for example 202d, may be used by the base stations, 210a-c and 210e-g, in adjacent cells 202a-c and 202e-g. As described above, each base station transmitter contributes to the co-channel interference (CCI) experienced by neighboring receivers, in this case neighboring terminal receivers. For example, the transmitter in a first base station 210f contributes to the CCI of terminals, 220e and 220g, in adjacent cells 202c and 202d, that are not communicating with the first base station 210f. To help minimize the amount of CCI experienced by neighboring terminals, the base station transmitter can be part of a closed loop power control system. To help minimize the amount of CCI experienced by terminals outside of a cell, for example 202f, the base station transmitter may minimize the RF power it transmits to each of the terminals, 220m and 220l, with which the base station 210f is in communication. The base station transmitter can adjust the transmit power based in part on a determination of the noise level in each sub-carrier band and on a power control signal transmitted by the terminal and received by a base station receiver. The base station, for example 210b, can attempt to maintain a predetermined SINR or C/I value for each sub-carrier, such that a predetermined quality of service is maintained to the terminals, for example 220b-d. An SIR or C/I that is greater than the predetermined value may contribute little to the quality of service seen by the terminal, for example 520b, but would result in an increased CCI for all adjacent cells, 202a, 202d, and 202e. Conversely, an SINR or C/I value that is below the predetermined level can result in greatly decreased quality of service experienced by the terminal, 220b. The base station receiver can measure the noise and interference levels in each of the sub-carrier bands as part of a power control loop that sets a SINR or C/I of the transmit signal. The base station receiver measures the noise and interference levels in each of the sub-carrier bands and stores the levels. As sub-carriers are assigned to communication links, the base station transmitter examines the noise and interference levels in determining the power to allocate to each sub-carrier. Thus, the base station transmitter can maintain a predetermined SINR or C/I for each sub-carrier that minimizes the CCI experienced by terminals in other cells. In another embodiment, the terminal, for example 220i, can attempt to maintain the minimum received SINR or C/I required for achieving a predetermined quality of service. When the received SINR or C/I is above a predetermined level, the terminal 220i can transmit a signal to the base station 210f to request the base station 210f reduce the transmit signal power. Alternatively, if the received SINR or C/I is below the predetermined level, the terminal 220i can transmit a signal to the base station 210f to request that the base station 210f increase the transmit signal power. Thus, by minimizing the power transmitted to any given terminal, the amount of CCI experienced by terminals in adjacent cells is minimized. FIG. 3 is a functional block diagram of an OFDM transmitter 300 that may be incorporated, for example in a base transceiver station or a terminal. The functional block diagram of the OFDM transmitter 300 includes the baseband section details the baseband portion of the transmitter and does not show signal processing, source interface, or RF sections that may be included in the transmitter 300. The OFDM transmitter 300 includes one or more sources 302 that correspond to one or more data streams. When the OFDM transmitter 300 is a base station transmitter, the sources 302 may include data streams from an external network, such as a PSTN network. Each of the data streams may be intended for a separate terminal. The data provided by the sources 302 can be multiple parallel data streams, serial data streams, multiplexed data streams, or a combination of data streams. The sources 302 provides the data to a modulator 310. The modulator 310 processes and modulates the input sources. The modulator 310 can include functional blocks that perform interleaving, encoding, grouping, and modulation, as is known in the art. The modulator 310 is not limited to performing a particular type of interleaving. For example, the modulator can independently block interleave the source data for each terminal. The modulator 310 can also be configured to perform encoding. Again, the transmitter 300 is not limited to a particular type of encoding. For example, the modulator 310 may perform Reed-Solomon encoding or convolutional encoding. The encoding rate may be fixed or may vary depending on the number of sub-carriers assigned to a communication link to the terminal. For example, the modulator 310 can perform convolutional encoding with a rate one half encoder when a first number of sub-carriers are assigned to a terminal and can be controlled to perform convolutional encoding with a rate of one third when a second number of sub-carriers are assigned to the terminal. In another example, the modulator can perform Reed-Solomon encoding with a rate that varies depending on the number of sub-carriers assigned to the terminal. The modulator 310 also can be configured to modulate the data using a predetermined format. For example, the modulator 310 can perform Quadrature Amplitude Modulation (QAM), Quadrature Phase Shift Keying (QPSK), Binary Phase Shift Keying (BPSK), or some other modulation format. In another embodiment, the modulator 310 processes the data into a format for modulating the sub-carriers. The modulator 310 can also include amplifiers or gain stages to adjust the amplitude of the data symbols assigned to the sub-carriers. The modulator 310 may adjust the gain of the amplifiers on a sub-carrier basis, with the gain to each sub-carrier dependent, at least in part, on the noise and interference in the sub-carrier bandwidth. The output of the modulator 310 is coupled to the input of a 1:N multiplexer 320, where N represents the maximum number of sub-carriers used in the transmit link of the communication system. The multiplexer 320 may also be referred to as a “serial to parallel converter” because the multiplexer 320 receives serial data from the modulator 310 and converts it to a parallel format to interface with the plurality of sub-carriers. A sub-carrier assignment module 312 controls the modulator 310 and the multiplexer 320. The number of sub-carriers used to support the source data can be, and typically is, less than the maximum number of sub-carriers used in the transmit link of the communication system. The number of sub-carriers assigned to a particular communication link can change over time. Additionally, even if the number of sub-carriers assigned to a particular communication link remains the same, the identity of the sub-carriers can change over time. Sub-carriers can be randomly, or pseudo-randomly, assigned to communication links. Because the identity of the sub-carriers can change, the frequency bands occupied by the communication link can change over time. The communication system can be a frequency hopping system implementing a predetermined frequency hopping method. The sub-carrier assignment module 312 can implement the frequency hopping method and can track the set of sub-carriers used and the sets of sub-carriers allocated to communication links. For example, in a base station with three forward link signals, the sub-carrier assignment module 312 may assign a first set of sub-carriers to a first communication link, a second set of sub-carriers to a second communication link, and a third set of sub-carriers to a third communication link. The number of sub-carriers in each set may be the same of may be different. The sub-carrier assignment module 312 tracks the number of sub-carriers allocated to communication links and the number of sub-carriers that are idle and capable of assignment to communication links. The sub-carrier assignment module 312 controls the modulator 310 to provide the desired encoding, and modulation required supporting the assigned sub-carrier set. Additionally, the sub-carrier assignment module 312 controls the multiplexer 320 such that data from the modulator 310 is provided to the multiplexer channel corresponding to an assigned sub-carrier. Thus, the sub-carrier assignment module 312 controls the identity of and number of sub-carriers assigned to a particular communication link. The sub-carrier assignment module 312 also tracks the identity of sub-carriers that are idle and that can be allocated to a communication link. The output of the multiplexer 320 is coupled to an Inverse Fast Fourier Transform (IFFT) module 330. A parallel bus 322 having a width equal to or greater than the total number sub-carriers couples the parallel output from the multiplexer 320 to the IFFT module 330. A Fourier transform performs a mapping from the time domain to the frequency domain. Thus, an inverse Fourier transform performs a mapping from the frequency domain to the time domain. The IFFT module 330 transforms the modulated sub-carriers into a time domain signal. Fourier transform properties ensure that the sub-carrier signals are evenly spaced and are orthogonal to one another. The parallel output from the IFFT module 330 is coupled to a demultiplexer 340 using another parallel bus 332. The demultiplexer 340 converts the parallel modulated data stream into a serial stream. The output of the demultiplexer 340 may then be coupled to a guard band generator (not shown) and then to a Digital to Analog Converter (DAC) (not shown). The guard band generator inserts a period of time between successive OFDM symbols to minimize effects of inter-symbol interference due to multipath in the communication link. The output of the DAC may then be coupled to an RF transmitter (not shown) that upconverts the OFDM signal to a desired transmit frequency band. FIGS. 4A-4B are functional block diagrams of OFDM receiver 400 embodiments. The OFDM receiver 400 can be implemented in the base station or in a terminal, such as a mobile terminal. The OFDM receiver 400 of FIG. 4A implements a noise estimator primarily in the digital domain, while the OFDM receiver 400 of FIG. 4B implements a noise estimator primarily in the analog domain. The OFDM receiver 400 of FIG. 4A receives at an antenna 402 RF signals that are transmitted by a complementary OFDM transmitter. The output of the antenna 420 is coupled to a receiver 410 that can filter, amplify, and downconvert to baseband the received OFDM signal. The baseband output from the receiver 410 is coupled to a guard removal module 420 that is configured to remove the guard interval inserted between OFDM symbols at the transmitter. The output of the guard removal module 420 is coupled to an Analog to Digital Converter (ADC) 422 that converts the analog baseband signal to a digital representation. The output of the ADC 422 is coupled to a multiplexer 424 that transforms the serial baseband signal into N parallel data paths. The number N represents the total number of OFDM sub-carriers. The symbols in each of the parallel data paths represent the gated time domain symbols of the OFDM signal. The parallel data paths are coupled to an input of a Fast Fourier Transform (FFT) module 430. The FFT module 430 transforms the gated time domain signals into frequency domain signals. Each of the outputs from the FFT module 430 represents a modulated sub-carrier. The parallel output from the FFT module 430 is coupled to a demodulator 440 that demodulates the OFDM sub-carriers. The demodulator 440 may be configured to demodulate only a subset of the sub-carriers received by the receiver 400 or may be configured to demodulate all of the outputs from the FFT module 430, corresponding to all of the sub-carriers. The demodulator 440 output can be a single symbol or can be a plurality of symbols. For example, if the sub-carrier is quadrature modulated, the demodulator 440 can output in-phase and quadrature signal components of the demodulated symbol. The output of the demodulator 440 is coupled to a detector 450. The detector 450 is configured to detect the received power in each of the sub-carrier frequency bands. The detector 450 can detect the received power by detecting or other wise determining, for example, a power, an amplitude, a magnitude squared, a magnitude, and the like, or some other representation of the demodulated sub-carrier signal that correlates with received power. For example, a magnitude squared of a quadrature modulated signal can be determined by summing the squares of the in-phase and quadrature signal components. The detector 450 can include a plurality of detectors or can include a single detector that determines the detected value of desired sub-carrier signals prior to the occurrence of the next demodulated symbol. A processor 460 interfaces with memory 470 that includes processor readable instructions. The memory 470 can also includes rewriteable storage locations that are used to store and update the detected sub-carrier noise values. The sub-carriers allocated to a particular communication link may change at each symbol boundary. A frequency hopping sequence or frequency hopping information that identifies the sub-carriers allocated to the communication link to the receiver 400 can also be stored in memory 470. The processor 460 uses the frequency hopping information to optimize performance of the FFT module 430, the demodulator 440, and the detector 450. Thus, the processor 460 is able to use the frequency hopping sequence, or other frequency hopping information, to identify which of the sub-carriers are allocated to a communication link and which of the sub-carriers are idle. For example, where less than the total number of sub-carriers is allocated to the communication link to the receiver 400, the processor 460 can control the FFT module 430 to determine only those FFT output signals that correspond to the allocated sub-carriers. In another embodiment, the processor 460 controls the FFT module 430 to determine the output signals corresponding to the sub-carriers allocated to the communication link to the receiver 400 plus the outputs corresponding to sub-carriers that are idle and not allocated to any communication link. The processor 460 is able to relieve some of the load on the FFT module 430 by decreasing the number of FFT output signals it needs to determine. The processor 460 may also control the demodulator 440 to only demodulate those signals for which the FFT module 430 provides an output signal. Additionally, the processor 460 may control the detector 450 to detect only those sub-carrier signals that correspond to idle, or unallocated sub-carriers. Because the detector 450 can be limited to detecting noise levels in unallocated sub-carriers, the detector 450 can be configured to detect the signals prior to the demodulator. However, placing the detector 450 after the demodulator 440 may be advantageous because the noise detected by the detector 450 will have experienced the same signal processing experienced by symbols in that sub-carrier. Thus, the statistical properties of the signal processing experienced by the demodulated noise will be similar to the statistical properties experienced by the demodulated symbols. The processor 460 can track the noise in the sub-carriers by detecting the power of the demodulated noise in a sub-carrier whenever the sub-carrier is not assigned to a communication link. The detected power of the unassigned sub-carrier represents the power of interference plus noise in that sub-carrier band. The processor can store the detected power in a memory location in memory 470 corresponding to the sub-carrier. In a frequency hopping OFDM system, the identity of unassigned sub-carriers changes over time, and may change at each symbol boundary. The processor 460 can store a number of detected power measurements for a first sub-carrier in independent memory locations. The processor 460 can then average a predetermined number of detected power measurements. Alternatively, the processor 460 can compute a weighted average of the noise and interference by weighting each of the stored detected power measurements by a factor that depends, in part, on the age of the detected power measurement. In still another embodiment, the processor 460 can store the detected noise and interference power in a corresponding location in memory 470. The processor 460 may then update the noise and interference value for a particular sub-carrier by weighting the stored value by a first amount and weighting a new detected power by as second amount and storing the sum in the memory location corresponding to the sub-carrier. Using this alternative update method, only N storage locations are required to store the N sub-carrier noise and interference estimates. It may be seen that other methods of storing and updating the noise and interference values for the sub-carriers are available. The detected power for an unassigned sub-carrier represents the aggregate noise and interference for that sub-carrier band unless no interfering sources are broadcasting in the frequency band. When no interfering sources are broadcasting in the sub-carrier frequency band, the detected power represents the detected power of the noise floor. An OFDM system may guarantee that no system sources are broadcasting an interfering signal in a sub-carrier band by synchronizing all transmitters and defining a period during which all of the transmitters do not transmit over a particular sub-carrier. That is, where the noise estimator is performed in a receiver at the terminal, all base stations in an OFDM system may periodically stop transmitting on one or more predetermined sub-carrier frequencies during a predetermined symbol period. Communication in the OFDM system does not cease during the period in which the single sub-carrier is unassigned because all other sub-carriers may continue to be allocated to communication links. Thus, the level of noise without interference may be determined for each of the sub-carrier frequency bands by synchronizing the transmitters and periodically not assigning each of the sub-carriers to any communication link for one or more symbol periods. Then, the noise power with no interfering sources can be determined for the sub-carrier band during the period of non-assignment. FIG. 4B is a functional block diagram of another embodiment of an OFDM receiver 400 in which the noise and interference are detected using analog devices. The receiver 400 initially receives OFDM signals at an antenna 402 and couples the output of the antenna 402 to a receiver 410. As in the previous embodiment, the receiver 410 filters, amplifies, and downconverts to baseband the received OFDM signal. The output of the receiver 410 is coupled to the input of a filter 480. The baseband output of the receiver 410 may also be coupled to other signal processing stages (not shown), such as a guard removal module, a FFT module, and a demodulator. In one embodiment, the filter 480 is a filter bank having a number of baseband filters equal to a number of sub-carriers in the communication system. Each of the filters can be configured to have substantially the same bandwidth as the signal bandwidth of the sub-carrier. In another embodiment, the filter 480 is a filter bank having one or more tunable filters that can be tuned to any sub-carrier band in the communication system. The tunable filters are tuned to the sub-carrier frequency bands that are not allocated to the communication link to the receiver 400. The bandwidth of the tunable filters can be substantially the same as the bandwidth of the sub-carrier band. The output from the filter 480 is coupled to the detector 490. The output from the filter 480 may be one or more filtered signals. The number of output signals from the filter 480 may be as high as the number of sub-carriers in the communication system. The detector 490 can be configured to detect the power in each of the filtered signals. The detector 490 can include one or more power detectors. The power detectors can correspond to an output of the filter 480. Alternatively, one or more power detectors can be used to successively detect the power from each of the filter outputs. The output of the detector 490 is coupled to the input of an ADC 494. The ADC 494 can include a plurality of converters, each corresponding to a one of the detector 490 outputs. Alternatively, the ADC 494 can include a single ADC that is sequentially converts each of the detector 490 outputs. A processor 460 interfacing with a memory 470 can be coupled to the output of the ADC 494. The processor 460 can be configured, using processor readable instructions stored in memory 470, to control the ADC 494 to convert only those detected power levels of interest. Additionally, the processor 460 can track the frequency hopping sequence and update the detected noise and interference levels as in the previous embodiment. The noise level can be detected independent of the interference level in synchronous systems where all transmitters can be controlled to periodically cease transmitting on a predetermined sub-carrier for a predetermined duration, such as a symbol period. FIG. 5 is a spectrum diagram of a portion of an OFDM frequency band 500 during a predetermined period of time. The OFDM frequency band 500 includes a number of sub-carriers that each occupy a predetermined frequency band, for example 502a. A plurality of communication links may simultaneously occupy the OFDM frequency band 500. The plurality of communication links may use only a subset of the total number of sub-carriers available in the system. For example, a first communication link may be allocated four sub-carriers occupying four frequency bands, 502a-d. The sub-carriers and the corresponding frequency bands 502a-d are shown as positioned in one contiguous frequency band. However, the sub-carriers allocated to a particular communication link do not need to be adjacent and may be any of the available sub-carriers in the OFDM system. A second communication link may be allocated a second set of sub-carriers, and thus a second set of sub-carrier frequency bands 522a-d. Similarly a third and a fourth communication link may be allocated a third set and a fourth set, respectively, of sub-carriers. The third set of sub-carriers corresponds to a third set of frequency bands 542a-c and the fourth set of sub-carriers corresponds to a fourth set of sub-carrier frequency bands 562a-c. The number of sub-carriers allocated to a particular communication link may vary with time and may vary according to the loads placed on the communication link. Thus, higher data rate communication links may be allocated a higher number of sub-carriers. The number of sub-carriers allocated to a communication link may change at each symbol boundary. Thus, the number and position of sub-carriers allocated in the OFDM system may change at each symbol boundary. Because the total number of allocated sub-carriers may not correspond to the total number of sub-carriers available in the OFDM system, there may be one or more sub-carriers that are not allocated to any communication link, and thus are idle. For example, three sub-carrier bands, 510a-c, 530a-c, and 550a-e, are shown in the OFDM frequency band 500 as not allocated to any communication link. Again, the unassigned sub-carriers, and thus the corresponding sub-carrier bands, need not be adjacent and do not necessarily occur between allocated sub-carriers. For example, some or all of the unassigned sub-carriers may occur at one end of the frequency band. A receiver can estimate, and update estimates of, the noise plus interference in a sub-carrier by detecting the power in the sub-carrier band when the sub-carrier is unassigned. An unassigned sub-carrier can represent a sub-carrier that is locally unassigned, such as in a cell or sector in which the receiver is positioned. Other cells or sectors of a cell may allocate the sub-carrier to a communication link. For example, a first receiver, such as a receiver in a terminal may establish a communication link with a base station using a first set of sub-carriers in a first frequency band 502a-d. The first receiver can estimate the noise and interference in an unassigned frequency band, for example 530a, by determining the power in the sub-carrier frequency band 530a. As discussed earlier, the receiver may update an estimate previously stored in memory by averaging previously stored power levels with the most recently measured power level. Alternatively, the most recently determined power level, corresponding to the most recent noise and interference estimate, may be used in the determination of a weighted average of a predetermined number of recent noise plus interference estimates. Additionally, in a synchronized system, one or more of the sub-carriers may be unassigned for all transmitters for a predetermined duration, for example one symbol duration. Thus, the sub-carrier is unassigned in all cells of a particular OFDM system for the symbol duration. Then for the system wide unassigned sub-carrier the receiver can estimate the noise floor by determining the power in the sub-carrier frequency band, for example 550d, during the period in which no transmitter is transmitting in the frequency band. The receiver may also update the noise estimates by averaging or weighted averaging a number of estimates. The receiver may separately store the estimate of the noise floor for each of the sub-carrier bands. Thus, the receiver is periodically able to update the noise floor and noise and interference levels in each of the sub-carrier bands. FIG. 6 is a flowchart of a method 600 of determining and updating noise and interference levels in OFDM sub-carrier bands. The method 600 may be implemented in a receiver in an OFDM system. The receiver can be, for example, the receiver in a terminal. Alternatively, or additionally, the receiver can be, for example, a receiver in a base station transceiver. The method 600 begins at block 602 where the receiver synchronizes in time with the transmitter. The receiver may, for example, synchronize a time reference with a time reference in the transmitter. The receiver may need to synchronize with the transmitter for a variety of reasons unrelated to noise estimation. For example, the receiver may need to synchronize with the transmitter in order to determine which sub-carriers are allocated to its communication link during one or more symbol periods. The receiver next proceeds to block 610 where the receiver determines the unused, or unassigned, sub-carriers in the next symbol period. The transmitter may send this information to the receiver in an overhead message. Thus, a message received by the receiver indicates which of the sub-carriers are unassigned in a given symbol period. Alternatively, the assignment of sub-carriers may be pseudo random and the receiver may have synchronized a locally generated pseudo random sequence with the transmitter in the previous synchronization step. In the alternative embodiment, the receiver determines the unassigned sub-carriers based on an internally generated sequence, such as the locally generated pseudo random sequence or an internally generated frequency hopping sequence. The receiver proceeds to block 620 where the transmitted OFDM signals are received. The received symbols may include those assigned sub-carriers allocated to the communication link with the receiver as well as sub-carriers not allocated to the communication link with the receiver. The receiver proceeds to block 622 where the receiver converts the received signals to a baseband OFDM signal. The received signals are typically wirelessly transmitted to the receiver as RF OFDM symbols using an RF link. The receiver typically converts the received signal to a baseband signal to facilitate signal processing. After converting the received signal to a baseband signal, the receiver proceeds to block 624 where the guard intervals are removed from the received signals. As discussed earlier in the discussion of the OFDM transmitter, the guard intervals are inserted to provide multipath immunity. After removal of the guard intervals, the receiver proceeds to block 630 where the signal is digitized in an ADC. After digitizing the signal, the receiver proceeds to block 632 where the signal is converted from a serial signal to a number of parallel signals. The number of parallel signals may be as high as, and is typically equal to, the number of sub-carriers in the OFDM system. After the serial to parallel conversion, the receiver proceeds to block 640 where the receiver performs an FFT on the parallel data. The FFT transforms the time domain OFDM signals into modulated sub-carriers in the frequency domain. The receiver proceeds to block 650 where at least some of the modulated sub-carriers output from the FFT are demodulated. The receiver typically demodulates the sub-carriers allocated to the communication link with the receiver and also demodulates the unassigned sub-carriers. The receiver then proceeds to block 660 where the unassigned sub-carriers are detected to provide a noise and interference estimate. If the sub-carrier is a system wide unassigned sub-carrier, the detected output represents an estimate of the noise floor for that sub-carrier band. The receiver then proceeds to block 670 and updates the noise plus interference and noise floor estimates stored in memory. As discussed earlier, the receiver may store a predetermined number of most recently determined noise plus interference estimates and perform an average of the estimates. Similarly, the receiver may determine an average of a predetermined number of recently determined noise floor estimates. The receiver proceeds to block 680 where the noise estimate is communicated to a transmitter. For example, if the receiver is a terminal receiver, the terminal receiver may communicate the noise estimate to a transmitter in a base station transceiver. The terminal receiver may first communicate the noise estimate to an associated terminal transmitter. The terminal transmitter may then transmit the noise estimate to the base station receiver. The base station receiver, in turn communicates the noise estimate to the base station transmitter. The base station transmitter may use the noise estimate to adjust the power level transmitted by the transmitter at the sub-carrier corresponding to the noise estimate. The base station receiver may similarly communicate the received noise estimate to a terminal transmitter by first transmitting the noise estimate, using the base station transmitter, to the terminal receiver. At block 690, the receiver determines a signal quality of subsequently received symbols based in part on the noise estimate determined using the unassigned sub-carrier. For example, the receiver estimates the noise plus interference of an unassigned sub-carrier. At the next symbol period, the receiver may receive a symbol over the same, previously unassigned, sub-carrier. The receiver is then able to determine a signal quality, such as C/I or SINR, based in part on the previously determined noise estimate. Similarly, where the receiver determines a noise floor estimate, the receiver is able to determine a SNR for subsequent symbols received on the same sub-carrier. Because the number and position of unassigned sub-carriers typically vary randomly, or pseudo randomly, the receiver is able to periodically update the estimates of noise plus interference and noise floor for each of the sub-carrier frequency bands in the OFDM system. A receiver is thus able to generate and update estimates of noise plus interference and noise floor that can be communicated to transmitter stages in an effort to minimize CCI. Electrical connections, couplings, and connections have been described with respect to various devices or elements. The connections and couplings may be direct or indirect. A connection between a first and second device may be a direct connection or may be an indirect connection. An indirect connection may include interposed elements that may process the signals from the first device to the second device. Those of skill in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof. Those of skill will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled persons may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The invention relates to the field of wireless communications. More particularly, the invention relates to systems and methods for estimating noise in an Orthogonal Frequency Division Multiplexing (OFDM) system. 2. Description of the Related Art Wireless communication systems are continually relied upon to transmit enormous amounts of data in a variety of operating conditions. The amount of frequency spectrum, or bandwidth, that is allocated to a communication system is often limited by government regulations. Thus, there is a constant need to optimize data throughput in a given communication bandwidth. The problem of optimizing data throughput in a given communication band is compounded by the need to simultaneously support multiple users. The users may each have different communication needs. One user may be transmitting low rate signals, such as voice signals, while another user may be transmitting high rate data signals, such as video. A communication system can implement a particular method of efficiently utilizing a communication band to support multiple users. Wireless communication systems can be implemented in many different ways. For example, Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), and Orthogonal Frequency Division Multiplexing (OFDM) are used in wireless communication systems. Each of the different communication systems has advantages and disadvantages related to particular system aspects. FIG. 1 is a frequency-time representation of signals in a typical OFDM system. The OFDM system has an allocated frequency spectrum 120 . The allocated frequency spectrum 120 is divided into multiple carriers, for example 130 a - 130 d and 132 a - 132 d. The multiple carriers in an OFDM system may also be referred to as sub-carriers. Each of the sub-carriers, for example 130 a, is modulated with a low rate data stream. Additionally, as the system name implies, each of the sub-carriers, for example 130 a, is orthogonal to all of the other sub-carriers, for example 130 b - 130 d and 132 a - 132 d. The sub-carriers, for example 130 a - 130 d, can be constructed to be orthogonal to one another by gating the sub-carrier on and off. A sub-carrier, for example 130 a, gated on and off using a rectangular window produces a frequency spectrum having a (sin (x))/x shape. The rectangular gating period and the frequency spacing of the sub-carriers, for example 130 a and 130 b, can be chosen such that the spectrum of the modulated first sub-carrier 130 a is nulled at the center frequencies of the other sub-carriers, for example 130 b - 130 d. The OFDM system can be configured to support multiple users by allocating a portion of the sub-carriers to each user. For example, a first user may be allocated a first set of sub-carriers 130 a - 130 d and a second user may be allocated a second set of sub-carriers 132 a - 132 d. The number of sub-carriers allocated to users need not be the same and the sub-carriers do not need to be in a contiguous band. Thus, in the time domain, a number of OFDM symbols 110 a - 110 n are transmitted, resulting in a frequency spectrum of orthogonal sub-carriers 130 a - 130 d and 132 a - 132 d. Each of the sub-carriers, for example 130 a, is independently modulated. One or more sub-carriers 130 a - 130 d may be allocated to an individual communication link. Additionally, the number of sub-carriers assigned to a particular user may change over time. Thus, OFDM is a promising multiplexing technique for high data rate transmission over wireless channels that can be implemented in wireless communication systems, such as cellular communication systems supporting large numbers of users. However, cellular systems use a frequency reuse concept to enhance the efficiency of spectral utilization. Frequency reuse introduces co-channel interference (CCI), which is a major source of performance degradation in such systems. As discussed above, all users within the same cell or sector of an OFDM system are orthogonal to each other because all of the sub-carriers are orthogonal. Thus, within the same cell or sector, the multiple sub-carriers cause substantially no interference to each other. However, adjacent cells or sectors may use the same frequency space because of frequency reuse. Hence, in an OFDM system, users in different cells or sectors are sources of interference and produce the main source of CCI for adjacent cells or sectors. It is desirable to be able to determine the level of CCI in an OFDM wireless communication receiver. The level of CCI is needed at the receiver for two main reasons. The receiver may operate in a closed power control loop with a transmitter and needs to know the level of CCI to adjust the power level transmitted on each sub-carrier in order to maintain the signal to interference plus noise ratio (SNIR) required for a certain performance. The receiver also needs an estimate of CCI for Carrier to Interference (C/I) or SINR values that are used in the operation of a channel decoder. | <SOH> SUMMARY OF THE INVENTION <EOH>A method and apparatus for determining a noise estimate in an OFDM system are disclosed. An estimate of the noise can be determined by detecting the received power in an unassigned sub-carrier frequency band. If the unassigned sub-carrier frequency band corresponds to a locally unassigned sub-carrier, the received power represents an estimate of the noise plus interference in the sub-carrier frequency band. If the unassigned sub-carrier frequency band corresponds to a system wide unassigned sub-carrier, the received power represents an estimate of the noise floor in the sub-carrier frequency band. In one aspect, the invention is a method of determining a noise estimate comprising receiving OFDM symbols and detecting a received power in an unassigned sub-carrier frequency band. In another aspect, the invention is a method of determining a noise estimate comprising receiving OFDM symbols in a wireless cellular communication system, where the symbols correspond to a symbol period. The method includes determining unassigned sub-carriers during the symbol period and determining a received power of signals in the unassigned sub-carrier frequency bands. The power is stored in memory and averaged with previously stored values to generate a noise estimate. In another aspect, the invention is an apparatus for estimating noise in an OFDM system. The apparatus includes a receiver configured to wirelessly receive OFDM symbols and a detector configured to detect the received power level of signals received by the receiver. A processor is included in the apparatus to determine unassigned sub-carriers in a symbol period and to determine a noise estimate based at least in part one the received power levels. | 20040324 | 20130702 | 20050106 | 94685.0 | 0 | PATEL, CHANDRAHAS B | INTERFERENCE AND NOISE ESTIMATION IN AN OFDM SYSTEM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,809,674 | ACCEPTED | Method and apparatus for preventing loading and execution of rogue operating systems in a logical partitioned data processing system | A method, apparatus, and computer instructions for managing operating systems. A request from an operating system is received in the multi-partitioned data processing system to register for access to hardware in the multi-partitioned data processing system. The request includes a key code for the operating system. A determination is made as to whether the operating system is an authorized operating system using the key code in response to receiving the request. The operating system is registered if the operating system is the authorized operating system. Otherwise, the operating system is terminated. | 1. A method in a multi-partitioned data processing system for managing operating systems, the method comprising: receiving a request from an operating system in the multi-partitioned data processing system to register for access to hardware in the multi-partitioned data processing system, wherein the request includes a key code for the operating system; responsive to receiving the request, determining whether the operating system is an authorized operating system using the key code; and registering the operating system if the operating system is the authorized operating system. 2. The method of claim 1 further comprising: terminating the operating system if the operating system is an-unauthorized operating system. 3. The method of claim 1, wherein the determining step includes: comparing the key code to a set of key codes for authorized operating systems; and determining whether a match is present between the key code and any key code in the set of key codes. 4. The method of claim 3, wherein the set of key codes is located in a partition profile. 5. The method of claim 3, wherein the set of key codes are defined through a hardware management console. 6. The method of claim 4, wherein the partition profile is stored in a nonvolatile memory. 7. The method of claim 1, wherein the key code for the operating system is embedded within the operating system and is a unique key code. 8. The method of claim 1, wherein the receiving step, the determining step, and the registering step are performed in platform firmware. 9. The method of claim 1 further comprising: responsive to receiving a call to access hardware, determining whether the operating system is registered; responsive to receiving the call to access the hardware, determining whether the call is necessary to setup the operating system; and terminating the operating system if the operating system is not registered and if the call if unnecessary to setup the operating system. 10. A data processing system for managing operating systems, the data processing system comprising: receiving means for receiving a request from an operating system in the multi-partitioned data processing system to register for access to hardware in the multi-partitioned data processing system, wherein the request includes a key code for the operating system; determining means, responsive to receiving the request, for determining whether the operating system is an authorized operating system using the key code; and registering means for registering the operating system if the operating system is the authorized operating system. 11. The data processing system of claim 10 further comprising: terminating means for terminating the operating system if the operating system is an unauthorized operating system. 12. The data processing system of claim 10, wherein the determining step includes: comparing means for comparing the key code to a set of key codes for authorized operating systems; and means for determining whether a match is present between the key code and any key code in the set of key codes. 13. The data processing system of claim 12, wherein the set of key codes is located in a partition profile. 14. The data processing system of claim 12, wherein the set of key codes are defined through a hardware management console. 15. The data processing system of claim 13, wherein the partition profile is stored in a nonvolatile memory. 16. The data processing system of claim 10, wherein the key code for the operating system is embedded within the operating system and is a unique key code. 17. The data processing system of claim 10, wherein the receiving means, the determining step, and the registering step are performed in platform firmware. 18. The data processing system of claim 10, wherein determining means is the first determining means and further comprising: second determining means, responsive to receiving a call to access hardware, for determining whether the operating system is registered; third determining means, responsive to receiving the call to access the hardware, for determining whether the call is necessary to setup the operating system; and terminating means for terminating the operating system if the operating system is not registered and if the call if unnecessary to setup the operating system. 19. A computer program product in a computer readable medium for managing operating systems, the computer program product comprising: first instructions for receiving a request from an operating system in the multi-partitioned data processing system to register for access to hardware in the multi-partitioned data processing system, wherein the request includes a key code for the operating system; second instructions, responsive to receiving the request, for determining whether the operating system is an authorized operating system using the key code; and third instructions for registering the operating system if the operating system is the authorized operating system. 20. The computer program product of claim 19 further comprising: fourth instructions for terminating the operating system if the operating system is an unauthorized operating system. 21. The computer program product of claim 19, wherein the second instructions includes: first sub-instructions for comparing the key code to a set of key codes for authorized operating systems; and second sub-instructions for determining whether a match is present between the key code and any key code in the set of key codes. 22. The computer program product of claim 21, wherein the set of key codes is located in a partition profile. 23. The computer program product of claim 21, wherein the set of key codes are defined through a hardware management console. 24. The computer program product of claim 22, wherein the partition profile is stored in a nonvolatile memory. 25. The computer program product of claim 19, wherein the key code for the operating system is embedded within the operating system and is a unique key code. 26. The computer program product of claim 19, wherein the first instructions, the determining step, and the registering step are performed in platform firmware. 27. The computer program product of claim 19 further comprising: fourth instructions, responsive to receiving a call to access hardware, for,determining whether the operating system is registered; fifth instructions, responsive to receiving the call to access the hardware, for determining whether the call is necessary to setup the operating system; and sixth instructions for terminating the operating system if the operating system is not registered and if the call if unnecessary to setup the operating system. | BACKGROUND OF THE INVENTION 1. Technical Field The present invention relates generally to an improved data processing system and in particular to a method, apparatus, and computer instructions for processing data. Still more particularly, the present invention relates to a method, apparatus, and computer instructions for managing operating systems in a logical partitioned data processing system. 2. Description of Related Art Increasingly large symmetric multi-processor data processing systems, such as IBM eServer P690, available from International Business Machines Corporation, DHP9000 Superdome Enterprise Server, available from Hewlett-Packard Company, and the Sunfire 15K server, available from Sun Microsystems, Inc. are not being used as single large data processing systems. Instead, these types of data processing systems are being partitioned and used as smaller systems. These systems are configured as multi-partition enabled systems. In other words, a single physical data processing system has multiple partitions in which each partition has an operating system. These partitions may execute concurrently. When the partitions are made in a logical manner, these systems are also referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platforms resources. These platform allocatable resources include one or more architecturally distinct processors with their interrupt management area, regions of system memory, and input/output (I/O) adapter bus Blots. The partition's resources are represented by the platform's firmware to the operating system image. Each distinct operation system or image of an operating system running within a platform is protected from each other such that software errors on one logical partition cannot affect the correct operations of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for insuring that the various images cannot control any resources that have not been allocated to that image. Furthermore, software errors in the control of an operating system's allocated resources are prevented from affecting the resources of any other image. Thus, each image of the operating system or each different operating system directly controls a distinct set of allocatable resources within the platform. With respect to hardware resources in a logical partitioned data processing system, these resources are disjointly shared among various partitions. These resources may include, for example, input/output (I/O) adapters, memory DIMMs, non-volatile random access memory (NVRAM), and hard disk drives. Each partition within an LPAR data processing system may be booted and shut down over and over without having to power-cycle the entire data processing system. Currently, a system administrator can load operating systems for a logical partitioned data processing system, but is unable to know whether the operating system is a rogue or unauthorized operating system, one that has been illegally modified. In logical partitioned data processing systems that have been enabled to run multiple operating systems simultaneously, it is critical that a rogue or unauthorized operating system is not allowed to load and execute. This requirement is especially important with operating systems that support simultaneous multithreading (SMT) and sub-processor partitioning (SPP). If an unauthorized operating system is allowed to load, this operating system has automatic privilege levels that are sufficient to allow calls into the platform firmware. With these privileges, an unauthorized operating system may attempt to penetrate the system and at the very least cause a loss of resources through denial of service attack attempts. The problem with an unauthorized operating system is more critical in SMT and SPP enabled systems because the unauthorized operating system may share processor facilities, rather than using isolated processors, and may be able to influence the other partitions to a greater extent. Currently, no mechanisms are present to limit the loading of unauthorized operating systems. Therefore, it would be advantageous to have an improved method, apparatus, and computer instructions for preventing an unauthorized operating system from loading and executing in a logical partitioned data processing system. SUMMARY OF THE INVENTION The present invention provides a method, apparatus, and computer instructions for managing operating systems. A request from an operating system is received in the logical partitioned data processing system to register for access to hardware in the logical partitioned data processing system. The request includes a key code for the operating system. A determination is made as to whether the operating system is an authorized operating system using the key code in response to receiving the request. The operating system is registered if the operating system is the authorized operating system. Otherwise, the operating system is terminated. BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: FIG. 1 is a block diagram of a data processing system in which the present invention may be implemented; FIG. 2 is a block diagram of an exemplary logical partitioned platform in which the present invention may be implemented; FIG. 3 is a diagram illustrating components used in preventing the loading and execution of unauthorized operating systems in a logical partitioned data processing system in accordance with a preferred embodiment of the present invention; FIG. 4 is a flowchart of a process for creating a list of authorized operating systems in accordance with a preferred embodiment of the present invention; FIG. 5 is a flowchart of a process for handling a registration request from an operating system in accordance with a preferred embodiment of the present invention; and FIG. 6 is a flowchart of a process for handling requests for hardware services in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to the figures, and in particular with reference to FIG. 1, a block diagram of a data processing system in which the present invention may be implemented is depicted. Data processing system 100 may be a symmetric multiprocessor (SMP) system including a plurality of processors 101, 102, 103, and 104 connected to system bus 106. For example, data processing system 100 may be an IBM eServer, a product of International Business Machines Corporation in Armonk, N.Y., implemented as a server within a network. Alternatively, a single processor system may be employed. Also connected to system bus 106 is memory controller/cache 108, which provides an interface to a plurality of local memories 160-163. I/O bus bridge 110 is connected to system bus 106 and provides an interface to I/O bus 112. Memory controller/cache 108 and I/O bus bridge 110 may be integrated as depicted. Data processing system 100 is a logical partitioned (LPAR) data processing system. Thus, data processing system 100 may have multiple heterogeneous operating systems (or multiple instances of a single operating system) running simultaneously. Each of these multiple operating systems may have any number of software programs executing within it. Data processing system 100 is logically partitioned such that different PCI I/O adapters 120-121, 128-129, and 136, graphics adapter 148, and hard disk adapter 149 may be assigned to different logical partitions. In this case, graphics adapter 148 provides a connection for a display device (not shown), while hard disk adapter 149 provides a connection to control hard disk 150. Thus, for example, suppose data processing system 100 is divided into three logical partitions, P1, P2, and P3. Each of PCI I/O adapters 120-121, 128-129, 136, graphics adapter 148, hard disk adapter 149, each of host processors 101-104, and memory from local memories 160-163 is assigned to each of the three partitions. In these examples, memories 160-163 may take the form of dual in-line memory modules (DIMMs). DIMMs are not normally assigned on a per DIMM basis to partitions. Instead, a partition will get a portion of the overall memory seen by the platform. For example, processor 101, some portion of memory from local memories 160-163, and I/O adapters 120, 128, and 129 may be assigned to logical partition P1; processors 102-103, some portion of memory from local memories 160-163, and PCI I/O adapters 121 and 136 may be assigned to partition P2; and processor 104, some portion of memory from local memories 160-163, graphics adapter 148 and hard disk adapter 149 may be assigned to logical partition P3. Each operating system executing within data processing system 100 is assigned to a different logical partition. Thus, each operating system executing within data processing system 100 may access only those I/O units that are within its logical partition. Thus, for example, one instance of the Advanced Interactive Executive (AIX) operating system may be executing within partition P1, a second instance (image) of the AIX operating system may be executing within partition P2, and a Linux or OS/400 operating system may be operating within logical partition P3. Peripheral component interconnect (PCI) host bridge 114 connected to I/O bus 112 provides an interface to PCI local bus 115. A number of PCI input/output adapters 120-121 may be connected to PCI bus 115 through PCI-to-PCI bridge 116, PCI bus 118, PCI bus 119, I/O slot 170, and I/O slot 171. PCI-to-PCI bridge 116 provides an interface to PCI bus 118 and PCI bus 119. PCI I/O adapters 120 and 121 are placed into I/O slots 170 and 171, respectively. Typical PCI bus implementations will support between four and eight I/O adapters (i.e. expansion slots for add-in connectors). Each PCI I/O adapter 120-121 provides an interface between data processing system 100 and input/output devices such as, for example, other network computers, which are clients to data processing system 100. An additional PCI host bridge 122 provides an interface for an additional PCI bus 123. PCI bus 123 is connected to a plurality of PCI I/O adapters 128-129. PCI I/O adapters 128-129 may be connected to PCI bus 123 through PCI-to-PCI bridge 124, PCI bus 126, PCI bus 127, I/O slot 172, and I/O slot 173. PCI-to-PCI bridge 124 provides an interface to PCI bus 126 and PCI bus 127. PCI I/O adapters 128 and 129 are placed into I/O slots 172 and 173, respectively. In this manner, additional I/O devices, such as, for example, modems or network adapters may be supported through each of PCI I/O adapters 128-129. In this manner, data processing system 100 allows connections to multiple network computers. A memory mapped graphics adapter 148 inserted into I/O slot 174 may be connected to I/O bus 112 through PCI bus 144, PCI-to-PCI bridge 142, PCI bus 141 and PCI host bridge 140. Hard disk adapter 149 may be placed into I/O slot 175, which is connected to PCI bus 145. In turn, this bus is connected to PCI-to-PCI bridge 142, which is connected to PCI host bridge 140 by PCI bus 141. A PCI host bridge 130 provides an interface for a PCI bus 131 to connect to I/O bus 112. PCI I/O adapter 136 is connected to I/O slot 176, which is connected to PCI-to-PCI bridge 132 by PCI bus 133. PCI-to-PCI bridge 132 is connected to PCI bus 131. This PCI bus also connects PCI host bridge 130 to the service processor mailbox interface and ISA bus access pass-through logic 194 and PCI-to-PCI bridge 132. Service processor mailbox interface and ISA bus access pass-through logic 194 forwards PCI accesses destined to the PCI/ISA bridge 193. NVRAM storage 192 is connected to the ISA bus 196. Service processor 135 is coupled to service processor mailbox interface and ISA bus access pass-through logic 194 through its local PCI bus 195. Service processor 135 is also connected to processors 101-104 via a plurality of JTAG/I2C busses 134. JTAG/I2C busses 134 are a combination of JTAG/scan busses (see IEEE 1149.1) and Phillips I2C busses. However, alternatively, JTAG/I2C busses 134 may be replaced by only Phillips I2C busses or only JTAG/scan busses. All SP-ATTN signals of the host processors 101, 102, 103, and 104 are connected together to an interrupt input signal of the service processor. The service processor 135 has its own local memory 191, and has access to the hardware OP-panel 190. When data processing system 100 is initially powered up, service processor 135 uses the JTAG/I2C busses 134 to interrogate the system (host) processors 101-104, memory controller/cache 108, and I/O bridge 110. At completion of this step, service processor 135 has an inventory and topology understanding of data processing system 100. Service processor 135 also executes Built-In-Self-Tests (BISTs), Basic Assurance Tests (BATs), and memory tests on all elements found by interrogating the host processors 101-104, memory controller/cache 108, and I/O bridge 110. Any error information for failures detected during the BISTs, BATs, and memory tests are gathered and reported by service processor 135. If a meaningful/valid configuration of system resources is still possible after taking out the elements found to be faulty during the BISTs, BATs, and memory tests, then data processing system 100 is allowed to proceed to load executable code into local (host) memories 160-163. Service processor 135 then releases host processors 101-104 for execution of the code loaded into local memory 160-163. While host processors 101-104 are executing code from respective operating systems within data processing system 100, service processor 135 enters a mode of monitoring and reporting errors. The type of items monitored by service processor 135 include, for example, the cooling fan speed and operation, thermal sensors, power supply regulators, and recoverable and non-recoverable errors reported by processors 101-104, local memories 160-163, and I/O bridge 110. Service processor 135 is responsible for saving and reporting error information related to all the monitored items in data processing system 100. Service processor 135 also takes action based on the type of errors and defined thresholds. For example, service processor 135 may take note of excessive recoverable errors on a processor's cache memory and decide that this is predictive of a hard failure. Based on this determination, service processor 135 may mark that resource for deconfiguration during the current running session and future Initial Program Loads (IPLs). IPLs are also sometimes referred to as a “boot” or “bootstrap”. Data processing system 100 may be implemented using various commercially available computer systems. For example, data processing system 100 may be implemented using IBM eServer iSeries Model 840 system available from International Business Machines Corporation. Such a system may support logical partitioning using an OS/400 operating system, which is also available from International Business Machines Corporation. Those of ordinary skill in the art will appreciate that the hardware depicted in FIG. 1 may vary. For example, other peripheral devices, such as optical disk drives and the like, also may be used in addition to or in place of the hardware depicted. The depicted example is not meant to imply architectural limitations with respect to the present invention. With reference now to FIG. 2, a block diagram of an exemplary logical partitioned platform is depicted in which the present invention may be implemented. The hardware in logical partitioned platform 200 may be implemented as, for example, data processing system 100 in FIG. 1. Logical partitioned platform 200 includes partitioned hardware 230, operating systems 202, 204, 206, 208, and partition management firmware 210. Operating systems 202, 204, 206, and 208 may be multiple copies of a single operating system or multiple heterogeneous operating systems simultaneously run on logical partitioned platform 200. These operating systems may be implemented using OS/400, which are designed to interface with a partition management firmware, such as Hypervisor. OS/400 is used only as an example in these illustrative embodiments. Of course, other types of operating systems, such as AIX and linux, may be used depending on the particular implementation. Operating systems 202, 204, 206, and 208 are located in partitions 203, 205, 207, and 209. Hypervisor software is an example of software that may be used to implement partition management firmware 210 and is available from International Business Machines Corporation. Firmware is “software” stored in a memory chip that holds its content without electrical power, such as, for example, read-only memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), and nonvolatile random access memory (nonvolatile RAM). Additionally, these partitions also include partition firmware 211, 213, 215, and 217. Partition firmware 211, 213, 215, and 217 may be implemented using initial boot strap code, IEEE-1275 Standard Open Firmware, and runtime abstraction software (RTAS), which is available from International Business Machines Corporation. When partitions 203, 205, 207, and 209 are instantiated, a copy of boot strap code is loaded onto partitions 203, 205, 207, and 209 by platform firmware 210. Thereafter, control is transferred to the boot strap code with the boot strap code then loading the open firmware and RTAS. The processors associated or assigned to the partitions are then dispatched to the partition's memory to execute the partition firmware. Partitioned hardware 230 includes a plurality of processors 232-238, a plurality of system memory units 240-246, a plurality of input/output (I/O) adapters 248-262, and a storage unit 270. Each of the processors 232-238, memory units 240-246, NVRAM storage 298, and I/O adapters 248-262 may be assigned to one of multiple partitions within logical partitioned platform-200, each of which corresponds to one of operating systems 202, 204, 206, and 208. Partition management firmware 210 performs a number of functions and services for partitions 203, 205, 207, and 209 to create and enforce the partitioning of logical partitioned platform 200. Partition management firmware 210 is a firmware implemented virtual machine identical to the underlying hardware. Thus, partition management firmware 210 allows the simultaneous execution of independent OS images 202, 204, 206, and 208 by virtualizing all the hardware resources of logical partitioned platform 200. Service processor 290 may be used to provide various services, such as processing of platform errors in the partitions. These services also may act as a service agent to report errors back to a vendor, such as International Business Machines Corporation. Operations of the different partitions may be controlled through a hardware management console, such as hardware management console 280. Hardware management console 280 is a separate data processing system from which a system administrator may perform various functions including reallocation of resources to different partitions. The present invention provides an improved method, apparatus, and computer instructions for preventing the loading and execution of unauthorized operating systems. This mechanism is especially useful in logically partitioned data processing systems. The mechanism of the present invention requires a key or key code to be entered through the hardware management console prior to the activation of a partition in which this key code must match this one contained in the operating system. The key code in the operating system is passed to platform firmware, such as platform firmware 210 in FIG. 2. If the key codes match, the operating system is allowed to register and complete loading. Otherwise, the operating system is terminated. With reference now to FIG. 3, a diagram illustrating components used in preventing the loading and execution of unauthorized operating systems in a logical partitioned data processing system is depicted in accordance with a preferred embodiment of the present invention. In this illustrative example, operating systems 300, 302, 304, and 306 are present. These operating systems are similar to those illustrated in FIG. 2 in partitions 203, 205, 207, and 209. Each licensed operating system in these illustrative examples includes an identifying serial number within the code. This serial number is used as a key code. As can be seen, key codes 308, 310, 312, and 314 are present within operating systems 300, 302, 304, and 306. Each of these operating systems pass their key codes to platform firmware, such as hypervisor 316 during the loading and registration phase. This phase is the period of time during which an operating system loads itself into a partition and registers itself to gain access to hardware resources. In these illustrative examples, hypervisor 316 includes verification process 318, which is used to verify that the operating systems that are being loaded are authorized operating systems. In this illustrative embodiment, verification process 318 checks the key code supplied by an operating system for registration with key codes for authorized operating systems. These key codes are located in partition profile 320 in key code list 322. Partition profile 320 is located in a non-volatile memory, such a NVRAM 192 in FIG. 1. If the key code provided by the operating system is valid, hypervisor 316 will register the operating system and allow it continued access to the hardware resources. If the key code provided by the operating system does not match one in key code list 322, the operating system is terminated. Partition profile 320 and key code list 322 is generated by a system administrator having proper access to an HMC in these illustrative examples. A key code is entered for each operating system that is to be loaded on to the LPAR data processing system. These key codes are stored in key code list 322 in partition profile 320. During loading of operating systems 300, 302, 304, and 306, these operating systems will make calls to access hardware as part of the initialization process, prior to the operating systems registering with hypervisor 316. Verification process 318 in hypervisor 316 determines whether the calls made are necessary to load and initialize the operating system before registration occurs. If these calls are needed, the calls are processed and access to the hardware is provided. Otherwise, access to the hardware is prevented and the operating system making an unnecessary hardware call is terminated. Examples of necessary calls include calls to map memory for the operating system. Memory must be mapped by the operating system for resources to function. In a logical partitioned data processing system, platform firmware, such as a hypervisor, controls the hardware, including the memory. Therefore, the memory must be mapped for a physical address to a logical address to allow the use of this memory by the operating system. Another example of necessary calls includes those for I/O. I/O resources are needed to communicate with the outside world. Similar mappings are needed to map a physical address of an I/O adapter into the logical address range used by the operating system. In contrast, unnecessary calls include calls to set or read items such as the time of day or virtual terminal support. In this manner, unauthorized operations systems are prevented from accessing hardware beyond that needed to initialize operating systems to a point where registration may occur. An unauthorized operating system attempting to avoid registration may be terminated using this feature. With reference now to FIG. 4, a flowchart of a process for creating a list of authorized operating systems is depicted in accordance with a preferred embodiment of the present invention. The process illustrated in FIG. 4 may be implemented in software for use on a hardware management console, such as hardware management console 280 in FIG. 2. The process begins by receiving a request to add or change a code key (step 400). Next, user input for key code is received (step 402). The input in step 402 may occur through a graphical user interface provided at a hardware management console. These key codes may be entered as part of creating or modifying a partition profile. Then, the key code is saved in the partition profile (step 404). Next, a determination is made as to whether additional key code additions or changes are present (step 406). If there are not additional key code additions or changes, then the partition profile is saved (step 408) with the process terminating thereafter. Referring back to step 406 if additional key codes or changes are present, then the process returns to step 402 as described above. In these illustrative examples, the partition profile is saved in a data structure in a non-volatile memory, such as NVRAM 192 in FIG. 1. This profile information is used by the platform firmware when an LPAR data processing system boots up or is started. With this information, the mechanism of the present invention may prevent unauthorized operating systems from loading and executing. With reference now to FIG. 5, a flowchart of a process for handling a registration request from an operating system is depicted in accordance with a preferred embodiment of the present invention. The process illustrated in FIG. 5 may be implemented in platform firmware, such as verification process 318 in hypervisor 316 in FIG. 3. The process begins by receiving a registration request from an operating system (step 500). Then, a determination is made as to whether a key code is present in the registration request (step 502). If a key code is present, then the key code in the registration request is compared to a key code list (step 504). The key code list is one that may be generated through a process such as that illustrated in FIG. 4. Next, a determination is made as to whether there is a match (step 506). If a match is present, the operating system is registered (step 508) with the process terminating thereafter. Referring back to step 502, if a key code is not present in the registration request, then the operating system is terminated (step 510). Next, a security message is sent (step 512) with the process terminating thereafter. This security message may include information about the operating system that attempted to load, the time at which the attempt was made, and other information needed to identify the source of the unauthorized operating system. In step 506, if a match is not present between the key code received from the operating system and a key code in the key code list, the process proceeds to step 510 as described above. With reference now to FIG. 6, a flowchart of a process for handling requests for hardware services is depicted in accordance with a preferred embodiment of the present invention. The process illustrated in FIG. 6 may be implemented in platform firmware, such as verification process 318 in hypervisor 316 in FIG. 3. The process begins by receiving a call for a hardware service from an operating system (step 600). Next, a determination is made as to whether the operating system is registered (step 602). In these illustrative examples, a registered operating system is one that has been verified as an authorized operating system, such as through the process illustrated in FIG. 5 above. If the operating system is not registered, then a determination is made as to whether hardware service is needed to set up the operating system (step 604). In step 604, needed hardware services are those needed by the operating system to load and initialize to a point that the operating system is ready to register itself with the platform firmware. Prior to this point, some hardware services are required by the operating system to load and initialize itself for normal operations. Examples of needed hardware services are those to map memory resources and I/O resources for use by the operating system. If the hardware service is needed to set up the operating system, then a call to provide hardware service is processed (step 606) with the process terminating thereafter. Referring back to step 602, if the operating system is registered, then the process terminates. In step 604, if the hardware service is not needed to set up or complete initialization of the operating system, then the operating system is terminated (step 608). Next, a security message is sent (step 610) with the process terminating thereafter. In this manner, this process prevents operating systems from loading and executing without registering with the platform firmware. Thus, the present invention provides an improved method, apparatus, and computer instructions for preventing loading of unauthorized or rogue operating systems. This feature is provided by requiring a key code or some other unique identifier to be sent by the operating system for use in verifying whether the operating system is authorized. Authorized key codes are maintained and compared to the key code provided to the operating system. If a match occurs, the operating system is allowed to continue execution. Otherwise, the operating system is terminated. It is important to note that while the present invention has been described in the context of a fully functioning data processing system, those of ordinary skill in the art will appreciate that the processes of the present invention are capable of being distributed in the form of a computer readable medium of instructions and a variety of forms and that the present invention applies equally regardless of the particular type of signal bearing media actually used to carry out the distribution. Examples of computer readable media include recordable-type media, such as a floppy disk, a hard disk drive, a RAM, CD-ROMs, DVD-ROMs, and transmission-type media, such as digital and analog communications links, wired or wireless communications links using transmission forms, such as, for example, radio frequency and light wave transmissions. The computer readable media may take the form of coded formats that are decoded for actual use in a particular data processing system. The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Technical Field The present invention relates generally to an improved data processing system and in particular to a method, apparatus, and computer instructions for processing data. Still more particularly, the present invention relates to a method, apparatus, and computer instructions for managing operating systems in a logical partitioned data processing system. 2. Description of Related Art Increasingly large symmetric multi-processor data processing systems, such as IBM eServer P690, available from International Business Machines Corporation, DHP9000 Superdome Enterprise Server, available from Hewlett-Packard Company, and the Sunfire 15K server, available from Sun Microsystems, Inc. are not being used as single large data processing systems. Instead, these types of data processing systems are being partitioned and used as smaller systems. These systems are configured as multi-partition enabled systems. In other words, a single physical data processing system has multiple partitions in which each partition has an operating system. These partitions may execute concurrently. When the partitions are made in a logical manner, these systems are also referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platforms resources. These platform allocatable resources include one or more architecturally distinct processors with their interrupt management area, regions of system memory, and input/output (I/O) adapter bus Blots. The partition's resources are represented by the platform's firmware to the operating system image. Each distinct operation system or image of an operating system running within a platform is protected from each other such that software errors on one logical partition cannot affect the correct operations of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for insuring that the various images cannot control any resources that have not been allocated to that image. Furthermore, software errors in the control of an operating system's allocated resources are prevented from affecting the resources of any other image. Thus, each image of the operating system or each different operating system directly controls a distinct set of allocatable resources within the platform. With respect to hardware resources in a logical partitioned data processing system, these resources are disjointly shared among various partitions. These resources may include, for example, input/output (I/O) adapters, memory DIMMs, non-volatile random access memory (NVRAM), and hard disk drives. Each partition within an LPAR data processing system may be booted and shut down over and over without having to power-cycle the entire data processing system. Currently, a system administrator can load operating systems for a logical partitioned data processing system, but is unable to know whether the operating system is a rogue or unauthorized operating system, one that has been illegally modified. In logical partitioned data processing systems that have been enabled to run multiple operating systems simultaneously, it is critical that a rogue or unauthorized operating system is not allowed to load and execute. This requirement is especially important with operating systems that support simultaneous multithreading (SMT) and sub-processor partitioning (SPP). If an unauthorized operating system is allowed to load, this operating system has automatic privilege levels that are sufficient to allow calls into the platform firmware. With these privileges, an unauthorized operating system may attempt to penetrate the system and at the very least cause a loss of resources through denial of service attack attempts. The problem with an unauthorized operating system is more critical in SMT and SPP enabled systems because the unauthorized operating system may share processor facilities, rather than using isolated processors, and may be able to influence the other partitions to a greater extent. Currently, no mechanisms are present to limit the loading of unauthorized operating systems. Therefore, it would be advantageous to have an improved method, apparatus, and computer instructions for preventing an unauthorized operating system from loading and executing in a logical partitioned data processing system. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a method, apparatus, and computer instructions for managing operating systems. A request from an operating system is received in the logical partitioned data processing system to register for access to hardware in the logical partitioned data processing system. The request includes a key code for the operating system. A determination is made as to whether the operating system is an authorized operating system using the key code in response to receiving the request. The operating system is registered if the operating system is the authorized operating system. Otherwise, the operating system is terminated. | 20040325 | 20081209 | 20050929 | 66255.0 | 0 | TRUONG, THANHNGA B | METHOD FOR PREVENTING LOADING AND EXECUTION OF ROGUE OPERATING SYSTEMS IN A LOGICAL PARTITIONED DATA PROCESSING SYSTEM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,810,094 | ACCEPTED | MAC controlled sleep mode/wake-up mode with staged wake-up for power management | A power management scheme for a wireless communications device processor substantially implemented on a single CMOS integrated circuit is described. By incorporating controls for sleep and wake-up mode transitions in the processor's control logic, improved power savings with reduced latency is provided, obviating the need for hardware-focused solutions with elaborate signaling mechanisms. A fully integrated power management with staged wake-up operations controlled by the MAC solution consumes less power than the conventional wireless LAN solutions in standby mode. | 1. A data processor for use in a wireless communication device, comprising: a processing unit; an instruction pipeline circuit; at least one processing module; a timer for generating a time-out interval; and power control logic for detecting a sleep instruction and placing the processing unit, instruction pipeline circuit and at least one processing module in a low-power state, where the power control logic is operative in response to a wake-up signal to reactivate the instruction pipeline circuit, and consequently at least one processing module only to the extent required by the wake-up signal. 2. The processor of claim 1, where the instruction pipeline circuit comprises a multi-stage instruction pipeline circuit. 3. The processor of claim 1, where the wake-up signal comprises a logical OR combination of one or more predetermined wake-up conditions and the time-out interval. 4. The processor of claim 1, where the power control logic comprises instruction decode logic to detect the sleep instruction. 5. The processor of claim 1, where the power control logic comprises branch condition logic to respond to the wake-up signal. 6. The processor of claim 1, where the power control logic, having specified one or more wake-up conditions that the processing unit will respond to when in a low-power state, generates the wake-up signal upon detecting the one or more wake-up conditions or the time-out interval. 7. The processor of claim 1, where the power control logic instructs the instruction pipeline circuit to complete any instructions preceding the sleep instruction. 8. The processor of claim 7, where the power control logic instructs the instruction pipeline circuit to cease fetching new instructions after encountering a sleep instruction whose wake-up conditions are currently deasserted. 9. The processor of claim 1, wherein the processing unit, instruction pipeline circuit and at least one processing module are formed together on a common silicon substrate using CMOS processing. 10. The processor of claim 6, wherein the wake-up conditions and time-out interval are stored in a register by the power control logic. 11. An article of manufacture having at least one recordable medium having stored thereon executable instructions and data which, when executed by at least one processing device, cause the at least one processing device to: detect a sleep instruction for the processing device; specify one or more wake-up conditions and a time-out interval; power down an instruction pipeline and one or more processor modules; reactivate the instruction pipeline upon detection of a wake-up signal corresponding to either a wake-up condition or the time-out interval, and process one or more instructions in the instruction pipeline to reactivate any of the one or more processor modules required to respond to a detected wake-up condition. 12. The article of manufacture of claim 11, wherein the processing device executes any instructions received by the instruction pipeline before the sleep instruction is received. 13. The article of manufacture of claim 11, wherein the instruction pipeline comprises a multistage instruction pipeline, and the processing device reactivates only stages in the multistage instruction pipeline and/or the function units needed to process one or more instructions necessary to analyze and respond to the wake-up signal. 14. The article of manufacture of claim 11, further comprising a register for holding the specified wake-up conditions and time out signal. 15. The article of manufacture of claim 11, where the processing device is implemented as part of a single-chip wireless communication device. 16. The article of manufacture of claim 11, where the executable instructions and data comprise control logic for controlling the operation of the processing device. 17. The article of manufacture of claim 11, where the processing device powers down the one or more processor modules by freezing a clock signal for said one or more modules. 18. The article of manufacture of claim 11, where the processing device powers down the one or more processor modules by placing said one or more modules in an idle mode. 19. A method for managing power in a communications processor by selectively removing one or more processor modules from a standby mode, comprising: storing one or more wake-up conditions and a time-out interval in a register; receiving a processor sleep instruction; executing any pending instructions received by the processor before the sleep instruction; powering down the one or more processor modules; receiving a processor wake-up signal corresponding to one of said wake-up conditions or said time-out interval; powering up only the processor modules required to respond to the detected processor wake-up signal. 20. The method of claim 19, wherein one of the processor modules comprises an instruction pipeline circuit. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to the field of data processing. In one aspect, the present invention relates to a method and system for reducing power consumption in a communications system. 2. Related Art In general, data processors are capable of executing a variety of instructions. Processors are used in a variety of applications, including communication systems formed with wireless and/or wire-lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital amps, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS) and/or variations thereof. Especially with wireless and/or mobile communication devices (such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc.), the processor or processors in a device must be able to run various complex communication programs using only a limited amount of power that is provided by power supplies, such as batteries, contained within such devices. In particular, for a wireless communication device to participate in wireless communications, the device includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). To implement the transceiver function, one or more processors and other modules are used to form a transmitter which typically includes a data modulation stage, one or more intermediate frequency stages and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. Alternatively, in direct conversion transmitters/receivers, conversion directly between baseband signals and RF signals is performed. The power amplifier amplifies the RF signals prior to transmission via an antenna. In addition, one or more processors and other modules are used to form a receiver which is typically coupled to an antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard. Because of the computational intensity (and the associated power consumption by the processor(s)) for such transceiver functions, it is an important goal in the design of wireless and/or mobile communication devices to minimize processor and other module operations (and the associated power consumption). It is particularly crucial for mobile applications in order to extend battery life. The device must provide a high rate of data throughput when necessary, and otherwise enter a low power mode, called a sleep mode, where various modules are deactivated. Such a strategy can greatly decrease the system's average power consumption. With conventional solutions for saving power, a variety of complex circuit and hardware designs have been proposed. These mechanisms exhibit substantial latencies for entering and leaving sleep mode, which restricts the power that can be saved and the range of applicability because these latencies may preclude a processor from being able to deactivate modules before having to reactivate them. Moreover, these mechanisms are burdensome to use, requiring code routines such as an interrupt handler to evaluate and respond to the wake-up conditions. In addition, many implementations are based on complex signaling mechanisms and processor state transitions which require significant hardware and software support and also exhibit long latencies. In addition to the complexity of the computational requirements for a communications transceiver, such as described above, the ever-increasing need for higher speed communications systems imposes additional performance requirements and resulting costs for communications systems. In order to reduce costs, communications systems are increasingly implemented using Very Large Scale Integration (VLSI) techniques. The level of integration of communications systems is constantly increasing to take advantage of advances in integrated circuit manufacturing technology and the resulting cost reductions. This means that communications systems of higher and higher complexity are being implemented in a smaller and smaller number of integrated circuits. For reasons of cost and density of integration, the preferred technology is CMOS. To this end, digital signal processing (“DSP”) techniques generally allow higher levels of complexity and easier scaling to finer geometry technologies than analog techniques, as well as superior testability and manufacturability. Therefore, a need exists for a method and apparatus that provides reduced power consumption with smaller deactivation and/or activation latencies. In addition, a need exists for reducing processor power consumption without requiring complex hardware and elaborate signaling mechanisms. Moreover, a need exists for improved selectivity when determining the nature and extent of the required power-up operations. There is also a need for a better system that is capable of performing the above functions and overcoming these difficulties without increasing circuit area and operational power. Further limitations and disadvantages of conventional systems will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow. SUMMARY OF THE INVENTION Broadly speaking, the present invention provides an improved method and system for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and the required modules necessary to respond to the asserted wake-up conditions. This may be accomplished by issuing a wake-up signal only when specified wake-up conditions are detected, and then only reactivating the necessary components to respond to the wake-up signal. With this approach, a staged wake-up is provided for improved power management with reduced latencies. In accordance with various embodiments of the present invention, a method and apparatus provides a power saving mechanism for a programmable communications processor. The power saving mechanism may be implemented using the MAC layer programming to control the sleep and wake-up modes and to provide for a staged wake-up of various processor modules for improved power management. The host processor may also be subject to this power management. The PSM invokes the power saving mechanism by specifying wake-up conditions and a sleep time-out period, and then executing a sleep instruction until a wake-up condition is detected or the time-out period expires, at which time the wake-up condition is processed to determine what specific circuitry or modules need to be reactivated. In a selected embodiment power control logic is provided for directly awakening some modules, while other modules are awakened by the PSM's instruction once the PSM reawakens. Thus, the present invention provides improved effectiveness, reduced latency, simplified programming and reduced hardware overhead. The objects, advantages and other novel features of the present invention will be apparent from the following detailed description when read in conjunction with the appended claims and attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of a wireless communication system in accordance with an exemplary embodiment of the present invention. FIG. 2 is a schematic block diagram of a wireless communication device in accordance with an exemplary embodiment of the present invention. FIG. 3 is a schematic block diagram of a wireless interface device in accordance with an exemplary embodiment of the present invention. FIG. 4 depicts an exemplary state machine description of an exemplary embodiment of the present invention. FIG. 5 depicts a methodology and program sequence for an exemplary embodiment of the present invention. DETAILED DESCRIPTION A method and apparatus for an improved communications processor is described. While various details are set forth in the following description, it will be appreciated that the present invention may be practiced without these specific details. For example, selected aspects are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention. Some portions of the detailed descriptions provided herein are presented in terms of algorithms or operations on data within a computer memory. Such descriptions and representations are used by those skilled in the data processing arts to describe and convey the substance of their work to others skilled in the art. In general, an algorithm refers to a self-consistent sequence of steps leading to a desired result, where a “step” refers to a manipulation of physical quantities which may, though need not necessarily, take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is common usage to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. These and similar terms may be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions using terms such as processing, computing, calculating, determining, displaying or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and/or transforms data represented as physical, electronic and/or magnetic quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. FIG. 1 illustrates a wireless communication system 10 in which embodiments of the present invention may operate. As illustrated, the wireless communication system 10 includes a plurality of base stations and/or access points 12, 16, a plurality of wireless communication devices 18-32 and a network hardware component 34. The wireless communication devices 18-32 may be laptop host computers 18, 26, personal digital assistant hosts 20, 30, personal computer hosts 32, cellular telephone hosts 28 and/or wireless keyboards, mouse devices or other Bluetooth devices 22, 24. The details of the wireless communication devices will be described in greater detail with reference to FIGS. 2-5. As illustrated, the base stations or access points 12, 16 are operably coupled to the network hardware 34 via local area network connections 36, 38. The network hardware 34 (which may be a router, switch, bridge, modem, system controller, etc.) provides a wide area network connection 42 for the communication system 10. Each of the base stations or access points 12, 16 has an associated antenna or antenna array to communicate with the wireless communication devices in its area. Typically, the wireless communication devices register with a particular base station or access point 12, 16 to receive services from the communication system 10. For direct connections (e.g., point-to-point communications between laptop 26 and mouse or keyboard 22), wireless communication devices communicate directly via an allocated channel. Regardless of the particular type of communication system, each wireless communication device includes a built-in radio and/or is coupled to a radio. The radio includes a highly linear amplifier and/or programmable multi-stage amplifier with a low latency power saving mechanism as disclosed herein to enhance performance, reduce costs, reduce size, reduce power consumption and/or enhance broadband applications. FIG. 2 is a schematic block diagram illustrating a radio implemented in a wireless communication device that includes the host device or module 50 and at least one wireless interface device, or radio transceiver 59. The wireless interface device may be built in components of the host device 50 or externally coupled components. As illustrated, the host device 50 includes a processing module 51, memory 52, peripheral interface 55, input interface 58 and output interface 56. The processing module 51 and memory 52 execute the corresponding instructions that are typically done by the host device. For example, in a cellular telephone device, the processing module 51 performs the corresponding communication functions in accordance with a particular cellular telephone standard. The wireless interface device 59 includes a host interface, a media-specific access control protocol (MAC) layer module, a physical layer module (PHY), a digital-to-analog converter (DAC), and an analog to digital converter (ADC). The peripheral interface 55 allows data to be received from and sent to one or more external devices 65 via the wireless interface device 59. As will be appreciated, the modules in the wireless interface device are implemented with a communications processor and an associated memory for storing and executing instructions that control the access to the physical transmission medium in the wireless network. Each external device includes its own wireless interface device for communicating with the wireless interface device of the host device. For example, the host device may be personal or laptop computer and the external device 65 may be a headset, personal digital assistant, cellular telephone, printer, fax machine, joystick, keyboard, desktop telephone, or access point of a wireless local area network. In this example, external device 65 is an IEEE 802.11 wireless interface device. FIG. 3 is a schematic block diagram of a wireless interface device (i.e., a radio) 60 which includes a host interface 62, digital receiver processing module 64, an analog-to-digital converter (ADC) 66, a filtering/gain module 68, a down-conversion stage 70, a receiver filter 71, a low noise amplifier 72, a transmitter/receiver switch 73, a local oscillation module 74, memory 75, a digital transmitter processing module 76, a digital-to-analog converter (DAC) 78, a filtering/gain module 80, a mixing up-conversion stage 82, a power amplifier 84, and a transmitter filter module 85. The transmitter/receiver switch 73 is coupled to the antenna 87, which may include two antennas coupled through a switch. Still further, the antenna section 61 may include separate multiple antennas 87a, 87b for the transmit path and the receive path of each wireless interface device (as shown in FIG. 3). As will be appreciated, the antenna(s) may be polarized, directional, and be physically separated to provide a minimal amount of interference. The digital receiver processing module 64, the digital transmitter processing module 76 and the memory 75 may execute digital receiver functions and digital transmitter functions in accordance with a particular wireless communication standard. The digital receiver functions include, but are not limited to, digital frequency conversion, demodulation, constellation demapping, decoding and/or descrambling. The digital transmitter functions include, but are not limited to, scrambling, encoding, constellation mapping, modulation and/or digital frequency conversion. The digital receiver and transmitter processing modules 64, 76 may be implemented using a shared processing device, individual processing devices, or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry and/or any device that manipulates signals (analog and/or digital) based on operational instructions. The memory 75 may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, and/or any device that stores digital information. Note that when the processing module 64, 76 implements one or more of its functions via a state machine, analog circuitry, digital circuitry and/or logic circuitry, the memory storing the corresponding operational instructions may be embedded with the circuitry comprising the state machine, analog circuitry, digital circuitry and/or logic circuitry. In operation, the wireless interface device 60 receives outbound data 94 from the host device via the host interface 62. The host interface 62 routes the outbound data 94 to the digital transmitter processing module 76, which processes the outbound data 94 to produce digital transmission formatted data 96 in accordance with a particular wireless communication standard, such as IEEE 802.11 (including all current and future subsections), Bluetooth, etc. The digital transmission formatted data 96 will be a digital base-band signal or a digital low IF signal, where the low IF typically will be in the frequency range of one hundred kilohertz to a few megahertz. Subsequent stages convert the digital transmission formatted data to an RF signal, and may be implemented as follows. The digital-to-analog converter 78 converts the digital transmission formatted data 96 from the digital domain to the analog domain. The filtering/gain module 80 filters and/or adjusts the gain of the analog signal prior to providing it to the up-conversion module 82. The mixing stage 82 directly converts the analog baseband or low IF signal into an RF signal based on a transmitter local oscillation clock 83 provided by local oscillation module 74. The power amplifier 84 amplifies the RF signal to produce outbound RF signal 98, which is filtered by the transmitter filter module 85. The antenna section 61 transmits the outbound RF signal 98 to a targeted device such as a base station, an access point and/or another wireless communication device. The wireless interface device 60 also receives an inbound RF signal 88 via the antenna section 61, which was transmitted by a base station, an access point, or another wireless communication device. The inbound RF signal is converted into digital reception formatted data; this conversion may be implemented as follows. The antenna section 61 provides the inbound RF signal 88 to the receiver filter module 71 via the transmit/receive switch 73, where the receiver filter 71 bandpass filters the inbound RF signal 88. The receiver filter 71 provides the filtered RF signal to low noise amplifier 72, which amplifies the signal 88 to produce an amplified inbound RF signal. The low noise amplifier 72 provides the amplified inbound RF signal to the mixing module 70, which directly converts the amplified inbound RF signal into an inbound low IF signal or baseband signal based on a receiver local oscillation clock 81 provided by local oscillation module 74. The down conversion module 70 provides the inbound low RF signal or baseband signal to the filtering/gain module 68. The filtering/gain module 68 filters and/or gains the inbound low IF signal or the inbound baseband signal to produce a filtered inbound signal. The analog-to-digital converter 66 converts the filtered inbound signal from the analog domain to the digital domain to produce digital reception formatted data 90. The digital receiver processing module 64 decodes, descrambles, demaps, and/or demodulates the digital reception formatted data 90 to recapture inbound data 92 in accordance with the particular wireless communication standard being implemented by wireless interface device. The host interface 62 provides the recaptured inbound data 92 to the host device (e.g., 50) via the peripheral interface (e.g., 55). As will be appreciated, the wireless communication device of FIG. 2 described herein may be implemented using one or more integrated circuits. For example, the host device 50 may be implemented on one integrated circuit, the digital receiver processing module 64, the digital transmitter processing module 76 and memory 75 may be implemented on a second integrated circuit, and the remaining components of the wireless interface device 60 and/or antenna 61, may be implemented on a third integrated circuit. As an alternate example, the wireless interface device 60 may be implemented on a single integrated circuit. As yet another example, the processing module 51 of the host device and the digital receiver and transmitter processing modules 64 and 76 may be a common processing device implemented on a single integrated circuit. Further, the memory 52 and memory 75 may be implemented on a single integrated circuit and/or on the same integrated circuit as the common processing modules of processing module 51 and the digital receiver and transmitter processing module 64 and 76. In a selected embodiment, the present invention shows, for the first time, a fully integrated, single chip 802.11b/g solution with built-in power management that reduces power consumption using an intelligent stand-by mode to provide greatly extended battery life for mobile devices, all implemented in CMOS (Complementary Metal Oxide Semiconductor), as part of a single chip or multi-chip transceiver radio. As for the processor componentry of the wireless interface device or radio, an exemplary depiction of the processor details is illustrated in FIG. 3 as communication processor 100, which shows a system level description of the operation of an embodiment of a communication processor embodiment of the present invention. The communication processor 100 may be an integrated circuit or it may be constructed from discrete components. The communication processor 100 may implement a MAC module using a programmable state machine 102 (which includes the Fetch 141, Decode 143, Read 145, Execute 147 and Write 149 pipeline, in that order). The processor 100 also includes a memory 118, which may be implemented as a data RAM memory and code EPROM memory. Also included in the processor are the transmit/receive queues and supporting hardware 182 (coupled between host interface 181 and PHY interface 183), which may include transmit and receive queues, encryption modules, transmit and receive engines and/or packet processing hardware. For power management of the processor 100, power-management logic 172 is provided, including the wake-up timer 134, logic to select wake-up conditions, and logic to direct modules to deactivate themselves. To reduce the power consumed by processor-related circuits, the present invention provides a power management scheme to extend the battery life of Wi-Fi enabled small mobile devices. In a selected embodiment, the power management scheme uses a software approach to place the transceiver in standby mode and to selectively respond to wake-up commands, thereby reducing power consumption significantly without imposing a performance cost. In mobile device applications, the communications processor is able to spend a majority of its time in standby mode, adding several days of battery life to a PDA. In a selected embodiment illustrated in FIG. 3, power management may be implemented using a wake-up timer 134 and a one or more specified wake-up conditions. The processor 100 may include instruction decode logic and branch condition logic that is configured to detect a sleep instruction and to respond to the wake-up conditions or the timer 134. Once the communications processor 100 completes a high throughput task and/or receives a sleep instruction, the processor 100 prepares to enter sleep mode by specifying a set of conditions that will re-awaken it. The processor 100 then deactivates as many modules as possible. Some deactivations may occur prior to executing the sleep instruction. Once the sleep instruction has entered the instruction pipeline 140 and the preceding instructions in the pipeline have been completed, the remaining nonessential modules (such as the transmit/receive queues and major portions of the programmable state machine, etc.) are powered-down by either freezing their clocks or placing them in an idle mode. When one of the specified conditions is detected, the processor wakes up, analyzes the condition, and reactivates whatever modules are needed to service the condition. As illustrated in FIG. 4, the sleep and wake-up modes described herein may be controlled by a programmable state machine (PSM) in the MAC layer of a communications processor, whereby the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications or host related event. In particular, a processor that is fully or partially active and executing instructions (state 402) executes a power management program (transition 403) which specifies the wake-up conditions to which it will respond, along with a time-out period, any one of which will be used to generate a wake-up signal (state 404). The processor subsequently receives a sleep instruction (transition 405) and changes to a power down state 406. In the power down state 406, the processor and some associated modules are also placed in a sleep mode by disabling power and/or clock signals to the processor modules or otherwise idling the modules. Upon receipt of a wake-up signal (transition 407), a selective reactivation state is entered (state 408), whereby the required processor componentry and/or modules are powered-up based upon the detected wake-up condition. The processor then begins processing the wake-up signal and its associated wake-up condition(s) to proceed (via transition 409) to the fully or partially active instruction execution state (state 402), where the required modules are used to execute the instruction(s) corresponding to the detected wake-up condition. In a selected embodiment, when the PSM wakes up, all of the instruction pipeline stages also wake up to permit the instruction to flow from stage to stage, progressing through fetch/decode, read, execute, and write. FIG. 5 depicts an exemplary power saving methodology and program sequence for the present invention. As an initial step, after having completed any previous communication tasks, the processor 100 specifies the wake-up conditions that will be used to wake up the processor, along with a time-out period, at step 502. For example, the conditions to observe and the wake-up interval may be specified by registers which are loaded by a power saving program. The processor may then deactivate certain nonessential modules, at step 503. In a selected embodiment, these modules are those whose deactivation is controlled by the processor's instructions. With step 503, the PSM's instructions power down some modules (generally by writing appropriate values into the modules' control registers) prior to the PSM's execution of the sleep instruction. The processor detects and executes a sleep instruction at step 504. This sleep instruction detection functionality may be implemented by control logic in the processor 100. In one implementation, the instruction decode logic in the processor 100 may be extended to detect the sleep instruction (step 504). Upon receipt of a sleep instruction, the processor logic determines that preceding instructions in the pipeline 140 have completed (step 506) prior to deactivation. Upon completion of the pending instructions from the pipeline, the processor and its associated modules enter a sleep or standby mode at step 508. In a selected embodiment, if a sleep instruction is encountered (decision 504) when the specified wake-up conditions are de-asserted, the control logic will cease fetching new instructions, wait until any preceding instructions are finished (step 506), and then cause the processor to enter a dormant, low-power state (step 508). The low-power state may be implemented by disabling the clocks for one or more processor modules. In a selected embodiment, these modules are those whose deactivation is directly controlled by the processor's hardware. For any processor modules which require clocks in order to provide data for external devices, these modules may be directed to enter an idle mode. Once the processor is powered down or in standby mode, when one of the specified conditions occurs or if the wake-up interval is reached (detection step 510), the wake-up signal asserts. In a selected implementation, branch condition logic in the processor may be expanded to select multiple conditions and logically OR them together—along with the wake-up timer's output—to form a wake-up signal. At step 512, the wake-up signal is issued to the processor. In a selected embodiment, the wake-up signal is supplied to the control logic which reactivates instruction pipeline 140 to begin fetching the next instruction after the sleep instruction (step 514). Subsequent stages of the pipeline are reactivated as this instruction and those that follow are processed. At step 516, the instructions following the sleep instruction are executed by processor 100 to analyze the asserted wake-up conditions and reactivate the modules that are needed to respond to the wake-up condition (step 518). Rather than reactivating the entire processor and associated modules, the present invention allows for judicious use of power upon wake-up by reactivating only the modules that are needed to service the wake-up condition. Upon completing the required communications tasks, the processor may then specify another set of wake-up conditions and a time-out interval, prior to executing an associated sleep instruction. Optionally, the processor may loop back and repeat some or all of the outlined procedure using the specified wake-up conditions and time-out interval. With the power saving mechanism of the present invention, the deactivation and re-activation latencies may be reduced significantly as compared to conventional hardware-based techniques involving an interrupt handler to facilitate these tasks. Such conventional techniques require elaborate signaling mechanisms and processor state transitions that impose long latencies. Such latencies greatly restrict the amount of power that can be saved as well as the range of situations where modules can be powered-down. In contrast, an implementation of the present invention relies on a sleep instruction along with logic to decode it and respond appropriately, including selection of wake-up signals and a time-out interval, which quickly and efficiently enables selective reactivation of only the processor modules that are required to service the specified wake-up condition, thereby applying only power that is needed to service the wake-up conditions. In particular, effective power saving is obtained by deactivating all instruction pipeline stages (instruction fetch, instruction decode and operand read, execution, and write) and other external modules, and then selectively reactivating only the modules needed to service the wake-up condition. A power saving program embodiment provides low latency standby mode to reduce power consumption with minimum delay, and allows its application to a wide range of situations, including those where high throughput and idle intervals alternate in close proximity. From the programmer's perspective, the power saving mechanism of the present invention is simple to use, requiring specification of wake-up conditions and a wake-up interval and then a single sleep instruction. Little additional program memory is needed for these instructions. From a hardware perspective, the overhead is relatively low with only minor extensions being needed with regard to the instruction decode and branch condition logic, as well as the addition of a count-down timer. As described herein and claimed below, a method and apparatus are provided for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and those modules needed to respond to a communications event. This translates to a very power efficient processor. As will be appreciated, the present invention may be implemented in a computer accessible medium including one or more data structures representative of the circuitry included in the system described herein. Generally speaking, a computer accessible medium may include storage media such as magnetic or optical media, e.g., disk, CD-ROM, or DVD-ROM, volatile or non-volatile memory media such as RAM (e.g., SDRAM, RDRAM, SRAM, etc.), ROM, PROM, EPROM, EEPROM, etc., as well as media accessible via transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link. For example, data structure(s) of the circuitry on the computer accessible medium may be read by a program and used, directly or indirectly, to implement the hardware comprising the circuitry described herein. For example, the data structure(s) may include one or more behavioral-level descriptions or register-transfer level (RTL) descriptions of the hardware functionality in a high level design language (HDL) such as Verilog or VHDL. The description(s) may be read by a synthesis tool which may synthesize the description to produce one or more netlist(s) comprising lists of gates from a synthesis library. The netlist(s) comprise a set of gates which also represent the functionality of the hardware comprising the circuitry. The netlist(s) may then be placed and routed to produce one or more data set(s) describing geometric shapes to be applied to masks. The masks may then be used in various semiconductor fabrication steps to produce a semiconductor circuit or circuits corresponding to the circuitry. Alternatively, the data structure(s) on computer accessible medium may be the netlist(s) (with or without the synthesis library) or the data set(s), as desired. In yet another alternative, the data structures may comprise the output of a schematic program, or netlist(s) or data set(s) derived therefrom. While a computer accessible medium may include a representation of the present invention, other embodiments may include a representation of any portion of the power management system and/or the PSM, memory, supporting hardware modules and power-down logic. While the system and method of the present invention has been described in connection with the preferred embodiment, it is not intended to limit the invention to the particular form set forth, but on the contrary, is intended to cover such alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims so that those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention in its broadest form. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates in general to the field of data processing. In one aspect, the present invention relates to a method and system for reducing power consumption in a communications system. 2. Related Art In general, data processors are capable of executing a variety of instructions. Processors are used in a variety of applications, including communication systems formed with wireless and/or wire-lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital amps, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS) and/or variations thereof. Especially with wireless and/or mobile communication devices (such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc.), the processor or processors in a device must be able to run various complex communication programs using only a limited amount of power that is provided by power supplies, such as batteries, contained within such devices. In particular, for a wireless communication device to participate in wireless communications, the device includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). To implement the transceiver function, one or more processors and other modules are used to form a transmitter which typically includes a data modulation stage, one or more intermediate frequency stages and a power amplifier. The data modulation stage converts raw data into baseband signals in accordance with a particular wireless communication standard. The intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. Alternatively, in direct conversion transmitters/receivers, conversion directly between baseband signals and RF signals is performed. The power amplifier amplifies the RF signals prior to transmission via an antenna. In addition, one or more processors and other modules are used to form a receiver which is typically coupled to an antenna and includes a low noise amplifier, one or more intermediate frequency stages, a filtering stage and a data recovery stage. The low noise amplifier receives inbound RF signals via the antenna and amplifies them. The intermediate frequency stages mix the amplified RF signals with one or more local oscillations to convert the amplified RF signal into baseband signals or intermediate frequency (IF) signals. The filtering stage filters the baseband signals or the IF signals to attenuate unwanted out of band signals to produce filtered signals. The data recovery stage recovers raw data from the filtered signals in accordance with the particular wireless communication standard. Because of the computational intensity (and the associated power consumption by the processor(s)) for such transceiver functions, it is an important goal in the design of wireless and/or mobile communication devices to minimize processor and other module operations (and the associated power consumption). It is particularly crucial for mobile applications in order to extend battery life. The device must provide a high rate of data throughput when necessary, and otherwise enter a low power mode, called a sleep mode, where various modules are deactivated. Such a strategy can greatly decrease the system's average power consumption. With conventional solutions for saving power, a variety of complex circuit and hardware designs have been proposed. These mechanisms exhibit substantial latencies for entering and leaving sleep mode, which restricts the power that can be saved and the range of applicability because these latencies may preclude a processor from being able to deactivate modules before having to reactivate them. Moreover, these mechanisms are burdensome to use, requiring code routines such as an interrupt handler to evaluate and respond to the wake-up conditions. In addition, many implementations are based on complex signaling mechanisms and processor state transitions which require significant hardware and software support and also exhibit long latencies. In addition to the complexity of the computational requirements for a communications transceiver, such as described above, the ever-increasing need for higher speed communications systems imposes additional performance requirements and resulting costs for communications systems. In order to reduce costs, communications systems are increasingly implemented using Very Large Scale Integration (VLSI) techniques. The level of integration of communications systems is constantly increasing to take advantage of advances in integrated circuit manufacturing technology and the resulting cost reductions. This means that communications systems of higher and higher complexity are being implemented in a smaller and smaller number of integrated circuits. For reasons of cost and density of integration, the preferred technology is CMOS. To this end, digital signal processing (“DSP”) techniques generally allow higher levels of complexity and easier scaling to finer geometry technologies than analog techniques, as well as superior testability and manufacturability. Therefore, a need exists for a method and apparatus that provides reduced power consumption with smaller deactivation and/or activation latencies. In addition, a need exists for reducing processor power consumption without requiring complex hardware and elaborate signaling mechanisms. Moreover, a need exists for improved selectivity when determining the nature and extent of the required power-up operations. There is also a need for a better system that is capable of performing the above functions and overcoming these difficulties without increasing circuit area and operational power. Further limitations and disadvantages of conventional systems will become apparent to one of skill in the art after reviewing the remainder of the present application with reference to the drawings and detailed description which follow. | <SOH> SUMMARY OF THE INVENTION <EOH>Broadly speaking, the present invention provides an improved method and system for controlling the sleep and wake-up modes of a processor. Using a PSM (programmable state machine) in the MAC layer of a communications processor, the processor and associated modules may be quickly powered down and efficiently reactivated by powering up only the processor and the required modules necessary to respond to the asserted wake-up conditions. This may be accomplished by issuing a wake-up signal only when specified wake-up conditions are detected, and then only reactivating the necessary components to respond to the wake-up signal. With this approach, a staged wake-up is provided for improved power management with reduced latencies. In accordance with various embodiments of the present invention, a method and apparatus provides a power saving mechanism for a programmable communications processor. The power saving mechanism may be implemented using the MAC layer programming to control the sleep and wake-up modes and to provide for a staged wake-up of various processor modules for improved power management. The host processor may also be subject to this power management. The PSM invokes the power saving mechanism by specifying wake-up conditions and a sleep time-out period, and then executing a sleep instruction until a wake-up condition is detected or the time-out period expires, at which time the wake-up condition is processed to determine what specific circuitry or modules need to be reactivated. In a selected embodiment power control logic is provided for directly awakening some modules, while other modules are awakened by the PSM's instruction once the PSM reawakens. Thus, the present invention provides improved effectiveness, reduced latency, simplified programming and reduced hardware overhead. The objects, advantages and other novel features of the present invention will be apparent from the following detailed description when read in conjunction with the appended claims and attached drawings. | 20040326 | 20090901 | 20050929 | 70862.0 | 0 | WENDELL, ANDREW | MAC CONTROLLED SLEEP MODE/WAKE-UP MODE WITH STAGED WAKE-UP FOR POWER MANAGEMENT | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,810,231 | ACCEPTED | Body fluid collection apparatus | A fluid collection apparatus is provided that includes a housing configured for receipt of fluid and/or tissue for collecting fluid therefrom. A holder is configured with the housing to receive an evacuated tube. The holder can include a needle hub supporting a needle cannula in fluid communication with a port extending into a fluid well of the housing. A sloped bottom surface of the housing directs fluid to the fluid well. A sidewall extension or support component extends downward beyond the sloped bottom surface to allow the housing to be stood upright on a flat surface. In certain embodiments, the apparatus includes a tubular cavity to provide a recessed location of the needle cannula for preventing accidental needle injuries. An optional cap provides further shielding from needle cannula and safely maintains fluid in housing after use. | 1. A fluid collection apparatus comprising: a housing configured for receipt of fluid and having a first surface which defines a needleless first mating portion; and a holder having a first end and a second end configured to receive an evacuated tube, the first end defining a second mating portion on an outer surface thereof which is in fluid communication with the evacuated tube, wherein the first mating portion sealingly engages the second mating portion to establish fluid communication therebetween; and a base disposed with the housing and being configured for support thereof. 2. The apparatus of claim 1 wherein said base has a top opening adapted for receiving said housing. 3. The apparatus of claim 1 wherein said base is adapted for standing on a surface. 4. The apparatus of claim 1 wherein said base is configured to enclose said holder. 5. The apparatus of claim 1 wherein said housing has a flange portion extending radially therefrom that engages said base. 6. The apparatus of claim 1 wherein said base defines at least one rib, the rib defining a step for supporting said housing. 7. The apparatus of claim 1 wherein said base defines a plurality of ribs, the ribs each defining a step for supporting said housing. 8. The apparatus according to claim 1 wherein said base is configured to enclose said housing, said holder and an evacuated tube installed in said holder. 9. The apparatus according to claim 1 wherein said base includes a plurality of sidewall extensions, the sidewall extensions being separated by cutout portions. 10. The apparatus according to claim 1 further comprising a removable cap, the cap being adapted to removably enclose an opening of the housing. 11. The apparatus according to claim 10 wherein said removable cap is adapted to provide a fluid seal with said housing. 12. The apparatus according to claim 10 wherein said removable cap includes a finger grip. 13. A fluid collection apparatus comprising: a housing defining a cavity and being configured for receipt of fluid; and a holder having a first end and a second end configured to receive an evacuated tube, the first end including a port that establishes fluid communication between the evacuated tube and the cavity of the housing, the housing including a removable cap that is adapted to removably enclose an opening of the housing. 14. The apparatus according to claim 13 wherein said removable cap is adapted to provide a fluid seal with said housing. 15. The apparatus according to claim 13 further comprising a base disposed with the housing and being configured for support thereof. 16. The apparatus according to claim 13 wherein the housing defines a well portion disposed adjacent the port of the holder. 17. The fluid collection apparatus according to claim 15 wherein said well portion includes a bottom wall of the housing, the bottom wall being sloped downward to define said well portion. 18. The fluid collection apparatus according to claim 15 wherein said port includes a needle cannula configured for disposal within said evacuated tube. 19. The fluid collection apparatus according to claim 15 wherein said removable cap includes a plurality of snap arms adapted for engaging said housing. 20. A fluid collection apparatus comprising: a housing defining a first chamber and being configured for receipt of fluid; and a holder defining a second chamber configured to receive a collection device having a port, the first chamber being in fluid communication with the second chamber via a passageway; and a removable cap that is adapted to removably enclose an opening of the housing and an opening of the holder. 21. The fluid collection apparatus according to claim 20 wherein said removable cap includes a first cover that encloses the opening of the housing and a second cover that encloses the opening of the holder. 22. The fluid collection apparatus according to claim 21 wherein the first cover and the second cover are hingedly connected. 23. The fluid collection apparatus according to claim 20 wherein a bottom wall of the housing has a sloped configuration. 24. The fluid collection apparatus according to claim 15 wherein the housing and the holder are monolithically formed. | RELATED APPLICATIONS This application is a continuation-in-part of U.S. patent application Ser. No. 10/154,512 filed May 24, 2002, the entire contents of which is hereby incorporated herein by reference. BACKGROUND 1. Technical Field The present disclosure generally relates to fluid collection apparatus, and more particularly, to an apparatus that facilitates fluid collection from an umbilical cord while preventing hazardous exposure to blood and body fluids collected. 2. Background of the Related Art Body fluids, such as blood, urine, etc., can be collected during various medical procedures for analysis. For example, fluid and blood samples are typically collected from an umbilical cord of a newborn infant to ascertain blood type and Rh factor. Collection of umbilical cord blood is also beneficial due to its considerable curative value, e.g., use in bone marrow replacement procedures for treatment of cancer and immuno-deficiency disorders. Further, fetal blood has important commercial and therapeutic use in medical fields, such as, tissue culture, stem cell collection, pharmacology and biological research. Several methods for umbilical cord blood sampling are known. One method includes holding a severed free end of an umbilical cord, still attached to a placenta, over a test tube or container. Blood is drained from the placenta into the test tube or container by milking the umbilical cord. A typical sample requires about 5 cc. This procedure has several disadvantages in that it is awkward to perform, difficult to control the sterility of the collected cord blood and may hazardously expose medical personnel to cord blood due to splattering, etc. In another method, blood is drawn from the umbilical cord vein via a large gauge needle and syringe. This procedure is also awkward to perform and may hazardously expose medical personnel to potential needle sticks. More recently, an umbilical cord segment is clamped on two ends and moved to a collection device or container where the cord blood is drained by removing the clamps from either or both ends. Ultimately, the cord blood must be transferred to a storage container, such as a test tube, to prevent contamination of the blood and minimize hazardous exposure to health care workers. These funnel type collection devices require larger apertures that interface with non-standard wide-mouthed test tubes because they rely on gravity to cause the blood to flow. Other cord blood collection devices include large containers to hold the entire cord segment. The containers are sealed so that vacuum pressure can be used to cause blood to flow through a smaller aperture or needle. Needle type interfaces, however, must include shielding to protect medical personnel. The necessary shielding adds more bulk to the collection device. The above devices disadvantageously expose medical personnel to accidental needle sticks and potentially hazardous body fluids. Needlesticks can, for example, occur during manipulation of a collection device including, assembly, dis-assembly or insertion into a blood vessel of the umbilical cord. Hazards such as, for example, needlesticks, splattering, etc. can present dangerous exposure to fluids contaminated with bacterial diseases, and potentially fatal viral infections such as AIDS, Hepatitis B and C, etc. Attempts have been made to overcome the disadvantages of the prior art and prevent hazardous exposure to blood and body fluids. Some designs employ a needle hood for a needle container which sealingly engages an evacuated tube. See, e.g., U.S. Pat. Nos. 5,915,384 and 5,342,328. Designs of this type, however, still involve the use of a container with a needle and may not adequately prevent hazardous exposure to blood and body fluids. Still other designs employ complicated valve connections between a container and a syringe for receiving collected cord blood. These prior designs, however, may not safely transfer fluid due to their complexity and number of parts. Complex structure can result in high manufacturing costs. Further, these configurations are not easily adapted to existing medical components. Consequently, there remains a need to provide a more satisfactory solution for fluid collection apparatus by overcoming the disadvantages and drawbacks of the prior art. Therefore, it would be desirable to provide a fluid collection apparatus for collection of umbilical cord fluid which prevents hazardous exposure to blood and body fluids and is adaptable to existing medical components. Such a fluid collection apparatus should have reduced complexity to increase reliability and improve fluid collection. It would be highly desirable for the fluid collection apparatus to employ luer connections thereby minimizing the potential for inadvertent needle stick. SUMMARY Accordingly, the present disclosure addresses a need for a fluid collection apparatus which protects practitioners, supporting medical personnel and patients from hazardous exposure during umbilical cord fluid collection. The present disclosure resolves related disadvantages and drawbacks experienced in the prior art. More specifically, the apparatus and method of the present disclosure constitute an important advance in the art of fluid collection by providing an apparatus with reduced complexity and fewer needle interfaces. This structure advantageously improves safety and reliability while lowering manufacturing cost. Moreover, the apparatus does not require needle shields, etc. thereby reducing bulk. Desirably, the fluid collection apparatus employs luer connectors to avoid needle use and increase safety. In one particular embodiment, in accordance with the principles of the present disclosure, a fluid collection apparatus is provided. The fluid collection apparatus includes a housing configured for receipt of fluid and has a first surface which defines a needleless first mating portion. A holder has a first end and a second end configured to receive an evacuated tube. The first end defines a second mating portion on an outer surface thereof which is in fluid communication with the evacuated tube. The first mating portion sealingly engages the second mating portion to establish fluid communication therebetween. The housing may have a cylindrical body portion configured and dimensioned to support at least a portion of an umbilical cord. The first surface of the housing can have a funnel configuration. The first mating portion and the second mating portion may alternatively include a male connector and a female connector. Desirably, the first mating portion engages the second mating portion in a slip interference fit. In another embodiment, the first mating portion has a locking surface that engages the second mating portion to lock the housing with the holder. The housing can be releasably locked with the holder. The locking surface may have a threaded portion that receives the second mating portion. In yet another embodiment, the first end of the holder includes a needle hub supporting a needle cannula in fluid communication with the second mating portion and extending away from the first mating portion. The needle cannula may engage the evacuated tube to establish fluid communication between the first mating portion and the evacuated tube. In an alternate embodiment, an umbilical cord fluid collection apparatus includes a cylindrical housing defining a cavity for receipt of at least a portion of an umbilical cord. The housing has a funnel surface which defines a male luer connector. A holder has a first end and a second end configured to receive an evacuated tube. The first end defines a female luer connector on an outer surface thereof in fluid communication with an inner surface of the first end. The inner surface is in fluid communication with the evacuated tube. The male luer connector sealingly engages the female luer connector to establish fluid communication between the male luer connector and the evacuated tube. The configuration of the male luer connector of the housing advantageously facilitates adaptability to pre-existing holders having female luer connectors. The funnel surface may have a locking surface that engages the first end to lock the housing with the holder. The locking surface may be disposed about the male luer connector and includes a threaded portion that receives the first end of the holder. The inner surface of the first end can include a needle hub supporting a needle cannula in fluid communication with the female luer connector and extending away from the male luer connector. The needle cannula may engage the evacuated tube to establish fluid communication between the male luer connector and the evacuated tube. A method for collecting umbilical cord fluid is provided including the steps of: providing a fluid collection apparatus, similar to those described, attaching a first mating portion to a second mating portion to form a non-puncturing seal therebetween; disposing umbilical cord fluid in a housing; inserting an evacuated tube with a holder to establish fluid communication between the second mating portion and the evacuated tube such that umbilical cord fluid is collected in the evacuated tube. The step of providing may include an inner surface of a first end of the holder having a needle cannula extending away from the first mating portion such that the step of inserting includes puncturing the evacuated tube with the needle cannula to establish fluid communication between the second mating portion and the evacuated tube. Another particular embodiment of a fluid collection apparatus according to the present disclosure includes a support for standing the apparatus. As in the embodiments described above, a fluid collection apparatus includes a housing configured for receipt of fluid. The housing has a first surface which defines a needleless first mating portion. A holder having a first end and a second end is configured to receive an evacuated tube. The first end defines a second mating portion on an outer surface thereof which is in fluid communication with the evacuated tube. The first mating portion sealingly engages the second mating portion to establish fluid communication therebetween. A base disposed with the housing and being configured for support thereof. In the particular embodiment, the base has a top opening adapted for receiving the housing. The base is adapted for standing on a surface and is configured to enclose the holder. The housing can have a flange portion extending radially therefrom that engages the base. In at least one embodiment, the base defines at least one rib which forms a step for supporting the housing. Similarly, the base can define a plurality of ribs, each forming a step for supporting the housing. The base can also includes a plurality of sidewall extensions separated by cutout portions. In an illustrative embodiment according to the present disclosure, the base is configured to enclose the housing when the housing is fitted to a holder with an evacuated tube installed in the holder. Particular embodiments of apparatus according to the present disclosure also include a removable cap adapted to removably enclose an opening of the housing. The removable cap is adapted to provide a fluid seal with said housing. An illustrative embodiment of such a cap includes a finger grip or similar gripping portion to aid in removal from the opening of the housing. Another illustrative embodiment of the present disclosure includes a housing defining a cavity and being configured for receipt of fluid. A holder having a first end and a second end is configured to receive an evacuated tube. The first end includes a port that establishes fluid communication between the evacuated tube and the cavity of the housing. The port includes a needle cannula configured for disposal within the evacuated tube. The housing defines a well portion disposed adjacent the port of the holder. A bottom wall of the housing is sloped downward to define the well portion. A removable cap can be adapted to removably enclose an opening of the housing and provide a fluid seal with the housing. The removable cap can also include a plurality of snap arms adapted for engaging the housing. A base can be disposed with the housing and configured for support thereof. In still another embodiment of the present disclosure, a fluid collection apparatus includes a housing defining a first chamber. The housing is configured for receipt of fluid and a bottom wall of the housing has a sloped configuration. A holder defines a second chamber configured to receive a collection device having a port. The first chamber is in fluid communication with the second chamber via a passageway. A removable cap is adapted to removably enclose an opening of the housing and an opening of the holder. In a particular embodiment, the removable cap includes a first cover that encloses the opening of the housing and a second cover that encloses the opening of the holder. The first cover and the second cover can be hingedly connected, for example. In another particular embodiment, the housing and the holder are monolithically formed. BRIEF DESCRIPTION OF THE DRAWINGS The objects and features of the present disclosure are set forth with particularity in the appended claims. The present disclosure, as to its organization and manner of operation, together with further objectives and advantages may be understood by reference to the following description, taken in connection with the accompanying drawings, in which: FIG. 1 is an enlarged side view, in part cross section, of one particular embodiment of a housing of a fluid collection apparatus, in accordance with the principles of the present disclosure; FIG. 2 is a front plan view of the housing shown in FIG. 1; FIG. 3 is a side perspective view of the housing shown in FIG. 1; FIG. 4 is a side perspective view of the housing shown in FIG. 3 and a holder of the fluid collection apparatus; FIG. 5 is a side perspective view of the housing and the holder shown in FIG. 4, assembled, and an evacuation tube of the fluid collection apparatus; FIG. 6 is a side perspective view of the assembled fluid collection apparatus shown in FIG. 5 collecting fluid from an umbilical cord; FIG. 7 is a side perspective view of the fluid collection apparatus shown in FIG. 5 upon collection of fluid; FIG. 8 is a front cross sectional view a the fluid collection apparatus having a support according to a particular embodiment of the present disclosure; FIG. 9 is a front cross sectional view a the fluid collection apparatus having a support according to an alternative embodiment of the present disclosure; FIG. 10 is a front cross sectional view of a fluid apparatus according to the present disclosure having housing extensions forming a support according to an illustrative embodiment of the present disclosure; FIG. 11A is a front cross sectional view of a cap adapted to cover a housing according to an embodiment of the present disclosure; FIG. 11B is a partial front cross sectional view of an optional cap retention feature according to an illustrative embodiment of the present disclosure; FIG. 12 is a front cross sectional view of a particular embodiment of a fluid collection apparatus according to the present disclosure having a cap with a tubular cavity disposed therein for receiving a fluid collection tube; FIG. 13A is a cross sectional plan view of a multi-chamber fluid collection apparatus according to the present disclosure; FIG. 13B is a front cross sectional view of a multi-chamber fluid collection apparatus according to the present disclosure; FIG. 13C is a front cross sectional view of a multi-chamber fluid collection apparatus according to the present disclosure having a fluid collection holder installed therein; and FIG. 13D is a front cross sectional view of a multi-chamber fluid collection apparatus according to the present disclosure having a cap installed therewith. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The exemplary embodiments of the fluid collection apparatus and methods of operation disclosed are discussed in terms of a fluid collecting device, and more particularly in terms of an umbilical cord blood collection apparatus that mates its constituent parts with a fluid collection holder that prevents hazardous exposure to blood and body fluids including, for example, inadvertent needle stick. It is contemplated that a housing of the fluid collection apparatus uses a needless mating connection to increase safety during use including storage, transport, fluid collection, subsequent thereto, etc. It is envisioned that the present disclosure, however, finds application to a wide variety of fluid collection procedures relating to analysis, sampling, diagnosis, treatment, etc. It is further envisioned that the present disclosure may be employed for collection of various body fluids including those relating to phlebotomy, digestive, intestinal, urinary, veterinary, etc. It is contemplated that the components of the fluid collection apparatus may be utilized with other medical application devices including phlebotomy devices, catheters, catheter introducers, guide wire introducers, and those employed during procedures relating to spinal and epidural, biopsy, aphaeresis, dialysis, etc. In the discussion that follows, the term “proximal” refers to a portion of a structure that is closer to a practitioner, and the term “distal” refers to a portion that is further from the practitioner. As used herein, the term “subject” refers to a patient that has blood and/or fluid collected therefrom using a fluid collection apparatus. According to the present disclosure, the term practitioner refers to an individual performing fluid collection, installing, assembling or removing the fluid collection apparatus and may include support personnel. The following discussion includes a description of the fluid collection apparatus, followed by a description of the method of operating the fluid collection apparatus in accordance with the present disclosure. Reference will now be made in detail to the exemplary embodiments of the disclosure, which are illustrated in the accompanying figures. Turning now to the figures, wherein like components are designated by like reference numerals throughout the several views. Referring initially to FIGS. 1 and 2, there is illustrated a cylindrical housing 12 of an umbilical cord fluid collection apparatus 10 (FIG. 5), constructed in accordance with the principles of the present disclosure. Fluid collection apparatus 10 is advantageously configured to prevent hazardous exposure to blood and body fluids by providing a needleless sealing engagement between housing 12 and the components of fluid collection apparatus 10, as will be discussed. The design of fluid collection apparatus 10 provides improved reliability and reduces associated manufacturing costs. Housing 12 is configured for receipt of a fluid, such as, for example, umbilical cord blood 13 (FIG. 6) and defines a cavity 14 for receipt of at least a portion of an umbilical cord 16 (FIG. 5). Cavity 14 is cylindrical, however, it is contemplated that the cavity may have other geometric configurations, such as, for example, rectangular, etc., according to the particular requirements of a medical application. Housing 12 has a first surface, such as, for example, a funnel 18. Funnel 18 is configured to direct cord fluid accumulation toward a central section thereof and consequently in position for collection into an evacuated tube 28 (FIG. 5). It is contemplated that gravity and/or a vacuum force from evacuated tube 28 cooperates with funnel 18 to draw fluid therethrough. It is envisioned that the first surface of housing 12 may have other orientations such as, for example, planar, etc. Funnel 18 defines a first mating portion, such as, for example, a male luer connector 20 to facilitate a needless sealing engagement with a fluid collection holder 22, as shown in FIG. 4, and discussed below. Holder 22 has first end 24 that longitudinally extends to a second end 26. Holder 22 is substantially cylindrical and defines a tubular cavity 27. Second end 26 is configured to receive evacuated tube 28 for disposal within cavity 27. It is contemplated that cavity 27 may have various geometric cross-sections, such as, for example, circular, rectangular, etc. according to the requirements of a particular medical application. First end 24 defines a second mating portion, such as, for example, a female luer connector 30 on outer surface 32 thereof. Female luer connector 30 engages male luer connector 20, as will be discussed, to form a needleless seal and facilitate transfer of cord blood 13 to evacuated tube 28. Female luer connector 30 is in fluid communication with an inner surface 34 of first end 24 which is in fluid communication with evacuated tube 28. In an alternate embodiment, the first mating portion may define a female luer connector, similar to connector 30, and the second mating portion may define a male luer connector, similar to connector 20. Male luer connector 20 sealingly engages female luer connector 30 to establish fluid communication between male luer connector 20 and evacuated tube 28 thereby facilitating cord blood collection from umbilical cord 16 for appropriate sampling, analysis, etc. The sealing engagement of male luer connector 20 and female luer connector 30, in accordance with the principles of the present disclosure, advantageously prevents hazardous exposure to blood and body fluids by eliminating a needle seal and/or connection of housing 12 and the parts of fluid collection apparatus 10. This structure reduces the number of needles employed to facilitate cord blood collection thereby increasing safety to practitioners and subjects. Further, the configuration of male luer connector 20 of housing 12 facilitates adaptability to pre-existing holders having female luer connectors. Fluid collection apparatus 10 is contemplated for use in the medical field of body fluid collection. More particularly, fluid collection apparatus 10 is envisioned to be a disposable device for collecting umbilical cord fluids and having, among other things, safety features that include a needleless mating connection thereby preventing inadvertent needle sticking and hazardous exposure to blood and body fluids from practitioners and subjects, as well as uniform operation during a procedure. The above advantages, among others, realized from the present disclosure are attained through the disclosed fluid collection apparatus 10, as discussed herein. The features of the present disclosure advantageously facilitate safe collection of body fluids. Fluid collection apparatus 10 is integrally assembled of its component parts. Alternatively, portions of fluid collection apparatus 10 can be monolithically formed and assembled therewith. Component parts of fluid collection apparatus 10 can be fabricated from a material suitable for medical applications, for example, polymerics or metals, such as stainless steel, depending on the particular medical application and/or preference of a practitioner. Semi-rigid and rigid polymerics are contemplated for fabrication, as well as resilient materials, such as molded medical grade polypropylene. However, one skilled in the art will realize that other materials and fabrication methods suitable for assembly and manufacture, in accordance with the present disclosure, also would be appropriate. Housing 12 defines a flange 36 disposed adjacent and about an opening 38 of cavity 14. Flange 36 provides stability to housing 12 and facilitates manipulation thereof. It is contemplated that flange 36 may be variously disposed about housing 12. It is further contemplated that housing 12 may not include a flange. Cavity 14 is defined by walls 40 of housing 12. Cavity 14 has a reduced dimension and is appropriately sized to receive a portion of umbilical cord 16. Consequently, housing 12 is smaller and easier to manipulate. It is contemplated that housing 12 may be dimensioned to support an entire umbilical cord and/or various portions thereof. Housing 12 corresponds to the configuration of cavity 14, however, the outer surface of housing 12 may alternatively have geometric configurations, such as, for example, rectangular, elliptical, etc. Funnel 18 tapers from walls 40 to male luer connector 20 to direct cord blood collected in cavity 14 to male luer connector 20. Varying degrees of funnel taper may be employed according to the requirements of a particular fluid collection application and/or preference of a practitioner. Male luer connector 20 extends a sufficient length from funnel 18 to mate with female luer connector 30 of holder 22 in a slip interference fit. The slip interference fit includes a frictional engagement that maintains connectors 20, 30 in a sealing engagement. Female luer connector 30 correspondingly has a receiving depth at least a sufficient dimension to facilitate the slip interference fit with male luer connector 26. The slip interference fit provides a needleless sealing engagement that avoids the use of a needle and prevents hazardous exposure to cord blood. Male luer connector has a tapered outer surface 44 that is configured to engage a tapered inner surface 46 of female luer connector 30. As outer surface 44 is caused to engage inner surface 46, sufficient friction is created therebetween to generate the slip interference fit and seal housing 12 with holder 22. The sealing engagement facilitates transfer of cord blood to evacuated tube 28 while avoiding needlesticks, splattering, etc. It is contemplated that surfaces 44, 46 may have variously tapered configurations, including non-tapered, depending on the sealing strength, etc. requirements of a particular medical application. It is further contemplated that male luer connector 20 may sealingly engage female luer connector 30 in various types of sealing engagements, such as, threaded friction fits, gasket, etc. sufficient to form a seal which facilitates fluid communication between housing 12 and evacuated tube 28. Male luer connector 20 has an opening 42 that is appropriately dimensioned to facilitate passage of fluid therethrough and avoid blockage due to particles, etc. in the cord blood and fluid. It is envisioned that opening 42 may include screens, filters, etc. As shown in FIG. 3, a locking surface 48 extends from funnel 18 and is disposed circumferentially about male luer connector 20. Locking surface 48, including a threaded portion 50, extends an adequate length to receive a correspondingly threaded flange 52 of female luer connector 30. Flange 52 threads with portion 50 to releasably lock housing 12 with holder 22. Locking surface 48 may alternatively comprise circumferential notches disposed along male luer connector 20 which engage corresponding ridges of female luer connector 30 in a locked engagement. Other locking surfaces are contemplated such as, clips, catches, etc. It is contemplated that the locking surfaces may be permanent. Referring to FIGS. 5 and 6, first end 24 of holder 22 has an inner surface 34. Inner surface 34 has a needle hub 54 supporting a needle cannula 56. Needle cannula 56 extends away from male luer connector 20 for appropriate puncture of a rubber stopper 58 of evacuated tube 28. Needle hub 54 and needle cannula 56 are in fluid communication with female luer connector 30. Needle cannula 56 engages rubber stopper 58 to establish fluid communication between male luer connector 20 and evacuated tube 28. Needle cannula 56 punctures rubber stopper 58 such that the tip of needle cannula 56 is disposed in the evacuated space of tube 28. As needle cannula 56 communicates atmospheric pressure to the evacuated space of tube 28 via the fluid communication between housing 12 and evacuated tube 28, cord blood 13 disposed in funnel 18 is drawn through male luer connector 20, female luer connector 30, needle hub 54 and needle cannula 56 into tube 28. Cord blood 13 is drawn through this fluid flow path as pressure within tube 28 stabilizes to atmospheric pressure and the vacuum draws fluid therein. This fluid collection process is continued until tube 28 is filled or a desired amount of cord blood 13 is collected. Tube 28 is removed from needle cannula 56. In use, fluid collection apparatus 10 and its component parts, similar to that described, is properly sterilized and otherwise prepared for storage, shipment and use. Referring to FIGS. 4-7, a practitioner prepares the necessary instruments, including fluid collection apparatus 10 for collecting blood from an umbilical cord of a newborn. It is envisioned that component parts of fluid collection apparatus 10 employed, such as, for example, holder 22, as described, may include pre-existing medical equipment for which housing 12 is easily adapted for use. As shown in FIGS. 4 and 5, male luer connector 20 is mated to female luer connector 30 such that a non-puncturing sealing engagement is formed therebetween. Consequently, a seal is formed between housing 12 and holder 22. Flange 52 threads with locking surface 48 to lock housing 12 with holder 22. A length of umbilical cord 16, which includes arteries, veins, etc. is clamped with surgical clamps (not shown) or the like. The length of umbilical cord 16 should be adequate for sampling, such as, for example, 8-30 centimeters. As shown in FIG. 6, an end 60 of the length of umbilical cord 16 is placed in housing 12. It is not required that the entire length of umbilical cord 16 be disposed within cavity 14 of housing 12. Cord blood 13 is caused to flow into cavity 14 and pool in funnel 16. Cord blood 13, due to the fluid flow path communicating between housing 12 and female luer connector 30, and gravity, flows to needle hub 54 and needle cannula 56. Evacuated tube 28 is inserted within cavity 27 of holder 22 to establish fluid communication between female luer connector 30 and evacuated tube 28 for collecting cord blood 13 via second end 26. Rubber stopper 58 is driven into cavity 27 such that needle cannula 56 punctures rubber stopper 58. Needle cannula 56 is disposed in the evacuated space of tube 28. As discussed, cord blood 13 is drawn into the evacuated space of tube 28. The collection of cord blood 13 is facilitated by the fluid communication established via the needless sealing engagement of male luer connector 20 and female luer connector 30. Housing 12 is drained of the remaining cord blood 13, filling of tube 28 and/or acquisition of a sufficient sample. Tube 28 is removed from needle cannula 56 to discontinue cord blood collection, as shown in FIG. 7. The components of fluid collection apparatus 10 may be disposed and the cord blood sample may be analyzed, etc. In an alternate embodiment, as shown in FIGS. 8-10, housing 12 is maintained in an upright orientation by a base 66 that is disposed with housing 12 and configured for support thereof. Base 66 can be assembled with housing 12 or integrally formed therewith. Referring to FIG. 8 base 66 is adapted to fit around the body of housing 12 and holds housing 12 upright by supporting flange portions 67 that extend radially from housing top edge 70. In an illustrative embodiment, support top edge 72 defines a top opening 74 adapted for accepting the body of housing 12. Bottom edge 76 of base 66 provides a level support for standing housing 12 on a surface, such as, for example, a tabletop, work surface, etc. Base 66 is configured to enclose holder 22 and has a height sufficient to support housing 12 and holder 22 installed therewith. Alternatively, a base may be provided with sufficient height to support housing 12, holder 22 and an evacuated tube (not shown) installed in holder 22 above a flat surface. It is envisioned that base 66 can be embodied as a hollow cylinder having a top opening diameter greater than housing 12 outside diameter but less than the radial extension of flange portions 67. The hollow cylinder can have a circular cross section or it may be formed as a rectangular cylinder, truncated cone or any such structure having a top opening capable of accepting housing 12 and holder 22 together and supporting them in an upright orientation. It is further envisioned that base 66 may include other configurations, such as, for example, solid portions, side wall openings, columns, etc. Base 66 may be formed from a suitable inexpensive manufacturing material, such as, for example polyethylene, polypropylene, nylon, PVC or the like. Base 66 may be fabricated using a number of alternative common manufacturing process. For example, it is envisioned that a cylindrical base 66 can be inexpensively manufactured using an extrusion process or alternatively may be injection molded. An injection molded base 66 may also include a sidewall having a number of cut-outs (not shown) to reduce material usage, provided sufficient structural integrity is maintained to support a blood filled housing and holder with an evacuated tube installed therein, for example. Base 66 may be designed with an inside diameter or cross sectional shape adapted to match the outside diameter or cross sectional shape of housing for a press-fit therewith. A press-fit base 66 can eliminate the need for a flange or similar support features on housing 12 against which to abut support top edge 72. Alternatively, attachment structure may be provided on the inside surface of base 66 and/or outside surface of housing 12 to secure housing 12 within base 66. For example, threads, snap arms, annular grove/ring features and the like can be provided on adjacent surfaces of housing 12 and base 66 for attaching one to the other. In another alternative embodiment, an adhesive material or epoxy may be used to secure base 66 to housing 12. In another embodiment, as shown in FIG. 9, a base 80, similar to that described above, is provided to support housing 12 in an upright orientation. Base 80 is adapted to fit around bottom portion 83 of housing 12 and holds housing 12 upright by supporting housing bottom edge 82 on step 86. Base 80 includes a top edge 85 that defines a top opening adapted for accepting the body of housing 12. Bottom edge 90 of base 80 provides a level support base for standing base 80 on a flat surface. Base 80 includes an inside surface having at least one rib 88 extending inward therefrom. Rib 88 extends from bottom edge 90 along a partial height of base 80 and terminates at a height defining a step 86 for supporting housing 12. Step 86 can be horizontal or angled to match an inclined bottom surface of housing 12, for example. Base 80 has a height sufficient to support housing 12 and holder 22 installed therewith. Alternatively, base 80 may be provided with sufficient height to support housing 12, holder 22 and an evacuated tube (not shown) installed in holder 22 above a flat surface. It is envisioned that base 80 has a circular cross section or it may be formed as a rectangular cylinder, truncated cone or any such structure having a top opening capable of accepting bottom portion 83 of housing 12 and holder 22 together and supporting housing 12 and holder 22 in an upright orientation. Alternatively, base 80 may be designed with an inside diameter or cross sectional shape adapted to match the outside diameter or cross sectional shape of bottom portion 83 of housing 12 for a press-fit therewith. A press-fit base 80 can eliminate the need for ribs having a step or similar support features. Attachment structure, adhesive, etc. may be provided to secure housing 12 within base 80. In another alternate embodiment, as shown in FIG. 10, the base, similar to that described, includes a wall extension 92 that extends from bottom portion 83 of housing 12. Bottom edge 94 of wall extension 92 provides a level support base for standing housing 12 on a flat surface. Wall extension 92 has a height sufficient to support housing 12 and holder 22 installed therewith. Alternatively, a wall extension 92 may be provided with sufficient height to support housing 12, holder 22 and an evacuated tube (not shown) installed in holder 22 above a flat surface. Wall extensions 92 are separated by a pluraltiy of cut-outs 98. Cut-outs 98 may have alternative configurations and dimensions according to the particular strength and material usage requirements for a particular application. The base may include one or a plurality of cut-outs 98. The fluid collection apparatus according to the present disclosure may also include a removable cap 100 adapted to cover the top opening of housing 12 and provide a fluid seal with the top portion of housing 12. Referring to FIG. 11A, a removable cap 100 includes a sealing portion 104 capable of fitting against the housing 12 to provide a fluid seal therebetween. In the illustrative embodiment, the diameter of sealing portion 104 corresponds to inside diameter of housing 12 to provide a press fit therebetween. Sealing portion 104 can optionally include an elastomeric o-ring or the like to provide a more robust fluid seal. Attachment of removable cap 100 to housing 12 can alternatively be provided by mating threads in cap and housing, snap arms, annular ring/groove or bump feature 106 (FIG. 11B) with a corresponding recess (not shown) in housing 12 or the like. A gripping portion such as finger grip 102 can be provided to facilitate easy removal of cap 100 from housing 12. Cap 100 can be formed as a separate component or can be monolithically formed with housing 12, for example, using at least one living hinge. In another embodiment of the fluid collection apparatus, a holder 114, similar to that described, includes a removable cap 106, similar to that described above, as shown in FIG. 12. Cap 106 is provided to cover housing 12 and provide a fluid seal therebetween. Holder 114 includes an orifice 108 adapted for mounting a cannula 56. A cannula 56 extends from orifice 108 toward the outside of housing 12 when cap 106 is installed on housing 12. Cannula 56 is in fluid communication through orifice 108 with a tube 110 having a port 112 opening inside housing 12 when cap 106 is installed to housing 12. Tube 110 extends toward the bottom of housing 12 to submerge port 112 in fluid collected therein. Holder 114 is adapted to receive an evacuated fluid collection tube 130. Sidewall 116 of holder 114 extends into the cavity defined by housing 12 forming a cylinder having an open top and a bottom wall 118. Orifice 108 is disposed through bottom wall 118 such that cannula 56 extends into the tubular cavity defined by holder 114. Tube 110 extends from bottom wall 118 into the cavity defined by housing 12. Housing 12 has a tapered bottom surface 120 defining a well portion 122 for collecting fluid. Port 112 is disposed in well portion 122 for improved fluid collection. Housing 12 can also include sidewall extensions 124 extending below tapered bottom walls such that housing is capable of being stood upright on a flat surface. Alternatively, a separate support 66 (FIG. 8) or base 80 (FIG. 9) can be used to support housing 12 on a flat surface. Cannula 56 and tube 110 are optionally provided as a prefabricated sub-assembly such as cannula 56 and hub 54 assembly used in fluid collection holder described hereinbefore (FIGS. 4-7). Orifice 108 is dimensioned to provide an interference fit with hub 54 whereby hub supports cannula 56 and tube 110 therein. Cannula 56 can optionally include a rubber valve disposed thereon as known in the art. Cap 106 covers top opening of housing 12 and provides a fluid seal with the top portion of housing 12. A sealing portion 104 capable of fitting against the housing 12 provides a fluid seal therebetween. In the illustrative embodiment, the diameter of sealing portion 104 corresponds to inside diameter of housing 12 to provide a press fit therebetween. An optional re-sealable fluid vent (not shown) can be provided in cap 108 or housing 12 to facilitate aspiration of fluid into an evacuated tube by allowing air under atmospheric pressure into housing. To operate the illustrative embodiment shown in FIG. 12, a cap 106 is first removed if one is installed to housing, for example, for shipping and packaging purposes. A fluid sample, such as an umbilical cord section having blood draining therefrom is placed in the cavity of housing 12. Cap 106 is then installed to housing 12 such that port 108 is immersed in fluid to be collected. An evacuated tube 130 having a rubber stopper 132 is placed over cannula 56 and pushed down onto cannula 56 such that cannula 56 punctures rubber stopper 132 and provides a fluid passageway from the cavity of housing 12 into the evacuated fluid collection tube 130. Vacuum pressure in evacuated tube 130 causes fluid to flow upward through port 112, tube 110, cannula 56 and into evacuated tube 130. When a sufficient fluid sample is collected into fluid collection tube 130, fluid collection tube 130 is removed from cannula 56. In at least one embodiment, rubber valve (not shown) self-seals around needle cannula 56 and rubber stopper 132 self-seals collection tube 130. The cavity formed by sidewall 116 is deep enough to contain the entire length of cannula 56 to thereby protect users from accidental needle-stick injuries. In a particular embodiment, a closable fluid vent (not shown) is also provided in cap 106 and/or housing 12. In operation the closable vent is opened to allow air to flow into cavity of housing 12 under atmospheric pressure while a collection tube 130 is installed on cannula 56 to aid aspiration of fluid into evacuated tube. Clinicians are thereby provided with a method and apparatus to efficiently and safely collect fluid samples such as umbilical cord blood while maintaining collected fluid, waste fluid and tissue in safely sealed containers. The fluid collection apparatus according to the embodiment shown in FIG. 12 also provides protection from exposure to needle stick hazards. Turning now to FIGS. 13A-13D, another embodiment of the present disclosure provides a fluid collection apparatus having a housing 138 that defines chambers 140, 142 and a passageway 144 therebetween. A housing, such as, for example, first chamber 140 is adapted for receiving a fluid sample such as an umbilical cord section having blood draining therefrom, and a holder, such as, for example, second chamber 142 is adapted for collecting fluid therefrom. A sloped bottom surface 146 directs fluid from first chamber 140 to second chamber 142 through passageway 144. Housing 138 includes an extension 145 defining a base portion having a bottom edge 147 adapted for standing on a surface. Housing 138 may include one or a plurality of chambers. Housing 138 includes a sidewall 139 and bottom surface 146 that define a cavity with first and second chambers 140, 142. Second chamber 142 is adapted to receive a collection tube holder 150. Collection tube holder 150 has a body portion 152 defining a tubular cavity 154 for receiving an evacuated tube. Tubular cavity 154 has a top opening 156 and a bottom wall 158 with a hub 160 extending through bottom wall 158. A port 164 extends from hub 160 into second chamber 142. A cannula 162 extends from hub 160 toward top opening 156. Cannula 162 is in fluid communication with port 164. Cannula 162 optionally includes a rubber valve providing a fluid seal between cannula 162 and hub 160. A removable cap 170 is adapted to cover first and second chamber 140, 142 to prevent fluid leakage therefrom (FIG. 13D). Cap 170 includes a first chamber cover 172, a second chamber cover 174 and a hinge 176 therebetween such that first chamber cover 172 and second chamber cover 174 can be opened and closed independently of each other. Cap 170 includes at least one finger grip 178 extending from the first and/or second chamber cover 172, 174. A cap extension 180 extends into and seals a slot that forms passageway 144. Cap 170 can be made from rubber or suitable plastic or elastomeric material as known in the art, such as for example, polypropylene, nylon, polyethylene or the like. It is envisioned that cap 170 can be formed as a separate component or can be formed monolithically with housing 138 using at least one living hinge therebetween, for example. In operation, the apparatus shown in FIGS. 13A-13D to collect umbilical cord blood is used by first placing a section of umbilical cord into first chamber 140. Collection tube holder can be installed in second chamber 142 before or after fluid is allowed to drain into second chamber. When fluid has drained into second chamber 142, port 164 of collection tube holder 150 extends into a pool of fluid. An evacuated tube 190 (FIG. 13C) having a rubber stopper 192 is placed over cannula 162 and pushed down onto cannula 162 to puncture rubber stopper 192 and provides a fluid passageway from second chamber 140 into the evacuated fluid collection tube 190. Vacuum pressure in evacuated tube 190 causes fluid to flow upward through port 164 and cannula 162 and into evacuated tube 190. When a sufficient fluid sample is collected into fluid collection tube 190, fluid collection tube 190 is removed from cannula 162. A rubber valve (not shown) may self seal around needle cannula 162 and rubber stopper 132 may self seal collection tube 130. Clinicians using the embodiment shown in FIGS. 13A-13D are thereby provided with an alternative method and apparatus according to the present disclosure for efficiently and safely collecting fluid samples such as umbilical cord blood while maintaining collected fluid, waste fluid and tissue in safely sealed containers which also provide protection from exposure to needle stick hazards. Although various embodiments of the present disclosure are described in terms of a two chamber apparatus, persons having ordinary skill in the art should appreciate that any number of chambers may be combined to provide a multi-chamber fluid collection apparatus according to the present disclosure. It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting but merely as exemplification of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. | <SOH> BACKGROUND <EOH>1. Technical Field The present disclosure generally relates to fluid collection apparatus, and more particularly, to an apparatus that facilitates fluid collection from an umbilical cord while preventing hazardous exposure to blood and body fluids collected. 2. Background of the Related Art Body fluids, such as blood, urine, etc., can be collected during various medical procedures for analysis. For example, fluid and blood samples are typically collected from an umbilical cord of a newborn infant to ascertain blood type and Rh factor. Collection of umbilical cord blood is also beneficial due to its considerable curative value, e.g., use in bone marrow replacement procedures for treatment of cancer and immuno-deficiency disorders. Further, fetal blood has important commercial and therapeutic use in medical fields, such as, tissue culture, stem cell collection, pharmacology and biological research. Several methods for umbilical cord blood sampling are known. One method includes holding a severed free end of an umbilical cord, still attached to a placenta, over a test tube or container. Blood is drained from the placenta into the test tube or container by milking the umbilical cord. A typical sample requires about 5 cc. This procedure has several disadvantages in that it is awkward to perform, difficult to control the sterility of the collected cord blood and may hazardously expose medical personnel to cord blood due to splattering, etc. In another method, blood is drawn from the umbilical cord vein via a large gauge needle and syringe. This procedure is also awkward to perform and may hazardously expose medical personnel to potential needle sticks. More recently, an umbilical cord segment is clamped on two ends and moved to a collection device or container where the cord blood is drained by removing the clamps from either or both ends. Ultimately, the cord blood must be transferred to a storage container, such as a test tube, to prevent contamination of the blood and minimize hazardous exposure to health care workers. These funnel type collection devices require larger apertures that interface with non-standard wide-mouthed test tubes because they rely on gravity to cause the blood to flow. Other cord blood collection devices include large containers to hold the entire cord segment. The containers are sealed so that vacuum pressure can be used to cause blood to flow through a smaller aperture or needle. Needle type interfaces, however, must include shielding to protect medical personnel. The necessary shielding adds more bulk to the collection device. The above devices disadvantageously expose medical personnel to accidental needle sticks and potentially hazardous body fluids. Needlesticks can, for example, occur during manipulation of a collection device including, assembly, dis-assembly or insertion into a blood vessel of the umbilical cord. Hazards such as, for example, needlesticks, splattering, etc. can present dangerous exposure to fluids contaminated with bacterial diseases, and potentially fatal viral infections such as AIDS, Hepatitis B and C, etc. Attempts have been made to overcome the disadvantages of the prior art and prevent hazardous exposure to blood and body fluids. Some designs employ a needle hood for a needle container which sealingly engages an evacuated tube. See, e.g., U.S. Pat. Nos. 5,915,384 and 5,342,328. Designs of this type, however, still involve the use of a container with a needle and may not adequately prevent hazardous exposure to blood and body fluids. Still other designs employ complicated valve connections between a container and a syringe for receiving collected cord blood. These prior designs, however, may not safely transfer fluid due to their complexity and number of parts. Complex structure can result in high manufacturing costs. Further, these configurations are not easily adapted to existing medical components. Consequently, there remains a need to provide a more satisfactory solution for fluid collection apparatus by overcoming the disadvantages and drawbacks of the prior art. Therefore, it would be desirable to provide a fluid collection apparatus for collection of umbilical cord fluid which prevents hazardous exposure to blood and body fluids and is adaptable to existing medical components. Such a fluid collection apparatus should have reduced complexity to increase reliability and improve fluid collection. It would be highly desirable for the fluid collection apparatus to employ luer connections thereby minimizing the potential for inadvertent needle stick. | <SOH> SUMMARY <EOH>Accordingly, the present disclosure addresses a need for a fluid collection apparatus which protects practitioners, supporting medical personnel and patients from hazardous exposure during umbilical cord fluid collection. The present disclosure resolves related disadvantages and drawbacks experienced in the prior art. More specifically, the apparatus and method of the present disclosure constitute an important advance in the art of fluid collection by providing an apparatus with reduced complexity and fewer needle interfaces. This structure advantageously improves safety and reliability while lowering manufacturing cost. Moreover, the apparatus does not require needle shields, etc. thereby reducing bulk. Desirably, the fluid collection apparatus employs luer connectors to avoid needle use and increase safety. In one particular embodiment, in accordance with the principles of the present disclosure, a fluid collection apparatus is provided. The fluid collection apparatus includes a housing configured for receipt of fluid and has a first surface which defines a needleless first mating portion. A holder has a first end and a second end configured to receive an evacuated tube. The first end defines a second mating portion on an outer surface thereof which is in fluid communication with the evacuated tube. The first mating portion sealingly engages the second mating portion to establish fluid communication therebetween. The housing may have a cylindrical body portion configured and dimensioned to support at least a portion of an umbilical cord. The first surface of the housing can have a funnel configuration. The first mating portion and the second mating portion may alternatively include a male connector and a female connector. Desirably, the first mating portion engages the second mating portion in a slip interference fit. In another embodiment, the first mating portion has a locking surface that engages the second mating portion to lock the housing with the holder. The housing can be releasably locked with the holder. The locking surface may have a threaded portion that receives the second mating portion. In yet another embodiment, the first end of the holder includes a needle hub supporting a needle cannula in fluid communication with the second mating portion and extending away from the first mating portion. The needle cannula may engage the evacuated tube to establish fluid communication between the first mating portion and the evacuated tube. In an alternate embodiment, an umbilical cord fluid collection apparatus includes a cylindrical housing defining a cavity for receipt of at least a portion of an umbilical cord. The housing has a funnel surface which defines a male luer connector. A holder has a first end and a second end configured to receive an evacuated tube. The first end defines a female luer connector on an outer surface thereof in fluid communication with an inner surface of the first end. The inner surface is in fluid communication with the evacuated tube. The male luer connector sealingly engages the female luer connector to establish fluid communication between the male luer connector and the evacuated tube. The configuration of the male luer connector of the housing advantageously facilitates adaptability to pre-existing holders having female luer connectors. The funnel surface may have a locking surface that engages the first end to lock the housing with the holder. The locking surface may be disposed about the male luer connector and includes a threaded portion that receives the first end of the holder. The inner surface of the first end can include a needle hub supporting a needle cannula in fluid communication with the female luer connector and extending away from the male luer connector. The needle cannula may engage the evacuated tube to establish fluid communication between the male luer connector and the evacuated tube. A method for collecting umbilical cord fluid is provided including the steps of: providing a fluid collection apparatus, similar to those described, attaching a first mating portion to a second mating portion to form a non-puncturing seal therebetween; disposing umbilical cord fluid in a housing; inserting an evacuated tube with a holder to establish fluid communication between the second mating portion and the evacuated tube such that umbilical cord fluid is collected in the evacuated tube. The step of providing may include an inner surface of a first end of the holder having a needle cannula extending away from the first mating portion such that the step of inserting includes puncturing the evacuated tube with the needle cannula to establish fluid communication between the second mating portion and the evacuated tube. Another particular embodiment of a fluid collection apparatus according to the present disclosure includes a support for standing the apparatus. As in the embodiments described above, a fluid collection apparatus includes a housing configured for receipt of fluid. The housing has a first surface which defines a needleless first mating portion. A holder having a first end and a second end is configured to receive an evacuated tube. The first end defines a second mating portion on an outer surface thereof which is in fluid communication with the evacuated tube. The first mating portion sealingly engages the second mating portion to establish fluid communication therebetween. A base disposed with the housing and being configured for support thereof. In the particular embodiment, the base has a top opening adapted for receiving the housing. The base is adapted for standing on a surface and is configured to enclose the holder. The housing can have a flange portion extending radially therefrom that engages the base. In at least one embodiment, the base defines at least one rib which forms a step for supporting the housing. Similarly, the base can define a plurality of ribs, each forming a step for supporting the housing. The base can also includes a plurality of sidewall extensions separated by cutout portions. In an illustrative embodiment according to the present disclosure, the base is configured to enclose the housing when the housing is fitted to a holder with an evacuated tube installed in the holder. Particular embodiments of apparatus according to the present disclosure also include a removable cap adapted to removably enclose an opening of the housing. The removable cap is adapted to provide a fluid seal with said housing. An illustrative embodiment of such a cap includes a finger grip or similar gripping portion to aid in removal from the opening of the housing. Another illustrative embodiment of the present disclosure includes a housing defining a cavity and being configured for receipt of fluid. A holder having a first end and a second end is configured to receive an evacuated tube. The first end includes a port that establishes fluid communication between the evacuated tube and the cavity of the housing. The port includes a needle cannula configured for disposal within the evacuated tube. The housing defines a well portion disposed adjacent the port of the holder. A bottom wall of the housing is sloped downward to define the well portion. A removable cap can be adapted to removably enclose an opening of the housing and provide a fluid seal with the housing. The removable cap can also include a plurality of snap arms adapted for engaging the housing. A base can be disposed with the housing and configured for support thereof. In still another embodiment of the present disclosure, a fluid collection apparatus includes a housing defining a first chamber. The housing is configured for receipt of fluid and a bottom wall of the housing has a sloped configuration. A holder defines a second chamber configured to receive a collection device having a port. The first chamber is in fluid communication with the second chamber via a passageway. A removable cap is adapted to removably enclose an opening of the housing and an opening of the holder. In a particular embodiment, the removable cap includes a first cover that encloses the opening of the housing and a second cover that encloses the opening of the holder. The first cover and the second cover can be hingedly connected, for example. In another particular embodiment, the housing and the holder are monolithically formed. | 20040325 | 20090915 | 20050113 | 63996.0 | 0 | CHAPMAN, GINGER T | BODY FLUID COLLECTION APPARATUS | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,810,255 | ACCEPTED | Electronic game table | The electronic game table of the invention may comprise a standard game table, e.g., for poker, incorporating multiple player seats for tournament or side game play. Each player has a display device in front of him/her containing information about the card in pocket. The community cards are displayed in the center of the table on a display device. Each player has a console with control elements, such as buttons, computer mouse, touch screen, etc. for activating means of betting, such as coins, tokens, credit or smart card readers, etc. A function of a dealer is accomplished by a central server, e.g., a random combination generator. For participation in multi table tournaments, e.g., of a poker game, the aforementioned electronic game table is provided with means of interfacing with other tables participating in the tournament via Internet, Intranet, local area network, etc., without participation of a live dealer. In fact, the players that are present at the same table have a feeling or participation in an actual card game since they see each other and may use such moves of a card game as bluffing, psychological interaction, etc. | 1. An electronic game table for at least two players comprising: table a frame; a plurality of individual player terminals arranged in said table with a terminal display and data input means; a central processing unit connected to each of said individual player terminals for bidirectional data exchange with each of said individual player terminals; and a common display in a position visible to said at least two players and connected to said central processing unit; said central processing unit containing a random combination generator. 2. The electronic game table of claim 1, wherein said central processing unit is provided with an outlet port for connection to external electronic means. 3. The electronic game table of claim 2, wherein said external electronic means are selected from the group consisting of a local area network, the Internet, and Intranet. 4. The electronic game table of claim 1, wherein said data input means comprises at least control means for anteing the bets, control means for betting, control means for indicating a role of a dealer in a current round. 5. The electronic game table of claim 4, wherein said position visible to said at least two players is a position selected from the group consisting from a position on said table top and outside said table top. 6. The electronic game table of claim 5, wherein said central processing unit is provided with an outlet port for connection to external electronic means. 7. The electronic game table of claim 6, wherein said external electronic means are selected from the group consisting of a local area network, the Internet, and Intranet. 8. The electronic game table of claim 1, which is a poker game table for a number of players from two to ten. 9. The electronic game table of claim 8, wherein said central processing unit is provided with an outlet port for connection to external electronic means. 10. The electronic game table of claim 8, wherein said external electronic means are selected from the group consisting of a local area network, the Internet, and Intranet. 11. The electronic game table of claim 8, wherein said data input means comprises at least control means for anteing the bets, control means for betting, control means for indicating a role of a dealer in a current round. 12. The electronic game table of claim 11, wherein said position visible to said at least two players is a position selected from the group consisting from a position on said table top and outside said table top. 13. The electronic game table of claim 12, wherein said central processing unit is provided with an outlet port for connection to external electronic means. 14. The electronic game table of claim 13, wherein said external electronic means are selected from the group consisting of a local area network, the Internet, and Intranet. | FIELD OF INVENTION The invention relates to table games, specifically to card game tables, in particular to the tournament type game tables, e.g., for playing poker or a similar multiplayer games. BACKGROUND TO THE INVENTION Table games are known to be a part of many societies. Generally, these games can be classified into two groups: ones incorporating interaction of an individual with a dealer (such are the majority of the casino games, e.g., blackjack or roulette) and the others, hereinafter referred to as tournament games, where a participant, which can be an individual or a team, competes only with another participant or team. Another important feature of the tournament games as opposed to casino games is participation of a human factor such as visual interaction between the players, as well as their mathematical and psychological strategies. In this case, the strategy might have the same influence on the outcome of the game as the initial random combination of factors such as a card combination in the hand of each player. For example, a poker player can “bluff” by betting he/she has the best hand when in fact he/she does not and may win by bluffing if players holding superior hands will not call his bet. Both mentioned types of the table games usually require the presence of a human operator, known as a dealer or croupier (hereinafter referred to as dealer). It should be noted that the role of such a dealer in casino games and tournament games is different. In the first case, a dealer may represent interests of the casino. For example, in a game of roulette the casino wins when the ball hits 0. In the second case, a random combination generator accomplishes the role of the dealer. In some game arrangements once in a game every player assumes the role of a dealer. Due to the requirement of the dealer having to maintain full control including supervising players, taking bets, determining the outcome of the game, calculating and paying winnings, collecting losses and all the while trying to be aware of any instances of cheating, the number of players per table has to be limited so as not to overtax the dealer. Accordingly, the overall profit of the casino or the club where the game takes place derived from the game is limited because the ratio between the dealer's salary and the income generated from the players is not high. In all the table games described above, all actions, including players betting, game outcome determination, calculation of winners and losers and subsequent settlement, are conducted manually. This presents a number of problems. Firstly, mistakes can be made by the player in placing a bet, resulting in an invalid bet, while mistakes may be made by the dealer in determining winners and more particularly, in calculating and paying out wins. Many attempts have been taken to automate the job of a dealer. One of the approaches is incorporation of the game machines, such as one disclosed in U.S. Pat. No. 6,695,695, issued in 2002 to Mark Angel. It discloses one of the variations of the electronic card game, in particular a variation of the game known as “video poker”. This video-implemented casino card game deals multiple hands. In a preferred embodiment it includes means for simulating a plurality of players on a game display. Each simulated player is dealt a hand of cards pursuant to a predetermined card game selected by a game player. Subsequent to the initial deal, the game player selects which hand to play. Once the hand has been selected, each hand is fully played. Only the game player's hand is fully revealed during play. Based on the game player's final cards, the player is paid according to a pay table. Thereafter, all hands are revealed and the game player is paid a bonus amount if the player's selected hand is the highest hand of the dealt hands. In a card game requiring a draw, or decision, unselected card hands are played according to a preprogrammed methodology within a gaming machine's internal microprocessor. Such a game replaces a dealer with a random (in reality—pseudo-random) sequence generator; however, being individual by nature it does not allow real interaction between the physical players and therefore cannot be used for the tournaments. All the participants of such a video game but one are simulated by a computer and all the psychological strategic parts of the game that constitute an important element of, i.e. poker, is eliminated since there is no human-to-human interaction. U.S. Pat. No. 6,659,866, issued in 2003 to B. Frost et al. discloses an automated game table, in the preferred embodiment described as a table for roulette. In this apparatus, physical persons that participate in the game are provided with an electronic interface through which the players interact with a dealer. Such a table allows a multiple player arrangement, where the players place bets, and wins or losses are calculated using electronic means, while the game itself is conducted using traditional, manual systems operated by a dealer. The problem of such an arrangement is that despite the dealer need not watch for irregularities or calculate wins and losses, he/she still needs to physically conduct the game elements—for example, spinning a roulette wheel or tossing the cards. Since the electronic table of the last-mentioned type incorporates a live dealer as an indispensable participant of the game, such table is inconvenient for use in multiple-table tournament games, e.g. poker, where there is no necessity to incorporate the actions of the dealer. More over, participation of several dealers (e.g., one per table) or of a common dealer for a plurality of tables, will impart additional complexity to the game and may lead to human errors. OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention is to provide an electronic table for games with multiple participants without the presence of the dealer. Another object is to provide a tournament game table wherein the players play without participation of a dealer and where the players may visually and psychologically interact with each other. Still another object is to provide the electronic game table provided with means for combining a plurality of such tables into a multiple table tournament via Internet or a local area network without participation of a live dealer or dealers. Still another object is to provide the electronic table for the game of poker with a virtual dealer. The electronic game table of the invention may comprise a standard game table, e.g., for poker, incorporating multiple player seats for tournament or side game play. Each player has a display device in front of him/her containing information about the card in pocket. The community cards are displayed in the center of the table on a display device. Each player has a console with control elements, such as buttons, computer mouse, touch screen, etc. for activating means of betting, such as coins, tokens, credit or smart card readers, etc. A function of a dealer is accomplished by a central server, e.g., a random combination generator. For participation in multi table tournaments, e.g., of a poker game, the aforementioned electronic game table is provided with means of interfacing with other tables participating in the tournament via Internet, Intranet, local area network, etc., without participation of a live dealer. In fact, the players that are present at the same table have a feeling or participation in an actual card game since they see each other and may use such moves of a card game as bluffing, psychological interaction, or advantageous use of mistakes made by other participants. In the case of a multiple-table tournament, the servers of the individual tables can be connected with an external CPU that may use, e.g., a master-slave protocol or any other type of data exchange. DETAILED DESCRIPTION OF THE INVENTION Although it is known that the proposed configuration can be used for different games such as dice, dominoes and miscellaneous card games, for the preferred embodiment we will describe an electronic tournament poker table. It will be beneficial for clarification of the scope of the embodiment if we will provide a brief overview of the rules of poker. More detailed description can be found in the vol. 18 of Encyclopaedia Britannica (p. 108 of the 1966 edition). There are forms of poker suitable to any number of players, but in most forms the ideal number is six to ten players. Poker is almost always played with the standard fifty-two-card deck with cards of each of the four suits (clubs, spades, diamonds, hearts) ranking downward from the Ace to the Two (in some combinations Ace is the low card). In addition to these cards the Wild Cards or “freaks” are introduced into the deck in some versions of the game. These terms are used to denominate an additional card, which stands for any other card its holder wishes to name (i.e. Joker). The object of the game is to win the “pot” which is the aggregate of all bets made by all players in anyone deal. The pot may be won either by having the highest-ranking hand or by making a bet no other player calls. “Hands” are the combinations generally of five cards, its value being inverse proportion to its mathematical frequency; that is the more unusual the combination of the cards, the higher the hand ranks. Further on, there is the number of varieties of the game different by the rotation, betting procedure or betting limits. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an electronic game table according to one embodiment of the invention. FIG. 2 shows one of the variations of the player console on the table of FIG. 1. FIG. 3 is a block diagram of the electronic units of the game table of the invention. FIG. 4 shows a system for multi-table tournament on the basis of the electronic tables of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT An electronic card game table of the present invention is shown in FIG. 1, which is a three-dimensional view of the table. The electronic card game table, which hereinafter will be referred to as a game table is designated as a whole by reference numeral 10. In its dimensions and shape the game table 10 corresponds to a conventional or standard card game table, e.g., the one installed in clubs or casinos for playing a poker game. In other words, the table 10 has a frame that may consist of a tabletop 10a and a supporting frame or base 10b. The table top 10a may have horizontal or vertical orientation. For example, the game table 10 may have a horizontal tabletop and be designated for 6 to 10 players and may have the following dimensions: 82″×42″. Although the minimum number of players may be 2 and the maximum number of players may be “n”, the embodiment of the game table 10 shown in FIG. 1 is designed for 10 players. Each players sits in front of one of terminals 121, . . . 1210 so that they can observe all other players in order to have feel of a real game where they can bluff or use other psychological moves of a real game. Each player is provided with a player interface console 141, . . . , 1410. One of possible layouts of the player interface console is considered in more detail below. The game table 10 is equipped with a common display 16 of community cards and is located in a place clearly visible for all the players. For example, a common display 16 may be located in the center of the table (as shown in FIG. 1) or on a remote hanging display panel (not shown). The game table 10 is also provided with a table CPU 17 which is connected to all the player interface consoles 141, . . . , 1410 and has means, such as a standard or wireless port 18 for connection to other remote CPU's that may be used, e.g., for the multi-table arrangement in the case of a tournament. To assure that the cards in every pocket and financial activities of the players are kept in privacy, player interfaces can be separated by partitions or hidden in recesses 221, . . . , 2210. As shown in FIG. 2, each of the user terminals 121, . . . , 1210 consists of a display 32, a button 34 indicating a player assuming a role of a dealer in the current round (here we have to remind that the dealer role is absolutely virtual and is introduced only to assure the game flow, not to actually deal the cards), player in and out indicators 36 and 38, bet operation buttons 401, 402, and 403, action buttons 41-1, . . . , 41-n and means of payment (currency, credit or smart card reader) 43. FIG. 3 is a block diagram of the electronic units of the game table of the invention. As can be seen from this drawing, the CPU 17 contains random combination generator unit 19 which in the electronic table 10 of the invention plays a role of a principal dealer who is absent from the game as a physical person. In this connection it should be noted that not only the physical dealer but also a physical stack of card is also absent in the game. Therefore, whenever dealing the card is mentioned, it is assumed that appropriate card are seen on the screen of the appropriate displays. Each user terminal 121, . . . , 1210 is linked to the common CPU 17 via respective links 131, 132, . . . , 1310. Furthermore, the CPU 17 is linked via a link 15cpu with the common display 16. As is known, there exists a number of varieties of the poker games different by the rotation, betting procedure or betting limits. Such varieties of the poker game are known as Seven Card Stud, Omaha Hi Lo, Texas Hold'em, etc. The rules and strategy of these games are beyond the scope of the present invention. In order to illustrate the use of the game table 10 of the present invention, let us assume that 4 players participate in a $2/$4 s. Seven Card Stud game. First, all the players have occupied their positions at appropriate consoles, e.g., 121, 122, 124, 125. The tournament begins when all the seats are occupied, and funds are deposited using the credit card reader 43. According to the rule of poker, the deposits may be displayed to other players. This information can be shown either on the displays 32 or on the common display 16. After this moment, none of the players can change the seat. In order to determine who deals the first round, each player is dealt one card randomly through the action of the random combination generator unit 19. This is done by pushing on the appropriate action button, e.g., button 41-1. Let us assume that the play who gets the lowest card. This fact is indicated by this player pushing the button 34 indicating the player assuming a role of a dealer in the current round. The cards are returned to the stack by pushing an appropriate action button, e.g., button 44-2. The player who assumes a role of the dealer deals each player two cards face down and one face up, which can be done via the CPU17 by pushing one of the action buttons. Let us assume that all the players have anted $0.50. Betting is accomplished by pushing one of the bet operation buttons 401, 402, or 403. The player with the lowest up card makes a forced bet of either $1 half minimum bet or $2 full bet (player's choice) to start the game. The rest of the players, in clockwise order, either call the opening bet, raise it, using another bet operation button, or not call and “fold” their hands back to the dealer. All get a fourth card face up followed by a round of $2 betting. From this round on, the player with the highest up card(s) is always first to check or bet. After the fifth card is dealt face up, the minimum bet goes to $4. The sixth card is dealt face up and there is another round of $4 betting. The seventh and last card is dealt face down and followed by the final round of $4 betting. All aforementioned operations, associated with pushes on any action or bet operation buttons at all the consoles are registered and stored in the CPU 17 via respective connection links 131, 132, . . . , 1310. The CPU 17 analyzes the players' inputs and determines and awards the pot. FIG. 4 illustrate an arrangement for a multi-table tournament in which several electronic game tables 110 and 112, such as the table 10 (FIG. 10) can be combined into a system in which CPU's 117 and 119 of individual tables are connected to each other and to a common multi-table display 116. This can be done via standard or wireless port 18 (FIGS. 1 and 4). Thus, it has been shown that the present invention provides an electronic table for games with multiple participants without the presence of a common dealer, where the players may visually and psychologically interact with each other. The invention provides a table having a standard or wireless port for combining several tables into a system of a multi-table tournament. Although the invention has been shown and described with reference to specific embodiments, it is understood that these embodiments should not be construed as limiting the areas of application of the invention and that any changes and modifications are possible, provided these changes and modifications do not depart from the scope of the attached patent claims. For example, the electronic game table of the invention may be designed for any number of participants that is equal or greater than 2. The table may have any shape, e.g., a circular or semicircular shape. The individual player terminals can be located on the bottoms of the hidden recesses made in the surface of the table top. The table is intended for a great variety of tournament games without limitation to the card games or to specific card games. For example the table can be used for playing dominoes, dice, etc. The outlet port of the table's CPU can be used for connection to a local area network or to Internet, Intranet, etc. | <SOH> BACKGROUND TO THE INVENTION <EOH>Table games are known to be a part of many societies. Generally, these games can be classified into two groups: ones incorporating interaction of an individual with a dealer (such are the majority of the casino games, e.g., blackjack or roulette) and the others, hereinafter referred to as tournament games, where a participant, which can be an individual or a team, competes only with another participant or team. Another important feature of the tournament games as opposed to casino games is participation of a human factor such as visual interaction between the players, as well as their mathematical and psychological strategies. In this case, the strategy might have the same influence on the outcome of the game as the initial random combination of factors such as a card combination in the hand of each player. For example, a poker player can “bluff” by betting he/she has the best hand when in fact he/she does not and may win by bluffing if players holding superior hands will not call his bet. Both mentioned types of the table games usually require the presence of a human operator, known as a dealer or croupier (hereinafter referred to as dealer). It should be noted that the role of such a dealer in casino games and tournament games is different. In the first case, a dealer may represent interests of the casino. For example, in a game of roulette the casino wins when the ball hits 0. In the second case, a random combination generator accomplishes the role of the dealer. In some game arrangements once in a game every player assumes the role of a dealer. Due to the requirement of the dealer having to maintain full control including supervising players, taking bets, determining the outcome of the game, calculating and paying winnings, collecting losses and all the while trying to be aware of any instances of cheating, the number of players per table has to be limited so as not to overtax the dealer. Accordingly, the overall profit of the casino or the club where the game takes place derived from the game is limited because the ratio between the dealer's salary and the income generated from the players is not high. In all the table games described above, all actions, including players betting, game outcome determination, calculation of winners and losers and subsequent settlement, are conducted manually. This presents a number of problems. Firstly, mistakes can be made by the player in placing a bet, resulting in an invalid bet, while mistakes may be made by the dealer in determining winners and more particularly, in calculating and paying out wins. Many attempts have been taken to automate the job of a dealer. One of the approaches is incorporation of the game machines, such as one disclosed in U.S. Pat. No. 6,695,695, issued in 2002 to Mark Angel. It discloses one of the variations of the electronic card game, in particular a variation of the game known as “video poker”. This video-implemented casino card game deals multiple hands. In a preferred embodiment it includes means for simulating a plurality of players on a game display. Each simulated player is dealt a hand of cards pursuant to a predetermined card game selected by a game player. Subsequent to the initial deal, the game player selects which hand to play. Once the hand has been selected, each hand is fully played. Only the game player's hand is fully revealed during play. Based on the game player's final cards, the player is paid according to a pay table. Thereafter, all hands are revealed and the game player is paid a bonus amount if the player's selected hand is the highest hand of the dealt hands. In a card game requiring a draw, or decision, unselected card hands are played according to a preprogrammed methodology within a gaming machine's internal microprocessor. Such a game replaces a dealer with a random (in reality—pseudo-random) sequence generator; however, being individual by nature it does not allow real interaction between the physical players and therefore cannot be used for the tournaments. All the participants of such a video game but one are simulated by a computer and all the psychological strategic parts of the game that constitute an important element of, i.e. poker, is eliminated since there is no human-to-human interaction. U.S. Pat. No. 6,659,866, issued in 2003 to B. Frost et al. discloses an automated game table, in the preferred embodiment described as a table for roulette. In this apparatus, physical persons that participate in the game are provided with an electronic interface through which the players interact with a dealer. Such a table allows a multiple player arrangement, where the players place bets, and wins or losses are calculated using electronic means, while the game itself is conducted using traditional, manual systems operated by a dealer. The problem of such an arrangement is that despite the dealer need not watch for irregularities or calculate wins and losses, he/she still needs to physically conduct the game elements—for example, spinning a roulette wheel or tossing the cards. Since the electronic table of the last-mentioned type incorporates a live dealer as an indispensable participant of the game, such table is inconvenient for use in multiple-table tournament games, e.g. poker, where there is no necessity to incorporate the actions of the dealer. More over, participation of several dealers (e.g., one per table) or of a common dealer for a plurality of tables, will impart additional complexity to the game and may lead to human errors. | <SOH> OBJECTS AND SUMMARY OF THE INVENTION <EOH>It is an object of the present invention is to provide an electronic table for games with multiple participants without the presence of the dealer. Another object is to provide a tournament game table wherein the players play without participation of a dealer and where the players may visually and psychologically interact with each other. Still another object is to provide the electronic game table provided with means for combining a plurality of such tables into a multiple table tournament via Internet or a local area network without participation of a live dealer or dealers. Still another object is to provide the electronic table for the game of poker with a virtual dealer. The electronic game table of the invention may comprise a standard game table, e.g., for poker, incorporating multiple player seats for tournament or side game play. Each player has a display device in front of him/her containing information about the card in pocket. The community cards are displayed in the center of the table on a display device. Each player has a console with control elements, such as buttons, computer mouse, touch screen, etc. for activating means of betting, such as coins, tokens, credit or smart card readers, etc. A function of a dealer is accomplished by a central server, e.g., a random combination generator. For participation in multi table tournaments, e.g., of a poker game, the aforementioned electronic game table is provided with means of interfacing with other tables participating in the tournament via Internet, Intranet, local area network, etc., without participation of a live dealer. In fact, the players that are present at the same table have a feeling or participation in an actual card game since they see each other and may use such moves of a card game as bluffing, psychological interaction, or advantageous use of mistakes made by other participants. In the case of a multiple-table tournament, the servers of the individual tables can be connected with an external CPU that may use, e.g., a master-slave protocol or any other type of data exchange. | 20040329 | 20071211 | 20050929 | 73692.0 | 1 | NGUYEN, KIM T | ELECTRONIC GAME TABLE | SMALL | 0 | ACCEPTED | 2,004 |
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10,810,361 | ACCEPTED | Fast swapping station for wafer transport | An apparatus for accepting and transferring at least one disk-like member is provided. The apparatus includes a pick- and place-mechanism including gripping means. In effect, the mechanism is adapted to provide pick- and/or place-cycles, which during operation provides a movement of said gripping means between an up and a down position and vice versa, whereby, in the down position, said gripping means either picks the disk-like member from a load position or places the disk-like member onto the load position. | 1. An apparatus for swapping a disk-like member, said apparatus comprising: at least two tong-like arms for accepting and holding the disk-like member; and a driving-mechanism adapted to drive said at least two tong-like arms, wherein said driving-mechanism is adapted to provide a first movement and a second movement to said at least two tong-like arms, said first movement comprising a vertically oriented movement of said at least two tong-like arms between an up position and a down position, said second movement comprising a horizontally oriented tong-like movement of said at least two tong-like arms. 2. The apparatus according to claim 1, wherein said driving-mechanism comprises a lever apparatus and/or spindle means for controlling said first and second movements. 3. The apparatus according to claim 1, wherein said driving-mechanism, when performing said second movement, moves said at least two tong-like arms between at least one hold position and at least one release position. 4. The apparatus according to claim 3, wherein said driving-mechanism moves said at least one hold position is two different hold positions and said at least one release position is two different hold positions. 5. The apparatus according to claim 1, wherein said driving-mechanism comprises an elevation contrivance and a manipulator drive. 6. The apparatus according to claim 1, wherein said at least two tong-like arms comprise extension members. 7. The apparatus according to claim 1, wherein said at least two tong-like arms comprise means for gripping the disk-like member. 8. The apparatus according to claim 7, wherein said gripping means comprises at least one grooved circular ring section adapted to a dimension of the disk-like member. 9. The apparatus according to claim 1, further comprising a housing including at least a part of said driving-mechanism. 10. The apparatus according to claim 1, wherein said at least two tong-like arms comprise a tong-like structure which enables the arms to be front-loaded or back-loaded. 11. The apparatus according to claim 1, wherein said driving-mechanism comprises at least one driving motor. 12. The apparatus according to claim 1, wherein said at least two tong-like arms are affixed to said driving-mechanism. 13. The apparatus according to claim 1, further comprising means for detecting the disk-like member and/or for detecting a position of said at least two tong-like arms. 14. The apparatus according to claim 1, further comprising means for controlling movement of said at least two tong-like arms. 15. A method for handling or transporting disk-like members, comprising: transporting a first disk-like member with a first transporter from a first position to an exchange region; loading said first disk-like member into exchange region; transporting a second disk-like member with second transporter to said exchange region; loading said second disk-like member from said second transporter to said first transporter; transferring said first disk-like member from said exchange region to said second transporter; and transporting said first disk-like member to a second position with said second transporter. 16. A handling line for handling disk-like members, comprising: a disk-like member exchange region; a first transporter having a first set of arms; a first driving-mechanism adapted to drive said first set arms, said first driving-mechanism providing said first set of arms with a first movement and a second movement, said first movement comprising a vertically oriented movement and said second movement comprising a horizontally oriented tong-like movement; a second transporter having a second set of arms; a second driving-mechanism adapted to drive said second set arms, said second driving-mechanism providing said second set of arms with said first movement and said second movement; and a controller for controlling said first transporter to move through said first and second movements so that a first disk-like member is transferred to said exchange region, and said second transporter to move through said first and second movements so that a second disk-like member is transferred to said first transporter at said exchange region. 17. The handling line according to claim 16, wherein said first transporter and/or said second transporter comprises a device selected from the group consisting of an x-y-stage, a chuck, and a robot. 18. The handling line according to claim 16, wherein said controller controls said second transporter to transfer said first disk-like member from said exchange region to said second transporter. 19. The handling line according to claim 18, wherein said controller controls said second transporter to move said first disk-like member to a second position. | BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an apparatus for swapping at least one disk-like member, a method for transporting wafers, and a handling line for carrying out the method for transporting wafers. 2. Description of Related Art Apparatus for accepting and transferring wafers are well known in the art. For instance, robot handlers are commonly used to move materials, e.g. semiconductor wafers, between different stages of a wafer fabrication process. In this regard, robot handlers might be used to move the wafer from a plasma etch station in a cluster tool to a deposition station or from a manufacturing station to a testing station or metrology tool, wherein the wafer is positioned onto a chuck. In this kind of handling system the throughput depends strongly on the time the metrology tool has to wait for material handed over by the robot handler. A typical transporting or handling scenario for a wafer handling system is the following: a) the handling system, typically a one-arm-robot-handler gets a new wafer, b) the handling system moves and loads the wafer onto the transfer position for transferring the wafer for example into the metrology tool, c) the wafer gets moved into the tool for processing or measuring; after this the wafer gets back to the transfer position or unload position which is typically the same as the load position, d) the handling system, i.e. the robot handler, picks the wafer and unloads the wafer to the next position, The cycle starts from step a) During the processing of the wafer in the metrology tool the handling system or robot waits or is doing different tasks. But for doing different tasks the handling system has to do motions without wafer. This however is ineffective and forms a bottleneck of the transport system, which limits the throughput. The problem might be solved by employing a so-called dual-arm or paddle-robot that can handle two wafers at the same time. However, such a handling system has a increased footprint, since the arms increase the sweep radius of the robot, which is caused by the space that is needed horizontally to swap the wafer at the desired station. Yet, space in a clean room environment, which is commonly needed for wafer production, is a scarce resource. Therefore, an increase in food print of the handling system would raise production costs considerably. Moreover these kind of robots are more complex in handling and their purchase price is high. Therefore, a solution is needed which on the one side increases the throughput and on the other minimizes the space consumption and the additional footprint, respectively, needed. These and other disadvantages have lead to the object of the present invention to provide an apparatus as a part of a handling system which avoids to use complex handling systems with a big footprint but nevertheless can increases the throughput considerably. SUMMARY OF THE INVENTION The inventive solution is obtained by the provision of an apparatus for swapping at least one disk-like member, e.g. a wafer. The apparatus includes at least two tong-like arms for accepting and holding the disk-like member and a driving-mechanism adapted to drive the arms. The mechanism is adapted to provide a first and a second movement of the arms, whereby the first movement is a vertically oriented movement of the arms and the second movement is a horizontally oriented tong-like movement of the arms. Thus far, in general, the invention is an apparatus for swapping at least one disk-like member, e.g. a wafer, the apparatus comprises at least two tong-like arms for accepting and holding the disk-like member and a driving-mechanism adapted to drive the arms, wherein the mechanism is adapted to provide a first and a second movement of the arms, whereby the first movement comprises a vertically oriented movement of the arms from an up to a down position and vice versa, and whereby the second movement comprises a horizontally oriented tong-like movement of the arms. The inventive apparatus, for example, can be advantageously simply arranged in-line or in series to an one arm handling system and a load position of, for instance, a chuck of a motion system which transfers a disk-like member or a wafer, e.g. into a testing station. In this regard the inventive apparatus is able to accept, hold or store the disk-like member with its tong-like arms, being driven by the driving mechanism, from the handling system, whereby, after having placed the disk-like member or wafer into the arms of the inventive apparatus, the unloaded handling system can pick another wafer from, for instance the chuck, coming out of the testing station. If these steps are completed, the inventive apparatus is highly advantageous able to transfer or place or swap the stored wafer with its tong-like arms on the load position or chuck to be transferred into the testing station. Of course, the just described cycle works also the other way round. Thus, any motion of the handling system without wafer can be avoided if the inventive apparatus is applied. It should be emphasis that according to the invention the term disk-like member, in its meaning, comprises any kind of member which can be swapped or transferred by means of the inventive apparatus, or which is adapted to be used within the inventive process. Thus, in the inventive sense disk-like members can be, for instance, round like a wafer, or rectangular like a plate, or can be of any appropriate shape. With regard to an advantageous further development of the inventive apparatus a lever apparatus and/or spindle means is provided which controls or governs the movement of the tong-like arms. Thus, the lever apparatus and/or spindle means together with the inventive driving mechanism, at least guarantees a movement of the tong-like arms into one hold and into one release position and vice versa. The hold position is characterized by the fact that in this position the arms are ready to accept and/or to hold a disk-like member or wafer, whereas in the release position the arms are opened such that a disk-like member can be charged or discharge by the arms. Thereby, it is guaranteed that especially in the case when the arms charge or grip a disk-like member or wafer the distance between the arms and the arms and the dislike member, respectively, is such that there will be no damage of the disk-like member. According to an additional advantageous further development of the inventive apparatus the driving mechanism is separated into an elevation contrivance and a manipulator drive. The manipulator drive causes the arms to perform a tong-like move in a plan, whereas the elevation contrivance preferably moves the arms and/or the manipulator up and down, i.e. in a direction preferably perpendicular to the plan defined by the tong-like movement of the arms. Advantageously, both movements, and thus both apparatus can be controlled independently. Yet, with regard to another preferred embodiment of the invention, it is provided that the driving mechanism or the manipulator drive comprises the functionality to move the arms into two different hold positions and into two release positions corresponding to the hold positions. This kind of functionality gives the possibility to use the inventive apparatus for different kind of disk-like members, e.g. for wafer with different diameters. So far, the inventive apparatus might be for example used for wafer seizes with a diameter of 200 mm or of 300 mm. In connection with this, the invention also provides extension members that are part of the arms, and which advantageously allow to flexible adjust the feed opening or the distance between the arms. This opens up the possibility to use the inventive apparatus for swapping disks with not only two or three different diameters but with all kind of diameters. Another structural element of the invention which positively further develops the inventive apparatus is given if the apparatus comprises gripping means which helps the arms to grip the disk-like member. The gripping means contacts the edges of the disk-like member, when it is held or gripped by the inventive apparatus or tong-like arms. For that purpose, advantageously the gripping means comprises at least one grooved circular ring section, which is adapted to the radius or diameter of the wafer to be gripped. For to provide a compact assembly the inventive apparatus comprises a housing, wherein at least a part of the driving mechanism for the tong-like arms is accommodated. Thereby openings are provided through which the arms extend for to grip the disk-like member. Advantageously, moreover, it is given that the arms are formed in a way that enables the apparatus and the arms respectively to be front- or to be back-loaded. Front-side in this respect is the side to which the arms extend to, and back side is the side in opposition to the front-side. According to another further development of invention the inventive apparatus or driving mechanism comprises at least one driving motor, which one the one side drives the vertical movement of the tong-like arms via the lever apparatus and/or spindle and which on the other side also drives the horizontal movement of the arms. Highly advantageously, according to the invention, the inventive apparatus also comprises sensor means for detecting the disk-like member, i.e. for to tell the apparatus whether there is a disk-like member or not inside the inventive apparatus and/or for detecting the position of the tong-like arms. For the latter purpose sensors, for instance, can be arranged in pairs with respect to the arms such that they are able to indicate at least two different relative positions of the arms to each other. In this respect, one of the sensor, for example, could indicate the hold position of the respective arm and the other the release position of the respective arm. The same applies if the inventive apparatus is dimensioned for disk-like members of different diameter, whereby for each disk-like member a hold and a release position can be defined via the arrangement of sensors or via sensor readings. Moreover, sensors could be provided which indicate the height of the arms with respect to a defined level. According another aspect of the invention the inventive apparatus favorably comprises or is connectable to control means for controlling the movement of the arms and/or motor drives etc. For that purpose appropriated interfaces and at least one micro-controller are/is provided. Additionally to the above stated, it is a further object of the present invention to provide a method which by use of the inventive apparatus avoids to use complex handling systems but nevertheless increases the throughput considerably. Therein a method for handling or transporting disk-like members, e.g. wafers, is defined, wherein an apparatus as described above is positioned into an exchange-region for exchanging dislike-members, for that purpose a first disk-like member with first transport means from a first position is transported to the exchange region, at the exchange region the first disk-like member is loaded into the inventive apparatus, after or parallel to the latter load or even before the latter load a second disk-like member with second transport means is transported to the exchange region, the second disk-like member, after having unloaded the first transport means, the second disk-like member is loaded from the second transport means to the first transport means, and after having unloaded the second transport means, the first disk-like member gripped, loaded or charged by the inventive apparatus is transferred from the inventive apparatus to the second transport means, if this is done the second disk-like member can be transported to a second position by means of the second transport means. The cycle can start again. An even further object of the invention is to provide a handling line to accomplish the just described method. The inventive handling line comprises respective means for carrying out the method. Thus, in particular, it might comprises a x-y-stage or a chuck and/or a robot to replace either the first or the second transport means. BRIEF DESCRIPTION OF THE DRAWING The invention together with additional features and additional advantageous thereof will be best understood from the following description. It is shown: FIG. 1 a cross-sectional view of one embodiment of an apparatus according to the invention wherein the tong-like arms are in the up position, FIG. 2 the cross-section as shown in FIG. 1, wherein the tong-like arms are in the down position, FIG. 3 a bottom view FIG. 1 including the wafer the arms and the grippers of the arms, FIG. 4 a cam disk top view with two cam rings, FIG. 5 a topography or profile of the cam rings of the cam disk according to FIG. 6 FIG. 6 a place cycle of the arms, FIG. 7 a moving flow chart of the arms, FIG. 8 a perspective view of the front side of another embodiment according to the invention, FIG. 9 a perspective view of the back side of the embodiment of FIG. 8, FIG. 10 a schematic top view of the manipulator drive together with the tong-like arms of FIG. 8 except that the manipulator drive just comprises one actuator for driving the lead screws and the tong-like arms respectively, FIG. 11 a schematic top view as shown in FIG. 10 except that the manipulator drive comprises a manipulator-belt-drive assembly for driving the lead screws and the tong-like arms respectively, FIG. 12 a schematic top view of another embodiment of the manipulator drive and the tong-like arms of an inventive swapping apparatus, wherein the manipulator drive comprises a gear drive and lever apparatus for driving the tong-like arms. FIG. 13 the handling process if an apparatus according to the invention is used, in case the inventive apparatus is first front-loaded, FIG. 14 the handling process or FIG. 8 with the difference that the inventive apparatus is first back-loaded. DETAILED DESCRIPTION FIGS. 1 and 2 are showing a design of the inventive apparatus generally referred to hereinafter to be a Fast swapping station (FSS-1). The inventive fast swapping station comprises a driving mechanism 100 and tong-like arms 107a and 107b. The propulsive power of driving mechanism 100 is provided by motor 101. The motor 101, which is fixed to the top part of the housing 102 is mounted in the center of the housing 102 of the driving mechanism 100 and rotates the cam plate 104. The housing 102 has a cylinder box structure with openings 102a and 102b in its cylinder-jacket, whereby the openings 102a and 102b are arranged opposed to each other. The driving axis 101a of the motor 101 is fixed in the mounting hole 104c of the plate 104. The disk or plate 104 has two higher circles or rings 104a and 104b with a changing topography in height which reflects the cam structures 103a and 103b on the disk 104 (see also FIG. 4). The rotating plate 104 and the driving axis 101a are supported by the bearing 105 at the center of the lower part or bottom side of the housing 102. In side the housing, centrally arranged, a space 112 is provided which accommodates the motor 101. The space is formed by a wall 113 surrounding the motor and is adapted to the geometry of the motor, e.g. cylindrical, together with the upper part or top surface of the housing 102, to which the wall 113 is integrally attached to, and from which it extends down to the bottom of the housing and the plate 104. The wall 113, being in touch with the motor 101 at its inner side, is the inner part of a sliding bearing 106 at its outside. The counter or outer part of this sliding bearing 106 is the inside of an opening of the support structure 110 (110a and 10b) which is riding with two rollers 117a and 117b on the inner circle 104b with the cam structure or contour profile 103b. This support structure 110 holds two arms 107a and 107b. The arms 107a and 107b are rectangular in shape and comprise two legs 115a, 115b and 116a, 116b each, namely upper legs 115a and 116a and side legs 115b and 116b. For the sake of simplicity the structure and function of only one of the arms 107a and 107b is described further, whereby the arms 107a and 107b are in structure and functionality the same except that they are arranged in opposition or mirror relationship to each other. The upper leg 115a of the arm 107a has been inserted into or extends through the opening 102a of the housing 102, and is moveably attached to the fulcrum 114a of holding arm 110a of the support structure 110 to form a lever apparatus, which allows the upper leg 115a under defined circumstance, which will be described hereinafter, to change its angle with respect to the horizontal line and the holding arm 110a respectively. The upper leg 115a with its end inside of the FSS-1 housing 102 has a roller 108a rotatably fixed at its end, whereby the roller 108a is supported by the second topography 103a of the rotating plate 104. The upper leg 115a, and thus the support structure arm 110a too, is held down or pushed against to the contour circles 104a or cam structure 103a with the spring 109a. For this purpose the spring 109a is fixed to the upper leg 116a and the bottom part of the housing 102 at a point between the roller 108a and the bearing fulcrum 114a depending on the force to be excerpted on to the upper leg 115a and the contour profile 103a, respectively. Thus, by rotating the plate 104 the rollers 117a and 117b of the support structure 110 will follow the topography of the cam structure 103b, and the rollers 108a and 108b of the arms 107a and 107b will follow the topography of the cam structure 103a, whereby the arms 107a, 107b perform a tong-like movement. It is the difference between the two profiles of the two cam structures 103a and 103b that causes a change in the relative position between the support structure 110 and the arms 107 (107a and 107b). In this regard FIG. 1 shows the support structure 110 to be pushed up upon rotation of plate 104, and the arms with their upper legs 115a and 116a are pushed up to the same height as well. This is the situation in which the arms can hold a wafer 118 or, in case there is no wafer, can accept or store a wafer from a robot handler of a wafer handling system. FIG. 2 shows the support structure down upon rotation of the plate 104, and the arms support 103a is even more down, because at the angular position of plate 104, shown in FIG. 2, the rollers 108a and 108b of the arms 107a and 107b, respectively, are pushed down to a lower height than that of rollers 117a and 117b which results in a counter clockwise movement of the arm 107b and a clockwise movement of the arm 107a, up to a defined angle, that depends on the cam structure differences in height at the down position, whereby the side legs 115b and 116b are pushed aside like the arms of a tongs. In this case the arms 107 (107a and 107b) are opened in a down position to release the wafer 118 to a chuck 120 or to accept the wafer 118 from the chuck 120. The grippers or retaining zones 119 (119a and 119b) of the arms for to hold the wafer consists of two circular ring or rim sections 119a and 119b, which radius is adapted to that of the wafer (FIG. 3). In the cross-sectional view of FIG. 1 or 2 it can be seen that the ring sections 119a, 119b comprise retaining grooves, whereby the cross-section of the grooves deviates slightly from a “L”. In this respect, the vertical part makes an angle with the lower part which is bigger than 90°. Thus, the wafer can be easily gripped into the retaining zone 119 without pinching and damaging it. In the hold position of the arms 107 the wafer sits on the lower part of the groove and the vertical part or raising edge of the groove keeps the wafer 118 at a defined position, i.e. radius, during motion. This can be even better seen in FIG. 3. Therein the dashed lines mark the end of the grippers or retaining zones. The gripping mechanism of the FSS-1 is the like that the arms 107 open wide enough and closes slowly enough that when the arms 107a and 107b are pushed upwards to the up or hold postion, whereby the grippers 119 pass the wafer without touching it on its way up. In order to achieve this motion a profile or cam structure 103a and 103b of the contour is provided as shown in FIG. 5. FIG. 5 displays in part a projection of the cam 103a and 103b of the profile rings 104a and 104b (FIG. 4). From 0° to 10° both contours 103a, 103b are stable at a height of 10 mm. From 10° to 80° both profiles drop parallel, whereby in the projection of FIG. 5 the contour lines coincide. In this way the rotation of the plate or disk 104 leads to a down movement of the arms without opening of the arms (see also FIGS. 6a, 7a and 6b, 7b). After 80° the outer contour 103a drops more than that inner contour 103b, i.e. down to minus 2 mm. Thus, the arms 107a and 107b turn around the fulcrums 114a and 114b to open the grippers 119 and the arms, respectively, (FIG. 6c, 7c). From 100° to 170° both profiles moving parallel with a constant difference so that the arms go up, but stay open (FIG. 6d, 7d). From 170° to 180° the outer profile 103a comes to the same height as the inner one 103b. The arms close again (FIG. 6e, 7e). A further movement of the plate 104 in the same direction up to a 360° would repeat the transfer motion described above. However, if the motion of disk 104 is reversed instead of the described place cycle a pick cycle would be initiated starting with the end position of the place cycle and ending with the start or up position of the place cycle. This functionality is also demonstrate in FIGS. 7a to 7e the arms 107 (107a and 107b) first move down from a height of 10 mm to the zero level point, which marks the maximum down positioning of the arms 107. A further rotation of the disk leads to the opening of arms and to the placing of the wafer on the chuck. By rotating backwards, i.e. from the 360° position to the 180° position or from the 180° position to the 00 position a wafer can be picked from the chuck and can be brought to the upper or storage position. Thus the functionality allows a fast swapping of wafers at the chuck with a handling tool that can handle only one wafer: Thereby the robot with only one arm puts the new wafer in the FSS-1, which is closed, by moving the wafer into the correct center position with an increased height to overcome the outer rims of the wafer retainer structure 119a and 119b. Than the robot (not shown) places the wafer down onto the support structure. Now the robot picks the old wafer from a chuck. After the wafer is removed from the chuck the FSS-1 places the wafer onto the chuck 120 by moving the sequence from FIG. 6a to 6e or 7a to 7e. The FSS-1 is now ready to accept the next wafer and the fast swapping cycle can start from the beginning. In the following reference is made to FIG. 8, wherein a front side perspective view of a further embodiment of the inventive apparatus FSS-2 is shown. FSS-2 displayed in FIG. 8 comprises tong-like arms 207 (right arm 207a and left arm 207b) and a driving mechanism 201. Each of the arms 207 consist of a guiding member 208 (208a right arm and 208b left arm), an extension member 209 (209a right arm and 209b left arm), a leg 210 (210a right arm and 210b left arm), and a gripper 99 (99a right arm and 99b left arm). The driving mechanism 201 is made up of an elevation contrivance 202 and a manipulator drive 203. It is the purpose of the manipulator drive to appropriately control, govern or drive the arms 207a, 207b, such that grippers 99a, 99b, in a tong-like movement, can pickup, hold, and release a wafer from a chuck or robot, etc. The elevation contrivance 202 encompasses a rectangular base plate to which an actuator 205 centrally is attached. At the front end corners of the base plate 204, the base plate 204 comprises through holes for attaching the base plate. The actuator 205 is a linear actuator, which has a spindle 216 at one side. For to accommodate actuator 205 on the base plate 204, base plate 204 further comprises a centrally positioned through whole, through which the actuator spindle 216 extends. It is the function of the elevation contrivance 202 to elevate manipulator drive 203 in a direction perpendicular to a plan defined by the movement of the arms 207a and 207b. Therefore the elevation contrivance 202 is affixed to the top side of the housing 227 of the manipulator drive 203 via its spindle 216 and linear guides 210 (linear guide 210a to the right side and linear guide 210b to left side of the actuator). The linear guides 210a, 210b consist of a pin 212 (212a and 212b) (FIG. 9) and a guide 211 (211a and 211b) which guide the elevation movement. The pins 212 are symmetrically arranged with respect to the linear actuator 205 and extend through respective wholes, which are comprised by the base plate 204. Pins 212 are attached to base plate by guide clamps 206 (206a and 206b), and co-operate with the guides 211, which are affixed to the top surface of housing 227 by means of flanges. Thus actuator 205, with its spindle, can move the housing 227 of manipulator drive 203 up and down if the actuator is appropriately charged by current via cable 214. On the front side of housing 227, in central position on the front, a holder 213 is attached to the housing 227, which carries a scanning sensor 226 that detects or checks the presents of wafer 215, i.e. it detects whether the arms 207 bear a wafer or not. The sensor 226 is fastened to the free end of holder 213, whereby the holder extends from housing 227 such that at least wafers or disks with two different diameters, for instance of 200 mm and 300 mm, can be detected. Turning now to FIG. 9, wherein the back side of the swapping apparatus FSS-2 of FIG. 8 can be seen. Note that there, the back plate of housing 227 of the manipulator drive has been removed. Thus, FIG. 9 freely shows the functional elements of manipulator drive 203. Therein two sides can be differentiated. The mechanism on the right drives the right arm 207a and the mechanism on the left drives the left arm 207b. The technical features of both sides are the same. Therefore the following description of the technical parts will be restricted to just the right hand side. The driving mechanism on the right side comprises a motor or linear actuator 217a (217b) which is held by bracket 248a (248b), and which drives a lead screw 218a (218b) that co-operates with the female thread of bracket nut 219a (219b), whereby, depending on the sense of direction of lead screw 218a (218b) bracket nut 219a is either moved to left or to right. Lead screw nut 220a (220b) secures bracket nut 219a (219b). Bracket nut 219a (219b) itself is connected with linear slide 221a (221b) which is joint with guiding member 208a (208b) (see FIG. 8). Linear slide 221a (221b) is guided by linear guide 222a (222b) in parallel to lead screw 218a (218b). Two pairs of limit sensors 223a (223b) and 224a (224b) are arranged along the guiding way of linear slide 221a (221b). The sensors 223a (223b), 224a (224b) interact with flag sensor 225a (225b) which is lodged to linear slide 221a (221b). The first pair of sensors 223a (223b) is positioned along the guide way such that a 200 mm wafer can be either released/picked or held by the arms' grippers 99b. This means that, in case when the bracket nut 219a (219b) and guiding member 208a (208b), respectively, is moved to the left side (the same is valid if guiding member 208b of the left side is moved to the right) the inner sensor 223a′ (223b′) of the pair 223a (223b) indicates via sensor flag 225a (225b) that arm 207a (207b) or gripper 99a (99b) has the right position to hold wafer 215 (FIG. 8), whereas if the guiding member 208a (208b) or gripper 99a (99b) is moved to the right (left) the outer sensor 223a″ (223b″) of the pair 223a (223b) indicates via flag sensor 225a (225b) that the guiding member 208a (208b) or gripper 99a (99b) has moved far enough that there will be no interference with the wafer left on a chuck or to be picked from a chuck, and thus, in any case, no damage of the wafer 215 will occur. The second pair of sensors 224a (224b) has the same functionality for wafers or disks with a diameter of 300 mm. Thus, the inventive swapping apparatus advantageously includes the possibility to swap disk-like members or wafers of different diameters. Moreover, a further sensor or limit switch 249 at the inside of the top plate of the housing 227 is provided which indicates the distance between the manipulator drive 203 and the elevation contrivance 202. Another advantageous feature of the FSS-2 according to FIGS. 8 and 9 is the fact that the inventive swapping station can be front as well as back loaded. Structurally this is provided by the fact that the arms 207a and 207b are formed and hanged up on the manipulator drive 203 such that the grippers 99a, 99b are free accessible from the front and the back side of housing 227. For that function the part of guiding members 208a and 208b extending through the guiding apertures of the housing 227 is cranked, and the legs 210a, 210b are attached to the adjustable extension members 209a, 209b, which link the respective guiding members 208a, 208b and legs 210a, 210b, such that an offset of the grippers 99a, 99b and the legs 210a, 210b with respect to the outer side of base plate 251 of housing 227 is achieved. The offset preferably is 10 mm. Although not shown in FIG. 8 or FIG. 9, the displayed apparatus of course also comprise appropriate interfaces and cables connected thereto for a remote control of the apparatus' movements. A slightly different embodiment of the invention, if compared to that according to FIGS. 8 and 9, is shown in FIG. 10. Therein a schematic top view of the manipulator drive together with the tong-like arms of FIG. 8 is illustrated which differentiates in the fact that not two motors or linear actuators 217a, 217b are used but only one actuator 217 to drive the twin lead screws 218a, 218b and thus the arms 207 or grippers 99 on the right and on the left in FIG. 8 or 9. However for to get the tong-like movement of the arms 207a and 207b the lead screws preferably have different thread leads, i.e. the twin lead screws could be for instance to the right 218a left-hand threaded and that to the left 218b right-hand threaded or vice versa. Of course, the same effect could be achieve if the single actuator or motor 217 were able to provide two different driving directions for the two twin lead screws 218a and 218b with the same lead each. Thus, if driven by the motor 217, twin lead screws 218a and 218b cause an anti-parallel tong-like movement of the arms 207a, 207b. In the embodiment of FIG. 11 the single motor or actuator 217 with two driving shafts 229a and 229b (FIG. 10) for the twin lead screws 218a, 214b is replace by a motor 217 with merely one driving shaft 229 which drives a pulley 230 that by means of a belt drive 231 runs a driven pulley 232. The driven pulley is axially connected with the two twin lead screws 218a and 218b, as it is case with respect to motors according to FIG. 8 to 10. This kind of assembly just provides one sense of rotation of the driven pulley 232 and the twin lead screws 218a and 218b. Therefore, the lead screws 218a and 218b have to have opposed thread leads for a tong-like movement of the arms 207a and 207b. FIG. 12, as FIGS. 10 and 11, displays, under omission of the elevation contrivance 202 (FIGS. 8, 9), a schematic top view of a further embodiment of the manipulator drive 203 and the tong-like arms, whereby, as in FIGS. 10 and 11 the elevation contrivance, remains the same as in FIGS. 8 and 9. Manipulator drive 203 in FIG. 12 comprises a gear drive 233 and a lever apparatus 234 (234a and 234b) for driving the tong-like arms 235 (235a and 235b). The gear drive 233 consists of two gears 233a and 233b, which are in mesh. One of the gears 233b is driven by a pulley 238 via pulley 232, which has a rearward position inside the manipulator 203 on the symmetry axis of the swapping. This pulley 238 is driven via belt drive 236, which transfers the motion of a driving pulley 238 that is attached to and driven by an actuator or motor 237. The lever apparatus 234 of FIG. 12 encompasses two lever structures 234a and 234b. Part of the lever apparatus or structures 234a and 234b are the tong-like arms 235a and 235b. Each of the lever structures 234a and 234b forms a parallelogram of four levers 240, 241, 242 including the portions 239a and 239b of the arms 235a and 235b. In each of the lever structures 234, for gripping the wafer by means of the grippers 99a and 99b, the arms 235 and thus the portions 239 (239a and 239b) too are brought into a position parallel to a tangent on the edge of the disk or wafer 215. Each of the lever structures 234a and 234b comprises four cylindrical joints, which form the edges of the parallelogram. The joints 245 and 246 at the ends of the levers 242a and 242b parallel to the arms' portions 239a and 239b are locally fixed inside the manipulator drive 203, whereby the levers 242 extend parallel to the gear wheels 233, and whereby the joints 246a and 246b at the ends of levers 242a and 242b opposed to the wafer are locally affixed to the hubs 243a and 243b of gear wheels 233a and 233b. Moreover, with respect to the lever apparatus 234a (234b) lever 241a (241b on the left side), which is parallel to lever 240a (240b on the left side), is pinned to pinion or gear 233a (233b on the left side) by means of attachment point 244. On the basis of the above described structural elements of the embodiment according to FIG. 12 it is provided that if the actuator 237 drives or turns left gear wheel 233b to the left right gear wheel 233b will be turn to the right. Since lever 241a and 241b are fixed to the respective gear wheels 233a and 233b and are jointly fixed at the hubs 243a and 243b, these levers will be also turned to the respective direction, i.e. lever 241a will turn to the right around turning point 243a, and lever 241b will be turned to the left around turning point 243b, whereupon the levers 240a and 240b being parallel to levers 241a and 241b will follow the movement of levers 241a and 241b around the affixed joints 245a and 245b. By, for instance, turning the levers 241b and 240b to the left the distance of their free ends 247b and 248b will be increased with respect to the wafer 215, which results in a movement of the arm 235b to the left. Since levers 241b and 240b rotate the same angle to the left, there is a parallel offset of arm 235 to the left. The functional description for the left lever structure 235b is also valid for the right lever structure with the exception that the levers act in opposite direction. This is of course necessary for achieving the tong-like movement of arms upon which wafer 215 is supposed to be gripped or released. Now reference is made to FIG. 13. FIG. 13 shows the accelerated handling process or transfer of a wafer according to the invention from, for instance, a wafer container-cassette to, for example, an inspection station (both not shown). In that process, a wafer, which has just been inspected, is brought by a chuck of a x-y-stage to an exchange-region EXR. Therein, one of the inventive swapping apparatus FSS-1 or FSS-2 is located and awaits the coming of the wafer 315 (FIG. 13A). The arms 307a and 307b of the swapping apparatus FSS-2 are in their down and open position. Functionally, this could be for instance done be the elevation contrivance 202 and by the manipulator drive 203 according to one of the described embodiments. In FIG. 13B the x-y stage with chuck 320 moves the wafer 315 into the inventive swapping station FSS-2, i.e. between the arms of FSS-2. Swapping station FSS-2 grips and lifts, i.e. front loads the wafer from the chuck by means of the inventive driving mechanism 301 and the arms 307a and 307b. Having just picked the wafer from chuck 320 a new wafer 315′ to be inspected is brought to the exchange-region EXR by robot 350. The robot places new wafer 315′ onto chuck 320 beneath swapping station FSS-2 (FIG. 13C). Now the x-y-stage retracks chuck 320 from the exchange position EXR to the inspection station with new wafer 315′ (FIG. 13D). After or parallel to this robot 350 picks the old wafer 315 from the FSS-2 and retracks its arm with the old wafer 315 from the inventive swapping station FSS-2 (FIG. 13E). In the following, chuck 320 and robot 350 are both retracked, whereby robot 350 holds old wafer 315 and the chuck the new wafer 315′ (FIG. 13F). FIGS. 14A to 14F show the same process as FIGS. 13A to 13F with the difference that the swapping station FSS-2 or FSS-1 is first back-loaded with a new wafer 315′, and afterwards releases the new wafer 315′ to the chuck. Thus, the first picture FIG. 14A shows robot 350 coming to the exchange region EXR, where the FSS-2 waits to accept wafer 315′. Having arrived at the exchange position the robot, beneath the FSS-2, places the new wafer on the FSS-2, which is, with its arms, in the up and hold position (FIG. 14B). Parallel and/or after this the x-y-stage with its chuck comes to the exchange region EXR or exchange position, where the arms of the FSS are positioned. The robot handler 350 retracks from the swapping station FSS-2 (FIG. 14C). Arrived at the exchange position, the robot gets the old wafer 315 from the chuck of the x-y-stage (FIG. 14D). Now, Robot 350 retracks its arm with the old wafer 315 from the chuck 320, and the FSS places new wafer 315′ onto the chuck 320 of the x-y-stage (FIG. 14E). Then, x-y-stage retracks chuck 320 with new wafer 315′, and Robot 350 brings the old wafer 315 to, for instance, a container-cassette. Although the preferred embodiments of the invention has been described, it is to be understood that the invention is capable of other adaptations and modifications within the scope of the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The invention relates to an apparatus for swapping at least one disk-like member, a method for transporting wafers, and a handling line for carrying out the method for transporting wafers. 2. Description of Related Art Apparatus for accepting and transferring wafers are well known in the art. For instance, robot handlers are commonly used to move materials, e.g. semiconductor wafers, between different stages of a wafer fabrication process. In this regard, robot handlers might be used to move the wafer from a plasma etch station in a cluster tool to a deposition station or from a manufacturing station to a testing station or metrology tool, wherein the wafer is positioned onto a chuck. In this kind of handling system the throughput depends strongly on the time the metrology tool has to wait for material handed over by the robot handler. A typical transporting or handling scenario for a wafer handling system is the following: a) the handling system, typically a one-arm-robot-handler gets a new wafer, b) the handling system moves and loads the wafer onto the transfer position for transferring the wafer for example into the metrology tool, c) the wafer gets moved into the tool for processing or measuring; after this the wafer gets back to the transfer position or unload position which is typically the same as the load position, d) the handling system, i.e. the robot handler, picks the wafer and unloads the wafer to the next position, The cycle starts from step a) During the processing of the wafer in the metrology tool the handling system or robot waits or is doing different tasks. But for doing different tasks the handling system has to do motions without wafer. This however is ineffective and forms a bottleneck of the transport system, which limits the throughput. The problem might be solved by employing a so-called dual-arm or paddle-robot that can handle two wafers at the same time. However, such a handling system has a increased footprint, since the arms increase the sweep radius of the robot, which is caused by the space that is needed horizontally to swap the wafer at the desired station. Yet, space in a clean room environment, which is commonly needed for wafer production, is a scarce resource. Therefore, an increase in food print of the handling system would raise production costs considerably. Moreover these kind of robots are more complex in handling and their purchase price is high. Therefore, a solution is needed which on the one side increases the throughput and on the other minimizes the space consumption and the additional footprint, respectively, needed. These and other disadvantages have lead to the object of the present invention to provide an apparatus as a part of a handling system which avoids to use complex handling systems with a big footprint but nevertheless can increases the throughput considerably. | <SOH> SUMMARY OF THE INVENTION <EOH>The inventive solution is obtained by the provision of an apparatus for swapping at least one disk-like member, e.g. a wafer. The apparatus includes at least two tong-like arms for accepting and holding the disk-like member and a driving-mechanism adapted to drive the arms. The mechanism is adapted to provide a first and a second movement of the arms, whereby the first movement is a vertically oriented movement of the arms and the second movement is a horizontally oriented tong-like movement of the arms. Thus far, in general, the invention is an apparatus for swapping at least one disk-like member, e.g. a wafer, the apparatus comprises at least two tong-like arms for accepting and holding the disk-like member and a driving-mechanism adapted to drive the arms, wherein the mechanism is adapted to provide a first and a second movement of the arms, whereby the first movement comprises a vertically oriented movement of the arms from an up to a down position and vice versa, and whereby the second movement comprises a horizontally oriented tong-like movement of the arms. The inventive apparatus, for example, can be advantageously simply arranged in-line or in series to an one arm handling system and a load position of, for instance, a chuck of a motion system which transfers a disk-like member or a wafer, e.g. into a testing station. In this regard the inventive apparatus is able to accept, hold or store the disk-like member with its tong-like arms, being driven by the driving mechanism, from the handling system, whereby, after having placed the disk-like member or wafer into the arms of the inventive apparatus, the unloaded handling system can pick another wafer from, for instance the chuck, coming out of the testing station. If these steps are completed, the inventive apparatus is highly advantageous able to transfer or place or swap the stored wafer with its tong-like arms on the load position or chuck to be transferred into the testing station. Of course, the just described cycle works also the other way round. Thus, any motion of the handling system without wafer can be avoided if the inventive apparatus is applied. It should be emphasis that according to the invention the term disk-like member, in its meaning, comprises any kind of member which can be swapped or transferred by means of the inventive apparatus, or which is adapted to be used within the inventive process. Thus, in the inventive sense disk-like members can be, for instance, round like a wafer, or rectangular like a plate, or can be of any appropriate shape. With regard to an advantageous further development of the inventive apparatus a lever apparatus and/or spindle means is provided which controls or governs the movement of the tong-like arms. Thus, the lever apparatus and/or spindle means together with the inventive driving mechanism, at least guarantees a movement of the tong-like arms into one hold and into one release position and vice versa. The hold position is characterized by the fact that in this position the arms are ready to accept and/or to hold a disk-like member or wafer, whereas in the release position the arms are opened such that a disk-like member can be charged or discharge by the arms. Thereby, it is guaranteed that especially in the case when the arms charge or grip a disk-like member or wafer the distance between the arms and the arms and the dislike member, respectively, is such that there will be no damage of the disk-like member. According to an additional advantageous further development of the inventive apparatus the driving mechanism is separated into an elevation contrivance and a manipulator drive. The manipulator drive causes the arms to perform a tong-like move in a plan, whereas the elevation contrivance preferably moves the arms and/or the manipulator up and down, i.e. in a direction preferably perpendicular to the plan defined by the tong-like movement of the arms. Advantageously, both movements, and thus both apparatus can be controlled independently. Yet, with regard to another preferred embodiment of the invention, it is provided that the driving mechanism or the manipulator drive comprises the functionality to move the arms into two different hold positions and into two release positions corresponding to the hold positions. This kind of functionality gives the possibility to use the inventive apparatus for different kind of disk-like members, e.g. for wafer with different diameters. So far, the inventive apparatus might be for example used for wafer seizes with a diameter of 200 mm or of 300 mm. In connection with this, the invention also provides extension members that are part of the arms, and which advantageously allow to flexible adjust the feed opening or the distance between the arms. This opens up the possibility to use the inventive apparatus for swapping disks with not only two or three different diameters but with all kind of diameters. Another structural element of the invention which positively further develops the inventive apparatus is given if the apparatus comprises gripping means which helps the arms to grip the disk-like member. The gripping means contacts the edges of the disk-like member, when it is held or gripped by the inventive apparatus or tong-like arms. For that purpose, advantageously the gripping means comprises at least one grooved circular ring section, which is adapted to the radius or diameter of the wafer to be gripped. For to provide a compact assembly the inventive apparatus comprises a housing, wherein at least a part of the driving mechanism for the tong-like arms is accommodated. Thereby openings are provided through which the arms extend for to grip the disk-like member. Advantageously, moreover, it is given that the arms are formed in a way that enables the apparatus and the arms respectively to be front- or to be back-loaded. Front-side in this respect is the side to which the arms extend to, and back side is the side in opposition to the front-side. According to another further development of invention the inventive apparatus or driving mechanism comprises at least one driving motor, which one the one side drives the vertical movement of the tong-like arms via the lever apparatus and/or spindle and which on the other side also drives the horizontal movement of the arms. Highly advantageously, according to the invention, the inventive apparatus also comprises sensor means for detecting the disk-like member, i.e. for to tell the apparatus whether there is a disk-like member or not inside the inventive apparatus and/or for detecting the position of the tong-like arms. For the latter purpose sensors, for instance, can be arranged in pairs with respect to the arms such that they are able to indicate at least two different relative positions of the arms to each other. In this respect, one of the sensor, for example, could indicate the hold position of the respective arm and the other the release position of the respective arm. The same applies if the inventive apparatus is dimensioned for disk-like members of different diameter, whereby for each disk-like member a hold and a release position can be defined via the arrangement of sensors or via sensor readings. Moreover, sensors could be provided which indicate the height of the arms with respect to a defined level. According another aspect of the invention the inventive apparatus favorably comprises or is connectable to control means for controlling the movement of the arms and/or motor drives etc. For that purpose appropriated interfaces and at least one micro-controller are/is provided. Additionally to the above stated, it is a further object of the present invention to provide a method which by use of the inventive apparatus avoids to use complex handling systems but nevertheless increases the throughput considerably. Therein a method for handling or transporting disk-like members, e.g. wafers, is defined, wherein an apparatus as described above is positioned into an exchange-region for exchanging dislike-members, for that purpose a first disk-like member with first transport means from a first position is transported to the exchange region, at the exchange region the first disk-like member is loaded into the inventive apparatus, after or parallel to the latter load or even before the latter load a second disk-like member with second transport means is transported to the exchange region, the second disk-like member, after having unloaded the first transport means, the second disk-like member is loaded from the second transport means to the first transport means, and after having unloaded the second transport means, the first disk-like member gripped, loaded or charged by the inventive apparatus is transferred from the inventive apparatus to the second transport means, if this is done the second disk-like member can be transported to a second position by means of the second transport means. The cycle can start again. An even further object of the invention is to provide a handling line to accomplish the just described method. The inventive handling line comprises respective means for carrying out the method. Thus, in particular, it might comprises a x-y-stage or a chuck and/or a robot to replace either the first or the second transport means. | 20040326 | 20070626 | 20050616 | 63074.0 | 0 | UNDERWOOD, DONALD W | FAST SWAPPING STATION FOR WAFER TRANSPORT | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,810,485 | ACCEPTED | Spreader | A spreader is disclosed for allowing a user to spread a spreadable food item. | 1. For use with a hand manipulable flowable, spreadable material dispenser, the combination comprising: a. a dispensing nozzle associated with the dispenser to dispense said material; b. and a spreader surface associated with the nozzle whereby the dispenser may be manipulated to cause the spreader surface to spread material dispensed via the nozzle. 2. The combination of claim 1 wherein the spreader surface has the form of a blade or spatula surface attached to the dispenser. 3. The combination of claim 2 wherein the spreader surface is proximate the nozzle. 4. The combination of claim 1 wherein the spreader has the form of a flap or blade, located at a nozzle outlet from which the material is dispensed, the flap or blade being flexible. 5. The combination of claim 1 including said dispenser carrying the nozzle, and inserting dispensable edible material in the dispenser to be spread by the spreader. 6. (canceled) 7. The combination of claim 1 wherein the nozzle has a fitting to attach to the dispenser. 8. The combination of claim 7 wherein the fitting comprises threads. 9. (canceled) 10. The combination of claim 1 wherein the nozzle comprises a wide, narrow flange with a slit from which to permit the flow of flowable material. 11. (canceled) 12. (canceled) 13. (canceled) 14. The combination of claim 1 wherein the nozzle has an undulated shape to produce a flowable material with a wavy texture. 15. (canceled) 16. (canceled) 17. (canceled) 18. (canceled) 19. (canceled) 20. (canceled) 21. (canceled) 22. (canceled) 23. The combination of claim 1 wherein the spreader is angled so as not to engage the layered spread material as the material is dispensed through the nozzle. 24. (canceled) 25. (canceled) 26. The combination of claim 1 including a cap fitting endwise over the nozzle and over the spreader surface. 27. The combination of claim 26 wherein the cap has an interior configuration to conform to the nozzle and a nozzle outlet and to the spreader surface. 28. (canceled) 29. A spreader, comprising: a container, having a closed end and an open end, capable of holding a spreadable food item; and a nozzle, mounted at the open end of the container, and having an opening in fluid communication with the open end of the container such that the spreadable food item can flow through the opening of the nozzle. 30. (canceled) 31. (canceled) 32. The spreader, comprising: a container, having a base and a lid opposite the base, the container capable of holding a spreadable food item; a detachable handle mounted on the container; a plunger, adapted to engage the detachable handle such that when the detachable handle is depressed, the plunger exerts pressure on the spreadable food item in the container; and a dispenser nozzle, mounted on the exterior of the container proximate to the base of the container, in fluid communication with the interior of the container such that the spreadable food item may be forced through the dispenser nozzle. 33. The spreader of claim 31, wherein the detachable handle is mounted on the container along the exterior of the container generally flush with the exterior of the container. 34. The spreader of claim 32, wherein the detachable handle is mounted on the container at the lid in engagement with the plunger. 35. The spreader of claim 32, wherein the dispenser nozzle is in a first upright position, such as for storage. 36. The spreader of claim 32, wherein, the dispenser nozzle is in a second position, generally perpendicular to the container for dispensing the food item. 37. A spreader, comprising: a container; a bag, disposed within the container for holding a food item; and a nozzle, mounted at an open end of the container. 38. The spreader of claim 37, further comprising a threaded end disposed at the open end of the container. 39. The spreader of claim 37, wherein the nozzle further comprises a thread for engaging the threaded end of the container. 40-63. (canceled) | CLAIM OF PRIORITY This application is a continuation in part of U.S. Ser. No. 10/628,097 filed Jul. 28, 2002 and U.S. Ser. No. 10/761,132, filed Jan. 20, 2004. FIELD OF THE INVENTION The present invention relates to flowable material spreaders for use on hand manipulatable dispensers, and more particularly to spreaders at the nozzle ends of such dispensers. BACKGROUND OF THE INVENTION Spreadable foods are common table items and are enjoyed by many all over the world. There are numerous types of foods that can be spread. Typical spreadable foods include peanut butter, frosting, butter, mayonnaise, jelly, ice cream toppings, salad dressing and cream cheese and other edible spreads for use on bread, crackers, and the like. Often, a butter knife, spatula, or other similar device is used to spread the food onto the bread, cracker, or other item. However, these utensils can become lost on or at outdoor celebrations and picnics, or other events, or need to repeatedly dip a spreader knife into a jar. Additionally, material accumulates on the knife and jar edges, as well as crumbs of other materials can accumulate in the jar. A number of patents have issued related to food dispensers and the like. U.S. Pat. No. 5,377,874 discloses a liquid dispenser for dispensing fluid condiment materials, such as ketchup, mustard and mayonnaise as well as other liquids such as medicated salves, lotions and ointments. The dispenser includes a tubular body with a spherical plunger element connected to a spreader paddle member disposed within a tubular body. Upon external manipulation of the tubular body, the spherical plunger and spreader paddle arrangement is urged toward a dispenser nozzle for release of condiment filling contained therein. The sanitary spreader paddle simultaneously protrudes from within the tubular body as condiment filling is being evacuated. As a result, the user may evacuate the entire volume of condiment filling within the dispenser as well as spread the deposited condiment filling on a food article to be eaten. In a medical application of the invention, the dispenser includes an integral applicator swab which is connected to the spreader paddle and resides within the plunger. The spreader paddle is separated from the plunger to expose the cleansing swab for use on the body. U.S. Pat. No. 5,330,075 is directed to a food condiment dispenser for dispensing fluid condiment materials, such as ketchup, mustard and mayonnaise. The dispenser includes a tubular body with a spherical plunger element connected to a spreader paddle member disposed within a tubular body. Upon external manipulation of the tubular body, the spherical plunger and spreader paddle arrangement is urged toward a dispenser nozzle for release of condiment filling contained therein. The sanitary spreader paddle simultaneously protrudes from within the tubular body as condiment filling is being evacuated. As a result, the user may evacuate the entire volume of condiment filling within the dispenser as well as spread the deposited condiment filling on a food article to be eaten. U.S. Pat. No. 4,957,226 is directed to an automatic food dispensing method, apparatus and utensil primarily for use in fast food restaurants, bakeries, and the like. The method and apparatus comprise a pumping system from a supply through a pump in a controlled amount with a reverse action of the pump after the appropriate amount has been dispensed in order to avoid it dripping. Other drip proof arrangements, such as valving are also utilized optionally. The utensil comprises a handle attached to a container and spreading utensil such as a spoon, ladle, or the like, wherein predetermined portions of a food or substance used in a food may be dispensed either continually or as predetermined quantities. The device consists of a spoon or other appropriately shaped utensil attached to a hollow handle which terminates in a non-interfering connection with the interior of the utensil at one end and terminates at the other end in a connection to a food supply source. U.S. Pat. No. 6,153,238 is directed to a packaged cheese product comprising a hermetically sealed container, preferably a pouch, made out of flexible material; a decorator tip or adaptor therefore inside the container, a cheese product inside the container and a cap for closing the decorator tip when the pouch is partially emptied. The cheese product can be extruded after cuffing the corner off of the pouch and seating the decorator tip in the resulting opening. Cheese in decorative shapes can then be easily applied as a garnish on food items and the pouch can then be re-closed by capping the decorator tip. The cap preferably has a bulb member that fits inside the decorator tip and a skirt member that fits around the outside petals of the preferred decorator tip. U.S. Pat. No. 4,844,917 is directed to a cake frosting technique and assembly including a disposable frosting bag for home or commercial use to render the frosting or decorating of cakes or other pastries more convenient and expeditious by the complete elimination of the need for expensive and messy heretofore-used large commercial squeeze bags, or manually whipped and spread frosting, or expensive aerosols. The invention contemplates the ready coloring or tinting of the frosting to any desired hue within a wide range with any particular color and further contemplates the imparting of any desired flavoring to the frosting by the separate and conveniently associated provision of the aforesaid disposable bag containing a neutral or white frosting along with a plurality of separate color tint tubes and a plurality of separate flavor taste tubes, whose contents are to be admixed respectively with the base frosting material to achieve a desired blend for the ultimate decorative and taste effects contemplated. U.S. Patent Publication No. 2002/0000441 discloses an aperture forming structure, which when attached to or integrally formed in dispenser packages for flowable substances allows reclosure and single or multiple uses. The aperture forming structure includes a breakaway tip member of thermoformable plastic. The break away tip includes a hollow protrusion from a surface. The intersection of the hollow protrusion and the surface is a fault line. Rupturing of the fault line creates an aperture from which the contents of the dispenser package may exit. A cap may be integrally formed with the aperture forming structure and detached for protecting the hollow protrusion or for closing the aperture created when the fault line is ruptured. The aperture forming structure can be made by heating a relatively stiff substantially flat thermoformable sheet of and then stretching the sheet to create a first and a second hollow protrusion in a tiered configuration. A rupture line is placed at the intersection of the first and the second protrusions. The sheet may be attached to a pouch or containment member formed from a flexible sheet which contains any flowable substance. While there have been a number of prior systems directed to food spreaders, none have adequately addressed the need for ease of use and convenience. There is a need for a system to easily, quickly and accurately spread material such as edible substances, being dispensed from containers such as squeeze tubes or bottles. OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to provide a spreader that will allow a user to spread a spreadable food item. It is a further object of the present invention to provide a spreader having a dispensing nozzle associated with the dispenser to dispense said material, and a spreader surface associated with the nozzle whereby the dispenser may be manipulated to cause the spreader surface to spread material dispensed via the nozzle. It is a further object of the present invention to provide a system in which the spreader is flexible and can be viewed in use. It is a further object to provide a spreader in which the spreader is dome-shaped. It is a further object of the present invention to provide a spreader which has a number of orifices, having different shapes and configurations, including dome shapes. It is yet another object of the present invention to provide a spreader which includes expandable nipples. It is yet a further object of the present invention to provide a spreader, including a container, having a base and a lid opposite the base, the container capable of holding a spreadable food item; a detachable handle mounted on the container; a plunger, adapted to engage the detachable handle such that when the detachable handle is depressed, the plunger exerts pressure on the spreadable food item in the container; and a dispenser nozzle, mounted on the exterior of the container proximate to the base of the container, in fluid communication with the interior of the container such that the spreadable food item may be forced through the dispenser nozzle, the dispenser nozzle capable of being in a first position or a second position. In accordance with a first aspect of the present invention, a novel spreader is disclosed. The novel spreader includes a dispensing nozzle associated with the dispenser to dispense said material, and a spreader surface associated with the nozzle whereby the dispenser may be manipulated to cause the spreader surface to spread material dispensed via the nozzle. In accordance with another aspect of the present invention, a novel spreader is disclosed. The novel spreader includes a container, having a closed end and an open end, capable of holding a spreadable food item, and a nozzle, mounted at the open end of the container, and having an opening in fluid communication with the open end of the container such that the spreadable food item can flow through the opening of the nozzle. In accordance with yet another aspect of the present invention, a novel spreader/dispenser is disclosed. The novel spreader/dispenser includes a container, having a base and a lid opposite the base, the container capable of holding a spreadable food item; a detachable handle mounted on the container; a plunger, adapted to engage the detachable handle such that when the detachable handle is depressed, the plunger exerts pressure on the spreadable food item in the container; and a dispenser nozzle, mounted on the exterior of the container proximate to the base of the container, in fluid communication with the interior of the container such that the spreadable food item may be forced through the dispenser nozzle, the dispenser nozzle capable of being in a first position or a second position. The nozzles of the present invention can be used to spread a large variety of items in a variety of formats. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing summary, as well as the following detailed description of a preferred embodiment of the present invention will be better understood when read with reference to the appended drawings, wherein: FIG. 1 is a side elevation of a spreader in accordance with the present invention; FIG. 2 is a perspective top plan view of the FIG. 1 spreader; FIG. 3 is a front elevation of a spreader dispensing opening; FIG. 4 is a view like FIG. 2 but showing a spreader flexible dispensing nozzle; FIG. 4a is a spreader flexible dispensing nozzle having a wavy texture; FIG. 5 is a side elevation of a spreader nozzle; FIG. 6 is a top plan view of a spreader cap; FIG. 7 is a view of an entrance at the inlet end of a spreader as in FIG. 5; FIG. 8 is like FIG. 7, showing a different entrance configuration; FIG. 9 is a side elevation showing the end of a container to which a spreader cap attaches; FIG. 10 is a frontal view of the FIG. 9 container end; FIG. 11 is a side elevation showing a spreader or narrowed configuration; FIG. 12 is a side elevation of the discharge end of a container to which the FIG. 11 spreader attaches; FIG. 13 is a top plan view of a spreader discharge end, with a serrated edge; FIG. 14 is a view like FIG. 13 showing a nozzle discharge end with serrated edge; FIG. 15 is a side elevation showing a nozzle with a retracted movable spreader, and control; FIG. 16 is a view like FIG. 15, showing the movable spreader in extended position; FIG. 17 is like FIG. 15 but showing the movable retractable spreader at the underside of the nozzle; FIG. 18 is a top plan view of a nozzle with an associated retractable and extendable spreader; FIG. 19 shows a modified nozzle and spreader; FIG. 19a shows the FIG. 19 spreader in tilted position, for spreading use; FIG. 20 shows a curved flap or blade; FIG. 21a is a side elevation of an alternate embodiment of a spreader outfitted with a knife nozzle in accordance with the present invention; FIG. 21b is a side elevation of an alternate embodiment of a spreader outfitted with a spatula nozzle in accordance with the present invention; FIG. 22a is a front elevation view of an alternate embodiment of a spreader/dispenser in accordance with the present invention; FIG. 22b is a partial front elevation view of the spreader/dispenser of FIG. 22a in an alternate configuration; FIG. 23 is an exploded view of an alternate embodiment of a spreader and nozzle in accordance with the present invention; FIG. 24 is a front elevation view of an alternative embodiment of a spreader with nozzle and handle in accordance with the present invention; and FIG. 25 is a front elevation view of the spreader of FIG. 24 shown with a cap for the nozzle. FIG. 26 is a further alternative embodiment of a nozzle. FIG. 27 is still yet a further embodiment of the nozzle of the present invention. FIGS. 28a-28b are another embodiment of the nozzle spreader of the present invention. FIGS. 29 and 29b is another embodiment of the nozzle spreader of the present invention. FIG. 30 is another embodiment of the nozzle spreader of the present invention. FIGS. 31 and 31a are another embodiment of the nozzle spreader of the present invention. FIGS. 32a-32c is yet another embodiment of the present invention which includes a dome-shaped configuration. FIGS. 33a and 33b illustrate the slit openings of the present invention. FIGS. 34a-34b illustrate yet another alternative embodiment in which the dome-shape application is inserted into the throat of the bottle. FIGS. 35a-35e are perspective views of caps which are over the dome of the present invention. FIGS. 36a and 36b illustrate another embodiment of a flange-shaped dome closure system for use in the present invention. FIGS. 37a through 37f illustrate a dial-type dome applicator/spreader in accordance with the present invention. FIG. 38 illustrates a dome having a plurality of orifices having different sizes. FIG. 39 illustrates an embodiment in which the dome is pyramid sloped. FIG. 40 illustrates an alternative nozzle embodiment of the present invention having a dome-shaped applicator. FIG. 41 illustrates alternative orifice embodiments. FIG. 42 illustrates a nipple-based embodiment for use in the preferred embodiment. FIG. 43 are views of nipple embodiments of the present invention. FIG. 44 is an embodiment of the invention in which the orifices are angled. FIGS. 45a and 45b illustrate another dial-type embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference numerals refer to the same components across the several views and in particular to FIGS. 1 and 2, there is shown a spreader 10. The spreader 10 contains dispensable, flowable food material such as peanut butter, jelly or other such edibles. When the container is squeezed, the material flows through a nozzle 11 which tapers toward an outlet 12 which is elongated laterally, to provide a dispensed layer 13 of material of thickness 14 substantially less than its width 15. A flexible spreader 17 in the form of a flap or blade, or spatula, is provided at the nozzle exit, to face the layer 13 exiting from the nozzle, whereby the user can manipulate the spreader, and its undersurface, via container manipulation, to further spread or shape the dispensed layer 13. The flap or blade may be stiff or sufficiently flexible to shape the layer 13. Note its lateral length 19 is substantially greater than its width. The tip of the nozzle or blade should be flexible The nozzle 11 may be stiff or may be flexible as in FIG. 4 to assist flexing of the spreader during container manipulation to cause the spreader to shape the layer 13 deposited on a surface 21 or spread it only after it is dispensed. The latter may be a food surface such as on bread, or other substances. FIG. 3 shows the nozzle outlet 22, which has lateral width 22a substantially greater than its thickness 22b. The nozzle may be a cap on the container, or may be integral with the container. A snap-on or threaded fitting 24 connects the nozzle to the container, in FIG. 4. As shown in FIG. 4a, the extruded product can have a wavy texture. FIGS. 5 and 6 show a nozzle 32, tapering toward a narrowed exit 33 with a spreader flap or blade 34 overhanging that exit. The blade 34 is preferably flexible. FIG. 6 shows a cap 190 that receives the nozzle with snap-ring retention at 188 in a cap recess 188a of nozzle end 32a. Cap inner wall 189 forms a recess to receive the nozzle. A plug 192 on the cap plugs outlet 33. FIG. 7 shows the exit 33 as laterally, elongated with narrowed width or height. The nozzle entrance is seen at 34, in FIG. 8. FIG. 9 shows dispenser threads 36 to which the nozzle may threadably or otherwise attach. FIG. 10 shows in frontal view the annular end of the thread 36. See end opening 10a. FIG. 11 shows a flexible nozzle 40 that tapers toward an outlet 41, such as an elongated slit. The nozzle tip 40a serves as a spreader and preferably is positioned so that it can be seen when in use. The nozzle has a fitting 43 that threadably attaches to dispenser threads 44, as seen in FIG. 12. Nozzle may alternatively be positioned via a snap and release mechanism. FIG. 13 shows a spreader flap 46 that has a laterally elongated serrated edge 47 to engage the dispensed layer 48 being dispensed. As a result, the layer 48 has an attractive striated appearance. The nozzle can be waved laterally back and forth to produce wavy elongated striations on the dispensed layer surface. FIG. 14 shows similar serrations 50 on the end of a nozzle 40b. A flap 51 can be attached to the nozzle to overlie the serrations, or part of same. In FIG. 15, the flap or blade 60 is carried for adjustable movement, as by a carrier or adjuster 61 on the nozzle. A finger engagable protrusion 61a on the carrier is manipulated to move or slide the blade and carrier toward or away from the nozzle exit 41a, thereby to adjust the exposure of the blade to the dispensed material, to provide additional flexibility of use of the blade. Grooving 63 in the nozzle in the form of a threaded cap 63a, guides the adjuster. FIG. 16 shows the blade in extended forward position. The dispensing nozzle cavity appears at 64. FIG. 18 is a top plan view of the FIG. 16 adjuster. stature 17 shows the adjuster at the bottom side of the nozzle 93, having an exit 93a and pusher. The option of depositing the layer 113 without interference with the spreader flap or blade, is preserved. In FIG. 19 a spreader 110 blade or flap 110a carried at 111 by, and may be fixedly or releasably attached to or integral with, a nozzle 112. See bond zone at 111. The spreader and nozzle are shown being moved to the right. See arrow 125, and a layer of dispensable material 113 is deposited on substrate 126, via bore 112a of the nozzle. Material 113 is typically edible, and may consist, for example, of peanut butter, butter, frosting, mayonnaise, jam, jelly, soft cheese, or other edibles. In FIG. 19, the spreader 110 as supported is angled, relative to the nozzle or its bore, so that the spreader flap terminal 11a is sufficiently offset from the nozzle outlet 112a by a sufficient distance, that the terminal tip 110a does not engage the top 113a of the deposited layer 113, as during depositing of the layer. Terminal 110a may consist of an elastomer such as rubber. Outlet 112a may be laterally elongated as in FIG. 7. In FIG. 19a the nozzle is now further tilted, as at angle a, so that the spreader blade terminal tip 110a engages the surface of the layer 113, for spreading purposes. Terminal 110a is shown as arcuately flexed near the tip, to smoothly engage and spreadably deform surface 113a, as the nozzle is moved to the right, relative to 113. Note that the spreader body at 110c upwardly of terminal 110a is thickened so as not to flex, and so as to positively position the terminal 110a as it accurately wipes along surface 113a. Terminal 110a may or may not be flexible, but is preferably arcuately flexible to smooth and spread surface 113a, as the nozzle and supply container are manipulated. Body 110c tapers toward the tip or terminal. This construction, as shown, lends itself to ease of cleaning of interior surfaces 128,129, and 130, as well as cleaning of the terminal. Note the greater than 90 degrees angularities of adjacent surfaces 128 and 129, and 129 and 130, avoiding small gaps. The spreader terminal at 110a may have elongated lateral length, of dimension substantially greater than the nozzle discharge opening dimension, as described above in other FIGURES, for engaging the widened surface area of 113, achieved during spreading. FIG. 20 shows a curved flap or blade to conform to curvature of an edible, such as a corn cob. See laterally elongated nozzle outlet 22 having narrowed width 22b. A downwardly concave spreader flap or blade 17a is shown as above the outlet 22, and of lateral elongation greater than outlet 22 lateral elongation, indicated at 22a. FIG. 21a shows an alternate embodiment of the present invention that combines a knife and a spreader 200. The spreader 200 includes a container 201, that can hold a spreadable food F, such as peanut butter, butter, cheese, and the like. In a preferred embodiment of the present invention, the container 201 is flexible so as to allow a user to squeeze the spreadable food F. A knife nozzle 210 is attached to an open end of the container 201, and has an opening 220 to allow the spreadable food F to be transferred from the container 201 to an item such as bread, crackers, and the like. The knife nozzle 210 can then be used to spread the spreadable food F as desired. FIG. 21b illustrates another embodiment of the present invention that combines a spatula and a spreader 200′. The spreader 200′ includes a container 201′, very similar to the container 201 above, that can hold a spreadable food F, such as peanut butter, butter, cheese, and the like. In a preferred embodiment of the present invention, the container 201′ is flexible so as to allow a user to squeeze the spreadable food F. A spatula nozzle 210′, which may be flexible, is attached to an open end of the container 201′, and has an opening 220′ to allow the spreadable food F to be transferred from the container 201′ to an item such as bread, crackers, and the like. The knife nozzle 210′ can then be used to spread the spreadable food F as desired. Referring now to FIGS. 22a and 22b, another embodiment of a spreader 300 is illustrated. The spreader 300 includes a container 301, having a base 302 and a lid 303, that can hold a spreadable food F, such as peanut butter, butter, cheese, and the like. A detachable handle 310 is mounted on the container 301 at an attachment point 312 for transport and storage, to allow the spreader 300 to have less of a profile and take up less room. A dispenser nozzle 320 is mounted on the exterior of the container 301 to allow for the spreadable food in the container to be pushed out and onto a receiving food, such as bread, crackers and the like. When the spreader 300 is to be used, the detachable handle 310 is detached from the attachment point 312 and is mounted at mounting point 311, where it comes into engagement with a plunger 315, located in the lid 303. Additionally, the dispenser nozzle 320 may be rotated up or down, or flipped up in order to facilitate dispensing or storage as the case may be. When the handle 310 is depressed in the direction of arrow ‘P’, then the handle 310 exerts downward pressure on the spreadable food in the container 301, and forces the spreadable food out of the dispenser nozzle 320, and onto the receiving food. The interior of the dispenser is beveled 313 to facilitate the removal of all material. While this embodiment has be described in the context of longitudinally thrust plunger, it is to be appreciated that other equivalent structures could fulfill this function. For example the plunger could be thrust downward by means of a screw activated compression mechanism. Illustrated in FIG. 23 is another embodiment of a spreader 400. The spreader 400 includes a container 401 and a nozzle 420. The container includes a threaded end 426 and is capable of receiving a bag 410, which in turn holds a spreadable food such as peanut butter, butter, cheese, frosting, and the like. The bag 410 may be omitted altogether. The bag 410 is flexible in a preferred embodiment of the present invention and can be folded over the threaded end 415 of the container 401. The nozzle 420 includes an opening 425 and a threaded end 426 which threadedly engages the threaded end 426 of the container 401 to secure the nozzle 420 to the container 401. Additionally, the bag 410 is then secured into place as the overlap portion is secured between the threaded end 426 of the nozzle 420 and the threaded end 426 of the container 401. Referring now to FIGS. 24 and 25, another embodiment of a spreader 500 is shown. The spreader 500 includes a container 501, and a wide nozzle 520. Disposed within the container 501 is a bag 540 that can hold a spreadable food F, such as peanut butter, butter, cheese, frosting, and the like. The wide nozzle 520 is mounted at an open end 526 of the container 501, and includes an opening 525. Mounted on the container 501, at the opposite end 527 is a handle 510. The handle 510 includes a plunger 515, such that when the handle 510 is depressed in the direction of arrow ‘Q’, the plunger 515 forces the spreadable food contained within the bag 540 out through the opening 525 of the wide nozzle 520 and onto a receiving food, such as bread, crackers, cake, and the like. Additionally, a cap 530, having a cavity 531 substantially in the shape of the wide nozzle 520, can be mounted on the container 501 at the wide nozzle 520 in order to allow the spreader 500 to be stored standing upright. FIG. 26 illustrates yet another embodiment of a nozzle in accordance with the present invention. In this embodiment, a rubber or flexible nozzle 600 is affixed to a threaded member 610 and extended coaxially thereto. The rubber/plastic nozzle 600 can function as a spreader. FIG. 27 is still a further embodiment of nozzles in accordance with the present invention. FIG. 27 illustrates a nozzle 700 which either may be stiff or comprise a member expandable in accordion style when pressure is applied. FIGS. 28a and 28b are still yet a further embodiment of a spreader in accordance with the present invention. In this embodiment, the spreader is a cylindrical casing 800 with an adjustable spine 802, connected to an adjustment mechanism 804 and nozzle 807 permit the flow of condiments such as spread dressing. It is to appreciated that the adjustment mechanism 804 may comprise a drive crew or other similar device to longitudinally move the nozzle 807. The nozzle 807 may have holes to permit the flow of material there through. When the adjustment mechanism, is 804 pulled upward the nozzle 807 pulls upward and permits the flow of material. When pressure is applied the nozzle extends stiffly outward. This embodiment is similar in its operation to a garden nozzle. In a modified embodiment shown in FIG. 28b, the mechanism can have two positions, “on” and “off” 806, 808. FIGS. 29 and 29a illustrate yet another nozzle spreader embodiment. In this embodiment, the nozzle spreader comprises a flat, wide nozzle 900 having a plurality of shaped holes 902. The nozzle can have a flip cap 904, for example, and may have a cap or closure which has protrusions 906 to cover the holes. This embodiment is ideal for salad dressings or the like. As shown in FIG. 29a, the bottle can have a threaded attachment 908 and adjuster 910 to adjust the flow of material. FIG. 30 is a related embodiment to that of FIG. 29. In this embodiment, the nozzle comprises a flat, wide nozzle 1000 that inserts on a wide flange top 1002. The nozzle has a plurality of holes 1004 which may be beveled outward. The number, shape and position of the holes can be varied. This embodiment is ideal, for example, for ice cream toppings and salad dressings and other viscous food products. In a preferred embodiment, this bottle is a unitary structure including the novel flange top. Finally, FIGS. 31 and 31a illustrate yet another nozzle embodiment. In this embodiment, the nozzle/spreader comprises a wide but narrow slit flange 1100 which is affixed to the bottle or tube 1101. The corners of the nozzle can be straight or cornered. This embodiment may include an internal support or stilt 1102 to prevent the nozzle from collapsing. In view of the foregoing disclosure, some advantages of the present invention can be seen. For example, a novel spreader has been disclosed. The novel spreader easily, quickly and accurately spreads material such as edible substances, being dispensed from containers such as squeeze tubes or bottles. Referring to FIGS. 32a to 32c, alternative embodiments of the spreader dispenser of this present invention for viscous materials, salad dressings, mustard, ketchup, taco sauce, ice cream toppings, syrups and other semi-liquid and squeezable products. As seen in FIGS. 32a and 32b, the invention includes a bottle of food product 1202 containing a dome-shaped spreader/applicator 1210. The dome-shaped spreader/applicator 1210 has an outer lip 1212 which snaps onto the container neck to hold it secure. The dome-shaped spreader 1210 has a plurality of apertures or orifices 1220 which are position angle outward so that the dispensed product spreads out evenly when applied. The dome application thus functions to spread out the food product in a wide array and with uniformity. The orifices 1220 of the dome 1210 can be straight (in line) (FIG. 32c) or may be dispensed over the body of the dome 1225. In one embodiment the dome-shaped spreader 1210 may have internal threads 1230, which enables the lid to securely attach to the top of the bottle by screwing it on, snapping it on, or alternatively by affixing it by any other mechanism or instrumentality. Referring to FIGS. 33a and 33b, the orifice's dome-shaped spreader 1220 may have slits 1229 or a plurality of cross-slits 1231 instead of fully open apertures or orifices. It is to be appreciated that the holes where the product emerges, can have a plurality of diameters or shapes and any geometric configuration. Referring to FIGS. 34a and 34b, an embodiment is illustrated in which the dome-shaped spreader/applicator 1210 is placed within the inside lip of the bottle 1240. The spreader/applicator is held in place by a number of mechanisms, including threads or snaps. The dome in this embodiment fits proximate to the bottle top and has an annular serrated ridge 1354 which fits on the inside of the bottle. The dome can also be screwed into the bottle or secured using a variety of mechanical attachment systems. FIGS. 35a-35e illustrate caps 1300 which fit over the dome-shaped spreader. The present invention displays a number of cap embodiments. As shown in FIG. 35a, a first cap embodiment comprises a dome-shaped nozzle cap which is attached by a living hinge 1318. It can also be separate from the bottle. As shown in FIG. 35e, the cap can comprise a male closure with matching prongs 1323 which cover over the orifices. This prevents clogging of the holes by dried product. FIGS. 36a to 36c illustrate an embodiment of the dome-shaped nozzle applicator 1360 which corresponds to the wide flange embodiment of FIG. 30. Here the oval-shaped applicator 1360 is dome-shaped and a corresponding cap is dome-shaped and is designed to fit on the bottle. The dome can fit inside or outside of the bottle as shown in FIGURES. Alternatively, the dome-shaped applicator 1360 can have slits, crosses or other aperture shapes 1362 as shown in FIG. 36c. FIGS. 37(a)-(f) illustrates yet a further embodiment of the present invention. In this embodiment the dome-shaped applicator has a rotating dial cover 1372 which permits the apertures or orifices 1220 to be selectively opened and closed. By rotating the dial in one direction the orifices are open and product can flow. When rotated in the other direction the orifices 1220 are closed. The orifices can have any shape, size or configuration. FIG. 38 illustrates a dome having a plurality of orifices having different shapes, sizes and orientation. The different sized orifices 1220 allow the passage of different sized chunks or pieces (e.g. “Thousand Island” salad dressing). FIG. 39 illustrates yet another embodiment of the invention in which the applicator has the shape of a flattened, four sided pyramid 1380 instead of a curved shape. Each side 1382 has a plurality of orifices 1384. It is to be noted that the pyramid embodiment can have more than four sides (e.g. 6,8, 10, etc.). The invention also suggests additional embodiments besides pyramid shapes. FIG. 40 is an embodiment which corresponds with the nozzle embodiment of FIG. 28. In this embodiment, the dome-shaped applicator is affixed to the end of the cylindrical nozzle casing and permits product to flow through the orifices 1220. Referring to FIGS. 41a to 41c, alternative orifice configurations are shown. The orifices can be indented 1390 into the bottle. They can also face or protrude outward 1394. They can be contiguous with the dome 1396. The strength and pliability of the plastic, impacts the types of food to be used and the amount of pressure that needs to be applied. Referring now to FIGS. 42a and 42b, a still further embodiment is shown and described. This embodiment comprises an applicator with a plurality of nipple openings 1400. The embodiment comprises a plurality of flexible nipple inserts 1410. The flexible nipple inserts 1410 are indented inwardly 1420 into the bottle and they are forced outwardly 1425 when the product is squeezed out. FIGS. 43a to 43e shows a number of dome-shaped embodiments which illustrate the use of nipples. The nipples are shown as having a cross or X-shaped orifices 1500 as well as slits 1510. The nipple embodiment can be utilized with any of the embodiments shown in FIGS. 1 to 31. FIG. 44 illustrates an embodiment of the present invention in which the orifices are angled 1520. This embodiment permits product to be dispensed in a wide variety of directions. Finally, FIGS. 45a and 45b illustrate another embodiment in which the applicator 1600 has two sets of orifices. A four-holed dial 1610 can then be rotationally affixed over the applicator 1620. When the dial is turned in a first direction, the large orifices 1630 align with the dial. When turned in a second direction, the small orifices 1635 align. A third position closes the orifices. This embodiment facilitates two levels of product application flow. While the preferred embodiment of the present invention has been described and illustrated, modifications may be made by one of ordinary skill in the art without departing from the scope and spirit of the invention as defined in the appended claims. For example, in a preferred embodiment of the present invention, the bags 410 and 540 may be polybags, however, the bags may be of any type known to one of ordinary skill in art. Additionally, the method of securing the nozzles to the containers has been described and illustrated as being via a threaded engagement. However, a skilled artisan may employ any appropriate means to attach the nozzles to the containers, such as, but not limited to, a snap connection or molded piece. In addition, while the invention has been principally described in the context of food, it is to be appreciated that the applicator and spreader of the present invention may be applicable to non-food products. Nonexclusive examples include caulks, pastes, glues and building materials and automotive products such as waxes, greases, etc. | <SOH> BACKGROUND OF THE INVENTION <EOH>Spreadable foods are common table items and are enjoyed by many all over the world. There are numerous types of foods that can be spread. Typical spreadable foods include peanut butter, frosting, butter, mayonnaise, jelly, ice cream toppings, salad dressing and cream cheese and other edible spreads for use on bread, crackers, and the like. Often, a butter knife, spatula, or other similar device is used to spread the food onto the bread, cracker, or other item. However, these utensils can become lost on or at outdoor celebrations and picnics, or other events, or need to repeatedly dip a spreader knife into a jar. Additionally, material accumulates on the knife and jar edges, as well as crumbs of other materials can accumulate in the jar. A number of patents have issued related to food dispensers and the like. U.S. Pat. No. 5,377,874 discloses a liquid dispenser for dispensing fluid condiment materials, such as ketchup, mustard and mayonnaise as well as other liquids such as medicated salves, lotions and ointments. The dispenser includes a tubular body with a spherical plunger element connected to a spreader paddle member disposed within a tubular body. Upon external manipulation of the tubular body, the spherical plunger and spreader paddle arrangement is urged toward a dispenser nozzle for release of condiment filling contained therein. The sanitary spreader paddle simultaneously protrudes from within the tubular body as condiment filling is being evacuated. As a result, the user may evacuate the entire volume of condiment filling within the dispenser as well as spread the deposited condiment filling on a food article to be eaten. In a medical application of the invention, the dispenser includes an integral applicator swab which is connected to the spreader paddle and resides within the plunger. The spreader paddle is separated from the plunger to expose the cleansing swab for use on the body. U.S. Pat. No. 5,330,075 is directed to a food condiment dispenser for dispensing fluid condiment materials, such as ketchup, mustard and mayonnaise. The dispenser includes a tubular body with a spherical plunger element connected to a spreader paddle member disposed within a tubular body. Upon external manipulation of the tubular body, the spherical plunger and spreader paddle arrangement is urged toward a dispenser nozzle for release of condiment filling contained therein. The sanitary spreader paddle simultaneously protrudes from within the tubular body as condiment filling is being evacuated. As a result, the user may evacuate the entire volume of condiment filling within the dispenser as well as spread the deposited condiment filling on a food article to be eaten. U.S. Pat. No. 4,957,226 is directed to an automatic food dispensing method, apparatus and utensil primarily for use in fast food restaurants, bakeries, and the like. The method and apparatus comprise a pumping system from a supply through a pump in a controlled amount with a reverse action of the pump after the appropriate amount has been dispensed in order to avoid it dripping. Other drip proof arrangements, such as valving are also utilized optionally. The utensil comprises a handle attached to a container and spreading utensil such as a spoon, ladle, or the like, wherein predetermined portions of a food or substance used in a food may be dispensed either continually or as predetermined quantities. The device consists of a spoon or other appropriately shaped utensil attached to a hollow handle which terminates in a non-interfering connection with the interior of the utensil at one end and terminates at the other end in a connection to a food supply source. U.S. Pat. No. 6,153,238 is directed to a packaged cheese product comprising a hermetically sealed container, preferably a pouch, made out of flexible material; a decorator tip or adaptor therefore inside the container, a cheese product inside the container and a cap for closing the decorator tip when the pouch is partially emptied. The cheese product can be extruded after cuffing the corner off of the pouch and seating the decorator tip in the resulting opening. Cheese in decorative shapes can then be easily applied as a garnish on food items and the pouch can then be re-closed by capping the decorator tip. The cap preferably has a bulb member that fits inside the decorator tip and a skirt member that fits around the outside petals of the preferred decorator tip. U.S. Pat. No. 4,844,917 is directed to a cake frosting technique and assembly including a disposable frosting bag for home or commercial use to render the frosting or decorating of cakes or other pastries more convenient and expeditious by the complete elimination of the need for expensive and messy heretofore-used large commercial squeeze bags, or manually whipped and spread frosting, or expensive aerosols. The invention contemplates the ready coloring or tinting of the frosting to any desired hue within a wide range with any particular color and further contemplates the imparting of any desired flavoring to the frosting by the separate and conveniently associated provision of the aforesaid disposable bag containing a neutral or white frosting along with a plurality of separate color tint tubes and a plurality of separate flavor taste tubes, whose contents are to be admixed respectively with the base frosting material to achieve a desired blend for the ultimate decorative and taste effects contemplated. U.S. Patent Publication No. 2002/0000441 discloses an aperture forming structure, which when attached to or integrally formed in dispenser packages for flowable substances allows reclosure and single or multiple uses. The aperture forming structure includes a breakaway tip member of thermoformable plastic. The break away tip includes a hollow protrusion from a surface. The intersection of the hollow protrusion and the surface is a fault line. Rupturing of the fault line creates an aperture from which the contents of the dispenser package may exit. A cap may be integrally formed with the aperture forming structure and detached for protecting the hollow protrusion or for closing the aperture created when the fault line is ruptured. The aperture forming structure can be made by heating a relatively stiff substantially flat thermoformable sheet of and then stretching the sheet to create a first and a second hollow protrusion in a tiered configuration. A rupture line is placed at the intersection of the first and the second protrusions. The sheet may be attached to a pouch or containment member formed from a flexible sheet which contains any flowable substance. While there have been a number of prior systems directed to food spreaders, none have adequately addressed the need for ease of use and convenience. There is a need for a system to easily, quickly and accurately spread material such as edible substances, being dispensed from containers such as squeeze tubes or bottles. | <SOH> OBJECTS AND SUMMARY OF THE INVENTION <EOH>It is an object of the present invention to provide a spreader that will allow a user to spread a spreadable food item. It is a further object of the present invention to provide a spreader having a dispensing nozzle associated with the dispenser to dispense said material, and a spreader surface associated with the nozzle whereby the dispenser may be manipulated to cause the spreader surface to spread material dispensed via the nozzle. It is a further object of the present invention to provide a system in which the spreader is flexible and can be viewed in use. It is a further object to provide a spreader in which the spreader is dome-shaped. It is a further object of the present invention to provide a spreader which has a number of orifices, having different shapes and configurations, including dome shapes. It is yet another object of the present invention to provide a spreader which includes expandable nipples. It is yet a further object of the present invention to provide a spreader, including a container, having a base and a lid opposite the base, the container capable of holding a spreadable food item; a detachable handle mounted on the container; a plunger, adapted to engage the detachable handle such that when the detachable handle is depressed, the plunger exerts pressure on the spreadable food item in the container; and a dispenser nozzle, mounted on the exterior of the container proximate to the base of the container, in fluid communication with the interior of the container such that the spreadable food item may be forced through the dispenser nozzle, the dispenser nozzle capable of being in a first position or a second position. In accordance with a first aspect of the present invention, a novel spreader is disclosed. The novel spreader includes a dispensing nozzle associated with the dispenser to dispense said material, and a spreader surface associated with the nozzle whereby the dispenser may be manipulated to cause the spreader surface to spread material dispensed via the nozzle. In accordance with another aspect of the present invention, a novel spreader is disclosed. The novel spreader includes a container, having a closed end and an open end, capable of holding a spreadable food item, and a nozzle, mounted at the open end of the container, and having an opening in fluid communication with the open end of the container such that the spreadable food item can flow through the opening of the nozzle. In accordance with yet another aspect of the present invention, a novel spreader/dispenser is disclosed. The novel spreader/dispenser includes a container, having a base and a lid opposite the base, the container capable of holding a spreadable food item; a detachable handle mounted on the container; a plunger, adapted to engage the detachable handle such that when the detachable handle is depressed, the plunger exerts pressure on the spreadable food item in the container; and a dispenser nozzle, mounted on the exterior of the container proximate to the base of the container, in fluid communication with the interior of the container such that the spreadable food item may be forced through the dispenser nozzle, the dispenser nozzle capable of being in a first position or a second position. The nozzles of the present invention can be used to spread a large variety of items in a variety of formats. | 20040326 | 20080101 | 20070816 | 62225.0 | B05C1100 | 1 | WALCZAK, DAVID J | SPREADER | SMALL | 1 | CONT-ACCEPTED | B05C | 2,004 |
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10,810,782 | ACCEPTED | Game using secondary indicia providing game status information | In a method of playing a game, secondary indicia are used to provide information regarding game status. In one embodiment, a wagering game such as video keno, video slots or video poker is presented using one or more first indicia such as keno numbers, cards or slot symbols. Secondary indicia are displayed at one or more times to provide game state information such as information regarding win or loss, matching or un-matching symbols, correct or incorrect selections or the like. Preferably, the secondary indicia have one characteristic or attribute indicating one game state (such as a winning selection or outcome) and another characteristic indicating another game statue (such as a losing selection or outcome). One embodiment of the invention is a keno game in which secondary indicia are displayed to provide information regarding whether the player's selected numbers have matched or not. | 1. A method of playing a game of keno at a gaming device comprising the steps of: displaying a set of keno numbers; accepting input from a player regarding one or more player selected numbers from said keno numbers; displaying a set of game numbers; determining if one or more of said game numbers match one or more of said player selected numbers; displaying a secondary indicia in association with each player selected number, said secondary indicia associated with player selected numbers which were determined to match one of said game numbers having an attribute indicating a match and said secondary indicia associated with player selected numbers which were determined not to match one of said game numbers having an attribute indicating no match; and determining the outcome of said game. 2. The method in accordance with claim 1 wherein said set of secondary indicia are Smiley characters. 3. The method in accordance with claim 1 wherein said attribute indicating a match is animation of said secondary indicia to indicate happiness or celebration. 4. The method in accordance with claim 1 wherein said attribute indicating no match is animation of said secondary indicia to indicate unhappiness or loss. 5. The method in accordance with claim 1 wherein one or more of the secondary indicia differ from one another in appearance. 6. The method in accordance with claim 1 wherein a secondary indicia is displayed in physical proximity to each player selected number. 7. The method in accordance with claim 1 wherein said secondary indicia are other than numbers. 8. The method in accordance with claim 1 wherein said game is played as a wagering type game and including the step of accepting a wager from a player to play said game. 9. The method in accordance with claim 1 wherein said steps of displaying are performed on a video display of said gaming device. 10. A method of playing a game comprising the steps of: accepting a wager from a player; displaying at one or more times one or more first indicia in the play of a game; displaying at one or more times one or more second indicia, said secondary indicia having at least two attributes for providing information regarding at least two different game states of said game; and determining if the outcome of said game is a winning or losing result. 11. The method in accordance with claim 10 wherein said game is the game of keno. 12. The method in accordance with claim 10 wherein said game is the game of bingo. 13. The method in accordance with claim 10 wherein said secondary indicia comprise animated characters having mannerisms which provide said information. 14. The method in accordance with claim 10 wherein said characters comprise Smiley characters. 15. The method in accordance with claim 10 wherein said second indicia are displayed in physical proximity to one or more of said first indicia. | FIELD OF THE INVENTION The present invention relates to methods and apparatus for presenting games for play. BACKGROUND OF THE INVENTION Gaming continues to grow in popularity. Legalized wager-based gaming has expanded world-wide. As interest in gaming grows, so does the public's desire for new and exciting games. Various efforts have been made to make games more interesting. Newer games offer better sound and image effects to excite the player. For example, gaming machines may now play music and present video clips of movies. Newer games are commonly themed, with Playboy®, I Love Lucy®, Monopoly® and other gaming machines offering games which have attributes of these other well-known shows and games. Other games now offer “bonus” rounds. For example, based upon the outcome of a base game, a player may enter a bonus round where a wheel spins and the player is awarded a bonus win. The present invention is directed to a game which provided added excitement and pleasure to the gaming experience. SUMMARY OF THE INVENTION The present invention comprises a method of playing a game, and apparatus, such as a gaming device and/or system, for presenting the game of the invention. In one embodiment of a method of playing a game, secondary indicia are used to provide information regarding the status of the game. In one embodiment, a wagering game such as video keno, video slots or video poker is presented using one or more first indicia such as keno numbers, cards or slot symbols. Secondary indicia are displayed at one or more times to provide game state information such as information regarding win or loss, matching or un-matching symbols, correct or incorrect selections or the like. Preferably, the secondary indicia have one characteristic or attribute indicating one game state (such as a winning selection) and another characteristic indicating another game statue (such as a losing selection). The secondary indicia may be of a variety of types, have various forms, and be displayed at various times during play of the game. In one embodiment, the secondary indicia are “Smiley” indicia (e.g. of the type ). In a preferred embodiment, the characteristics of the secondary indicia which convey game state may comprise the image of the indicia or animation of the indicia conveying mood, such as celebration or happiness, or sadness or loss. One preferred embodiment of the invention is a game of keno. First indicia comprising keno numbers, such as the numbers 1-80, are displayed. In one embodiment, the numbers are displayed in a keno number grid. A player selects one or more of the numbers as player selected numbers. A set of game numbers are generated and displayed. In accordance with the game, it is determined if any of the game numbers match any of the player selected numbers. Preferably, if a player selected number was matched, then a secondary indicia is displayed which provides information regarding the match. If a player selected number was not matched, then a secondary indicia is preferably displayed which provides information that the number was not matched. In one embodiment, the secondary indicia comprise animated Smiley characters. The characters which are associated with matching numbers are convey celebration and win, while those which are associated with non-matching numbers convey loss. Preferably, the secondary indicia are displayed physically proximate the player selected numbers. The game of the invention may be implemented in a variety of manners. In one embodiment, the game of the invention is presented at a gaming machine which includes a video display for displaying the first indicia used to play the game and the secondary indicia for conveying game state information. Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures. DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a gaming device of the type which may be used to implement a game in accordance with the invention for play by a player; FIG. 2 illustrates the display of numbers utilized to play a game of keno in accordance with an embodiment of the invention with player selected numbers displayed; FIG. 3 illustrates the generation and display of game numbers for play of the game; FIG. 4 further illustrates the display of game numbers which are compared to the player selected numbers as well as the display of secondary indicia in accordance with the invention; and FIG. 5 illustrates the result of a game of keno in accordance with the invention in which secondary indicia are displayed, the secondary indicia providing game state information pertaining to whether the player selected numbers matched the game name numbers. DETAILED DESCRIPTION OF THE INVENTION The invention is a method of playing a game. In the following description, numerous specific details are set forth in order to provide a more thorough description of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention. In general, the invention comprises a method of playing a game and an apparatus for presenting a game. In one or more embodiments of the invention, a game is played using a first set of indicia. The game may be, for example, a game of video keno, bingo or poker. One or more secondary indicia are used to provide information regarding a state of the game, such as the outcome of the game. In a preferred embodiment, the secondary indicia have a plurality of conditions, with the condition of the second indicia providing game state information. In a preferred embodiment, the game is presented to a player with a gaming machine. FIG. 1 illustrates a gaming machine 20 in accordance with one embodiment of the invention. As illustrated, the gaming machine 20 includes a housing 22 for enclosing/supporting various components of the gaming machine. The gaming machine 20 includes a display 24 for displaying information, such as game indicia. In one embodiment, the display 24 is a video type display, such as a CRT, LCD, plasma or other display. Speakers (not shown) or other devices may be provided for generating sound associated with the game. In one embodiment, the game may be played as a wager-type game which requires that a player place a bet or wager to play the game. Preferably, if the player is a winner of the game, then the player is provided an award, such as a monetary payout (such as coins) or other prizes. As illustrated, the gaming machine 20 may include a bill validator/acceptor 26 for accepting paper currency and a coin acceptor 28 for accepting coins. Other means of payment, such as a credit card reader, may be provided. An award of winnings in the form of coins may be paid to the player via a coin tray 30. Preferably, the gaming machine 20 includes means for a player to provide input. In one embodiment, this means comprises one or more buttons. For example, a plurality of card “hold” or “select” buttons 32 may be provided for permitting a player to hold/select cards in a hand. A deal/draw button 34 permits a player to indicate that he/she wishes the game to start or to draw replacement cards. A bet button 36 is provided for a player to select the amount to bet on a particular game. In one embodiment, a display of the gaming machine 20 may permit touch or similar direct input thereto. A game controller (not shown) is provided for controlling the various devices of the gaming machine and for providing game information. For example, the game controller may be arranged to generate video and audio data for presentation by the display and speakers of the gaming machine 20. The game controller may be arranged to detect a signal from the coin acceptor indicating the receipt of coins, and may be arranged to cause a coin delivery mechanism to deliver coins from a coin hopper to the coin tray 30. It will be appreciated that the gaming machine 20 may have a variety of configurations, and that the gaming machine 20 illustrated and described above is but an example of a device for implementing the game of the present invention. In one or more embodiments, the gaming machine 20 may be associated with a network and receive game information remotely and may transmit information, such as payout and game play information, to a remote location. A specific version of a game of the invention will be described with reference to FIGS. 2-5 to aid in understanding the invention. Additional aspects of the invention will be described below, it being understood that the invention is not limited to the configuration illustrated in FIGS. 2-5 and now described. In accordance with the invention, a game is presented to a player for play. In the embodiment illustrated in FIG. 2, the game is the game of keno. In this embodiment, the game is presented via the display of a gaming machine, such as the gaming machine illustrated in FIG. 1. As illustrated, the game is played using a first set of indicia 120. In this embodiment, the indicia 120 comprise the numbers 1-80. In this embodiment, the numbers are illustrated in grid-format as is known in the art of the keno game. As illustrated, various additional information may be displayed to the player, such as information identifying the game being played and a paytable 122. The paytable 122 preferably provides information regarding winning amounts paid or awarded for particular winning combinations based upon the player's wager. Of course other or additional information may be displayed such as the rules or instructions of the game. In the game of keno, a player selects one or more numbers from the set of numbers, in an attempt to match the selected numbers against a set of game numbers. As also illustrated in FIG. 1, the player may make selections of the numbers via an input, such as by touch-input to the display which is displaying the numbers. The particular number of numbers which are selected may vary depending upon the rules of the game and/or player desire. For example, the player may often be permitted to select as few as 1 and as many as 20 numbers in normal keno games. In this embodiment, the player has selected 7 numbers, numbers 1, 4, 13, 27, 43, 56 and 80. In the game of keno, a set of game indicia are selected. The game indicia comprise a set of randomly selected numbers from the set of keno numbers (e.g. selected from the numbers 1-80). The number of game indicia which are selected may vary. In one embodiment, 20 numbers are selected. FIGS. 2 and 3 illustrate one embodiment of a method of displaying and/or selecting the numbers. As illustrated, an animated event is utilized to display the selected numbers. In one embodiment, the animated event comprises “parachuters” 124 exiting an overflying airplane 126. As illustrated in FIG. 4, these parachuters 124 float downwardly from the top towards the bottom of the display. As they do so, they open their parachutes, each revealing one of the game numbers 128 for that game. In one embodiment, the game numbers 128 are “deposited” in game number spaces adjacent the displayed game board. It will be appreciated that the game numbers may be generated and displayed in a variety of fashions. The game numbers may be generated using a random number generator, such as located at the gaming machine. The game numbers may simply be displayed in positions or, as illustrated, displayed as part of an animated sequence which adds interest and excitement to the game. As is known in the game of keno, the outcome of the game is determined by comparing the player selected numbers to the game numbers. If a minimum number of matches has resulted, then the player may be declared a winner. A payout or other award may be provided to the player for such a result. In accordance with the invention, game state information is provided by secondary indicia 130. The secondary indicia may be referred to as secondary elements, displays or by other terminology. In the embodiment illustrated in FIGS. 4 and 5, the secondary indicia 130 comprise “Smiley” characters. These characters may have a wide variety of forms, such as and . In this embodiment, when a player selected number matches a game number 128, then a secondary indicia 130 preferably identifies that match. As illustrated in FIG. 4, the game numbers “56” and “80” have been displayed. These numbers match the same numbers selected by the player. As a result, secondary indicia 130 in the form of Smiley characters are displayed. Preferably, the secondary indicia 130 are displayed at or adjacent the player's matching number (i.e. in physical proximity as viewed by the player). This provides an indication to the player that a match has occurred. In a preferred embodiment, the nature, state, condition, appearance or the like of the secondary indicia is used to indicate different game state information. As illustrated in FIG. 4, in the event of a match, the Smiley characters show a happy, winning or celebratory condition. Referring to FIG. 5, after all the game numbers 128 have been selected and displayed, it is known whether certain of the player selected numbers were not matched. In the game illustrated, the player selected numbers “13” and “43,” for example, were not selected. Preferably, secondary indicia 130 are used to identify or convey such to the player. These secondary indicia 130 preferably convey a different game state than those used to identify matches. In the embodiment illustrated, the secondary indicia 130 comprise Smiley characters which are sad, mad, frustrated or the like. This embodiment game has a “Smiley” theme, in that the secondary indicia used to convey game state information apart from the first indicia used to play the game, are “Smiley” characters. As indicated, these characters may have a variety of forms and, most preferably, are capable of conveying “meaning” as to the condition or state of the game, such as a winning or positive outcome, and a losing or negative outcome. The method of the invention will now be described in additional detail. In accordance with the method, a game is presented to a player. In one embodiment, the game is a wagering type game. In this embodiment, the player places a wager, such as win coins, currency, credits or other means now known or later developed. Preferably, in such a game format, the player is awarded winnings, such as monies, credits, prizes or the like, depending upon the outcome of the game. The particular game which is presented, including the various steps of the play of the game, may vary. In a preferred embodiment, the game is presented on a video-type gaming machine, thus allowing for the simple generation and display of the secondary indicia. For example, the game may be the game of keno, bingo, poker, slots or the like, as presented on video-type gaming machine. Of course, the game may be any of the wide variety of games now known or later developed. The game is preferably presented to the player at a gaming machine such as described above. Of course, the game could be presented using a variety of devices and systems. For example, the game could be presented to a player at a terminal of a gaming system including a remote server or servers which generate game information for presentation at the terminal. Depending upon the particular game, various player inputs may be received. These inputs may include a wager, selection of indicia, such as cards to be held, keno numbers which are selected at the like. As indicated, these inputs may be accepted in a variety of fashions, such as with buttons, through a touch-screen or the like. Of course, the player may be permitted to select the game they wish to play. For example, the gaming machine may present a menu of games for selection by the player. Preferably, the game is played using one or more first indicia. The first indicia may also be referred to as game indicia or other terminology. The first indicia may depend upon the particular game which is presented. For example, in the game of keno, the first indicia may comprise the numbers 1-80. In the game of poker, the first indicia comprise cards, such as the 52 cards corresponding to a standard deck of playing cards. The first indicia might, in that case, also include Jokers or the like. It is appreciated that there may be a variety of first indicia, such as numbers on cards and numbered balls in the game of bingo, or a great variety of indicia in the game of slots. In all cases, however, one or more indicia are used to present and play the game. In accordance with the invention, secondary indicia are used to indicate game state or condition. The various forms of the secondary indicia, and when and how they are displayed or presented may vary. Most preferably, the secondary indicia are different from the first indicia, and do not comprise any of the first indicia or variations thereof. In this manner, the secondary indicia are readily identifiable by the player as being separate from the indicia which are actually being used to play the game itself. As will be appreciated, various games may have different states or conditions. These states may correspond to stages of the game, winning and losing selections, winning and losing outcomes, and other events. For example, in the case of the game of keno, as described, the state of the game may include whether particular player selected numbers matched or did not match the selected game numbers. In the game of video poker, the state of the game may include whether particular cards comprise a predetermined winning combination of cards. In the case of bingo, the state of the game may include whether or not certain matching indicia comprise a winning pattern. The secondary indicia need not be displayed in conjunction with every game state. For example, in the case of video poker, secondary game indicia may not be displayed during the initial display of dealt cards and the selection of held cards. The secondary indicia may be displayed, however, in association with the cards of the resulting or final hand. Of course, the secondary indicia could be displayed at more than one time (i.e. at more than one game stage/state). For example, in the game of video poker, secondary indicia could be displayed in association with selected or held cards, and then again in association with the resulting hand. In the game of bingo, secondary indicia could be displayed when a match is received, as well as in the event a bingo or “matching patten” has resulted. The secondary indicia which are displayed may vary. As described, in a preferred embodiment, the secondary indicia are configured to convey information to the player regarding the game state, such as a positive or negative outcome or result or the like. As a result, the appearance of the indicia, its size, shape, motion or other attribute is preferably selected to provide such information. The particular attribute of the secondary indicia is preferably selected to be detected by the player through observation. In one embodiment, the secondary indicia may be animated, with the mannerisms, portrayed “mood” or other actions conveying the desired information. As described, in one embodiment, the secondary indicia comprise Smiley characters. These characters have the advantage that they are readily recognized and, because they have a “face,” imparted facial expression is useful in conveying information to the player. Of course, the secondary indicia could comprise a wide variety of other elements or characters. For example, the secondary indicia could comprise images of animals, such as dogs or cats. The indicia could comprise animated human forms or inanimate objects. The secondary indicia also need not comprise indicia all of the same type or theme. In one embodiment, the secondary indicia may include textual information and may include animation of events. For example, the secondary indicia could include textual information regarding win, loss or the like. The secondary indicia could comprise animated events such as winning or losing celebration information. The secondary indicia may be displayed or presented in a variety of manners. In a preferred embodiment, secondary indicia are associated with the first or primary indicia. For example, in the game of keno described above, secondary indicia are associated with player selected first indicia to provide information regarding whether the player's selections were matching. In the case of video poker, the secondary indicia could be associated with individual displayed cards. In the case of bingo, the secondary indicia could be associated with selected numbers/balls, or with game indicia displayed on a player's game card or the like. At the conclusion of game play, a winning or losing result may be declared. A player may be paid winnings, credits, prizes or the like in the event the outcome of the game is a winning outcome. In one embodiment, the secondary indicia may change over time or change depending as the game state changes. For example, in the game of keno, secondary indicia may be displayed in conjunction with each player selected number as each number is selected. In one embodiment, at this time the indicia may comprise an image of a Smiley face showing a happy face or mood. As the game numbers are selected and matches are determined, the state of the secondary indicia may change to reflect the new game state. For example, if a player selected number is matched, the secondary indicia associated with that number may be animated in a celebratory format or action. Other the other hand, the secondary indicia associated with non-matching numbers may be change to images of unhappy or sad characters or animated to show loss, sadness or the like. The invention has numerous advantages. First and foremost, the invention has the advantage of adding excitement to the play of game. For example, in the game of keno, normally a simple grid of numbers is displayed, a player makes selections, and the game numbers are displayed. Matches are determined. As presented on a video display, this method of game play lacks any visual excitement. The use of secondary indicia in accordance with the invention adds a great deal of visual stimulation to the play of the game. More importantly, the secondary indicia provide information to the player. The secondary indicia provide game state information apart from the first indicia which are actually used to present the game. Further, the secondary indicia have, as described above, various forms or conditions for indicating different game states. For example, in the case of the game of video keno, the secondary indicia may be associated with the first or primary indicia to provide information to the player as to whether the player selected numbers were matched or not. This avoids, for example, the player having to compare each of their selections on the grid to the selected game numbers. Instead, the player can simply and easily view just the grid and determine by the secondary indicia whether the selected number was matched or was not matched. It will be understood that the above described arrangements of apparatus and the method therefrom are merely illustrative of applications of the principles of this invention and many other embodiments and modifications may be made without departing from the spirit and scope of the invention as defined in the claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>Gaming continues to grow in popularity. Legalized wager-based gaming has expanded world-wide. As interest in gaming grows, so does the public's desire for new and exciting games. Various efforts have been made to make games more interesting. Newer games offer better sound and image effects to excite the player. For example, gaming machines may now play music and present video clips of movies. Newer games are commonly themed, with Playboy®, I Love Lucy®, Monopoly® and other gaming machines offering games which have attributes of these other well-known shows and games. Other games now offer “bonus” rounds. For example, based upon the outcome of a base game, a player may enter a bonus round where a wheel spins and the player is awarded a bonus win. The present invention is directed to a game which provided added excitement and pleasure to the gaming experience. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention comprises a method of playing a game, and apparatus, such as a gaming device and/or system, for presenting the game of the invention. In one embodiment of a method of playing a game, secondary indicia are used to provide information regarding the status of the game. In one embodiment, a wagering game such as video keno, video slots or video poker is presented using one or more first indicia such as keno numbers, cards or slot symbols. Secondary indicia are displayed at one or more times to provide game state information such as information regarding win or loss, matching or un-matching symbols, correct or incorrect selections or the like. Preferably, the secondary indicia have one characteristic or attribute indicating one game state (such as a winning selection) and another characteristic indicating another game statue (such as a losing selection). The secondary indicia may be of a variety of types, have various forms, and be displayed at various times during play of the game. In one embodiment, the secondary indicia are “Smiley” indicia (e.g. of the type ). In a preferred embodiment, the characteristics of the secondary indicia which convey game state may comprise the image of the indicia or animation of the indicia conveying mood, such as celebration or happiness, or sadness or loss. One preferred embodiment of the invention is a game of keno. First indicia comprising keno numbers, such as the numbers 1-80, are displayed. In one embodiment, the numbers are displayed in a keno number grid. A player selects one or more of the numbers as player selected numbers. A set of game numbers are generated and displayed. In accordance with the game, it is determined if any of the game numbers match any of the player selected numbers. Preferably, if a player selected number was matched, then a secondary indicia is displayed which provides information regarding the match. If a player selected number was not matched, then a secondary indicia is preferably displayed which provides information that the number was not matched. In one embodiment, the secondary indicia comprise animated Smiley characters. The characters which are associated with matching numbers are convey celebration and win, while those which are associated with non-matching numbers convey loss. Preferably, the secondary indicia are displayed physically proximate the player selected numbers. The game of the invention may be implemented in a variety of manners. In one embodiment, the game of the invention is presented at a gaming machine which includes a video display for displaying the first indicia used to play the game and the secondary indicia for conveying game state information. Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures. | 20040326 | 20121218 | 20050929 | 83113.0 | 0 | LIDDLE, JAY TRENT | GAME USING SECONDARY INDICIA PROVIDING GAME STATUS INFORMATION | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,810,799 | ACCEPTED | Method for the purification of piribedil | A method for purifying Piribedil includes mixing Piribedil solid having a purity of 98% by weight with water, boiling the mixture, adding slowly 95% ethanol to the boiling mixture to form a clear liquid, filtering the hot clear liquid, cooling the filtrate to obtain a white crystal having a purity of 99.8% by weight of Piribedil. | 1. A method for purifying Piribedil comprising the following steps: a) mixing a Piribedil product having a Piribedil purity of 98 wt % or lower with water; b) heating the resulting mixture to boiling or a temperature near boiling; c) adding ethanol to the hot mixture from step b) while maintaining a temperature of the resulting mixture at 60-100° C., so that a clear liquid is obtained; d) filtering the hot clear liquid; e) cooling the resulting filtrate to form a crystal therein; and f) removing the crystal from the filtrate and drying the crystal to obtain a white solid having a Piribedil purity higher than 98 wt %. 2. The method according to claim 1, wherein the Piribedil product having a Piribedil purity of 98 wt % or lower used in step a) has a Piribedil purity of about 98 wt %. 3. The method according to claim 1, wherein in step a) the Piribedil product having a Piribedil purity of 98 wt % or lower is mixed with water in a ratio of per kilogram of the Piribedil product 0.1-10 liters of water. 4. The method according to claim 3, wherein in step a) the Piribedil product having a Piribedil purity of 98 wt % or lower is mixed with water in a ratio of per kilogram of the Piribedil product about one liter of water. 5. The method according to claim 2, wherein in step a) the Piribedil product having a Piribedil purity of 98 wt % is prepared from a method comprising reacting 1-(2-pyrimidinyl)piperazine and piperonal in the presence of formic acid as a reducing agent at a temperature of 100-140° C. 6. The method according to claim 1, wherein the ethanol used in step c) is an aqueous solution having an ethanol concentration of 25-100 wt %. 7. The method according to claim 1, wherein the ethanol used in step c) is an aqueous solution having an ethanol concentration of 95 wt %. 8. The method according to claim 7, wherein in step c) the ethanol added is in an amount of 1-100 liters per kilogram of the Piribedil product. 9. The method according to claim 8, wherein in step c) the ethanol added is in an amount of 10 liters per kilogram of the Piribedil product. 10. The method according to claim 1, wherein the white solid obtained in step f) has a Piribedil purity of 99.8 wt %. | FIELD OF THE INVENTION The present invention is related to a method for purifying 2-[1′(3″,4″-methylenedioxy benzyl)-4-piperazinyl]-pyrimidine, which is also known as Piribedil, and in particular to a method for purifying Piribedil from a purity of 98 wt % or lower to 99.8 wt %. BACKGROUND OF THE INVENTION Piribedil is 2-[1′(3″,4″-methylenedioxy benzyl)-4-piperazinyl]-pyrimidine, and its chemical structure is as follows: According to the disclosures in U.S. Pat. Nos. 3,299,067 (1967) and 5,362,731 (1994), and Polish patent No. PL 167397 (1995), Piribedil is useful in treating a patient suffering Parkinson's disease or hyperactive bladder, and it can also be used as a peripheral vasodilator, analgesic agent or anti-inflammatory agent. Polish patent No. PL 167397 (1995) discloses a method of the synthesis of Piribedil comprising reacting 1-(2-pyrimidinyl)piperazine and piperonal in the presence of a reducing agent, formic acid, at a temperature of 100-140° C. The reaction can be represented by the following equation: This synthesis method is recognized as the simplest method for the preparation of Piribedil. However, the Piribedil product prepared by this method is a light yellow powder having a purity of 98 wt %. The inventors of the present application have made an approach to purify this Piribedil product including adding this Piribedil product into anhydrous ethanol or 95 wt % ethanol, boiling the resulting mixture, and re-crystallizing. The re-crystallized Piribedil product becomes darker in color and lower in purity. Another approach made is similar to the first approach but further includes a de-coloring step with activated carbon before the re-crystallization. However, the Piribedil purity is not enhanced. Therefore, there is a need in the industry for a method of the purification of Piribedil, which can increase the purity of the Piribedil product from 98 wt % to a higher purity. SUMMARY OF THE INVENTION The present invention provides a method for purifying Piribedil comprising the following steps: a) mixing a Piribedil product having a Piribedil purity of 98 wt % or lower with water; b) heating the resulting mixture to boiling or a temperature near boiling; c) adding ethanol to the hot mixture from step b) while maintaining a temperature of the resulting mixture at 60-100° C., so that a clear liquid is obtained; d) filtering the hot clear liquid; e) cooling the resulting filtrate to form a crystal therein; and f) removing the crystal from the filtrate and drying the crystal to obtain a white solid having a Piribedil purity higher than 98 wt %. Preferably, the Piribedil product having a Piribedil purity of 98 wt % or lower used in step a) has a Piribedil purity of 98 wt %. Preferably, in step a) the Piribedil product having a Piribedil purity of 98 wt % or lower is mixed with water in a ratio of per kilogram of the Piribedil product 0.1-10 liters of water, and more preferably about one liter of water. Preferably, the Piribedil product having a Piribedil purity of 98 wt % or lower is prepared from a method comprising reacting 1-(2-pyrimidinyl)piperazine and piperonal in the presence of formic acid as a reducing agent at a temperature of 100-140° C. Preferably, the ethanol used in step c) is an aqueous solution having an ethanol concentration of 25-100 wt %, and more preferably 95 wt % ethanol aqueous solution. Preferably, in step c) the ethanol added is in an amount of 1-100 liters, and more preferably 10 liters, per kilogram of the Piribedil product. Preferably, the white solid obtained in step f) has a Piribedil purity of 99.8 wt %. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The Piribedil purification method disclosed in the invention of the present application will be better understood by the following example, which is merely for illustration, not for the limitation of the scope of the present invention. EXAMPLE 1 To 1 kg powder having a Piribedil purity of 98 wt % in a 15 L flask equipped with a heating pack and mechanical stirrer one liter of distilled water was added. The mixture was heated to 100° C. Five liters of 95 wt % ethanol aqueous solution was slowly added into the flask while stirring, and the temperature of the mixture contained in the flask was dropped to about 60° C. upon completion of the 95 wt % ethanol. The temperature was increased to 75° C. by heating, and another five liters of 95 wt % ethanol aqueous solution was slowly added into the flask while maintaining the temperature at 75° C. by heating, thereby the opaque mixture was turned into a clear liquid. The hot clear liquid was filtered, and the resulting hot filtrate was cooled with an ice bath, so that a crystal was formed therein. The crystal was recovered by filtration and dried in vacuo to obtain 0.92 kilogram of a white crystallized solid having a Piribedil purity of 99.8 wt %. The Piribedil purity of 99.8 wt % was determined by differential scanning calorimetry (DSC) and high performance liquid chromatography (HPLC). | <SOH> BACKGROUND OF THE INVENTION <EOH>Piribedil is 2-[1′(3″,4″-methylenedioxy benzyl)-4-piperazinyl]-pyrimidine, and its chemical structure is as follows: According to the disclosures in U.S. Pat. Nos. 3,299,067 (1967) and 5,362,731 (1994), and Polish patent No. PL 167397 (1995), Piribedil is useful in treating a patient suffering Parkinson's disease or hyperactive bladder, and it can also be used as a peripheral vasodilator, analgesic agent or anti-inflammatory agent. Polish patent No. PL 167397 (1995) discloses a method of the synthesis of Piribedil comprising reacting 1-(2-pyrimidinyl)piperazine and piperonal in the presence of a reducing agent, formic acid, at a temperature of 100-140° C. The reaction can be represented by the following equation: This synthesis method is recognized as the simplest method for the preparation of Piribedil. However, the Piribedil product prepared by this method is a light yellow powder having a purity of 98 wt %. The inventors of the present application have made an approach to purify this Piribedil product including adding this Piribedil product into anhydrous ethanol or 95 wt % ethanol, boiling the resulting mixture, and re-crystallizing. The re-crystallized Piribedil product becomes darker in color and lower in purity. Another approach made is similar to the first approach but further includes a de-coloring step with activated carbon before the re-crystallization. However, the Piribedil purity is not enhanced. Therefore, there is a need in the industry for a method of the purification of Piribedil, which can increase the purity of the Piribedil product from 98 wt % to a higher purity. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a method for purifying Piribedil comprising the following steps: a) mixing a Piribedil product having a Piribedil purity of 98 wt % or lower with water; b) heating the resulting mixture to boiling or a temperature near boiling; c) adding ethanol to the hot mixture from step b) while maintaining a temperature of the resulting mixture at 60-100° C., so that a clear liquid is obtained; d) filtering the hot clear liquid; e) cooling the resulting filtrate to form a crystal therein; and f) removing the crystal from the filtrate and drying the crystal to obtain a white solid having a Piribedil purity higher than 98 wt %. Preferably, the Piribedil product having a Piribedil purity of 98 wt % or lower used in step a) has a Piribedil purity of 98 wt %. Preferably, in step a) the Piribedil product having a Piribedil purity of 98 wt % or lower is mixed with water in a ratio of per kilogram of the Piribedil product 0.1-10 liters of water, and more preferably about one liter of water. Preferably, the Piribedil product having a Piribedil purity of 98 wt % or lower is prepared from a method comprising reacting 1-(2-pyrimidinyl)piperazine and piperonal in the presence of formic acid as a reducing agent at a temperature of 100-140° C. Preferably, the ethanol used in step c) is an aqueous solution having an ethanol concentration of 25-100 wt %, and more preferably 95 wt % ethanol aqueous solution. Preferably, in step c) the ethanol added is in an amount of 1-100 liters, and more preferably 10 liters, per kilogram of the Piribedil product. Preferably, the white solid obtained in step f) has a Piribedil purity of 99.8 wt %. detailed-description description="Detailed Description" end="lead"? | 20040329 | 20070710 | 20050929 | 57618.0 | 0 | RAO, DEEPAK R | METHOD FOR THE PURIFICATION OF PIRIBEDIL | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,810,859 | ACCEPTED | Non-hazardous pest control | Pesticidal compositions for the control of pests containing one or more neurally effective substances. In addition, the present invention is directed to a method for controlling pests by applying a pesticidally-effective amount of the pesticidal compositions to a locus where pest control is desired. | 1. A contact pesticide comprising a neurally effective substance dispersed in a carrier, the neurally effect substance comprising benzyl alcohol. | CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of allowed U.S. application Ser. No. 08/657,585, filed Jun. 7, 1996, which is, in turn, a continuation-in-part of Application Serial No. PCT/US94/05823, filed 20 May 1994, now in the U.S. national phase Ser. No. 08/553,475, filed Nov. 9, 1995, which is, in turn, a continuation-in-part of U.S. patent application Ser. No. 08/065,594 filed 21 May 1993 which is now U.S. Pat. No. 5,439,690, issued Aug. 8, 1995. FIELD OF THE INVENTION The present invention relates, in general, to pesticidal compositions containing plant essential oils. In one aspect, the present invention relates to pesticidal compositions containing one or more plant essential oils and/or derivatives thereof to be used as a contact pesticide and/or repellent. In a further aspect, the present invention relates to a method for controlling pests by the application of pesticidally effective amounts of the pesticidal compositions to a locus where pest control is desired. BACKGROUND OF THE INVENTION The present invention relates to the control of pests and, more particularly, to a non-hazardous pest control agent (a.k.a. pesticide) that eliminates pests through either neural effects of a component or mechanical puncture of the exoskeleton and also, through the neurally effective component entering the puncture. Throughout this description, the term “pest” shall include, without limitation, insects and arachnids. Insects and other pests have long plagued humankind. Over the years, various approaches have been taken to control pests and especially insects, and none have been completely satisfactory. For example, the use of complex, organic insecticides, such as disclosed in U.S. Pat. Nos. 4,376,784 and 4,308,279, are expensive to produce, can be hazardous to man, domestic animals, and the environment, and frequently are effective only on certain groups of insects. Moreover, the target insects often build an immunity to the insecticide. Another approach employs absorbent organic polymers for widespread dehydration of the insects. See, U.S. Pat. Nos. 4,985,251; 4,983,390; 4,818,534; and 4,983,389. However, this approach is limited predominantly to aquatic environments, and it likewise relies on hazardous chemical insecticidal agents. Further, the addition of essential oils is primarily as an insect attractant. In addition, this approach is based on the selective absorption of a thin layer of insect wax from the exoskeleton and not to a puncture of the exoskeleton. [Sci. Pharm. Proc. 25th, Melchor et al, pp. 589-597 (1966)]. The use of inorganic salts as components of pesticides is reported by U.S. Pat. Nos. 2,423,284 and 4,948,013, European Patent Application No. 462 347, Chemical Abstracts 119(5):43357q (1993) and Farm Chemicals Handbook, page c102 (1987). These references disclose the inclusion of these components but not the puncturing of the exoskeleton of the insect by the salts. The applicants are also aware of the following which disclose pesticides and insecticides: U.S. Pat. Nos. 4,806,526, 4,834,977, 5,110,594, 5,271,947 and 5,342,630. The marketplace is replete with toxic chemical insecticidal agents that are offensive to apply and, more importantly, pose a danger to humans and the environment. It would be greatly advantageous to solve these problems with a pesticidal agent/composition that works neurally and with a penetrating substance to kill pests, thereby eliminating the need for any chemicals which are toxic to humans and domestic animals. SUMMARY OF THE INVENTION Accordingly, it is an object of the invention to provide a method for non-hazardous pest control and a composition for the same which kills pests neurally and both mechanically and neurally. It is another object to provide a safe, non-toxic pest control agent that will not harm the environment. It is another object to provide a pest control agent that is highly effective in combating a wide variety of pests, including all insects and arachnids having an exoskeleton. It is another object to provide a pest control agent which has either no scent or a pleasant scent, and which can be applied without burdensome safety precautions for humans and domestic animals. It is still another object to provide a pest control agent as described above which can be inexpensively produced. It is yet another object of the invention to provide a pest control agent to which pests cannot build an immunity. In accordance with the above-described and other objects, the present invention provides a pesticide for insects and arachnids comprising a carrier and at least a neurally effective substance. The neurally effective substance has the following Formula wherein R1 is any of the following: CH2, C2H4, C3H6, C3H4, C4H8 or C4H4, R2 is any of the following: H, H2, CH3, C2H5, C3H7, C3H5, C4H9 or R3 is any of the following: H, H2 or OCH3, and wherein the six member ring ABCDEF has at least one unsaturated bond therein. During the course of developing improved insecticidal compositions the inventors have found that various organic compounds when applied in a novel manner will unexpectedly act as a pesticide to kill insects and arachnids. Among the preferred compounds that applicants have found to be insecticidal are terpeniol, phenylethyl alcohol, benzyl acetate, benzyl alcohol, eugenol and cinnamic alcohol. To be affective these compounds should be incorporated into carriers preferably in the form of aerosols, dusts, solutions, liquid emulsions and the like. The herein disclosed invention envisions a pesticide for insects and arachnids comprising a carrier and an effective amount of at least one neurally effective substance. In a specific embodiment the carrier is crystalline dust having a size effective to puncture the exoskeleton and to permit the neurally effective substance to enter the punctured exoskeleton and interfere with the bodily function of the insects and arachnids. Specifically the carrier can be a crystalline powder of a mixture of alkali metal bicarbonate, calcium carbonate, diatomaceous earth and amorphous silica. The crystalline powder has a particle size of 0.1 to 200 microns, and preferably under 100 microns, and the calcium carbonate can be in the form of ground pottery glaze. In an alternative embodiment the carrier is an aerosol spray having a solvent and a propellant, and is compatible and non-reactive with the neurally effective substance. Specifically the solvent can be an organic solvent, either aromatic or aliphatic, and wherein the propellant is carbon dioxide or dimethyl ether. It is to be understood that the solvent is compatible and nonreactive with the neurally effective substances. The neurally effective substances in the composition can be in the range of approximately 0.01% to 10% by weight of the pesticide composition. In some embodiments of the pesticidal composition the neurally effective substance is a mixture of two or more neurally effective substances and/or other diluents included for aesthetic purposes. In an alternative embodiment of the pesticide for controlling insects and arachnids the composition comprises an effective amount of crystalline powder including calcium carbonate, alkali metal bicarbonate, absorbent material and at least one neurally effective substance having a chemical structure represented by the formula wherein R1 is any of the following: CH2, C2H4, C3H6, C3H4, C4H8 or C4H4, R2is any of the following: H, H2, CH3, C2H5, C3H7, C3H5, C4H9 or C4H5, R3 is any of the following: H, H2 or OCH3, and wherein the six member ring ABCDEF has at least one unsaturated bond therein and also an ester of the hydroxyl group on R1 when R1 is CH2, R2is H and R3is H, and specifically an acetate ester. The pesticide formulation contains the neurally effective substance in 0.1% to 10% or more by weight of the pesticide. The crystalline powder of this composition comprises calcium carbonate 27%-35%, sodium bicarbonate 54%-65% and absorbent material 4%-5% by weight. In a particularly elegant embodiment of this invention the pesticide for controlling insects and arachnids comprises an aerosol spray including a solvent, a propellant and an effective amount of at least one neurally effective substance having a chemical structure of wherein R1 is any of the following: CH2, C2H4, C3H6, C3H4, C4H8 or C4H4, R2 is any of the following: H, H2, CH3, C2H5, C3H7, C3H5, C4H9 or C4H5, R3 is any of the following: H, H2 or OCH3, and wherein the six member ring ABCDEF has at least one unsaturated bond therein and wherein the neurally effective substance can be an ester of the hydroxyl group on R1 when R1 is CH2, R2 is H and R3 is H. Specifically the ester is an acetate ester. The neurally effective substance is present in 0.1% to 10% or more by weight of the pesticide. The propellant can be carbon dioxide. The solvent can be an organic solvent. The pesticide for insects and arachnids can contain a solvent and at least one neurally effective substance. In preferred embodiments the compositions are an insecticidal aerosol formulation comprising as the active ingredient a member of the group consisting of terpineol, phenyl ethyl alcohol, benzyl acetate, benzyl alcohol, eugenol, cinnamic alcohol and mixtures thereof contained in an aerosol container including a propellant and a solvent. The above and other objects are accomplished by the present invention, which is directed to pesticidal compositions comprising plant essential oils and/or derivatives thereof, natural or synthetic, in admixture with suitable carriers. In addition, the present invention is directed to a method for controlling pests by applying a pesticidally-effective amount of the above pesticidal compositions to a locus where pest control is desired. Additional objects and attendant advantages of the present invention will be set forth, in part, in the description that follows, or may be learned from practicing or using the present invention. The objects and advantages may be realized and attained by means of the instrumentalities and combinations particularly recited in the appended claims. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not to be viewed as being restrictive of the invention, as claimed. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS All patents, patent applications and literatures cited in this description are incorporated herein by reference in their entirety. Neurally effective/active substances/compounds encompassed within the present invention may comprise the general structural Formula wherein R1 is CH2, C2H4, C3H6, C3H4, C4H8 or C4H4 R2 is H, H2, CH3, C2H5, C3H7, C3H5, C4H9 or C4H5 R3 is H, H2 or OCH3, and The six member ring ABCDEF has at least one unsaturated bond therein. The neurally active substances may also be an ester of the hydroxyl group on R1. Mixtures of several neurally effective substances have been found to be effective. In one embodiment, the present invention provides a pesticidal composition in admixture with a suitable carrier and optionally with a suitable surface active agent, comprising one or more neurally effective substance/compound of the above-described Formula and derivatives thereof, natural or synthetic, including racemic mixtures, enantiomers, diastereomers, hydrates, salts, solvates and metabolites, etc. The neurally effective substance or derivative thereof, may be comprised of a monocyclic, carbocyclic ring structure having six-members and is substituted by at least one oxygenated or hydroxyl functional moiety. Non-limiting examples of neurally effective substances encompassed within the present invention, include members selected from the group consisting of aldehyde C16 (pure), α-terpineol, amyl cinnamic aldehyde, amyl salicylate, anisic aldehyde, benzyl alcohol, benzyl acetate, cinnamaldehyde, cinnamic alcohol, carvacrol, carveol, citral, citronellal, citronellol, p-cymene, diethyl phthalate, dimethyl salicylate, dipropylene glycol, eucalyptol (cineole), eugenol, iso-eugenol, galaxolide, geraniol, guaiacol, ionone, menthol, methyl anthranilate, methyl ionone, methyl salicylate, α-phellandrene, pennyroyal oil, perillaldehyde, 1- or 2-phenyl ethyl alcohol, 1- or 2-phenyl ethyl propionate, piperonal, piperonyl acetate, piperonyl alcohol, D-pulegone, terpinen-4-ol, terpinyl acetate, 4-tert butylcyclohexyl acetate, thyme oil, thymol, metabolites of trans-anethole, vanillin, ethyl vanillin, and the like. The plant essential oils may also include known compounds such as pyrethrins, neem oil, d-limonene, and citronella oil. Particularly preferred examples of neurally effective substances include members selected from the group consisting of: benzyl alcohol, benzyl acetate, phenyl ethyl alcohol, terpineol, cinnamic alcohol, phenol and eugenol. As these compounds are known and used for other purposes, they may be prepared or obtained by a skilled artisan by employing known methods or sources. The effective concentration of the active ingredient will generally be in the range of 0.01% to 10% and will be the primary active ingredient or function as a synergist. It is to be understood that various known active synergists can be added to the disclosed compositions of this invention to enhance the insecticidal activity of the composition. The compositions encompassed by this invention will find application for indoor application as well as outdoor application. The composition can be formulated as a “pet cologne” for application to pets. An odorless composition is contemplated; as well as compositions formulated to avoid allergic reactions. The floral fragrances contemplated by this invention are limitless. None of the individual components are identified by the United States Environmental Protection Agency as having active insecticidal properties. All are considered to be inert in and of themselves at the concentration disclosed herein. Thus, the demonstration of toxic effects on pests is considered to be unexpected. Applicants do not wish to be bound to the theory of neural activity. If the pesticide of the present invention is liberally administered in the vicinity of the insects, it cannot be avoided by the insects and death is imminent. Moreover, it is impossible for the insects to build an immunity to the composition. Most insects have an exoskeleton, cuticle or outer shell which has an outer waxy coating. There are microscopic wax canals in the cuticle. The exoskeleton typically comprises multiple body plates joined together by cartilaginous membrane. This thin shell and the waxy coating is the primary protection the insect has to insure the maintenance of its vital body fluids. If an insect loses as little as 10% of these fluids, it will die. The exoskeleton provides protection against most foreign agents such as pesticidal liquids and powders. For this reason, ingestion is the primary method of delivery for conventional pesticides and may also be a method of delivery of the pesticide of the present invention. However, pests will only ingest certain substances and in small amounts. This imposes limits on the types of usable pesticides and their effectiveness. For instance, insects generally will not ingest fatal amounts of dehydrating pesticide. The present invention proposes new methods of delivery of a pesticide for insects and arachnids. The pesticide is at least one neurally effective chemical having a functional hydroxyl group in the proximity of a six member carbon ring. The neurally effective chemical, it is believed, is capable of dissolving or in some manner, penetrating the cuticle or waxy coated exoskeleton such that the hydroxyl group of the chemical interacts or binds with a vital substance within the insect or arachnid. This binding is fatal to the insect or arachnid. The neurally effective chemical is dispersed in a carrier which may be a dust, aerosol, emulsion or solvent carrier. The aerosol carrier and the liquid carrier provide an effective media to expose the insect or arachnid to the neurally effective chemical. The dust media provides a carrier to mechanically puncture the exoskeleton and accelerate the interaction between the neurally active chemical and the vital substance within the insect or arachnid. The dust media also is a dehydrating agent which provides another mode for killing the insect or arachnid. A dust media containing diatomaceous earth, sodium bicarbonate, calcium carbonate and amorphous silica affect most insects very slowly, usually over several hours. Symptomology of exposure to these dusts is a gradual reduction in activity, slow loss of weight, and eventual death. These dusts do not provide rapid or sudden “knockdown”. Diatomaceous earth is a mild abrasive and desiccant. It abraids the cuticle and adsorbs the outer epicuticlar wax layer of several kinds of insects. Some, but not all, insects that lose the protective wax layer under dry conditions succumb within hours from evaporative loss of body water through the remaining integument. Unaffected insects may have a protective basal cement layer in the cuticle that affords additional protection from desiccation. Because some insects may replace surface wax quickly, a mild desiccant such as diatomaceous earth is not effective when the air is moist and has little evaporative power. Even when effective against insects, diatomaceous earth works fairly slowly. A synergistic effect of calcium carbonate and calcium carbonate with other ingredients is possible, but unlikely. Rapid knockdown or paralysis of insects exposed to heavy deposits of either of these dusts has not been observed. By their physical nature, several kinds of lightweight dusts with small pore size (i.e. very small particle size) that are not ordinarily considered desiccants may adsorb insect wax, in a similar fashion to diatomaceous earth. Adsorption eventually leads to lethal desiccation if the insect cannot replace the lost cuticular wax. The rapid knockdown observed with the dust embodiment of the present pesticide is probably the result of an interaction between one or more of the dusts and a nerve-active substance, rather than from desiccation per se. The neurally effective substance may be the nerve-active substance. Once deposited on an insect, some dusts create a “water continuum” between the inside and outside of the insect. Hemolymph, in the form of lipid-water liquid crystals, is drawn by the dust to the surface from the interior of the insect through microscopic wax canals in the cuticle. Substances carried in the dust may then pass through the continuum into the insect where they come in contact with nerves bathed by the hemolymph. This process may occur very rapidly. Another possibility of action is that the dust components facilitate rapid penetration of an active substance through the cuticle. Oily and alcoholic substances such as the neurally effective substance reported herein may readily penetrate thin or untanned portions of cuticle. The dusts may act as a dust diluent for a more “active” compound. Non-sorptive dusts such as diatomaceous earth tend to be effective diluents because they do not bind substances too tightly, thereby making the substance they carry available to the insect surface. Nerves near spiracles or other sensitive sites may be quickly affected, and may result in rapid knockdown, paralysis or death. Bear in mind that the dust composition of this application, unlike previous dust compositions do not have to be boiled or cooked. The powder (or dust) embodiment is preferably prepared by processing and/or mixing the crystalline solids [alkali metal bicarbonate (54%-65%), calcium carbonate (27%-35%), amorphous silica (1%-3%) and diatomaceous earth (4%-5%)] in a ribbon blender for approximately five to fifteen minutes to obtain a particle size of approximately 1-100 microns and the neurally effective substance (or substances) is then intimately mixed with the blend of crystalline solids. The amorphous silica known as HiSil(R)233 marketed by Harwick, Akron, Ohio has been used satisfactorily. The aerosol embodiment is preferably prepared by mixing the active neurally effective substance or substances (1%-7%) with a solvent such as a mixture of paraffin hydrocarbons (50%-95%). Isoparaffinic hydrocarbons sold by Exxon Corporation known as Isopar H, Isopar L and Isopar M have been used satisfactorily but the solvent is not limited to these products. The mix is introduced into an aerosol container together with a propellant such as carbon dioxide, dimethyl ether, propane or a propane-butane mixture (5%-18%). All proportions are by weight. The liquid formulation or solvent embodiment is preferably prepared by mixing the active neurally effective substance or substances (1%-5%) with the isoparaffin hydrocarbon solvent (75%-99%) and placing the mix into a container which can be used for dispensing the liquid. Use of pesticidal compositions of the present invention generally results in 100% mortality on contact, along with good repellency and residual control. As such, they are advantageously employed as pesticidal agents in uses such as, without limitation, shampoos, hair gels, body cremes, lotions, and other on-skin applications for the treatment of head lice, body lice, and pubic lice. They may also be used in combination with other pesticidally active compounds, to increase efficacy and/or reduce toxicity, generally making conventional pesticides more acceptable. The term “carrier” as used herein means an inert or fluid material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or formulated to facilitate its application to the skin or hair or other object to be treated, or its storage, transport and/or handling. In general, any of the materials customarily employed in formulating pesticides, herbicides, or fungicides, are suitable. The inventive pesticidal compositions of the present invention may be employed alone or in the form of mixtures with such solid and/or liquid dispersible carrier vehicles and/or other known compatible active agents such as other pesticides, or pediculicides, acaricides, nematicides, fungicides, bactericides, rodenticides, herbicides, fertilizers, growth-regulating agents, etc., if desired, or in the form of particular dosage preparations for specific application made therefrom, such as solutions, emulsions, suspensions, powders, pastes, and granules which are thus ready for use. The pesticidal compositions of the present invention can be formulated or mixed with, if desired, conventional inert pesticide diluents or extenders of the type usable in conventional pesticide formulations or compositions, e.g. conventional pesticide dispersible carrier vehicles such as gases, solutions, emulsions, suspensions, emulsifiable concentrates, spray powders, pastes, soluble powders, dusting agents, granules, foams, pastes, tablets, aerosols, natural and synthetic materials impregnated with active compounds, microcapsules, and formulations used with burning equipment, such as fumigating cartridges, fumigating cans and fumigating coils, as well as ULV cold mist and warm mist formulations, etc. Formulations containing the pesticidal compositions of the present invention may be prepared in any known manner, for instance by extending the pesticidal compositions with conventional pesticide dispersible liquid diluent carriers and/or dispersible solid carriers optionally with the use of carrier vehicle assistants, e.g. conventional pesticide surface-active agents, including emulsifying agents and/or dispersing agents, whereby, for example, in the case where water is used as diluent, organic solvents may be added as auxiliary solvents. Suitable liquid diluents or carriers include water, petroleum distillates, or other liquid carriers with or without surface active agents. The choice of dispersing and emulsifying agents and the amount employed is dictated by the nature of the composition and the ability of the agent to facilitate the dispersion of the pesticidal compositions of the present invention. Non-ionic, anionic, amphoteric, or cationic dispersing and emulsifying agents may be employed, for example, the condensation products of alkylene oxides with phenol and organic acids, alkyl aryl sulfonates, complex ether alcohols, quaternary ammonium compounds, and the like. Liquid concentrates may be prepared by dissolving a composition of the present invention with a solvent and dispersing the pesticidal compositions of the present inventions in water with the acid of suitable surface active emulsifying and dispersing agents. Examples of conventional carrier vehicles for this purpose include, but are not limited to, aerosol propellants which are gaseous at normal temperatures and pressures, such as Freon; inert dispersible liquid diluent carriers, including inert organic solvents, such as aromatic hydrocarbons (e.g. benzene, toluene, xylene, alkyl naphthalenes, etc.), halogenated especially chlorinated, aromatic hydrocarbons (e.g. chloro-benzenes, etc.), cycloalkanes, (e.g. cyclohexane, etc.). paraffins (e.g. petroleum or mineral oil fractions), chlorinated aliphatic hydrocarbons (e.g. methylene chloride, chloroethylenes, etc.), alcohols (e.g. methanol, ethanol, propanol, butanol, glycol, etc.) as well as ethers and esters thereof (e.g. glycol monomethyl ether, etc.), amines (e.g. ethanolamine, etc.), amides (e.g. dimethyl formamide etc.) sulfoxides (e.g. dimethyl sulfoxide, etc.), acetonitrile, ketones (e.g. acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), and/or water; as well as inert dispersible finely divided solid carriers such as ground natural minerals (e.g. kaolins, clays, vermiculite, alumina, silica, chalk, i.e. calcium carbonate, talc, attapulgite, montmorillonite, kieselguhr, etc.) and ground synthetic minerals (e.g. highly dispersed silicic acid, silicates, e.g. alkali silicates, etc.). Surface-active agents, i.e., conventional carrier vehicle assistants, that may be employed with the present invention include, without limitation, emulsifying agents, such as non-ionic and/or anionic emulsifying agents (e.g. polyethylene oxide esters of fatty acids, polyethylene oxide ethers of fatty alcohols, alkyl sulfates, alkyl sulfonates, aryl sulfonates, albumin hydrolyzates, etc. and especially alkyl arylpolyglycol ethers, magnesium stearate, sodium oleate, etc.); and/or dispersing agents such as lignin, sulfite waste liquors, methyl cellulose, etc. In the preparation of wettable powders, dust or granulated formulations, the active ingredient is dispersed in and on an appropriately divided carrier. In the formulation of the wettable powders the aforementioned dispersing agents as well as lignosulfonates can be included. Dusts are admixtures of the compositions with finely divided solids such as talc, attapulgite clay, kieselguhr, pyrophyllite, chalk, diatomaceous earth, vermiculite, calcium phosphates, calcium and magnesium carbonates, sulfur, flours, and other organic and inorganic solids which acts carriers for the pesticide. These finely divided solids preferably have an average particle size of less than about 50 microns. A typical dust formulation useful for controlling pests contains 1 part of pesticidal composition and 99 parts of diatomaceous earth or vermiculite. Granules may comprise porous or nonporous particles. The granule particles are relatively large, a diameter of about 400-2500 microns typically. The particles are either impregnated or coated with the inventive pesticidal compositions from solution. Granules generally contain 0.05-15%, preferably 0.5-5%, active ingredient as the pesticidally-effective amount. Thus, the contemplated are formulations with solid carriers or diluents such as bentonite, fullers earth, ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth vermiculite, and ground synthetic minerals, such as highly-dispersed silicic acid, alumina and silicates, crushed and fractionated natural rocks such as calcite, marble, pumice, sepiolite and dolomite, as well as synthetic granules of inorganic and organic meals, and granules of organic materials such as sawdust, coconut shells, corn cobs and tobacco stalks. Adhesives, such as carboxymethyl cellulose, natural and synthetic polymers, (such as gum arabic, polyvinyl alcohol and polyvinyl acetate), and the like, may also be used in the formulations in the form of powders, granules or emulsifiable concentrations. If desired, colorants such as inorganic pigments, for example, iron oxide, titanium oxide and Prussian Blue, and organic dyestuffs, such as alizarin dyestuffs, azo dyestuffs or metal phthalocyanine dyestuffs, and trace elements, such as salts of iron, manganese, boron, copper, cobalt, molybdenum and zinc may be used. In commercial applications, the present invention encompasses carrier composition mixtures in which the pesticidal compositions are present in an amount substantially between about 0.01-95% by weight, and preferably 0.5-90% by weight, of the mixture, whereas carrier composition mixtures suitable for direct application or field application generally contemplate those in which the active compound is present in an amount substantially between about 0.0001-10%, preferably 0.01-1%, by weight of the mixture. Thus, the present invention contemplates over-all formulations that comprise mixtures of a conventional dispersible carrier vehicle such as (1) a dispersible inert finely divided carrier solid, and/or (2) a dispersible carrier liquid such as an inert organic solvent and/or water, preferably including a surface-active effective amount of a carrier vehicle assistant, e.g. a surface-active agent, such as an emulsifying agent and/or a dispersing agent, and an amount of the active compound which is effective for the purpose in question and which is generally between about 0.0001-95%, and preferably 0.01-95%, by weight of the mixture. Furthermore, the present invention encompasses methods for killing, combating or controlling pests, which comprises applying to at least one of correspondingly (a) such pests and (b) the corresponding habitat thereof, i.e. the locus to be protected, e.g. to the head or body, a correspondingly combative, a pesticidally effective amount, or toxic amount of the particular pesticidal compositions of the invention alone or together with a carrier as noted above. The instant formulations or compositions may be applied in any suitable usual manner, for instance by shampooing, rubbing, spreading, spraying, atomizing, vaporizing, scattering, dusting, watering, squirting, sprinkling, pouring, fumigating, and the like. The method for controlling human body louse comprises applying the inventive composition, ordinarily in a formulation of one of the aforementioned types, to a locus or area to be protected from the human body louse, such as the hair or scalp. The compound, of course, is applied in an amount sufficient to effect the desired action. This dosage is dependent upon many factors, including the targeted pest, the carrier employed, the method and conditions of the application, whether the formulation is present at the locus in the form of a shampoo, hair gel, creme, or body lotion, an aerosol, or as a film, or as discrete particles, the thickness of film or size of particles, and the like. Proper consideration and resolution of these factors to provide the necessary dosage of the active compound at the locus to be protected are within the skill of those versed in the art. In general, however, the effective dosage of the compound of this invention at the locus to be protected-i.e., the dosage with which the pest comes in contact-is of the order of 0.001 to 5.0% based on the total weight of the formulation, though under some circumstances the effective concentration will be as little as 0.0001% or as much as 20%, on the same basis. The pesticidal compositions and methods of the present invention are effective against different species of human body louse, including head lice, body lice and pubic lice, and it will be understood that the body lice exemplified and evaluated in the working Examples herein is representative of such a wider variety. The composition and method of the present invention will be further illustrated in the following, non-limiting Examples. The Examples are illustrative of various embodiments only and do not limit the claimed invention regarding the materials, conditions, weight ratios, process parameters and the like recited herein. EXAMPLE 1 The following aerosol formulations of the present invention may be prepared. The active ingredient included in the formulations herein comprise a neurally effective substance, a combination of neurally effective substances, or a combination of neurally effective substances and other diluents added for aesthetic purposes. It has been found that synergistic effects are produced with various combinations. 1. 3% active ingredient 20% DME (Dimethyl ether) 1.5% Propanol 75.5% Isopar M 2. 1.5% active ingredient 20.0% DME (Dimethyl ether) 1.5% Propanol 77.0% Isopar M 3. 3.0% active ingredient 3.5% CO2 (Carbon dioxide) 1.5% Propanol 92.0% Isopar M 4. 1.5% active ingredient 3.5% CO2 (Carbon dioxide) 1.5% Propanol 93.5% Isopar M 5. Active ingredient: 1-7% by weight Solvent A: 50-94.1% by weight (any of the following) (a) Isopar H (b) Isopar L (c) Isopar M Solvent B: 0-10% by weight (any of the following) (a) d Limonene (b) Synthetic Solvents EE-195 (c) Synthetic Solvents EE-216 (d) Synthetic Solvents EE-235 Propellant: 4.9%-18% by weight (a) Carbon dioxide (b) Propane (c) Propane-butane mixture The solvents and propellants may be any of the listed materials and/or combinations thereof and are not limited to those identified above. The materials identified have been found to be satisfactory. CO2 (carbon dioxide) and DME (dimethyl ether) are the preferred propellants used in the aerosol formulations, however other propellants known to those skilled in the art would be operative. Propanol is used to make the active ingredient miscible with the Isopar M. Isopar M is not considered by EPA or the state of California as a VOC (volatile organic compound). EXAMPLE 2 A typical liquid formulation is as follows: Active insecticide: 1-5% by weight Solvent A: 75-99% by weight (a) Isopar H (b) Isopar L (c) Isopar M Solvent B: 0-20% by weight (a) d Limonene (b) Synthetic Solvents EE-195 (c) Synthetic Solvents EE-216 (d) Synthetic Solvents EE-235 Solvent C: 75-99% by weight (a) Soltrol 100 It is to be understood that the percentages set forth herein are approximations and can be varied within degrees by those skilled in the art and still attain effective results. Also, other substances may be used. The above-identified materials have been used satisfactorily. Soltrol 100 is a solvent of isoparaffinic hydrocarbons (C9 through C11) sold by Philips Chemical Co. The solvents listed may be used individually or in any combination. A fragrance may be added if desired to enhance the marketing of the pesticide, especially for indoor use and for general retail markets. The pesticide may be used domestically, commercially, indoors, outdoors, for pets, nurseries, and agriculturally. The pesticide of the present invention has also been found to be useful for control of head lice on humans and as a repellent to be used on the skin of humans. The resulting aerosol or liquid solvent formulations of the invention are compositions capable of directly invading the exoskeleton of most insects and arachnids. There are over one million species of common pests such as ants, roaches, fleas, termites, beetles, mites and spiders. All are potential targets. Emulsifiable concentrate formulations are within the preview of this invention. These emulsifiable concentrates are particularly useful for outdoor application to plant foliage. These emulsifiable concentrates are easy to use; simply mix with water in the proper proportions and spray with conventional spray applicators. Emulsifiers and surfactants well known in the art can be used in preparing the emulsions which can penetrate plant material to aid in producing systemic action. EXAMPLE 3 A study was conducted to determine the insecticidal activity of the present invention against commonly found insects such as German cockroaches, cat fleas and Argentine ants. As described the term “dust” is used for the insecticide in a dry crystalline powder form and the term “powder” is used for dry formulations that are intended to be mixed with water. Tests With Cockroaches Continuous exposure tests.—The intrinsic insecticidal activity of the insecticide dust against B. germanica was determined by exposing cockroaches to fresh and aged deposits of the dust. Replicated groups of three to ten adult cockroaches from culture were confined to deposits of the dust, and its speed of action in terms of knockdown (KD) and paralysis was determined. Adult male cockroaches from culture were placed directly onto fairly heavy deposits of dust (1 to 1.2 cc) spread evenly on filter paper in covered 9-cm-diameter petri dishes. The time for irreversible KD to occur (KT) was determined from periodic, irregular observation. The insects were considered KD when they were on their back, or could be turned over, and could not right themselves within at least two minutes. KT-50 and KT-90 values (time for 50% and 90% KD, respectively) were calculated by interpolation of KD between times when data was collected; average KT value were obtained from the individual KD data. Comparison of KD activity was made with some commercial dust formulations including a non-fluorinated silica aerogel (SG-68), Drione™ (a fluorinated silica aerogel+pyrethrins), and a commercial diatomaceous earth (Celite™) applied and tested in the same manner. The effects of atmospheric moisture and deposit age on the efficacy of the present insecticide dust were determined by the speed of action (KT) on cockroaches confined to deposits of the dust aged and tested at 98% (high) and 58% (moderate) relative humidity (RH). Average KT values were determined for fresh dust and for dust aged 2 weeks and 4 weeks. Cockroaches were exposed to 1 cc of dust in petri dishes, as described previously. Eighteen-mesh window screen covers on the dishes allowed for maintenance of the proper humidity and kept cockroaches from escaping from the damp dusts. For these tests dishes of dust were aged and tested on a wire mesh platform in saran-sealed aquaria. Enough dishes were prepared so that each deposit was tested only once. Water below the platform was used to maintain 98% RH, and a saturated aqueous sodium bromide solution was used to maintain 58% RH. Choice box tests.—The activity and repellency of the present insecticide dust in a choice test was determined with standard two-compartment choice boxes. Choice boxes are 30.5 cm square, 10 cm tall wooden boxes, with a tempered masonite floor. A vertical partition panel separates the box into two equal-sized compartments. A 1.3 cm hole at the top center of the partition panel allows cockroaches to move from one compartment to the other. Transparent sheet plexiglass (0.3 cm thick) taped to the top retains cockroaches in the box and allows observation of live and dead in each compartment. A piece of masonite keeps one compartment dark (dark compartment). The other compartment (light compartment) is exposed to normal room light conditions. Five boxes were used for each treatment and the untreated control. For these tests 10 cc of test dust was spread evenly over the floor of the dark compartment and 20 adult male B. germanica were released into the light compartment, where there was food and water. A cork in the partition hole was removed two hours later, when the cockroaches settled. Cockroaches prefer to aggregate in the dark, and they will normally readily move from the light compartment to the dark compartment of untreated choice boxes within a day or two. Once the partition cork was removed, the insects could move from the light compartment into treated dark compartment. The number dead and alive in each compartment of each box was recorded every few days. It was presumed that mortality was produced by contact with the insecticide in the dark, regardless of where the insects eventually died. Reluctance to move into the dark is attributable to the repellency of the treatment. Repellent treatments usually result in increased survivorship in the light compartment. The mortality produced in choice boxes, and the position of cockroaches in relation to the treatment, provides a measure of the likely ultimate efficacy of a treatment when used under actual field conditions. In choice box tests, cockroaches are given an opportunity to encounter or avoid insecticide deposits. Highly toxic deposits may be ineffectual if cockroaches sense their presence and avoid lethal contact with them. On the other hand, slow-acting insecticides such as boric acid are effective in choice box tests because cockroaches readily walk on those deposits and are eventually killed by them. Tests with Cat Fleas Adult cat fleas, cultured under laboratory conditions were used in the study. Eggs collected from caged cats were reared through the larval period to adulthood on a special blood media. Adults used in the tests were approximately 2 to 3 days old (i.e., 2 to 3 days post-eclosion from the cocoon stage). Speed of action of minimal deposits.—The rate of knockdown of fleas exposed to filter paper treated with the present insecticide dust and SG-68 silica aerogel was determined. Strips of No. 1 Whatman filter paper measuring 2 cm by 15 cm were submerged in the dusts and the excess shaken off. The lightly dusted strips were slipped into 2.5 cm- diameter by 15 cm tall glass test tubes and groups of fleas were directed from rearing emergence jars into the tubes. The open end of the tube was covered with parafilm. The tubes were left in a vertical position in a test tube rack. Because such a small amount of dust was used, all of it adhered to the paper and none could be seen on the surface of the test tubes. The fleas contacted the dust when they walked on the paper. Exposure to the dust was ensured because live fleas prefer the paper surface to the smooth surface of the test tube. Knockdown of fleas in the tubes was observed and recorded every few minutes until all the fleas were down. The fleas were considered KD if they were paralyzed at the bottom of the tube. Rate of KD (KT) was interpolated from the number of fleas KD at each time of observation. Exposures on dusted carpet.—The minimum lethal dose and potential effectiveness of the present insecticide dust against fleas indoors was determined by exposing aliquots of fleas to a series of decreasing dosages of the dust on carpet. Dri-Die™ SG-68, a sorptive desiccant silica aerogel, was used as a comparative standard. Weighed amounts of dust were sifted as evenly as possible onto the surface of 9-cm-diameter disks of new shag carpet at the bottom of 9 cm by 45-cm-tall plastic cylinders. The carpet was made of 100% nylon fibers and a jute backing. It has 9 double-stranded loops per cm2, each strand being about 1.6 cm long. The highest rate of dust applied was 1.2 cc/disk [14.2 cc/929cm2; that rate was successively halved and tested to the lowest rate of 0.06 cc/929cm2 (i.e., 9 rates tested)]. For exposure on each treatment rate, fleas from eclosion jars were directed onto the carpet, where they were confined for 24 hours. One or two replicates of 12 to 20 fleas were used for most rates, but 3 replicates were used for some rates. Because fleas cannot climb on the plastic or jump high enough to escape, they remained in contact with the carpet at the bottom of the cylinder. Untreated disks served as controls. Tests were conducted under ambient laboratory conditions (approximately 74° F. and 45% RH) and in an incubator cabinet at 98% RH. The efficacy of the dust treatments was determined from the percentage of fleas that died within a 24-hour exposure period. Live and dead fleas on each disk were counted after tapping all the fleas from a disk into a basin of cool water. Live fleas move and swim vigorously. Fleas were considered dead if they sank, were immobile, or if they only had feeble, barely perceptible movement of their appendages. Effect of humidity and volatility.—The specific application rate of 1.8 cc/929cm2 was used to compare the activity and volatility of the “active ingredient” in the present insecticide dust and some other dusts at ambient and 98% RH. Using the method described above, mortality at 24 hours was determined for fleas exposed to fresh insecticide, insecticide baked 48 hours at 250° F., diatomaceous earth, and silica aerogel. It was presumed that high temperature might drive off volatile actives, and that abrasive diatomaceous earth or sorptive non-fluorinated silica gel would provide greater kill at low humidity than at high humidity. Differences between rates of kill may indicate the mode of action of the insecticide dust. Tests with Argentine Ants Based on the results obtained with the present insecticide in tests against cockroaches and fleas, Argentine ants were exposed to selected low doses of the dust as well as to comparative doses of SG-68 desiccant. Worker ants collected from a citrus grove were aspirated for study approximately 30 minutes before the test began. Aliquots of ants (11-15 for each of three replicates per treatment) were dumped onto lightweight deposits of the present insecticide dust and SG-68 spread evenly over the surface of filter paper waxed into the floor of 9-cm diameter glass petri dishes. Knockdown of the ants was observed every 5 minutes until all the ants in the treatments were down. An untreated set of papers served as a control series. The exposure tests provided an indication of the relative speed of action of the present insecticide and the SG-68 dusts against this species. Results And Discussion An embodiment of the present invention mixes an alkaline earth metal carbonate, such as calcium carbonate, an alkali metal bicarbonate, such as sodium bicarbonate, at least one neurally effective substance, and an absorbent material, such as diatomaceous earth. In addition, inert ingredients such as silica gel and a scenting agent may be added as desired in varying amounts for color and texture. Aside from the scenting agent, all of the above-mentioned ingredients are preferably mixed in powdered form. The relative concentrations of the mixture are preferably about 30%-35% alkaline earth carbonate, 60%-65% alkali metal carbonate, 1%-2% neurally effective substance, and 4$-5% absorbent material (all by weight). However, the individual constituents may vary within the following ranges while still achieving the desired result: 5%-91% alkaline earth carbonate, 6%-95% alkali metal carbonate, 1%-93% neurally effective, and up to 90% absorbent material (all by weight). The mix is ground to a powder, preferably having a granular size of less than 100 microns. The irreversible knockdown (KD) of cockroaches exposed to fresh and aged deposits of this embodiment the present insecticide at moderate and high humidities is summarized in Table 1. TABLE 1 Knockdown of adult male German cockroaches confined to dust deposits aged and tested at high (98%) and moderate (58%) humidity. Treat- Avg. hours for KD on deposits of indicated age menta Fresh 2 Weeks 4 Weeks RH KT-50 KT-90 KT-50 KT-90 KT-50 KD-90 Present 58% 0.3 0.6 0.3 0.7 0.3 0.7 insec- ticide Silica 6.1 16.0 4.3 5.8 7.4 18.4 gel Celite (39%)b (6%) (42%) Un- (0%) (0%) (16%) treated Present 98% 0.3 0.5 0.6 1.2 0.7 1.3 insec- ticide Silica 6.7 12.3 8.3 17.3 13.3 21.9 gel Celite (4%) (0%) (16%) Un- (0%) (0%) (13%) treated a1 cc/9-cm-diam petri dish. Five replicates each with 10 cockroaches, were used for each exposure. Dusts spread onto Whatman No. 1 filter paper. Silica gel was SG-68 silica aerogel, an aerogel containing no fluoride. Celite is a commercial diatomaceous earth filter aid (Manville, Hyflo ™). bNumbers in parentheses indicate total % KD at 24 hours, in instances where average KT-50 was not achieved. The present insecticide dust provided rapid KD of German cockroaches, the average KT-50 being about 18 minutes, and 100% being down within about 40 minutes. Neither high humidity nor aging up to 4 weeks had a deleterious effect on its speed of action against cockroaches. Because even the most rapid-action desiccants require >30 minutes for KD, the effect observed with present insecticide suggests that the toxic action of the dust was not attributable solely to a sorptive ingredient. The affected cockroaches had curled or distended abdomens, and looked to be paralyzed as when toxified by a nervous system insecticide. As expected, the non-fluorinated SG-68 desiccant took several hours to kill cockroaches, and was slightly less effective at high humidity. Typically, the desiccated cockroaches died standing upright, and did not show signs of tremors or paralysis. Diatomaceous earth (like Celite™) alone is not usually considered to be an effective insecticide. Being an abrasive, the toxic action of diatomaceous earth occurs as a result of dusted insects slowly losing body water through abraded cuticle. Because moist air has little evaporative power, Celite™ was even less effective at high humidity. Choice box tests with cockroaches.—Although the present insecticide dust provided rapid kill in continuous exposure tests, there was significant survivorship in the choice tests. There is usually a direct relationship between the speed of action of an insecticide and its repellency, and this relationship appears to have been confirmed in the choice box study. As shown in Table 5, deposits of the present insecticide dust provided mediocre kill of cockroaches in choice boxes, with 52% of the cockroaches being alive at 7 days and 40% alive at 14 days. Boric acid dust, on the other hand, provided 98% kill of cockroaches within a week. Table 2 also shows that a high percentage of the live cockroaches in choice boxes treated with the present insecticide were always in the less-preferred light compartment, away from the dust. This was not so with boric acid, a non-repellent insecticide. Avoidance of the dust by survivors is characteristic of repellent insecticides such as silica gels (repellent by nature of their small particle size and sorptive properties) and fast-knockdown toxicants such as pyrethrins and pyrethroids. TABLE 2 Activity and repellency of fresh dust deposits against German cockroaches, as measured in choice boxes. % Mortality % of live in on day light on day Days for KDb Dusta 1 7 14 1 7 14 KT-50 KT-90 Present 25 48 60 84 100 100 7.7 — insecticide Boric acid, 0 98 100 13 100 — 4.0 5.7 tech. Untreated 0 3 10 12 3 18 — — a10 cc dust spread evenly over floor of dark compartment. For each dust, 3 replicates were tested, each with 20 adult male B. germanica. bKT-50 and KT-90 are average days for 50% and 90% of the cockroaches to be irreversibly knocked down (KD). The present insecticide dust, therefore, had high intrinsic insecticidal action against cockroaches, it had excellent activity at high and low humidity, and it retained activity for at least a month. The dust was, however, somewhat repellent, resulting in a high percentage of cockroaches surviving in choice tests. Direct application to cockroaches would certainly kill them. Speed of action and minimum effective dose against fleas. A low dose of the present insecticide dust provided very rapid knockdown of adult fleas. On paper in tubes it took nearly 4 hours for 90% knockdown of fleas on SG-68 silica gel, but less than 5 minutes for knockdown on the present insecticide. As with cockroaches, this rapid action suggests the presence of a nerve-involving insecticide rather than an adsorptive desiccant or an abrasive. The good activity against fleas at a low dose was substantiated in the series of exposure tests with successively lower doses of the present insecticide on carpet. As shown in Table 3, complete kill of fleas was achieved with as little as 0.2 cc/929 cm2 of the present invention. Lower doses were not effective. TABLE 3 Minimum effective dosages of fresh dust deposits on carpet against adult cat fleas, Cunocephalides felis. % Mortality of fleas at 24 hoursa Silica gel Rate Present insecticide (SG-68) (cc/929 cm2)b Ambient RH 98% RH Ambient RH 98% RH 14.2 100 100 100 100 7.1 100 100 100 100 3.6 100 100 100 100 1.8 100 93.6 100 92.3 0.9 100 100 100 100 0.4 100 77.8 100 42.9 0.2 100 81.8 100 46.7 0.1 23.5 — 100 — 0.06 4.1 — 1.8 — Untreated 9.7 11.3 — — a% mortality of treatments corrected with Abbott's formula to account for control mortality. bRates extrapolated from volume amounts applied to 78.5 cm2 carpet discs. Highest rate applied (14.2 cc/929 cm2) is equivalent to 1.2 cc/disc; other rates are proportional. High humidity appeared to reduce the effectiveness of the dust at low rates of application as shown in Table 4. TABLE 4 Effect of humidity on the activity of a low dose of dust deposit against adult cat fleas. % Mortality at indicated RHa Dust treatment Ambient 98% Present insecticide 100 93.6 Present insecticide 72.7 2.8 (baked)b Celite 21.4 23.1 Silica gel 100 92.3 Untreated 5.6 6.4 aFresh powders (1.8 cc/929 cm2) applied to carpet. Fifteen to 20 fleas confined to treatments 24 hours. One to 2 replicates per treatment. Ambient humidity 25-40% RH. bHeated 48 hours in hot-air oven at 250° F. Surprisingly, the SG-68 also provided good kill at approximately the same low rates. Since SG-68 is a non-toxic desiccant, it could have been concluded erroneously that the present insecticide dust also killed fleas by desiccating them. The much more rapid action found in the test tube assay suggests that there is a toxic component in the present insecticide formulation. The toxic component appears to involve toxification of the insect's nerves or cells. Activity of the present insecticide against Argentine ants.—The rapid activity of the present insecticide against Argentine ants is shown in Table 5. TABLE 5 Activity of minimal dust deposits against the Argentine ant, Iridomyrmex humilis. Rate Time for (cc/929 % Dead at minutes of exposure KD (min) Dust cm2) 5 10 20 40 60 80 KT-50 KT-90 Present 0.2 36 100 6.0 9.2 Insect- <0.06 23 32 100 11.2 14.2 icide SG-68 0.2 0 0 0 23 66 89 55.9 75.7 <0.06 0 0 0 24 84 100 49.5 60.3 Un- — 0 0 0 0 7 7 — — treat- ed aMortality based on 3 replicates, each with 11-15 worker ants. The lightweight deposit (0.2 cc/929 cm2) knocked down all the ants in less than 10 minutes; and an extremely light deposit (<0.06 cc/929 cm2) provided effects that were nearly as rapid. The latter deposit was achieved by brushing a small amount of the dust onto the paper, and then tapping the remnant dust off the paper as the dish was inverted. Only a very small amount of dust remained. The SG-68 desiccant had a somewhat slower effect, resulting in high levels of KD within about 50 to 75 minutes. Desiccants such as SG-68 are active against ants such as these, perhaps because this ant has a relatively low percentage body water (<70%) and a large surface area compared to its body volume, a combination of which allows for rapid water loss from this insect. As with the exposures of cockroaches and fleas, the ants contacting the present insecticide dust exhibited classic symptoms of neural toxication. Ants contacting the dust were quickly paralyzed. There was rapid running and apparent irritation before the onset of paralysis, a symptom often observed with ants exposed to finely divided dusts and fast-acting insecticides. There appeared to be less irritation among ants exposed to SG-68. As with all dust formulations, care should be exercised to minimize airborne particulates of the dust at the time of application or afterwards. This may be more important if the dust is applied to carpet or furnishings for controlling fleas than if applied along baseboards, under appliances, or in other similar places for controlling cockroaches or ants. The presence of a volatile active component in the present insecticide formulation was preliminarily verified when the activity of fresh insecticide was compared to that of heated (i.e., baked) insecticide. As shown in Table 4, the present insecticide baked 48 hours at 250° F. was less effective against fleas, and was significantly less effective when tested at high humidity. Baking apparently removed volatile active components or altered the configuration of the dust diluent. That removal or alteration reduced activity. Baking at higher temperature may reduce performance even more. Pyrethins and other botanical insecticides volatilize at 250° F., but can reportedly be more quickly and thoroughly removed at 350° F. The effectiveness compares favorably to conventional pesticides, yet the above-described product is primarily inorganic and completely non-hazardous to humans and other animals. An improved embodiment of the present invention using the neurally effective substances with the inorganic dust was prepared and tested as described below. A control test was conducted using only the solid components of the embodiment. As summarized in Table 6, the least active dust substance was calcium carbonate, (CaCO3). Only 10% of the cockroaches exposed to deposits of CaCO3 were KD within 24 hours. The activity of CaCO3 was not statistically different from the untreated control, and was the most inert of the ingredients tested. Amorphous silica (HiSil(R)233 marketed by Harwick, Akron, Ohio has been used satisfactorily), on the other hand, is a potent desiccant and was the most active of the dry ingredients, it's average KT90 being 6.7 hours. The addition of amorphous silica to CaCO3 proportionately increased the activity of the CaCO3 obviously because of the sorptive qualities of the amorphous silica. As expected, diatomaceous earth and sodium bicarbonate were not highly insecticidal but they did provide significant KD within 24 hours. These data suggested that calcium carbonate was a suitable inert ingredient with which to determine the relative effects attributable to the neurally effective substances. CaCO3 was used as an inert carrier or diluent in further tests to determine mechanisms of insecticidal action as described hereinafter. TABLE 6 Average hours (± standard deviation) for 50% and 90% knockdown of adult male German cockroaches, Blattella, germanica, continuously confined to dust deposits. KT50 KT90 Dust or dust mix Hours SD Hours SD Calcium carbonate (CaCO3) — — (10% KD at 24 h) Amorphous silica (AS) 4.9 0.38 6.7 1.38 Diatomaceous Earth (DE) 11.8 1.44 16.8 3.03 Sodium bicarbonate (NaHCO3) 16.5 0.48 20.9 0.10 CaCO3 + 30% AS 6.5 1.00 9.3 1.53 CaCO3 + 30% AS + 5% DE 6.3 1.19 10.8 3.70 CaCO3 + 36% NaHCO3 19.5 0.50 (80% KD at 24 h) CaCO3 + 5% AS 13.7 3.44 19.4 1.52 Untreated control — — (0% KD at 24 h) Average values based on 3 replicates, each with 10 cockroaches. SD = standard deviation. Exposures at 76° F., 55% relative humidity. The pesticidal activity of the neurally effective substances combined only with CaCO3 was determined. Each respective neurally effective substance was formulated at 5% (wt/wt) in CaCO3 and cockroaches were confined to the mixture as described above for exposures to the dry dust ingredients. Weighed quantities of compound were added to CaCO3 and the mix was thoroughly stirred in 500 ml glass beakers and then shaken with glass boiling beads in a capped specimen jar. The beads were screened out of the resultant mix. Exactly 1.2 cc of dust or dust was spread onto Whatman filter paper in 9-cm-diam petri dishes and the knockdown (KD) of cockroaches confined to the dust mix was determined by periodically observing KD. The insecticidal activity of the neurally effective substances is summarized in Table 7. Again, CaCO3 was not insecticidal and both sodium bicarbonate and diatomaceous earth provided comparatively slow KD. The most active neurally effective substances were benzyl acetate, phenyl ethyl alcohol, and terpineol. Each of these substances provided 90% KD of cockroaches in about one hour or so. Amyl cinnamic aldehyde was much slower, about as active as diatomaceous earth. Diethyl phthalate and dipropylene glycol may impart some favorable odor characteristics but they were not insecticidal. The complete dust embodiment of the present invention as described herein provided fastest KD, the KT90 for it being only about 0.5 hours. TABLE 7 Average hours (± standard deviation) for 50% and 90% knockdown of German cockroaches continuously confined to calcium carbon- ate + 5% ingredients of neurally effective substance. KT50 KT90 Dust or dust mix Hours ±SD Hours ±SD Calcium carbonate (dust) — — (1.3% KD at 24 h) Sodium bicarbonate (dust) 9.7 0.48 16.0 1.88 Diatomaceous Earth (dust) 9.4 0.00 15.5 0.00 Amyl cinnamic aldehyde, 5% 9.4 0.00 15.5 0.00 Benzyl acetate 0.7 0.05 1.0 0.18 Diethyl phthalate — — (0% KD at 18 h) Phenyl ethyl alcohol 0.7 0.09 1.0 0.25 Dipropylene glycol — — (23% KD at 18 h) Terpineol 0.7 0.08 1.1 0.17 Dust embodiment* 0.2 0.06 0.5 0.03 Average values based on 3 replicates, each with 10 cockroaches. SD = standard deviation. Exposures in laboratory at 78 ± 4° F., 55 ± 6% rh. *The dust embodiment of the present invention contains benzyl acetate, terpineol and phenyl ethyl alcohol. The above exposure trials with cockroaches indicate that the rapid pesticidal action of the formulation of the present invention is due to the neurally effective substance, not to any of the powdered components, either individually or combined. A further test was conducted to compare the effectiveness of phenol vs. terpineol as a neurally effective substance. The respective substances were mixed with calcium carbonate at a range of wt/wt mixes. The preparations were tested using German cockroaches with the results provided in Table 8. TABLE 8 Average hours for 50% and 90% knockdown of German cockroaches continuously confined to calcium carbon- ate + ingredients of phenol and terpineol Dust % (wt/wt) KT-50 (h) KT-90 (h) Phenol 5.0 <0.1 0.1 2.5 0.2 0.4 1.25 0.4 1.5 0.63 7.5 20.3 0.32 16.5 24.0 Terpineol 5.0 0.6 0.9 2.5 9.4 20.6 1.25 11.4 23.5 0.63 14.7 22.1 Phenol was more insecticidal than terpineol. It is also much more toxic to humans and other mammals than are the other neurally effective substances tested. Cockroaches killed in the phenol mix turned black. At every rate tested, phenol provided faster KD. The minimum active dose for fresh phenol in CaCO3 was approximately between 1.25% and 0.63%. The minimum active dose for fresh terpineol was above 2.5%. This assay confirms the theory as discussed below that speed of insecticidal activity of the neurally effective substances may be associated with the complexity and isomeric configuration of hydroxyl attachments to a six member carbon ring. Having now fully set forth a detailed example and certain modifications incorporating the concept underlying the present invention, various other modifications will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically set forth herein. The mode of action of the neurally effective substances disclosed herein is not known. Each of the substances is considered to be non-toxic by the U.S. Food and Drug Administration and are frequently used in food and food additives. The applicants are unaware of pesticidal activity reported or ascribed to the neurally effective compounds as specifically taught herein. It is proposed that in biology, the body's receptacles have an affinity for hydroxyl compounds, and are absorbed into the nerve endings, creating a genomic effect, which is highly desirable in a mode of action context. The more distal from the six member carbon ring that the hydroxyl is, the less likely it is that the body can metabolize this compound to the point that the hydroxyl can attach itself to the receptacle. Separation of the hydroxyl group from the ring by a chain of up to four (4) carbon atoms results in a corresponding decrease in activity. In general, carbon chains of five (5) or greater are usually inactive. There is credible evidence that this in fact takes place, based on theories that estrogen and other pharmeuticals work in this manner. It is further postulated that the esters such as benzyl acetate are active because the body hydrolyzes the ester, enabling the hydroxyl group to become available for interaction with the body's receptacles. However, applicants do not wish to be bound by any specific theory of operation. EXAMPLE 4 An unscented aerosol pesticide composition (Eco PCO ACU (ADL-2-12-A) , EcoSmart Technologies, Inc.) comprising neurally active benzyl alcohol was made. The unscented composition contained: 10% Arylessence AA029661 (which contains Benzyl Alcohol (88.04%), Tetrahydrofurfuryl Alcohol (10.87%) and Phenethyl Propionate 1.09%) 4% Isopropyl Alcohol 71.9% Isopar M, and 14% Propellant A-108. The compositions were evaluated as to their effectiveness in the control of the following target pests: Southern fire ant, Argentine ant, Carpenter ant, Cat flea, European earwig, Brown dog tick, Carpet beetle, House fly, Field cricket, American cockroach, German cockroach, Paper wasp, Western subterranean termite, Southern house mosquito, Pillbug, Long-bodied cellar spider, and Wolf spider. A scented aerosol composition (Eco PCO AC (ADL-2-12-B), EcoSmart Technologies, Inc.) was also tested as a positive control. Sprays of the compositions were all directed at the target pest and the surrounding substrate, and mortality was assessed at varying time periods. The testing protocols and results are set forth below in Examples 5. EXAMPLE 5 Southern Fire Ant, Solenopsis xyloni Life Stage: Adult workers Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Southern fire ants were field collected in Fresno County, Calif. The ants were held for about 2 hours prior to study initiation. The ants were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the ants moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead ants was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The ants became agitated immediately upon being sprayed with the test products. At 1 minute posttreatment 87.5% of the ants were dead in the treatment of Eco PCO ACU (ADL-2-l 2-A), compared to 67.5% in the treatment with Eco PCO AC (ADL-2-12-B) (Table 2). All sprayed ants were dead within 5 minutes, and complete survival was observed in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - Southern fire ant. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.0 0.5 1.2 0.7 0.9 (ADL-2-12-A) Eco PCO AC 0.6 0.5 0.3 0.9 0.6 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead southern fire ants (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 7 (70.0) 8 (80.0) 10 (100.0) 10 (100.0) 8 (87.5) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 8 (80.0) 7 (70.0) 6 (60.0) 6 (60.0) 6 (67.5) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 6 Argentine Ant, Iridomyrmex humilis Life Stage: Adult workers Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Argentine ants were field collected in Fresno County, Calif. The ants were held for about 2 hours prior to study initiation. The ants were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the ants moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead ants was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The ants became agitated immediately upon being sprayed with the test products. At 1 minute posttreatment 100% of the ants were dead in the Eco PCO ACU (ADL-2-12-A) and Eco PCO AC (ADL-2-12-B) treatments (Table 2). Complete survival was observed in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application-Argentine ant. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.8 1.6 1.1 1.1 1.2 (ADL-2-12-A) Eco PCO AC 0.9 1.2 0.8 0.5 0.9 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead Argentine ants (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 7 Carpenter Ant, Camponotus modoc Life Stage: Adult workers Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Carpenter ants were field collected in Fresno County, Calif. The ants were held for about 24 hours prior to study initiation. The ants were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. Wood chips collected at the site were placed in the bottoms of the cups and the ants moved freely over the surface. Honey was provided as a food source. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and wood surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead ants was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The carpenter ants initially became agitated after the spray application and then slowed down in movement. Mortality was relatively slow compared to the other insects tested. The test product, Eco PCO ACU (ADL-2- 12-A) caused total kill within 24 hours after application, but Eco PCO AC (ADL-2-12-B) gave a high of 90% control at the final, 48 hour observation (Table 2). Complete survival was observed in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application-Carpenter ant. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.8 0.8 1.0 0.7 0.8 (ADL-2-12-A) Eco PCO AC 1.1 0.5 0.9 0.5 0.8 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead Carpenter ants (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 1 (10.0) 2 (20.0) 0 (0.0) 0 (0.0) 1 (7.5) (ADL-2-12-A) 5 min. 3 (30.0) 7 (70.0) 5 (50.0) 6 (60.0) 5 (52.5) 10 min. 3 (30.0) 7 (70.0) 6 (60.0) 8 (80.0) 6 (60.0) 1 hr. 6 (60.0) 8 (80.0) 8 (80.0) 10 (100.0) 8 (80.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 2 (20.0) 1 (10.0) 0 (0.0) 1 (10.0) 1 (10.0) (ADL-2-12-B) 5 min. 4 (40.0) 4 (40.0) 0 (0.0) 1 (10.0) 2 (22.5) 10 min. 4 (40.0) 9 (90.0) 5 (50.0) 2 (20.0) 5 (50.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 6 (60.0) 9 (90.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 6 (60.0) 9 (90.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 6 (60.0) 9 (90.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 8 Cat flea, Ctenocephalides felis Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Adult cat fleas were obtained from EL-Labs of Soquel, Calif. The fleas were held for about 3 hours prior to study initiation. Ten fleas were contained in each shipping vial along with a few wood shavings. A quick jar to the uncapped vials transferred the fleas into clear plastic cups (14 cm high×11 cm dia). The fleas were held at 70° F. during the test. The cup lids were secured until after the spray application. A circular disc of olefin fiber carpet (Bretlin Company, Calhoun, Ga.) was placed in the bottom of each cup and a clay border secured the edges of the carpet. The fleas moved freely over the carpet surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and carpet surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead fleas was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: All cat fleas were dead within 5 minutes after the spray application. Test product Eco PCO ACU caused 97.5% kill within 1 minute posttreatment and Eco PCO AC caused 87.5% mortality. No mortality occurred in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - cat flea. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.9 0.8 0.8 0.5 0.8 (ADL-2-12-A) Eco PCO AC 0.6 0.6 0.5 0.5 0.6 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead cat fleas (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 9 (90.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (97.5) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 8 (80.0) 7 (70.0) 9 (87.5) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 9 European Earwig, Forficula auricularia Life Stage: Adult - 6 per replicate Nymph - 4 per replicate Experimental Design: Randomized Complete Block Design Replication: 3 # Organisms per Replicate: 10 Holding Conditions: Adults and nymphs of European earwigs were field collected in Fresno County, Calif. The earwigs were held for about 2 hours prior to study initiation. The earwigs were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the earwigs moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of earwigs was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The earwigs became agitated immediately upon being sprayed with the test products. At 1 minute posttreatment all earwigs were dead in the Eco PCO ACU (ADL-2-12-A) and Eco PCO AC (ADL-2-12-B) treatments. No recovery occurred. TABLE 1 Amount of product (grams) dispensed at each spray application - European earwig. Replicate Treatment 1 2 3 Mean Eco PCO ACU 1.5 1.5 1.6 1.5 (ADL-2-12-A) Eco PCO AC 0.7 1.2 1.2 1.0 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 TABLE 2 Number of dead earwigs (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Post- treat- ment Replicate Treatment Time 1 2 3 Mean Eco PCO 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) ACU (ADL-2- 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 12-A) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) AC (ADL-2- 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 12-B) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Un- 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) treated 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 10 Brown Dog Tick, Rhipicephalus sanguineus Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Adult brown dog ticks were obtained from EL-Labs of Soquel, Calif. The ticks were held for about 3 hours prior to study initiation and were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of olefin fiber carpet (Bretlin Company, Calhoun, Ga.) was placed in the bottom of the cups, and the ticks moved freely over the carpet surface. A clay border around the carpet prevented the ticks from escaping along the edges. Ticks which moved onto the sides of the containers were gently brushed back onto the carpet surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test ticks. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the ticks and carpet surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead ticks was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: Both test products, Eco PCO ACU (ADL-2-12-A) and Eco PCO AC (ADL-2-12-B) caused complete kill of the adult ticks within 1 hour after the spray applications. Treatment with Eco PCO APU resulted in the best kill with 20.0%, 42.5%, and 80.0% mortality at 1, 5, and 10 minutes posttreatment whereas Eco PCO AC caused 5.0%, 37.5%, and 55% kill at the same time periods. No mortality occurred in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - brown dog tick. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.0 1.3 1.1 0.9 1.1 (ADL-2-12-A) Eco PCO AC 1.0 0.6 0.9 1.6 1.0 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead brown dog ticks (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 2 (20.0) 3 (30.0) 1 (10.0) 2 (20.0) 2 (20.0) (ADL-2-12-A) 5 min. 4 (40.0) 5 (50.0) 3 (30.0) 5 (50.0) 4 (42.5) 10 min. 9 (90.0) 9 (90.0) 6 (60.0) 8 (80.0) 8 (80.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 2 (20.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (5.0) (ADL-2-12-B) 5 min. 7 (70.0) 2 (20.0) 4 (40.0) 2 (20.0) 4 (37.5) 10 min. 8 (80.0) 4 (40.0) 5 (50.0) 5 (50.0) 6 (55.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 11 Carpet Beetle, Attagenus flavipes Life Stage: Mature larvae Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Carpet beetle larvae were obtained from a colony maintained at the University fo California, Riverside. The larvae were held for one day prior to study initiation. Ten larvae were transferred onto circular discs of olefin fiber carper (Bretlin Company, Calhoun, Ga.). The carpet was held inside petri dishes (100 mm×15 mm). A small amount of feathers was placed on the carpet to serve as a food source. The larvae were held at 70° F. during the test. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and carpet surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead larvae was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. The larvae were examined under a dissecting microscope during the holdiong period. Death was defined as the inability of the organism to move when probed. Results and Discussion: All carpet beetle larvae were dead within I minute after the spray application. Test product Eco PCO ACU and Eco PCO AC both caused total mortality. No mortality occurred in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - Carpet beetle larvae. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.5 0.5 0.7 0.5 0.6 (ADL-2-12-A) Eco PCO AC 0.7 0.5 0.5 0.4 0.5 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead carpet beetle larvae (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 12 House Fly, Musca domestica Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: House flies were obtained as puparium from Rincon-Vitova Insectaries, Inc. of Ventura, Calif. After emergence as adults they were transferred into plastic cylinders (22.0 cm high×9.0 cm diameter) with a screen at one end and a spray portal at the opposite end, and held at 70° F. The cup lids were removed during the test. Flies moved freely inside the cage. No food or water was provided. Spray Application: A “soda straw” (provided with the canisters) was attached to the canister nozzle. A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was then directed at the test insects by spraying through the portal. No spray was applied to the untreated control. Complete spray coverage of the insects and the interior surface of the cylinder was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead flies was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: House flies were knocked down immediately upon being sprayed with the test products. At 1 minute posttreatment all (100.0%) of the flies were dead in the treatment of Eco PCO ACU (ADL-2-12-A), compared to 97.5% in the treatment with Eco PCO AC (ADL-2-12-B) (Table 2). All sprayed flies were dead within 5 minutes in the ECO PCO AC (ADL-2-12-B) treatment. Complete survival was observed in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - House fly. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.6 0.5 0.7 0.5 0.6 (ADL-2-12-A) Eco PCO AC 1.0 0.6 0.7 0.5 0.7 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead house flies (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 9 (90.0) 10 (97.5) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 13 Field Cricket, Acheta assimilis Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Field crickets were obtained from a local insectary. The crickets were held for about 3 hours prior to study initiation. The crickets were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the crickets moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead crickets was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: All crickets were dead within 1 minute after the spray application of EcoPCO ACU (ADL-2-12-A) (Table 2). An average of 87.5% death occurred in the positive control pesticidal composition within the same time frame, and total death occurred within 5 minutes. No death occurred in the untreated group during the holding period. TABLE 1 Amount of product (grams) dispensed at each spray application - field cricket. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 0.5 0.5 0.8 0.8 0.7 (ADL-2-12-A) Eco PCO AC 0.4 0.4 0.5 0.5 0.5 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead crickets (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 7 (70.0) 10 (100.0) 8 (80.0) 10 (100.0) 9 (87.5) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 14 American Cockroach, Periplaneta americana Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 5 Holding Conditions: American cockroaches were obtained from a colony maintained at S. C. Johnson & Sons, Racine, Wis. The cockroaches were held for about 2 days prior to study initiation. The cockroaches were then transferred into clear plastic cups (7.5 cm high×11 cm diameter) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup and Fluon (polytetrafluoroethylene) was painted on the inside of the cups. Fluon is a dry lubricant and prevented the cockroaches from crawling up the sides of the cup. The cockroaches moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead cockroaches was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The cockroaches became agitated immediately upon being sprayed with the test products. At 1 minute posttreatment 30.0% of the cockroaches were dead in the treatment of Eco PCO ACU (ADL-2-12-A), compared to 10.0% in the treatment with Eco PCO AC (ADL-2-12-B) (Table 2). All sprayed cockroaches were dead within 5 minutes in the Eco PCO ACU (ADL-2- 12-A) treatment, whereas it took 10 minutes for total kill in the Eco PCO AC (ADL-2-12-B) treatment. No mortality occurred in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - American cockroach. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.3 1.1 0.7 1.1 1.0 (ADL-2-12-A) Eco PCO AC 0.8 0.8 0.6 0.8 0.8 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead American cockroaches (% mortality) n = 5 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 1 (20.0) 1 (20.0) 1 (20.0) 3 (60.0) 1 (30.0) (ADL-2-12-A) 5 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 10 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 1 hr. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 24 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 48 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) Eco PCO AC 1 min. 0 (0.0) 1 (20.0) 0 (0.0) 1 (20.0) 1 (10.0) (ADL-2-12-B) 5 min. 5 (100.0) 5 (100.0) 4 (80.0) 5 (100.0) 4 (95.0) 10 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 1 hr. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 24 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 48 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 15 German Cockroach, Blatella germanica Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: German cockroaches were field collected from infested apartments in Fresno, California. The cockroaches were held for about 4 days prior to study initiation. The cockroaches were then transferred into clear plastic cups (7.5 cm high×11 cm diameter) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup and Fluon (polytetrafluoroethylene) was painted on the inside of the cups. Fluon is a dry lubricant and prevented the cockroaches from crawling up the sides of the cup. The cockroaches moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test insects. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the insects and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead cockroaches was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The cockroaches became agitated immediately upon being sprayed with the test products. At 1 minute posttreatment total (100%) of the cockroaches were dead in the treatment of Eco PCO ACU (ADL-2-12-A), compared to 95% in the treatment with Eco PCO AC (ADL-2-12-B) (Table 2). All sprayed cockroaches were dead in both treatments within 5 minutes. Only slight mortality occurred in the untreated group. TABLE 1 Amount of product (grams) dispensed at each spray application - German cockroach. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.0 0.5 0.6 0.8 0.7 (ADL-2-12-A) Eco PCO AC 0.8 0.9 0.5 0.5 0.7 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead German cockroaches (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 9 (90.0) 10 (100.0) 9 (90.0) 10 (100.0) 9 (95.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 1 (10.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) 24 hrs. 1 (10.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (2.5) 48 hrs. 1 (10.0) 0 (0.0) 1(10.0) 0 (0.0) 2 (5.0) EXAMPLE 16 Paper Wasp, Polistes prob. fuscatus Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 5 Holding Conditions: Paper wasps were field collected in Fresno County, California and held for 1 day prior to test initiation. The wasps were transferred into plastic cylinders (22.0 cm high×9.0 cm diameter) with a screen at one end and a spray portal at the opposite end, and held at 70° F. The wasps moved freely inside the cage. Honey was provided as food. Spray Application: A “soda straw” (provided with the canisters) was attached to the canister nozzles. A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was then directed at the test insects by spraying through the portal. No spray was applied to the untreated control. Complete spray coverage of the insects and the interior surface of the cylinder was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead wasps was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: The paper wasps were knocked down immediately upon being sprayed with the test products. At 10 minutes posttreatment all (100.0%) of the wasps were dead in the treatment of Eco PCO ACU (ADL-2-12-A), and at 5 minutes all (100%) of the wasps were dead in the Eco PCO AC (ADL-2-12-B) treatment (Table 2). TABLE 1 Amount of product (grams) dispensed at each spray application - Paper wasp. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.0 0.6 0.8 1.2 0.9 (ADL-2-12-A) Eco PCO AC 1.0 1.0 1.0 1.2 1.1 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead paper wasps (% mortality) n = 5 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 4 (80.0) 1 (20.0) 2 (40.0) 1 (20.0) 2 (40.0) (ADL-2-12-A) 5 min. 5 (100.0) 3 (60.0) 4 (80.0) 3 (60.0) 4 (75.0) 10 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 1 hr. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 24 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 48 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) Eco PCO AC 1 min. 2 (40.0) 2 (40.0) 2 (40.0) 4 (80.0) 3 (50.0) (ADL-2-12-B) 5 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 10 min. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 1 hr. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 24 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 48 hrs. 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) 5 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 1 (20.0) 1 (5.0) EXAMPLE 17 Western Subterranean Termite, Reticulitermes hesperus Life Stage: Adult workers Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Termites were field collected in Fresno County, Calif. They were held for about 1 hour prior to study initiation. The termites were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the termites moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test organisms. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the termites and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead termites was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: One minute after treatment all (100%) of the termites sprayed with Eco PCO ACU (ADL-2-12-A) and Eco PCO AC (ADL-2-12-B) were dead. No mortality occurred in the untreated group during the first 6 hours of the test. It then increased to 100% death by 48 hours. This was likely due to the low humidity in the test cages and/or lack of food. This late mortality, however, likely had no affect on the results of the experiment. TABLE 1 Amount of product (grams) dispensed at each spray application - Termite. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.0 1.1 1.3 0.9 1.1 (ADL-2-12-A) Eco PCO AC 1.1 0.7 0.6 0.8 0.8 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead termites (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) (ADL-2-12-B) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 9 (90.0) 9 (90.0) 9 (90.0) 9 (90.0) 9 (90.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) EXAMPLE 18 Southern House Mosquito, Culex pipiens quinquefasciatus Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: Variable Test Conditions: Mosquito eggs were obtained from the Mosquito Control Research Laboratory, Parlier, Calif. and were reared at Bio Research until the pupal stage. As adult emergence occurred the pupae were transferred into plastic cups. The mosquitoes that emerged in each cup represented one replicate group. Only one group of mosquitoes were treated at a time. Prior to each spray application the aerosol canisters were tested to insure proper function. The pre-treatment canister weight was recorded. A cup containing a high number of emerged adults was selected and brought into the test chamber (5′×5′×8′ walk-in closet), which was maintained at 65 to 75° F., and the door was closed. The lid was removed from the cup allowing the mosquitoes to fly freely within the chamber. After a five-minute acclimation period, any mosquito that appeared unhealthy or unable to fly was removed from the trial. The test materials were then applied. A three second burst was sprayed upwards in all directions. The number of mosquitoes knocked down was recorded at 1, 3, 5, 10, 15, 30 and 60 minutes after treatment. The researcher remained in the closed chamber for the first 15 minutes, then returned for the 30 and 60 minute evaluations. A cloth sheet hung over the doorway prevented the mosquitoes from escaping when the door was opened. The aerosol canister was weighed again, so the amount of material could be quantified (Table 1). The chamber was then thoroughly cleaned with a 2% bleach solution. A large fan was placed in the open chamber and ran for at least one hour. When the odor of bleach could no longer be detected the chamber was considered ready for the next treatment. The untreated group was tested randomly during the study to assess any effects of unremoved residues. Evaluation: The number of dead mosquitoes was assessed at 1, 3, 5, 10, 15, 30 and 60 minutes posttreatment. Death was defined as the inability of the organism to move. Results and Discussion: The test product Eco PCO ACU (ADL-2-12-A) caused 59.2% death within 1 minute after application, but total kill required 60 minutes. The Eco PCO AC (ADL-2-12-B) treatment caused 31.5% death within 1 minute but only caused 84.2% kill by 60 minutes (Table 2). TABLE 1 Amount of product (grams) dispensed at each spray application - Mosquito. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 9.5 9.8 7.9 8.9 9.0 (ADL-2-12-A) Eco PCO AC 10.3 5.7 6.4 7.7 7.5 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead mosquitoes per total and % mortality at 1, 3, 5, 10, 15, 30, and 60 minutes posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 15/23 30/39 8/23 21/40 59.2 (ADL-2-12-A) 3 min. 19/23 30/39 11/23 24/40 67.2 5 min. 21/23 34/39 12/23 25/40 73.6 10 min. 22/23 36/39 16/23 26/40 80.0 15 min. 23/23 36/39 18/23 29/40 84.8 30 min. 23/23 38/39 21/23 34/40 92.8 60 min. 23/23 39/39 23/23 40/40 100.0 Eco PCO AC 1 min. 12/24 7/27 5/41 22/54 31.5 (ADL-2-12-B) 3 min. 14/24 10/27 7/41 35/54 45.2 5 min. 15/24 12/27 8/41 38/54 50.0 10 min. 19/24 16/27 9/41 41/54 58.2 15 min. 19/24 18/27 10/41 41/54 60.3 30 min. 23/24 23/27 15/41 43/54 71.2 60 min. 23/24 24/27 28/41 48/54 84.2 Untreated 1 min. 0/29 0/47 0/42 0/56 0.0 3 min. 0/29 0/47 0/42 0/56 0.0 5 min. 0/29 0/47 0/42 0/56 0.0 10 min. 0/29 0/47 0/42 0/56 0.0 15 min. 0/29 0/47 0/42 0/56 0.0 30 min. 1/29 1/47 0/42 0/56 0.0 60 min. 2/29 2/47 0/42 0/56 0.0 EXAMPLE 19 Pillbug, Armadillidium vulgare Life Stage: Adult Experimental Design: Randomized Complete Block Design Replication: 4 # Organisms per Replicate: 10 Holding Conditions: Pillbugs were field collected in Fresno County, Calif. They were held for about 2 hours prior to study initiation. The pillbugs were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. The cup lids were removed during the test. A circular disc of vinyl flooring was placed in the bottom of each cup, and the pillbugs moved freely over the floor surface. No food or water was provided. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test organisms. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the pillbugs and floor surface was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead pillbugs was assessed at 1, 5, and 10 minutes and at 1, 24, and 48 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: One minute after treatment 40% of the pillbugs sprayed with EcoPCO ACU (ADL-2-12-A) were dead, compared to 35% of those sprayed with EcoPCO AC (ADL-2-12-B). Five minutes after treatment all pillbugs sprayed with EcoPCO ACU (ADL-2-12-A) were dead, whereas 82.5% of those sprayed with EcoPCO AC (ADL-2-12-B) were moribund. Ten minutes after treatment all sprayed pillbugs were dead. No mortality occurred in the untreated group during the holding period (Table 2). TABLE 1 Amount of product (grams) dispensed at each spray application - Pillbug. Replicate Treatment 1 2 3 4 Mean Eco PCO ACU 1.3 0.9 0.7 1.2 1.0 (ADL-2-12-A) Eco PCO AC 1.1 0.5 0.8 1.0 0.9 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead pillbugs (% mortality) n = 10 at 1, 5, and 10 minutes and 1, 24, and 48 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 Mean Eco PCO ACU 1 min. 1 (10.0) 4 (40.0) 5 (50.0) 6 (60.0) 4 (40.0) (ADL-2-12-A) 5 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Eco PCO AC 1 min. 3 (30.0) 4 (40.0) 3 (30.0) 4 (40.0) 4 (35.0) (ADL-2-12-B) 5 min. 9 (90.0) 8 (80.0) 7 (70.0) 9 (90.0) 8 (82.5) 10 min. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 1 hr. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 24 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 48 hrs. 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) 10 (100.0) Untreated 1 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 10 min. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 hr. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 24 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 48 hrs. 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) EXAMPLE 20 Long-Bodied Cellar Spider (Pholcus phalagiodes) Life Stage: Adult Experimental Design: Randomized Replication: 10 # Organisms per Replicate: 1 Test Conditions: A site was located in Fresno County, Calif. where cellar spiders were common. The researcher sprayed each spider with the test product and then observed mortality. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test organisms. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the spider and webbing was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead spiders was assessed at 1, 5, and 10 minutes and at 1 hour posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: One minute after treatment 70% of the cellar spiders sprayed with Eco PCO ACU (ADL-2-12-A) were dead, compared to none (0%) of those sprayed with Eco PCO AC (ADL-2-12-B). Five minutes after treatment all spiders sprayed with Eco PCO ACU (ADL-2-12-A) were dead, whereas 60% of those sprayed with Eco PCO AC (ADL-2-12-B) were moribund. One hour after the spray application all spiders were dead in the Eco PCO AC treatment. No mortality occurred in the untreated group during the test period (Table 2). TABLE 1 Amount of product (grams) dispensed at each spray application - Cellar spider. Replicate Treatment 1 2 3 4 5 6 7 8 9 10 Mean Eco PCO ACU 0.8 1.2 0.7 0.5 1.1 0.5 0.7 0.7 1.0 1.1 0.8 (ADL-2-12-A) Eco PCO AC 0.8 0.5 1.0 0.8 0.9 1.1 0.7 0.6 0.9 0.6 0.8 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead cellar spiders (% mortality) n = 1 at 1, 5, and 10 minutes and 1 hour posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 5 6 7 8 9 10 Mean Eco PCO ACU 1 min. * * * * * * * 7 (70.0) (ADL-2-12-A) 5 min. * * * * * * * * * * 10 (100.0) 10 min. * * * * * * * * * * 10 (100.0) 1 hour * * * * * * * * * * 10 (100.0) Eco PCO AC 1 min. 0 (0.0) (ADL-2-12-B) 5 min. * * * * * * 6 (60.0) 10 min. * * * * * * * * 8 (80.0) 1 hour * * * * * * * * * * 10 (100.0) Untreated 1 min. 0 (0.0) 5 min. 0 (0.0) 10 min. 0 (0.0) 1 hour 0 (0.0) * spider dead EXAMPLE 21 Wolf Spider (family: Lycosidae), Lycosa sp. Life Stage: Adult Experimental Design: Randomized Replication: 10 # Organisms per Replicate: 1 Test Conditions: Wolf spiders were field collected from the lawn at the Bio Research facility. They were held for 2 hours prior to study initiation. The spiders were then transferred into clear plastic cups (7.5 cm high×11 cm dia) and held at 70° F. One spider was placed into each cup. The sides of the cups were treated with Fluon and a circular disc of vinyl flooring was placed in the bottom of each cup. The spiders moved freely over the floor surface. No food or water was provided. The researcher sprayed each spider with the test product and then observed mortality. Spray Application: A short burst of the unscented pesticidal composition, or the positive control pesticidal composition was directed at the test organisms. No spray was applied to the untreated control. The spray canister was held 30 cm from the target. Complete spray coverage of the spider and flooring was observed. The amount of product dispensed was determined by weighing the canister before and after each spray (Table 1). Evaluation: The number of dead spiders was assessed at 1, 5, and 10 minutes and at 1 and 24 hours posttreatment. Death was defined as the inability of the organism to move when probed. Results and Discussion: One minute after treatment 50% of the wolf spiders sprayed with Eco PCO ACU (ADL-2- 12-A) were dead, compared to 90% of those sprayed with Eco PCO AC (ADL-2-12-B). Five minutes after treatment all spiders sprayed with Eco PCO ACU or Eco PCO AC were dead. No mortality occurred in the untreated group during the test period (Table 2). TABLE 1 Amount of product (grams) dispensed at each spray application - Wolf spider. Replicate Treatment 1 2 3 4 5 6 7 8 9 10 Mean Eco PCO ACU 0.9 0.7 0.4 0.8 1.0 0.9 0.9 1.4 0.9 0.9 0.9 (ADL-2-12-A) Eco PCO AC 1.1 1.2 1.1 0.6 1.0 0.6 1.0 0.5 0.7 0.6 0.8 (ADL-2-12-B) Untreated 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TABLE 2 Number of dead wolf spiders (% mortality) n = 1 at 1, 5, and 10 minutes and 1 and 24 hours posttreatment. Posttreatment Replicate Treatment Time 1 2 3 4 5 6 7 8 9 10 Mean Eco PCO ACU 1 min. * * * * * 5 (50.0) (ADL-2-12-A) 5 min. * * * * * * * * * * 10 (100.0) 10 min. * * * * * * * * * * 10 (100.0) 1 hour * * * * * * * * * * 10 (100.0) 24 hour * * * * * * * * * * 10 (100.0) Eco PCO AC 1 min. * * * * * * * * * 9 (90.0) (ADL-2-12-B) 5 min. * * * * * * * * * * 10 (100.0) 10 min. * * * * * * * * * * 10 (100.0) 1 hour * * * * * * * * * * 10 (100.0) 24 hour * * * * * * * * * * 10 (100.0) Untreated 1 min. 0 (0.0) 5 min. 0 (0.0) 10 min. 0 (0.0) 1 hour 0 (0.0) 24 hour 0 (0.0) * spider dead As can be seen from the above discussion, the pesticidal combinations of active compounds according to the present invention are markedly superior to known pesticidal agents/active compounds conventionally used for control of pests. Although illustrative embodiments of the invention have been described in detail, it is to be understood that the present invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the invention as defined by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to the control of pests and, more particularly, to a non-hazardous pest control agent (a.k.a. pesticide) that eliminates pests through either neural effects of a component or mechanical puncture of the exoskeleton and also, through the neurally effective component entering the puncture. Throughout this description, the term “pest” shall include, without limitation, insects and arachnids. Insects and other pests have long plagued humankind. Over the years, various approaches have been taken to control pests and especially insects, and none have been completely satisfactory. For example, the use of complex, organic insecticides, such as disclosed in U.S. Pat. Nos. 4,376,784 and 4,308,279, are expensive to produce, can be hazardous to man, domestic animals, and the environment, and frequently are effective only on certain groups of insects. Moreover, the target insects often build an immunity to the insecticide. Another approach employs absorbent organic polymers for widespread dehydration of the insects. See, U.S. Pat. Nos. 4,985,251; 4,983,390; 4,818,534; and 4,983,389. However, this approach is limited predominantly to aquatic environments, and it likewise relies on hazardous chemical insecticidal agents. Further, the addition of essential oils is primarily as an insect attractant. In addition, this approach is based on the selective absorption of a thin layer of insect wax from the exoskeleton and not to a puncture of the exoskeleton. [Sci. Pharm. Proc. 25th, Melchor et al, pp. 589-597 (1966)]. The use of inorganic salts as components of pesticides is reported by U.S. Pat. Nos. 2,423,284 and 4,948,013, European Patent Application No. 462 347, Chemical Abstracts 119(5):43357q (1993) and Farm Chemicals Handbook, page c102 (1987). These references disclose the inclusion of these components but not the puncturing of the exoskeleton of the insect by the salts. The applicants are also aware of the following which disclose pesticides and insecticides: U.S. Pat. Nos. 4,806,526, 4,834,977, 5,110,594, 5,271,947 and 5,342,630. The marketplace is replete with toxic chemical insecticidal agents that are offensive to apply and, more importantly, pose a danger to humans and the environment. It would be greatly advantageous to solve these problems with a pesticidal agent/composition that works neurally and with a penetrating substance to kill pests, thereby eliminating the need for any chemicals which are toxic to humans and domestic animals. | <SOH> SUMMARY OF THE INVENTION <EOH>Accordingly, it is an object of the invention to provide a method for non-hazardous pest control and a composition for the same which kills pests neurally and both mechanically and neurally. It is another object to provide a safe, non-toxic pest control agent that will not harm the environment. It is another object to provide a pest control agent that is highly effective in combating a wide variety of pests, including all insects and arachnids having an exoskeleton. It is another object to provide a pest control agent which has either no scent or a pleasant scent, and which can be applied without burdensome safety precautions for humans and domestic animals. It is still another object to provide a pest control agent as described above which can be inexpensively produced. It is yet another object of the invention to provide a pest control agent to which pests cannot build an immunity. In accordance with the above-described and other objects, the present invention provides a pesticide for insects and arachnids comprising a carrier and at least a neurally effective substance. The neurally effective substance has the following Formula wherein R 1 is any of the following: CH 2 , C 2 H 4 , C 3 H 6 , C 3 H 4 , C 4 H 8 or C 4 H 4 , R 2 is any of the following: H, H 2 , CH 3 , C 2 H 5 , C 3 H 7 , C 3 H 5 , C 4 H 9 or R 3 is any of the following: H, H 2 or OCH 3 , and wherein the six member ring ABCDEF has at least one unsaturated bond therein. During the course of developing improved insecticidal compositions the inventors have found that various organic compounds when applied in a novel manner will unexpectedly act as a pesticide to kill insects and arachnids. Among the preferred compounds that applicants have found to be insecticidal are terpeniol, phenylethyl alcohol, benzyl acetate, benzyl alcohol, eugenol and cinnamic alcohol. To be affective these compounds should be incorporated into carriers preferably in the form of aerosols, dusts, solutions, liquid emulsions and the like. The herein disclosed invention envisions a pesticide for insects and arachnids comprising a carrier and an effective amount of at least one neurally effective substance. In a specific embodiment the carrier is crystalline dust having a size effective to puncture the exoskeleton and to permit the neurally effective substance to enter the punctured exoskeleton and interfere with the bodily function of the insects and arachnids. Specifically the carrier can be a crystalline powder of a mixture of alkali metal bicarbonate, calcium carbonate, diatomaceous earth and amorphous silica. The crystalline powder has a particle size of 0.1 to 200 microns, and preferably under 100 microns, and the calcium carbonate can be in the form of ground pottery glaze. In an alternative embodiment the carrier is an aerosol spray having a solvent and a propellant, and is compatible and non-reactive with the neurally effective substance. Specifically the solvent can be an organic solvent, either aromatic or aliphatic, and wherein the propellant is carbon dioxide or dimethyl ether. It is to be understood that the solvent is compatible and nonreactive with the neurally effective substances. The neurally effective substances in the composition can be in the range of approximately 0.01% to 10% by weight of the pesticide composition. In some embodiments of the pesticidal composition the neurally effective substance is a mixture of two or more neurally effective substances and/or other diluents included for aesthetic purposes. In an alternative embodiment of the pesticide for controlling insects and arachnids the composition comprises an effective amount of crystalline powder including calcium carbonate, alkali metal bicarbonate, absorbent material and at least one neurally effective substance having a chemical structure represented by the formula wherein R 1 is any of the following: CH 2 , C 2 H 4 , C 3 H 6 , C 3 H 4 , C 4 H 8 or C 4 H 4 , R 2 is any of the following: H, H 2 , CH 3 , C 2 H 5 , C 3 H 7 , C 3 H 5 , C 4 H 9 or C 4 H 5 , R 3 is any of the following: H, H 2 or OCH 3 , and wherein the six member ring ABCDEF has at least one unsaturated bond therein and also an ester of the hydroxyl group on R 1 when R 1 is CH 2 , R 2 is H and R 3 is H, and specifically an acetate ester. The pesticide formulation contains the neurally effective substance in 0.1% to 10% or more by weight of the pesticide. The crystalline powder of this composition comprises calcium carbonate 27%-35%, sodium bicarbonate 54%-65% and absorbent material 4%-5% by weight. In a particularly elegant embodiment of this invention the pesticide for controlling insects and arachnids comprises an aerosol spray including a solvent, a propellant and an effective amount of at least one neurally effective substance having a chemical structure of wherein R 1 is any of the following: CH 2 , C 2 H 4 , C 3 H 6 , C 3 H 4 , C 4 H 8 or C 4 H 4 , R 2 is any of the following: H, H 2 , CH 3 , C 2 H 5 , C 3 H 7 , C 3 H 5 , C 4 H 9 or C 4 H 5 , R 3 is any of the following: H, H 2 or OCH 3 , and wherein the six member ring ABCDEF has at least one unsaturated bond therein and wherein the neurally effective substance can be an ester of the hydroxyl group on R 1 when R 1 is CH 2 , R 2 is H and R 3 is H. Specifically the ester is an acetate ester. The neurally effective substance is present in 0.1% to 10% or more by weight of the pesticide. The propellant can be carbon dioxide. The solvent can be an organic solvent. The pesticide for insects and arachnids can contain a solvent and at least one neurally effective substance. In preferred embodiments the compositions are an insecticidal aerosol formulation comprising as the active ingredient a member of the group consisting of terpineol, phenyl ethyl alcohol, benzyl acetate, benzyl alcohol, eugenol, cinnamic alcohol and mixtures thereof contained in an aerosol container including a propellant and a solvent. The above and other objects are accomplished by the present invention, which is directed to pesticidal compositions comprising plant essential oils and/or derivatives thereof, natural or synthetic, in admixture with suitable carriers. In addition, the present invention is directed to a method for controlling pests by applying a pesticidally-effective amount of the above pesticidal compositions to a locus where pest control is desired. Additional objects and attendant advantages of the present invention will be set forth, in part, in the description that follows, or may be learned from practicing or using the present invention. The objects and advantages may be realized and attained by means of the instrumentalities and combinations particularly recited in the appended claims. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not to be viewed as being restrictive of the invention, as claimed. detailed-description description="Detailed Description" end="lead"? | 20040329 | 20060919 | 20050106 | 62552.0 | 0 | PAK, JOHN D | NON-HAZARDOUS PEST CONTROL | SMALL | 1 | CONT-ACCEPTED | 2,004 |
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10,810,997 | ACCEPTED | Modular automatic spray gun manifold | A modular automatic spray gun manifold is provided. The manifold includes a plurality of spray gun modules arranged in an array in laterally spaced relation from each other. A junction element is arranged at an upstream end of the manifold. The junction element includes a liquid supply connection and a pressurized air connection. A first support assembly is arranged between the junction element and a first spray gun module in the spray gun module array for supporting the first spray gun module relative to the junction element. The first support assembly includes a plurality of fluid conduits for supplying fluid to the first spray gun module. The fluid conduits in the first support assembly communicate with the liquid supply and pressurized air supply connections of the junction element. A second support assembly is arranged between each adjacent pair of spray gun modules in the array of spray gun modules for supporting the adjacent pair of spray gun modules relative to each other. Each second support assembly includes a plurality of fluid conduits for communicating fluid between the adjacent spray gun modules. One or more retaining elements secure the spray gun modules, support assemblies and junction plate in assembled relation. | 1. A modular automatic spray gun manifold comprising: a plurality of spray gun modules arranged in an array in laterally spaced relation from each other; a plurality of support assemblies with one support assembly being arranged between each adjacent pair of spray gun modules for supporting the adjacent pair of spray gun modules relative to each other, each second support assembly including a plurality of fluid conduits for communicating fluid between the adjacent spray gun modules; and one or more retaining elements extending through the spray gun modules and the support assemblies for securing the spray gun modules and support assemblies in assembled relation. 2. The spray gun manifold according to claim 1 wherein each spray gun module includes an external mix type spray nozzle and wherein one of the plurality of fluid conduits in each of the support assemblies communicates atomizing air to the spray gun modules. 3. The spray gun manifold according to claim 2 wherein the spray nozzle of each spray gun module includes an air cap and wherein one of the plurality of fluid conduits in each of the support assemblies communicates fan air to the respective air caps of the spray gun modules. 4. The spray gun manifold according to claim 1 wherein each spray gun module includes an actuator and wherein one of the plurality of fluid conduits in each of the support assemblies communicates control air to the respective actuators of the spray gun modules. 5. The spray gun manifold according to claim 1 wherein the plurality of fluid conduits of each support assembly are embedded in a block element. 7. The spray gun manifold according to claim 6 wherein each fluid conduit of each support assembly extends outwardly a distance beyond respective ends of the block element for insertion into corresponding passages in the spray gun modules with a threadless union therebetween. 8. The spray gun manifold according to claim 1 wherein the plurality of fluid conduits of each support assembly extend between end plates provided at opposite ends of the respective support assembly. 9. The spray gun manifold according to claim 1 further including a junction element arranged at an upstream end of the manifold that includes a liquid supply connection and a pressurized air supply connection. 10. The spray gun manifold according to claim 1 wherein one of the plurality of fluid conduits in each of the support assemblies is for recirculating fluid and further including a fluid return plate at a downstream end of the manifold that defines a fluid path permitting recirculation of fluid through the spray gun modules and the recirculating fluid conduits of the support assemblies in an upstream direction. 11. The spray gun manifold according to claim 1 wherein the one or more retaining elements comprises a retaining rod extending through each of the spray gun modules and each of the support assemblies. 12. A modular automatic spray gun manifold comprising: a plurality of spray gun modules arranged in an array in laterally spaced relation from each other; a junction element arranged at an upstream end of the manifold, the junction element including a liquid supply connection and a pressurized air connection; a first support assembly arranged between the junction element and a first spray gun module in the spray gun module array for supporting the first spray gun module relative to the junction element, the first support assembly including a plurality of fluid conduits for supplying fluid to the first spray gun module, the fluid conduits in the first support assembly communicating with the liquid supply and pressurized air supply connections of the junction element; one or more second support assemblies with one second support assembly being arranged between each adjacent pair of spray gun modules in the array of spray gun modules for supporting the adjacent pair of spray gun modules relative to each other, each second support assembly including a plurality of fluid conduits for communicating fluid between the adjacent spray gun modules such that fluid introduced into the manifold through the liquid supply and pressurized air supply connection of the junction element is communicated to and through each spray gun module; and one or more retaining elements for securing the spray gun modules, support assemblies and junction plate in assembled relation. 13. The spray gun manifold according to claim 12 wherein each spray gun module includes an external mix type spray nozzle and wherein one of the plurality of fluid conduits in each of the support assemblies communicates atomizing air to the spray gun modules. 14. The spray gun manifold according to claim 13 wherein the spray nozzle of each spray gun module includes an air cap and wherein one of the plurality of fluid conduits in each of the support assemblies communicates fan air to the respective air caps of the spray gun modules. 15. The spray gun manifold according to claim 12 wherein each spray gun module includes an actuator and wherein one of the plurality of fluid conduits in each of the support assemblies communicates control air to the respective actuators of the spray gun modules. 16. The spray gun manifold according to claim 12 wherein the plurality of fluid conduits of each support assembly are embedded in a block element. 17. The spray gun manifold according to claim 16 wherein each fluid conduit of each support assembly extends outwardly a distance beyond respective ends of the block element for insertion into corresponding passages in the spray gun modules with a threadless union therebetween. 18. The spray gun manifold according to claim 12 wherein the plurality of fluid conduits of each support assembly extend between end plates provided at opposite ends of the respective support assembly. 19. The spray gun manifold according to claim 12 wherein one of the plurality of fluid conduits in each of the support assemblies is for recirculating fluid and further including a fluid return plate at a downstream end of the manifold that defines a fluid path permitting recirculation of fluid through the spray gun modules and the recirculating fluid conduits of the support assemblies in the upstream direction. 20. The spray gun manifold according to claim 1 wherein the one or more retaining elements comprises a retaining rod that engages the junction element and extends through each of the support assemblies and the spray gun modules. | FIELD OF THE INVENTION The present invention relates generally to spray gun type liquid spray devices, and more particularly, to an automatic spray gun manifold having a modular construction. BACKGROUND OF THE INVENTION Modular spray gun manifold assemblies that include a plurality of laterally spaced spray guns supported in a row for discharging an elongated spray pattern are known. Such manifolds are used, for example, in pill coating machines in the pharmaceutical industry. In these applications, the manifold must be movable between a predetermined operative position relative to a rotatable pill tumbler for applying the coating and a position in which the manifold is arranged away from the tumbler to facilitate cleaning. Current manifold designs require a support structure to hold the spray guns in place. The size and weight of these manifold supports makes it difficult to mount the manifold in cantilever fashion, such as from a pivot door of a pill coating machine and to manipulate the manifold as may be required during use and/or cleaning. Moreover, current manifolds typically require a multiplicity of fluid supply lines that run along the support structure and communicate with each spray nozzle. This type of manifold not only requires extensive plumbing, but it is also difficult to clean, particularly to the extent required for use in pharmaceutical and food applications. OBJECTS AND SUMMARY OF THE INVENTION Accordingly, in view of the foregoing, an object of the present invention is to provide an improved lightweight spray gun manifold adapted for easier mounting and manipulation. Another object is to provide a modular spray gun manifold as characterized above which eliminates the necessity for massive support members that significantly increase the weight of the manifold and impede easy movement of the manifold. A further object is to provide a modular spray gun manifold of the above kind in which fluid directing conduits constitute the support structure of the manifold. Still another object is to provide a modular spray gun manifold of the foregoing type that is adapted for easy disassembly for cleaning, or for enabling a change in the number of spray guns in the manifold. Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an exemplary modular spray gun manifold in accordance with the invention. FIG. 2 is an enlarged, partially exploded perspective view of the modular spray gun manifold of FIG. 1 showing one of the spray gun modules and the adjacent supporting support assemblies. FIG. 3 is an enlarged, partially exploded perspective view of the modular spray gun manifold of FIG. 1 showing the end spray gun module and the adjacent fluid return plate. FIG. 4 is a perspective view of one of the supporting support assemblies of the modular spray gun manifold of FIG. 1. FIG. 5 is a perspective view of the body of one of the spray gun modules of the modular spray gun manifold of FIG. 1. FIG. 6 is a perspective view of the junction plate of the modular spray gun manifold of FIG. 1. FIG. 7 is a perspective view of an alternative embodiment of a modular spray gun manifold according to the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring now more particularly to FIG. 1 of the drawings, there is shown an illustrated modular spray gun manifold 10 in accordance with the invention. The manifold 10 includes a plurality of spray gun modules 11 each of which includes a rectangular block-shaped body 12, a spray nozzle assembly 13 supported at one end of the module body 12, and an actuator 14 supported at the opposite end of the module body 12. The basic structure and mode of operation of the spray gun modules are known in the art, for example, as shown in U.S. Pat. No. 5,707,010 assigned to the same assignee of the present application, the disclosure of which is incorporated herein by reference. The overall structure and mode of operation of the spray gun modules 11 should be understood to be illustrative of only one example of spray device with which the present invention may be used. The spray nozzle assembly 13 of the illustrated spray gun module 11 is an external mix type of spray nozzle, namely a nozzle in which liquid and pressurized air or other gases are mixed externally of a liquid discharge orifice to produce a predetermined atomized spray pattern. The spray nozzle assembly 13 comprises a nozzle body and an air cap 18 releaseably mounted at the discharge end of the module body by a retaining ring 19, which in this case threadably engages the module body (see FIGS. 1 and 2). As is known in the art, “atomizing” air directed through the nozzle assembly interacts with and atomizes the discharging liquid and “fan air” directed through the air cap 18 further atomizes, forms and directs the discharging liquid spray. While an external mix type nozzle is illustrated, it will be understood that the present invention is not limited to any type of spray nozzle. For example, an internal mix type spray nozzle or any other suitable spray nozzle could be used. The actuator 14, which also may be of a known type, has an end cap secured by a retaining ring that threadably engages an opposite end of the module body 12, and a valve needle with a piston that is selectively moved between valve on and off positions in a high speed cyclic mode through direction of pressurized air (i.e., control air) to the piston. While in the illustrated embodiment the spray nozzle assembly 13 and actuator 14 are individually mounted on and affixed to the module body 12, alternatively, the spray nozzle assembly and actuator may be part of a unitary removable cartridge, as disclosed in application Ser. No. 220,589 also assigned to the same assignee as the present application, the disclosure of which also is incorporated herein by reference. Of course, other types of actuators and spray nozzle assemblies could also be used and the present invention is not limited to any single type of actuator or spray nozzle. For permitting communication of liquid, atomizing air, fan air, and control air to the spray gun module 11, the module body 12 is formed with a plurality of respective fluid passages 20 extending transversely through opposite sides of the module body 12 that permit communication of fluids both to the spray nozzle assembly 13 and actuator 14 and through the module body 11 (see FIGS. 2 and 5). In this case, the module body 11 is also formed with a further return passage 20 for permitting recirculation of the liquid as explained in greater detail below. In accordance with an important aspect of the invention, the manifold 10 has a lightweight, easy to manipulate and support construction with the spray gun modules 11 being connected and supported by the fluid communicating passages or conduits connecting the modules without the necessity for massive or heavy support plates or other structure. More particularly, the manifold 10 has a relatively lightweight construction that permits easy cantilever support of the manifold from a single end thereof and which can be easily disassembled for cleaning. In the illustrated embodiment, the spray gun modules 11 are interconnected in laterally spaced apart relation by fluid communication and support assemblies 25 interposed between adjacent spray gun modules 11 (see FIG. 1). The support assemblies 25 in this case include a plurality of fluid conduits 26 for supplying liquid, atomizing air, cylinder air, and control air to the passages 20 in the module bodies as shown in FIG. 4. In the embodiment illustrated in FIGS. 1-4, the support assemblies 25 comprise blocks 28 within which the fluid conduits 26 are embedded. Preferably, the blocks 28 are made of a relatively lightweight material such as Teflon® or the like. To further reduce the weight of the blocks, the illustrated support assemblies have a pair of additional passages 29 therethrough which are not necessarily used to direct fluid. The fluid conduits 26 each preferably extend outwardly a small distance beyond the respective ends of the blocks for insertion into the passages 20 with a threadless union therebetween (see, e.g., FIG. 2). Appropriate sealing members are provided about the fluid conduits 26. In carrying out the invention, to permit communication of fluids to the support assemblies 25 and the interconnected spray gun modules 11 and to further enable cantilever support of the manifold 10, a support and junction plate 35 is mounted at an upstream end of the manifold 10. As shown in FIG. 6, the junction plate 35 in this case has an end plate portion 36 formed with a plurality of radial fluid connections 37 to which respective fluid supply lines can be connected at the end of the manifold. These connections 37 communicate with respective passages 39 that mate up with and communicate with the conduits 26 of the adjacent support assembly 25 when the manifold is assembled. For enabling cantilever support of the junction plate 35, an integrally formed mounting flange 38 (see FIG. 7) can extend in axial relation to the end plate portion 36 for coupling to a pivot door or other support structure. As shown in FIG. 3, an end plate 40 in this case is mounted against and closes the end of the last spray gun module in the downstream direction. It will be understood that fluid communicated to the radial passageways 37 of the junction plate 35 will communicate through the support assemblies to and through each spray gun module 11. To permit recirculation of fluid back through the manifold 10, a fluid return plate 50 can be provided after the last spray gun module 11 before the end plate 40 as shown in FIG. 3. In this case, the fluid return plate 50 is separated from the last spray gun module 11 by a gasket 52. The fluid return plate 50 includes a slot 54 that communicates with two of the fluid passages 20 in the last spray gun module 11 thereby establishing a path by which fluid can move between the two passages. Thus, the slot allows fluid exiting one of the passages 20 to recirculate back into the other passage 20 and from there back through the manifold 10 in the upstream direction through respective recirculation passages 20 in the other spray gun modules 11 and corresponding recirculation conduits 26 in the support assemblies 25. In further carrying out the invention, for releaseably securing the spray gun modules 11 of the manifold 10 in assembled relation to each other while permitting easy disassembly for cleaning and/or for addition or reduction in the number of spray gun modules 11, a pair of externally threaded retaining rods 42 are provided each of which extends the entire length of the manifold 10 and through the individual spray gun module bodies 12. In this case, each of the retaining rods 42 engage the junction plate 35 (see FIG. 6), extend through respective additional passages 43 of each support assembly 25 which house the rods (see, e.g., FIG. 4), through transverse passages 44 in the spray gun body 12 parallel to the fluid passages 20 (see FIG. 5), and through the end plate at the downstream end of the manifold (see FIG. 3). The passages 43 that house the retaining rods in this case do not protrude beyond the respective ends of the support assembly blocks. Wing nuts 48 are threaded onto the protruding ends of the retaining rods 42 to secure the spray gun modules 11 and support assemblies 25 in interposed relation between the retaining plate 40 and the junction plate 35 (see FIG. 1). It will be seen that by removal of the wing nuts 48 and separation of the support assemblies 25 and spray gun modules 11 by reason of their threadless unions, the manifold 10 can be easily disassembled for cleaning. Likewise, the number of spray gun modules 11 can be easily modified simply by changing the number of spray gun modules 11 and support assemblies 25 and the length of the retaining rods 42. A manifold 10 having an alternative embodiment of the support assemblies 65 is shown in FIG. 7. In the FIG. 7 embodiment, instead of a block configuration, the fluid conduits 26 associated with each of the support assemblies 65 are exposed. In the illustrated embodiment, the conduits 26 are supported relative to each other by lightweight end plates 69 are provided at opposite ends of the support assemblies 65. The junction plate 35 also has a slightly different configuration and includes a mounting flange 38. From the foregoing, it can be seen that the modular spray gun manifold of the present invention has a lightweight construction which enables its support and manipulation without the necessity for massive support bars or other structures typical of the prior art. The manifold also has a relatively simple construction which lends itself to economical manufacture, efficient cleaning, and easy modification for particular spray applications. All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. | <SOH> BACKGROUND OF THE INVENTION <EOH>Modular spray gun manifold assemblies that include a plurality of laterally spaced spray guns supported in a row for discharging an elongated spray pattern are known. Such manifolds are used, for example, in pill coating machines in the pharmaceutical industry. In these applications, the manifold must be movable between a predetermined operative position relative to a rotatable pill tumbler for applying the coating and a position in which the manifold is arranged away from the tumbler to facilitate cleaning. Current manifold designs require a support structure to hold the spray guns in place. The size and weight of these manifold supports makes it difficult to mount the manifold in cantilever fashion, such as from a pivot door of a pill coating machine and to manipulate the manifold as may be required during use and/or cleaning. Moreover, current manifolds typically require a multiplicity of fluid supply lines that run along the support structure and communicate with each spray nozzle. This type of manifold not only requires extensive plumbing, but it is also difficult to clean, particularly to the extent required for use in pharmaceutical and food applications. | <SOH> OBJECTS AND SUMMARY OF THE INVENTION <EOH>Accordingly, in view of the foregoing, an object of the present invention is to provide an improved lightweight spray gun manifold adapted for easier mounting and manipulation. Another object is to provide a modular spray gun manifold as characterized above which eliminates the necessity for massive support members that significantly increase the weight of the manifold and impede easy movement of the manifold. A further object is to provide a modular spray gun manifold of the above kind in which fluid directing conduits constitute the support structure of the manifold. Still another object is to provide a modular spray gun manifold of the foregoing type that is adapted for easy disassembly for cleaning, or for enabling a change in the number of spray guns in the manifold. Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: | 20040326 | 20060801 | 20050217 | 63604.0 | 0 | HWU, DAVIS D | MODULAR AUTOMATIC SPRAY GUN MANIFOLD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,811,058 | ACCEPTED | Intelligent end user devices for clearinghouse services in an internet telephony system | Clearinghouse services architectures that support the use of end user devices, such as personal computers, Internet Protocol (IP) phones, cable multimedia terminal adapters, and residential gateways, in an Internet telephony system. The innovative architectures include a proxy-based system model, a direct communication model, and a hybrid proxy/direct communication model. A user can operate an “intelligent” end user device. i.e., a device running a client program with knowledge of the architecture particulars, to access a clearinghouse service on an IP network. This enables the user to communicate a telephony call over the IP network and via the combination of a terminating gateway identified by the clearinghouse service and the Public Switched Telephone Network. | 1-3. (Cancelled.) 4. A computer-implemented method for providing clearinghouse services to a client device in an Internet Protocol (IP) telephony system, comprising the steps of: transmitting a communication session set-up request for a communication session to a proxy server from a client application operating on the client device, the client device and the proxy server coupled to an IP network; transmitting an authorization request from the proxy server to a clearinghouse service running on a service point coupled to the IP network, the clearinghouse service being accessible only by the proxy server and one or more gateways; transmitting an authorization response from the service point to the proxy server via the IP network, the authorization response comprising the identity of one or more terminating gateways coupled to the IP network and available to complete the communication session, and an authorization token for each identified terminating gateway; selecting one of the terminating gateways with the proxy server to complete the communication session; transmitting via the proxy server the communication session set-up request to the selected terminating gateway via the IP network; and establishing the communication session via the selected terminating gateway with the Public Switched Telephone Network (PSTN). 5. The method of claim 4, further comprising receiving user authentication information, wherein the user authentication information comprises a pass-word. 6. The method of claim 4, further comprising receiving user authentication information, wherein the user authentication information comprises payment information. 7. The method of claim 4, further comprising terminating the call set-up request if the client application is not a valid user of the services maintained at the proxy server. 8. The method of claim 4, wherein transmitting via the proxy server a communication session set-up request to the selected terminating gateway via the IP network further comprises formatting the set-up request according to one of a H.323 and SIP protocol. 9. The method of claim 4, further comprising determining if the proxy server is a valid user of the call delivery services of the selected terminating gateway and determining if an authorization token has been issued by a known and valid clearinghouse service. 10. The method of claim 4, further comprising determining if the proxy server is a valid user of the call delivery services of the selected terminating gateway and determining if an authorization token has been issued within an expiration period. 11. The method of claim 4, further comprising determining if the proxy server is a valid user of the call delivery services of the selected terminating gateway and comparing a called number and a call identifier to information maintained in an authorization token. 12. A computer-implemented method for providing clearinghouse services to a client device in an Internet Protocol (IP) telephony system, comprising the steps of: transmitting a communication session set-up request to a proxy server from the client device, the client device and the proxy server coupled to an IP network; transmitting an authorization request from the proxy server to a clearinghouse service running on a service point coupled to the IP network, the service point being inaccessible by the client application; transmitting an authorization response from the service point to the proxy server via the IP network, the authorization response comprising the identity of one or more terminating gateways coupled to the IP network and available to complete the communication session; launching a client application at the client device and routing the identity of one or more terminating gateways from the proxy server to the client application; selecting one of the terminating gateways with the client application to establish the communication session; transmitting via the client application, the communication session set-up request to the selected terminating gateway via the IP network; and establishing the communication session via the selected terminating gateway with the Public Switched Telephone Network (PSTN). 13. The method of claim 12, further comprising terminating the communication session set-up request if the client application is not a valid user of the services maintained at the proxy server. 14. The method of claim 12, further comprising determining if the proxy server is a valid user of the clearinghouse services by establishing a secure communications link between the proxy server and the service point and evaluating the proxy server with the service point. 15. The method of claim 12, wherein launching a client application at the client device further comprises dynamically constructing a web page. 16. The method of claim 12, wherein transmitting via the client application the communication session set-up request to the selected terminating gateway via the IP network further comprises formatting the set-up request according to one of a H.323 and SIP protocol. 17. The method of claim 12, further comprising receiving user authentication information, wherein the user authentication information comprises a pass-word. 18. The method of claim 12, further comprising receiving user authentication information, wherein the user authentication information comprises payment information. 19. The method of claim 18, wherein the payment information comprises a calling card number. 20. A system for providing clearinghouse services to a client device, comprising: an IP network; a proxy server; a service point; one or more gateways; a Public Switched Telephone Network (PSTN); and a client device for transmitting a communication session set-up request to the proxy server from a client application running on the client device, the client device and the proxy server coupled to the IP network; the client device operable for transmitting an authorization request to a clearinghouse service running on the service point, the clearinghouse service being accessible only by the proxy server and the one or more gateways; the service point operable for transmitting an authorization response to the proxy server and completing a communication session via the one or more terminating gateways to the Public Switched Telephone Network (PSTN). 21. The system of claim 20, wherein the authorization request comprises a called number and a call identifier. 22. The system of claim 20, wherein the authorization response comprises the identity of the one or more terminating gateways coupled to the IP network and available to establish the communication session and to deliver an authorization token for each identified terminating gateway. 23. The system of claim 20, wherein the communication session set-up request comprises a called number and user authentication information. | CROSS REFERENCE TO RELATED APPLICATION This application claims priority to U.S. Provisional Application No. 60/141,432 filed Jun. 29, 1999. FIELD OF THE INVENTION The present invention is generally directed to intelligent end user devices for use with a clearinghouse service in an Internet telephony system. More specifically described, the present invention is directed to proxy-based, direct communication, and hybrid proxy/direct model architectures for clearinghouse services in an Internet telephony system supporting communications with intelligent end user devices. BACKGROUND OF THE INVENTION Internet telephony clearinghouse services have been designed and developed for telephony services (voice and facsimile) delivered by gateways—devices that bridge Public Switched Telephone Network (PSTN) and Internet Protocol (IP) networks. A typical call scenario is supported by the clearinghouse services architecture 100 of FIG. 1. A calling party communicates with an origination gateway 115 via a telephone handset 110 connected to the PSTN 105. The origination gateway 115 uses clearinghouse services at a service point 120 coupled to an IP network 125 to identify and obtain call authorization for one or more termination gateways 130. The origination gateway 115 can select one of the identified termination gateways 130 to accept the call communication from the calling party via the IP network 125. One of the identified termination gateways 130 can complete the call communication to the called party at the handset 110′ via the PSTN 105. A key characteristic of this architecture is that all access to the clearinghouse services relies on gateways. Gateway operators are the sole users of clearinghouse services; existing services are not visible to, or directly accessible by, end users. There is a need to extend the clearinghouse architecture to support intelligent end user devices, such as personal computers, IP phones, cable multimedia terminal adapters, and residential gateways. A critical factor in such an expansion is ensuring that the resulting architecture is interoperable with existing clearinghouse services. That will give users of these devices access to existing networks for termination of their calls, and it will provide additional sources of traffic to existing networks. SUMMARY OF THE INVENTION Three different architectures can accommodate the addition of intelligent end user devices into clearinghouse service networks for an Internet telephony system-proxy-based services, direct communication, and a hybrid proxy/direct communication model. The present invention provides a proxy-based system for supporting clearinghouse services for a client device in an Internet Protocol (IP) telephony system. The IP telephony system includes at least one client device, a proxy system, such as a proxy server, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. To initiate a call communication to a called party, a client application residing at the client device sends a call set-up request to a proxy server. The call set-up request typically comprises a called number for the call communication and user authentication information. If the client application is a valid user of the services maintained at the proxy server, the proxy server transmits an authorization request to the clearinghouse service running on the service point. The authorization request typically comprises the called number and a call identifier assigned by the proxy server to the call communication. If the proxy server is a valid user of the clearinghouse services, the service point transmits an authorization response to the proxy server via the IP network. The authorization response typically comprises the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication. This authorization response may also include an authorization token for each identified terminating gateway. In response to the authorization response, the proxy server can select one of the terminating gateways to deliver the call communication. In turn, the proxy server transmits a call communication set-up request to the selected terminating gateway via the IP network. This set-up request typically comprises the called number, the call identifier, and the authorization token. If the proxy server is a valid user of the call delivery services of the selected terminating gateway, the selected terminating gateway completes call set-up operations and delivers the call communication to the Public Switched Telephone Network (PSTN). The present invention provides a direct communication model for supporting clearinghouse services for a client device in an IP telephony system. The IP telephony system includes at least one client device executing an intelligent application program, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. The user can initiate a call via the client device by entering a telephone number to be called into the client program. In response, the client program can automatically initiate a communication with the clearinghouse service operating at the service point. For example, the client application can transmit an authorization-request for a call communication to the clearinghouse service. The authorization request typically comprises a called number for the call communication and a call identifier assigned to the call communication. If the client application is a valid user of the clearinghouse services, the service point transmits an authorization response to the client application via the IP network. The authorization response typically comprises (1) the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication and (2) an authorization token for each identified terminating gateway. In response, the client application can select one of the terminating gateways to deliver the call communication. Based on this selection of a terminating gateway, the client application prepares a call communication set-up request and transmits that request to the selected terminating gateway via the IP network. The set-up request typically comprises the called number, the call identifier, and the authorization token. If the client application is a valid user of the call delivery services of the selected terminating gateway, the gateway will deliver the call communication via the PSTN to the called number. The present invention provides a hybrid proxy/direct communication model for supporting clearinghouse services for a client device in an IP telephony system. The IP telephony system includes at least one Web-enabled client device, a proxy system, such as a proxy server, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. To initiate a call communication, a client application running on the Web-enabled client device transmits a call set-up request to a proxy server. The call set-up request typically comprises a called number for the call communication and user authentication information. If the client application is a valid user of the services maintained at the proxy server, then the proxy server transmits an authorization request to the clearinghouse service running on the service point. The authorization request typically comprises the called number and a call identifier assigned to the call communication. If the proxy server is a valid user of the clearinghouse services, the service point transmits an authorization response to the proxy server via the IP network. The authorization response typically comprises (1) the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication and (2) an authorization token for each identified terminating gateway. In response to the authorization response, the proxy server can route the identity of each terminating gateway and each authorization token to the client application via the IP network. In turn, the client application can select one of the identified terminating gateways to support the completion of the call communication. Based on this selection of a terminating gateway, the client application sends a call communication set-up request to the selected terminating gateway via the IP network. The set-up request typically comprises the called number, the call identifier, and the authorization token. If the client application is a valid user of the call delivery services of the selected terminating gateway, the selected terminating gateway delivers the call communication to the called number via the PSTN. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a clearinghouse service architecture for an Internet telephony system including origination and termination gateways coupled to an Internet Protocol (IP) and the Public Switched Telephone Network (PSTN). FIG. 2 is a block diagram illustrating a proxy-based architecture for a clearinghouse service in an IP telephony system constructed in accordance with an exemplary embodiment of the present invention. FIG. 3 is a logical flow chart diagram illustrating the computer-implemented steps of a proxy-based process for an IP telephony system in accordance with an exemplary embodiment of the present invention. FIG. 4 is a block diagram illustrating a direct communication architecture for a clearinghouse service in an IP telephony system constructed in accordance with exemplary embodiment of the present invention. FIG. 5 is a logical flow chart diagram illustrating the computer-implemented steps of a direct communication process for a clearinghouse service for an IP telephony system in accordance with exemplary embodiment of the present invention. FIG. 6 is a block diagram illustrating a hybrid proxy/direct architecture for a clearinghouse service in an IP telephony system constructed in accordance with an exemplary embodiment of the present invention. FIG. 7 a logical flow chart diagram illustrating the computer-implemented steps for a hybrid proxy/direct communication process for a clearinghouse service in an IP telephony system in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS The present invention provides clearinghouse services architectures that support the use of intelligent end user devices, such as personal computers, Internet Protocol (IP) phones, cable multimedia terminal adapters, and residential gateways, in an Internet telephony system. By the use of the present invention, a user can operate an intelligent end user device to access a clearinghouse service on an existing IP network. This enables the user to communicate a telephony call over the IP network and via the combination of a terminating gateway and the Public Switched Telephone Network (PSTN). The present invention supports three separate architectures, namely a proxy-based system model, a direct communication model, and a hybrid proxy/direct communication model. Each of the clearinghouse architectures will be described in more detail below in connection with the illustrations shown in FIGS. 2-7. Proxy-Based Model End user devices can be incorporated into a clearinghouse service architecture through proxy systems. Proxy-based services interpose a proxy system between an end user device and a terminating gateway. Proxy systems typically include H.323 gatekeepers, Session Initiation Protocol (SIP) proxy servers, and proprietary devices. A proxy-based model is fundamentally the same architecture as the existing phone-to-phone architecture; proxy-based architectural elements have exact analogs in the phone-to-phone case: Phone-to-Phone Proxy-Based End User Devices Calling party's telephone end user device PSTN from calling party to network from end user device to proxy originating gateway Originating gateway proxy system The call scenario of FIG. 2 shows a representative example of proxy-based services in which the proxy system is gatekeeper compatible with the H.323 protocol. The operator of the proxy system is equivalent to the operator of an originating gateway. The key to this model is the existence of appropriate proxy systems. The proxy must interoperate with the clearinghouse service and be able to enroll with a clearinghouse service operator. The proxy must interoperate with terminating gateways. The proxy should not employ an interoperable call signaling protocol; instead, it must convey authorization tokens in an interoperable manner. The proxy must interoperate with end user devices. The protocol between end user devices and the proxy need not be the same as the protocol between the proxy and terminating gateways. Although the exemplary example of FIG. 2 illustrates an H.323 protocol implementation in both legs, end user devices could use SIP, or even a proprietary protocol to communicate with the proxy system. The proxy-based architecture 200 shown in FIG. 2 comprises an intelligent end-user device, such as the H.323 terminal 205, for communicating to a a proxy server 210 via the IP network 220. For the example shown in FIG. 2, the proxy server is implemented as an H.323 protocol-compatible gatekeeper 210 capable of communicating with a service point 215 and a terminating gateway, such as the H.323 protocol-compatible gateway 225, via the IP network 220. Although FIG. 2 shows only a single terminating gateway, those skilled in the art will appreciate that proxy-based architecture 200 can include multiple terminating gateways capable of communicating with a proxy server. The service point 215 supports clearinghouse services for the Internet telephony system by providing the proxy server 210 with both authorization information and a list identifying one or more terminating gateways for accepting an incoming call from the user of the terminal 205. Each terminating gateway 225 is coupled to the PSTN 230 to support the communication of an incoming call from the proxy server 210 to a called party at a telephone handset 235. The terminal 205 supports the operation of a client application that is configured to communicate with the proxy server 210 via the IP network 220. To initiate an outgoing call to a called party, the user can enter the telephone for the called party at the client application operating on the terminal 205. In response, the terminal 205 transmits call-related information, including the called number, to the gatekeeper 210. The call-related information can include end-user authorization information and authentication information to support a determination of whether the user is authorized to complete an Internet telephony call via the proxy server 210. The proxy server 210 completes the user validation task and, based upon validation of the user, transmits an authorization request to the service point 215 via the IP network 220. This authorization request initiates a clearinghouse service operation by the service point 215. The authorization request typically includes the called number and a call identifier to support a secure identification of the proxy server 210 as an authorized user of the clearinghouse service maintained by the service point 215. In response the to authorization request, the service point 215 determines whether the proxy server 210 is an authorized user of the clearinghouse services. If so, the service point 215 identifies each terminating gateway 225 that can accept the call to the called party from the calling party at the terminal 205. In turn, the service point 215 can transmit an authorization response to the proxy server 210 via IP Nntwork 220. The authorization response typically comprises the identity of each available terminating gateway and an authorization token for each identified terminating gateway. The identity of each terminating gateway is typically the IP address for the gateway. In response to the authorization response, the proxy server 210 can select an identified terminating gateway 225 and set-up a call for handling by the selected terminating gateway. The set-up operation is typically completed by the proxy server 210 as an H.323 protocol set-up task and includes a communication comprising the call identifier, the authorization token for the identified terminating gateway and the called number. Although the proxy-based architecture shown in FIG. 2 is compatible with the H.323 protocol, it will be appreciated that the SIP protocol can be used to support communications by the proxy server 210 with the service point 215 and each terminating gateway 225. The proxy server 210 initiates the set-up operation by sending a set-up request to the selected terminating gateway 225. The selected terminating gateway 225 will process the set-up information, including the call identifier, the authorization token, and the called number, to determine whether to accept completion of the call. The selected terminating gateway 225 will determine whether the authorization token is valid and has been issued by a known and verified clearinghouse service. In addition, the selected terminating gateway 225 will determine whether the thorization token has expired or remains within the time period authorized for completion of the call. The selected terminating gateway 225 also will determine whether the call number and the call identifier match the call information contained in the authorization token issued by the clearinghouse service. Based upon a positive response to this set of queries, the selected terminating gateway 225 will respond to the set-up communication by issuing an set-up acknowledgment to the proxy server 210. The selected terminating gateway 225 will decline the processing of the call based upon a determination that the call information forwarded by the proxy server 210 is invalid. In response to issuing the set-up acknowledgement, the terminating gateway 225 will complete the call communication to the called umber via PSTN 230. When the call is terminated by the called party at the telephone handset 235, the selected terminating gateway 225 can report the call duration to the clearinghouse service operating at the service point 215 via IP network 220. The service point 215 can confirm receipt of the call usage information by sending a confirmation message to the selected terminating gateway 225. To complete a call in the proxy-based architecture illustrated in FIG. 2, the client application operating on the terminal 205 can accept a called a number from an end-user and can communicate with a gatekeeper, such as the proxy server 210, via the IP network 220. The proxy server 210 can handle all call-related communication with the clearinghouse service maintained at the service point 215 and call processing operations with a select gateway 225. In essence, the proxy server 210 operates as a proxy for the client application at the terminal 205 by supporting all communications with the service point 215 and selected gateway 225. FIG. 3 is a logical flow chart diagram illustrating the exemplary steps completed by a proxy-based clearinghouse service for an Internet telephony system. Turning now to FIG. 3, the proxy-based process 300 is initiated at step 305 in response to the user launching the client application at a terminal. The client application is configured to communicate with a proxy server via the IP network. For example, the client application can be implemented by the “NET MEETING” software program marketed by Microsoft Corporation of Redmond, Wash. In step 310, the user can enter into the client application a telephone number for a party to be called via the IP network. The user typically enters the called number into the client application by completing a form or a web page presented to the user at the terminal 205. In step 315, the client application completes a set-up operation with the proxy server by communicating user authorization and authentication information to the proxy server via the IP network. Typical information includes a password assigned to the end-user, namely the calling party, and call payment information, such as a calling card number. The client application is preferably programmed to complete transmission of set-up to the proxy server without manual assistance by the end-user. In step 320, represented by the client application, the proxy server completes an inquiry to determine whether the calling party is a valid user of the calling services at the proxy server. If the response to the inquiry is negative, the “NO” branch is followed from step 320 to step 325 and the call is terminated. Otherwise, the “YES” branch is followed to step 330. The proxy server transmits in step 330 an authorization request to a clearinghouse service server, such as a service point coupled to the IP network. The authorization request typically includes the called number and the call identifier. In step 335, the clearinghouse service server responds to the authorization request by completing a determination of whether the proxy server is valid and authorized to access the clearinghouse services maintained at the service point. If the proxy server is not authorized to access the services, the call is terminated at step 340. A positive response to the inquiry in step 335 results in the clearinghouse service server transmitting an authorization response to the proxy server in step 345. The authorization response typically includes an identity of one or more terminating gateways to handle the call from the end-user. In addition, the authorization response can include an authorization token for each identified terminating gateway. The clearinghouse service server supports clearinghouse services for an Internet telephony system and is further described in a pending U.S. patent application assigned to the assignee of the present application Ser. No. 09/154,564 entitled “Internet Telephone Call Reporting Engine” filed on Sep. 16, 1998. The subject matter of the '564 application is hereby fully incorporated within by reference. In step 350, the proxy server selects one of the identified terminating gateways and completes a set-up operation with a selected terminating gateway. The set-up request issued by the proxy server typically comprises a call identifier, an authorization token for the selected terminating gateway, and the called number. The set-up communications between the proxy server and the selected terminating gateway can be compatible with the H.323 protocol, the SIP protocol, or other known protocols. In step 355, the selected terminating gateway responds to the set-up request by completing a set-up operation to determine whether the proxy server is valid and has proper access to the services maintained by the terminating gateway. For example, the terminating gateway determines whether the authorization token has been issued by a known and valid clearinghouse service and is within the expiration period for a call communication. In addition, the selected terminated gateway can compare the called number and the call identifier to information maintained in the authorization token to determine whether the call-related information is valid. If the response to the inquiry in step 355 is negative, the “NO” branch is followed to 360 and the call is not accepted by the selected terminating gateway. If, on the other hand, the response to the inquiry in step 355 is positive, the “YES” branch is followed to step 365 and the terminating gateway issues a set-up acknowledgement to the proxy server. The selected terminating gateway also processes the call to the called number via the PSTN for communication to the called party. In step 370, the selected terminating gateway determines whether the call has been terminated by a called or calling party. If the response to the inquiry in step 370 is negative, the “NO” branch loops back to step 370 to initiate the monitoring task again. If call service has been terminated, “YES” branch is followed from step 370 to step 375. The selected terminating gateway in step 375 reports the call duration to the clearinghouse service server via the IP network. In response, the clearinghouse service server transmits in step 780 a call termination confirmation to the selected terminating gateway via the IP network. This supports the proper invoicing of a party responsible for payment of the call service supported by the proxy-based architecture for a clearinghouse service in an Internet telephony network. Direct Communication Model The direct communication model eliminates the need for a proxy system by enabling end user devices to communicate directly with terminating gateways. In effect, the end user device acts as the combination of an originating gateway and calling user's telephone. The direct communication model requires that end user devices themselves are interoperable with the clearinghouse services (and with terminating gateways). End user devices must be able to enroll with a clearinghouse service. Although this requirement is feasible for end user devices based on personal computer platforms, it may be problematic for other devices. Simple clients (such as PDAs, for example), however, may not have the processing power to efficiently implement the cryptographic components of a clearinghouse service. Unlike proxy-based services, the direct communication model results in end users becoming customers of clearinghouse services. The sales, marketing, and support issues of this approach may be accommodated through a third-party sales agent. Other aspects are more fundamental, however, as this model can significantly increase both the number of customers and the number of enrolled devices, while at the same time reducing the average transaction volume per customer and per device. FIG. 4 illustrates the direct communication architecture for a clearinghouse service in an Internet telephony system constructed in accordance with an exemplary embodiment of the present invention. Turning now to FIG. 4, an end user device 405 can communicate directly with a clearinghouse service maintained at a service point 410 via an IP network 415. In response to call-related information provided by the service point 410, the end user device 405 can communicate with an identified gateway 420 to support the communication of a telephony call via the IP network 415. If the terminating gateway determines that the calling party at the end user device 405 is a valid user of its call handling services, the gateway 420 can communicate the call to the called party at a telephone handset 430 via the PSTN 425. For the direct communication architecture shown in FIG. 4, the end user device 405 operates in a manner similar to a source gateway of a conventional Internet telephony system. For example, the application program operating on the device 405 can accept a telephone number to be called and issues an authorization request to the service point 410 to initiate clearinghouse service operations. This authorization request typically comprises both the called number and a call identifier to support a verification of the end user by the clearinghouse service. If the clearinghouse service determines that the device 405 is authorized to access its services, the service point 410 can transmit an authorization response to the client program at the device 405 via the IP network. The authorization response typically comprises an identity of one or more available terminating gateways and an authorization token for each identified terminating gateway. The client program operating at the device 405 can select a terminating gateway for handling the call and issues a set-up request to that selected gateway via the IP network 415. This set-up request and the corresponding response by the selected terminating gateway can be implemented by the H.323 protocol or the SIP protocol. If the selected terminating gateway 420 determines that the application program at the device 405 is an authorized user of its services, the terminating gateway will issue a set-up acknowledgment message to the device 405 via the IP network 415. In turn, the selected terminating gateway 420 can communicate the call to the called party at the telephone handset 430 via the PSTN 425. FIG. 5 is a logical flow chart diagram illustrating a direct communication process for a clearinghouse service in an Internet telephony network in accordance with an exemplary embodiment of the present invention. Turning now to FIG. 5, a direct communication process 500 is initiated at step 505 in response to launching a client application at an end user device coupled to the IP network. The calling party can enter a called number into the client application at step 510. The user typically accomplishes the entry of the number to be called by entering a telephone number into a form or Web page presented by the client application at the end user device. In response to entry of the called number, the client application can send an authorization request to a clearinghouse service server operating as a service point on the IP network. The authorization request typically comprises the called number and a call identifier to support a determination by the clearinghouse service of whether the client application is authorized to access its services. An inquiry is conducted by the clearinghouse service server in step 520 to determine whether the client application is valid and authorized to access the clearinghouse services. If the response to this inquiry is negative, the “NO” branch is followed from step 520 to step 525. The call service is terminated by the clearinghouse service server in step 525. If, on the other hand, the response to the inquiry in step 520 is positive, the “YES” branch is followed from step 520 to step 530. The clearinghouse service server transmits an authorization response in step 530 to the client application residing at the end user device via the IP network. The authorization response typically includes an identification of one or more available terminating gateways and an authorization token for each terminating gateway. In response to the authorization response, the client application can select one of the identified terminating gateways to process the call on behalf of the end user. The client application completes the selection of the terminating gateway in step 535 based upon the list of available terminating gateways identified by the clearinghouse service server. The client application also issues in step 535 a set-up request to the selected terminating gateway to initiate the call processing operation. The set-up request can be formatted as an H.323-compatible or a SIP request. The set-up request typically comprises the call identifier, the authorization token for the selected terminating gateway and the called number. In step 540, the selected terminating gateway determines whether the client application is valid and authorized to access its call handling services. The validation process typically includes a determination of whether the authorization token has been issued by a known and valid clearinghouse service and whether the authorization token is within the expiration period. In addition, the terminating gateway can complete a comparison of the called number and the call ID to the authorization token to determine whether the call-related information matches content encoded within the authorization token. If the response to the inquiry in step 540 is negative, the “NO” branch is followed to step 545 and the terminating gateway terminates all call-related operations. If, on the other hand, the response to the inquiry in step 540 is positive, the terminating gateway can initiate a call to the called number via the PSTN in step 550. In step 555, the selected terminating gateway conducts a monitoring operation to determine whether the call has been terminated by one of the parties to the call. If not, the “NO” branch is followed from step 555 to step 550 to begin the monitoring process anew. If the call has been terminated, the “YES” branch is followed from step 555 to step 560. The selected terminating gateway reports the call duration to the clearinghouse service server in step 560. The clearinghouse service server can confirm termination of the call by sending a usage confirmation message to the selected terminating gateway via the IP network. Hybrid Proxy/Direct Communication Model A third architectural model for end user devices combines aspects from both proxy-based and direct communications approaches. This hybrid model relies on a proxy system, but allows the end user device to contact terminating gateways directly. FIG. 6 illustrates how a web-based application can take advantage of the hybrid model. The application program running on the end user device (which, can be implemented as a Java or ActiveX applet implementing the Session Initiation Protocol) initiates the call by contacting a web server. The web server, acting as a proxy, performs the authorization exchange with a clearinghouse service point. It passes the resulting call routing information, along with the authorization token, back to the applet at the end user's device. The end user's PC or web-enabled device contacts the terminating gateway directly. Because the end user receives routing and authorization from a web server, the end user is forced to visit the web site for each call. As a tool for enhancing “stickiness,” the entire application may be positioned as a service for web sites (especially portals) more than for end users. Also, effective integration with other features of the web site (e.g. contact managers) may allow convenience to overcome some of the objections based on the relatively poor quality of the personal computer multimedia experience. The requirements for a hybrid architecture include the existence of appropriate interoperable proxies (e.g., devices that can communicate with clients and with clearinghouse services) and end user devices that are directly interoperable with terminating gateways. It may also be the case in this approach that the proxy server cannot return an accurate usage report. If that is true, then the clearinghouse service operator must rely strictly on the terminating gateway's usage details. FIG. 6 is a block diagram illustrating the exemplary architecture for a hybrid proxy/direct communication architecture for a clearinghouse service in an Internet telephony system. Turning now to FIG. 6, the hybrid proxy/direct communication architecture includes aspects of the proxy server model illustrated in FIG. 2 and the direct communication model illustrated in FIG. 4. For the hybrid proxy/direct communication architecture 600, a web-enabled device 605, a web server 610, a service point 615 and one or more terminating gateways 625 are coupled to an IP network 620. The web-enabled device 605 can initiate a call by transmitting a call request to the web server 610. In response, the web server 610 completes call authorization tasks with the service point 615 via the IP network 620. The service point 615 maintains the clearinghouse service and is responsible for identifying available terminating gateways to accept an incoming call and to authorize call operations supported by the web browser 610 and the web-enabled device 605. For a verified call communication, the web server 610 can respond to the authorization response issued by the service point 615 by transmitting call routing the information and an authorization token to the web-enabled device 605. The web-enabled device 605 can complete call set-up operations with an identified terminating gateway 625 via the IP network 620. In response to the completion of set-up operations, the selected terminating gateway 625 can process the call for delivery to the called party at the telephone handset 635 via the PSTN 630. FIG. 7 is a logical flow chart diagram illustrating the exemplary tasks of a hybrid proxy/direct communication process for a clearinghouse service in an Internet telephony system. Turning now to the exemplary task of the hybrid proxy/direct communication process 700, a calling party can log into a proxy server via a web-enabled device. The proxy server is typically implemented by a Web server coupled to the IP network. In step 710, inquiry is conducted by the proxy server to determine whether the user of the web-enabled device is authorized to access the call-related services maintained at the proxy server. If the response to this inquiry is negative, the “NO” branch is followed from step 710 to step 715 and the process is terminated. If the user is authorized to access services at the proxy server, the “YES” branch is followed from step 710 to step 720. The proxy server creates in step 720 an authorization request based upon a telephone number to be called and a call identifier. The called number is supplied by the calling party during the log-in task completed in step 705. In step 725, the proxy server transmits the authorization request to the clearinghouse service server. The clearinghouse service server responds in step 730 by determining whether the proxy server is valid and authorized to access the clearinghouse services maintained by the service point. The authorization request issued in step 720 by the proxy server is the first indication received by the clearinghouse service that a party desires to initiate a call via the IP network. Consequently, there is a need at the service point to securely identify the proxy server as a valid user of the clearinghouse services for processing the call-related information provided by the proxy server. If the clearinghouse service cannot verify that the proxy server is a valid user of its services, the call is terminated at step 735. If the response to the inquiry in step 730 is positive, the clearinghouse service server transmits to the proxy server in step 740 the identity of one or more available terminating gateways and an authorization token for each identified gateway. This authorization response typically comprises a list of IP addresses for the available terminating gateways and an authorization token for processing each identified terminating gateway. In step 745, the proxy server launches a client application at the web-enabled device. The Web server can accomplish the launching of the client application by dynamically constructing a Web page to launch the client. For example, the “Call to: URL” command can be used to create a link to a selected terminating gateway. The “Call to: URL” command can be used with Microsoft's “NET MEETING” protocol to create the link and to provide the authorization token and the call identifier to the client application. The user at the Web-enabled device can launch the client application by “clicking” or otherwise selecting the link to the selected terminating gateway. In step 750, the client application at the web-enabled device can complete call set-up operations with the identified terminating gateway. The typical H.323 set-up operation includes the transmission of a call identifier, an authorization token, and a called number to the selected terminating gateway via the IP network. This set-up request can be formatted to comply with the H.323 protocol or the SIP protocol. In step 755, the selected terminating gateway conducts an inquiry to determine whether the set-up request issued by the client application represents a valid call service request. The terminating gateway typically validates the client application by determining whether the authorization token has been issued by a known and valid clearinghouse service and is within the expiration period. In addition, the selected terminating gateway can compare the called number and the call identifier to information encoded within the authorization token to determine whether a match exists for a valid client application. If the response to the inquiry in step 755 is negative, the “NO” branch is followed from step 755 to step 760 and the call is terminated. If the selected terminating gateway verifies that the call service request has been issued by a valid client application, the “YES” branch is followed to step 765. In step 765, the selected terminating gateway completes the call to the called number via the PSTN. In step 770, the selected terminating gateway monitors the completed call to determine whether a call service has been terminated by a party to the call. If the response to this monitoring task is negative, the “NO” loop is followed back to step 770 to continue monitoring operations. If, on the other hand, the call has been terminated, the selected terminating gateway can report the call duration to the clearinghouse service server via the IP network in step 775. In turn, the clearinghouse service server can transmit a call termination confirmation in step 780 to the selected terminating gateway. In view of the foregoing, it will be understood that the present invention provides clearinghouse services architectures that support the use of end user devices, such as personal computers, IP phones, cable multimedia terminal adapters, and residential gateways, in an Internet telephony system. A user can operate an “intelligent” end user device. i.e., a device running a client program with knowledge of the architecture particulars, to access a clearinghouse service on an IP network. This enables the user to communicate a telephony call over the IP network and via the combination of a terminating gateway identified by the clearinghouse service and the PSTN. Significantly, the use of an intelligent end user device means that the user does not require direct access to architecture information necessary to communicate with the clearinghouse service; this information is maintained at the client application or a proxy. In addition, the present invention includes the forwarding of an authorization token to a selected terminating gateway by either a client application or a proxy. This authorization token provides an advantageous method for securely verifying that the contacting entity is a valid user of the clearinghouse service. The present invention supports three innovative architectures, namely a proxy-based system model, a direct communication model, and a hybrid proxy/direct communication model. | <SOH> BACKGROUND OF THE INVENTION <EOH>Internet telephony clearinghouse services have been designed and developed for telephony services (voice and facsimile) delivered by gateways—devices that bridge Public Switched Telephone Network (PSTN) and Internet Protocol (IP) networks. A typical call scenario is supported by the clearinghouse services architecture 100 of FIG. 1 . A calling party communicates with an origination gateway 115 via a telephone handset 110 connected to the PSTN 105 . The origination gateway 115 uses clearinghouse services at a service point 120 coupled to an IP network 125 to identify and obtain call authorization for one or more termination gateways 130 . The origination gateway 115 can select one of the identified termination gateways 130 to accept the call communication from the calling party via the IP network 125 . One of the identified termination gateways 130 can complete the call communication to the called party at the handset 110 ′ via the PSTN 105 . A key characteristic of this architecture is that all access to the clearinghouse services relies on gateways. Gateway operators are the sole users of clearinghouse services; existing services are not visible to, or directly accessible by, end users. There is a need to extend the clearinghouse architecture to support intelligent end user devices, such as personal computers, IP phones, cable multimedia terminal adapters, and residential gateways. A critical factor in such an expansion is ensuring that the resulting architecture is interoperable with existing clearinghouse services. That will give users of these devices access to existing networks for termination of their calls, and it will provide additional sources of traffic to existing networks. | <SOH> SUMMARY OF THE INVENTION <EOH>Three different architectures can accommodate the addition of intelligent end user devices into clearinghouse service networks for an Internet telephony system-proxy-based services, direct communication, and a hybrid proxy/direct communication model. The present invention provides a proxy-based system for supporting clearinghouse services for a client device in an Internet Protocol (IP) telephony system. The IP telephony system includes at least one client device, a proxy system, such as a proxy server, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. To initiate a call communication to a called party, a client application residing at the client device sends a call set-up request to a proxy server. The call set-up request typically comprises a called number for the call communication and user authentication information. If the client application is a valid user of the services maintained at the proxy server, the proxy server transmits an authorization request to the clearinghouse service running on the service point. The authorization request typically comprises the called number and a call identifier assigned by the proxy server to the call communication. If the proxy server is a valid user of the clearinghouse services, the service point transmits an authorization response to the proxy server via the IP network. The authorization response typically comprises the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication. This authorization response may also include an authorization token for each identified terminating gateway. In response to the authorization response, the proxy server can select one of the terminating gateways to deliver the call communication. In turn, the proxy server transmits a call communication set-up request to the selected terminating gateway via the IP network. This set-up request typically comprises the called number, the call identifier, and the authorization token. If the proxy server is a valid user of the call delivery services of the selected terminating gateway, the selected terminating gateway completes call set-up operations and delivers the call communication to the Public Switched Telephone Network (PSTN). The present invention provides a direct communication model for supporting clearinghouse services for a client device in an IP telephony system. The IP telephony system includes at least one client device executing an intelligent application program, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. The user can initiate a call via the client device by entering a telephone number to be called into the client program. In response, the client program can automatically initiate a communication with the clearinghouse service operating at the service point. For example, the client application can transmit an authorization-request for a call communication to the clearinghouse service. The authorization request typically comprises a called number for the call communication and a call identifier assigned to the call communication. If the client application is a valid user of the clearinghouse services, the service point transmits an authorization response to the client application via the IP network. The authorization response typically comprises (1) the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication and (2) an authorization token for each identified terminating gateway. In response, the client application can select one of the terminating gateways to deliver the call communication. Based on this selection of a terminating gateway, the client application prepares a call communication set-up request and transmits that request to the selected terminating gateway via the IP network. The set-up request typically comprises the called number, the call identifier, and the authorization token. If the client application is a valid user of the call delivery services of the selected terminating gateway, the gateway will deliver the call communication via the PSTN to the called number. The present invention provides a hybrid proxy/direct communication model for supporting clearinghouse services for a client device in an IP telephony system. The IP telephony system includes at least one Web-enabled client device, a proxy system, such as a proxy server, a service point supporting a clearinghouse service and one or more terminating gateways. Each component is coupled to an IP network, such as the global Internet. To initiate a call communication, a client application running on the Web-enabled client device transmits a call set-up request to a proxy server. The call set-up request typically comprises a called number for the call communication and user authentication information. If the client application is a valid user of the services maintained at the proxy server, then the proxy server transmits an authorization request to the clearinghouse service running on the service point. The authorization request typically comprises the called number and a call identifier assigned to the call communication. If the proxy server is a valid user of the clearinghouse services, the service point transmits an authorization response to the proxy server via the IP network. The authorization response typically comprises (1) the identity of one or more terminating gateways coupled to the IP network and available to deliver the call communication and (2) an authorization token for each identified terminating gateway. In response to the authorization response, the proxy server can route the identity of each terminating gateway and each authorization token to the client application via the IP network. In turn, the client application can select one of the identified terminating gateways to support the completion of the call communication. Based on this selection of a terminating gateway, the client application sends a call communication set-up request to the selected terminating gateway via the IP network. The set-up request typically comprises the called number, the call identifier, and the authorization token. If the client application is a valid user of the call delivery services of the selected terminating gateway, the selected terminating gateway delivers the call communication to the called number via the PSTN. | 20040326 | 20081028 | 20050127 | 59216.0 | 0 | WANG, LIANG CHE A | INTELLIGENT END USER DEVICES FOR CLEARINGHOUSE SERVICES IN AN INTERNET TELEPHONY SYSTEM | SMALL | 1 | CONT-ACCEPTED | 2,004 |
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10,811,065 | ACCEPTED | Infrared reflective wall paint | Presented are methods for reducing energy consumption by coating external vertical walls of a building with a wall paint comprising reflective metal oxide pigments. Methods for painting external vertical walls as well as compositions comprising base paint combined with reflective metal oxide pigments are also presented. | 1. A method of reducing energy consumption in a building comprising: coating one or more external vertical walls of said building with a heat reflective wall paint comprising at least one heat reflective metal oxide pigment; wherein the surface temperature of the resultant coated wall is lowered such that less energy is consumed to cool the interior of said building. 2. A method of painting an external vertical wall of a building comprising: applying a heat reflective wall paint comprising at least one heat reflective metal oxide pigment to said wall, wherein said wall paint comprises at least one heat reflective metal oxide pigment. 3. The method of claim 1, wherein said heat reflective wall paint comprises titanium dioxide. 4. The method of claim 1, wherein said heat reflective metal oxide pigment comprises a solid solution having a corundum-hematite crystal lattice structure. 5. The method of claim 1, wherein said heat reflective metal oxide pigment is an oxide of a metal selected from the group consisting of aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silium, tin, vanadium, and zinc. 6. The method of claim 1, wherein said coated wall reflects light of infrared wavelengths. 7. The method of claim 6, wherein said infrared wavelength ranges from 750 to 2500 nm. 8. The method of claim 7, wherein said infrared wavelength ranges from 800 to 2450 nm. 9. The method of claim 8, wherein said infrared wavelength ranges from 900 to 2400 nm. 10. The method of claim 9, wherein said infrared wavelength ranges from 1000 to 2300 nm. 11. The method of claim 10, wherein said infrared wavelength ranges from 1500 to 2000 nm. 12. The method of claim 6, wherein said coated wall exhibits an infrared reflectance above 30%. 13. The method of claim 12, wherein said coated wall exhibits an infrared reflectance above 50%. 14. The method of claim 13, wherein said coated wall exhibits an infrared reflectance above 70%. 15. The method of claim 1, wherein the color of said heat reflective wall paint is not white. 16. The method of claim 15, wherein said heat reflective wall paint is a dark color. 17. The method of claim 16, wherein said heat reflective wall paint is black, blue, green, yellow, red, or any combination thereof. 18. The method of claim 1, wherein said heat reflective wall paint comprises from 35 to 50% solids by weight, and from 30 to 40% solids by volume. 19. The method of claim 18, wherein said heat reflective wall paint comprises from 37 to 47% solids by weight, and from 32 to 38% solids by volume. 20. The method of claim 1, wherein the surface temperature of said coated wall is lowered by at least 20° F. 21. The method of claim 20, wherein the surface temperature of said coated wall is lowered by at least 30° F. 22. The method of claim 21, wherein the surface temperature of said coated wall is lowered by at least 40° F. 23. The method of claim 22, wherein the surface temperature of said coated wall is lowered by at least 50° F. 24. A composition of matter comprising: a base paint, for application to external vertical walls, combined with at least one heat reflective metal oxide pigment. 25. The composition of claim 24, wherein said composition comprises from 35 to 50% solids by weight, and from 30 to 40% solids by volume. 26. The composition of claim 25, wherein said composition comprises from 37 to 47% solids by weight, and from 32 to 38% solids by volume. 27. A method of preparing vertical wall paint comprising: mixing at least one heat reflective metal oxide pigment with a base paint formulation. 28. The method of claim 27, wherein said vertical wall paint comprises from 35 to 50% solids by weight, and from 30 to 40% solids by volume. 29. The method of claim 28, wherein said vertical wall paint comprises from 37 to 47% solids by weight, and from 32 to 38% solids by volume. | FIELD OF THE INVENTION The present invention relates generally to the field of heat reflective compositions. The invention also pertains generally to methods of promoting energy conservation. BACKGROUND OF THE INVENTION The information provided herein and references cited are provided solely to assist the understanding of the reader, and does not constitute an admission that any of the references or information is prior art to the present invention. Occupants of buildings located in warm weather climate zones often expend substantial amounts of energy to cool the interior of the building, e.g. air conditioning. One way to reduce energy consumption and energy demand is to employ energy-saving coatings on the building's exterior. Typically, these coatings act to reduce heat load to a building by reflecting away sunlight and/or by blocking the transfer of heat. These coatings have the purpose of reducing a structure's heat gain when the weather is hot, and heat loss when weather is cold. Energy costs, in some cases, can be significantly reduced with the use of some energy-savings coatings. However, the amount saved can vary and is dependent on the building structure itself, i.e. age, condition, color, insulation already present, etc. The environment also exerts a significant influence. For instance, those in hotter climates may notice more savings than those in cooler areas. “In fact, assessing potential energy savings is somewhat of an art as well as a science” (Mills-Senn, P., “The Sun”, PWC, January-February 2004, p. 53-75; quoted citation on p. 54; the entire disclosure of which is incorporated herein by reference). Energy-savings coatings can be described in terms of its reflectivity or reflectance property, which indicates the degree to which a coating reflects light, e.g., percentage of light that is reflected away from the surface. Another characteristic property is emissivity, which can be defined as the ability of a surface to radiate or emit energy in the form of longwave infrared radiation. Emissivity is represented by a value ranging from zero to one, wherein values closer to one correlate with lower effectiveness of the surface at impeding radiant heat transfer. For example, a coating with an emittance value of 0.25 will be more effective at blocking radiant heat transfer than a coating that has an emittance value of 0.75. Energy-saving coatings are most typically applied to roofs on the roof's exterior or to its underside, and are generally referred to as “radiation control coatings” or “radiant barriers” for interior roof coatings. Additionally, energy-saving coatings can also be applied to exterior and interior walls in much the same way as those used on roofs (Mills-Senn, P., supra, see p. 53). The following are examples of energy-saving wall and/or roof coatings (Mills-Senn, P., supra, see p. 67-68). Nationwide Chemical Coating (Bradenton, Fla.) manufactures a line of elastomeric ceramic reflective wall coatings under the name Ultra Seal, Ultra Satin, and Ultra Kote. The ceramics in these coatings provide the additional benefit of dissipating heat buildup more efficiently. SPM Thermo-Shield (Custer, S.D.) manufactures wall coatings under the Thermo-Shield brand which uses hollow, vacuumed ceramic bubbles as the primary filler. The Thermo-Shield coatings are tintable, although white is the recommended color for best energy savings. Advanced Coating Systems (Atlanta, Ga.) manufactures reflective acrylic elastomeric wall coatings that are primarily white but can be tinted. These coatings dry to a rubber-like film that is flexible and water-proof. Cerama-Tech International (San Diego, Calif.) manufactures a ceramic coating that is reflective, emissive, and elastomeric, that can be sprayed onto any exterior or interior paintable surface. The coating is white but can be tinted to almost any mid-range color. Sherwin-Williams manufactures a one-part latex-based coating designed for residential attics, decking, and coated commercial metal decking. The coating, marketed under the name E-Barrier Reflective Coating, reflects radiant energy via microscopic metal particles. The following disclosures describe reflective coatings, compositions, or materials. U.S. Pat. No.4,916,014 reports infrared reflecting compositions for coating of structures exposed to sunlight which reduce heating of the structure by the sun. Infrared reflecting materials described include metals, such as noble metals, zinc, nickel, copper, or aluminum. U.S. Pat. No. 6,004,894 reports porcelain enamel compositions for use in forming infrared reflective coatings comprising a glass component and a cerium oxide component. U.S. Pat. Nos. 6,174,360 and 6,454,848 (the disclosures of which are incorporated herein by reference) report building materials, such as stucco, roofing tiles, roofing granules, roofing shingles, or brick, comprising infrared reflective pigments having a corundum-hematite crystalline structure. U.S. Pat. No. 6,468,647 report infrared reflect visually colored metal substrates or metal-coated particles prepared by burnishing colored pigments into the metal. SUMMARY OF THE INVENTION The present invention concerns methods for reducing energy consumption of a building by coating one or more external vertical walls of the building with a heat reflective wall paint. Wall paint compositions presented herein contain at least one heat reflective metal oxide pigment, and are applied to vertical walls of a building's exterior. Application of the present paint compositions to exterior vertical walls of a building provide for lower absorption of solar energy through the coated wall. This, in turn, results in lower wall surface temperatures and lower heat transfer through the coated walls. Thus, the interior temperature of the building is cooler and consequently, less energy is consumed to cool the interior of said building. Vertical walls coated with the present heat reflective wall paints can be effective in lowering cooling energy requirements. Coated walls with no or sparse amounts of insulation may exhibit greater reductions in cooling energy requirements. The phrase “energy consumption” refers to the usage or consumption of conventional forms of energy, e.g. electricity, gas, etc. Thus, the reduction of energy consumption in a building pertains to lower usage of, for example, electricity in said building. The phrase “coating” refers to applying, layering, or covering vertical walls with the present wall paint compositions. Coating of the exterior surface of vertical walls with the present wall paint compositions may be performed by any conventional means, such as with brushes, rollers, sprayers, etc. The phrase “wall paint” refers to a fluid binder liquid composition, i.e. resin and solvent, used for coating, applying, layering, or covering vertical walls. Wall paints may be clear, colored, transparent, or nearly transparent. Wall paints embrace varnishes, stains, and finishes. Wall paints may be in any suitable formulation for application to vertical walls, such as water-based, oil-based, or acrylic-based formulations. The phrase “external vertical walls” refers to the exterior surface of any upright, vertical or nearly vertical structure construction forming an exterior siding of a building. Vertical walls may be composed of masonry, wood, plaster, or any other suitable building material. Typically, a building possess at least four vertical walls. The phrase “heat reflective” refers to an ability to reflect solar light from a surface. Reflectance or reflectivity is expressed in terms of percentage of incident solar light that is reflected away from a surface. Preferably, external vertical walls coated with the present wall paint compositions exhibit an infrared reflectance above 30%, preferably above 50%, and preferably above 70%. The phrase “heat reflective” also embraces an emissivity property, defined as the ability to radiate or emit energy in the form of longwave infrared radiation. Emissivity values range from zero to one, wherein values closer to one correlate with lower effectiveness of the surface at impeding radiant heat transfer. Consequently, surfaces with low emissivity values also exhibit lower surface temperatures. Preferably, external vertical walls coated with the present wall paint compositions have lowered surface temperatures by at least 20° F., preferably by at least 30° F., preferably by at least 40° F., and preferably by at least 50° F. Factors which may affect measurements of surface temperature include, for example, angle of sunlight, time of day, time of year, and climatic conditions. The phrase “metal oxide” refers to oxygen containing species of various metals, such as aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silium, tin, vanadium, or zinc. Preferable metal oxides that may be employed according to the invention include Cr2O3, Al2O3, V2O3, Ga2O3, Fe2O3, Mn2O3, Ti2O3, In2O3, TiBO3, NiTiO3, MgTiO3, CoTIO3, ZnTiO3, FeTiO3, MnTiO3, CrBO3, NiCrO3, FeBO3, FeMoO3, FeSn(BO3)2, BiFeO3, AlBO3, Mg3Al2Si3O12, NdAlO3, LaAlO3, MnSnO3, LiNbO3, LaCoO3, MgSiO3, ZnSiO3, or Mn(Sb,Fe)O3. The phrase “corundum-hematite crystal lattice structure” refers to a discrete crystalline structure exhibited by metal oxide pigments presented herein. Corundum-hematite crystalline structures can be obtained by using certain metal oxides, or precursors thereof, which form corundum-hematite lattice as host components and incorporating into them as guest components metal oxides or precursors thereof. Such corundum-hematite crystalline structures and methods of producing metal oxides of such structures are well known in the art and are described, for example, in U.S. Pat. Nos. 6,174,360, 6,454,848, and 6,616,744, the disclosures of all of which are incorporated herein by reference. Additionally, a host component having a corundum-hematite crystalline structure which contains as a guest component one or more elements from the group consisting of aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silium, tin, vanadium, and zinc may be used in the present wall paint compositions. The phrase “infrared wavelengths” refers to wavelengths of light in the infrared region. Wavelengths in the infrared region range from 750 to 2500 nm, such as from 800 to 2450 nm, such as from 900 to 2400 nm, such as from 1000 to 2300 nm, such as from 1500 to 2000 nm. The phrase “white” refers to an achromatic color of maximum lightness, e.g. a color which reflects nearly all light of all visible wavelengths. For example, in preferred embodiments, heat reflective wall paint compositions presented herein are not white. Preferably, the present wall paints are of a dark color (i.e. of a shade tending toward black in comparison with other shades), such as black, blue, green, yellow, red, or any combination thereof. Thus, external vertical walls can be painted with a variety of colored wall paint compositions presented herein. Advantageously, external vertical walls coated with paint compositions of the present invention need not be white in order to exhibit a lower surface temperature. Multiple metal oxide pigments may be mixed together to obtain wall paint compositions of a desired hue, so long as the heat reflective property of the resultant composition is maintained. In addition, colored pigments other than heat reflective metal oxide pigments may be added to the present wall paint compositions, such as C.I. Pigment Red 202, C.I. Pigment Red 122, C.I. Pigment Red 179, C.I. Pigment Red 170, C.I. Pigment Red 144, C.I. Pigment Red 177, C.I. Pigment Red 254, C.I. Pigment Red 255, C.I. Pigment Red 264, C.I. Pigment Brown 23, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 147, C.I. Pigment Orange 61, C.I. Pigment Orange 71, C.I. Pigment Orange 73, C.I. Pigment Orange 48, C.I. Pigment Orange 49, C.I. Pigment Blue 15, C.I. Pigment Blue 60, C.I. Pigment Violet 23, C.I. Pigment Violet 37, C.I. Pigment Violet 19, C.I. Pigment Green 7, and C.I. Pigment Green 36, or a mixture or solid solution thereof. The particular choice of pigments can be selected so as to impart superior weatherability, color retention, and low gloss uniformity to coated external vertical walls when exposed to high ultra violet sunshine. In an aspect of the invention, methods of painting external vertical walls of a house by applying a heat reflective wall paint, containing at least one heat reflective metal oxide pigment, are presented herein. Preferably, such methods are used to paint the external walls of a residential building, e.g. house. The present wall paints may be applied to external vertical walls in a single coat, and can be applied with or without the use of a primer. Walls coated with the present wall paints exhibit enhanced weathering and durability, and can reduce chipping, flaking, and peeling. The present wall paints may be applied to vertical walls composed of, for example, wood, stucco, or brick. Another aspect of the invention is directed to compositions of paint for application to external vertical walls, and at least one heat reflective metal oxide pigment. Yet another aspect of the invention is directed to methods for preparing vertical wall paint by mixing at least one heat reflective metal oxide pigment to a paint formulation. In some embodiments, a synthetic flatting aid can be added to the paint formulation. As used herein, the term “flatting aid” refers to a material added to paint formulations which serve to flatten out gloss. Representative flatting aids include silicas of any grade, such as fine silica; clays, diatomaceous earth; liquid additives; or any suitable material having high oil absorption. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the invention, wall paint compositions presented herein comprise at least one heat reflective metal oxide pigment. Heat reflective metal oxide pigments that are preferably used in the present wall paint compositions are sold by Ferro Corporation (Cleveland, Ohio) as Cool Colors™ & Eclipse™ pigments. Exemplary IR reflective pigments sold by Ferro Corporation include “new black” (Ferro product no. V-799), “old black” (Ferro product no. V-797), “turquoise” (Ferro product no. PC-5686), “blue” (Ferro product no. PC-9250), “camouflage green” (Ferro product no. V-12600), “IR green” (Ferro product no. V-12650), “autumn gold” (Ferro product no. PC9158), “yellow” (Ferro product no. PC-9416), and “red” (Ferro product nos. V-13810 and V-13815). Heat reflective metal oxide pigments of the present compositions can be prepared by various methods known in the art. Preferably, these pigments are formed using one or more metal alloys that can be incorporated as cations into the corundum-hematite crystal lattice structure. For instance, one or more metal alloys is milled to a mean particle size of less than about 10 microns, mixed with other metal oxides, and then the mixture is calcined in the presence of oxygen in a rotary kiln at temperatures ranging from about 800° C. to about 1200° C. to form the pigment. U.S. Pat. No. 6,616,744, the disclosure of which is incorporated herein by reference, describes an exemplary method for forming metal oxide pigments employed in the present invention. Wall paint compositions of the present invention comprise at least one metal oxide pigment capable of reflecting light of infrared wavelengths. Spectroscopic methods for determining reflectance values of a solid substance, including metal oxide pigments, are well known in the art and include, for example, pressing a neat powder of the solid substance and placing the powder sample into a chamber of a spectrophotometer equipped with a reflectance spectroscopy accessory. Such reflectance spectroscopic methods are described, for example, in U.S. Pat. No. 6,454,848. Wall paint compositions of the present invention may be solvent-based, oil-based, or water-based. Solvent-based and oil-based wall paint formulations are well known in the art and include, for example, XL-70 with mineral spirit and toluene; styrene acrylic with aromatic 100 based solvent; vinyl acrylic with mineral spirits and aromatic 100 based solvent; and alkyd coating. Water-based wall paint formulations are well known in the art and include, for example, acrylic resin. In certain embodiments, the present wall paint compositions are water-based formulations comprising a 100% acrylic resin. Preferably, wall paints of the present invention comprise from 35 to 50% solids by weight, from 30 to 40% solids by volume, from 3 to 7% organic solvent, and from 0 to 30% weight percent pigment (pigments include metal oxide pigments, titanium dioxide, and fillers such as formed silica, titanium extenders, and clay). In certain embodiments, wall paint formulations of the invention comprise from 37 to 47% solids by weight, such as from 39 to 45% solids by weight, such as from 41 to 43% solids by weight. In certain embodiments, wall paint formulations of the invention comprise from 32 to 38% solids by volume, such as from 34 to 36% solids by volume. Preferably, wall paints of the present invention have a density from about 9.1 to about 10.8 pounds per gallon, such as from 9.5 to 10.5 pounds per gallon. Preferred wall paint formulations used according to the invention are TEX•COTE® SUPER•COTE™, which have varying sheen finishes called Satin Finish Enamel and Platinum Flat Finish, manufactured by Textured Coatings of America (Panama City, Fla.). Other preferred wall paint formulations manufactured by Textured Coatings of America include TEX•COTE® TRIM•COTE™, which have varying sheen finishes called Satin Finish and Semi-Gloss Finish. Both the SUPER•COTE™ and TRIM•COTE™ products from Textured Coatings of America comprise heat reflective metal oxide pigments, and can be used to paint external vertical walls as well as trimmings on external vertical walls. The TEX•COTE® SUPER•COTE™ and TRIM•COTE™ is a water-based system formulated with a 100% acrylic resin. Pigments in the TEX•COTE® formulation are selected to provide hide (e.g. coverage), superior weatherability, color retention and low gloss uniformity when exposed to high ultra violet exposure from sunshine. Infrared reflective pigments are added in the TEX•COTE® formulation to reduce heat built-up, to keep the coating cooler, and to save energy. Colors stay vibrant longer due to the infrared reflective pigments used in the SUPER•COTE™ and TRIM•COTE™ formulation. A synthetic flatting aid has been added to the TEX•COTE® formulation to sustain long term “satin finish”. The rheology of the TEX•COTE® system provides flow, leveling and the necessary wet edge during application. The addition of infrared reflective pigments as well as ultraviolet and visible light stabilizers improves the weatherability of the TEX•COTE® coating. Representative TEX•COTE® SUPER•COTE™ and TRIM•COTE™ formulations are described in the examples below. Wall paints of the present invention may be applied to vertical walls using a variety of well known methods, such as brush, roller, or commercial grade airless sprayer. For instance, platinum SUPER•COTE™ is normally applied at 8 mils (1 mil=0.001 inch) wet film thickness, but on heavy textures, the coating may be applied up to 10 mils. This is approximately equivalent to 2.8 to 3.8 dry mils film thickness. Coverage rates for SUPER•COTE™ vary from about 160 to about 250 square feet per gallon depending on surface porosity and texture. Representative procedures for applying SUPER•COTE™ are described in the examples below. Wall paint compositions of the present invention can further comprise various conventional paint additives, such as dispersing aids, anti-settling aids, wetting aids, thickening agents, extenders, plasticizers, stabilizers, light stabilizers, antifoams, defoamers, catalysts, texture-improving agents and/or antiflocculating agents. Conventional paint additives are well known and are described, for example, in “C-209 Additives for Paints” by George Innes, February 1998, the disclosure of which is incorporated herein by reference. The amounts of such additives are routinely optimized by the ordinary skilled artisan so as to achieve desired properties in the wall paint, such as thickness, texture, handling, and fluidity. Wall paint compositions of the present invention may comprise various rheology modifiers or rheology additives (such as acrysol), wetting agents, defoamers, dispersants and/or co-dispersants, and microbicides and/or fungicides. To achieve enhanced weatherability, the present wall paints may comprise UV (ultra-violet) absorbers such as tinuvin. Wall paint compositions of the present invention may further comprise heat reflective substances other than metal oxide pigments discussed herein. For instance, wall paint compositions may further comprise ceramic or elastomeric substances, which are heat and/or infrared reflective, so as to provide additional heat reflective benefits. Wall paint compositions presented herein may be applied as many times necessary so as to achieve sufficient coating of external vertical walls. For example, wall paint may be applied from about 8 mils to about 10 mils wet film thickness, which is equivalent to from about 2.8 to about 3.8 dry mils film thickness. Wall paint compositions presented herein may be applied to vertical walls after coating with primers. For instance, vertical walls may be painted with a primer before application of the present wall paint compositions. Exemplary primers include TEX•COTE® SUPER•COTE™ Classic Primer, a multi-functional low V.O.C. acrylic copolymer pigmented latex system. The SUPER•COTE™ primer contains rheology modifiers to provide non-sag, leveling and film build when freshly applied. This product is ready to use where uncured cementitious surfaces are common, or where excessive amounts of alkali are present in the substrate. The SUPER•COTE™ primer is also for use on wood or approved metal surfaces. Application rate is approximately 70 to 80 square feet per gallon on heavy laced stucco; approximately 80 to 100 square feet per gallon on lighter textures, and smooth surfaces (16 to 20 mils wet, 9 to 12 mils dry film thickness) via brush, spray or roller. Coverage will depend on surface porosity, and no thinning is required. Desirable results are obtained, for example, when the primer is applied with an airless sprayer, and back rolled for desired finish. Another exemplary primer which may be optionally applied to vertical walls before application of the present wall paint compositions is SUPER•COTE™ Textured Primer, a high build water based system based on a cross-linking acrylic resin binder. This cured primer membrane provides fill, texture and weatherproofing properties over cured or “green” concrete masonry surfaces. This coating can be applied, most preferably, over concrete, cement plaster, block, brick, wood, and other approved or previously painted surfaces. This textured primer may be applied at approximately 55±5 square feet/gallon. The following examples are provided to further illustrate aspects of the invention. These examples are non-limiting and should not be construed as limiting any aspect of the invention. EXAMPLE 1 Preparation of Representative Wall Paints A. Preparation of TEX•COTE® SUPER•COTE™ The SUPER•COTE™ base coat was prepared as a 100% acrylic coating having approximately 47% solids by weight, 37% solids by volume. The SUPER•COTE™ contains about 5% organic solvent, and 22% weight percent pigment (pigments include metal oxide pigments, titanium dioxide, and fillers such as formed silica, titanium extenders, and clay). The density of SUPER•COTEM is 10.1 pounds per gallon, and the pigment volume content is about 24 percent on average. Titanium levels were adjusted depending upon the final desired color to be achieved. The solids content was kept approximately the same in all SUPER•COTE™ formulations by using inert fillers. Titanium levels varied from 0% to approximately 20% by weight. Fumed silica was used to adjust gloss. Viscosity adjustments were made by adjustment with HEUR viscosity modifiers. Various colored SUPER•COTE™ formulations were achieved by combining the above described base coat with approximately 0.1- to 10 percent of metal oxide pigment(s). For a light, off white color (i.e. Pearly Gates), the following formulation, by weight, was mixed together: Base coat (20% titanium) 99.2% Nickel Antimony Titanium Yellow Rutile 0.2% Chrome Antimony Titanium Buff Rutile 0.55% Modified Hematite 0.05% For a light tan (i.e. Light Coffee) color, the following formulation, by weight, was mixed together: Base coat (3% titanium) 98.6% High IR Red Iron Oxide 0.1% Chrome Antimony Titanium Buff Rutile 0.8% Pigment Green Cobalt Chrome 0.5% For a medium to dark gray color (i.e. Slate Gray) the following formulation, by weight, was mixed together: Base Coat (3% titanium) 93.8% High IR Red Iron Oxide 0.5% Pigment Green 26 Cobalt Chrome 3.1% Modified Hematite 2.6% For a black color (i.e. Onyx Black), the following formulation, by weight, was mixed together: Base Coat (0% titanium) 90% Modified Hematite 10% B. Preparation of TEX•COTE® TRIM•COTE™ The TRIM•COTE™ basecoat is prepared as a 100% acrylic coating having approximately 43% solids by weight, 36 % solids by volume. The TRIM•COTE™ contains about 5% organic solvent, and 22% weight percent pigment (pigments include metal oxide pigments, titanium dioxide, and fillers such as formed silica, titanium extenders, and clay). The density of TRIM•COTE™ is about 9.6 pounds per gallon, and the pigment volume content is about 10 percent on average. Titanium levels are adjusted depending upon the final desired color to be achieved. The solids content is kept approximately the same in all TRIM•COTE™ formulations by using inert fillers. Titanium levels vary from 0% to approximately 20% by weight. Fumed silica is used to adjust gloss. Viscocity adjustments are made by adjustment with HEUR viscosity modifiers. Various colored TRIM•COTE™ formulations are achieved by combining the above described basecoat with approximately 0.1 to 10 percent of metal oxide pigment(s). Colored formulations for TRIM•COTE™ are prepared in the same manner used for SUPER•COTE™. EXAMPLE 2 Application of Representative Paints to Vertical Walls A. Installation TEX•COTE” SUPER•COTE™ can be applied by brush, roller, or commercial grade airless. Coverage rates vary between 160 to 250 square feet per gallon, depending on surface porosity and texture. Commercial grade airless tip sizes that can be used are 0.017 to 0.019. B. Surface Preparation All surfaces are sound, clean, and dry prior to application of TEX•COTE® SUPER•COTE™. All loose, flaking, or oxidized paint are removed from surface by sand blasting, water blasting, wire brushing, or scraping. Large cracks, holes and voids are filled in with cement patching compounds. Texture of patch matches the existing surface. Cracks less than ⅛″ (3.2 mm) are filled. All surfaces are primed with SUPER•COTE™ CLASSIC or Textured Primer, or other manufacturer approved primers for non-masonry surfaces. C. Application Over a dry, clean, properly prepared surface, SUPER•COTE™ is applied at an application rate of approximately 160 to 250 square feet per gallon. Application is at uniform film thickness over the entire vertical wall. A wet edge is maintained during spraying (brushing or rolling) at all times. To prevent lap marks, starting and stopping midway is avoided on vertical walls. On large areas, two people spray simultaneously to avoid lap marks and spray patterns. When rolling on SUPER•COTE™, a fully loaded roller is applied in vertical strokes initially, and is then cross rolled for even film, ending with vertical strokes. To prevent lap marks, application proceeded as above and continued to a “natural break” such as panel edge, seam, or corner. D. Drying/Curing Times Drying to the touch occurs in approximately 2 hrs. after application. For drying to hardness, a minimum of approximately 24 hrs. is needed after application. After 24 hours, residual matters in film will continue to cure with additional days of drying. Times are based on ideal weather. EXAMPLE 3 Comparison Study in Two Representative Climate Zones The following is an exemplary theoretical analysis of the use of the wall paints described herein. A comparison study of two test buildings, each in a representative climate zones, Miami, Fla. and Los Angeles, Calif., is conducted. Each of the four faces of the test building is divided into two equal area and each area is coated either with a heat reflective wall paint of the present invention or a non-heat reflective wall paint of the same color. Each test building is monitored for at least one year. Reflectance and emittance measurements are collected semi-annually. Temperatures on the wall surfaces and inside the building is measured and logged into a data acquisition system. Heat flow measurements are obtained by heat flux transducers, which are embedded in the walls. Total air-conditioning, as well as ancillary building power demand are recorded to document the cost savings for walls coated with heat reflective wall paints of the present invention. A pyranometer is mounted proximally to the test building to monitor solar irradiance. Thermal scans of the test building are taken to determine the relative heat influx of the two different wall systems. Thermal scans are also used to record the overall thermal performance as the wall system ages. Tables 1 and 2 below summarize the predicted energy estimates for cooling and supply fans for test houses in Los Angeles and Miami, respectively. These predicted estimates are generated using an hourly building energy simulation program called VisualDOE 3.1. This programs is a whole building energy analysis program that uses hourly weather data to calculate energy consumption due to internal and external energy loads. TABLE 1 PREDICTED COOLING AND FAN ENERGY IN LOS ANGELES TEST BUILDING Cooling Energy Fan Energy Total Energy (kWh) (kWh) (kWh) Conventional 5,903 1,762 7,665 gray paint Gray colored 4,483 1,407 5,890 wall paint of the invention Savings 1,420 355 1,775 (24%) (23.2%) TABLE 2 PREDICTED COOLING AND FAN ENERGY IN MIAMI TEST BUILDING Cooling Energy Fan Energy Total Energy (kWh) (kWh) (kWh) Conventional 11,626 2,592 14,218 gray paint Gray colored 11,354 2,528 13,882 wall paint of the invention Savings 272 64 336 (2.3%) (2.4%) Wall paints of the present invention show a lower cooling energy requirement than conventional paints of the same color in both Los Angeles and Miami. Overall, the total annual energy savings for the test building in Los Angeles is 24%, whereas the total energy savings in Miami is 2.3%. Maximum energy savings in walls coated with wall paints of the present can occur in the summer months of May through September when cooling energy is typically used most. The invention illustratively described herein may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein. The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The contents of the articles, patents, and patent applications, and all other documents and electronically available information mentioned or cited herein, are hereby incorporated by reference in their entirety to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. Applicants reserve the right to physically incorporate into this application any and all materials and information from any such articles, patents, patent applications, or other documents. The inventions illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising”, “including,” containing”, etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the inventions embodied therein herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention. The invention has been described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group. Other embodiments are set forth within the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The information provided herein and references cited are provided solely to assist the understanding of the reader, and does not constitute an admission that any of the references or information is prior art to the present invention. Occupants of buildings located in warm weather climate zones often expend substantial amounts of energy to cool the interior of the building, e.g. air conditioning. One way to reduce energy consumption and energy demand is to employ energy-saving coatings on the building's exterior. Typically, these coatings act to reduce heat load to a building by reflecting away sunlight and/or by blocking the transfer of heat. These coatings have the purpose of reducing a structure's heat gain when the weather is hot, and heat loss when weather is cold. Energy costs, in some cases, can be significantly reduced with the use of some energy-savings coatings. However, the amount saved can vary and is dependent on the building structure itself, i.e. age, condition, color, insulation already present, etc. The environment also exerts a significant influence. For instance, those in hotter climates may notice more savings than those in cooler areas. “In fact, assessing potential energy savings is somewhat of an art as well as a science” (Mills-Senn, P., “The Sun”, PWC, January-February 2004, p. 53-75; quoted citation on p. 54; the entire disclosure of which is incorporated herein by reference). Energy-savings coatings can be described in terms of its reflectivity or reflectance property, which indicates the degree to which a coating reflects light, e.g., percentage of light that is reflected away from the surface. Another characteristic property is emissivity, which can be defined as the ability of a surface to radiate or emit energy in the form of longwave infrared radiation. Emissivity is represented by a value ranging from zero to one, wherein values closer to one correlate with lower effectiveness of the surface at impeding radiant heat transfer. For example, a coating with an emittance value of 0.25 will be more effective at blocking radiant heat transfer than a coating that has an emittance value of 0.75. Energy-saving coatings are most typically applied to roofs on the roof's exterior or to its underside, and are generally referred to as “radiation control coatings” or “radiant barriers” for interior roof coatings. Additionally, energy-saving coatings can also be applied to exterior and interior walls in much the same way as those used on roofs (Mills-Senn, P., supra, see p. 53). The following are examples of energy-saving wall and/or roof coatings (Mills-Senn, P., supra, see p. 67-68). Nationwide Chemical Coating (Bradenton, Fla.) manufactures a line of elastomeric ceramic reflective wall coatings under the name Ultra Seal, Ultra Satin, and Ultra Kote. The ceramics in these coatings provide the additional benefit of dissipating heat buildup more efficiently. SPM Thermo-Shield (Custer, S.D.) manufactures wall coatings under the Thermo-Shield brand which uses hollow, vacuumed ceramic bubbles as the primary filler. The Thermo-Shield coatings are tintable, although white is the recommended color for best energy savings. Advanced Coating Systems (Atlanta, Ga.) manufactures reflective acrylic elastomeric wall coatings that are primarily white but can be tinted. These coatings dry to a rubber-like film that is flexible and water-proof. Cerama-Tech International (San Diego, Calif.) manufactures a ceramic coating that is reflective, emissive, and elastomeric, that can be sprayed onto any exterior or interior paintable surface. The coating is white but can be tinted to almost any mid-range color. Sherwin-Williams manufactures a one-part latex-based coating designed for residential attics, decking, and coated commercial metal decking. The coating, marketed under the name E-Barrier Reflective Coating, reflects radiant energy via microscopic metal particles. The following disclosures describe reflective coatings, compositions, or materials. U.S. Pat. No.4,916,014 reports infrared reflecting compositions for coating of structures exposed to sunlight which reduce heating of the structure by the sun. Infrared reflecting materials described include metals, such as noble metals, zinc, nickel, copper, or aluminum. U.S. Pat. No. 6,004,894 reports porcelain enamel compositions for use in forming infrared reflective coatings comprising a glass component and a cerium oxide component. U.S. Pat. Nos. 6,174,360 and 6,454,848 (the disclosures of which are incorporated herein by reference) report building materials, such as stucco, roofing tiles, roofing granules, roofing shingles, or brick, comprising infrared reflective pigments having a corundum-hematite crystalline structure. U.S. Pat. No. 6,468,647 report infrared reflect visually colored metal substrates or metal-coated particles prepared by burnishing colored pigments into the metal. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention concerns methods for reducing energy consumption of a building by coating one or more external vertical walls of the building with a heat reflective wall paint. Wall paint compositions presented herein contain at least one heat reflective metal oxide pigment, and are applied to vertical walls of a building's exterior. Application of the present paint compositions to exterior vertical walls of a building provide for lower absorption of solar energy through the coated wall. This, in turn, results in lower wall surface temperatures and lower heat transfer through the coated walls. Thus, the interior temperature of the building is cooler and consequently, less energy is consumed to cool the interior of said building. Vertical walls coated with the present heat reflective wall paints can be effective in lowering cooling energy requirements. Coated walls with no or sparse amounts of insulation may exhibit greater reductions in cooling energy requirements. The phrase “energy consumption” refers to the usage or consumption of conventional forms of energy, e.g. electricity, gas, etc. Thus, the reduction of energy consumption in a building pertains to lower usage of, for example, electricity in said building. The phrase “coating” refers to applying, layering, or covering vertical walls with the present wall paint compositions. Coating of the exterior surface of vertical walls with the present wall paint compositions may be performed by any conventional means, such as with brushes, rollers, sprayers, etc. The phrase “wall paint” refers to a fluid binder liquid composition, i.e. resin and solvent, used for coating, applying, layering, or covering vertical walls. Wall paints may be clear, colored, transparent, or nearly transparent. Wall paints embrace varnishes, stains, and finishes. Wall paints may be in any suitable formulation for application to vertical walls, such as water-based, oil-based, or acrylic-based formulations. The phrase “external vertical walls” refers to the exterior surface of any upright, vertical or nearly vertical structure construction forming an exterior siding of a building. Vertical walls may be composed of masonry, wood, plaster, or any other suitable building material. Typically, a building possess at least four vertical walls. The phrase “heat reflective” refers to an ability to reflect solar light from a surface. Reflectance or reflectivity is expressed in terms of percentage of incident solar light that is reflected away from a surface. Preferably, external vertical walls coated with the present wall paint compositions exhibit an infrared reflectance above 30%, preferably above 50%, and preferably above 70%. The phrase “heat reflective” also embraces an emissivity property, defined as the ability to radiate or emit energy in the form of longwave infrared radiation. Emissivity values range from zero to one, wherein values closer to one correlate with lower effectiveness of the surface at impeding radiant heat transfer. Consequently, surfaces with low emissivity values also exhibit lower surface temperatures. Preferably, external vertical walls coated with the present wall paint compositions have lowered surface temperatures by at least 20° F., preferably by at least 30° F., preferably by at least 40° F., and preferably by at least 50° F. Factors which may affect measurements of surface temperature include, for example, angle of sunlight, time of day, time of year, and climatic conditions. The phrase “metal oxide” refers to oxygen containing species of various metals, such as aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silium, tin, vanadium, or zinc. Preferable metal oxides that may be employed according to the invention include Cr 2 O 3 , Al 2 O 3 , V 2 O 3 , Ga 2 O 3 , Fe 2 O 3 , Mn 2 O 3 , Ti 2 O 3 , In 2 O 3 , TiBO 3 , NiTiO 3 , MgTiO 3 , CoTIO 3 , ZnTiO 3 , FeTiO 3 , MnTiO 3 , CrBO 3 , NiCrO 3 , FeBO 3 , FeMoO 3 , FeSn(BO 3 ) 2 , BiFeO 3 , AlBO 3 , Mg 3 Al 2 Si 3 O 12 , NdAlO 3 , LaAlO 3 , MnSnO 3 , LiNbO 3 , LaCoO 3 , MgSiO 3 , ZnSiO 3 , or Mn(Sb,Fe)O 3 . The phrase “corundum-hematite crystal lattice structure” refers to a discrete crystalline structure exhibited by metal oxide pigments presented herein. Corundum-hematite crystalline structures can be obtained by using certain metal oxides, or precursors thereof, which form corundum-hematite lattice as host components and incorporating into them as guest components metal oxides or precursors thereof. Such corundum-hematite crystalline structures and methods of producing metal oxides of such structures are well known in the art and are described, for example, in U.S. Pat. Nos. 6,174,360, 6,454,848, and 6,616,744, the disclosures of all of which are incorporated herein by reference. Additionally, a host component having a corundum-hematite crystalline structure which contains as a guest component one or more elements from the group consisting of aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silium, tin, vanadium, and zinc may be used in the present wall paint compositions. The phrase “infrared wavelengths” refers to wavelengths of light in the infrared region. Wavelengths in the infrared region range from 750 to 2500 nm, such as from 800 to 2450 nm, such as from 900 to 2400 nm, such as from 1000 to 2300 nm, such as from 1500 to 2000 nm. The phrase “white” refers to an achromatic color of maximum lightness, e.g. a color which reflects nearly all light of all visible wavelengths. For example, in preferred embodiments, heat reflective wall paint compositions presented herein are not white. Preferably, the present wall paints are of a dark color (i.e. of a shade tending toward black in comparison with other shades), such as black, blue, green, yellow, red, or any combination thereof. Thus, external vertical walls can be painted with a variety of colored wall paint compositions presented herein. Advantageously, external vertical walls coated with paint compositions of the present invention need not be white in order to exhibit a lower surface temperature. Multiple metal oxide pigments may be mixed together to obtain wall paint compositions of a desired hue, so long as the heat reflective property of the resultant composition is maintained. In addition, colored pigments other than heat reflective metal oxide pigments may be added to the present wall paint compositions, such as C.I. Pigment Red 202, C.I. Pigment Red 122, C.I. Pigment Red 179, C.I. Pigment Red 170, C.I. Pigment Red 144, C.I. Pigment Red 177, C.I. Pigment Red 254, C.I. Pigment Red 255, C.I. Pigment Red 264, C.I. Pigment Brown 23, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 147, C.I. Pigment Orange 61, C.I. Pigment Orange 71, C.I. Pigment Orange 73, C.I. Pigment Orange 48, C.I. Pigment Orange 49, C.I. Pigment Blue 15, C.I. Pigment Blue 60, C.I. Pigment Violet 23, C.I. Pigment Violet 37, C.I. Pigment Violet 19, C.I. Pigment Green 7, and C.I. Pigment Green 36, or a mixture or solid solution thereof. The particular choice of pigments can be selected so as to impart superior weatherability, color retention, and low gloss uniformity to coated external vertical walls when exposed to high ultra violet sunshine. In an aspect of the invention, methods of painting external vertical walls of a house by applying a heat reflective wall paint, containing at least one heat reflective metal oxide pigment, are presented herein. Preferably, such methods are used to paint the external walls of a residential building, e.g. house. The present wall paints may be applied to external vertical walls in a single coat, and can be applied with or without the use of a primer. Walls coated with the present wall paints exhibit enhanced weathering and durability, and can reduce chipping, flaking, and peeling. The present wall paints may be applied to vertical walls composed of, for example, wood, stucco, or brick. Another aspect of the invention is directed to compositions of paint for application to external vertical walls, and at least one heat reflective metal oxide pigment. Yet another aspect of the invention is directed to methods for preparing vertical wall paint by mixing at least one heat reflective metal oxide pigment to a paint formulation. In some embodiments, a synthetic flatting aid can be added to the paint formulation. As used herein, the term “flatting aid” refers to a material added to paint formulations which serve to flatten out gloss. Representative flatting aids include silicas of any grade, such as fine silica; clays, diatomaceous earth; liquid additives; or any suitable material having high oil absorption. detailed-description description="Detailed Description" end="lead"? | 20040326 | 20070102 | 20050929 | 60677.0 | 2 | BASHORE, ALAIN L | INFRARED REFLECTIVE WALL PAINT | SMALL | 0 | ACCEPTED | 2,004 |
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10,811,294 | ACCEPTED | SYNTHESIS OF ION IMPRINTED POLYMER PARTICLES | Ion imprinted polymer materials are synthesized containing metal ion recognition sites. These particles are synthesized by copolymerizing with functional and cross linking monomers in presence of at least one imprint metal ion in the form of ternary complex. The polymerization was carried out by □-irradiation (in the absence of initiator) or photochemical and thermal polymerization (in presence of initiator, AIBN). These materials were ground and sieved after drying to obtain erbium ion imprinted polymer particles. The erbium ion was removed from the polymer particles by leaching with mineral acid which leaves cavities/binding sites in the polymer particles. The resultant polymer particles can be used as solid phase extractants for selective enrichment of erbium ions from dilute aqueous solutions. | 1. A process for the synthesis of ion imprinted polymer particles for solid phase extraction preconcentration of erbium ions, the process consisting essentially of: (a) forming a mixed ligand ternary complex of erbium imprint ion with 5,7-dichloroquinoline-8-ol and 4-vinyl pyridine; (b) dissolving the ternary complex in a suitable porogen to form a pre-polymerizing mixture; (c) combining the mixture of step (b) with a functional monomer and a crosslinking monomer and polymerizing by γ-irradiation or by photochemical and thermal polymerization to obtain a polymer material; (d) grinding and sieving of polymer material obtained in (c) to prepare erbium ion imprinted polymer particles; (e) selective leaching of imprint ion embedded materials in the polymer particles of (d) using a mineral acid. 2. The process as claimed in claim 1 wherein the γ-irradiation is carried out as a function of methyl methacrylate (functional monomer) concentration. 3. The process as claimed in claim 1 wherein the photochemical polymerization is carried out as a function of time of UV irradiation. 4. The process as claimed in claim 1 wherein the thermal polymerization is carried out as a function of ethyleneglycoldimethacrylate (crosslinking monomer) concentration. 5. The process as claimed in claim 1 wherein the functional monomer is selected from the group consisting of 4-vinylpyridine and methylmethacrylate. 6. The process as claimed in claim 1 wherein the crosslinking monomer comprises ethylene glycol dimethacrylate. 7. The process as claimed in claim 1 wherein the reaction is carried out using 2,2′-azobisisobutyronitrile is used as initiator in step (c). 8. The process as claimed in claim 1 wherein the grinding and sieving in step (d) is carried out after drying of the erbium ion imprinted polymer materials. 9. The process as claimed in claim 1 wherein the mineral acid used for leaching comprises HCl. 10. The process of claim 1, wherein the ion imprinted polymer particles are used for separation of erbium ion from dilute aqueous solution, said process further comprising: adding the polymer particles to a dilute aqueous solution containing erbium ion; and allowing the erbium ion within the dilute aqueous solution to selectively bind the polymer particles for separation of erbium ion from solution. | FIELD OF THE INVENTION The present invention relates to the synthesis of ion imprinted polymer particles for solid phase extractive preconcentration of erbium ions and to a process thereof. Ion imprinted polymer particles have been prepared by radiochemical, photochemical and thermal polymerization. BACKGROUND OF THE INVENTION Monazite sand is processed by a series of beneficiation processes to produce lighter, middle and heavier rare earth chloride fractions. The last fraction contains 55-60% Y2O3 along with Dy, Gd and Er as impurities. The preparation of 99.9-99.999% Y2O3 gains importance as it is widely used in manufacture of lasers, superconducting materials and colour T.V. Phosphors. Hence, the separation of Dy, Gd and Er is an essential prerequisite to prepare such high purity Y2O3. The three different polymerization processes described in this patent enables the separation of erbium from Y2O3. Enantiomer Separation Reference is made to Mark et al., WO 98/07671; 1998, who have prepared imprinted polymers for the separation of optically active compounds of ibuprofen, naproxen and ketoprofen into their respective enantiomers. Reference is made to Mosbach et al., U.S. Pat. No. 6,316,235; 2001 who have prepared magnetically susceptible components by copolymerizing one or more functional monomers and crosslinking monomer in presence of at least one imprint molecule and at least one magnetically susceptible component such as iron oxide or nickel oxide. The imprint molecule was subsequently removed to form molecular memory recognition sites. These particles are used for selective separation of two different enantiomeric forms. Reference is also made to Arnold et al., U.S. Pat. No. 5,786,427; 1998, who prepared solid phase extractant materials which include polymeric matrix containing one or more metallic complexes by molecular imprinting, which selectively binds only one enantiomer of the optically active amino acid or peptide. Reference is made to Fischer et al, U.S. Pat. No. 5,461,175; 1995 who synthesized chiral chromatographic materials for separating enantiomers of a derivative of an aryloxipropanol amine. Sensors Reference is made to Arnold et al., U.S. Pat. No. 6,063,637; 2000 who have developed sensors composed of a metal complex that binds the target molecule and releases a proton or includes an exchangeable ligand which is exchanged for the target molecule during the binding interaction between the metal complex and target molecule. These sensors are meant for detecting the presence of sugars and other metal binding analytes. Reference is made to Yan et al., U.S. Pat. No. 5,587,273; 1996 who prepared molecular imprinted substrate and sensors by first forming a solution comprising a solvent and (a) polymeric material capable of undergoing an addition reaction with nitrene, (b) a cross-linking agent, (c) a functional monomer and (d) an imprinting molecule. Other Applications of Molecular Imprinting Reference is made to Markowitz et al, U.S. Pat. No. 6,310,110; 2001 who synthesized molecular imprinted porous structures by self assembling surfactant analogue to create at least one supramolecular structure having exposed imprint groups. The imprinted porous structure is formed by adding reactive monomers to the mixture and allowing the monomers to polymerize with the supramolecular structure serving as the template. Reference is also made to Sasaki et al., U.S. Pat. No. 6,057,377; 2000 who have developed a method for molecular imprinting on the surface of a sol-gel material, solvent, an imprinting molecule to form the molecular imprinted metal oxide sol-gel materials. Reference is made to Mosbach and Olof, U.S. Pat. No. 6,255,461; 2003 who prepared artificial antibodies by molecular imprinting, wherein methacrylic acid, ethylene glycoldimethacrylate and a corticosteroid print molecule are combined to form artificial antibody. These antibodies can be used in separation and analytical procedures. Reference is also made to Magnus et al., U.S. patent application 2003-049970; 2003 who have prepared selective adsorption material which can be used for purification or analysis of biological macromolecules. Ion Imprinting—Anions Reference is made to Murray, U.S. patent application 2003-113234; 2003 who has prepared molecularly imprinted polymer membranes for selectively collecting phosphate, nitrate and ferric ions. These membranes are prepared by copolymerizing a matrix monomer, cross linking monomer, ion imprinting complex, permeability agent and polymerization initiator, after which the ions of the ion imprinting complex and permeability agent are removed. The permeability agent creates channels in the membrane permitting membrane to communicate with the exterior surface of the the ion binding sites in the membrane. Murray, U.S. patent application 2003-059346; 2003 addresses the removal of phosphate/nitrate anions using selectively permeable polymer membrane. The selective binding site is prepared by ferric ion imprinting. Permeability is improved by using a polyester that associates with metal ions; the polyester is removed from the membrane by the same acid treatment used to remove ferric ion. The polyester creates channels directing the ion migration to the imprinted sites, thus, increasing the flux but maintaining selectivity. Ion Imprinting—Cations Reference is made to Singh et al, U.S. Pat. No. 6,248,842; 2001 who produced selective, crosslinked chelating polymers by substituting an acyclic chelating agent with a polymerizable functional group. The resulting substituted acyclic chelating agent is then complexed with the target metal ion, i.e. copper. A crosslinkable monomer is then added and the complexed material is crosslinked. The complexed metal is then removed, providing a crosslinked polymeric chelating agent that has been templated for the target metal ion. Reference is made to John et al, WO 99/15707; 1999 relating to the detection and extraction of uranyl ion by polymer imprinting wherein the complexable functionality is of the formula CTCOOH, where T is a hydrogen or any halogen (preferably chlorine), methyl and halogen substituted form thereof or COOH or PhCOOH. Gladis and Rao also teach synthesis of ion imprinted polymers for solid phase extractive preconcentration/separation of uranyl ion from host of tetravalent, tervalent and bivalent inorganic ions from both aqueous and synthetic sea water solutions. They form ternary mixed ligand complex of imprint ion with quinoline-8-ol or its dihalo derivatives and 4-vinyl pyridine in presence of styrene and divinyl benzene as functional and crosslinking monomers. Reference is made to Dai et al, U.S. Pat. No. 6,251,280; 2001 who prepared mesophorous sorbent materials by ion imprinting technique for the separation of inorganics using bifunctional ligands such as amines, thiols, carboxylic acids, sulphonic acids and phosphonic acids. Carboxylic acid groups on bifunctional ligands are used during the formation of mesophoric sorbent materials specific for erbium template ion. Rao et al [Trends in Anal. Chem.; 2003] have reviewed the preparation of tailored materials for preconcentration/separation of metals by ion imprinted polymers for solid phase extraction (IIP-SPE). Ion imprinted polymer (IIP) materials with nanopores were prepared by formation of ternary complex of palladium imprint ion with dimethyl glyoxime and 4-vinyl pyridine and thermally copolymerizing with styrene and divinyl benzene in presence of 2,2′-azobisisobutyronitrile using cyclohexanol as porogen [Sobhi et al, Anal. Chim. Acta, 488 (2003) 173-182]. Cation imprinted SPE materials for separation of La and Gd based on diethylenetriaminepentaacetic acid (DTPA) derivatives have been prepared. Imprinting effect was observed with materials prepared in the presence of Gd salts and exhibited high efficiency and selectivity than the corresponding blank polymers [Garcia et al, Tetrahedran Lett:, 39 (1998) 8651]. The functionalized monomer of DTPA was copolymerized with commercially available divinyl benzene (DVB) containing 45% ethyl styrene in presence of Gd3+ salt. The resulting IIP was found to be more selective for Gd compared to La [Vigneau et al, Anal. Chim. Acta, 435 (2001) 75]. These selective studies were extended to determine SGd/Eu and SGd/Lu using Gd imprinted IIP [Logneau et al, Chem. Lett. (2002) 202]. Biju et al [Anal. Chim. Acta, 478 (2003) 43-51] have synthesized Dy(III) IIP particles by copolymerizing styrene (functional monomer) in presence of DVB as crosslinking monomer. Some authors [Talanta, 60 (2003) 747-754] have reported improved selectivity coefficients for Dy over La, Nd, Y and Lu on post γ-irradiation of Dy IIP particles. Molecular imprinted polymer particles prepared are widely used in separation of enantiomers, structurally related drugs, amino acid derivatives, nucleotide base derivatives etc. Thus, they find widespread use in chemical and pharmaceutical industries, water purification and waste treatment. On the other hand, the preparation of ion imprinted polymer particles are not that popular for the separation of closely related inorganic ions. The patent by Dai et al [U.S. Pat. No. 6,251,280; 2001] alone addresses this problem but is too general and do not involve separation of Er from closely related lanthanides. OBJECTS OF THE INVENTION The main object of the present investigation is to prepare Erbium IIP materials by γ-irradiation in presence of varying amounts of methyl methacrylate (MMA) (functional monomer). It is another object of the invention to provide a process for the preparation of Erbium IIP materials by photochemical polymerization as a function of time of exposure. It is another object of the invention to provide a process for the preparation of Erbium IIP materials by thermal polymerization as a function of EGDMA concentration (crosslinking monomer). Yet another object of the present invention is to preconcentratively separate Erbium from other selected lanthanides using IIP particles through solid phase extraction. SUMMARY OF THE INVENTION Accordingly the present invention provides a process for the synthesis of ion imprinted polymer particles for solid phase extraction preconcentration of erbium ions which comprises: (a) forming a mixed ligand ternary complex of erbium imprint ion with 5,7-dichloroquinoline-8-ol and 4-vinyl pyridine; (b) dissolving the ternary complex in a suitable porogen to form a pre-polymerizing mixture; (c) combining the mixture of step (b) with a functional monomer and a crosslinking monomer and polymerizing by γ-irradiation or by photochemical and thermal polymerization to obtain a polymer material; (d) grinding and sieving of polymer material obtained in (c) to prepare erbium ion imprinted polymer particles; (e) selective leaching of imprint ion embedded materials in the polymer particles of (d) using a mineral acid. In one embodiment of the invention, the γ-irradiation is carried out as a function of methyl methacrylate (functional monomer) concentration. In another embodiment of the invention, the photochemical polymerization is carried out as a function of time of UV irradiation. In another embodiment of the invention, the thermal polymerization is carried out as a function of ethyleneglycoldimethacrylate (crosslinking monomer) concentration. In another embodiment of the invention, the functional monomer is selected from the group consisting of 4-vinylpyridine and methylmethacrylate. In another embodiment of the invention, the crosslinking monomer comprises ethylene glycol dimethacrylate. In another embodiment of the invention, the reaction is carried out using 2,2′-azobisisobutyronitrile is used as initiator in step (c). In yet another embodiment of the invention, the grinding and sieving in step (d) is carried out after drying of the erbium ion imprinted polymer materials. In another embodiment of the invention, the mineral acid used for leaching comprises HCl. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS In the drawings accompanying this specification, FIG. 1. Represents the UV-visible absorption spectra of 5,7-dichloroquinoline-8-ol (DCQ), 4-vinyl pyridine (VP), DCQ+VP, Er3++DCQ+Er, Er3++VP and Er3++DCQ+VP. FIG. 2 is a schematic representation of formation of Ternary mixed ligand complex. FIG. 3 is a schematic representation of polymer imprinting process. FIG. 4 represents the effect of methyl methacrylate (A) (functional monomer) concentration on preconcentration of Er3+ using IIP particles synthesized by □-irradiation. FIG. 5 represents the effect of time of UV-irradiation on preconcentration of Er3+ using IIP particles synthesized by photochemical polymerization. FIG. 6 represents the effect of ethyleneglycoldimethacrylate (EGDMA) (crosslinking monomer) concentration on the preconcentration of Er3+ using IIP particles synthesized by thermal polymerization. DETAILED DESCRIPTION OF THE INVENTION The present invention offers methods for synthesizing selective erbium ion imprinted polymer particles having accessible and homogenous imprinted sites for solid phase extraction from dilute aqueous solutions. As used herein, the term “ion imprinting polymer (IIP)” refers to a material that has been polymerized around an imprint ion in such a way that when imprint ion is removed from the material, cavities or “imprinted sites” remain in the material that are complementary in shape and size of the imprint ion. On the addition of IIP material to dilute solutions containing imprint ion, the imprint sites selectively binds imprint ion. Such binding allows the use of above tailored material for enrichment/separation of imprint ion from other such ions which are similar to it. The salient features of the invention include the following. i) Synthesis of tailored IIP particles by thermal, photochemical and □-irradiated polymerization. ii) Pretreatment of the polymer to leach the imprint ion. iii) Enrichment from dilute aqueous solutions. i) Synthesis of Tailored Erbium IIP Materials. There are two main steps in the synthesis of tailored erbium IIP materials (I) formation of ternary mixed ligand complex with imprint ion (Erbium) and (ii) polymerization of ternary mixed ligand complex with MMA and EGDMA. The formation of ternary complex was carried out in 2-methoxy ethanol (porogen). Evidence for complex formation was monitored by recording UV-visible spectra. FIG. 1 shows the absorption spectra of 5,7-dichloroquinoline-8-ol (DCQ), 4-vinyl pyridine (VP), DCQ+VP, Er3++DCQ, Er3++VP and Er3++DCQ+VP. These spectra clearly indicate the formation of ternary complex in 2-methoxy ethanol solution (see FIG. 2). The ternary complex was imprinted on addition of functional (HA) and crosslinking (EGDMA) monomers. In case of thermal and photochemical polymerization only 2,2′-azobisisobutyronitrile is added as polymerization initiator. The resulting IIP materials were dried in an oven at 50° C. to obtain Erbium IIP materials. FIG. 3 shows the schematic representation of polymer imprinted process. These materials were ground and sieved to obtain erbium IIP particles. FIGS. 4, 5 & 6 show the effect of MMA concentration, time of UV irradiation and EGDMA concentration on enrichment of Er3+ using IIPs synthesized by □-irradiation, photochemical and thermal polymerization respectively. ii) Pretreatment of the IIP Materials to Leach the Imprint Ion The imprint ion, i.e. Er3+ was leached from the polymer by stirring with 5N HCl solution for 6 h. The resulting IIP particles were dried in an oven at 50° C. to obtain erbium IIP—SPE particles which can be used for selective enrichment of erbium ions from dilute aqueous solutions. iii) Enrichment of Er3+ from Dilute Aqueous Solutions The enrichment of erbium ion from dilute aqueous solutions using Erbium IIP particles were studied in detail. FIG. 4 shows the effect of methylmethacrylate (MMA) concentration on the percent enrichment of erbium ion using Er3+ IIPs polymerized by γ-irradiation. The effect of time of UV irradiation on the percent enrichment of erbium using IIP particles synthesized by photochemical polymerization is shown in FIG. 5. The influence of crosslinking monomer (EGDMA) concentration during the enrichment of erbium ion is shown in FIG. 6 using IIP particles synthesized by thermal polymerization. Accordingly, the present invention provides “Synthesis of tailored IIP-SPE particles for uptake of erbium ions and a process thereof” which comprises the following related processes. (i) Making IIP particles by γ-irradiation, photochemical and thermal polymerization (ii) Enrichment of erbium ions from dilute aqueous solutions (iii) Separation of erbium from other lanthanides The following examples illustrate the synthesis of ion imprinted polymer materials for selective solid phase extraction of erbium ions. EXAMPLE 1 Polymerization by γ-Irradiation 1.0 mM of erbium chloride (0.44 g), 3.0 mM of DCQ (0.64 g) and 2 mM of VP (0.21 g) were taken in 50 ml R.B. flask and solubilized in 5 or 10 ml of 2-methoxy ethanol by stirring. 4 (0.4 g) or 8 (0.8 g) and 12 (1.2 g) mM of MMA and 16 (3.17 g) or 32 (6.34 g) and 48 (9.52 g) mM of EGDMA were added and stirred until a homogeneous solution is obtained. The monomer mixtures were transferred into test tubes, cooled to 0° C., purged with N2 for 10 min and sealed. These solutions were subjected to γ-irradiation of 1 M rad using Co60 source for 4 h. The solid formed was washed with water and dried in an oven at 50° C. This resulted in 5.70, 9.43 and 14.27 g of polymer material with 4, 8 and 12 mM of functional monomer respectively. The polymer embeded erbium ion was leached with 50% (v/v) HCl while stirring for 6 h. This resulted in 4.14, 7.52 and 11.29 g of polymer material with 4, 8 and 12 mM of functional monomer respectively after drying in an oven at 50° C. EXAMPLE 2 Polymerization by Photochemical Means 1.0 mM of erbium chloride (0.44 g), 3.0 mM of DCQ (0.64 g) and 2.0 mM of VP (0.21 g) were taken in 50 ml R.B. flask and solubilized in 10 ml of 2-methoxyethanol by stirring. 8 mM of MMA (0.8 g), 32 mM of EGDMA (6.35 g) and 50 mg of AIBN were added and stirred until a homogenous solution is obtained. The monomer mixtures are then transferred into test tubes, cooled to 0° C., purged with N2 for 10 min and sealed. These solutions were polymerized by subjecting to UV irradiation (300 nm) for 4, 8 and 16 h. The solid formed was washed with water and dried in an oven at 50° C. This resulted in 7.55, 9.85 and 9.95 g of polymer material with 4, 8 and 16 h of UV irradiation (300 nm). The polymer embeded erbium ion was leached 50% (v/v) HCl while stirring for 6 h. This resulted in 5.35, 7.31 and 7.36 g of polymer material with 4, 8 and 16 h of UV irradiation respectively after drying in an oven at 50° C. EXAMPLE 3 Polymerization by Thermal Means 1.0 mM of erbium chloride (0.44 g), 3.0 mM of DCQ (0.64 g) and 2.0 mM of VP (0.21 g) were taken in 50 ml R.B. flask and solubilized in 10 ml of 2-methoxyethanol by stirring. 8.0 mM of MMA (0.8 g); and 8, 16 and 32 mM EGDMA (1.59, 3.17 and 6.34 g) and 50 mg of is AIBN were added and stirred until a homogenous solution is obtained. The polymerization mixtures were cooled to 0° C., purged with N2 for 10 min, sealed and heated in an oil bath at ˜80° C. with stirring for 2 h. The solid formed was washed with water and dried in an oven at 50° C. This resulted in 4.32, 5.50 and 8.84 g of polymer material with 50, 66 and 80% of crosslinking monomer. The polymer embeded erbium ion was leached with 100 ml of 50% (v/v) HCl while stirring for 6 h, filtered and dried in an oven at 50° C. This resulted in 2.59, 3.90 and 7.90 g of erbium ion imprinted polymer materials. Advantages of the Present Invention Liquid-Liquid extraction process is replacing conventional ion exchange processes as the former one is rapid reliable and easy to scale up. How ever, liquid-liquid extraction processes requires 40-50 stages of counter current extraction as the separation factors for Er with respect to Y is closer to 1.0. Moreover, the use of large volumes of toxic chemicals viz. solvents & extractants are mandatory. On the other hand, the separations based on join imprinted polymer particles described in the present invention are environmentally friendlier, involves reduced costs due to lower consumption of chemicals and offer better selectivity coefficients for Er over Y, Dy, Gd, Tb etc. REFERENCES Patent Documents WO9807671 Mark et al Separating enatiomers by molecular imprinting U.S. Pat. No. 6,316,235 Mosbach et al preparation and use of magnetically susceptible polymer particles U.S. Pat. No. 5,786,428 Arnold et al Adsorbents for amino acids and peptide separation U.S. Pat. No. 5,461,175 Fischer et al Method for separating enantiomers of aryloxipropanolamine derivatives and chiral solid phase chromatography material for use in the method U.S. Pat. No. 6,063,637 Arnold et al Sensors for sugars and other metal binding analytes U.S. Pat. No. 5,587,273 Yan et al Molecularly imprinted materials, method for their preparation and devices employing such materials U.S. Pat. No. 6,310,110 Markowitz et al Molecularly imprinted material made by template directed synthesis U.S. Pat. No. 6,057,377 Sasaki et al Molecular receptors in metal oxide sol-gel materials U.S. Pat. No. 6,255,461 Mosbach et al Artificial antibodies to corticosteroids prepared by molecular imprinting US 2003 049870 Magnus et al Selective affinity material, preparation there of by molecular imprinting, and use of the same. US 2003 113234 Murray Polymer based permeable membrane for removal of ions US 2003 059346 Murray Method and apparatus for environmental phosphate/nitrate pollution removal using a selectively permeable molecularly imprinted polymer membrane U.S. Pat. No. 6,248,842 Singh et al Synthetic polymer matrices including pre-organised chelation sites for the selective and reversible binding of metals. WO9915,707 John et al Detection and extraction of an ion in a solution, particularly uranium ion. U.S. Pat. No. 6,251,280 Dai et al Imprint coating synthesis of selective functionalized ordered mesoporous sorbents for separation and sensors Non-Patent References Garcia et al, Tetrahedron Lett., 39 (1998) 8651. Ionic imprinting effect in gadolinium/lanthanum separation Vigneau et al, Anal. Chim. Acta, 435 (2001) 75. Ionic imprinted resins based on EDTA and DTPA derivatives for lanthanides (III) separation Vigneau et al, Chem. Lett. (2002) 202. Solid-Liquid separation of lanthanide/lanthanide and lanthanide/actinide using ionic imprinted polymer based on a DTPA derivative Biju et al, Anal. Chim. Acta, 478 (2003) 43. Ion imprinted polymer particles: synthesis. Characterization and dysprosium ion uptake properties suitable for analytical applications. Biju et al, Talanta, 60 (2003) 747. Effect of γ-irradiation of ion imprinted polymer (IIP) particles for preconcentrative separation of dysprosium from other selected lanthanides. | <SOH> BACKGROUND OF THE INVENTION <EOH>Monazite sand is processed by a series of beneficiation processes to produce lighter, middle and heavier rare earth chloride fractions. The last fraction contains 55-60% Y 2 O 3 along with Dy, Gd and Er as impurities. The preparation of 99.9-99.999% Y 2 O 3 gains importance as it is widely used in manufacture of lasers, superconducting materials and colour T.V. Phosphors. Hence, the separation of Dy, Gd and Er is an essential prerequisite to prepare such high purity Y 2 O 3 . The three different polymerization processes described in this patent enables the separation of erbium from Y 2 O 3 . Enantiomer Separation Reference is made to Mark et al., WO 98/07671; 1998, who have prepared imprinted polymers for the separation of optically active compounds of ibuprofen, naproxen and ketoprofen into their respective enantiomers. Reference is made to Mosbach et al., U.S. Pat. No. 6,316,235; 2001 who have prepared magnetically susceptible components by copolymerizing one or more functional monomers and crosslinking monomer in presence of at least one imprint molecule and at least one magnetically susceptible component such as iron oxide or nickel oxide. The imprint molecule was subsequently removed to form molecular memory recognition sites. These particles are used for selective separation of two different enantiomeric forms. Reference is also made to Arnold et al., U.S. Pat. No. 5,786,427; 1998, who prepared solid phase extractant materials which include polymeric matrix containing one or more metallic complexes by molecular imprinting, which selectively binds only one enantiomer of the optically active amino acid or peptide. Reference is made to Fischer et al, U.S. Pat. No. 5,461,175; 1995 who synthesized chiral chromatographic materials for separating enantiomers of a derivative of an aryloxipropanol amine. Sensors Reference is made to Arnold et al., U.S. Pat. No. 6,063,637; 2000 who have developed sensors composed of a metal complex that binds the target molecule and releases a proton or includes an exchangeable ligand which is exchanged for the target molecule during the binding interaction between the metal complex and target molecule. These sensors are meant for detecting the presence of sugars and other metal binding analytes. Reference is made to Yan et al., U.S. Pat. No. 5,587,273; 1996 who prepared molecular imprinted substrate and sensors by first forming a solution comprising a solvent and (a) polymeric material capable of undergoing an addition reaction with nitrene, (b) a cross-linking agent, (c) a functional monomer and (d) an imprinting molecule. Other Applications of Molecular Imprinting Reference is made to Markowitz et al, U.S. Pat. No. 6,310,110; 2001 who synthesized molecular imprinted porous structures by self assembling surfactant analogue to create at least one supramolecular structure having exposed imprint groups. The imprinted porous structure is formed by adding reactive monomers to the mixture and allowing the monomers to polymerize with the supramolecular structure serving as the template. Reference is also made to Sasaki et al., U.S. Pat. No. 6,057,377; 2000 who have developed a method for molecular imprinting on the surface of a sol-gel material, solvent, an imprinting molecule to form the molecular imprinted metal oxide sol-gel materials. Reference is made to Mosbach and Olof, U.S. Pat. No. 6,255,461; 2003 who prepared artificial antibodies by molecular imprinting, wherein methacrylic acid, ethylene glycoldimethacrylate and a corticosteroid print molecule are combined to form artificial antibody. These antibodies can be used in separation and analytical procedures. Reference is also made to Magnus et al., U.S. patent application 2003-049970; 2003 who have prepared selective adsorption material which can be used for purification or analysis of biological macromolecules. Ion Imprinting—Anions Reference is made to Murray, U.S. patent application 2003-113234; 2003 who has prepared molecularly imprinted polymer membranes for selectively collecting phosphate, nitrate and ferric ions. These membranes are prepared by copolymerizing a matrix monomer, cross linking monomer, ion imprinting complex, permeability agent and polymerization initiator, after which the ions of the ion imprinting complex and permeability agent are removed. The permeability agent creates channels in the membrane permitting membrane to communicate with the exterior surface of the the ion binding sites in the membrane. Murray, U.S. patent application 2003-059346; 2003 addresses the removal of phosphate/nitrate anions using selectively permeable polymer membrane. The selective binding site is prepared by ferric ion imprinting. Permeability is improved by using a polyester that associates with metal ions; the polyester is removed from the membrane by the same acid treatment used to remove ferric ion. The polyester creates channels directing the ion migration to the imprinted sites, thus, increasing the flux but maintaining selectivity. Ion Imprinting—Cations Reference is made to Singh et al, U.S. Pat. No. 6,248,842; 2001 who produced selective, crosslinked chelating polymers by substituting an acyclic chelating agent with a polymerizable functional group. The resulting substituted acyclic chelating agent is then complexed with the target metal ion, i.e. copper. A crosslinkable monomer is then added and the complexed material is crosslinked. The complexed metal is then removed, providing a crosslinked polymeric chelating agent that has been templated for the target metal ion. Reference is made to John et al, WO 99/15707; 1999 relating to the detection and extraction of uranyl ion by polymer imprinting wherein the complexable functionality is of the formula CTCOOH, where T is a hydrogen or any halogen (preferably chlorine), methyl and halogen substituted form thereof or COOH or PhCOOH. Gladis and Rao also teach synthesis of ion imprinted polymers for solid phase extractive preconcentration/separation of uranyl ion from host of tetravalent, tervalent and bivalent inorganic ions from both aqueous and synthetic sea water solutions. They form ternary mixed ligand complex of imprint ion with quinoline-8-ol or its dihalo derivatives and 4-vinyl pyridine in presence of styrene and divinyl benzene as functional and crosslinking monomers. Reference is made to Dai et al, U.S. Pat. No. 6,251,280; 2001 who prepared mesophorous sorbent materials by ion imprinting technique for the separation of inorganics using bifunctional ligands such as amines, thiols, carboxylic acids, sulphonic acids and phosphonic acids. Carboxylic acid groups on bifunctional ligands are used during the formation of mesophoric sorbent materials specific for erbium template ion. Rao et al [Trends in Anal. Chem.; 2003] have reviewed the preparation of tailored materials for preconcentration/separation of metals by ion imprinted polymers for solid phase extraction (IIP-SPE). Ion imprinted polymer (IIP) materials with nanopores were prepared by formation of ternary complex of palladium imprint ion with dimethyl glyoxime and 4-vinyl pyridine and thermally copolymerizing with styrene and divinyl benzene in presence of 2,2′-azobisisobutyronitrile using cyclohexanol as porogen [Sobhi et al, Anal. Chim. Acta, 488 (2003) 173-182]. Cation imprinted SPE materials for separation of La and Gd based on diethylenetriaminepentaacetic acid (DTPA) derivatives have been prepared. Imprinting effect was observed with materials prepared in the presence of Gd salts and exhibited high efficiency and selectivity than the corresponding blank polymers [Garcia et al, Tetrahedran Lett:, 39 (1998) 8651]. The functionalized monomer of DTPA was copolymerized with commercially available divinyl benzene (DVB) containing 45% ethyl styrene in presence of Gd 3+ salt. The resulting IIP was found to be more selective for Gd compared to La [Vigneau et al, Anal. Chim. Acta, 435 (2001) 75]. These selective studies were extended to determine S Gd/Eu and S Gd/Lu using Gd imprinted IIP [Logneau et al, Chem. Lett. (2002) 202]. Biju et al [Anal. Chim. Acta, 478 (2003) 43-51] have synthesized Dy(III) IIP particles by copolymerizing styrene (functional monomer) in presence of DVB as crosslinking monomer. Some authors [Talanta, 60 (2003) 747-754] have reported improved selectivity coefficients for Dy over La, Nd, Y and Lu on post γ-irradiation of Dy IIP particles. Molecular imprinted polymer particles prepared are widely used in separation of enantiomers, structurally related drugs, amino acid derivatives, nucleotide base derivatives etc. Thus, they find widespread use in chemical and pharmaceutical industries, water purification and waste treatment. On the other hand, the preparation of ion imprinted polymer particles are not that popular for the separation of closely related inorganic ions. The patent by Dai et al [U.S. Pat. No. 6,251,280; 2001] alone addresses this problem but is too general and do not involve separation of Er from closely related lanthanides. | <SOH> SUMMARY OF THE INVENTION <EOH>Accordingly the present invention provides a process for the synthesis of ion imprinted polymer particles for solid phase extraction preconcentration of erbium ions which comprises: (a) forming a mixed ligand ternary complex of erbium imprint ion with 5,7-dichloroquinoline-8-ol and 4-vinyl pyridine; (b) dissolving the ternary complex in a suitable porogen to form a pre-polymerizing mixture; (c) combining the mixture of step (b) with a functional monomer and a crosslinking monomer and polymerizing by γ-irradiation or by photochemical and thermal polymerization to obtain a polymer material; (d) grinding and sieving of polymer material obtained in (c) to prepare erbium ion imprinted polymer particles; (e) selective leaching of imprint ion embedded materials in the polymer particles of (d) using a mineral acid. In one embodiment of the invention, the γ-irradiation is carried out as a function of methyl methacrylate (functional monomer) concentration. In another embodiment of the invention, the photochemical polymerization is carried out as a function of time of UV irradiation. In another embodiment of the invention, the thermal polymerization is carried out as a function of ethyleneglycoldimethacrylate (crosslinking monomer) concentration. In another embodiment of the invention, the functional monomer is selected from the group consisting of 4-vinylpyridine and methylmethacrylate. In another embodiment of the invention, the crosslinking monomer comprises ethylene glycol dimethacrylate. In another embodiment of the invention, the reaction is carried out using 2,2′-azobisisobutyronitrile is used as initiator in step (c). In yet another embodiment of the invention, the grinding and sieving in step (d) is carried out after drying of the erbium ion imprinted polymer materials. In another embodiment of the invention, the mineral acid used for leaching comprises HCl. | 20040326 | 20051101 | 20050929 | 97379.0 | 0 | BOYKIN, TERRESSA M | SYNTHESIS OF ION IMPRINTED POLYMER PARTICLES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,811,419 | ACCEPTED | METHOD AND APPARATUS FOR POSITIONING A SLEEVE DOWN HOLE IN A HYDROCARBON PRODUCING WELL AND PIPELINES | A method for positioning sleeve down hole in a hydrocarbon producing well. A running assembly with associated sleeve is run down a hydrocarbon producing well until the sleeve is in a desired positioned in a conduit. The sleeve is expanded until it sealingly engages the conduit. Pressure is maintained within the sleeve until the seals of holding the pressure sequentially fail to expand the ends of the sleeve. When a preset pressure threshold is reached, the pressure is relieved. The running assembly is then pulled back through the expanded sleeve to surface. A major advantage of this method is that the expanded sleeve provides sufficient internal clearance that a further sleeve of the same size as the original may, in future, be passed through the expanded sleeve and positioned lower down in the well. | 1. An assembly for positioning a sleeve down hole in a hydrocarbon producing well, comprising: a sleeve having an interior surface, an exterior surface, a first end, a second end, and seals on the exterior surface of the sleeve, the sleeve being made of a material which is capable of expanding radially when pressure is applied to the interior surface; a running tool support rod extending axially through the sleeve, the support rod having a first end, a second end, an exterior surface; a first seal assembly positioned at the first end of the sleeve, the first seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a second seal assembly positioned at the second end of the sleeve, the second seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a first centralizer positioned at the first end of the sleeve, adapted to centralize the first end of the sleeve; a second centralizer positioned at the second end of the sleeve, adapted to centralize the second end of the sleeve; means for preventing an outermost seal of the second seal assembly from exiting the sleeve until the sleeve has been fully expanded and a preset pressure threshold has been reached; a fluid conduit extending through the support rod to a fluid feed inlet positioned between the first seal assembly and the second seal assembly; and means for selectively sending fluid through the fluid conduit to expand the sleeve by remote activation. 2. The assembly as defined in claim 1, wherein the first centralizer and the second centralizer have circumferentially spaced rollers. 3. The assembly as defined in claim 1, wherein the means for preventing the outermost seal of the second seal assembly from exiting the sleeve until the sleeve has been fully expanded and a preset pressure threshold has been reached is a shear sleeve secured to the support rod by shear screws adapted to shear when the preset pressure threshold is reached. 4. The assembly as defined in claim 1, wherein the means for selectively expanding the sleeve includes means for generating pressure by expansion of gases. 5. The assembly as defined in claim 4, wherein a combustion chamber is provided for the combustion of a gas generating medium, whereby pressure is generated by expansion of gases. 6. The assembly as defined in claim 1, wherein the means for selectively expanding the sleeve includes filling the sleeve with a liquid, and having a fluid chamber filled with liquid in fluid communication with the sleeve, the fluid chamber having a first end and a second end, a piston is provided which has a first face and a second face, the piston being positioned at the first end of the fluid chamber remote from the sleeve, the piston being axially movable in the fluid chamber when a force acts upon the first face of the piston, as the piston moves toward the second end of the fluid chamber the second face of the piston exerts a hydraulic force upon liquid to expand the sleeve. 7. The assembly as defined in claim 6, a restriction being positioned at the second end of the fluid chamber, the movement of the piston being hydraulically slowed as the piston enters the restriction, thereby preventing the first seal assembly being exposed to impact damage from the piston. 8. The assembly as defined in claim 6, wherein an expansion chamber is provided to accommodate rapidly expanding gases and the first face of the piston is exposed to rapidly expanding gases in the expansion chamber, the rapidly expanding gases serving as a motive force to move the piston toward the second end of the fluid chamber. 9. The assembly as defined in claim 5, wherein an electric igniter element is provided in the combustion chamber and an electrical conduit extends from surface to facilitate remotely igniting the gas generating medium by sending an electrical current from surface to the electric igniter element. 10. The assembly as defined in claim 8, wherein a bleed valve is provided to relieve pressure within the expansion chamber. 11. The assembly as defined in claim 1, wherein the first seal assembly and the second seal assembly include at least one inner resilient seal axially spaced from at least one outer high pressure seal. 12. The assembly as defined in claim 1, wherein a stopper nut is positioned on a lower remote end of the support rod below the shear sleeve. 13. The assembly as defined in claim 11, wherein the at least one outer high pressure seal is carried by at least one seal carrier sleeve. 14. The assembly as defined in claim 1, wherein stabilizing slips are provided, the slips being forced outwardly to secure the running tool in the well bore by hydraulic pressure within the fluid chamber. 15. The assembly as defined in claim 1, wherein the first seal assembly includes an expandable annular primary seal and an annular primary seal activation member having a primary face with an inclined plane profile, an increase in internal pressure upon activation of the assembly directing the primary seal up the inclined plane profile of the primary seal activation member, the primary seal expanding in circumference as it climbs the inclined plane profile and comes into sealing engagement with the sleeve. 16. The assembly as defined in claim 15, wherein the primary seal activation member has a secondary face which is opposed to the primary face, the secondary face also having an inclined plane profile, the primary seal activation member being axially movable along the support rod in response to increases in internal pressure upon activation of the assembly, an annular secondary seal activation member being provided having an inclined plane profile, the secondary seal activation member being fixed in position to the support rod, a secondary seal being positioned between the primary seal activation member and the secondary seal activation member, the secondary seal having a plurality of sealing segments arranged around the circumference of the support rod, each of the sealing segments having an outwardly angled first end and an outwardly angled second end, upon movement of the primary seal activation member along the support rod toward the secondary seal activation member, the secondary seal being sandwiched between the primary seal activation member and the secondary seal activation member with the sealing segments being forced outwardly as the outwardly angled first end is forced up the inclined plane profile on the secondary face of the primary seal activation member and of the outwardly angled second end is forced up the inclined plane profile of the secondary seal activation member, means being provided to urge the sealing segments of the secondary seal back into engagement with the support rod. 17. The seal assembly as defined in claim 16, wherein an expandable resilient band encircles the sealing segments of the secondary seal and pulls the sealing segments back into engagement with the support rod. 18. The seal assembly as defined in claim 16, wherein springs are positioned on an exterior surface of each of the sealing elements around the circumference of the secondary seal, the springs pushing the sealing segments of the secondary seal back into engagement with the support rod. 19. An assembly for positioning a sleeve down hole in a hydrocarbon producing well, comprising: a sleeve having an interior surface, an exterior surface, a first end and a second end, and seals on the exterior surface of the sleeve, the sleeve being made of a material which is capable of expanding radially when pressure is applied to the interior surface; a running tool including a running tool support rod extending axially through the sleeve, the support rod having a first end, a second end, and an exterior surface; a first seal assembly positioned at the first end of the sleeve, the first seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a second seal assembly positioned at the second end of the sleeve, the second seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a first centralizer positioned at the first end of the sleeve, adapted to centralize the first end of the sleeve; a second centralizer positioned at the second end of the sleeve, adapted to centralize the second end of the sleeve; a shear sleeve is secured to the support rod by shear screws, preventing an outermost seal of the second seal assembly from exiting the sleeve until the sleeve has been fully expanded, the shear screws being adapted to shear when a preset pressure threshold is reached; a combustion chamber for the combustion of a gas generating medium; an electric igniter element in the combustion chamber and an electrical conduit extends from surface to facilitate remotely igniting the gas generating medium by sending an electrical current from surface to the electric igniter element; an expansion chamber is provided adjacent to the combustion chamber, to accommodate rapidly expanding gases generated by the combustion of the gas generating medium in the combustion chamber; a fluid chamber filled with liquid in fluid communication with the sleeve which is also filled with liquid, the fluid chamber having a first end and a second end; a fluid conduit extending axially through the support rod from the second end of the fluid chamber to a feed inlet positioned between the first seal assembly and the second seal assembly; a piston having a first face and a second face, the piston being positioned at the first end of the fluid chamber remote from the sleeve, the piston being axially movable in the fluid chamber when a force acts upon the first face of the piston, the first face of the piston being exposed to rapidly expanding gases in the expansion chamber, the rapidly expanding gases serving as a motive force to move the piston toward the second end of the fluid chamber, thereby exerting a hydraulic force upon liquid to expand the sleeve. 20. The assembly as defined in claim 19, a restriction being positioned at the second end of the fluid chamber, the movement of the piston being hydraulically slowed as the piston enters the restriction, thereby preventing the first seal assembly being exposed to impact damage from the piston. 21. The assembly as defined in claim 19, wherein the first centralizer and the second centralizer have circumferentially spaced rollers. 22. The assembly as defined in claim 19, wherein a bleed valve is provided to relieve pressure exerted within the expansion chamber. 23. The assembly as defined in claim 19, wherein the first seal assembly and the second seal assembly include at least one inner resilient seal axially spaced from at least one outer high pressure seal. 24. The assembly as defined in claim 19, wherein a stopper nut is positioned on a lower remote end of the support rod below the shear sleeve. 25. The assembly as defined in claim 23, wherein the at least one outer high pressure seal is carried by at least one seal carrier sleeve. 26. The assembly as defined in claim 19, wherein stabilizing slips are provided, the slips being forced outwardly to secure the running tool in the well bore by hydraulic pressure within the fluid chamber, during the setting operation, the slips releasing and disengaging when pressure is relieved upon the shear screws failing. 27. The assembly as defined in claim 19, wherein circumferential seals are provided on the exterior surface of the sleeve. 28. A method for positioning sleeve down hole in a hydrocarbon producing well, comprising the steps of: running a running assembly with associated sleeve down a hydrocarbon producing well until the sleeve is in a desired positioned in a conduit, the running assembly including a first seal assembly sealing a first end of the sleeve and a second seal assembly sealing a second end of the sleeve, the first seal assembly and the second seal assembly having seals adapted to sequentially fail to expand the first end and the second end of the sleeve and to permit the second seal assembly to exit the second end of the sleeve and release the pressure when a preset threshold is reached; expanding the sleeve until the sleeve sealingly engages the conduit; maintaining pressure within the sleeve as the seals of the first seal assembly and the second seal assembly sequentially fail to expand the first end and the second end of the sleeve and until the preset threshold is reached, at which threshold pressure the second seal assembly exits the second end of the sleeve to relieve the pressure; and pulling the running assembly back through the expanded sleeve to surface, the expanded sleeve providing sufficient internal clearance that a further sleeve of the same size as the original may, in future, be passed through the expanded sleeve and positioned lower down in the well. 29. A method for positioning sleeve down hole in a hydrocarbon producing well, comprising the steps of: providing a running assembly which includes: a sleeve having an interior surface, an exterior surface, a first end and a second end, and seals on the exterior surface of the sleeve, the sleeve being made of a material which is capable of expanding radially when pressure is applied to the interior surface; a running tool support rod extending axially through the sleeve, the support rod having a first end, a second end, and an exterior surface; a first seal assembly positioned at the first end of the sleeve, the first seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a second seal assembly positioned at the second end of the sleeve, the second seal assembly having more than one annular seal, each annular seal engaging the exterior surface of the support rod and the interior surface of sleeve; a first centralizer positioned at the first end of the sleeve, adapted to centralize the first end of the sleeve; a second centralizer positioned at the second end of the sleeve, adapted to centralize the second end of the sleeve; means for preventing outermost seals of the more than one seals of each of the first seal assembly and the second seal assembly from exiting the sleeve until the sleeve has been fully expanded and a preset pressure threshold has been reached; a fluid conduit extending through the support rod to a fluid feed inlet positioned between the first seal assembly and the second seal assembly; and means for selectively sending fluid through the fluid conduit to expand the sleeve by remote activation. running the assembly down a hydrocarbon producing well until the sleeve is positioned within a conduit; expanding the sleeve until the sleeve sealingly engages the conduit; maintaining pressure within the sleeve as the seals of the first seal assembly and the second seal assembly sequentially fail to expand the first end and the second end of the sleeve and until a preset threshold is reached, at which threshold pressure the second seal assembly exits the second end of the sleeve; pulling the support rod back through the expanded sleeve and back to surface, the expanded sleeve providing sufficient internal clearance that a further sleeve of the same size as the original may in future be passed through the expanded sleeve and positioned lower down in the well. 30. The method as defined in claim 29, a shear sleeve being secured to the support rod by shear screws to prevent an outermost seal of the more than one seals of the second seal assembly from exiting the sleeve until the sleeve has been fully expanded, the shear screws being adapted to shear when a preset pressure threshold is reached. 31. The method as defined in claim 29, a combustion chamber being provided for the combustion of a gas generating medium; an electric igniter element being provided in the combustion chamber and an electrical conduit extending from surface to facilitate remotely igniting the gas generating medium by sending an electrical current from surface to the electric igniter element; an expansion chamber being provided adjacent to the combustion chamber, to accommodate rapidly expanding gases generated by the combustion of the gas generating medium in the combustion chamber; a fluid chamber filled with liquid being in fluid communication with the sleeve which is also filled with liquid, the fluid chamber having a first end and a second end; a fluid conduit extending axially through the support rod from the second end of the fluid chamber to a feed inlet positioned between the first seal assembly and the second seal assembly; a piston having a first face and a second face, the piston being positioned at the first end of the fluid chamber remote from the sleeve, the piston being axially movable in the fluid chamber when a force acts upon the first face of the piston, the first face of the piston being exposed to rapidly expanding gases in the expansion chamber, the rapidly expanding gases serving as a motive force to move the piston toward the second end of the fluid chamber, thereby exerting a hydraulic force upon liquid to expand the sleeve. | FIELD OF THE INVENTION The present invention relates to positioning sleeves in a hydrocarbon producing well and, in particular, sleeves used to seal perforations to prevent the entry into the well of unwanted fluids and sleeves used to repair pipelines. BACKGROUND OF THE INVENTION The systems currently used to seal perforations have a fundamental flaw. They form a restriction in the well. This creates a problem should there later arise a need to seal other perforations further down in the well. U.S. Pat. No. 4,069,573 (Rogers 1978) (reissued as RE30,802 in 1981) discloses an invention entitled a “method of securing a sleeve within a tube”. This type of sleeve was developed to repair heat exchangers associated with nuclear power generation plants. The sleeves are positioned within the tube, and then expanded outwardly to engage the tube. In accordance with the teachings of the Rogers patent, the sleeves are expanded using hydraulics or by applying a compressive force to an elastomer material. U.S. Pat. No. 4,793,382 (Szalvay 1988) discloses an assembly for repairing a damaged pipe. The Szalvay reference contains a discussion of the shortcomings of the prior art apparatus used to expand sleeves. Some of such apparatus leave components in the damaged pipe, thereby restricting subsequent fluid flow. Others of such apparatus must be repositioned and then re-expanded at intervals along the sleeve. The Rogers reference is criticized as not being suitable where a leak proof fit is necessary; as is the teaching of the Rogers reference of using the sleeve to expand the damaged pipe. The Szalvay reference addresses these shortcomings by advocating the use of shape memory alloy elements. None of the prior art references address how a sleeve might be installed at a distance of several miles down a hydrocarbon producing well to seal off perforated zones or possibly repair damaged sections of conduit. SUMMARY OF THE INVENTION What is required is a method and apparatus for positioning sleeves down hole in a hydrocarbon producing well. According to one aspect of the present invention there is provided a method for positioning sleeve down hole in a hydrocarbon producing well. A first step involves running a running assembly with associated sleeve down a hydrocarbon producing well until the sleeve is in a desired positioned in a conduit. The running assembly includes a first seal assembly sealing a first end of the sleeve and a second seal assembly sealing a second end of the sleeve. The first seal assembly and the second seal assembly have seals adapted to sequentially fail to expand the first end and the second end of the sleeve and to permit the second seal assembly to exit the second end of the sleeve and release the pressure when a preset threshold is reached. A second step involves expanding the sleeve until the sleeve sealingly engages the conduit. A third step involves maintaining pressure within the sleeve as the seals of the first seal assembly and the second seal assembly sequentially fail to expand the first end and the second end of the sleeve and until the preset threshold is reached, at which threshold pressure the second seal assembly exits the second end of the sleeve to relieve the pressure. A fourth step involves pulling the running assembly back through the expanded sleeve to surface. The expanded sleeve providing sufficient internal clearance that a further sleeve of the same size as the original may, in future, be passed through the expanded sleeve and positioned lower down in the well. According to another aspect of the present invention there is provided an assembly for positioning a sleeve down hole in a hydrocarbon producing well. A sleeve is provided having an interior surface, an exterior surface, a first end and a second end. The sleeve is made of a material which is capable of expanding radially when pressure is applied to the interior surface. A running tool support rod extends axially through the sleeve. The support rod has a first end, a second end, and an exterior surface. A first seal assembly is positioned at the first end of the sleeve. The first seal assembly has more than one annular seal. Each annular seal engages the exterior surface of the support rod and the interior surface of sleeve. A second seal assembly is positioned at the second end of the sleeve. The second seal assembly has more than one annular seal. Each annular seal engages the exterior surface of the support rod and the interior surface of sleeve. A first centralizer is positioned at the first end of the sleeve and is adapted to centralize the first end of the sleeve. A second centralizer is positioned at the second end of the sleeve and is adapted to centralize the second end of the sleeve. Means are provided for preventing outermost seals of the more than one seals of each of the first seal assembly and the second seal assembly from exiting the sleeve until the sleeve has been fully expanded and a preset pressure threshold has been reached. Means are provided for selectively expanding the sleeve by remote activation from surface. The method and apparatus, as outlined above and hereinafter further described, represents a significant advance in the art. It seals perforations with negligible restriction, so that it is possible to subsequently pass equipment through and seal perforations lower down in the well. As will hereinafter be further described, the preferred means for maintaining the outermost seal of the second seal assembly in position until the sleeve is fully expanded is to secure a shear sleeve to the support rod by shear screws. The shear sleeve provides containment to prevent an outermost seal of the second seal assembly from exiting the sleeve and relieving the pressure until the sleeve has been fully expanded. The shear screws are adapted to shear when a preset pressure threshold is reached. As will hereinafter be further described, the preferred mean for expanding the sleeve is to provide a combustion chamber for the combustion of a gas generating medium. An electric igniter element is provided in the combustion chamber and an electrical conduit extends from surface to facilitate remotely igniting the gas generating medium by sending an electrical current from surface to the electric igniter element. An expansion chamber is provided adjacent to the combustion chamber, to accommodate rapidly expanding gases generated by the combustion of the gas generating medium in the combustion chamber. Although the sleeve could be expanded using only gases, the combustion of gas generating medium tends to leave a residue. It is, therefore, preferred that a fluid chamber be provided which is filled with liquid. The fluid chamber is in fluid communication with the sleeve, which is also filled with liquid. The fluid chamber has a first end and a second end. A fluid conduit extends axially through the support rod from the second end of the fluid chamber to a feed inlet positioned between the first seal assembly and the second seal assembly. A piston is provided having a first face and a second face. The piston is positioned at the first end of the fluid chamber remote from the sleeve. The piston is axially movable in the fluid chamber when a force acts upon the first face of the piston. The first face of the piston is exposed to rapidly expanding gases in the expansion chamber. The rapidly expanding gases serve as a motive force to move the piston toward the second end of the fluid chamber, thereby exerting a hydraulic force upon liquid to expand the sleeve. BRIEF DESCRIPTION OF THE DRAWINGS These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein: FIG. 1 is a side elevation view, in section of a first section of the assembly for positioning sleeves down hole according to the present invention. FIG. 2 is a side elevation view, in section, of a second section of the assembly for positioning sleeves down hole according to the present invention, located between the sections depicted in FIG. 1 and FIG. 3. FIG. 3 is a side elevation view, in section of a third section of the assembly for positioning sleeves down hole according to the present invention, located between the sections depicted in FIG. 2 and FIG. 4. FIG. 4 is a side elevation view, in section of a fourth section of the assembly for positioning sleeves down hole according to the present invention, located adjacent the section depicted in FIG. 3. FIG. 5 is a side elevation view, in section, of the assembly for positioning sleeves down hole before the sleeve is expanded. FIG. 6 is a side elevation view, in section, of the assembly for positioning sleeves down hole after the sleeve is expanded. FIG. 7 is a detailed side elevation view, in section, of an alternative sealing assembly for the assembly for positioning sleeves, the sealing system being shown in an unexpanded running position. FIG. 8 is an end elevation view, in section, of the alternative sealing assembly illustrated in FIG. 7. FIG. 9 is a detailed side elevation view, in section, of an alternative sealing assembly illustrated in FIG. 7, shown in an expanded position. FIG. 10 is an end elevation view, in section, of the alternative sealing assembly illustrated in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment, an assembly for positioning sleeves down hole generally identified by reference numeral 10, will now be described with reference to FIGS. 1 through 6. Structure and Relationship of Parts: Referring now to FIG. 1, there is shown the first section of an assembly 10 for positioning a sleeve down hole in a hydrocarbon producing well. Referring to FIG. 3, a third section of the assembly 10, a sleeve 11 has an interior surface 12, an exterior surface 14, a first end 16 and, in FIG. 4, a second end 18. The sleeve 11 is made of a material which is capable of expanding radially when pressure is applied to the interior surface 12. Referring to FIGS. 3 and 4, extending axially through the sleeve 11 is a running tool support rod 20. The support rod 20 has a first end 23, a second end 24, and an exterior surface. Referring to FIG. 2, the upper remote end 60 of the support rod 20 is securely mounted into the assembly via engagement with machine threads 61. Stabilizing slips 62 are provided, the purpose and function of which will hereinafter be further described. In addition, circumferential seals 70 are provided on the exterior surface 14 of the sleeve 11. There are seal assemblies at each end of the sleeve 11, such that, referring to FIG. 2, there is a first seal assembly 28 positioned at the first end 16 of the sleeve 11, and, referring to FIG. 4, there is a second seal assembly 30 positioned at the second end 18 of the sleeve 11. In FIG. 2, the first seal assembly 28 has more than one annular seal 32, where each annular seal 32 engages the exterior surface 26 of the support rod 20 and the interior surface 12 of sleeve 11. In FIG. 4, the second seal 30 assembly also has more than one annular seal 32, with each annular seal 32 engaging the exterior surface 26 of the support rod 20 and the interior surface 12 of sleeve 11. For a more controlled expansion of the sleeve 11, the seal assemblies 28 and 30 may include at least one inner resilient seal 52 axially spaced from at least one outer high pressure seal 54. The inner seal 52 is such that it will fail before the outer high pressure seal 54. The outer high pressure seals 54 are shown to be carried by seal carrier sleeves 64. Referring to FIG. 2, a first centralizer 34 positioned at the first end 16 of the sleeve 11, and referring to FIG. 4, a second centralizer 36 is positioned at the second end 18 of the sleeve 11, each adapted to centralize their respective ends of the sleeve 11. The centralizers shown have circumferentially spaced rollers 37. Rollers 37 serve to prevent damage to circumferential seals 70 on exterior surface 14 of sleeve 11, during the descent into the well. Rollers 37 also aid in preventing the assembly from getting stuck or hung up against restrictions in the well either during insertion or withdrawal. This is the case regardless of the deviation angle of the conduit, from vertical. Referring to FIG. 4, there is a shear sleeve 21 secured to the support rod 20 by shear screws 22 to prevent an outermost annular seal 54 of the second seal assembly 30 from exiting the sleeve 11 until the sleeve 11 has been fully expanded. Shear screws 22, are adapted to shear when a preset pressure threshold is reached. Second seal assembly 30 is then able to exit sleeve 11 to release the pressure. The preset pressure threshold is above that required to fully expand the sleeve 11. Below the shear sleeve 21, there is shown a stopper nut 56 positioned on a lower remote end 58 of the support rod 10. Stopper nut prevents shear sleeve 21 from being lost down the well. Referring to FIG. 1, there is also provided a combustion chamber 38 for the combustion of a gas generating medium 40 such as a slow burning powder that is placed within the combustion chamber 38, as well as an electric igniter element 42 in the combustion chamber 38. An electrical conduit 43 extends from surface 27 to facilitate remotely igniting the gas generating medium 40 by sending an electrical current from surface to the electric igniter element 42. Adjacent to the combustion chamber 38 is an expansion chamber 44 to accommodate rapidly expanding gases generated by the combustion of the gas generating medium 40 in the combustion chamber 38. Referring to FIG. 2, a fluid chamber 51 is provided which is filled with a liquid, such as a low viscosity hydraulic fluid. Fluid chamber 51 is in fluid communication with sleeve 11, which is filled with the same liquid. Fluid chamber 51 has a first end 53 and a second end 55. A fluid conduit 48 extends axially through support rod 20 from second end 55 of fluid chamber 51 to a feed inlet 46 positioned between first seal assembly 28 and second seal assembly 30 shown in FIG. 3. Referring to FIG. 2, a piston 57 is provided having a first face 59 and, in FIG. 3, a second face 61. Piston 57 is initially positioned at first end 53 of fluid chamber 51 remote from first seal assembly 28 of sleeve 11. However, piston 57 is axially movable in fluid chamber 51 when a force acts upon first face 59. First face 59 of piston 57 is exposed to rapidly expanding gases from expansion chamber 44. The rapidly expanding gases serve as a motive force to move piston 57 from its initial position at first end 53 toward second end 55 of fluid chamber 51. This exerts a hydraulic force upon liquid, which is transmitted through fluid conduit 48 and feed inlet 46 to expand sleeve 11. It will be appreciated that the force of the expanding gases is capable of propelling piston 57 with great force. A restriction 63 is, therefore, provided at second end 55 of fluid chamber 51. As piston 57 approaches second end 55, it encounters restriction 63. The movement of piston 57 is hydraulically slowed as piston 57 enters restriction 63. This prevents first seal assembly 28 from being subjected to impact damage from piston 57. Referring to FIG. 1, the expansion chamber 44 is provided with a bleed valve 50 that is used to relieve pressure residual pressure in expansion chamber 44 after the assembly has been removed from the well. It is to be noted that expansion chamber 44 is designed so the volume of burnt gases in expansion chamber 44 will be less than the volume of liquid in fluid chamber 51. This allows for a significant drop in gas pressure within expansion chamber 44 to occur, when hydraulic pressure is released from fluid chamber 51 immediately after operation of the assembly. As previously described, slips 62 are provided as shown in FIG. 2. Slips 62 are in communication with fluid chamber 51. Slips 62 are forced outwardly by hydraulic pressure within fluid chamber 51. Slips 62 engage the well bore to prevent any unwanted movement of the assembly during the setting operation which might result in improper positioning of sleeve 11. As slips 62 are deployed by pressure. They retract upon release of pressure within fluid chamber 51. Operation: Referring now to FIG. 5, there is a sleeve 11 positioned down hole in a hydrocarbon producing well 66. The running assembly 10 is generally similar to that which is described previously. The assembly 10 is run down the hydrocarbon producing well 66 until the sleeve 11 is positioned as desired within a conduit 68. Sleeve 11 may be positioned to block perforations, or it ma be positioned for another purpose. Once the sleeve 11 is positioned, the electric igniter element 42 ignites the gas generating medium 40 by sending an electrical current from the surface 27 through the electrical conduit 44. Rapidly expanding gases fill the expansion chamber 44 adjacent to the combustion chamber 38. First face 59 of piston 57 is exposed to rapidly expanding gases from expansion chamber 44. The rapidly expanding gases serve as a motive force to move piston 57 from its initial position at first end 53 toward second end 55 of fluid chamber 51. This exerts a hydraulic force upon liquid in fluid chamber 51, which is transmitted through fluid conduit 48 and feed inlet 46 to expand sleeve 11. Slips 62 are forced outwardly by hydraulic pressure within fluid chamber 51. Slips 62 engage the well bore to prevent any unwanted movement of the assembly during the setting operation. The sleeve 11 is expanded by hydraulic pressure until the sleeve 11 engages conduit 68. Pressure is then maintained within the sleeve 11 as the seals 32 of the first seal assembly 28 and the second seal assembly 30 sequentially fail. This expands first end 16 and second end 18 of sleeve 11. When a preset threshold is reached shear screws 22 shear. When shear screws 22 shear, shear sleeve 21 slides down support rod 20. Stopper nut 56 prevents shear sleeve from being lost down the well. Once shear sleeve 21 moves, second seal assembly 30 is free to exit second end 18 of sleeve 11, releasing the pressure and dumping the liquid down the well. The support rod 20 is then pulled through expanded sleeve 11 back to surface 27, as shown in FIG. 6. Expanded sleeve 11 provides sufficient internal clearance that a further sleeve of the same size as the original may, in future, be passed through the expanded sleeve and positioned lower down in the well. This is a significant advantage over other systems, which restrict future access. The assembly for positioning sleeves may be deployed by, for example, electric wireline, coiled tubing, slickline, tubing, or drill pipe. In addition, while the preferred embodiment has been described using a medium that generates gas under combustion, it will be understood that other methods of providing pressure exist, such as other gas generators, pressure from miniature down hole pumps, or pressure applied from pumps or other sources of pressure on surface down the coiled tubing, tubing or drill pipe. Variations: Assembly 10, as described above, was tested dozens of times and was able to successfully expand the sleeve every time. However, when applications were encountered requiring a sleeve made from a thicker gauge of metal, problems were encountered. The thicker gauge of metal required greater pressure to expand it. However, as pressures in excess of 5000 pounds per square inch were reached, seal failure was experienced prior to the shear screws shearing. It was determined that this could be addressed by having the outer diameter of the sealing system adjust as the sleeve expanded. With the original system illustrated and described above, the internal diameter changed, but the outer diameter did not. In order to make a full and complete disclosure, FIGS. 7 through 10 are included in this application which illustrate the seal modifications used to withstand the higher pressures needed to expand sleeves made from thicker gauge of metal. Thicker gauge metal is necessary in applications in which seal grooves are required to accommodate exterior “O” ring seals used to ensure proper exterior sealing of the sleeve. Referring now to FIG. 7, first seal assembly 28 includes an expandable annular primary seal 102 and an annular primary seal activation member 104. Activation member 104 has a primary face 106 with an inclined plane profile 108. Upon activation of assembly 10, an increase in internal pressure directs primary seal 102 up inclined plane profile 108 of primary seal activation member 104. Primary seal 102 expands in circumference as it climbs inclined plane profile 108 and comes into sealing engagement with sleeve 11, as shown in FIG. 9. Referring again to FIG. 7, primary seal activation member 104 has a secondary face 110 which is opposed to primary face 106. Secondary face 110 also has an inclined plane profile 112. Primary seal activation member 104 is axially movable along support rod 20 in response to increases in internal pressure upon activation of assembly 10. An annular secondary seal activation member 114 is provided having an inclined plane profile 116. Secondary seal activation member 114 is fixed in position to support rod 20. A secondary seal 118 is positioned between primary seal activation member 104 and secondary seal activation member 114. Referring to FIG. 8, secondary seal 118 has a plurality of sealing segments 120 arranged around the circumference of support rod 20, where, referring again to FIG. 7, each of the sealing segments 120 have an outwardly angled first end 122 and an outwardly angled second end 124. Referring to FIG. 9, upon movement of primary seal activation member 104 along support rod 20 toward secondary seal activation member 114, secondary seal 118 is sandwiched between primary seal activation member 104 and secondary seal activation member 114. Sealing segments 120 are then forced outwardly as outwardly angled first end 122 is forced up inclined plane profile 112 on secondary face 110 of primary seal activation member 104 and outwardly angled second end 124 is forced up inclined plane profile 116 of secondary seal activation member 114. Referring to FIG. 7, an expandable resilient band 125 is located in groove 130 and is used to urge sealing segments 120 of secondary seal 118 from the position shown in FIG. 10 back into engagement with support rod 20 as shown in FIG. 8. Resilient band 125 urges sealing segments 120 by encircling sealing segments 120 of secondary seal 118 and pulling sealing segments 120 back into engagement with the support rod 20. Other means will be apparent to those skilled in the art, for example, springs 126 may also be positioned on an exterior surface 128 of each of the sealing elements 120 around the circumference of secondary seal 118. In this instance, springs 126 push sealing segments 120 of secondary seal 118 back into engagement with support rod 20. In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the Claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The systems currently used to seal perforations have a fundamental flaw. They form a restriction in the well. This creates a problem should there later arise a need to seal other perforations further down in the well. U.S. Pat. No. 4,069,573 (Rogers 1978) (reissued as RE30,802 in 1981) discloses an invention entitled a “method of securing a sleeve within a tube”. This type of sleeve was developed to repair heat exchangers associated with nuclear power generation plants. The sleeves are positioned within the tube, and then expanded outwardly to engage the tube. In accordance with the teachings of the Rogers patent, the sleeves are expanded using hydraulics or by applying a compressive force to an elastomer material. U.S. Pat. No. 4,793,382 (Szalvay 1988) discloses an assembly for repairing a damaged pipe. The Szalvay reference contains a discussion of the shortcomings of the prior art apparatus used to expand sleeves. Some of such apparatus leave components in the damaged pipe, thereby restricting subsequent fluid flow. Others of such apparatus must be repositioned and then re-expanded at intervals along the sleeve. The Rogers reference is criticized as not being suitable where a leak proof fit is necessary; as is the teaching of the Rogers reference of using the sleeve to expand the damaged pipe. The Szalvay reference addresses these shortcomings by advocating the use of shape memory alloy elements. None of the prior art references address how a sleeve might be installed at a distance of several miles down a hydrocarbon producing well to seal off perforated zones or possibly repair damaged sections of conduit. | <SOH> SUMMARY OF THE INVENTION <EOH>What is required is a method and apparatus for positioning sleeves down hole in a hydrocarbon producing well. According to one aspect of the present invention there is provided a method for positioning sleeve down hole in a hydrocarbon producing well. A first step involves running a running assembly with associated sleeve down a hydrocarbon producing well until the sleeve is in a desired positioned in a conduit. The running assembly includes a first seal assembly sealing a first end of the sleeve and a second seal assembly sealing a second end of the sleeve. The first seal assembly and the second seal assembly have seals adapted to sequentially fail to expand the first end and the second end of the sleeve and to permit the second seal assembly to exit the second end of the sleeve and release the pressure when a preset threshold is reached. A second step involves expanding the sleeve until the sleeve sealingly engages the conduit. A third step involves maintaining pressure within the sleeve as the seals of the first seal assembly and the second seal assembly sequentially fail to expand the first end and the second end of the sleeve and until the preset threshold is reached, at which threshold pressure the second seal assembly exits the second end of the sleeve to relieve the pressure. A fourth step involves pulling the running assembly back through the expanded sleeve to surface. The expanded sleeve providing sufficient internal clearance that a further sleeve of the same size as the original may, in future, be passed through the expanded sleeve and positioned lower down in the well. According to another aspect of the present invention there is provided an assembly for positioning a sleeve down hole in a hydrocarbon producing well. A sleeve is provided having an interior surface, an exterior surface, a first end and a second end. The sleeve is made of a material which is capable of expanding radially when pressure is applied to the interior surface. A running tool support rod extends axially through the sleeve. The support rod has a first end, a second end, and an exterior surface. A first seal assembly is positioned at the first end of the sleeve. The first seal assembly has more than one annular seal. Each annular seal engages the exterior surface of the support rod and the interior surface of sleeve. A second seal assembly is positioned at the second end of the sleeve. The second seal assembly has more than one annular seal. Each annular seal engages the exterior surface of the support rod and the interior surface of sleeve. A first centralizer is positioned at the first end of the sleeve and is adapted to centralize the first end of the sleeve. A second centralizer is positioned at the second end of the sleeve and is adapted to centralize the second end of the sleeve. Means are provided for preventing outermost seals of the more than one seals of each of the first seal assembly and the second seal assembly from exiting the sleeve until the sleeve has been fully expanded and a preset pressure threshold has been reached. Means are provided for selectively expanding the sleeve by remote activation from surface. The method and apparatus, as outlined above and hereinafter further described, represents a significant advance in the art. It seals perforations with negligible restriction, so that it is possible to subsequently pass equipment through and seal perforations lower down in the well. As will hereinafter be further described, the preferred means for maintaining the outermost seal of the second seal assembly in position until the sleeve is fully expanded is to secure a shear sleeve to the support rod by shear screws. The shear sleeve provides containment to prevent an outermost seal of the second seal assembly from exiting the sleeve and relieving the pressure until the sleeve has been fully expanded. The shear screws are adapted to shear when a preset pressure threshold is reached. As will hereinafter be further described, the preferred mean for expanding the sleeve is to provide a combustion chamber for the combustion of a gas generating medium. An electric igniter element is provided in the combustion chamber and an electrical conduit extends from surface to facilitate remotely igniting the gas generating medium by sending an electrical current from surface to the electric igniter element. An expansion chamber is provided adjacent to the combustion chamber, to accommodate rapidly expanding gases generated by the combustion of the gas generating medium in the combustion chamber. Although the sleeve could be expanded using only gases, the combustion of gas generating medium tends to leave a residue. It is, therefore, preferred that a fluid chamber be provided which is filled with liquid. The fluid chamber is in fluid communication with the sleeve, which is also filled with liquid. The fluid chamber has a first end and a second end. A fluid conduit extends axially through the support rod from the second end of the fluid chamber to a feed inlet positioned between the first seal assembly and the second seal assembly. A piston is provided having a first face and a second face. The piston is positioned at the first end of the fluid chamber remote from the sleeve. The piston is axially movable in the fluid chamber when a force acts upon the first face of the piston. The first face of the piston is exposed to rapidly expanding gases in the expansion chamber. The rapidly expanding gases serve as a motive force to move the piston toward the second end of the fluid chamber, thereby exerting a hydraulic force upon liquid to expand the sleeve. | 20040326 | 20061031 | 20060727 | 63165.0 | E21B2300 | 0 | THOMPSON, KENNETH L | METHOD AND APPARATUS FOR POSITIONING A SLEEVE DOWN HOLE IN A HYDROCARBON PRODUCING WELL AND PIPELINES | SMALL | 0 | ACCEPTED | E21B | 2,004 |
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10,811,661 | ACCEPTED | Orthopedic intramedullary fixation system | A system and method for repairing fractured long bones. A guide wire is inserted through an opening drilled in a proximal bone segment and pushed through the intramedullary cavity of the proximal bone segment, across the fracture site and into the intramedullary cavity of a distal bone segment. A dilator is inserted over the guide wire and pushed through the intramedullary cavity into the distal bone segment to a stop at the distal end of the guide wire. A flexible tube having a radially expandable distal portion is then pushed over the guide wire into the distal bone segment and against the dilator. A compression nut is threaded over the proximal end of the guide wire to engage the proximal bone segment and compress the flexible tube. Compression of the flexible tube deploys the radially expandable distal portion to anchor the device in the distal bone segment. | 1. A bone segment positioning apparatus comprising: a guide wire having a proximal end and a distal end; a distal stop disposed on said guide wire about adjacent to said guide wire distal end; a proximal stop disposed on said guide wire about adjacent to said guide wire proximal end; and a tube disposable over said guide wire and having a sidewall including a radially expandable anchor portion adapted for radial expansion upon compression of said tube between said distal stop and said proximal stop. 2. The apparatus according to claim 1 further comprising a dilator having a tapered distal surface, an at least partially transverse proximal surface and a tubular inner surface defining a longitudinal through hole; said dilator being disposable on said guide wire wherein said guide wire extends through said through hole; wherein said at least partially transverse proximal surface serves as said distal stop. 3. The apparatus according to claim 2 wherein said at least partially transverse proximal surface is countersunk to accept said tube. 4. The apparatus according to claim 2 wherein said tapered distal surface includes means to prevent rotation of said dilator relative to said guide wire. 5. The apparatus according to claim 4 wherein said guide wire includes a distal tip having a diameter greater than the diameter of said longitudinal through hole. 6. The apparatus according to claim 5 wherein said means to prevent rotation comprise a polygonal mating surface adapted to fit an opposite gendered polygonal mating surface of said distal tip. 7. The apparatus according to claim 1 wherein said proximal stop is formed as a distal surface of a compression fastener disposed over said proximal end of said guide wire. 8. The apparatus according to claim 7 wherein said compression fastener comprises at least one nut threaded onto said proximal end of said guide wire. 9. The apparatus according to claim 7 wherein said compression fastener includes an interface washer adapted to engage a proximal bone segment. 10. The apparatus according to claim 1 wherein said tube and guide wire are flexible. 11. The apparatus according to claim 1 wherein said radially expandable anchor portion comprises a plurality of ribs formed between a plurality of longitudinal slots disposed through said sidewall. 12. The apparatus according to claim 1 wherein said radially expandable anchor portion is disposed toward said distal end. 13. The apparatus according to claim 10 wherein said ribs include at least one reduced section formed in a central portion of each rib. 14. The apparatus according to claim 13 wherein said at least one reduced section comprises a crease formed transversely across said central portion of each rib. 15. The apparatus according to claim 13 wherein said at least one reduced section comprises a narrowed section of each rib. 16. The apparatus according to claim 11 wherein said plurality of rib portions comprise at least two evenly spaced ribs. 17. The apparatus according to claim 1 wherein said radially expandable anchor portion is adapted to collapse upon relaxation of compression forces between distal and proximal segments of said tube. 18. The apparatus according to claim 1 wherein said radially expandable anchor portion is adapted to collapse upon application of tension between distal and proximal segments of said tube. 19. The apparatus according to claim 1 further comprising a bioactive material. 20. The apparatus according to claim 1 comprising a plurality of radially expandable anchor portions. 21. The apparatus according to claim 11 wherein at least one of said ribs includes a textured surface. 22. The apparatus according to claim 1 further comprising at least one semi-annular cut in said tube. 23. A long bone segment positioning apparatus comprising: a flexible guide wire having a proximal end and a distal end; a distal stop disposed on said guide wire about adjacent to said guide wire distal end; a proximal stop disposed on said guide wire about adjacent to said guide wire proximal end; a flexible tube disposable over said guide wire and having a sidewall including a radially expandable anchor portion adapted for radial expansion upon compression of said tube between said distal stop and said proximal stop; a dilator having a tapered distal surface, an at least partially transverse proximal surface and a tubular inner surface defining a longitudinal through hole; said dilator being disposable on said guide wire wherein said guide wire extends through said through hole; wherein said at least partially transverse proximal surface is countersunk to accept said tube and serves as said distal stop; wherein said guide wire includes a distal stop having a width greater than the diameter of said longitudinal through hole; wherein said proximal stop is formed as a distal surface of an interface washer installed over said proximal end of said guide wire; wherein said radially expandable anchor portion comprises a plurality of evenly spaced ribs formed between a plurality of longitudinal slots disposed through said sidewall; wherein said radially expandable anchor portion is disposed toward said distal end for engagement with a distal bone segment; wherein said ribs include at least one reduced section formed in a central portion of each rib segment; and wherein said radially expandable anchor portion is adapted to collapse upon relaxation of compression forces between distal and proximal segments of said tube. 24. A method for aligning bone segments comprising: installing a tube in an intramedullary space spanning a fracture; anchoring a portion of said tube to a first side of said fracture; compressing said tube to radially expand an expandable anchor portion of said tube on a second side of said fracture. 25. The method according to claim 24 further comprising: installing a guide wire in said intramedullary space spanning said fracture; wherein said tube is installed over said guide wire; and wherein said tube is compressed between stops on said guide wire. 26. The method according to claim 25 further comprising installing a tapered dilator over said guide wire prior to installing said tube over said guide wire; wherein said dilator includes a transverse portion which serves as one of said stops. 27. The method according to claim 25 wherein said step of anchoring a portion of said tube to a first side of said fracture comprises installing an anchor nut over a proximal end of said guide wire. 28. A method for aligning fractured bone segments comprising: installing a guide wire in an intramedullary space spanning said fracture; installing a flexible tube over said guide wire in said intramedullary space spanning a fracture; anchoring a portion of said flexible tube to a first side of said fracture; compressing said flexible tube to between stops on said guide wire to radially expand an expandable anchor portion of said flexible tube on a second side of said fracture. 29. The method according to claim 25 further comprising installing a tapered dilator over said guide wire prior to installing said tube over said guide wire; wherein said dilator includes a transverse portion which serves as one of said stops. 30. The method according to claim 25 wherein said step of anchoring a portion of said tube to a first side of said fracture comprises installing an interface washer over a proximal end of said guide wire. 31. The method according to claim 25 further comprising: drilling into said intramedullary space in a proximal bone segment; and reaming said intramedullary space. 32. The method according to claim 25 further comprising: releasing compression on said flexible tube to allow said expandable anchor portion to retract for removal of said tube and guide wire upon healing of said bone segments. | FIELD OF THE INVENTION This invention relates generally to an orthopedic support system and apparatus and more particularly to an intramedullary (IM) support apparatus and method of use thereof for supporting fractured long bones. The IM support apparatus according to the present invention is minimally invasive and provides improved alignment of bone segments. BACKGROUND OF THE INVENTION Various methods and apparatus have long been used for positioning, stabilizing and supporting bone segments to repair bone fractures in humans and animals. Simple external apparatus such as slings and splints are well known and are still used alone or in combination with invasive apparatus to repair broken bones. Slings are used alone in certain circumstances where use of invasive apparatus or implants presents an unacceptable risk of injury to a patient. For example, slings are often used without any invasive apparatus to repair a fractured clavicle because implantation of known invasive bone repair apparatus to repair a fractured clavicle can risk life threatening damage to the patient's subclavian artery or damage to other vessels, nerves, nerve bundles, vital organs or surrounding tissues. Since invasive repair of a fractured clavicle presents medical risk, patients having a fractured clavicle often forgo the benefits offered by various invasive apparatus and implants. Such benefits which include improved bone segment positioning, stabilizing and support promote more rapid recovery and reduce patient discomfort. Further, use of slings alone often allows misaligned bone segments to heal such that a visibly conspicuous deformation or a weak area remains which is susceptible to re-injury. Accordingly, it would be advantageous to provide a clavicle repair apparatus with reduced risk of injury to the patient. Known invasive apparatus for bone segment repair include various configurations of bone fracture reduction rods, orthopedic screws, intramedullary nails, intramedullary screws and the like. For example, U.S. Pat. No. 6,338,732 to Yang discloses an in-marrow nail structure having two threaded ends for drilling and engaging fractured bone segments. A nut is screwed over a threaded proximal portion of the structure to apply compressive force to the bone segments. The apparatus disclosed in Yang and similar devices involve installing a drilling tip within the intramedullary cavity. These devices typically incorporate threads having a cutting edge in at least a distal portion whereby drilling is performed by rotating the devices around their longitudinal axis. Accordingly, such devices are typically unsuitable for implantation in curved bone segments. Such devices also present a high risk of drilling through a bone segment into surrounding tissue, and are therefore not well suited for use in repairing a fractured clavicle. It would be desirable to provide an intramedullary apparatus that is suitable for use in curved bone segments without presenting a high risk of damaging surrounding tissue. In addition to providing a drilling capability for implanting an intramedullary device, the threaded distal portion of some known devices serves as an anchor which secures the distal portion of the device to a distal bone segment. Bone segments are held together by also providing a compressing portion which engages the proximal bone segment and travels toward the anchored distal portion. In another type of known intramedullary support apparatus, an expandable anchor portion is provided for engaging the distal bone segment. For example, U.S. Pat. Nos. 3,779,239; 3,760,802 and 4,227,518 disclose particular intramedullary retraction nails that include an expansion element in their distal portion. The expansion elements serves as an anchor in a distal bone segment. The aforementioned devices are generally directed toward a rod disposed with a tubular portion. Relative linear motion between the rod and the tubular portion, such as by threading the rod to the tubular portion, causes actuation of the expansion element to engage the bone lining in the distal portion. A bolt head and or nut and washer are installed over or incorporated with the proximal portion of the rod which protrudes from a hole drilled in the proximal bone segment. In the apparatus disclosed in U.S. Pat. Nos. 3,779,239 and 3,760,802 the central rod is curved to correspond with the curvature of the bone under repair. Installation of a rod within the intramedullary cavity can increase the risk of damage to the bone lining, and can be difficult to perform on curved bones such as the clavicle. Furthermore, apparatus heretofore known that are adapted for providing a distal anchor portion are not adapted for aligning a displaced fracture. Insertion of such devices to a misaligned fracture can cause increased separation of bone segments and possibly damage surrounding tissue. The rod's rigidity can also prevent it from centering radially when the expandable anchor portion is deployed. Such devices can therefore allow a bone to heal in a misaligned or overlapped state which can be weak or appear deformed. It would therefore be desirable to provide a intramedullary support device for use on curved bone segments that does not include a rigid internal rod portion, and which is self centering and adapted to align bone segments at a displaced fracture site. Known IM fixation devices having an expandable anchor portion are typically constructed with a number of separate moving components. The number of moving components can make such devices expensive and susceptible to malfunction. It would be desirable to provide an IM fixation device having an expandable anchor portion which does not require a large number of separate components. The proximal portion of known IM fixation devices is often movably disposed within the IM region of the proximal portion of a fractured clavicle bone. Such proximal portions of the device protrude from the posterior lateral end of the clavicle bone. A stabilizing nut is typically rotated to engage the threaded portion of the IM fixation device, thus causing the stabilizing nut to partially traverse the threaded portion of the IM fixation device. As the stabilizing nut traverses the threaded portion, the stabilizing nut pushes the proximal portion of the fractured clavicle bone toward the distal portion of the fractured clavicle bone. The stabilizing nut is rotated until the distal and proximal portions of the fractured clavicle bone contact each other, such that the fractured ends of the clavicle bone remain in contact with each other to allow for the accelerated healing of the clavicle fracture. Several heretofore known IM fixation devices include portions that prominently protrude from the proximal lateral end of the clavicle bone. Even small movement of such devices can causes extreme pain to a patient. It would therefore be desirable to provide an intramedullary fixation device that does not prominently protrude externally from the bone. Installation of some known intramedullary support devices involves invasive surgery wherein a cut-down must be performed at the fracture site. Such surgical installations increase the risk of infection, lengthen the recovery period, and often leave large unsightly scars. It would therefore be desirable to provide a method and apparatus for repairing fractured bones which is minimally invasive and which does not require a surgical cut-down at the fracture site. Many known intramedullary support devices are not fixed within the intramedullary space and can therefore suffer from migration within the intramedullary space. It has been known for intramedullary devices or components thereof to migrate such that they pierce a patient's surrounding tissue, skin, or vital organs. It would therefore be desirable to provide an intramedullary support device that does not suffer from migration. Many heretofore known intramedullary fixation devices are difficult to remove after a patient's fractured bone has healed. It would therefore be desirable to provide an intramedullary support device that is more easily removed from the bone after a fracture has healed. SUMMARY OF THE INVENTION The present invention provides a method and apparatus for minimally invasive fixation and repair of fractured long bones. The term “long bone” is used generally throughout the present specification and is meant to include any human or animal bone having sufficient intramedullary space for installation of the various embodiments of the invention described below. For example, various embodiments of the invention are described with respect to repair of a fractured collar bone in humans. It should be understood that the invention also includes a method and apparatus for repairing various other bones in humans in animals such as bones in the upper and lower extremities as well as smaller bones, including bones in human hands and fingers. According to an illustrative embodiment of the present invention, an opening is made into the intramedullary cavity toward a proximal end of a proximal bone segment. A guide wire is inserted through the opening and pushed through the intramedullary cavity of a proximal bone segment, across the fracture site and into the intramedullary cavity of a distal bone segment. A dilator having longitudinal through-hole and a tapered leading surface is inserted over the guide wire and pushed through the intramedullary cavity into the distal bone segment to a stop at the distal end of the guide wire. The tapered leading surface of the dilator is adapted to aid in the alignment of bone segments as it is pushed across the fracture site. A flexible tube having a radially expandable distal portion is then pushed over the guide wire into the distal bone segment and against the dilator. The expandable distal portion of the tube is deployed by compressing the flexible tube between its proximal end and the dilator. Compression of the flexible tube can be performed by threading a compression nut onto the proximal end of the guide wire. The distal stop on the guide wire prevents the dilator and flexible tube from moving further distally so that compression is applied to the flexible tube between the dilator and the compression nut. The compression nut and/or a washer disposed with the compression nut are adapted to engage the proximal bone segment so that the proximal and distal bone segments are pulled together. One embodiment of the present invention provides a bone segment positioning apparatus including a guide wire having a proximal end and a distal end. A distal stop is disposed on the guide wire about adjacent to the guide wire distal end. A proximal stop disposed on the guide wire about adjacent to the guide wire proximal end. A tube is disposed over the guide wire. The tube has a sidewall including a radially expandable anchor portion adapted for radial expansion upon compression of the tube between the distal stop and the proximal stop. At least one embodiment also includes a dilator having a tapered distal surface, an at least partially transverse proximal surface and a tubular inner surface defining a longitudinal through hole. The dilator is disposable on the guide wire wherein the guide wire extends through the through hole. The at least partially transverse proximal surface serves as the distal stop. In a particular embodiment, the at least partially transverse proximal surface can also be countersunk to accept the tube. The tapered distal surface can include means to prevent rotation of the dilator relative to the guide wire. Such means can be manifest, for example in a hexagonal depression in the tapered surface that mates with a hexagonal anti-rotation feature fixed to the guide wire. For example in one embodiment, the guide wire includes a spherical distal tip having a diameter greater than the diameter of the longitudinal through hole. The means to prevent rotation in this embodiment include a polygonal mating surface of the tapered surface adapted to fit an opposite gendered polygonal mating surface of the spherical distal tip. Persons having ordinary skill in the art should appreciate that a large number of anti-rotation features such as key/slot features, interference fits, wedges and the like could be substituted as anti-rotation means within the scope of the present invention. In one embodiment, the tube and guide wire are flexible. The proximal stop is formed as a distal surface of a compression fastener over the proximal end of the guide wire. The compression fastener comprises at least one nut threaded onto the proximal end of the guide wire. The radially expandable anchor portion includes a plurality of rib portions formed between a plurality of longitudinal slots disposed through the sidewall. The radially expandable anchor portion is disposed toward the distal end for engagement with a distal bone segment. In an illustrative embodiment, the rib portions include at least one reduced section formed in a central portion of each rib segment. The at least one reduced section can include a crease formed transversely across the central portion of each rib segment. Alternatively the at least one reduced section comprises a narrowed section of each rib segment. The at least one reduced section could also be creased and narrowed, for example. In a particular embodiment, the plurality of rib portions comprise at least two evenly spaced rib portions. The radially expandable anchor portion is also adapted to collapse upon relaxation of compression forces between distal and proximal segments of the tube. In another embodiment, the radially expandable anchor portion is adapted to collapse upon application of tension between distal and proximal segments of the tube. In another embodiment, the invention provides a method for aligning fractured bone segments. The method includes installing a tube in an intramedullary space spanning a fracture, anchoring a portion of the tube to a first side of the fracture, and compressing the tube to radially expand an expandable anchor portion of the tube on a second side of the fracture. In one embodiment, the method also includes installing a guide wire in the intramedullary space spanning the fracture. The tube is installed over the guide wire and compressed between stops on the guide wire. Anchoring a portion of the tube to a first side of the fracture can be performed, for example, by installing an anchor nut which engages the bone segment over a proximal end of the guide wire. The method can also include installing a tapered dilator over the guide wire prior to installing the tube over the guide wire. The dilator includes a transverse portion which serves as one of the stops. In the illustrative embodiment of the invention, the method also includes drilling into the intramedullary space in a proximal bone segment; and reaming the intramedullary space. The method can also include releasing compression on the flexible tube to allow the expandable anchor portion to retract for removal of the tube and guide wire upon healing of the bone segments. Advantages of the invention include provision of a bone segment positioning device and methodology that involves a safer, minimally invasive surgical procedure which allows for substantially less pain and discomfort for a patient. Further advantages of the invention include the ability to repair fractured bones without the need for “cut-down” at the fracture site, thus greatly reducing or eliminating any nerve and blood vessel disturbance and risk of infection. An additional advantage of the invention is that the bone segment positioning device is easily removable and malleable. The malleability of the device adds an extra degree of safety because the device will bend rather than applying potentially damaging lateral pressures in the IM cavity. The present invention overcomes the deficiencies of the prior art by providing a clavicle repair apparatus with reduced risk of injury to the subclavian artery. An intramedullary apparatus is provided that is suitable for use in curved bone segments without presenting a high risk of damaging surrounding tissue. The various embodiments of the present invention also provide an intramedullary support device for use on curved bone segments that does not include a rigid internal rod portion, and which is self centering and adapted to align bone segments at a displaced fracture site. Further, the present invention provides an IM fixation device having an expandable anchor portion which does not require a large number of separate components and does not prominently protrude externally from the bone. The various embodiments of the present invention also provide a method and apparatus for repairing fractured bones which is minimally invasive and which does not require a surgical cut-down at the fracture site BRIEF DESCRIPTION OF DRAWINGS The foregoing and other features and advantages of the present invention will be better understood from the following detailed description of illustrative embodiments, taken in conjunction with the accompanying drawings in which: FIG. 1 is a side cross sectional view of a long bone compression apparatus according to an illustrative embodiment of the present invention; FIG. 2 is a plan view of a guide wire according to an illustrative embodiment of the present invention; FIG. 3 is a cross sectional view of a dilator according to an illustrative embodiment of the present invention; FIG. 4 is a cross sectional view of an inner tube according to an illustrative embodiment of the present invention; FIG. 5 is a cross sectional view of an outer tube according to an illustrative embodiment of the present invention; FIG. 6 is a cross sectional view of an interface washer according to an illustrative embodiment of the present invention; FIG. 7 is a cross sectional view of a compression nut according to an illustrative embodiment of the present invention; FIG. 8 is a cross sectional view of a fractured long bone illustrating the method of inserting a guide wire according to an illustrative embodiment of the present invention; FIG. 9 is a cross sectional view of a fractured long bone illustrating a method of installing a dilator according to an illustrative embodiment of the present invention; FIG. 10 is a cross sectional view of a fractured bone segment having a guide wire and a dilator installed according to an illustrative embodiment of the present invention; FIG. 11 is a cross sectional view of a fractured bone segment having a guide wire, dilator and outer tube installed in the intramedullary cavity according to an illustrative embodiment of the present invention; FIG. 12 is a cross sectional view of a fractured long bone having an intramedullary fixation apparatus according to an illustrative embodiment of the present invention installed therein with an expanded anchor portion; FIG. 13 is a cross sectional view of a drill guide suitable for use in methods of installing the intramedullary device according to the present invention; FIG. 14 is a cross sectional view of a fractured long bone having an intramedullary fixation apparatus installed therein and illustrating the use of an external fixation device in conjunction with the intramedullary fixation apparatus according to an illustrative embodiment of the present invention; and FIG. 15 is a pictorial view of a partially assembled intramedullary fixation apparatus according to an alternative embodiment of the invention including an outer tube having a plurality of semi-annular cuts. DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, the components of a long bone compression apparatus 10 having a proximal end 12 and a distal end 14 according to the an illustrative embodiment of the invention are shown assembled together in a cross sectional view. A guide wire 16 extends from the distal end 14 to the proximal end 12 of the compression apparatus and includes a threaded portion 17 on the proximal end of the guide wire 16 and a distal end stop 18 disposed on the distal end of the guide wire 16. A dilator 20 is disposed over the guide wire 16 adjacent to the distal end stop 18. As disclosed herein, the term ‘distal’ refers to the element or portion furthest from the threaded portion 17 of the guide wire 16 and the term ‘proximal’ refers to the element or portion closest to the threaded portion 17 of the guide wire 16. In the embodiment shown in FIG. 1, an inner tube 21 is disposed over the guide wire 16 and an outer tube 22 is disposed over the inner tube 21. Both the inner tube 21 and outer tube 22 abut the dilator 20. An interface washer 24 is disposed over the threaded portion of the guide wire and abuts the proximal end of the outer tube 22. A nut 26 is threaded onto the threaded portion 17 of the guide wire 17 and abuts the interface washer 24. At least one slot 28 extends through the outer tube 22. In FIG. 2, an illustrative embodiment of a guide wire 16 according to the present invention is shown. The guide wire 16 includes a distal end stop 18. The end stop 18 can be formed integrally with the guide wire 16 or can be a separate component assembled securely thereto. In the embodiment of FIG. 2, the end stop has a spherical shape. Persons skilled in the art should appreciate that the end stop could be made in virtually any shaped radial protrusion of sufficient length formed with or fixed to the distal end of the guide wire. The end stop 18 must extend radially beyond the outside surface of the guide wire by a distance greater than the diameter of a through hole in the dilator 20 through which the guide wire passes. In at least one embodiment of the invention, the end stop 18 includes anti-rotation surfaces such as a hexagonal outside surface for mating with a hexagonal cavity in the dilator. In another embodiment, the end stop 18 can be formed as a T shape at the distal end of the guide wire. The T shaped end stop can prevent rotation of the dilator 20 relative to the guide wire 16 if a dilator 20 having a mating slot in its distal portion which accepts the T shaped end stop. The proximal end of the guide wire has a threaded exterior surface for engagement with a compression nut. In the illustrative embodiment the threads are a 0-80 UNF thread extending 0.620 inches from the proximal end of the guide wire. Persons skilled in the art should appreciate that a number of different thread sizes could be substituted for engagement with a compression nut according to the present invention and that the threads can extend along a length shorter or longer than the length shown in FIG. 2. It is envisioned, for example, that an alternative embodiment of the invention could be constructed using a guide wire having a threaded surface along its entire length. In the illustrative embodiment, the guide wire has a circular cross section and is made from TI6AL-4AV ELI Alloy per ASTM F160. Persons skilled in the art should appreciate that the guide wire could alternatively be made from a number of clinically suitable materials such as stainless steel, molded or extruded polymers and the like. It is envisioned that a guide wires having a different cross sectional geometry can also be used in alternative embodiments of the invention. For example, it is envisioned that a flat steel band could be substituted for a circular cross sectional guide wire in alternative embodiments of the invention. Although the guide wire is described herein generally in terms of a flexible wire, persons skilled in the art should appreciate that the guide wire can be made from a flexible rod or elongated flexible structure. In FIG. 3, an illustrative embodiment of a dilator 20 according to the present invention is shown. In the illustrative embodiment, the dilator 20 has a circular cylindrical body portion 22 and a tapered distal portion 24. A cylindrical through hole 26 extends through the center of the dilator along its longitudinal axis. The through hole diameter is greater than the diameter of the guide wire to facilitate travel of the dilator along the guide wire up to the distal end stop of the guide wire. The dilator 20 can also include one or more counter bores in its proximal end to accept one or more tubes disposed over the guide wire. In the embodiment shown in FIG. 3, the dilator 20 includes an inner counter bore 28 for accepting an inner tube disposed over the guide wire 16 and an outer counter bore 30 for accepting an outer tube disposed over the guide wire 16. In the illustrative embodiment, the counter bores include tapered portions adapted for mating with tapered distal ends of a respective tube. In the embodiment shown in FIG. 3, the dilator 20 includes a transverse slot 32 extending across its tapered distal portion 24. The slot 32 is adapted to accept an anti-rotation surface of the guide wire end stop 18. In the illustrative embodiment, the dilator 20 is made from TI6AL-4V ELI Alloy per ASTM F133. Persons skilled in the art should appreciate that a number of alternative materials could alternatively be used to fabricate a dilator 20 according to the present invention. For example, stainless steel or medically suitable polymers and the like can be used to fabricate a dilator 20 within the scope of the present invention In FIG. 4, an inner tube 21 as used in a particular embodiment of the present invention is shown. The inner tube 21 has a tapered distal end 34 for engagement with the inner counter bore 28 (FIG. 3) in the dilator 20. An internal cavity 36 adapted for sliding over the guide wire 16 extends along the full length of the inner tube 21 along its longitudinal axis. Alternatively, it is envisioned that the invention could also be practiced using a guide wire and inner tube that are engaged by threading one with the other. In such an embodiment a threaded internal cavity is adapted for threading onto a threaded guide wire. In the illustrative embodiment shown in FIG. 4, the inner tube 21 is made from nitinol tubing having a 0.090″ outside diameter and a 0.062″ inside diameter. Nitinol is a particularly suitable material for use in components of an IM fixation device because it has stress/strain characteristics that approximate the stress/strain characteristic of human and animal bones. Persons skilled in the art should appreciate that a number of different materials could be used having a number of different inside and outside diameters to substitute for the illustrative inner tube 21 within the scope of the present invention. Since a function of the inner tube 21 in an illustrative embodiment is to push the dilator 20 along the guide wire 16 to the distal stop 18, inner tube material and inner tube dimensions of such embodiments should have sufficient rigidity to force the dilator 20 along the guide wire 16 even when resistance is presented by friction in the IM cavity, for example when the dilator traverses a misaligned fracture site. In embodiments of the invention intended for use in curved long bones, the inner tube 21 should be sufficiently flexible to travel around curves in the IM cavity of the curved bone. Although the various embodiments of the invention are described herein as having an inner tube 21 with a generally circular cross-section, persons skilled in the art should appreciate that an inner tube having a different cross-sectional shape, such as for example, an oval or polygon could be substituted therefore without departing from the spirit and scope of the invention. In FIG. 5, an illustrative embodiment of an outer tube according to the present invention is shown. The outer tube 22 has a tapered distal end 38 for engagement with the outer counter bore of the dilator 20. Alternative embodiments of the invention can be practiced using an outer tube 22 without a tapered distal end. For example, persons skilled in the art should appreciate that certain embodiments of the present invention can be practiced without any counter bore in the dilator 20. In these and other alternative embodiments, an outer tube 22 having a non-tapered distal end can be used. An internal cavity 40 adapted for sliding over the inner tube 21 extends along the full length of the outer tube 22 along its longitudinal axis. Persons skilled in the art should appreciate that the internal cavity 40 could alternatively be threaded for engagement with an inner tube 21 having a threaded outer surface. In other alternative embodiments of the present invention no inner tube 21 is used. In such embodiments, the internal cavity 40 of the outer tube 22 is adapted for sliding over or threading over the guide wire. In the embodiment shown in FIG. 5, the outer tube 22 is made from nitinol tubing having a 0.140″ outside diameter and a 0.105″ inside diameter. Persons skilled in the art should appreciate that a number of different materials could be used having a number of different inside and outside diameters to substitute for the illustrative inner tube 21 within the scope of the present invention. In embodiments of the invention intended for use in curved long bones, the outer tube 22 should be sufficiently flexible to travel around curves in the IM cavity of the curved bone. Although the various embodiments of the invention are described herein as having an outer tube 22 with a generally circular cross-section, persons skilled in the art should appreciate that an inner tube having a different cross-sectional shape, such as for example, an oval or polygon could be substituted therefore without departing from the spirit and scope of the invention. At least one slot 42 defines an anchor portion of the outer tube. In the illustrative embodiment, four slots having uniform annular spacing extend through the outer tube toward the proximal end of the tubing to define the anchor portion 44. The four slots 42 define four ribs 46 therebetween which are designed to collapse radially outward upon compression of the outer tube between its ends. In an illustrative embodiment of the invention, the four ribs are also designed to regain their approximate original shape upon relaxation of the compressive force. In the illustrative embodiment shown in FIG. 5, the slots are 1″ long and 0.062″ wide having a full radius at either end. Persons skilled in the art should appreciate that various rib dimensions by the various slot dimensions and various numbers of ribs and slots can be used in alternative embodiments of the present invention. It should be understood that the rib 46 and slot 42 dimensions are critical to the functionality of the anchor portion 44 and will depend upon the mechanical properties of the material used for fabricating the outer tube and the thickness of the outer tube wall. In other alternative embodiments of the present invention slots between the ribs 46 of the anchor portion 44 are shaped to define a folding location on the rib 46. For example the slots 42 can have a wider section at the midpoint of their length to create a narrower portion of each rib 46 formed between two such slots 42. The narrower portion of such ribs 46 at the midpoint of their length can provide a folding location on the rib 46. Other structures that could be used to create a folding location include an internal annular groove, an external annular groove, a perforation, an embossment or the like. It is envisioned that in still another embodiment of the present invention, a folding portion can be formed by dividing ribs 46 at the folding location and installing a hinges between rib segments. It is envisioned that alternative embodiments of the invention will include gripping portions (not shown) configured on one or more of the ribs 46 to provide increased friction between the anchor portion 44 and the intramedullary wall. For example, it is envisioned that alternative embodiments of the invention will include textured rib portions, serrated rib portions and the like for improved engagement with the intramedullary wall when the anchor portion 44 is deployed. Although the various embodiments of the invention are described herein in terms of a single anchor portion 44, it is envisioned that alternative embodiments of the invention will be practiced using more than one anchor portion 44 disposed along the outer tube 22. In alternative embodiments, it is envisioned that the additional anchor portions (not shown) can be configured with different dimensions to cause a specific sequence of engagement upon application of compressive forces to the outer tube 22. In FIG. 6, an interface washer 24 according to an illustrative embodiment of the present invention is shown. The interface washer includes a through hole 50 extending along its longitudinal axis. The through hole 50 is adapted to fit over the guide wire 16. In an alternative embodiment the through hole 50 of the interface washer 24 can be threaded for threading engagement to a threaded portion of the guide wire 16. A concave proximal surface 52 is adapted for alignment with a convex distal surface 64 of a compression nut 26 (FIG. 7). Persons skilled in the art should appreciate that alternative embodiments of the present invention can be practiced by providing a convex proximal surface on the interface washer 24 and a concave distal surface on the compression nut 26 without including a concave or convex proximal surface in the interface washer 24 and/or compression nut 26. For example, it is envisioned that an interface washer having a flat proximal surface can be used with a flat compression nut without providing any alignment between the compression nut and interface washer. Alternatively a number of different surface combinations can be used to provide alignment between the interface washer and the compression nut while allowing relative rotation therebetween. In the illustrative embodiment shown in FIGS. 1 and 6, a step 54 is formed between a first outside diameter 56 adapted for fitting to the inside diameter of the outer tube 22 and a bone interface surface 58. The step 54 defines a compression surface 60 which abuts the proximal end of the outer tube 22. In the illustrative embodiment, the bone interface surface 58 is tapered outward in the proximal direction. The bone interface surface 58 engages a proximal bone segment by being pressed into a hole drilled in the proximal segment when a compression nut 26 is threaded to the guide wire 16. The outward tapering of the bone interface surface 58 in the illustrative embodiment allows the washer to be partially inserted into a drilled entry hole in a proximal bone segment to secure the proximal end of the apparatus 10 (FIG. 1) to the proximal bone segment. Persons skilled in the art should appreciate that the present invention can be practiced using a number of different types of bone interface surfaces. For example, it is envisioned that a stepped surface having serrations could be used as a bone interface surface in an alternative embodiment of an interface washer according to the present invention. In the alternative embodiment, the stepped surface would include a first surface fitting into the drilled entry hole and the step surface wider than the drilled entry hole having serrations for engaging the outside of the proximal bone. Flat portions 62 are provided on the surface of the interface washer 24 for engagement with an anti-rotation tool such as a wrench. In the illustrative embodiment shown in FIG. 6, a pair of parallel flat portions 62 are suitable for engagement with a wrench, pliers or other anti-rotation tool. Persons skilled in the art should appreciate that a number of different surface configurations can be provided on the interface washer to prevent rotation of the washer while the compression nut is installed. For example, the pair of flat portions 62 can be replaced by a hexagonal or other polygonal surface adapted for engagement by a wrench or a knurled surface adapted for being gripped by hand. Alternatively, it is envisioned that one or more radial arms could be provide extending from the proximal portion of the interface washer 24 for gripping to prevent rotation of the interface washer 24 when the compression nut 26 is installed. In the illustrative embodiment, the interface washer is made from TI6AL-4V ELI ALLOY PER ASTM F136. Persons skilled in the art should appreciate that an interface washer 24 according to the invention could alternatively be made from a number of different clinically suitable materials such as stainless steel, thermoplastic or the like. In FIG. 7, a compression nut 26 according to the present invention is shown. The compression nut 26 includes a convex distal surface 64 adapted for alignment in the concave proximal surface 52 of the interface washer 24. A threaded through hole 66 extends along the longitudinal axis of the compression nut 26. The threaded through hole is adapted for threading onto the threaded portion of the guide wire. Flat surfaces are provided for engagement with a rotation tool such as a wrench, nut driver, pliers or the like. Persons skilled in the art should appreciate that a number of different shaped tool engagement surfaces may be provided on the compression nut 26 for engaging a tool adapted to the particular shape for threading the compression nut 26 on the guide wire 16. It is also envisioned that the flat surfaces 68 can be replaced by a knurled surface adapted for being gripped by hand. Alternatively, it is envisioned that one or more radial arms could be provide extending from the compression nut 26 to aid in manual threading of the compression nut onto the guide wire 16. In the illustrative embodiment shown in FIG. 7 the compression nut is made from TI6AL-4V ELI ALLOY PER ASTM F136. Persons skilled in the art should appreciate that a compression nut 26 according to the invention could alternatively be made from a number of different clinically suitable materials such as stainless steel, thermoplastic or the like. A method of using the present invention will be described first with respect to FIGS. 8-12. It should be understood by persons skilled in the art that the methods of installing the present invention can be best performed using imaging technology such as fluoroscopic imaging techniques, ultrasonic imaging or the like to monitor positions of the various components of the apparatus during installation. As shown in FIG. 8, a hole 70 is drilled through the bone wall 71 into the IM cavity 76 toward the proximal end of a proximal bone segment 72 of a fractured bone. It should be understood the in the context of this disclosure the terms broken and fractured used in conjunction with a bone includes but is not limited to greenstick fractures, displace fractures, plastic deformity, torus (buckle) fractures, growth plate fractures, closed fractures, open (compound) fractures, comminuted fractures, pathological fractures, stress fractures and the like. The hole 70 must be wide enough to allow passage of the dilator 20, guide wire 16, outer tube 22 and (optionally) inner tube 21 but narrow enough to engage the bone interface washer 24 of the apparatus 10. In at least one embodiment of the invention a drill guide is used to align a drill bit at a constant orientation relative to the bone while drilling and to prevent the drill bit from drilling beyond the IM cavity. An exemplary drill guide 80 for use in the illustrative method of installing intramedullary support apparatus 10 of the present invention is shown in FIG. 13. The drill guide includes a hollow shaft 82 adapted for guiding a drill bit. The hollow shaft has a bone engagement surface 84 which can include features such as serrations to prevent slippage on the exterior surface of a bone. The hollow shaft also has a drill stop surface 86 displaced from the bone engagement surface 84 by a distance determined to allow a drill bit to enter the IM cavity but to prevent the drill bit from drilling beyond the IM cavity. A handle 88 extending from the shaft 82 allows the drill guide to be securely held in place during a drilling procedure. Once the hole is drilled, a guide wire 16 is inserted into the IM cavity and manually pushed across the fracture site 78 into the distal bone segment 74. The proximal portion of the guide wire 16 remains extending outside of the drilled hole 70. A dilator 20 is installed over the proximal end of the guide wire 16 and pushed into the IM cavity 76, across the fracture site 78 and into the IM cavity 76 of the distal bone segment 76. In at least one embodiment of the invention, as shown in FIG. 9, a flexible tube is used to push a dilator along the guide wire. A handle 92 can be used to allow better gripping leverage to manually push the flexible tube 90 from the proximal end. As the tapered distal portion of the dilator crosses a fracture site, the tapered surface engages the bone wall of the distal bone segment and tends to align the fractured bone segments with each other. As shown in FIG. 10, the dilator is pushed to the end stop disposed on the distal end of the guide wire. In this illustrative embodiment the flexible tube is removed once the dilator reaches the end stop. In an alternative embodiment, using an inner tube 21, the inner tube is used to push the dilator through the IM cavity. The inner tube 21 is then left in place and becomes part of the bone fixation apparatus 10. Next, as shown in FIG. 11, an outer tube 22 is installed by pushing the outer tube over the guide wire (and over the inner tube 21 if an inner tube is installed). The outer tube is pushed as far as possible until it is stopped by the proximal surface of the dilator 20. Once the outer tube 22 is fully installed, a bone interface washer is installed over the proximal end of the guide wire 16. A compression nut is then placed over the proximal end of the guide wire and threaded along the threaded portion of the guide wire. In the illustrative embodiment, the bone interface washer is wedged into the hole and held fixed while the compression nut is turned. When the compression nut reaches is prevented from traveling distally by the compression nut, further threading of the nut causes the nut to pull the guide wire in the proximal direction. While the proximal end of the outer tube 22 is prevented from moving distally by the bone interface washer 24, the distal end of the outer tube is pulled distally by the guide wire 16 and dilator 20. The outer tube 22 is thereby subject to a compressive force which causes the anchor portion 44 to deploy i.e. as the ribs 46 of the outer tube 22 fold radially outward (FIG. 12). Once the anchor portion 44 deploys, it engages the inner surface of the bone (i.e. the outer wall of the IM cavity) in the distal bone segment. Further turning of the compression nut 26 causes the engaged distal bone segment 74 to be pulled against the proximal bone segment 72 thereby securing the fracture site under a compressive force. In the alternative embodiment of the invention having an inner tube 21 (FIG. 4) disposed over the guide wire 16, the inner tube 21 can have a length relative to the length of the outer tube adapted so that the inner tube abuts the bone interface nut when an optimal anchor deployment condition is reached or to stop excessive advancement of the compression nut 26. In another alternative embodiment, the threaded portion 17 of the guide wire 16 extends only long enough along the guide wire 16 to allow optimal advancement of the compression nut 26 and thereby cause optimal engagement of the anchor portion 44. In an alternative method of installing the apparatus according to the present invention, an external reduction device is used to hold bone segments in place while the IM device 10 is installed. As shown in FIG. 14, the external fixation device includes a pair of telescoping tubes 102, 104 and a pin 106, 108 extending from the end of each telescoping tube 102, 104 into a respective bone segment. The pins 106, 108 are installed in holes drilled in each bone segment using fluoroscopic imaging as known in the art. An adjustment nut 110 causes the telescoping tubes 102, 104 to translate toward each other causing a compressive force between the bone segments. The external reduction apparatus 100 is left in place during installation of the IM bone fixation apparatus 10 of the invention and removed once the IM bone fixation apparatus 10 is in place. In embodiments of the invention intended for use in to repair curved bones, it should be understood by persons skilled in the art that the guide wire 16, inner tube 21, and outer tube 22 should have sufficient flexibility to allow each of these components to be installed sequentially in the IM space the curved bones. Once installed the combined strength and rigidity of these components provide the structure necessary for maintaining compression and providing strength to the bone under repair. In an alternative embodiment of the invention shown in FIG. 15, one or more semi-annular 120 cuts are provided in the outer tube 22 to increase flexibility for installation in the IM space curved bones. Such semi-annular cuts 120 increase flexibility in the outer tube 22 while maintaining strength in compression that is necessary to cause deployment of the anchor portion 44. Persons skilled in the art should appreciate that various similar structures can be substituted for the semi-annular cuts 120 according to the alternative embodiment within the scope of the present invention. It is completed in the practice of this invention that, in particular embodiments, the devices of this invention will be coated, in whole or in part, with bioactive material. As used herein bioactive material shall be broadly construed to include, without limitation, immunomodulators such as a cyclosporine, anti infectives such as antiviral or antibiotic compounds, angiogenic or antiangiogenic compounds, growth factors, antineoplastics compounds, compounds to encourage or prevent the adherence (or infiltration) of the device to the surrounding tissue, and other therapeutic agents. Further included are coatings to improve detection of the device such as radiopaque coatings and contrast media. Further contemplated are biodegradable coatings and coatings which may be impregnated with bioactive agents. While the invention has been described with reference to an exemplary embodiment, it should be understood by those skilled in the art that various changes, omissions and/or additions may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. The teaching of all references cited herein are incorporated herein by reference. | <SOH> BACKGROUND OF THE INVENTION <EOH>Various methods and apparatus have long been used for positioning, stabilizing and supporting bone segments to repair bone fractures in humans and animals. Simple external apparatus such as slings and splints are well known and are still used alone or in combination with invasive apparatus to repair broken bones. Slings are used alone in certain circumstances where use of invasive apparatus or implants presents an unacceptable risk of injury to a patient. For example, slings are often used without any invasive apparatus to repair a fractured clavicle because implantation of known invasive bone repair apparatus to repair a fractured clavicle can risk life threatening damage to the patient's subclavian artery or damage to other vessels, nerves, nerve bundles, vital organs or surrounding tissues. Since invasive repair of a fractured clavicle presents medical risk, patients having a fractured clavicle often forgo the benefits offered by various invasive apparatus and implants. Such benefits which include improved bone segment positioning, stabilizing and support promote more rapid recovery and reduce patient discomfort. Further, use of slings alone often allows misaligned bone segments to heal such that a visibly conspicuous deformation or a weak area remains which is susceptible to re-injury. Accordingly, it would be advantageous to provide a clavicle repair apparatus with reduced risk of injury to the patient. Known invasive apparatus for bone segment repair include various configurations of bone fracture reduction rods, orthopedic screws, intramedullary nails, intramedullary screws and the like. For example, U.S. Pat. No. 6,338,732 to Yang discloses an in-marrow nail structure having two threaded ends for drilling and engaging fractured bone segments. A nut is screwed over a threaded proximal portion of the structure to apply compressive force to the bone segments. The apparatus disclosed in Yang and similar devices involve installing a drilling tip within the intramedullary cavity. These devices typically incorporate threads having a cutting edge in at least a distal portion whereby drilling is performed by rotating the devices around their longitudinal axis. Accordingly, such devices are typically unsuitable for implantation in curved bone segments. Such devices also present a high risk of drilling through a bone segment into surrounding tissue, and are therefore not well suited for use in repairing a fractured clavicle. It would be desirable to provide an intramedullary apparatus that is suitable for use in curved bone segments without presenting a high risk of damaging surrounding tissue. In addition to providing a drilling capability for implanting an intramedullary device, the threaded distal portion of some known devices serves as an anchor which secures the distal portion of the device to a distal bone segment. Bone segments are held together by also providing a compressing portion which engages the proximal bone segment and travels toward the anchored distal portion. In another type of known intramedullary support apparatus, an expandable anchor portion is provided for engaging the distal bone segment. For example, U.S. Pat. Nos. 3,779,239; 3,760,802 and 4,227,518 disclose particular intramedullary retraction nails that include an expansion element in their distal portion. The expansion elements serves as an anchor in a distal bone segment. The aforementioned devices are generally directed toward a rod disposed with a tubular portion. Relative linear motion between the rod and the tubular portion, such as by threading the rod to the tubular portion, causes actuation of the expansion element to engage the bone lining in the distal portion. A bolt head and or nut and washer are installed over or incorporated with the proximal portion of the rod which protrudes from a hole drilled in the proximal bone segment. In the apparatus disclosed in U.S. Pat. Nos. 3,779,239 and 3,760,802 the central rod is curved to correspond with the curvature of the bone under repair. Installation of a rod within the intramedullary cavity can increase the risk of damage to the bone lining, and can be difficult to perform on curved bones such as the clavicle. Furthermore, apparatus heretofore known that are adapted for providing a distal anchor portion are not adapted for aligning a displaced fracture. Insertion of such devices to a misaligned fracture can cause increased separation of bone segments and possibly damage surrounding tissue. The rod's rigidity can also prevent it from centering radially when the expandable anchor portion is deployed. Such devices can therefore allow a bone to heal in a misaligned or overlapped state which can be weak or appear deformed. It would therefore be desirable to provide a intramedullary support device for use on curved bone segments that does not include a rigid internal rod portion, and which is self centering and adapted to align bone segments at a displaced fracture site. Known IM fixation devices having an expandable anchor portion are typically constructed with a number of separate moving components. The number of moving components can make such devices expensive and susceptible to malfunction. It would be desirable to provide an IM fixation device having an expandable anchor portion which does not require a large number of separate components. The proximal portion of known IM fixation devices is often movably disposed within the IM region of the proximal portion of a fractured clavicle bone. Such proximal portions of the device protrude from the posterior lateral end of the clavicle bone. A stabilizing nut is typically rotated to engage the threaded portion of the IM fixation device, thus causing the stabilizing nut to partially traverse the threaded portion of the IM fixation device. As the stabilizing nut traverses the threaded portion, the stabilizing nut pushes the proximal portion of the fractured clavicle bone toward the distal portion of the fractured clavicle bone. The stabilizing nut is rotated until the distal and proximal portions of the fractured clavicle bone contact each other, such that the fractured ends of the clavicle bone remain in contact with each other to allow for the accelerated healing of the clavicle fracture. Several heretofore known IM fixation devices include portions that prominently protrude from the proximal lateral end of the clavicle bone. Even small movement of such devices can causes extreme pain to a patient. It would therefore be desirable to provide an intramedullary fixation device that does not prominently protrude externally from the bone. Installation of some known intramedullary support devices involves invasive surgery wherein a cut-down must be performed at the fracture site. Such surgical installations increase the risk of infection, lengthen the recovery period, and often leave large unsightly scars. It would therefore be desirable to provide a method and apparatus for repairing fractured bones which is minimally invasive and which does not require a surgical cut-down at the fracture site. Many known intramedullary support devices are not fixed within the intramedullary space and can therefore suffer from migration within the intramedullary space. It has been known for intramedullary devices or components thereof to migrate such that they pierce a patient's surrounding tissue, skin, or vital organs. It would therefore be desirable to provide an intramedullary support device that does not suffer from migration. Many heretofore known intramedullary fixation devices are difficult to remove after a patient's fractured bone has healed. It would therefore be desirable to provide an intramedullary support device that is more easily removed from the bone after a fracture has healed. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a method and apparatus for minimally invasive fixation and repair of fractured long bones. The term “long bone” is used generally throughout the present specification and is meant to include any human or animal bone having sufficient intramedullary space for installation of the various embodiments of the invention described below. For example, various embodiments of the invention are described with respect to repair of a fractured collar bone in humans. It should be understood that the invention also includes a method and apparatus for repairing various other bones in humans in animals such as bones in the upper and lower extremities as well as smaller bones, including bones in human hands and fingers. According to an illustrative embodiment of the present invention, an opening is made into the intramedullary cavity toward a proximal end of a proximal bone segment. A guide wire is inserted through the opening and pushed through the intramedullary cavity of a proximal bone segment, across the fracture site and into the intramedullary cavity of a distal bone segment. A dilator having longitudinal through-hole and a tapered leading surface is inserted over the guide wire and pushed through the intramedullary cavity into the distal bone segment to a stop at the distal end of the guide wire. The tapered leading surface of the dilator is adapted to aid in the alignment of bone segments as it is pushed across the fracture site. A flexible tube having a radially expandable distal portion is then pushed over the guide wire into the distal bone segment and against the dilator. The expandable distal portion of the tube is deployed by compressing the flexible tube between its proximal end and the dilator. Compression of the flexible tube can be performed by threading a compression nut onto the proximal end of the guide wire. The distal stop on the guide wire prevents the dilator and flexible tube from moving further distally so that compression is applied to the flexible tube between the dilator and the compression nut. The compression nut and/or a washer disposed with the compression nut are adapted to engage the proximal bone segment so that the proximal and distal bone segments are pulled together. One embodiment of the present invention provides a bone segment positioning apparatus including a guide wire having a proximal end and a distal end. A distal stop is disposed on the guide wire about adjacent to the guide wire distal end. A proximal stop disposed on the guide wire about adjacent to the guide wire proximal end. A tube is disposed over the guide wire. The tube has a sidewall including a radially expandable anchor portion adapted for radial expansion upon compression of the tube between the distal stop and the proximal stop. At least one embodiment also includes a dilator having a tapered distal surface, an at least partially transverse proximal surface and a tubular inner surface defining a longitudinal through hole. The dilator is disposable on the guide wire wherein the guide wire extends through the through hole. The at least partially transverse proximal surface serves as the distal stop. In a particular embodiment, the at least partially transverse proximal surface can also be countersunk to accept the tube. The tapered distal surface can include means to prevent rotation of the dilator relative to the guide wire. Such means can be manifest, for example in a hexagonal depression in the tapered surface that mates with a hexagonal anti-rotation feature fixed to the guide wire. For example in one embodiment, the guide wire includes a spherical distal tip having a diameter greater than the diameter of the longitudinal through hole. The means to prevent rotation in this embodiment include a polygonal mating surface of the tapered surface adapted to fit an opposite gendered polygonal mating surface of the spherical distal tip. Persons having ordinary skill in the art should appreciate that a large number of anti-rotation features such as key/slot features, interference fits, wedges and the like could be substituted as anti-rotation means within the scope of the present invention. In one embodiment, the tube and guide wire are flexible. The proximal stop is formed as a distal surface of a compression fastener over the proximal end of the guide wire. The compression fastener comprises at least one nut threaded onto the proximal end of the guide wire. The radially expandable anchor portion includes a plurality of rib portions formed between a plurality of longitudinal slots disposed through the sidewall. The radially expandable anchor portion is disposed toward the distal end for engagement with a distal bone segment. In an illustrative embodiment, the rib portions include at least one reduced section formed in a central portion of each rib segment. The at least one reduced section can include a crease formed transversely across the central portion of each rib segment. Alternatively the at least one reduced section comprises a narrowed section of each rib segment. The at least one reduced section could also be creased and narrowed, for example. In a particular embodiment, the plurality of rib portions comprise at least two evenly spaced rib portions. The radially expandable anchor portion is also adapted to collapse upon relaxation of compression forces between distal and proximal segments of the tube. In another embodiment, the radially expandable anchor portion is adapted to collapse upon application of tension between distal and proximal segments of the tube. In another embodiment, the invention provides a method for aligning fractured bone segments. The method includes installing a tube in an intramedullary space spanning a fracture, anchoring a portion of the tube to a first side of the fracture, and compressing the tube to radially expand an expandable anchor portion of the tube on a second side of the fracture. In one embodiment, the method also includes installing a guide wire in the intramedullary space spanning the fracture. The tube is installed over the guide wire and compressed between stops on the guide wire. Anchoring a portion of the tube to a first side of the fracture can be performed, for example, by installing an anchor nut which engages the bone segment over a proximal end of the guide wire. The method can also include installing a tapered dilator over the guide wire prior to installing the tube over the guide wire. The dilator includes a transverse portion which serves as one of the stops. In the illustrative embodiment of the invention, the method also includes drilling into the intramedullary space in a proximal bone segment; and reaming the intramedullary space. The method can also include releasing compression on the flexible tube to allow the expandable anchor portion to retract for removal of the tube and guide wire upon healing of the bone segments. Advantages of the invention include provision of a bone segment positioning device and methodology that involves a safer, minimally invasive surgical procedure which allows for substantially less pain and discomfort for a patient. Further advantages of the invention include the ability to repair fractured bones without the need for “cut-down” at the fracture site, thus greatly reducing or eliminating any nerve and blood vessel disturbance and risk of infection. An additional advantage of the invention is that the bone segment positioning device is easily removable and malleable. The malleability of the device adds an extra degree of safety because the device will bend rather than applying potentially damaging lateral pressures in the IM cavity. The present invention overcomes the deficiencies of the prior art by providing a clavicle repair apparatus with reduced risk of injury to the subclavian artery. An intramedullary apparatus is provided that is suitable for use in curved bone segments without presenting a high risk of damaging surrounding tissue. The various embodiments of the present invention also provide an intramedullary support device for use on curved bone segments that does not include a rigid internal rod portion, and which is self centering and adapted to align bone segments at a displaced fracture site. Further, the present invention provides an IM fixation device having an expandable anchor portion which does not require a large number of separate components and does not prominently protrude externally from the bone. The various embodiments of the present invention also provide a method and apparatus for repairing fractured bones which is minimally invasive and which does not require a surgical cut-down at the fracture site | 20040329 | 20091215 | 20050929 | 96318.0 | 0 | ARAJ, MICHAEL J | ORTHOPEDIC INTRAMEDULLARY FIXATION SYSTEM | SMALL | 0 | ACCEPTED | 2,004 |
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10,811,849 | ACCEPTED | Apparatus and method for controlling CPU speed transition | An apparatus and method for controlling CPU speed transition can use an SMI (System Management Interrupt) signal to perform speed transition of a CPU of a computer such as a notebook computer. However, if the bus master device is in the active state, a control operation needed for CPU speed transition is cancelled at the same time an event signal (e.g., a watchdog SMI or an embedded controller SMI) is created at prescribed intervals and the bus mater device active state is accordingly re-checked. Therefore, when the bus master device is in the active state, the control operation for CPU speed transition is cancelled to prevent the computer from hanging up, and the CPU speed transition control operation is periodically retried to increase a likelihood of a normal CPU speed transition or the normal CPU speed transition can be established. | 1. A method for controlling CPU speed transition, comprising: receiving a System Management Interrupt (SMI) signal; determining whether a bus master device is in an active state when the SMI signal is for performing CPU speed transition; and canceling the CPU speed transition operation when the bus master device is in the active state and generating at prescribed intervals a retry SMI signal. 2. The method of claim 1, comprising performing the CPU speed transition operation when the bus master device is not in the active state. 3. The method of claim 1, wherein the retry SMI signal generated at prescribed intervals is one of a watchdog timer SMI signal and an embedded control SMI signal to retry the CPU speed transition operation. 4. The method of claim 3, wherein the determining comprises: disabling occurrences of additional watchdog timer SMI signals when the received SMI signal is the watchdog timer SMI signal to retry the CPU transition operation; and re-determining whether the bus master device is in the active state. 5. The method of claim 3, wherein the determining comprises: disabling occurrence of additional embedded controller SMI signals when the received SMI signal is an embedded controller SMI signal to retry the CPU speed transition operation; and re-determining whether the bus master device is in the active state. 6. The method of claim 3, wherein the determining comprises: performing a prescribed operation corresponding to the received SMI signal when the received SMI signal is not an SMI signal for CPU speed transition, the watchdog timer SMI signal to retry the CPU speed transition operation or the embedded controller SMI to retry the CPU speed transition operation. 7. The method of claim 1, wherein the SMI signals are at least one of a hardware generated signal and an application program generated signal. 8. A portable computer, comprising: a CPU configured to operate using at least two speeds; a controller configured to perform a prescribed operation to transition between the at least two speeds of the CPU; interrupt occurrance reason recognition means for recognizing an occurrence reason of an interrupt signal; active state checking means for checking an active state of a predetermined device; and interrupt generating means for creating a second interrupt signal to retry the prescribed operation for the CPU speed transition when the interrupt occurrence reason recognition means determines that a first interrupt signal is created for the CPU speed transition and the active state checking means determines that the predetermined device is in the active state. 9. The portable computer of claim 8, wherein the interrupt signal for the CPU speed transition is responsive to a change of CPU use amount, switching between AC adapter and battery power sources, reduction of battery lifetime, runtime setup of a user and temperature variation. 10. The portable computer of claim 8, wherein the interrupt generating means creates the second interrupt signal using a predetermined timer contained in the system. 11. The portable computer of claim 10, wherein the predetermined timer contained in the system is a watchdog timer or an inner timer of an embedded controller. 12. The portable computer of claim 10, wherein the second interrupt signal is created at intervals of a predetermined time determined by a system BIOS. 13. The portable computer of claim 8, wherein the predetermined device is a bus master device. 14. The portable computer of claim 8, wherein the second interrupt is repeatedly generated until the CPU transition is performed, and wherein the portable computer is a notebook computer. 15. An apparatus, comprising: an interrupt receiver configured to receive interrupt signals; and an interrupt generator coupled to the interrupt receiver and configured to generate a second interrupt signal to retry a prescribed operation needed for CPU speed transition when a first interrupt signal for the CPU speed transition is received and a bus master device is in an active state. 16. The apparatus of claim 15, wherein the interrupt generator creates the second interrupt signal using a predetermined timer contained in the system. 17. The apparatus of claim 16, wherein the predetermined timer contained in the system is at least one of a watchdog timer and an inner timer of an embedded controller. 18. The apparatus of claim 16, wherein the second interrupt signal is created at intervals of a predetermined time determined by a system BIOS. 19. The apparatus of claim 15, wherein the apparatus is in a notebook computer. 20. The apparatus of claim 15, wherein the interrupt signals are one of hardware interrupts and software interrupts. 21. An article including a machine-readable storage medium containing instructions for controlling CPU speed transition in a computer system, said instructions, when executed in the computer system, causing the computer system to: receive an System Management Interrupt (SMI) signal; determine whether a bus master device is in an active state when the SMI signal is a first SMI CPU speed transition signal; and cancel the CPU speed transition operation when the bus master device is in the active state and generate at predetermined intervals an event. 22. The article of claim 21, wherein the event is a second SMI CPU speed transition signal. 23. The article of claim 22, wherein the event is one of a hardware interrupt and a software interrupt. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for controlling CPU speed transition, and more particularly to a CPU speed transition. 2. Background of the Related Art FIG. 1 is a flow chart illustrating a related art CPU speed transition control method applied to a computer system. For example, if an SMI (System Management Interrupt) signal occurs in a notebook computer at step S10, a system BIOS of the notebook computer recognizes why the SMI signal has occurred at step S11. Unless the reason for the SMI signal occurrence is to perform a transition of Geyserville CPU speed at step S12, the system BIOS processes a prescribed operation corresponding to the SMI signal at step S13. Otherwise, if the SMI signal has occurred to perform Geyserville CPU speed transition either from high speed to low speed or from low speed to high speed, it is determined whether a bus master device in the notebook computer is in an active state at step S14. If the bus master device is not in the active state, the system BIOS sets a transition flag to a first prescribed value indicative of transition success at step S15, and increases or decreases the Geyserville CPU speed at step S16. The system BIOS determines whether the Geyserville CPU speed transition is normally executed at step S17. In this case, if the Geyserville CPU speed transition is abnormally executed, the system BIOS sets a transition flag to a second prescribed value indicative of transition failure at step S18, and terminates the SMI service operation at step S19. If it is determined that the bus master device is in the active state at step S14, the system BIOS sets the transition flag to the second prescribed value indicative of transition failure without performing the Geyserville CPU speed transition at step S18. Then, the system BIOS terminates the SMI service operation at step S19 so that it can prevent a computer system from hanging up. Thereafter, the system BIOS repeats the above-described steps until receiving a system-off command at step S20. The reason why the computer system hangs up is as follows. When the system BIOS performs CPU speed transition when the bus master device (from among several system devices) is in an active state, the CPU is not in a normal mode while performing the CPU speed transition, and the system BIOS cannot continuously perform the bus master device's current operations any longer. Accordingly, the computer system hang up is avoided by preventing the CPU speed transition when the bus master device is active. As described above, the related art apparatus and method for controlling CPU speed transition have various disadvantages. For example, if the bus master device is in the active state and the system BIOS immediately terminates the SMI service without performing the CPU speed transition, the computer system does not hang up, however, the SMI service is terminated because of transition failure. Therefore, it is difficult or impossible for the system BIOS to normally perform the CPU speed transition. The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background. SUMMARY OF THE INVENTION An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter. Another object of the present invention is to provide an apparatus and method for controlling CPU speed transition between high and low speeds. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state, but repeatedly generates an event needed for the CPU speed transition. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state, but repeatedly generates an event needed for the CPU speed transition, for example, a watchdog timer SMI and an embedded controller SMI, at regular time intervals to result in normal CPU speed transition. In accordance with one aspect of the present invention, at least the above and other objects can be accomplished in a whole or in part by providing a method for controlling CPU speed transition that includes receiving a System Management Interrupt (SMI) signal, determining whether a bus master device is in an active state when the SMI signal is for performing CPU speed transition and canceling the CPU speed transition operation when the bus master device is in the active state and generating at prescribed intervals a retry SMI signal. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided a portable computer that includes a CPU configured to operate using at least two speeds, a controller configured to perform a prescribed operation to transition between the at least two speeds of the CPU, interrupt occurrance reason recognition unit for recognizing an occurrence reason of an interrupt signal, active state checking unit for checking an active state of a predetermined device and interrupt generating unit for creating a second interrupt signal to retry the prescribed operation for the CPU speed transition when the interrupt occurrence reason recognition unit determines that a first interrupt signal is created for the CPU speed transition and the active state checking unit determines that the predetermined device is in the active state. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided an apparatus that includes an interrupt receiver configured to receive interrupt signals and an interrupt generator coupled to the interrupt receiver and configured to generate a second interrupt signal to retry a prescribed operation needed for CPU speed transition when a first interrupt signal for the CPU speed transition is received and a bus master device is in an active state. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided an article including a machine-readable storage medium containing instructions for controlling CPU speed transition in a computer system, said instructions, when executed in the computer system, causing the computer system to receive an System Management Interrupt (SMI) signal, determine whether a bus master device is in an active state when the SMI signal is a first SMI CPU speed transition signal and cancel the CPU speed transition operation when the bus master device is in the active state and generate at predetermined intervals an event. Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: FIG. 1 is a flow chart illustrating a related art CPU speed transition control method for a computer system; FIG. 2 is a block diagram illustrating a preferred embodiment of a computer system including a CPU speed transition control apparatus in accordance with the present invention; FIGS. 3 and 4 are flow charts illustrating a preferred embodiment of CPU speed transition control methods in accordance with the present invention; and FIGS. 5 and 6 are flow charts illustrating another preferred embodiment of CPU speed transition control methods in accordance with the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 2 is a block diagram illustrating a computer system to which embodiments of CPU speed transition control apparatus and methods in accordance with the present invention can be applied. For example, a computer system such as a notebook computer can include a CPU 10, an embedded controller device 20, a bus master device 30, a PCI (Peripheral Component Interconnect) bridge 40, a system ROM 50, and a system memory 60. The PCI bridge 40 can include Geyserville logic 400, a watchdog timer 410, SMI (System Management Interrupt) logic 420, an ISA/LPC logic 430, and a PCI/AGP interface 440. The system memory 60 using DRAM can store a user program, etc. The CPU 10 may be one of a variety of CPUs where Intel Corporation's SpeedStep or Geyserville technology is supported. For example, the CPU 10 may be a mobile Intel Pentium 4 processor, combined with Intel SpeedStep Technology (also called Geyserville technology) or its similar equivalents, such that it can support Enhanced Intel SpeedStep Technology. In this case, it should be noted that the SpeedStep technology is equal to that of the Geyserville technology. The SpeedStep technology enables the CPU 10 to perform an automatic switching function between two core frequencies according to CPU demand. For example, the CPU demand may be CPU load information. The switching function of the operation frequency of the CPU 10 can be executed without either resetting the CPU 10 or changing a system bus frequency. The Mobile Intel Pentium 4 processor operates in two modes, e.g., a maximum performance mode and a battery optimized mode. The Mobile Intel Pentium 4 processor may further support at least one mode other than the two modes. GV signals shown in FIG. 2 are composed of a variety of signals, for example, G_GMI, G_NMI, GM_INIT, G_INTR, G_STPCL#, and LO/HI#, etc. In response to individual signals, the CPU 10 can execute a transition of its own operation frequency and applied voltage. The reception voltage of the CPU 10 generated from a voltage regulator 70 can be controlled by VR_LO/HI# and Vgate signals received from the Geyserville logic 400. After Microsoft Windows XP has been installed in a computer system such as a notebook computer and a power-supply management item contained in a Windows' Control Panel has been set to an adaptive mode, if a power-supply source is changed in the direction either from an AC adapter to a battery or from the battery to the AC adapter, and if either a battery lifetime or an CPU use information changes, the Geyserville logic 400 can automatically perform CPU speed transition either in the direction from high speed to low speed, or in the other direction from low speed to high speed. The transition operation may also be performed by Microsoft Windows XP. Windows XP can execute a unique built-in support program needed for Processor Performance Control. The unique built-in support program can be a Native Processor Performance Control program. The Native Processor Performance Control program may implement a variety of technologies such as an Enhanced Intel SpeedStep Technology, etc., therein. The unique built-in support program needed for Processor Performance Control in Windows XP can be composed of two components, e.g., a Processor Performance Control component and a Processor Performance Control Policy. The Processor Performance Control component is a prescribed function needed for changing a performance state. Windows XP can execute the Processor Performance Control function using either the Legacy SMI Interface prescribed by Intel Corporation or the Processor Objects prescribed in the Advanced Configuration and Power Interface (ACPI) standard. In this case, the Legacy SMI Interface and the Processor Objects are associated with the above-described SpeedStep technology. The Processor Performance Control Policy component is preferably the set of behavior rules used to determine the appropriate performance state to be used. Windows XP has associated the Processor Performance Control Policy with a prescribed power scheme, and has defined four control policies needed for the Processor Performance Control. These four Control policies are composed of a constant mode for enabling a processor to always run in a lowest performance state, an adaptive mode for enabling the processor to select a performance state on the basis of CPU demand, a degrade mode for enabling the processor to start in the lowest performance state and use a linear performance reduction function (i.e., a stop clock throttling function) in proportion to a battery discharge time, and a none-mode for enabling the processor to always run in a highest performance state. However, the present invention is not intended to be so limited. For example, the number of the above control policies may also be increased or decreased on the basis of another reference. The SMI signal can be created as an event needed for CPU operation frequency transition based on the Intel SpeedStep Technology. In this case, there can be a variety of items associated with the SMI signal occurrence, for example, CPU use amount, temperature (e.g., thermal conditions), and battery life, etc. Therefore, in the case where the CPU 10 is a processor where more than two frequencies are supported and predetermined conditions for one of the aforementioned items are satisfied, preferably the CPU 10 can automatically perform a transition of its own operation frequency. It should be noted that the above-described items may also be changed to another item, and the predetermined conditions for corresponding items may be deleted or further added if needed. An exemplary transition CPU speed based on the CPU use amount will now be described. In the case of using MS-Word, the percentage of CPU use is preferably in the range from 20% to 40%. In the case of reproducing a DVD (Digital Versatile Disc), the percentage of CPU use is preferably substantially 100%. Therefore, according to the CPU workload, the CPU speed transition can be automatically or directly executed using Windows XP. For example, if the percentage of the CPU use is equal to or higher than 95%, a CPU operation frequency transition to a highest or the Maximum Performance Mode can be automatically performed. Otherwise, if the percentage of CPU use is equal to or lower than 75%, a CPU operation frequency transition to the Battery Optimized Mode can be automatically performed. In the meantime, if the percentage of CPU use is 95% in a specific CPU capable of supporting more than four frequency modes, the CPU speed can be automatically switched to the highest operation frequency. If the percentage of CPU use is in the range from 75% to 94% in the same CPU capable of supporting more than four frequency modes, the CPU speed can be automatically switched to the second-highest operation frequency. If the percentage of CPU use is in the range from 40% to 74% in the same CPU capable of supporting more than four frequency modes, the CPU speed can be automatically switched to the third-highest operation frequency. If the percentage of CPU use is lower than 40% in the same CPU capable of supporting more than four frequency modes, the CPU speed is automatically switched to the lowest operation frequency. For example, the SMI handler denoted by “SMI Service #2” contained in the system ROM shown in FIG. 2 can automatically perform the CPU speed transition according to the CPU use information, for example, as described above. An exemplary CPU speed transition based on the thermal conditions will now be described. For example, if the CPU or peripheral chipsets overheat because of an application load factor, the thermal event SMI signal occurs, and the CPU's operation frequency or reception voltage can be automatically regulated to maintain the temperature of the CPU at a temperature below a predetermined temperature. If the CPU temperature increases, the SMI handler denoted by “SMI Service #2” in the system ROM 50 can perform a transition from a highest or maximum performance mode to a lower performance or the battery optimized mode. However, if the CPU temperature is not lower than a predetermined temperature, e.g., if the CPU continues to overheat after the CPU has entered the battery optimized mode, the system BIOS or Windows XP may perform a throttling mode to cool the CPU 10. The throttling mode can enable a clock signal applied to the CPU to be stopped at a predetermined rate while the CPU is continuously operated at a fixed frequency (i.e., a high or low frequency) in such a way that the CPU speed is controlled. This throttling mode is different from the SpeedStep transition method. Further, provided that the CPU supports more than four operation frequencies, the system BIOS may gradually control the operation frequencies of the CPU 10 until the CPU 10's temperature reaches a desired temperature, instead of performing a transition to the throttle mode. For example, if the CPU temperature is equal to or higher than 100° C. on the assumption that a desired CPU temperature is 70° C., the CPU speed can be transitioned from the highest operation frequency mode to the second-highest operation frequency mode using the thermal event SMI signal. If the CPU temperature is in the range from 90° C. to 99° C. on the assumption that the desired CPU temperature is 70° C., the CPU speed can be transitioned to the third-highest operation frequency mode. If the CPU temperature is in the range from 71° C. to 89° C. on the assumption that the desired CPU temperature is 70° C., the CPU speed is automatically transitioned to the lowest operation frequency mode. An exemplary CPU speed transition based on battery life will now be described. For example, if a user sets a power management item for example in Windows XP to the degrade mode, the CPU can first start in a lowest performance state, and then perform the stop clock throttling function for executing linear performance reduction in proportion to a battery discharge time using or responsive to the SMI signal. In this case, a CPU supporting more than two operation frequencies can automatically or directly control transition movements between the more than two operation frequencies based upon the battery discharge time. The SMI signal has been created due to a variety of reasons, for example, a change of CPU use amount, switching between AC adapter and battery power sources, reduction of battery lifetime, and temperature variation. However, the present invention is not intended to be so limited. Further, even in the case where the user sets the power management item in Windows XP to either one of constant mode, none mode, adaptive mode, and degrade mode as a runtime mode, the SMI signal can also be created. In addition, the above described reasons of SMI signal occurrence may be deleted or new reasons may be added. If necessary, the SMI signal occurrence conditions may be changed to another conditions. Further, in preferred embodiments according to the present invention, SMI signal is intended to include at least both types of hardware generated and software generated events or interrupts. Accordingly, as described, signals are intended to include both hardware signals, application generated signals and software signals, packets or registers. In the computer system shown in FIG. 2, the embedded controller device 20, the PCI bridge 40, Windows XP or the like can check the above created events, and thereby create an SMI signal needed or used for the CPU speed transition. The SMI logic 420 preferably executes an SMI service operation corresponding to the above-created SMI signal, and operations of the SMI logic 420 will now be described. Embodiments of CPU speed transition control methods according to the present invention can be applied to a computer system such as a notebook computer having the above-described configuration shown in FIG. 2. Provided that the bus master device is in an active state, SMI control such as the SMI logic 420 can cancel a prescribed control operation needed for CPU speed transition, and control at a designated time creating an SMI signal (e.g., by a watchdog timer SMI signal or an embedded controller SMI signal) needed for CPU speed transition preferably at regular time intervals. The SMI logic 420 can re-check whether the bus master device is in the active state (e.g., by referring to the periodically created watchdog timer SMI or embedded controller SMI signal). If the bus master device is not in the active state, a CPU speed transition operation can then be executed. FIGS. 3 and 4 are flow charts illustrating CPU speed transition control methods in accordance with an embodiment of the present invention. The embodiment of the CPU speed transition control method of FIGS. 3-4 can be applied to and will be described using the portable computer of FIG. 2. However, the present invention is not intended to be so limited. As shown in FIG. 3, after a process starts if the SMI signal is created at step S10, the system BIOS in the notebook computer of FIG. 2 can recognize why the SMI signal is created at step S11 (e.g., the reason for SMI signal occurrence). If it is determined that the SMI signal is created for CPU 10 speed transition at step S12, the system BIOS can determine whether the bus master device 30 is in an active state at step S14. The SMI signal may be created for a variety of reasons, for example, a change of CPU use amount, switching between AC adapter and battery power sources, reduction of battery lifetime, temperature variation and the like. Further, the SMI signal can also be created where the user sets the power management item in Windows XP to either one of a constant mode, none mode, adaptive mode, and degrade mode as a runtime mode. In addition, the reasons described above for the SMI signal occurrence may also be deleted or new reasons may be added. If necessary, the SMI signal occurrence conditions may also be changed to another conditions. If it is determined in step S12 that the SMI signal is created for CPU 10 speed transition, the system BIOS can determine whether the bus master device 30 is in the active state, for example, by checking the result of monitoring an active state of individual system devices contained in the system using an arbiter of a bus controller (not shown) contained in the PCI bridge 40. If it is determined that the bus master device is not in the active state at step S14, the system BIOS can set a transition flag to a prescribed value indicative of transition success at step S15, and increase or decrease the CPU 10's speed at step S16. In this case, the CPU speed transition may also be executed using Native Processor Performance Control for Windows XP. Thereafter, the system BIOS can determine whether the CPU 10's speed control operation is normally executed at step S17. If the CPU 10's speed control operation has been abnormally executed, the system BIOS can set a transition flag to a prescribed value indicative of transition failure at step S18, and terminate the SMI service operation at step S19. The system BIOS can repeat the above-described steps until receiving a system-off command at step S20. If it is determined that the bus master device is in an active state at step S14, the system BIOS can disable a previously-setup watchdog timer (e.g., having a period of 2 msec) SMI at step S50, and can newly set a creation period of the SMI signal needed for CPU speed transition to a predetermined period (e.g., a period of 250 msec) at step S51. Typically, the watchdog timer is a timer for creating interrupt signals at intervals of a predetermined time (e.g., 2 msec). Therefore, the system BIOS can enable the watchdog timer for CPU speed transition at step S52 in order to create interrupt signals at intervals of a new predetermined time (e.g., 250 msec), and terminates the currently-executing SMI service at step S52. Thereafter, the watchdog timer SMI signal can be created at intervals of the above time of 250 msec, such that the SMI service operation is repeatedly executed. The system BIOS can recognize the reason for SMI occurrence at step S11. If it is determined in step S11 that the SMI signal is created from the newly-setup watchdog timer in order to perform CPU speed transition at step S12 and step S60, the system BIOS can disable the watchdog timer SMI at step S61, and perform successive operations needed to determine whether the bus master device is in the active state at step S14. If the SMI signal has no connection with the above SMI created from the watchdog timer needed for the CPU speed transition, the system BIOS preferably executes a corresponding SMI processing operation at step S13. In step S61, the watchdog timer and accordingly other interrupts (e.g., SMI) or operations by the watchdog timer are preferably disabled to prevent a computer system hang-up. In other words, the watchdog timer operations are suspended to reduce a possibility of multiple operations, which may not be accurately provided, during repeatedly attempting the CPU speed transition. In the meantime, if the bus master device is still in the active state after performing the step S61, the system BIOS can cancel the CPU 10's speed transition operation to prevent the computer system from hanging up, and control the watchdog timer to create SMI signals needed for a CPU speed transition retrial at intervals of a predetermined time at steps S50˜S52. Otherwise, if the bus master device is not in the active state after performing the step S61, the system BIOS can normally execute the CPU speed transition steps S15˜S18. Thereafter, the system BIOS terminates the SMI service operation at step S19, and can repeat the above-described successive steps until receiving a system-off command at step S20. In this case, as for the SMI signal having been created for CPU speed transition, the SMI handler contained in the system BIOS 50 preferably recognizes the reason for SMI occurrence, performs the SMI service #2 routine contained in the system ROM 50 shown in FIG. 2, or may jump to a prescribed routine stored in the system ROM 50 in association with the SMI service #1 routine contained in the SMI logic 420 of the PCI bridge 40 and may perform the jump routine. FIGS. 5 and 6 are flow charts illustrating CPU speed transition control methods in accordance with another embodiment of the present invention. The embodiment of the CPU speed transition control method of FIGS. 5-6 can be applied to and will be described using the portable computer of FIG. 2. As shown in FIGS. 5-6, if the PCI bridge 40 of FIG. 2 does not contain the above watchdog timer function, the system BIOS can perform the above-identified CPU speed transition operation using the SMI signal created from the embedded controller device 20. As shown in FIG. 5, after a process starts if the SMI signal is created at step S10, the system BIOS in the notebook computer can recognize the reason for SMI signal occurrence at step S11. If it is determined that the SMI signal is created for CPU 10's speed transition at step S12, the system BIOS can determine whether the bus master device 30 is in an active state at step S14. In this case, a method for determining whether the bus master device 30 is in the active state and the reason for SMI signal occurrence are preferably similar to the embodiment of FIGS. 3-4. If it is determined that the bus master device 30 is not in the active state at step S14, the system BIOS can set a transition flag to a prescribed value indicative of transition success at step S15, and increase or decrease the CPU 10's speed at step S16. Thereafter, the system BIOS can determine whether the CPU 10's speed control operation is normally executed at step S17. If the CPU 10's speed control operation has been abnormally executed, the system BIOS can set a transition flag to a prescribed value indicative of transition failure at step S18, and terminate the SMI service operation at step S19. The system BIOS can repeat the above-described steps until receiving a system-off command at step S20. If it is determined that the bus master device 30 is in an active state at step S14, the system BIOS can disable previously-setup embedded controller SMIs at step S70, and output a prescribed command for newly setting a creation period of the SMI signal needed for CPU speed transition to a predetermined period (e.g., a period of 250 msec) to the embedded controller device at step S71. In this case, the system BIOS can newly set a period of embedded controller SMI occurrence to the predetermined period (e.g., 250 msec) using an inner timer contained in the embedded controller device 20 shown in FIG. 2 at step S71. In order to create interrupt signals at intervals of the new predetermined time (e.g., 250 msec), the system BIOS can enable the embedded controller SMI signal needed for CPU speed transition at step S72, and also (e.g., preferably at the same time) terminate the currently-executing SMI service at step S19. Thereafter, the embedded control SMI signal can be created at intervals of the above predetermined time (e.g., 250 msec), such that the SMI service operation is repeatedly executed. If the embedded controller SMI signal is detected at step S80 as shown in FIG. 6, the system BIOS can disable the embedded controller SMI at step S81, and recognize the reason for the SMI signal occurrence at step S82. If it is determined that the embedded controller SMI signal is created for CPU speed transition at step S83, the system BIOS can repeatedly perform successive operations needed to determine whether the bus master device is in the active state at step S14. However, if the embedded controller SMI signal has no connection with the CPU speed transition, the system BIOS preferably executes a corresponding embedded controller SMI processing operation at step S84, and enables the embedded controller SMI at step S72. In step S81, the embedded controller and accordingly other interrupts (e.g., SMI) or operations by the embedded controller are preferably disabled to prevent a computer system hang-up. In other words, the embedded controller operations are suspended to reduce a possibility of multiple operations, which may not be accurately provided, during repeatedly attempting the CPU speed transition. If it is determined that the bus master device is in the active state at step S14, the system can BIOS cancel the CPU 10's speed transition operation to prevent the computer system from hanging up, and control the embedded controller to create SMI signals needed for a CPU speed transition retrial at intervals of a predetermined time at steps S70˜S72. Otherwise, if the bus master device is not in the active state, the system BIOS can normally execute the CPU speed transition steps S15˜S18. Thereafter, the system BIOS terminates the SMI service operation at step S19, and can repeat the above-described successive steps until receiving a system-off command at step S20. In a similar process to FIGS. 3 and 4 for the SMI signal having been created for CPU speed transition, the SMI handler contained in the system BIOS 50 preferably recognizes the reason for SMI occurrence, performs the SMI service #2 routine contained in the system ROM 50 shown in FIG. 2, or may jump to a prescribed routine stored in the system ROM 50 in association with the SMI services #1 routine contained in the SMI logic 420 of the PCI bridge 40 and may perform the jump routine. As described above, embodiments of an apparatus and method for controlling CPU speed transition according to the present invention have various advantages. Embodiments of an apparatus and method for controlling CPU speed transition can cancel a prescribed control operation needed for CPU speed transition if the bus master device is in an active state to reduce or prevent the computer system from hanging up. Further, embodiments can retry the CPU speed transition control operation, for example, at intervals of a predetermined time so that a normal CPU speed transition can be established. The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to an apparatus and method for controlling CPU speed transition, and more particularly to a CPU speed transition. 2. Background of the Related Art FIG. 1 is a flow chart illustrating a related art CPU speed transition control method applied to a computer system. For example, if an SMI (System Management Interrupt) signal occurs in a notebook computer at step S 10 , a system BIOS of the notebook computer recognizes why the SMI signal has occurred at step S 11 . Unless the reason for the SMI signal occurrence is to perform a transition of Geyserville CPU speed at step S 12 , the system BIOS processes a prescribed operation corresponding to the SMI signal at step S 13 . Otherwise, if the SMI signal has occurred to perform Geyserville CPU speed transition either from high speed to low speed or from low speed to high speed, it is determined whether a bus master device in the notebook computer is in an active state at step S 14 . If the bus master device is not in the active state, the system BIOS sets a transition flag to a first prescribed value indicative of transition success at step S 15 , and increases or decreases the Geyserville CPU speed at step S 16 . The system BIOS determines whether the Geyserville CPU speed transition is normally executed at step S 17 . In this case, if the Geyserville CPU speed transition is abnormally executed, the system BIOS sets a transition flag to a second prescribed value indicative of transition failure at step S 18 , and terminates the SMI service operation at step S 19 . If it is determined that the bus master device is in the active state at step S 14 , the system BIOS sets the transition flag to the second prescribed value indicative of transition failure without performing the Geyserville CPU speed transition at step S 18 . Then, the system BIOS terminates the SMI service operation at step S 19 so that it can prevent a computer system from hanging up. Thereafter, the system BIOS repeats the above-described steps until receiving a system-off command at step S 20 . The reason why the computer system hangs up is as follows. When the system BIOS performs CPU speed transition when the bus master device (from among several system devices) is in an active state, the CPU is not in a normal mode while performing the CPU speed transition, and the system BIOS cannot continuously perform the bus master device's current operations any longer. Accordingly, the computer system hang up is avoided by preventing the CPU speed transition when the bus master device is active. As described above, the related art apparatus and method for controlling CPU speed transition have various disadvantages. For example, if the bus master device is in the active state and the system BIOS immediately terminates the SMI service without performing the CPU speed transition, the computer system does not hang up, however, the SMI service is terminated because of transition failure. Therefore, it is difficult or impossible for the system BIOS to normally perform the CPU speed transition. The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background. | <SOH> SUMMARY OF THE INVENTION <EOH>An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter. Another object of the present invention is to provide an apparatus and method for controlling CPU speed transition between high and low speeds. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state, but repeatedly generates an event needed for the CPU speed transition. Another object of the present invention to provide an apparatus and method for controlling CPU speed transition, which terminates an SMI service without performing a control operation needed for CPU speed transition when a bus master device is in an active state, but repeatedly generates an event needed for the CPU speed transition, for example, a watchdog timer SMI and an embedded controller SMI, at regular time intervals to result in normal CPU speed transition. In accordance with one aspect of the present invention, at least the above and other objects can be accomplished in a whole or in part by providing a method for controlling CPU speed transition that includes receiving a System Management Interrupt (SMI) signal, determining whether a bus master device is in an active state when the SMI signal is for performing CPU speed transition and canceling the CPU speed transition operation when the bus master device is in the active state and generating at prescribed intervals a retry SMI signal. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided a portable computer that includes a CPU configured to operate using at least two speeds, a controller configured to perform a prescribed operation to transition between the at least two speeds of the CPU, interrupt occurrance reason recognition unit for recognizing an occurrence reason of an interrupt signal, active state checking unit for checking an active state of a predetermined device and interrupt generating unit for creating a second interrupt signal to retry the prescribed operation for the CPU speed transition when the interrupt occurrence reason recognition unit determines that a first interrupt signal is created for the CPU speed transition and the active state checking unit determines that the predetermined device is in the active state. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided an apparatus that includes an interrupt receiver configured to receive interrupt signals and an interrupt generator coupled to the interrupt receiver and configured to generate a second interrupt signal to retry a prescribed operation needed for CPU speed transition when a first interrupt signal for the CPU speed transition is received and a bus master device is in an active state. To further achieve the above objects and advantages in a whole or in part in accordance with another aspect of the present invention, there is provided an article including a machine-readable storage medium containing instructions for controlling CPU speed transition in a computer system, said instructions, when executed in the computer system, causing the computer system to receive an System Management Interrupt (SMI) signal, determine whether a bus master device is in an active state when the SMI signal is a first SMI CPU speed transition signal and cancel the CPU speed transition operation when the bus master device is in the active state and generate at predetermined intervals an event. Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims. | 20040330 | 20080415 | 20050120 | 65323.0 | 0 | BROWN, MICHAEL J | APPARATUS AND METHOD FOR CONTROLLING CPU SPEED TRANSITION | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,811,979 | ACCEPTED | Semiconductor device method for manufacturing the same, apparatus for forming film, and method for forming high-dielectric-constant film | A semiconductor device having a gate electrode on a silicon substrate via a gate insulating film is formed by laminating the gate insulating film with a silicon oxide film, formed on the silicon substrate, an Hf silicate film is formed on the silicon oxide film, and a nitrogen-containing Hf silicate film formed on the Hf silicate film, and containing Hf in a peak concentration in a range from one atomic % to thirty atomic %, and nitrogen in a peak concentration in a range from ten atomic % to thirty atomic %. | 1. A semiconductor device comprising: a substrate; a gate insulating film on said substrate, and including one of a nitrogen-containing metal silicate film and a nitrogen-containing metal aluminate film that contains a metal in a peak concentration in a range from one atomic % to thirty atomic % on the uppermost layer; and a gate electro on said gate insulating film. 2. A semiconductor device comprising: a substrate; a gate insulating film on said substrate, and including: a base interface layer on said substrate, a metal silicate film on said base interface layer, and containing a metal, oxygen, and silicon, and a nitrogen-containing metal silicate film that contains a metal, oxygen, silicon, and nitrogen; and a gate electrode on said gate insulating film, wherein said nitrogen-containing metal silicate film contains said metal in a peak concentration in a range from one atomic % to thirty atomic %. 3. The semiconductor device according to claim 2, wherein said metal silicate film contains said metal in a peak concentration in a range from five atomic % to forty atomic %. 4. The semiconductor device according to claim 1, wherein said nitrogen-containing metal silicate film contains said nitrogen in a peak concentration in a range from ten atomic % to thirty atomic %. 5. A method of manufacturing a semiconductor device comprising: forming a base interface layer on a substrate; forming a metal silicate film containing a metal in a peak concentration in a range from one atomic % to thirty atomic % on said base interface layer; forming a nitrogen-containing metal silicate film containing nitrogen in a peak concentration in a range from ten atomic % to thirty atomic % on said metal silicate film; and forming a gate electrode on said nitrogen-containing metal silicate film. 6. The method of manufacturing a semiconductor device according to claim 5, wherein forming said metal silicate film includes, repeatedly: forming a metal oxide film by supplying a metal-containing material, and then supplying an oxygen-based gas to said substrate; and forming a silicon oxide film by supplying a silicon-containing material, and then supplying an oxygen-based gas to said substrate; and forming said metal silicate film includes controlling the number of cycles of forming said metal oxide film and forming said silicon oxide film. 7. The method of manufacturing a semiconductor device according to claim 6, including repeatedly forming said metal oxide film by: supplying said metal-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 8. The method of manufacturing a semiconductor device according to claim 6, including repeatedly forming said silicon oxide film by: supplying said silicon-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 9. A method of manufacturing a semiconductor device comprising: forming a base interface layer on a substrate; forming a metal silicate film containing a metal in a peak concentration in a range from five atomic % to forty atomic % on said base interface layer; forming a nitrogen-containing metal silicate film containing a metal in a peak concentration in a range from one atomic % to thirty atomic % and nitrogen in a peak concentration in a range from ten atomic % to thirty atomic % on said metal silicate film; and forming a gate electrode on said nitrogen-containing metal silicate film. 10. The method of manufacturing a semiconductor device according to claim 9, wherein forming said metal silicate film includes, repeatedly: forming a metal oxide film by supplying a metal-containing material, and then supplying an oxygen-based gas to said substrate; and forming a silicon oxide film by supplying a silicon-containing material, and then supplying an oxygen-based gas to said substrate; and forming said metal silicate film includes controlling the number of cycles of forming said metal oxide film and forming said silicon oxide film. 11. The method of manufacturing a semiconductor device according to claim 10, including repeatedly forming said metal oxide film by: supplying said metal-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 12. The methods of manufacturing a semiconductor device according to claim 10, including repeatedly forming said silicon oxide film by: supplying said silicon-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 13. The methods of manufacturing a semiconductor device according to claim 9, wherein forming said nitrogen-containing metal silicate film comprises: forming a base metal silicate film containing a metal in a peak concentration in a range from one atomic % to thirty atomic %; and introducing nitrogen into said base metal silicate film in a peak concentration in a range from ten atomic % to thirty atomic % by nitriding said metal silicate film. 14. The method of manufacturing a semiconductor device according to claim 13, wherein forming a base metal silicate film includes: a first step for forming a metal oxide film by supplying a metal-containing material, and then supplying an oxygen-based gas onto said substrate; and a second step for forming silicon oxide film by supplying a silicon-containing material, and then supplying an oxygen-based gas onto said substrate; and controlling the number of cycles of forming said metal oxide film and forming said silicon oxide film to form said metal silicate film. 15. The method of manufacturing a semiconductor device according to claim 14, including repeatedly forming said metal oxide film by: supplying said metal-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 16. The method of manufacturing a semiconductor device according to claim 14, including repeatedly forming said silicon oxide film by: supplying said silicon-containing material to said substrate; supplying said oxygen-based gas to said substrate; and radiating the surface of said substrate with light for up to several milliseconds. 17. An apparatus for forming a film comprising: a housing; a table installed in said housing, for supporting a substrate; a gas supply port for supplying a gas into said housing; a gas discharge port for discharging the gas in said housing from said housing; and a heater for heating the surface of a substrate supported on said table by radiating light on to the surface of the substrate placed on said table for up to several milliseconds. 18. The apparatus for forming a thin film according to claim 17 wherein said heater includes a flash lamp. 19. A method of forming a high-dielectric-constant film on a substrate comprising: supplying a first source gas that contains at least one element of elements constituting a high-dielectric-constant film into a housing where a substrate is located; supplying a second source gas into the housing, the second source gas reacting with said first source gas and forming the high-dielectric-constant film; and heating the surface of the substrate by radiating the surface of the substrate with light for up to several milliseconds. 20. The method for forming a high-dielectric-constant film according to claim 19, including radiating the substrate with light for a time in a range of 0.8 to 20 miliseconds. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device using a metal silicate film as a gate insulating film, to a method for manufacturing such a semiconductor device, to an apparatus being available for forming film in such a semiconductor device, and to method being available for forming high-dielectric-constant film in such a semiconductor device. 2. Background Art Accompanying the miniaturization of semiconductor devices, the reduction of thickness of gate insulating films has been demanded. The reduction of thickness of silicon oxide films and silicon oxynitride films (hereafter referred to as “silicon oxide film and the like”), which are used as conventional gate insulating films, is limited due to increase in leak current, and it is difficult to reduce the SiO2-converted film thickness to 1.5 nm or less. Therefore, there has been proposed a method for inhibiting leak current by using a high-dielectric-constant film, such as a metal oxide film, a metal silicate film and a metal aluminate film, which has a higher specific inductive capacity higher than that of silicon oxide film and the like as the gate insulating film; and by increasing the physical film thickness of the gate insulating film. However, when the high-dielectric-constant film is used as the gate insulating film, and a polysilicon electrode is used as the gate electrode, there has been a problem that impurities doped in the polysilicon electrode diffuse into the substrate through the gate insulating film when the impurities are activated, and the transistor properties are deteriorated. In order to solve this problem, a method for introducing nitrogen into the high-dielectric-constant film has been proposed. Specifically, there has been proposed method for forming a high-dielectric constant film composed of a zirconium oxynitride layer or a hafnium oxynitride layer, by forming a metal layer composed of zirconium or hafnium on a substrate, and oxynitriding the metal layer (refer to e.g., Japanese Patent Laid-Open No. 2000-58832). Furthermore, there has also been proposed a method for laminating a lower barrier film consisting of a hafnium-containing silicon oxynitride film, a high-dielectric-constant film consisting of a silicon-containing hafnium oxide film, and an upper barrier film consisting of a silicon-containing hafnium oxide film that contains nitrogen to form a gate insulating film and for controlling the composition of a metal (M), oxygen (O), nitrogen (N) and silicon (Si) in the high-dielectric-constant film and the lower barrier film (refer to e.g., Japanese Patent Laid-Open No. 2003-8011). In a thin-film formation using a high-dielectric-constant material, the ALD (atomic layer deposition) method is generally used. In this method, material gasses are alternately supplied while resetting the chamber to the original state to form each atomic layer. For example, the formation of a hafnium oxide (HfO2) film as a high-dielectric-constant film will be specifically described. First, the chamber is evacuated, argon gas is flowed in the chamber, and the pressure in the chamber is maintained to 0.2 Torr. In this state, hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] is flowed into the chamber while controlling the flow rate, and the Hf material is vaporized and adsorbed on the surface of the substrate. Then, the chamber is purged, and an oxidizing gas such as ozone gas is introduced. Thereafter, the chamber is purged. By repeating such steps for several tens of times, a hafnium oxide (HfO2) film of a thickness of several nanometers can be formed on the surface of the substrate. The introduction of nitrogen into a high-dielectric-constant film reduces flat-band-voltage shift (hereafter referred to as “Vfb shift”) due to the diffusion of impurities. This is estimated because the high-dielectric-constant gate insulating film is densified by nitriding treatment, and the diffusion of impurities is restricted. However, in the above-described conventional method, initial Vfb shift due to the effect of fixed charge or the like is large, and there has been a problem that satisfactory transistor characteristics cannot obtained particularly in P-channel MIS transistors. In addition, a high-dielectric-constant thin film formed using the ALD method generally contains several percent impurities. This is considered because carbon (C), hydrogen (H) or chlorine (Cl) included in material gas using the ALD method remains and is incorporated in the formed film. The impurities remaining in the high-dielectric-constant film may cause fixed charge and trap, and the characteristics of the film is damaged. SUMMARY OF THE INVENTION The one object of the present invention is to restrict initial Vfb shift, to form a gate insulating film having high film quantity, and to achieve satisfactory transistor characteristics. Another object of the present invention is to lower the impurity content in the high-dielectric-constant film of the gate insulating film. According to one aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film and a gate electrode. The gate insulating film is formed on the substrate, and has a nitrogen-containing metal silicate film or a nitrogen-containing metal aluminate film that contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less on the uppermost layer. The gate electrode is formed on the gate insulating film. Another aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film, and a gate electrode. The gate insulating film is formed on the substrate and has a base interface layer, a metal silicate film and a nitrogen-containing metal silicate film. The base interface layer is formed on the substrate. The metal silicate film is formed on the base interface layer, and contains a metal, oxygen and silicon. The nitrogen-containing metal silicate film contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less, oxygen, silicon, and nitrogen. The gate electrode formed on the gate insulating film. Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the upper layer of the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicatefilm containing a metal in a peak concentration of 5 atomic % or more and 40 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less and nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. Another aspect of the present invention, a apparatus for forming a film comprises a housing, a table installed in the housing, for placing a substrate, a gas supply port for supplying a gas into the housing, a gas discharge port for discharging the gas in the housing out of the housing, and a heater. The heater is for heating the surface of the substrate by radiating light on the surface of the substrate placed on the table for a time up to several milliseconds. Another aspect of the present invention, in a method for forming a high-dielectric-constant film on a substrate, a first material gas that contains at least one element in elements constituting the high-dielectric-constant film is supplied into a housing wherein the substrate is placed. A second material gas that reacts with the first material gas and forms the high-dielectric-constant film is supplied into the housing. The surface of the substrate is heated by radiating light onto the surface of the substrate for a time up to several milliseconds. Other and further objects, features and advantages of the invention will appear more fully from the following description. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view for illustrating a semiconductor device in the first embodiment of the present invention; FIG. 2 is a flow diagram for illustrating a method for forming a metal silicate film in the first embodiment of the present invention; FIG. 3 is a graph showing the relationship between the number of cycles and the thickness of the hafnium oxide film when the hafnium oxide film is formed using tetramethylethylamide as an Hf material; FIGS. 4A and 4B are graphs showing the relationship between the number of cycles and the thickness of the silicon oxide film when the silicon oxide film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as an Si material; FIG. 5 is a graph showing the relationship between the number of cycles and the thickness of the Hf silicate film when a hafnium oxide film is formed using hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as a Hf material, and a silicon oxide film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as a Si material; FIG. 6 is a graph showing the relationship between the Hf/Si ratio and the Hf content in the Hf silicate film [Hf/(Hf+Si)] in the case wherein a hafnium oxide film is formed using hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as a Hf material and a silicon oxide film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as a Si material; FIG. 7 is a flow diagram for illustrating the method for manufacturing a semiconductor device in the first embodiment of the present invention; FIGS. 8A to 10C are sectional views for illustrating the process for manufacturing a semiconductor device in the first embodiment of the present invention; FIGS. 11A and 11B are a graphs showing the C-V characteristics of a semiconductor device in the first embodiment of the present invention; FIG. 12 is a schematic diagram for illustrating a thin film forming apparatus in the second embodiment of the present invention; FIG. 13 is a flow diagram for illustrating the method for forming a metal silicate film in the second embodiment of the present invention; and FIG. 14 is a graph for illustrating the sequence in the method for forming a metal silicate film in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment of the present invention will be described referring to the drawings. In each of the drawings, the same or like parts will be denoted with the same reference numerals, and the description thereof will be simplified or omitted. First Embodiment FIG. 1 is a sectional view for illustrating a semiconductor device according to the first embodiment of the present invention. Specifically, FIG. 1 is a sectional view for illustrating a P-channel MOS transistor (hereafter referred to as “PMOS transistor”). In the PMOS, a substrate 1 is a p-type silicon substrate. As FIG. 1 shows, an n-type well 2 to which an n-type impurity is introduced is formed in the substrate 1. An element-isolating structure 3 is formed on the element-isolating region of the substrate 1. By the element-isolating structure 3, a PMOS transistor-forming region, which is an active region, is partitioned. The element-isolating structure 3 is an STI (shallow trench isolation) formed by filling a shallow trench formed from the surface side of the substrate 1 with a silicon oxide film. On the substrate 1 of the MOS transistor-forming region, gate insulating films 4a, 5a and 6a are laminated and a gate electrode 7b is formed through the gate insulating films 4a, 5a and 6a. The gate insulating film has a base interface layer 4a formed on the substrate 1, a high-dielectric-constant film 5a formed on the base interface layer 4a, and an upper layer insulating film 6a formed on the high-dielectric-constant film 5a. The base interface layer 4a is silicon oxide film for repressing the reaction at the interface. The thickness of the base interface layer 4a is preferably 1 nm or below, for example, about 0.5 nm. The high-dielectric-constant film 5a is a metal silicate film that contains a metal, oxygen and silicon, and for example, an Hf (hafnium) silicate film or a Zr (zirconium) silicate film can be used. The thickness of the high-dielectric-constant film 5a is, for example, about 3 nm. The upper layer insulating film 6a is a nitrogen-containing metal silicate film that contains a metal, oxygen, silicon and nitrogen, and for example, a nitrogen-containing Hf silicate film or a nitrogen-containing Zr silicate film can be used. The upper layer insulating film 6a is a film containing a metal such as Hf and Zr in a peak concentration of 1 atomic % or more and 30 atomic % or less. That is, the nitrogen-containing metal silicate film 6a is a silicon-rich film. This is because if the peak concentration of the metal exceeds 30 atomic %, satisfactory electrical properties cannot be obtained as described later. The upper layer insulating film 6a also contains nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less. This is because if the peak concentration of nitrogen is less than 10 atomic %, the densification of the upper layer insulating film 6a becomes insufficient, and in the activating heat treatment, the inhibition of the diffusion of impurities such as phosphorus and boron introduced into polysilicon, which is the gate electrode, becomes difficult to control. It is practically impossible to make the peak concentration of nitrogen exceed 30 atomic %, and even if it is possible, excellent electrical properties cannot be obtained. The thickness of the upper layer insulating film 6a is preferably about 1/20 to 2/3 the thickness of the high-dielectric-constant film 5a. The gate electrode 7b is a polysilicon electrode consisting of a doped silicon film formed by introducing an impurity into a polysilicon film. The polysilicon electrode can be substituted by a silicon-germanium (SixGey) can be used as the gate electrode 7b. On the sides of the gate electrode 7b, and gate insulating films 4a, 5a and 6a, a sidewall 11 is formed as a spacer for forming LDD. The sidewall 11 consists of a silicon oxide film or a silicon nitride film. Across the channel region on the surface of the substrate 1 below the gate electrode 7b, an extension region 14 of lower concentration is formed by introducing a p-type impurity. A source-drain region 15 of higher concentration is formed by introducing a p-type impurity on the n-type well 2 so as to connect to the extension region 14. An interlayer insulating film 16, such as BPSG, BSG and PSG, is formed so as to coat the gate electrode 7b. In the interlayer insulating film 16, contact hole connected to the source-drain region 15 are formed, and in the contact holes, contacts 17, in which conductive films such as a laminated films of barrier metal films and tungsten films are buried, are formed. Metal wirings 18 are formed on the contacts 17. The present invention can be applied not only to the above-described PMOS transistor, but also to an N-type channel MOS transistor (here after referred to as “NMOS transistor”) having the same cross-sectional structure. In the case of an NMOS transistor, a p-type well is formed in a p-type substrate 1, and an NMOS transistor-forming region is partitioned by an element isolating structure 3. Furthermore, in the p-type well, an extension region of a lower concentration formed by introducing an n-type impurity, and a source-drain region of a higher concentration formed by introducing an n-type impurity and connected to the extension are formed. FIG. 2 is a flow diagram for illustrating a method for forming a metal silicate film in the second embodiment of the present invention. The method for forming a metal silicate film as the above-described high-dielectric-constant film 5 will be described below referring to FIG. 2. Specifically, a method for forming an Hf silicate film will be described. The Hf silicate film is formed by the combination of a step for forming a hafnium oxide film (HfO2 film) using the ALD (atomic layer deposition) method, and a step for forming a silicon-oxide film (SiO2 film.) using the ALD method, and by controlling the number of each step. The details of each step will be described below. First, the step for forming a hafnium oxide film will be described. The hafnium oxide film is formed by controlling the flow rate of hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as an Hf material using a mass flow controller, gasifying the flow-rate-controlled Hf material, adsorbing the gasified Hf material on the surface of a silicon substrate held in a film-forming chamber (Step S102), and then introducing an oxidizing gas such as ozone gas into the chamber (Step S104). The above steps for forming the hafnium oxide film are made one cycle. FIG. 3 is a graph showing the relationship between the number of cycles and the thickness of the hafnium oxide film when the hafnium oxide film is formed using tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as an Hf material. FIG. 3 shows change in film thickness when the substrate temperature is 200° C., 275° C., 300° C. and 325° C. As FIG. 3 shows, the thickness of the hafnium oxide film increases linearly with increase in the number of cycles at each temperature of the silicon wafer. Furthermore, with the rise of substrate temperature, the gradient of the straight line increases, and the film-forming speed per cycle increases. This is considered because the quantity of tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] adsorbed on the surface of the substrate increases with the rise of substrate temperature. As FIG. 3 shows, the speed of HfO2 film formation per cycle at each substrate temperature was 0.090 nm/cycle at 200° C., 0.093 nm/cycle at 250° C., 0.117 nm/cycle at 275° C., 0.227 nm/cycle at 300° C., and 0.458 nm/cycle at 325° C. As an Hf material, hafnium tetradimethylamide [Hf(N(CH3)2)4] or hafnium tetradiethylamide [Hf(N(C2H5)2)4] can be used. In place of an Hf silicate film, a Zr silicate film can be formed. In this case, as a Zr material, zirconium tetramethylethylamide [Zr(N(CH3)(C2H5)2)4], zirconium tetradimethylamide [Zr(N(CH3)2)4] or zirconium tetradiethylamide [Zr(N(C2H5)2)4] can be used. As a metal, tantalum (Ta), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb), and lutetium (Lu) other than Hf or Zr can be used. In these cases, materials wherein the hafnium in the above Hf materials is substituted by each metal element can be used. Next, the step for forming a silicon oxide film will be described. The silicon oxide film is formed by controlling the flow rate of tris(dimethylamino)silane [SiH(N(CH3)2)3] as an Si material using a mass flow controller, gasifying the flow-rate-controlled Si material, adsorbing the gasified Si material on the surface of a silicon substrate held in a film-forming chamber (Step S106), and then introducing an oxidizing gas such as ozone gas into the chamber (Step S108). The above steps for forming the silicon oxide film are made one cycle. FIG. 4 is a graph showing the relationship between the number of cycles and the thickness of the silicon oxide film when the silicon oxide film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as an Si material. FIG. 4A shows the results when the pressure in the film-forming chamber is 0.5 Torr; and FIG. 4B shows the results when the pressure in the film-forming chamber is 5.0 Torr. When the pressure in the film-forming chamber is 0.5 Torr, as FIG. 4A shows, although the thickness of a silicon oxide film linearly increased with increase in the number of cycles, the film-forming speed was low. On the other hand, when the pressure in the film-forming chamber is raised to 5.0 Torr, as FIG. 4B shows, the film-forming speed increased largely. This is considered because tris(dimethylamino)silane [SiH(N(CH3)2)3], which is an Si material, is difficult to adsorb on the surface of the substrate at a pressure as low as 0.5 Torr, and the quantity of adsorption increases by raising the pressure to 5.0 Torr. As FIG. 4B shows, when the film was formed under alow pressure of 0.5 Torr, the speed of forming the SiO2 film per cycle at each substrate temperature was 0.058 nm/cycle at 225° C., 0.070 nm/cycle at 250° C., and 0.080 nm/cycle at 275° C. As an Si material, tris(dimethylamino)silane [SiH(N(CH3)2)3], tetrakis(dimethylamino)silane [SiH(N(CH3)2)4], tetrakis(diethylamino)silane [SiH(N(C2H5)2)4], dimethylsilane [SiH2(CH3)2], diethylsilane [SiH2(C2H5)2], or bis-tert-butylaminosilane [SiH2(NH(C4H9)2) can be used. FIG. 5 is a graph showing the relationship between the number of cycles and the thickness of the Hf silicate film when a hafnium oxide (HfO2) film is formed using hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as a Hf material, and a silicon oxide (SiO2) film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as a Si material. The formation of the hafnium oxide film and the silicon oxide film is as described above. In FIG. 5, Hf/Si=1/1 means that HfO2 film formation and SiO2 film formation are performed in every other cycle in a cycle of the step for forming the Hf silicate film. Hf/Si=1/2 means that after HfO2 film formation has been performed once, SiO2 film formation is performed twice; and Hf/Si=1/4 means that after HfO2 film formation has been performed once, SiO2 film formation is performed four times. In either cycle ratio, the pressure in the film-forming chamber in HfO2 film formation was 0.5 Torr, and the pressure in the film-forming chamber in SiO2 film formation was 5.0 Torr. The substrate temperature was 275° C. As FIG. 5 shows, in either Hf/Si=1/1, Hf/Si=1/2 or Hf/Si=1/4, the thickness of the Hf silicate film was linearly increased with increase in the number of cycles. This means that the thickness of the Hf silicate film can be controlled very accurately by controlling the number of cycles. The speed of forming the Hf silicate film per cycle was 0.155 nm/cycle when Hf/Si=1/1, 0.222 nm/cycle when Hf/Si=1/2, and 0.373 nm/cycle when Hf/Si=1/4 as shown in FIG. 5. Hf materials and Si materials can be duly changed to the above-described other materials. FIG. 6 is a graph showing the relationship between the Hf/Si ratio and the Hf content in the Hf silicate film [Hf/(Hf+Si)] in the case wherein a hafnium oxide film is formed using hafnium tetramethylethylamide [Hf(N(CH3)(C2H5)2)4] as a Hf material and a silicon oxide film is formed using tris(dimethylamino)silane [SiH(N(CH3)2)3] as a Si material. Here, the HfO2 film and the SiO2 film were formed under different pressures in the film-forming chamber, and the pressure in HfO2 film formation was 0.5 Torr and that in SiO2 film formation was 5.0 Torr. The substrate temperature was 275° C. As FIG. 6 shows, by controlling the Hf/Si ratio, that is the ratio of the number of steps for forming the HfO2 film to the number of steps for forming the SiO2 film in a cycle of the formation of the Hf silicate film, the Hf concentration in the Hf silicate film can be accurately controlled within a wide range of 1/30 to about 1. Therefore, byusing the above-described method, the peak concentration of the metal in the metal silicate film can be accurately controlled. The method for manufacturing the semiconductor device in the first embodiment will be described. FIG. 7 is a flow diagram for illustrating the method for manufacturing a semiconductor device according to the first embodiment. FIGS. 8A to 10C are sectional views for illustrating the process for manufacturing a semiconductor device according to the first embodiment. Specifically, FIGS. 8A to 10C are sectional views for illustrating the process for manufacturing a PMOS transistor. Since an NMOS transistor has the similar cross-sectional structure to a PMOS transistor, the drawings illustrating the method for manufacturing an NMOS transistor will be omitted, and the process will be described when required. First, as FIG. 8A shows, in the PMOS transistor-forming region, an n-type impurity is introduced into a P-type silicon substrate 1, and heat treatment is carried out to form an n-type well 2. On the other hand, in the NMOS transistor-forming region, a p-type impurity is introduced into the silicon substrate 1, and heat treatment is carried out to form a p-type well.(Step S202). Then, by forming an element-isolating region 3 using the STI method, the PMOS and NMOS transistor-forming regions are partitioned (Step S204). Specifically, the element-isolating region 3 is formed by forming a shallow trench in the element-isolating region of the silicon substrate 1, and burying a silicon oxide film in the trench. The silicon oxide film formed out of the trench can be removed using the CMP method or the etch-back method. Next, the surface of the silicon substrate is cleaned using diluted hydrofluoric acid (DHF) (Step S206). Thereafter, as FIG. 8B shows, a silicon oxide film 4 of a thickness of, for example, about 0.5 nm is formed on the surface of the silicon substrate 1 by a rapid heat treatment using a halogen lamp or a flash lamp (Step S208). After the extremely thin silicon oxide film 4 has been formed, an Hf silicate film 5 of a thickness of, for example, about 3 nm is formed using the above-described method (Step S210). After the Hf silicate film 5 has been formed, and before a nitrogen-containing Hf silicate film 6 is formed, a treatment for the densification of the Hf silicate film 5 may be carried out (Step S212). The densification treatment can be carried out, for example, by performing rapid heat treatment using a halogen lamp in a nitrogen-gas atmosphere wherein a trace of oxygen gas is added, or in a nitrogen-gas atmosphere for 1 to 600 sec. Alternatively, the densification treatment can be carried out by performing rapid heat treatment using a flash lamp in the same atmosphere for 0.8 to 20 msec. Next, as FIG. 8C shows, a nitrogen-containing Hf silicate film 6 containing Hf of a peak concentration of 1 atomic % or more and 30 atomic % or less, and nitrogen of a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the upper layer of the Hf silicate film 5 (Step S214). The nitrogen-containing Hf silicate film 6 can be formed by the plasma treatment using a nitrogen-based gas. In place of forming the nitrogen-containing Hf silicate film 6 by nitriding the Hf silicate film 5, the nitrogen-containing Hf silicate film 6 may be formed on the Hf silicate film 5 using a material that contains hafnium, oxygen, silicon and nitrogen. After the nitrogen-containing Hf silicate film 6 has been formed, densification treatment is carried out (Step S216). The densification treatment can be carried out, for example, by rapid heat treatment using a lamp in a nitrogen-gas atmosphere wherein a trace of oxygen gas is added, or in a nitrogen-gas atmosphere. Next, as FIG. 8D shows, a polysilicon film 7 that will finally become a gate electrode is formed on the nitrogen-containing Hf silicate film 6 (Step S218). Then, as FIG. 9A shows, an impurity 8 such as boron is ion-implanted into the polysilicon film 7 (Step S220). Thereby, a doped polysilicon film 7a is formed on the nitrogen-containing Hf silicate film 6. On the other hand, although not shown in the drawings, an impurity such as phosphorus is ion-implanted into a polysilicon film formed on the NMOS transistor-forming region. Next, a resist pattern (not shown) is formed on the doped polysilicon film 7a (Step S222), and using the resist pattern as a mask, the doped polysilicon film 7a, the nitrogen-containing Hf silicate film 6, the Hf silicate film 5, and the silicon oxide film 4 are sequentially etched (Step S224). Thereby, as FIG. 9B shows, a polysilicon gate electrode 7b is formed on the n-type well 2 of the silicon substrate 1, through the gate insulating film formed by laminating the silicon oxide film 4a, the Hf silicate film 5a, and the nitrogen-containing Hf silicate film 6a. Then, a low concentration of boron difluoride (BF2) is ion-implanted into the n-type well 2 using the gate electrode 7b as a mask. Thereby, in the n-type well 2, a p-type low-concentration ion-implanted layer 10 that will finally become an extension region is formed on the upper layer of the silicon substrate 1 on the both sides of the gate electrode 7b. On the other hand, although not shown in the drawings, in the NMOS transistor-forming region, arsenic is ion-implanted into the p-type well to form an n-type low-concentration ion-implanted layer (Step S226). Next, a silicon nitride film having a thickness of, for example, about 100 nm is formed on the entire surface of the silicon substrate 1 so as to coat the gate electrode 7b, and the silicon nitride film is subjected to anisotropic etching. Thereby, as FIG. 9C shows, a sidewall 11 consisting of the silicon nitride film is formed in a self-aligning manner (Step S228). Next, as FIG. 10A shows, boron 12 is ion-implanted into the n-type well 2 as a high-concentration P-type impurity 12 using the gate electrode 7b and the sidewall 11 as masks. Thereby, a p-type high-concentration ion-implanted layer 13 that will finally become the source/drain region is formed in the n-type well 2. On the other hand, although not shown in the drawings, in the NMOS transistor-forming region, phosphorus is ion-implanted into the p-type well to form an n-type high-concentration ion-implanted layer (Step S230). Next, rapid heat treatment using a lamp is performed (Step S232). Thereby, as FIG. 10B shows, the p-type low-concentration ion-implanted layer 10 and the p-type high-concentration ion-implanted layer 13 in the n-type well 2 are activated, and the p-type extension region 14 wherein an impurity is introduced in a low concentration, and the p-type source/drain region 15 wherein an impurity is introduced in a high concentration are formed. On the other hand, although not shown in the drawings, in the NMOS transistor-forming region, the n-type low-concentration ion-implanted layer and the n-type high-concentration ion-implanted layer in the p-type well are activated, and the n-type extension region wherein an impurity is introduced in a low concentration, and the n-type source/drain region wherein an impurity is introduced in a high concentration are formed. Here, the temperature of heat treatment for activation is preferably at least 10 degrees lower than the temperature of heat treatment for densification. For example, heat treatment for activation can be performed at 980° C., and heat treatment for densification can be performed at 1000° C. Thereby, the interaction between the gate insulating film and the gate electrode is inhibited, and the thermally stable gate insulating film wherein the diffusion of the impurity introduced into the gate electrode is inhibited can be obtained. Next, as FIG. 10C shows, an interlayer insulating film 16 is formed on the entire surface of the substrate using the CVD method. Thereafter, a resist pattern (not shown) is formed on the insulating film 16 using a lithography techniques, contact holes connected to the source/drain region 15 are formed in the interlayer insulating film 16 by dry etching using the resist pattern as masks, and then a barrier metal film and a tungsten film are buried in the contact holes to form contacts 17. The unnecessary barrier metal film and tungsten film are removed using the CMP method. Thereafter, metal wirings 18 are formed on the contacts 17 to manufacture the semiconductor device shown in FIG. 1. Next, the gate capacity-gate voltage characteristics (hereafter referred to as “C-V characteristics”) of the MOS transistor manufactured in this embodiment will be described. FIG. 11 is a graph showing the C-V characteristics of a semiconductor device according to the first embodiment. Specifically, FIG. 1A is a graph showing the C-V characteristics of an NMOS transistor; and FIG. 11B is a graph showing the C-V characteristics of a PMOS transistor. As FIGS. 11A and 11B show, when an Hf silicate film is formed in Hf/Si=1/1 (above described), the C-V characteristics of an actually obtained MOS transistor are deviated from ideal C-V characteristics. This is because the initial Vfb shift is not inhibited. On the other hand, when an Hf silicate film is formed in Hf/Si=1/2, the C-V characteristics are close to ideal C-V characteristics. Furthermore, when an Hf silicate film is formed in Hf/Si=1/4, that is, when the metal concentration [hf/(Hf+Si)] is about 30% or less, substantially ideal C-V characteristics can be obtained. Therefore, it is understood that the initial Vfb is sufficiently inhibited. Thus, better C-V characteristics could be obtained by forming a silicon-rich Hf silicate film, and a substantially ideal C-V curve was obtained when the metal concentration was about 30% or less. Especially, as FIG. 11B shows, marked improvement of C-V characteristics was achieved in the PMOS transistor. In addition, as FIGS. 11A and 11B show, it is known that the C/Cmax value varies depending on the Hf/Si ratio in the reverse side, and with increase in the concentration of silicon, the C/Cmax value increases. This is considered because as the concentration of silicon in the Hf silicate film increases, the diffusion of impurities from the upper electrode polysilicon decreases, and depletion is minimized. The same results can also be obtained in the case of the Hf silicate formation using the above-described other Hf materials or Si materials. According to this embodiment, as described above, the peak concentration of the metal in the nitrogen-containing Hf silicate film 6a positioned on the uppermost layer of the gate insulating film was controlled to 1 atomic % or more and 30 atomic % or less. Thereby, the initial Vfb shift could be sufficiently inhibited, and C-V characteristics equivalent to ideal C-V characteristics could be obtained. Further, the peak concentration of nitrogen in the nitrogen-containing Hf silicate film 6a was controlled to 10 atomic % or more and 30 atomic % or less. Thereby, the diffusion of impurities introduced into the gate electrode in the activating heat treatment could be inhibited, and the Vfb shift due to the diffusion of impurities could be inhibited. In the first embodiment, the case of using a metal silicate film as the high-dielectric-constant film 5, and using a nitrogen-containing metal silicate film as the upper layer insulating film 6 was described. However, for example, the present invention can be applied to the case of using a metal aluminate film as the high-dielectric-constant film, and using a nitrogen-containing metal aluminate film as the upper layer insulating film, and the similar results can also be obtained from this case. Next, the modification on the first embodiment will be described. In the above-described embodiment, the peak concentration of the metal was equivalent in the metal silicate film 5a and in the nitrogen-containing metal silicate film 6a. In this modification, however, the peak concentration of the metal in the metal silicate film 5a was higher than that in the nitrogen-containing metal silicate film 6a. In other words, the metal silicate film 5a was made to be a metal-rich film; and the nitrogen-containing metal silicate film 6a was made to be a silicon-rich film. Since other constitution is the same as in the above-described embodiment, the description thereof will be omitted. In this modification, a metal silicate film (e.g., Hf silicate film or Zr silicate film) as the high-dielectric-constant film 5a was made to be a metal-rich film that contains a metal in the peak concentration of 5 atomic % or more and 40 atomic % or less. In the method for manufacturing a semiconductor device according to the above-described embodiment, after a silicon oxide film 4 has been formed, for example, a hafnium-rich Hf silicate film is formed in the ratio of Hf/Si=1/2. On the Hf silicate film, a silicon-rich Hf silicate film is formed in the ratio of Hf/Si=1/4. Thereafter, the silicon-rich Hf silicate film is nitrided to form a silicon-rich nitrogen-containing Hf silicate film as the upper layer insulating film. Thereafter, in the same manner as in the above-described embodiment, a polysilicon film 7 is formed on the nitrogen-containing Hf silicate film. In this modification, by making the film on the uppermost layer of the gate insulating film a nitrogen-containing metal silicate film that contains the metal in the peak concentration of 1 atomic % or more and 30 atomic % or less, the similar effect as in the above-described embodiment can also be obtained. Furthermore, this modification can improve the total effective specific dielectric constant of the gate insulating film by the use of a metal-rich metal silicate film as the high-dielectric-constant film 5a. Second Embodiment The semiconductor device and the method for the manufacture thereof according to the second embodiment is the same as those described in the first embodiment. In the second embodiment, however, a different method is used to form a metal silicate such as an Hf silicate. This will be described below in detail. FIG. 12 is a schematic diagram for illustrating a thin film forming apparatus in the second embodiment of the present invention. As FIG. 12 shows, the thin film forming apparatus 100 is equipped with a vacuum chamber 20. On the central portion in the chamber 20, a table 21 is disposed. In the table 21, a heater 22 is installed to heat the table from the bottom thereof to a predetermined temperature. Above the table 21, a gas supply pipe 23 is installed so as to pass through a portion of the outer wall of the chamber 20. In other words, the gas supply pipe 23 passes from the outside of the chamber 20 to the inside of the chamber 20, and thereby supplies the gas into the chamber 20. The gas supply pipe 23 is also disposed so as to surround upside of the table 21. The gas supply pipe 23 has a plurality of ejection nozzles 24. The gas supplied from the gas supply pipe 23 is ejected through these ejection nozzles 24 into the chamber 20. A total of two gas discharge ports 25 are installed so as to pass through the underside of the outer wall of the chamber 20. The gas discharge ports 25 run from the inside to the outside of the chamber 20, and are connected to a vacuum pump through a valve 26. Thereby the gas in the chamber 20 can be discharged to the exterior. The ceiling portion of the chamber 20, facing the table 21, is formed of a quartz window 27. In the upper portion of the quartz window 27, a total of 50 flash lamps 28 are disposed, and the flash lamps 28 are covered with a reflective plate 29. The flash lamps 28 are connected to a capacitor 30, and the capacitor 30 is connected to a power source 31. In the thin film forming apparatus 100, the ceiling portion of the chamber 20 is formed of a quartz window 27 that permeates light so as to introduce light emitted from the flash lamps 28. The reflective plate 29 is installed so as to reflect the light emitted from the flash lamps 28 toward the opposite side to the chamber 20 (upward in FIG. 12) to the chamber 20, and to introduce the light into the chamber 20. The current from the power source 31 is charged into the capacitor 30, and instant discharge of the electric charge makes the flash lamp 28 emit light. In the second embodiment, a metal silicate is formed using the thin film forming apparatus 100 constituted as described above, in place of the steps S102 to S110 (S210) in the manufacturing process of the semiconductor device described in the first embodiment. In this case a substrate 32 is placed on the table 21. FIG. 13 is a flow diagram for illustrating the method for forming a metal silicate film in the second embodiment of the present invention; and FIG. 14 is a graph for illustrating the sequence in the method for forming a metal silicate film in the second embodiment. In the second embodiment, the metal silicate film is also formed by individually forming a hafnium oxide film and a silicon oxide film. This will be specifically described referring to FIGS. 12 to 14. First, a hafnium oxide film is formed. Here, first, the table 21 is heated in the state where a substrate 32 is placed on the table 21 (Step S302). Here, the table 21 is heated using the heater 22 to a temperature of 300° C. Thereby, the temperature of the substrate 32 is maintained at 300° C. Next, the gas in the chamber 20 is discharged (Step S304). Gas discharge is performed by opening the valve 26 and sucking the gas through the gas discharge ports 25 using the vacuum pump until the pressure in the chamber 20 becomes 10−7 Torr. Thereafter, argon gas is supplied into the chamber 20 (Step S306). The argon gas is supplied through the gas supply pipe 23, and is ejected through the ejection nozzles 24 into the chamber 20. The pressure in the chamber 20 is fixed to 0.5 Torr. After the chamber 20 has been maintained in this state, the introduction of the material gas is started. Referring to FIG. 14, the supply of hafnium tetramethylethylamide is started at the point A1 (Step S310). Hafnium tetramethylethylamide is supplied through the gas supply pipe 23, and is ejected through the ejection nozzles 24 into the chamber 20. The supply of hafnium tetramethylethylamide is performed at 2 sccm, for 1.5 seconds, and the supply is stopped at the point B1 1.5 seconds later (Step S312). Thereafter, the purge of the gas in the chamber 20 is started (Step S314). Here, argon gas is supplied through the gas supply pipe 23 for about 5 seconds. On the other hand, the valve 26 is opened and the gas in the chamber 20 is discharged through the gas discharge ports 25 with the vacuum pump. The supply of argon gas and gas discharge are stopped at the point C1 5 seconds later (Step S316). At this time, the valve 26 is closed. Thereafter, the supply of ozone gas is started (Step S318). In the same manner as hafnium tetramethylethylamide, ozone gas is also supplied through the gas supply pipe 23, and is ejected through the ejection nozzles 24 into the chamber 20. The supply of ozone gas is performed at 5 sccm for 2 seconds, and the supply is stopped at the point D1 2 seconds later (Step S320). Thereafter, the discharge of the gas from the chamber 20 is started (Step S322). In the same manner as the discharge performed after the supply of hafnium tetramethylethylamide, the gas is purged by supplying argon gas through the gas supply pipe 23, and simultaneously the valve 26 is opened to discharge the gas through the gas discharge ports 25 using the vacuum pump. At the point E1, 6 seconds after gas purge was started, the light emitting of the flash lamps 28 is performed (Step S324). The energy of the light-emitting flash lamps 28 is 15 J/cm2. The light emitting time of the flash lamps 28 is as an extremely short time such as about 5.0 to 20 msec, and thereby only the surface of the substrate 32 is heated instantly. At the point A2, 8 seconds after gas purge was started, the supply of argon gas and the discharge of the gas from the chamber 20 are stopped (Step S326). Thereafter, the introduction of hafnium tetramethylethylamide is started again (Step S310), and steps S310 to S326 are repeated. Thus, the introduction of hafnium tetramethylethylamide (Steps S310 and S312), the purge of the gas (Steps S314 and S316), the introduction of ozone gas (Steps S318 and S320), the purge of the (Steps S322 and S326), and the light emitting of the flash lamps during the purge of the gas (Step S324) are repeated for 20 times, and the formation of the thin film is completed. Thereby, a hafnium oxide film of a thickness of about 2.5 nm can be formed on the substrate 32. Next, in the same manner, a silicon oxide film is formed. First, the table 21 is maintained at about 300° C. in the same manner as in the formation of the hafnium oxide film. The chamber 20 is purged with argon gas, and the pressure in the chamber 20 is fixed to 5.0 Torr. After the chamber 20 is maintained in this state, the introduction of the material gas is started. Referring again to FIG. 14, the supply of trisdimethylaminosilane as the Si material is started at the point A1 (Step S330). Trisdimethylaminosilane is supplied through the gas supply pipe 23, and is ejected through the ejection nozzles 24 into the chamber 20. The supply of trisdimethylaminosilane is performed at 2 sccm for 1.5 seconds, and the supply is stopped at the point B1 1.5 seconds later (Step S332). Thereafter, the purge of the gas in the chamber 20 is started (Step S334). Here, argon gas is supplied through the gas supply pipe 23 for about 5 seconds, and on the other hand, the valve 26 is opened. The gas in the chamber 20 is discharged through the gas discharge ports 25 with the vacuum pump, and the purge of the gas is stopped at the point C1 5 seconds later (Step S336). Thereafter, the supply of ozone gas is started (Step S338). In the same manner as trisdimethylaminosilane, ozone gas is also supplied through the gas supply pipe 23, and is ejected through the ejection nozzles 24 into the chamber 20. The supply of ozone gas is performed at 5 sccm for 2 seconds, and the supply is stopped at the point D1 2 seconds later (Step S340). Thereafter, the discharge of the gas from the chamber 20 is started (Step S342). In the same manner as the discharge performed after the supply of trisdimethylaminosilane, the gas is purged by supplying argon gas through the gas supply pipe 23, and simultaneously the valve 26 is opened to discharge the gas through the gas discharge ports 25 using the vacuum pump. At the point E1, 6 seconds after the purge of the gas was started, the light emitting of the flash lamps 28 is performed (Step S344). The energy of the light-emitting flash lamps 28 is 15 J/cm2. The light-emitting time of the flash lamps 28 is as an extremely short time such as about 5.0 to 20 msec, and thereby only the surface of the substrate 32 is heated instantly. At the point A2, 8 seconds after the purge of the gas was started, the purge of the gas in the chamber 20 is stopped (Step S346). Thereafter, the introduction of trisdimethylaminosilane is started again (Step S330), and steps S330 to S346 are repeated. Thus, the introduction of trisdimethylaminosilane (Steps S330 and S332), the purge of the gas (Steps S334 and S336), the introduction of ozone gas (Steps S338 and S340), the purge of the gas (Steps S342 and S346), and the light emitting of the flash lamps 28 during the purge of the gas (Step S344) are repeated for 5 times, and the formation of the thin film is completed. Thereby, a silicon oxide film of a thickness of about 0.4 nm can be formed on the substrate 32. Thereafter, the steps S212 to S232 described in the first embodiment is carried out to form a semiconductor device according to the second embodiment. Here, the formed hafnium oxide film in the second embodiment was compared with an aluminum oxide film formed according to a conventional method, wherein the sequence of the supply of the material gas and the purge of the gas is performed in the same manner, but without heating with the flash lamps 28, using a secondary ion mass spectrometer, and it was found that the quantity of residual carbon in the thin film was lowered to about 1/10. This is considered that since heating of the millisecond order can be performed by heating by flash lamps, the temperature of the surface of the substrate 32 can be raised instantly to accelerate the reaction, and the temperature of the substrate 32 can be immediately lowered to the original temperature. Whereas, in the case of using the conventional ALD method, after supplying the material gas, an oxidizing gas such as ozone gas is supplied to start oxidation reaction. However, at this time, since the temperature of the wafer is low, and the reaction time is not sufficiently long, the oxidation reaction is not completed. This is considered to be the cause of residual impurities in the film. In the ALD method, however, since the reaction rate of the film is low, the reaction time cannot be made sufficiently long when productivity is considered. Since chemical kinetics teaches that the reaction rate is the exponential function of temperature, it is considered to raise temperature to increase the reaction rate. However, in an apparatus used for the conventional ALD method, it is considered that if the temperature of a wafer is simply raised, decomposition begins only by supplying the material gas. For example, if hafnium tetramethylethylamide is supplied at a high substrate temperature, the hafnium tetramethylethylamide is decomposed by itself, and a carbon-containing hafnium film is formed. Therefore, temperature cannot be raised in the conventional ALD. On the other hand, according to the formation of a metal silicate film in the above-described embodiment, the flash lamps 28 can heat the surface of a wafer for the millisecond order and can raise the surface temperature of the wafer instantly to accelerate the rate of reaction. Also since only the surface of the substrate 32 is heated for an extremely short time, the wafer temperature can be immediately returned to the original temperature. Therefore, the next cycle (Steps S310 to S324) can be performed at the original wafer temperature. Thereby, a high-dielectric-constant thin film having a low impurity concentration and good characteristics can be formed. In the second embodiment, the case wherein a thin film forming apparatus 100 is used for forming the metal silicate film of a semiconductor device was described. However, the present invention is not limited thereto, but the thin film forming apparatus 100 can be applied to the formation of other thin films. In the second embodiment, the case wherein 50 flash lamps 28 are used was described; however, the thin film forming apparatus of the present invention is not limited to the apparatus using. 50 flash lamps. Further in this embodiment, flash lamps 28 are used as the heating means. However, the heating means in the present invention is not limited to the flash lamps, but other means can be used as long as the surface of the substrate can be adequately heated. Also in the second embodiment, the case wherein the heating time by the flash lamps is 5.0 to 20 milliseconds was described. However, the heating time in the present invention is not limited to this range. However, when the lowering of the impurity concentration contained in the high-dielectric-constant film is considered, it is considered that the heating time is preferably 0.8 milliseconds or longer. In this embodiment, the upper portion of the chamber 20 was made to be a quartz window 27, through which light from the flash lamps 28 was transmitted to irradiate the substrate in the chamber 20. Furthermore, the case wherein a reflective plate 29 is installed above the flash lamps 28 so as to reflect light emitted upward and irradiate the chamber 20 was described. However, the constitution of the thin film forming apparatus according to the present invention is not limited thereto, but other constitution, for example, the constitution wherein the flash lamps 28 are directly installed in the chamber 20, can be used. Further in this embodiment, the case wherein ejecting nozzles 24 are installed in the gas supply pipe 23, and a vacuum pump is installed in the gas discharge ports 25 through a valve 26 to discharge the gas was described. However, the thin film forming apparatus of the present invention is not limited to the apparatus having such a constitution, but other constitutions can be used as long as the gas can be supplied into the chamber 20, and the gas can be adequately-discharged from the chamber 20. The other constitutions of the thin film forming apparatus of the present invention are not limited to the constitution described in this embodiment, but other constitutions can be used as long as the surface of the substrate can be adequately heated, and the reaction can be accelerated. Furthermore, since the description of the material gas and the like to be used in the second embodiment is the same as those described in the first embodiment, the description thereof was omitted. The features and the advantages of the present invention as described above may be summarized as follows. According to one aspect of the present invention, in a semiconductor device, the metal content in the metal silicate film formed on the uppermost layer of a high-dielectric-constant film is controlled. Accordingly, the semiconductor device having C-V characteristics equivalent to ideal C-V characteristics can be realized. Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may by practiced otherwise than as specifically described. The entire disclosure of a Japanese Patent Application No. 2003-434367, filed on Dec. 26, 2003 including specification, claims, drawings and summary, on which the Convention priority of the present application is based, are incorporated herein by reference in its entirety. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a semiconductor device using a metal silicate film as a gate insulating film, to a method for manufacturing such a semiconductor device, to an apparatus being available for forming film in such a semiconductor device, and to method being available for forming high-dielectric-constant film in such a semiconductor device. 2. Background Art Accompanying the miniaturization of semiconductor devices, the reduction of thickness of gate insulating films has been demanded. The reduction of thickness of silicon oxide films and silicon oxynitride films (hereafter referred to as “silicon oxide film and the like”), which are used as conventional gate insulating films, is limited due to increase in leak current, and it is difficult to reduce the SiO 2 -converted film thickness to 1.5 nm or less. Therefore, there has been proposed a method for inhibiting leak current by using a high-dielectric-constant film, such as a metal oxide film, a metal silicate film and a metal aluminate film, which has a higher specific inductive capacity higher than that of silicon oxide film and the like as the gate insulating film; and by increasing the physical film thickness of the gate insulating film. However, when the high-dielectric-constant film is used as the gate insulating film, and a polysilicon electrode is used as the gate electrode, there has been a problem that impurities doped in the polysilicon electrode diffuse into the substrate through the gate insulating film when the impurities are activated, and the transistor properties are deteriorated. In order to solve this problem, a method for introducing nitrogen into the high-dielectric-constant film has been proposed. Specifically, there has been proposed method for forming a high-dielectric constant film composed of a zirconium oxynitride layer or a hafnium oxynitride layer, by forming a metal layer composed of zirconium or hafnium on a substrate, and oxynitriding the metal layer (refer to e.g., Japanese Patent Laid-Open No. 2000-58832). Furthermore, there has also been proposed a method for laminating a lower barrier film consisting of a hafnium-containing silicon oxynitride film, a high-dielectric-constant film consisting of a silicon-containing hafnium oxide film, and an upper barrier film consisting of a silicon-containing hafnium oxide film that contains nitrogen to form a gate insulating film and for controlling the composition of a metal (M), oxygen (O), nitrogen (N) and silicon (Si) in the high-dielectric-constant film and the lower barrier film (refer to e.g., Japanese Patent Laid-Open No. 2003-8011). In a thin-film formation using a high-dielectric-constant material, the ALD (atomic layer deposition) method is generally used. In this method, material gasses are alternately supplied while resetting the chamber to the original state to form each atomic layer. For example, the formation of a hafnium oxide (HfO 2 ) film as a high-dielectric-constant film will be specifically described. First, the chamber is evacuated, argon gas is flowed in the chamber, and the pressure in the chamber is maintained to 0.2 Torr. In this state, hafnium tetramethylethylamide [Hf(N(CH 3 )(C 2 H 5 ) 2 ) 4 ] is flowed into the chamber while controlling the flow rate, and the Hf material is vaporized and adsorbed on the surface of the substrate. Then, the chamber is purged, and an oxidizing gas such as ozone gas is introduced. Thereafter, the chamber is purged. By repeating such steps for several tens of times, a hafnium oxide (HfO 2 ) film of a thickness of several nanometers can be formed on the surface of the substrate. The introduction of nitrogen into a high-dielectric-constant film reduces flat-band-voltage shift (hereafter referred to as “Vfb shift”) due to the diffusion of impurities. This is estimated because the high-dielectric-constant gate insulating film is densified by nitriding treatment, and the diffusion of impurities is restricted. However, in the above-described conventional method, initial Vfb shift due to the effect of fixed charge or the like is large, and there has been a problem that satisfactory transistor characteristics cannot obtained particularly in P-channel MIS transistors. In addition, a high-dielectric-constant thin film formed using the ALD method generally contains several percent impurities. This is considered because carbon (C), hydrogen (H) or chlorine (Cl) included in material gas using the ALD method remains and is incorporated in the formed film. The impurities remaining in the high-dielectric-constant film may cause fixed charge and trap, and the characteristics of the film is damaged. | <SOH> SUMMARY OF THE INVENTION <EOH>The one object of the present invention is to restrict initial Vfb shift, to form a gate insulating film having high film quantity, and to achieve satisfactory transistor characteristics. Another object of the present invention is to lower the impurity content in the high-dielectric-constant film of the gate insulating film. According to one aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film and a gate electrode. The gate insulating film is formed on the substrate, and has a nitrogen-containing metal silicate film or a nitrogen-containing metal aluminate film that contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less on the uppermost layer. The gate electrode is formed on the gate insulating film. Another aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film, and a gate electrode. The gate insulating film is formed on the substrate and has a base interface layer, a metal silicate film and a nitrogen-containing metal silicate film. The base interface layer is formed on the substrate. The metal silicate film is formed on the base interface layer, and contains a metal, oxygen and silicon. The nitrogen-containing metal silicate film contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less, oxygen, silicon, and nitrogen. The gate electrode formed on the gate insulating film. Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the upper layer of the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicatefilm containing a metal in a peak concentration of 5 atomic % or more and 40 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less and nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. Another aspect of the present invention, a apparatus for forming a film comprises a housing, a table installed in the housing, for placing a substrate, a gas supply port for supplying a gas into the housing, a gas discharge port for discharging the gas in the housing out of the housing, and a heater. The heater is for heating the surface of the substrate by radiating light on the surface of the substrate placed on the table for a time up to several milliseconds. Another aspect of the present invention, in a method for forming a high-dielectric-constant film on a substrate, a first material gas that contains at least one element in elements constituting the high-dielectric-constant film is supplied into a housing wherein the substrate is placed. A second material gas that reacts with the first material gas and forms the high-dielectric-constant film is supplied into the housing. The surface of the substrate is heated by radiating light onto the surface of the substrate for a time up to several milliseconds. Other and further objects, features and advantages of the invention will appear more fully from the following description. | 20040330 | 20060905 | 20050630 | 62575.0 | 0 | PHAM, LONG | METHOD FOR MANUFACTURING A SEMICONDUCTOR DEVICE AND METHOD FOR FORMING HIGH-DIELECTRIC-CONSTANT FILM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,042 | ACCEPTED | Headphoning | A noise reducing headset has one or more of the following features: (a) pair of earcups each seated in a yoke assembly mechanically coupled by a headband enclosing a flat spring formed with a slot that runs the length of the spring accommodating electrical wires electrically interconnecting electrical elements in the earcups, (b) each earcup having active noise reducing circuitry, (c) each earcup including a loudspeaker driver located off center in the earcup to allow an internal cavity inside each earcup to accommodate a loudspeaker driver, a microphone and an electronic printed circuit board and one of a battery and plug assembly, (d) one of the earcups accommodating a detachably secured plug assembly having a sensitivity switch covered by the earcup when the plug assembly is fully seated in the earcup, (e) the other earcup having a battery door that may be opened to allow insertion and removal of the battery and covered by a yoke assembly when the headset is worn by a user with the battery fully seated in the earcup. | 1. A noise reducing headset comprising, a pair of earcups each having electrical elements and seated in a yoke assembly mechanically coupled by a headband enclosing a flat spring formed with a slot that runs the length of the spring accommodating electrical wires electrically interconnecting electrical elements in the earcups, each earcup having active noise reducing circuitry, each earcup including a loudspeaker driver located off center in the earcup to allow an internal cavity inside each earcup to accommodate the loudspeaker driver, a microphone and an electronic printed circuit board and one of a battery and plug assembly, one of said earcups accommodating a detachably secured plug assembly having a sensitivity switch covered by the earcup when the plug assembly is fully seated in the earcup, the other earcup having a battery door that may be opened to allow insertion and removal of the battery and covered by a yoke assembly when the headphones are worn by a user with the battery fully seated in the earcup. 2. A noise reducing headset in accordance with claim 1 and further comprising plastic covering said slot with the wires therein. 3. A noise reducing headset in accordance with claim 1 and further comprising a circumaural cushion attached to each earcup constructed and arranged to surround the ear of a user. 4. A headset comprising, a pair of earcups having electrical elements: each seated in a yoke assembly mechanically coupled by a headband enclosing a flat spring formed with a slot that runs the length of the spring accommodating electrical wires electrically interconnecting electrical elements in the earcups. 5. A noise reducing headset comprising, a pair of earcups, each earcup including a loudspeaker driver located off center in the earcup to allow an internal cavity inside each earcup to accommodate said loudspeaker driver, a microphone and an electronic printed circuit board and one of a battery and plug assembly. 6. A noise reducing headset in accordance with claim 5 and further comprising, said microphone and said electronic printed circuit board inside said cavity. 7. A noise reducing headset having an earcup attached to a yoke assembly comprising, said earcup having a battery door that may be opened to allow insertion and removal of a battery and covered by said yoke assembly when the headset is worn by a user with the battery fully seated in the earcup. | The present invention relates in general to headphoning and more particularly concerns novel headphones especially advantageous in connection with active noise reducing but having features useful in passive headphones. A headset is a pair of headphones interconnected by a headband. BACKGROUND OF THE INVENTION For background, reference is made to U.S. Pat. Nos. 6,597,792, 5,305,387, 5,208,268, 5,181,252, 4,989,271, 4,922,542, 4,644,581 and 4,455,675. Reference is also made to the commercially available Bose QUIET COMFORT headset and the commercially available QUIET COMFORT 2 headphones. The QUIET COMFORT 2 headphones embody the invention disclosed herein and is incorporated by reference herein. SUMMARY OF THE INVENTION According to aspects of the invention, an active noise reducing headset is constructed and arranged with a replaceable battery in one earcup and a detachably securable plug having a switch and an audio cable with a plug at the end for mating engagement with a sound source jack in the other earcup. Both earcups have active noise reduction circuitry. Another feature of the invention is an enclosed headband spring embracing an electrical cable that intercouples electrical elements in the respective earcups. Still another feature of the invention is a loudspeaker driver offset from the center of the earcup adjacent to a printed circuit board carrying circuitry. Still another feature of the invention is a hinged battery access door that when closed is normally covered by the yoke arm assembly that pivotally supports the earcup. Other features, objects and advantages of the invention will become apparent from the following detailed description when read in connection with the accompanying drawing, in which: BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING FIG. 1 is a perspective view of a commercially available Bose QUIET COMFORT 2 headphones embodying the invention; FIG. 2 is a side pictorial view illustrating a feature of the headband cable covered between two sections of flat spring; FIG. 3 is a pictorial view of an earcup according to the invention showing a feature of the loudspeaker driver off center; FIG. 4 is a diagrammatic cross-section through an earcup showing the feature of small earcup profile with space for the ear and internal components; FIG. 5 is a pictorial view of an earcup illustrating the feature of the plug assembly with switch hidden; FIG. 6 is a pictorial view of an earcup yoke assembly showing the feature of the battery door on top protected by the headband yoke with the battery door open; FIG. 7 is a pictorial view of an earcup yoke assemby showing the feature of the battery door on top protected by the headband yoke with the battery door closed; and FIG. 8 is a pictorial view showing the plug assembly with switch removed from the earcup. DETAILED DESCRIPTION With reference now to the drawing, and more particularly to FIG. 1 thereof, there is shown a perspective view of a commercially available Bose QUIET COMFORT 2 headphones embodying the invention. The headphones include a right earcup 11 and a left earcup 12 intercoupled by a headband 13 with a depending right yoke assembly 14 and left yoke assembly 15. The right earcup 11 includes a switch 16 and an LED 17 that is illuminated when switch 16 is in the on position. Right earcup 11 and left earcup 12 include right circumaural cushion 21 and circumaural left cushion 22, respectively. Referring to FIG. 2, there is shown a pictorial view illustrating the feature of the headband cable 22 interconnecting electrical elements in the earcups covered between sections 23A and 23B of a flat spring that furnishes a clamping force to keep the earcups over the ears of a user. The interconnected electrical elements may comprise switch 16 and an electronic circuit board 32 in left earcup 12, and battery 37 in right earcup 11 (FIG. 4). The same reference symbols identify corresponding elements throughout the drawing. Referring to FIG. 3, there is shown a pictorial view illustrating the feature of loudspeaker driver 31 mounted off-center in the earcup. Printed circuit board 32 is mounted above loudspeaker 31 in left earcup 12 that includes a detachably secured connector 33 with appended cord 34 having a miniature stereo plug (not shown) at the other end for engagement with a mating jack that is connected to a source of audio signals, such as the sound channels in an aircraft or a CD player. Referring to FIG. 4, there is shown a diagrammatic cross section through an earcup showing the compact earcup profile formed with space for the ear and internal components. Each earcup includes a loudspeaker driver 31 positioned as shown, a microphone 35 positioned as shown, an electronics printed circuit board 32 as shown, a plug assembly in left earcup 12 and a battery 37 in right earcup 11 positioned as shown with the ear 36 accommodated and surrounded by a circumaural ear cushion 21, 22. Referring to FIG. 5, there is shown a pictorial view of left earcup 12 illustrating the location of plug assembly 33 that carries a high-low switch and is detachably secured to the earcup allowing relatively easy removal to select the switch position or to remove the cord when only noise reducing is desired so that the user may then move about while wearing the headphones illustrated in FIG. 1. Referring to FIG. 6, there is shown a view of an earcup and yoke arm assembly illustrating how battery 37 is removably seated in earcup 11 with battery access door 41 in the open position. When battery 37 is fully inserted, battery access door 41 closes and is covered by yoke arm assembly 14 when the headphones are positioned on the head of a user with earcups embracing the ears. Referring to FIG. 7, there is shown the assembly of FIG. 6 with battery access door 41 closed and covered by yoke arm assembly 14. Referring to FIG. 8, there is shown a view of left earcup 12 with plug assembly 33 removed to illustrate how sensitivity switch 33A is positioned to switch in a resistor for lower sensitivity and switch out the resistor for higher sensitivity (resistor not shown) and section 33B that smoothly covers the opening when plug assembly 33 is fully seated in earcup assembly 12. The invention has a number of advantages. Locating the battery door on the top of an earcup makes it difficult for a battery to inadvertently fall from the cup with the yoke over the battery door when the headphones are in use for the battery door cannot open. The flat spring for providing clamping force provides a desired clamping force while keeping the width and weight of the spring low. A slot that runs the length of the headband spring conveniently accommodates the wires interconnecting the earcups and may be covered by a protective plastic. The earcups have a relatively small profile while furnishing desired cavity volumes by vertically orienting the battery and attenuator/plug assembly and locating them forward in the earcups such that they are located in a region where there is no intrusion into the front cavity by the user's pinna. When the plug/attenuator assembly is inserted into the earcup, the switch available to control the volume or sensitivity of the headset is covered and not directly accessible by the user where it might be inadvertently switched to a different position. The loudspeaker drivers are offset from the center of the earcup and are located lower in the cup (although higher may be used). Using a round driver in a substantially round earcup and offsetting the driver towards one end or the other allows more room for location of a printed circuit board. It is evident that those skilled in the art may now make numerous uses and modifications of and departures from the specific apparatus and techniques described herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques herein disclosed and limited only by the spirit and scope of the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>For background, reference is made to U.S. Pat. Nos. 6,597,792, 5,305,387, 5,208,268, 5,181,252, 4,989,271, 4,922,542, 4,644,581 and 4,455,675. Reference is also made to the commercially available Bose QUIET COMFORT headset and the commercially available QUIET COMFORT 2 headphones. The QUIET COMFORT 2 headphones embody the invention disclosed herein and is incorporated by reference herein. | <SOH> SUMMARY OF THE INVENTION <EOH>According to aspects of the invention, an active noise reducing headset is constructed and arranged with a replaceable battery in one earcup and a detachably securable plug having a switch and an audio cable with a plug at the end for mating engagement with a sound source jack in the other earcup. Both earcups have active noise reduction circuitry. Another feature of the invention is an enclosed headband spring embracing an electrical cable that intercouples electrical elements in the respective earcups. Still another feature of the invention is a loudspeaker driver offset from the center of the earcup adjacent to a printed circuit board carrying circuitry. Still another feature of the invention is a hinged battery access door that when closed is normally covered by the yoke arm assembly that pivotally supports the earcup. Other features, objects and advantages of the invention will become apparent from the following detailed description when read in connection with the accompanying drawing, in which: | 20040329 | 20080812 | 20050929 | 99926.0 | 1 | ENSEY, BRIAN | HEADPHONING | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,084 | ACCEPTED | Method of storing and supplying hydrogen to a pipeline | A method of storing and supplying a gaseous hydrogen product to a pipeline under a product purity specification in which a hydrogen stream made up of gaseous hydrogen is compressed to form a compressed hydrogen stream and introduced into a salt cavern for storage. A crude hydrogen stream, contaminated from storage in the salt cavern is recovered and purified by sufficiently removing at least carbon dioxide and water vapor to produce a hydrogen product stream having an impurity level at or below the product purity specification. The hydrogen product stream is supplied back to the pipeline. Alternatively, during periods of low demand, hydrogen produced by a production facility is both purified and supplied to the pipeline and stored in the salt cavern. During high demand period, both the output of the production facility and hydrogen retrieved from the salt cavern are purified and supplied to the pipeline. | 1. A method of storing and supplying a gaseous hydrogen product to a pipeline under a product purity specification, said method comprising: compressing a hydrogen stream made up of gaseous hydrogen to form a compressed hydrogen stream; introducing the compressed hydrogen stream into a salt cavern for storage of the gaseous hydrogen; recovering a crude hydrogen stream from the salt cavern; purifying the crude hydrogen stream by sufficiently removing at least carbon dioxide and water vapor from the crude hydrogen stream to at least in part produce a hydrogen product stream having an impurity level of the carbon dioxide and water vapor at or below the product purity specification; and supplying the gaseous hydrogen product to the pipeline by introducing said hydrogen product stream into said pipeline. 2. The method of claim 1, wherein: the gaseous hydrogen is produced by a hydrogen production facility having a hydrogen plant configured to produce the gaseous hydrogen with a higher impurity level of the carbon dioxide and water vapor than the product purity specification and purification equipment configured to purify the gaseous hydrogen to directly produce the hydrogen product stream and to purify the crude hydrogen stream to produce the hydrogen product stream therefrom; and when demand for the gaseous hydrogen product is below a production capacity of the hydrogen plant, the hydrogen product stream is formed by directly purifying part of the gaseous hydrogen without recovery of the crude hydrogen stream from the salt cavern and utilizing a remaining part of the gaseous hydrogen as the hydrogen stream for compression and storage in the salt cavern; and when demand for the gaseous hydrogen product is above the production capacity of the hydrogen plant, the crude hydrogen stream is recovered from the salt cavern and purified to at least in part to produce the product stream. 3. The method of claim 1, wherein: the hydrogen stream is removed from the pipeline and stored within the salt cavern during periods of low demand for the hydrogen product; and the hydrogen product stream is introduced into the pipeline during periods of high demand for the hydrogen product. 4. The method of claim 1, wherein: the crude hydrogen stream is purified by also sufficiently removing hydrogen sulfide; the product purity specification contains predetermined concentrations of hydrogen sulfide, water vapor and carbon dioxide; water in a liquid state and other contaminants are removed from the crude hydrogen stream within a coalescing filter; the hydrogen sulfide, water vapor and the carbon dioxide are removed from the crude hydrogen stream after the coalescing filter by adsorption; and the hydrogen sulfide is removed before the water vapor and the carbon dioxide. 5. The method of claim 4, wherein: the hydrogen sulfide is removed within a hydrogen sulfide adsorption bed to form an intermediate product stream; and the intermediate product stream is introduced into a system of adsorbent beds configured to remove the carbon dioxide and water in an alternating fashion such that one bed is online producing the hydrogen product stream while another bed is an off-line bed being regenerated through desorption. 6. The method of claim 5, wherein: the system of adsorbent beds are operated in accordance with a temperature swing adsorption cycle; a subsidiary hydrogen product stream is divided out of the hydrogen product stream and is heated; the subsidiary hydrogen product stream is introduced into the off-line adsorbent bed, thereby to produce a regeneration stream containing desorbed impurities; water is separated from the regeneration stream; and after water separation, the regeneration stream is compressed and recycled back to the coalescing filter. 7. The method of claim 1, wherein the hydrogen stream is compressed to about 2200 psig and the hydrogen product stream is reduced in pressure to between about 600 psig and about 800 psig. 8. The method of claim 1, wherein the product purity specification of the hydrogen product stream is about 99.99 percent pure hydrogen containing less than about 100 ppmv nitrogen and argon, less than about 1 ppmv of carbon monoxide and carbon dioxide, less than about 1 ppmv methane, less than about 1 ppmv water, and less than about 1 ppmv hydrogen sulfide. | FIELD OF THE INVENTION The present invention relates to a method of storing and supplying a gaseous hydrogen product to a pipeline in which gaseous hydrogen is stored in a salt cavern for later use. More particularly, the present invention relates to such a method in which gaseous hydrogen stored in the salt cavern is purified so that it can be supplied to the pipeline under a product purity specification. BACKGROUND OF THE INVENTION Hydrogen can be supplied to customers connected to a hydrogen pipeline. Typically, the hydrogen is manufactured by steam methane reforming in which a hydrocarbon and steam are reacted at high temperature in order to produce a synthesis gas containing hydrogen and carbon monoxide. Hydrogen is separated from the synthesis gas to produce a hydrogen product that is introduced into the pipeline for distribution to the customers. Alternatively, hydrogen can be recovered from a hydrogen rich stream. Typically, hydrogen is supplied to customers under agreements that require availability and on stream times for the steam methane reformer or hydrogen recovery plant. When a steam methane reformer is taken off-line for unplanned or extended maintenance, the result could be a violation of such agreements. Additionally, there are times in which customer demand can exceed hydrogen production capacity of existing plants. A storage capacity for the pipeline hydrogen or a sufficient backup is therefore very desirable in connection with hydrogen pipeline operations. However, providing a backup for hydrogen supply practically requires a large volume of hydrogen to be stored in above ground gaseous storage receivers or liquid storage tanks. The construction costs involved make such a backup storage capacity impractical. The problem is particularly exacerbated where the hydrogen is supplied under pipeline product specification that require a hydrogen purity typically above 95% and possibly of 99.99% for ultra high purity hydrogen. Practically speaking, considering that hydrogen production plants on average have production capacities that are roughly 50 million standard cubic feet per day, a storage capacity for hydrogen that would allow a plant to be taken off-line be in the order of 1 billion standard cubic feet. Hydrogen as well as other gases have been stored in salt caverns. Salt caverns are large underground voids that are formed by solution mining of salt as brine. Caverns are common in gulf states of the United States where demand for hydrogen is particularly high. Such hydrogen storage has only taken place where there are no purity requirements placed upon the hydrogen product. As such, contamination of the hydrogen from being stored in a salt formation is an unknown variable. As will be discussed, inventors herein have identified the problem of increased contamination of hydrogen storage in salt caverns and have remedied contamination in accordance with the present invention in order to allow hydrogen stored within salt cavern to be delivered to a pipeline when needed under product purity specifications. SUMMARY OF THE INVENTION The present invention provides a method of storing and supplying a gaseous hydrogen product to a pipeline under a product purity specification. In accordance with the method, a hydrogen stream made up of gaseous hydrogen is compressed to form a compressed hydrogen stream. The compressed hydrogen stream is introduced into a salt cavern for storage of the gaseous hydrogen. A crude hydrogen stream is recovered from the salt cavern and then purified by sufficiently removing at least carbon dioxide and water vapor from the crude hydrogen stream to at least in part produce a hydrogen product stream having an impurity level at or below the product purity specification. The gaseous hydrogen product is supplied to the pipeline by introducing the hydrogen product stream into the pipeline. As will be discussed it has been found by the inventors herein that storage of hydrogen within salt formation produces unacceptably high levels of carbon dioxide and potentially other impurities in the hydrogen. Purification of the hydrogen stream from such impurities allows it to be delivered at any desired product specification. The gaseous hydrogen can be produced by a hydrogen production facility, such as a steam methane reformer, that is configured to produce the gaseous hydrogen with a higher level of the carbon dioxide and water vapor than the product purity specification. Purification equipment is provided to purify the gaseous hydrogen to directly produce the hydrogen product stream and also to purify the crude hydrogen stream to produce the hydrogen product stream therefrom. When the demand for the gaseous hydrogen product is below a production capacity of the hydrogen plant, the hydrogen product stream is formed by directly purifying part of the gaseous hydrogen without recovery of the crude hydrogen stream from the salt cavern. The remaining part of the gaseous hydrogen is utilized as a hydrogen stream for compression and storage in the salt cavern. When demand for the gaseous product is above the production capability of the hydrogen plant, the crude hydrogen stream can be recovered from the salt cavern and purified to at least in part produce the product stream. Alternatively, the hydrogen stream for storage can be directly removed from the pipeline and stored during periods of low demand for the hydrogen product. If the demand intensifies due to either a reduced production capability, for instance, a plant being taken off-line for maintenance or a high customer demand, the hydrogen product stream can be supplied from the salt cavern and introduced into the pipeline. As mentioned above, other impurities may be present in a product specification such as hydrogen sulfide. In such case, water in a liquid state and other contaminants can be removed from the crude hydrogen stream within a coalescing filter. The hydrogen sulfide, water vapor and carbon dioxide can be removed from the crude hydrogen stream after the coalescing filter by adsorption. In such case the hydrogen sulfide is removed before the water vapor and carbon dioxide. The hydrogen sulfide can be removed within a hydrogen sulfide adsorption bed to form an intermediate product stream. The intermediate product stream can be introduced into a system of adsorbent beds that are configured to remove the carbon dioxide and water in an alternating fashion such that one bed is on line producing the hydrogen product stream while another bed is off-line being regenerated through desorption. The system of adsorbent beds can be operated in accordance with the temperature swing adsorption cycle. A subsidiary hydrogen product stream can be divided out of the hydrogen product stream and heated. After heating the subsidiary hydrogen product stream can be introduced into the off-line adsorption bed, thereby to produce a regeneration stream containing desorbed impurities. Water can be separated from the regeneration stream and after water separation, the regeneration stream can be compressed and recycled back to the coalescing filter. The hydrogen stream to be stored can be compressed to about 2200 psig and the hydrogen product stream to be supplied to the pipeline can be reduced in pressure to between about 600 psig and about 800 psig. The hydrogen purity product specification can be about 99.99% pure hydrogen that contains less than about 100 ppmv of nitrogen and argon, less than 1 ppmv of carbon monoxide and carbon dioxide, less than 1 ppmv of methane, less than 1 ppmv of water and less than about 1 ppmv of hydrogen sulfide. BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims distinctly pointing out the subject matter that Applicants regard as their invention, it is believed that the invention will be better understood when taken in connection with the accompanying drawings in which: FIG. 1 is a schematic illustration of a process flow diagram illustrating the flow of various hydrogen streams in connection with an apparatus carrying out a method in accordance with the present invention; FIG. 2 is an alternative embodiment of a process flow diagram illustrating the flow of various hydrogen streams in connection with an apparatus for carrying out a method in accordance with the present invention; and FIG. 3 is a purification system that can be utilized in carrying out a method in accordance with the present invention. DETAILED DESCRIPTION With reference to FIG. 1, a gaseous hydrogen product stream 10 is introduced into a pipeline 12 for distribution of hydrogen to customers 14, 16 and 18. Hydrogen is supplied to pipeline 12 by way of hydrogen generation facilities designated by reference numbers 20, 22, 26 and 28. Hydrogen for such pipeline may have a product purity specification of 99.99 mol % hydrogen in which the hydrogen contains less than 100 ppmv of nitrogen and argon, less than 1 ppmv of carbon monoxide and carbon dioxide, and less than 1 ppmv of methane, water vapor and hydrogen sulfide. Such a pipeline would therefore be capable of supplying high purity hydrogen under the aforesaid product purity specification. It also is possible that the product specification might have a lower product purity specification in which higher levels of impurities such as hydrogen sulfide would be tolerated. During periods of low demand by customers 14, 16 and 18 or at least during periods when excess production capacity of hydrogen generation facilities 20, 22, 26 and 28 exist, a gaseous hydrogen stream 30 is removed from a pipeline 12 and compressed to about 2200 psig by a cavern feed compressor 32 to produce a compressed hydrogen stream 34 that is stored within a salt cavern 36. When a hydrogen generation facility, such as that designated by reference number 20, is taken off-line for any reason or when demand for hydrogen by customers 14, 16 and 18 exceeds the available production capabilities, hydrogen is removed from salt cavern 36 as a crude hydrogen stream 40 and purified within purification system 38. The purification of crude hydrogen stream 40 produces hydrogen product stream 10 which is reintroduced into pipeline 12. Hydrogen product stream 10 may have a pressure of between about 600 psig and about 800 psig. It is to be noted, that storage within salt cavern 36 can introduce carbon dioxide into the hydrogen due to equilibrium with dissolved CO2. The brine has dissolved carbon dioxide which may off gas to the stored hydrogen. The stored gaseous hydrogen will be in contact with brine and therefore the level of moisture introduced into the stored hydrogen may be unacceptable. As mentioned above, carbon dioxide and water vapor may be the only significant impurities that could be effected by storage in the salt cavern 36 and other impurities within the product purity specification would be unchanged by such storage. Hydrogen sulfide may be a significant impurity in the product purity specification. However, it is not completely understood whether salt cavern storage would have an effect on such an impurity. However, cavern brine is an aqueous solution containing salt ions, including sulfates and carbonates. The high partial pressure of hydrogen within salt cavern 36 could reduce sulfate ions to hydrogen sulfide or bacterial activity could generate H2S and therefore storage of gaseous hydrogen within salt cavern 36 could result in an unacceptable level of hydrogen sulfide to be returned to pipeline 12. As such, even though the hydrogen taken from pipeline 10 may be at high purity, after storage, the possibility exists that carbon dioxide and water vapor levels will rise to unacceptable high levels with respect to the product purity specification. The same possibility exists for hydrogen sulfide when applicable. Other impurities within the product purity specification will remain unaffected by storage. With reference to FIG. 2, salt cavern 36 and a hydrogen production facility 22 can be placed in close proximity to one another. Hydrogen generation facility 22 contains a hydrogen plant to produce a gaseous hydrogen product with a higher impurity level of at least carbon dioxide and water vapor than is required for the product purity specification and possibly also and hydrogen sulfide if applicable. Other hydrogen generation facilities 20, 26 and 28 can be provided to supply gaseous hydrogen to pipeline 12 under product purity specifications requiring specific concentrations of impurities such as carbon dioxide, water and hydrogen sulfide. As such, the hydrogen generation facilities 20, 26 and 28 are provided with purification equipment to allow hydrogen to be supplied under the specification. When excess hydrogen generation capacity exists, part of the gaseous hydrogen product, as a gaseous hydrogen stream 41, is introduced into an on-site, final purification system 38′ to acceptably reduce carbon dioxide, water vapor and hydrogen sulfide levels to meet the product purity specification. Other purification equipment would be included within hydrogen production facility 22 to meet remaining component impurity requirements in the product specification. At such time, a remaining part of the gaseous hydrogen product, as a gaseous hydrogen stream 42, would be compressed by cavern feed compressor 32 and stored within salt cavern 36 by way of compressed hydrogen stream 34. When demand of gaseous hydrogen product is above the production capacity along pipeline 12, crude hydrogen stream 40 is recovered from the salt cavern 36 and is combined with a gaseous hydrogen stream 41 to produce a combined stream that is sent to purification system 38′ to form product stream 10. Hence, the purification system 38′ functions both to purify the hydrogen from the hydrogen production facility 22, for instance, a steam methane reformer, and the hydrogen stored in salt cavern 36. As such, the hydrogen stored in salt cavern 36 is stored at low purity for later purification within purification system 38′. The embodiment of FIG. 2 allows dual use for final purification system 38′ to function for both hydrogen production facility 22 and hydrogen retrieved from salt cavern 36. This obviates the need to fabricate a separate purification facility dedicated to salt cavern 36. A further modification to such embodiment would be to couple hydrogen production facility 22 and salt cavern 36 to all purification used in connection with hydrogen production facility 22. With reference to FIG. 3, hydrogen purification system 38 is illustrated in a form that is capable of purifying gaseous hydrogen stored in salt cavern 36 from such contaminants as carbon dioxide, water vapor and hydrogen sulfide. Though the potential for hydrogen sulfide contamination from storage within salt cavern 36 is not known, it is seen as a safeguard from potential contamination that would result in an expensive loss of product if such contamination were to occur. The same design could be used for hydrogen purification system 38′. As may be appreciated, if hydrogen sulfide contamination were not in issue due to the product purity specification, hydrogen sulfide purification would be eliminated from the purification system. Gaseous hydrogen stream 30 (shown in FIG. 1) is removed from pipeline 12 through a conduit 46 having an isolation valve 48 to isolate hydrogen purification system 38 from pipeline 12 for maintenance purposes. In the following discussion, the control valves are normally in a closed position, cutting off the flow and can be remotely operated valves which are centrally and electronically controlled. If hydrogen is to be stored, control valve 50 is set in an open position. A control valve 52 is also set in an open position to allow the gaseous hydrogen stream 30 to be fed to feed compressor 32 and aftercooler 54. Aftercooler 54 is a known device consisting of a heat exchanger utilizing cooling water and a draft fan to remove the heat of compression from stream 30 (shown in FIG. 1). The resultant compressed hydrogen stream 34 (shown in FIG. 1) flows within conduit 56 to salt cavern 36. Control valves 58 and 60 are set in open positions open during this time of storage. As illustrated, salt cavern 36 is of conventional design having a brine string 62 exhausting into a brine pond and a metal casing held in place by a concrete lining 64. After storage is complete, the aforementioned valves are returned to their normally closed condition. When production is to be supplemented with hydrogen stored in salt cavern 36, control valve 60 is set in an open position to allow the supply of the hydrogen product stream 10 (shown in FIG. 1) to pipeline 12. The opening of control valve 60 allows crude hydrogen stream 40 (shown in FIG. 1) to flow from salt cavern 36 through conduit 68. Pressure is controlled within conduit 68 by pressure transducers 70 and 72 and a controller 74 that operates proportional control valve 76. The crude hydrogen stream 40 then enters a coalescing filter 78 of known design in which water is removed. Hydrogen sulfide is removed by a hydrogen sulfide removal bed 80 which can utilize a zinc oxide catalytic adsorbent. In practice, bed 80 is never regenerated. It is simply replaced on a periodic maintenance schedule. The crude hydrogen stream 40 then enters a temperature swing adsorption unit 82 as an intermediate product stream having adsorbent beds 84 and 86 to remove carbon dioxide and water therefrom. The hydrogen product stream 10 (shown in FIG. 1) resulting from the purification of the crude hydrogen stream 40 is then routed through outlet conduit 88. Pressure transducers 90, 92 connected to a controller 94 are used to control pressure within outlet conduit 88 through a proportional control valve 96. Hydrogen product stream 10 flows through conduit 46 and back to pipeline 12. As can be appreciated during this period of supply, control valve 52 is set in a closed position and control valve 50 is set in an open position. Adsorption beds 84 and 86 are operated in accordance with a temperature swing adsorption cycle which one bed is online producing the hydrogen product stream while the other bed is an off-line bed and is being regenerated. For regeneration purposes, a regeneration conduit 98 is provided having a regeneration heater 100 which is controlled by a temperature transducer 102 and a controller 104. A subsidiary hydrogen product stream, composed of part of the hydrogen product stream, is introduced to the off-line adsorption bed, either bed 84 or 86. The high temperature of the subsidiary hydrogen product stream causes desorption of carbon dioxide and water which is discharged from the bed being regenerated as a heated regeneration stream having increased concentrations of the desorbed carbon dioxide and water. Such heated regeneration stream is then cooled within a regeneration cooler 106 which can be a water cooled heat exchanger in which a forced draft is produced by a draft fan. After the cooling of the heated regeneration stream, the resultant cooled stream is then sent to a regeneration separator 108 which is simply a pot to allow water produced by cooling within regeneration cooler 106 to discharge as a stream 110. During regeneration, valve 112 is set in an open position to allow such stream to be compressed by feed compressor 32 and cooled by aftercooler 54. Further, valve 58 is set in a closed position and a valve 114 is set in an open position to allow the resultant cooled, dried stream to combine with crude hydrogen stream flowing in conduit 68 for subsequent carbon dioxide and water removal. As can be appreciated, the recirculation of the regeneration stream will eventually concentrate impurities within the purification system. In order to avoid this, at specific time periods, valve 112 is set in a closed position and valve 116 is reset in the open position to discharge the heated regeneration stream after having been cooled in regeneration cooler 106. The purging can be on a continual basis as well. Valve 112 could be open and valve 116 could be partially opened. The degree to which valve 116 is open would be chosen to achieve a certain impurity level. A higher percentage of openness would lead to a lower impurity level (fewer impurities), and a lower percentage of openness would lead to a higher impurity level (more impurities). As may be appreciated, it is possible to use other cycles for regeneration for adsorbent beds. For instance, the adsorbent beds could function on a pressure swing adsorption cycle. Moreover, membrane and cryogenic distillation devices could be used in place of adsorbent systems. While the present invention has been described with reference to a preferred embodiment, as will be understood by those skilled in the art, numerous changes, omissions and additions can be made without departing from the spirit and the scope of the present invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>Hydrogen can be supplied to customers connected to a hydrogen pipeline. Typically, the hydrogen is manufactured by steam methane reforming in which a hydrocarbon and steam are reacted at high temperature in order to produce a synthesis gas containing hydrogen and carbon monoxide. Hydrogen is separated from the synthesis gas to produce a hydrogen product that is introduced into the pipeline for distribution to the customers. Alternatively, hydrogen can be recovered from a hydrogen rich stream. Typically, hydrogen is supplied to customers under agreements that require availability and on stream times for the steam methane reformer or hydrogen recovery plant. When a steam methane reformer is taken off-line for unplanned or extended maintenance, the result could be a violation of such agreements. Additionally, there are times in which customer demand can exceed hydrogen production capacity of existing plants. A storage capacity for the pipeline hydrogen or a sufficient backup is therefore very desirable in connection with hydrogen pipeline operations. However, providing a backup for hydrogen supply practically requires a large volume of hydrogen to be stored in above ground gaseous storage receivers or liquid storage tanks. The construction costs involved make such a backup storage capacity impractical. The problem is particularly exacerbated where the hydrogen is supplied under pipeline product specification that require a hydrogen purity typically above 95% and possibly of 99.99% for ultra high purity hydrogen. Practically speaking, considering that hydrogen production plants on average have production capacities that are roughly 50 million standard cubic feet per day, a storage capacity for hydrogen that would allow a plant to be taken off-line be in the order of 1 billion standard cubic feet. Hydrogen as well as other gases have been stored in salt caverns. Salt caverns are large underground voids that are formed by solution mining of salt as brine. Caverns are common in gulf states of the United States where demand for hydrogen is particularly high. Such hydrogen storage has only taken place where there are no purity requirements placed upon the hydrogen product. As such, contamination of the hydrogen from being stored in a salt formation is an unknown variable. As will be discussed, inventors herein have identified the problem of increased contamination of hydrogen storage in salt caverns and have remedied contamination in accordance with the present invention in order to allow hydrogen stored within salt cavern to be delivered to a pipeline when needed under product purity specifications. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a method of storing and supplying a gaseous hydrogen product to a pipeline under a product purity specification. In accordance with the method, a hydrogen stream made up of gaseous hydrogen is compressed to form a compressed hydrogen stream. The compressed hydrogen stream is introduced into a salt cavern for storage of the gaseous hydrogen. A crude hydrogen stream is recovered from the salt cavern and then purified by sufficiently removing at least carbon dioxide and water vapor from the crude hydrogen stream to at least in part produce a hydrogen product stream having an impurity level at or below the product purity specification. The gaseous hydrogen product is supplied to the pipeline by introducing the hydrogen product stream into the pipeline. As will be discussed it has been found by the inventors herein that storage of hydrogen within salt formation produces unacceptably high levels of carbon dioxide and potentially other impurities in the hydrogen. Purification of the hydrogen stream from such impurities allows it to be delivered at any desired product specification. The gaseous hydrogen can be produced by a hydrogen production facility, such as a steam methane reformer, that is configured to produce the gaseous hydrogen with a higher level of the carbon dioxide and water vapor than the product purity specification. Purification equipment is provided to purify the gaseous hydrogen to directly produce the hydrogen product stream and also to purify the crude hydrogen stream to produce the hydrogen product stream therefrom. When the demand for the gaseous hydrogen product is below a production capacity of the hydrogen plant, the hydrogen product stream is formed by directly purifying part of the gaseous hydrogen without recovery of the crude hydrogen stream from the salt cavern. The remaining part of the gaseous hydrogen is utilized as a hydrogen stream for compression and storage in the salt cavern. When demand for the gaseous product is above the production capability of the hydrogen plant, the crude hydrogen stream can be recovered from the salt cavern and purified to at least in part produce the product stream. Alternatively, the hydrogen stream for storage can be directly removed from the pipeline and stored during periods of low demand for the hydrogen product. If the demand intensifies due to either a reduced production capability, for instance, a plant being taken off-line for maintenance or a high customer demand, the hydrogen product stream can be supplied from the salt cavern and introduced into the pipeline. As mentioned above, other impurities may be present in a product specification such as hydrogen sulfide. In such case, water in a liquid state and other contaminants can be removed from the crude hydrogen stream within a coalescing filter. The hydrogen sulfide, water vapor and carbon dioxide can be removed from the crude hydrogen stream after the coalescing filter by adsorption. In such case the hydrogen sulfide is removed before the water vapor and carbon dioxide. The hydrogen sulfide can be removed within a hydrogen sulfide adsorption bed to form an intermediate product stream. The intermediate product stream can be introduced into a system of adsorbent beds that are configured to remove the carbon dioxide and water in an alternating fashion such that one bed is on line producing the hydrogen product stream while another bed is off-line being regenerated through desorption. The system of adsorbent beds can be operated in accordance with the temperature swing adsorption cycle. A subsidiary hydrogen product stream can be divided out of the hydrogen product stream and heated. After heating the subsidiary hydrogen product stream can be introduced into the off-line adsorption bed, thereby to produce a regeneration stream containing desorbed impurities. Water can be separated from the regeneration stream and after water separation, the regeneration stream can be compressed and recycled back to the coalescing filter. The hydrogen stream to be stored can be compressed to about 2200 psig and the hydrogen product stream to be supplied to the pipeline can be reduced in pressure to between about 600 psig and about 800 psig. The hydrogen purity product specification can be about 99.99% pure hydrogen that contains less than about 100 ppmv of nitrogen and argon, less than 1 ppmv of carbon monoxide and carbon dioxide, less than 1 ppmv of methane, less than 1 ppmv of water and less than about 1 ppmv of hydrogen sulfide. | 20040330 | 20060718 | 20051006 | 63662.0 | 1 | LANGEL, WAYNE A | METHOD OF STORING AND SUPPLYING HYDROGEN TO A PIPELINE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,173 | ACCEPTED | User interface display apparatus using texture mapping method | A low cost user interface display system, like on screen display (OSD), using texture mapping method is presented. The present invention only uses a little texture memory and can generate very fancy user interface display. With the method of texture mapping, even the low cost system can have a colorful, fancy user interface display. A user interface display apparatus using texture-mapping method, comprising a image module, texture patterns, display code-buffer, texture mixer and outline shape index generator to texture-maps the predefined image module in the mixing area with the texture patterns. For some existing OSD devices, the texture-mapping method also can provide a low cost approach to fancy the original OSD display output in the display device. Moreover, changing the texture pattern is very easy to system manufacture, and it can make the user interface looks good and different. | 1. A user interface display apparatus, comprising: an image module unit for dealing with predefined image patterns; a texture pattern unit for providing texture patterns to mix with the said predefined image pattern to fancy the user interface display; a display code-buffer unit for arranging the pattern codes which are displayed on the user interface display window; and a mixer unit for mixing the patterns from said image module unit and texture pattern unit, and output the mixed signal. 2. A user interface display apparatus of claim 1, further comprising an outline shape index generator for providing the mixing index information to define the outline shape. 3. A user interface display apparatus of claim 1, wherein the predefined image pattern could be any combination of dot pixel. 4. A user interface display apparatus of claim 1, wherein the texture patterns can be defined by end-user. 5. A user interface display apparatus of claim 1, wherein the mixer unit using overlap to mix the patterns from said image module unit and texture pattern unit. 6. A user interface display apparatus of claim 1, wherein the mixer unit using alpha blending method, where output=(pattern from said image module unit)×alpha+(pattern from said texture pattern unit)×(1-alpha), the parameter alpha is a real number between 0 and 1. 7. A user interface display apparatus of claim 1, wherein the mixer unit using logic operation to mix the patterns from said image module unit and texture pattern unit. 8. A user interface display apparatus of claim 2, wherein the outline shape index generator further comprising sub-window define function. 9. A user interface display apparatus of claim 2, wherein the outline shape index generator further using alpha index for image pattern. 10. A user interface display apparatus of claim 2, wherein the outline shape index generator further using color key method for image pattern. 11. A user interface display apparatus, combined with an traditional on screen display and overlap the output signal, comprising: an image module unit for dealing with predefined image patterns; a texture pattern unit for providing texture patterns to mix with the said predefined image pattern to fancy the user interface display; a display code-buffer unit for arranging the pattern codes which are displayed on the user interface display window; and a mixer unit for mixing the patterns from said image module unit and texture pattern unit, and output the mixed signal. 12. A user interface display apparatus of claim 11, further comprising an outline shape index generator for providing the mixing index information to define the outline shape. | BACKGROUND OF THE INVENTION (A) Field of the Invention The present invention generally relates to a user interface display apparatus. More particular, the invention relates to a low cost user interface (UI) display apparatus, like on screen display (OSD) in TV, video player, projector, monitor, or display panel of telephone, consumer household appliances, electronic dictionary, calculator, electronic caption, clock, bulletin board, or pager. OSD means a display function which shows the message on screen for user to select or change some functions of application system. Normally it is overlap on the display window. (B) Description of the Related Art In the art, a display system with a low cost user interface (UI) display apparatus means a display system without powerful Central Processing Unit (CPU) and Operation System (OS) for display function, and just display the message for user to select or change which built-in function in device will be used, like used OSD in TV, computer monitor, video player, or display panel of telephone, consumer household appliances, electronic dictionary, calculator, or simply display the message for user to watch, like used in a electronic caption, clock, watch, bulletin board, and pager. The UI display in these systems is not the major function, but just provides an interface for user to adjust some functions of the system. The CPU in these systems is just fit for the major function, and no extra power for fancy display. So the UI display is usually as simple as possible and the cost of UI display apparatus is lower than the major display function device. Nowadays, the color display device like LCD will be widely used to replace many kinds of display device, but the UI display function is still simple. Compared to the powerful display ability of computer with GUI (graphic user interface) like Microsoft Windows, the UI of low cost display devices are still with a very simple form. For example, the OSD function on PC's monitor is simple, and with limited color compared to the PC versatile window operation system. That's due to the OSD function is performed in the monitor side but not in the PC side. Two methods were provided to perform the OSD function for UI display in the prior art. FIG. 1 shows UI display using a character base method. This method divides the UI display range to pieces of characters, each character 102 is predefined. A display code-buffer is used to arrange the character for display and store the character index of character set 103 for display window. For example, if a UI display window with size 128×60 dots, and each character 102 is 16×12 dots, thus the UI display window can be divided into 8×5 characters, and the size of display code-buffer 100 is 8×5×CW (“CW” is the code index width). Dmn 101 means at the matrix location (m,n) where is the display code-buffer 100 store the code for addressing the content in character set 102. A character set 103 with 256 character counts will have 8 bits CW (28=256). By the way, each character 102 color depth (D) also could be defined, typically, as 1 bit, 2 bits, 3 bits, or 4 bits. 1 bit means 2 colors, 2 bits means 4 colors and so on. In this case, the required space of a memory to store a character 102 is 16×12×D. The memory cost will depend on quantity of character font, character size, and color depth D. For some display patterns need the same text, like character “A”, we can use the same character font by setting the code-buffer index to reduce the memory usage. That's the main advantage of character base UI. FIG. 2 shows the UI using bitmap method. Bitmap method is a simple way to display all kinds of needed patterns. By predefined all kinds of patterns stored in memory bank 201, the display choose which pattern is need for current UI display 202. The pattern 200 is the one of the image stored in the memory bank 201 and will be displayed next time on UI display 202. The memory usage is huge since all patterns during user operation must be prepared and hard to be reuse. It does not take the advantage of character base method, so one pattern may need the size equal to one UI display range. The memory storage requirement is typically P times the display window sizes. P is the pattern counts of UI function, and the display window sizes depends on H×V×D, H is the horizontal size, V is the vertical size, and D is the color depth per dot. Above two methods still limited to the memory cost, and make the fancy UI hard to implement. The present invention can make the UI display much fancy with a little texture memory added. It is the simplest way for UI designer to design a fancy UI display, and make it easy to accept by end-user. Using texture mapping method can be very easy to fancy character base UI display by only adding a little texture memory. The total memory required for one character set is 16×12×D×(number of character font), where the character size is set as 16×12 dots and D colors. SUMMARY OF THE INVENTION The primary objective of the present invention is to provide a user interface display apparatus to perform on screen display function, which is using the texture mapping method. The secondary objective of the present invention is to provide a user interface display apparatus, which can provide colorful display image and user definable image. The third object of the present invention is to provide a low cost user interface display apparatus. In order to achieve the above-mentioned objectives and avoid the problems of the prior art, the present invention provides a user interface display apparatus, refer to FIG. 3, which comprises an image module 301, texture pattern 302, display code-buffer 303, and texture mixer 304. An image module 301 is dealing with the predefined image pattern, the predefined image pattern could be bitmap image, font image or small as 1 dot pixel. The dimension of image pattern can be different. It is the basic display element for UI display window, and can be character, icon, object or sub-window. The image module 301 accepts the code index from the display code-buffer 303, and uses the index to generate the image module content, then the module pixel is sent to the texture mixer 304. A texture pattern 302 is a predefined image to fill the mixed area. It accepts the texture index from the display code-buffer 300 and generates the content of texture. Then the texture pixel is sent to texture mixer 304 for mixing. A display code-buffer 303 is used to arrange the image module 301 pasted on the UI display window. It generates the code index for module 301, texture index for texture 302 patterns. A texture mixer 304 is used for mixing the pixel from image module 301 and texture pattern 302. The user interface display apparatus of the present invention further comprises an outline shape index generator 305, it generates the mixing area information for texture mixer 304. The mixing area information defines the outline shape of display from image module 301 and can be defined by several different ways, like alpha index of modules, color key method, sub-window define method, and pixel index of texture pattern. Compared with the prior art, the present invention uses the texture mapping method to provide fancy effects of on screen display and only increase a limited cost. Consequently, the present invention is a low cost and easy way for system maker to design a fancy, colorful and user-friendly interface for end-user to operate the system. It is easy to change the content of user interface display by change some texture patterns and even the user can download their favor image or photo to replace the texture patterns made by system makers. Also, the present invention can coexist with the existing OSD devices, with texture-mapping method, even the most monotonous OSD form can change to a fancy, colorful and user-friendly one. BRIEF DESCRIPTION OF THE DRAWINGS Other objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which: FIG. 1 is an example diagram showing the character base method according to the prior art; FIG. 2 is an example diagram showing the bitmap method according to the prior art; FIG. 3 is a functional block diagram of a user interface display apparatus according to the present invention; FIG. 4 is an example showing the alpha index method to define the mixed area according to the present invention; FIG. 5 is an example showing the color key method to define the mixed area according to the present invention; FIG. 6 is an example showing the sub-window method to define the mixed area according to the present invention; FIG. 7 is an example showing the texture mapping method to define the mixed display image according to the present invention; FIG. 8 is an example of user interface display using one texture pattern according to the texture mapping method of the present invention; FIG. 9 is an example of user interface display using several texture patterns according to the texture mapping method of the present invention; FIG. 10a, 10b each shows a signal flow block diagram of a user interface display apparatus according to the present invention; FIG. 11 is a function diagram of a display device embedded a user interface display apparatus. FIG. 12 is a function diagram showing how to enhance a UI display in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION Refer to FIG. 3, where shows the function diagram of a user interface (UI) using texture mapping method according to this present invention. It comprises a image module 301, a texture pattern 302, a display code-buffer 303, a texture mixer 304 and a outline shape index generator 305. An image module 301 is dealing with a predefined image pattern with size N×M×D, (N, M are the dimension in horizontal and vertical, D is the color depth) it can be large as the UI display range like bitmap method or small as 1 dot. The image module 301 provides the basic display element for UI display window. It may be a character, icon, object or sub-window. The content is pre-defined, and controlled by system maker but not affected by another system. The image module 301 accepts the code index from the display code-buffer 303, and uses the index to generate a image content, then the image pixel is sent to the texture mixer 304, and it also can provide an additional outline shape information generated by alpha index or color index to the outline shape generator 305. The texture pattern 302 provides a predefined image to fill the mixed area. It accepts the texture index from the display code-buffer 300 and generates the content of texture. Then the texture pixel is sent to texture mixer 304 for mixing. The size and the color depth of predefined texture images are no limitation. It can be the image stored in memory, or generated by pattern generator for some regular patterns like gray bar, color bar, cross talk, gradual color . . . etc. Display code-buffer 303 is used to arrange the image pasted on the UI display window. It generates the code index for image module 301, texture index for texture pattern 302, and additional information for outline shape generator 305. The sizes of display code buffer 303 will be decided by how many images in image module 301 to differentiate, and how many image patterns can be showed within a UI display window at one time. For example, if we have 256 different kinds of image patterns in image module 301, we need 8-bit codes to differentiate (CW=8), and if the UI window can accept 128 image patterns from image module 301 at one time, we need 128 locations to store the image module contents. That is the display code-buffer 303 will be 128×8 bits for overall UI display window. Moreover, additional attributes (like alpha index, color key, module scaling, flick information . . . ) may be added by module, by line or by window, so some additional bits are need for these attributes in display code-buffer 303. A texture mixer 304 is used for mixing images from image module 301 and texture pattern 302. The mixing area is defined by the outline shape index generator 305, and the methods will be explained later. The function of texture mixer 304 can be presented as follows: Output (after mixer)=f(i,j,k) Where i: module pixel; j: outline shape index generator; k: texture pixel. The mixing method can be overlap, alpha blending or logic operation. The overlap method is a way just to replace the image of module in mix area by image of texture patterns. The alpha blending method is using a parameter α with Output=Image of module×(α)+Image of texture pattern×(1−α) Where the parameter α is a real number between 0 and 1. The logic operation method is using digital logical operation like AND, OR, XOR, XNOR . . . etc. Output=(Image of module) logic operate with (Image of texture pattern). Outline shape index generator 305 generates the mixing area information for texture mixer 304. The mixing area information defines the outline shape of module 301 and can be defined by alpha index of modules, the color key method, the sub-window define method, and the pixel index of texture patterns. FIG. 4 is an example shows the method using alpha index of modules of the present invention. Alpha index means the defined index mixed with texture pattern, and the others are the color index for color information. The content of module 400 is divided into color index, alpha index 0 and alpha index 1. Alpha Index 0 means the area mixed with texture pattern 0, alpha Index 1 means the area mixed with texture pattern 1, while the color index means the area filled with the original module. The mixed weighting a between module in alpha index area and the texture pattern, and even what kinds of texture patterns are selected by texture mixer 401. The alpha index can be defined by module, by line or by area that depends on the cost. Note that, alpha index can be defined multiple in a module 400. For example, if 0xF, 0x8 both denote the alpha index, 2 kinds of texture patterns can mix in code area of 0xF and 0x8. FIG. 5 is an example shows the color key method of present invention. Since the color depth is typically not enough to get true color which is 8 bits for R, G, B channel, color look up table (palette) 501 may be needed for target display device. Module 500 in different area can be mapped to different palette or color keys. If the index in module mapped to color keys, it will be mixed with the texture pattern. For example, the content of module 500 is divided to color index 0, color index 1 and color index 2. After the color lookup table 501, color Index 0 gets color key 0, color index 1 gets color key 1, and color index 2 gets color 2. The area of color key 0 will mix with texture pattern 0, color key 1 will mix with texture pattern 1, while the color 2 means the area will fill with color 2 of palette. The mixed weighting α between module in color keys area and the texture pattern, and what kinds of texture patterns are selected for texture mixer 502, and even the alpha index can be defined by module, by line or by area depend on the cost. The color key is similar to alpha index in practice, since the alpha index may be the same as the color key before the palette 501. But there is some difference. For alpha index with 4 bits color depth, the sum of the color index for module and alpha index is only 16, but for color key method, the palette can be much larger (ex: 256) and the index of module can be mapped to the whole palette. Therefore, the restriction of alpha index is not exited in color key method. So color key can be used to extend the flexibility of alpha index for UI designer. FIG. 6 is an example shows the sub-window defined method of present invention. The UI display window 600 is divided by the parts of “without mixing area”, and “mixing area defined by sub-window”. We can define a sub-window within the UI display window, and any pixel within the area will mix with the texture pattern. Rectangle shape is easy to define by sub-window, but an irregular shape is difficult. FIG. 7 is an example shows the texture patterns index defined method of present invention. The texture pattern is divided into “without mixing area” 702, and “mixing area” 701. The mixed weighting α between module 703 and the texture pattern 700 is defined for texture mixer. Using the method, an irregular shape is very easy to define and attach as display result 704. FIG. 8 is an example shows the result of using the texture pattern 803 to texture-map the UI display. The texture pattern 803 is used repeatedly within the whole UI display window 800. The other images on the UI display window 800 are the image modules, or objects composed by modules. FIG. 9 is an example shows the result of using the texture pattern 903, 904, 905, 906, and 907 to texture-map the UI display. The other images on the UI display window 900 are the images from image module, or objects composed by image modules. With the different texture pattern, the UI display 900 in FIG. 9 is different with UI display 800 in FIG. 8. Thus it is easy to change the UI display looking by just change some texture patterns. This feature is also important for end-user who likes to change the UI display looking by himself. The system maker can support the download capacity in system, and then the end-users can download their own image to the texture patterns instead of that made by system makers. FIG. 10a shows the flow diagram of the implementation of a UI display system using texture-mapping method according to the present invention. The display code-buffer 1000 stored the module index, and arranges the location of module, content of UI to display. The sets of modules 1001 are the memory banks of modules, which stored the module content. The content may be font, icon or image. The color lookup table 1002 is a color transfer block for target display. It's generally named palette in many applications and it can be performed by another way as show in FIG. 10b. It accepts the input index, and transfers the index to a pre-defined color. The sets of texture patterns 1003 are the pre-defined patterns, like image, or regular patterns generated by some pattern generator like gray bar, gradual color, color bar . . . etc. The mixer 1004 is used for mixing the module content and texture content. The mixing information is alpha index from sets of modules 1000, color index from color lookup table 1001, the sub-window information from the sub-window definition, or index from texture patterns. Other inputs are the weighting of mixing, function of mixing, or some attributes defined by the UI designer. The UI display pixel 1005 is the final result and shown in UI display window for end-user. FIG. 11 is a function diagram shows a typical display device. The UI display apparatus 1101 is a sub-system of a display device 1103. The major function 1104 of display device accepts input signal 1103, the input signal comes from VCR, TV, PC, or computer signal, said input signal enter into the major function 1104 and processing therein, like scaling, filtering of DSP processor. With an overlap mixer 1101, the processed signal is mixed with the UI signal, then output the mixed result to the display. The said display device 1102 is a system like TV, video player, projector, or monitor applications with an OSD sub-system. FIG. 12 is a method using the present invention to fancy UI display for existing device. Some display device integrate the OSD, they can be re-designed easily to use texture-mapping method. But some display device uses an external stand-alone OSD 1201 (or caption) product due to pin counts limitation, these kinds of OSD have limited and monotone colors (typically, with each R, G, B 1 bit or 2 bits). The external stand-alone OSD 1201 uses character base method to generate OSD data. But in display device, we can use the texture-mapping block 1207, with the alpha index from external OSD 1201, color key from color lookup table 1202, sub-window method, or texture pattern index to define the mixed area for incoming external OSD. For example, we can use RGB=111 as the alpha index for mixing. The texture mixer 1203 gets alpha index from external stand-alone OSD 1201, color or color key from color lookup table 1202, texture pixel from texture patterns 1206, plus sub-window information and the weighting of mixing, function of mixing, or some attributes defined by the UI designer, then the UI display pixel 1204 is generated, and texture mapped. The UI result then mixed by overlap mixer 1205 with the major display pixels from the processed of input signal likes TV, video, computer, and send to display. This invention is a low cost solution and can be implemented in the UI applications of TV, video Player, projector, and monitor, or display panel of telephone, consumer household appliances, electronic dictionary, calculator . . . ) or to display the message for user to watch (electronic caption, clock, watch, bulletin board, pager . . . ) with a colorful and fancy user interface. The present invention a UI display system using texture-mapping method is a low cost and easy way for system maker to design a fancy, colorful and user-friendly interface for end-user to operate the system. It is easy to change the content of UI display by changing texture patterns and even the end-user can download their favor image or photo to replace the texture patterns made by system makers if system supports it. Also, the present invention can coexist with the existing OSD devices. With texture-mapping method, even the most monotonous OSD can be changed to a fancy, colorful and user-friendly one. The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>(A) Field of the Invention The present invention generally relates to a user interface display apparatus. More particular, the invention relates to a low cost user interface (UI) display apparatus, like on screen display (OSD) in TV, video player, projector, monitor, or display panel of telephone, consumer household appliances, electronic dictionary, calculator, electronic caption, clock, bulletin board, or pager. OSD means a display function which shows the message on screen for user to select or change some functions of application system. Normally it is overlap on the display window. (B) Description of the Related Art In the art, a display system with a low cost user interface (UI) display apparatus means a display system without powerful Central Processing Unit (CPU) and Operation System (OS) for display function, and just display the message for user to select or change which built-in function in device will be used, like used OSD in TV, computer monitor, video player, or display panel of telephone, consumer household appliances, electronic dictionary, calculator, or simply display the message for user to watch, like used in a electronic caption, clock, watch, bulletin board, and pager. The UI display in these systems is not the major function, but just provides an interface for user to adjust some functions of the system. The CPU in these systems is just fit for the major function, and no extra power for fancy display. So the UI display is usually as simple as possible and the cost of UI display apparatus is lower than the major display function device. Nowadays, the color display device like LCD will be widely used to replace many kinds of display device, but the UI display function is still simple. Compared to the powerful display ability of computer with GUI (graphic user interface) like Microsoft Windows, the UI of low cost display devices are still with a very simple form. For example, the OSD function on PC's monitor is simple, and with limited color compared to the PC versatile window operation system. That's due to the OSD function is performed in the monitor side but not in the PC side. Two methods were provided to perform the OSD function for UI display in the prior art. FIG. 1 shows UI display using a character base method. This method divides the UI display range to pieces of characters, each character 102 is predefined. A display code-buffer is used to arrange the character for display and store the character index of character set 103 for display window. For example, if a UI display window with size 128×60 dots, and each character 102 is 16×12 dots, thus the UI display window can be divided into 8×5 characters, and the size of display code-buffer 100 is 8×5×CW (“CW” is the code index width). Dmn 101 means at the matrix location (m,n) where is the display code-buffer 100 store the code for addressing the content in character set 102 . A character set 103 with 256 character counts will have 8 bits CW (2 8 =256). By the way, each character 102 color depth (D) also could be defined, typically, as 1 bit, 2 bits, 3 bits, or 4 bits. 1 bit means 2 colors, 2 bits means 4 colors and so on. In this case, the required space of a memory to store a character 102 is 16×12×D. The memory cost will depend on quantity of character font, character size, and color depth D. For some display patterns need the same text, like character “A”, we can use the same character font by setting the code-buffer index to reduce the memory usage. That's the main advantage of character base UI. FIG. 2 shows the UI using bitmap method. Bitmap method is a simple way to display all kinds of needed patterns. By predefined all kinds of patterns stored in memory bank 201 , the display choose which pattern is need for current UI display 202 . The pattern 200 is the one of the image stored in the memory bank 201 and will be displayed next time on UI display 202 . The memory usage is huge since all patterns during user operation must be prepared and hard to be reuse. It does not take the advantage of character base method, so one pattern may need the size equal to one UI display range. The memory storage requirement is typically P times the display window sizes. P is the pattern counts of UI function, and the display window sizes depends on H×V×D, H is the horizontal size, V is the vertical size, and D is the color depth per dot. Above two methods still limited to the memory cost, and make the fancy UI hard to implement. The present invention can make the UI display much fancy with a little texture memory added. It is the simplest way for UI designer to design a fancy UI display, and make it easy to accept by end-user. Using texture mapping method can be very easy to fancy character base UI display by only adding a little texture memory. The total memory required for one character set is 16×12×D×(number of character font), where the character size is set as 16×12 dots and D colors. | <SOH> SUMMARY OF THE INVENTION <EOH>The primary objective of the present invention is to provide a user interface display apparatus to perform on screen display function, which is using the texture mapping method. The secondary objective of the present invention is to provide a user interface display apparatus, which can provide colorful display image and user definable image. The third object of the present invention is to provide a low cost user interface display apparatus. In order to achieve the above-mentioned objectives and avoid the problems of the prior art, the present invention provides a user interface display apparatus, refer to FIG. 3 , which comprises an image module 301 , texture pattern 302 , display code-buffer 303 , and texture mixer 304 . An image module 301 is dealing with the predefined image pattern, the predefined image pattern could be bitmap image, font image or small as 1 dot pixel. The dimension of image pattern can be different. It is the basic display element for UI display window, and can be character, icon, object or sub-window. The image module 301 accepts the code index from the display code-buffer 303 , and uses the index to generate the image module content, then the module pixel is sent to the texture mixer 304 . A texture pattern 302 is a predefined image to fill the mixed area. It accepts the texture index from the display code-buffer 300 and generates the content of texture. Then the texture pixel is sent to texture mixer 304 for mixing. A display code-buffer 303 is used to arrange the image module 301 pasted on the UI display window. It generates the code index for module 301 , texture index for texture 302 patterns. A texture mixer 304 is used for mixing the pixel from image module 301 and texture pattern 302 . The user interface display apparatus of the present invention further comprises an outline shape index generator 305 , it generates the mixing area information for texture mixer 304 . The mixing area information defines the outline shape of display from image module 301 and can be defined by several different ways, like alpha index of modules, color key method, sub-window define method, and pixel index of texture pattern. Compared with the prior art, the present invention uses the texture mapping method to provide fancy effects of on screen display and only increase a limited cost. Consequently, the present invention is a low cost and easy way for system maker to design a fancy, colorful and user-friendly interface for end-user to operate the system. It is easy to change the content of user interface display by change some texture patterns and even the user can download their favor image or photo to replace the texture patterns made by system makers. Also, the present invention can coexist with the existing OSD devices, with texture-mapping method, even the most monotonous OSD form can change to a fancy, colorful and user-friendly one. | 20040330 | 20060502 | 20051006 | 67133.0 | 1 | RAHMJOO, MANUCHEHR | USER INTERFACE DISPLAY APPARATUS USING TEXTURE MAPPING METHOD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,310 | ACCEPTED | Asynchronous FIFO apparatus and method for passing data between a first clock domain and a second clock domain of a data processing apparatus | The present invention provides an asynchronous FIFO apparatus and method for passing data between a first clock domain and a second clock domain of a data processing apparatus, the first clock domain being asynchronous with respect to the second clock domain. The asynchronous FIFO apparatus comprises a main FIFO memory operable to store the data to be passed between the first and second clock domains, the main FIFO memory being accessible from each clock domain under the control of an access pointer associated with that clock domain. For one or both of the clock domains, the amount of data accessible per clock cycle is variable. An auxiliary FIFO memory is also provided associated with each clock domain in which the amount of data accessible per clock cycle is variable, this auxiliary FIFO memory being operable to store the access pointer used to access the main FIFO memory from its associated clock domain, and the access pointer being stored at a location of the auxiliary FIFO memory specified by an auxiliary access pointer. Routing logic is then operable to pass the auxiliary access pointer to the other clock domain to enable that other clock domain to retrieve the access pointer stored in the auxiliary FIFO memory. This provides an efficient technique for enabling data to be passed between two asynchronous clock domains in situations where for at least one of the clock domains the amount of data accessible per clock cycle in the main FIFO memory is variable. | 1. An asynchronous FIFO apparatus for a data processing apparatus having a first clock domain and a second clock domain, the first clock domain being asynchronous with respect to the second clock domain, the asynchronous FIFO apparatus being operable to pass data between the first clock domain and the second clock domain and comprising: a main FIFO memory operable to store said data to be passed between the first clock domain and the second clock domain, the main FIFO memory being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; an auxiliary FIFO memory associated with said one of said first and second clock domains and operable to store the access pointer used to access the main FIFO memory from that clock domain, the access pointer being stored at a location of the auxiliary FIFO memory specified by an auxiliary access pointer; and routing logic operable to pass the auxiliary access pointer to the other of said first and second clock domains to enable that other of the first and second clock domains to retrieve the access pointer stored in the auxiliary FIFO memory. 2. An asynchronous FIFO apparatus as claimed in claim 1, wherein the routing logic performs a coding on the auxiliary access pointer in order to generate a coded auxiliary access pointer for passing to the other of said first and second clock domains. 3. An asynchronous FIFO apparatus as claimed in claim 2, wherein the routing logic performs a gray coding operation on the auxiliary access pointer in order to generate a gray coded auxiliary access pointer. 4. An asynchronous FIFO apparatus as claimed in claim 1, wherein the main FIFO memory is accessible from the first clock domain under the control of a write access pointer in order to write data into the main FIFO memory, and the main FIFO memory is accessible from the second clock domain under the control of a read access pointer in order to read data from the main FIFO memory. 5. An asynchronous FIFO apparatus as claimed in claim 4, wherein: for said first clock domain the amount of data writeable into the main FIFO memory per clock cycle is variable; the auxiliary FIFO memory is a write pointer FIFO memory operable to store the write access pointer used to access the main FIFO memory from the first clock domain; and the routing logic is operable to pass the auxiliary access pointer to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO memory; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO memory to be read. 6. An asynchronous FIFO apparatus as claimed in claim 4, wherein: for said second clock domain the amount of data readable from the main FIFO memory per clock cycle is variable; the auxiliary FIFO memory is a read pointer FIFO memory operable to store the read access pointer used to access the main FIFO memory from the second clock domain; and the routing logic is operable to pass the auxiliary access pointer to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO memory; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO memory is full. 7. An asynchronous FIFO apparatus as claimed in claim 4, wherein: for both of said first and second clock domains the amount of data accessible per clock cycle is variable, the auxiliary FIFO memory comprising first and second auxiliary FIFO memories, each with associated routing logic; the first auxiliary FIFO memory being a write pointer FIFO memory operable to store the write access pointer used to access the main FIFO memory from the first clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the write pointer FIFO memory to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO memory; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO memory to be read; the second auxiliary FIFO memory being a read pointer FIFO memory operable to store the read access pointer used to access the main FIFO memory from the second clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the read pointer FIFO memory to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO memory; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO memory is full. 8. A data processing apparatus comprising: a first element operating in a first clock domain; a second element operating in a second clock domain; and an asynchronous FIFO apparatus as claimed in claim 1, operable to pass data between the first element and the second element. 9. A data processing apparatus as claimed in claim 8, further comprising: a trace module operable to produce trace data indicative of the activity of the first element, the trace module including said asynchronous FIFO apparatus; wherein the main FIFO memory is accessible from the first clock domain under the control of a write access pointer in order to write into the main FIFO memory the trace data, and the main FIFO memory is accessible from the second clock domain under the control of a read access pointer in order to read from the main FIFO memory the trace data for passing to the second element. 10. A data processing apparatus as claimed in claim 9, wherein a power supply voltage to the first element is variable, and a clock frequency of the first clock domain is operable to change in dependence on the power supply voltage. 11. A method of passing data between a first clock domain and a second clock domain of a data processing apparatus, the first clock domain being asynchronous with respect to the second clock domain, the method comprising the steps of: (a) storing within a main FIFO memory said data to be passed between the first clock domain and the second clock domain, the main FIFO memory being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; (b) storing within an auxiliary FIFO memory associated with said one of said first and second clock domains the access pointer used to access the main FIFO memory from that clock domain, the access pointer being stored at a location of the auxiliary FIFO memory specified by an auxiliary access pointer; (c) passing the auxiliary access pointer to the other of said first and second clock domains; and (d) retrieving, at the other of the first and second clock domains, the access pointer stored in the auxiliary FIFO memory. 12. A method as claimed in claim 11, further comprising the step, prior to said step (c) of performing a coding on the auxiliary access pointer in order to generate a coded auxiliary access pointer for passing at said step (c) to the other of said first and second clock domains. 13. A method as claimed in claim 12, wherein said step of performing a coding comprises the step of performing a gray coding operation on the auxiliary access pointer in order to generate a gray coded auxiliary access pointer. 14. A method as claimed in claim 11, wherein the main FIFO memory is accessible from the first clock domain under the control of a write access pointer in order to write data into the main FIFO memory, and the main FIFO memory is accessible from the second clock domain under the control of a read access pointer in order to read data from the main FIFO memory. 15. A method as claimed in claim 14, wherein: for said first clock domain the amount of data writeable into the main FIFO memory per clock cycle is variable; the auxiliary FIFO memory is a write pointer FIFO memory operable to store at said step (b) the write access pointer used to access the main FIFO memory from the first clock domain; said step (c) comprises the step of passing the auxiliary access pointer to the second clock domain; said step (d) comprises the step of retrieving, at the second clock domain, the write access pointer stored in the write pointer FIFO memory; and the method further comprises the step, in the second clock domain, of reading from the main FIFO memory, in response to the write access pointer, the associated data stored in the main FIFO memory. 16. A method as claimed in claim 14, wherein: for said second clock domain the amount of data readable from the main FIFO memory per clock cycle is variable; the auxiliary FIFO memory is a read pointer FIFO memory operable to store at said step (b) the read access pointer used to access the main FIFO memory from the second clock domain; said step (c) comprises the step of passing the auxiliary access pointer to the first clock domain; said step (d) comprises the step of retrieving, at the first clock domain, the read access pointer stored in the read pointer FIFO memory; and the method further comprises the step, in the first clock domain, of determining, in response to the read access pointer, whether the main FIFO memory is full. 17. A method as claimed in claim 14, wherein: for both of said first and second clock domains the amount of data accessible per clock cycle is variable, the auxiliary FIFO memory comprising first and second auxiliary FIFO memories, and said steps (b), (c) and (d) being performed for each auxiliary FIFO memory; the first auxiliary FIFO memory being a write pointer FIFO memory operable to store at said step (b) the write access pointer used to access the main FIFO memory from the first clock domain, said associated step (c) comprising the step of passing the auxiliary access pointer to the second clock domain, and said associated step (d) comprising the step of retrieving, at the second clock domain, the write access pointer stored in the write pointer FIFO memory; and the method further comprising the step, in the second clock domain, of reading from the main FIFO memory, in response to the write access pointer, the associated data stored in the main FIFO memory; the second auxiliary FIFO memory being a read pointer FIFO memory operable to store at said step (b) the read access pointer used to access the main FIFO memory from the second clock domain, said associated step (c) comprising the step of passing the auxiliary access pointer to the first clock domain, said associated step (d) comprising the step of retrieving, at the first clock domain, the read access pointer stored in the read pointer FIFO memory; and the method further comprising the step, in the first clock domain, of determining, in response to the read access pointer, whether the main FIFO memory is full. 18. A method of operating a data processing apparatus, comprising the steps of: providing a first element operating in a first clock domain; providing a second element operating in a second clock domain; and performing a method as claimed in claim 11 to pass data between the first element and the second element. 19. A method as claimed in claim 18, further comprising the step of: employing a trace module to produce trace data indicative of the activity of the first element, the method being performed within the trace module; wherein the main FIFO memory is accessible from the first clock domain under the control of a write access pointer in order to write into the main FIFO memory the trace data, and the main FIFO memory is accessible from the second clock domain under the control of a read access pointer in order to read from the main FIFO memory the trace data for passing to the second element. 20. A method as claimed in claim 19, further comprising the step of varying a power supply voltage to the first element, a clock frequency of the first clock domain changing in dependence on the power supply voltage. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to asynchronous FIFO (First-In-First-Out) memories, and in particular to an improved asynchronous FIFO apparatus and method for passing data between a first clock domain and a second clock domain of a data processing apparatus. 2. Description of the Prior Art It is known to use an asynchronous FIFO memory to pass data between first and second clock domains in a data processing apparatus, for example a microchip design/implementation, such an approach typically being used if the first clock domain is asynchronous with respect to the second clock domain (i.e. the clock frequency in the first clock domain is asynchronous with respect to the clock frequency in the second clock domain). However, current designs of asynchronous FIFO memories only operate correctly if there are a constant number of input bits of data into the FIFO memory (herein the term “FEFO” will sometimes be used as an abbreviation for “FIFO memory”) in each clock cycle in which it is desired to write data to the FIFO. Similarly, on the output side of the FIFO, current designs of asynchronous FIFOs only work if there is a constant number of output bits of data from the FIFO in each clock cycle in which it is desired to read data from the FIFO. This restriction is required due to the asynchronous nature of the two clock domains, and the need to ensure that any pointer value passed between the two clock domains will be correctly read in the target domain. In particular, considering the example of the write side of the FIFO, if a constant number of input bits (say for example one byte) is written into the FIFO during a particular clock circle, then this enables the write pointer to the incremented by a predetermined amount (in this example one). A gray coding process can then be applied to the write pointer before it is passed into the read domain, and because the write pointer is always incremented by the same predetermined amount, this will ensure that the gray coded write pointer only differs from its previous value by one bit. This ensures that when that gray coded write pointer is sampled in the read domain, it is only possible for the read domain to either get the correct current value, or the previous value, of the write pointer, thus avoiding any mis-reading of the write pointer. Accordingly, it is then possible in the read domain to correctly read the associated data from the FIFO. It is important to note that the above gray coding process only works correctly when a constant number of bits of data are written into the FIFO in each cycle in which it is desired to write data, since otherwise more than one bit of the gray coded write pointer could be different from the previous gray coded write pointer, which will compromise the integrity of the value read in the read domain. For example, in the above instance, given the asynchronous nature of the read clock domain to the write clock domain, it may be the case that when the read clock domain samples the gray coded write pointer, only one of the bits will have changed, which the read domain would then interpret as a valid gray coded write pointer, even though it is in fact incorrect. Due to recent developments in data processing designs, it is becoming more commonplace for different asynchronous clock domains to exist within a data processing apparatus. As an example, there has recently been much development in the area of Intelligent Energy Management (IEM), where the voltage supply to particular components of a data processing apparatus may be reduced during periods of inactivity in order to save energy consumption within the data processing apparatus. The implementation of such IEM techniques can give rise to the presence of multiple asynchronous clock domains within the design of a particular data processing apparatus. Whilst current asynchronous FIFO designs can be used to pass data between these differing clock domains in situations where the above constraints on input bits of data and output bits of data are observed, there are a number of instances where certain elements of the data processing apparatus will produce data in a non-constant, or bursty, manner, and current asynchronous FIFO designs will not enable such data to be passed between two asynchronous clock domains, due to the earlier described restrictions required by such asynchronous FIFO designs. Accordingly, it is an object of the present invention to provide an improved asynchronous FIFO design which alleviates the above-mentioned problems. SUMMARY OF THE INVENTION Viewed from a first aspect, the present invention provides an asynchronous FIFO apparatus for a data processing apparatus having a first clock domain and a second clock domain, the first clock domain being asynchronous with respect to the second clock domain, the asynchronous FIFO apparatus being operable to pass data between the first clock domain and the second clock domain and comprising: a main FIFO operable to store said data to be passed between the first clock domain and the second clock domain, the main FIFO being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; an auxiliary FIFO associated with said one of said first and second clock domains and operable to store the access pointer used to access the main FIFO from that clock domain, the access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer; and routing logic operable to pass the auxiliary access pointer to the other of said first and second clock domains to enable that other of the first and second clock domains to retrieve the access pointer stored in the auxiliary FIFO. In accordance with the present invention, an asynchronous FIFO apparatus is provided which includes a main FIFO for storing data to be passed between a first clock domain and a second clock domain, and an auxiliary FIFO associated with one of the domains in which the amount of data accessible per clock cycle in the main FIFO is variable. In particular, for that clock domain, the auxiliary FIFO is used to store the access pointer used to access the main FIFO, this access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer. Then, in accordance with the present invention, routing logic is used to pass the auxiliary access pointer to the other clock domain to enable that other clock domain to retrieve the access pointer stored in the auxiliary FIFO. Since the amount of data accessible per clock cycle in the main FIFO is variable, this means that the associated changes in the access pointer for the main FIFO are also variable. However, the present invention takes advantage of the fact that even if the changes to the access pointer are variable, the access pointer itself will always be specified by a constant number of bits, and accordingly if the access pointer is stored in the auxiliary FIFO, then the auxiliary access pointer can always be incremented by a constant amount. Accordingly, this enables the auxiliary access pointer to be passed between the two clock domains in a manner which allows it to be accurately sampled in the recipient clock domain. It will be appreciated that, depending on the number of locations within the auxiliary FIFO, and the way in which the auxiliary access pointers are arranged, it may be possible to constrain the auxiliary access pointers so that any incremented auxiliary access pointer only differs from its previous value by one bit, in which event the auxiliary access pointer can be directly passed by the routing logic to the other clock domain. However, in one embodiment, the routing logic performs a coding on the auxiliary access pointer in order to generate a coded auxiliary access pointer for passing to the other of said first and second clock domains. The coding is chosen in such a way as to ensure that any new coded auxiliary access pointer only differs from a preceding coded auxiliary access pointer by one bit, thus ensuring integrity in the reading of the coded auxiliary access pointer by the recipient clock domain. In one particular embodiment, the routing logic performs a gray coding operation on the auxiliary access pointer in order to generate a gray coded auxiliary access pointer. It has been found that gray coding is a particularly efficient technique for coding the auxiliary access pointer so that when that pointer is sampled in the recipient clock domain, it is only possible for it to be either the current value or the previous value of the gray coded auxiliary access pointer. It will be appreciated that the manner in which the asynchronous FIFO apparatus interfaces between the first clock domain and the second clock domain can take a variety of forms. However, in one embodiment, the main FIFO is accessible from the first clock domain under the control of a write access pointer in order to write data into the main FIFO, and the main FIFO is accessible from the second clock domain under the control of a read access pointer in order to read data from the main FIFO. Hence, in this embodiment, data is written into the FIFO from elements of the data processing apparatus provided in the first clock domain, and then data is read from the FIFO by elements of the data processing apparatus provided in the second clock domain. It will be appreciated that the clock domain in which the amount of data accessible per clock cycle in the main FIFO is variable can be either the first clock domain, the second clock domain, or indeed both clock domains. In one embodiment, for said first clock domain the amount of data writeable into the main FIFO per clock cycle is variable; the auxiliary FIFO is a write pointer FIFO operable to store the write access pointer used to access the main FIFO from the first clock domain; and the routing logic is operable to pass the auxiliary access pointer to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO to be read. Hence, in accordance with this embodiment, write pointers are stored in the auxiliary FIFO, and routing of the auxiliary access pointer to the second clock domain enables the write access pointer to be retrieved, and for read logic in the second clock domain to then cause the associated data stored in the main FIFO to be read. In an alternative embodiment, for said second clock domain the amount of data readable from the main FIFO per clock cycle is variable; the auxiliary FIFO is a read pointer FIFO operable to store the read access pointer used to access the main FIFO from the second clock domain; and the routing logic is operable to pass the auxiliary access pointer to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO is full. In accordance with this embodiment, a read access pointer is stored within the auxiliary FIFO, and routing of the auxiliary access pointer to the first clock domain enables the read access pointer to be retrieved, and for write control logic in the first clock domain to then determine, in response to the read access pointer, whether the main FIFO is full. Typically, if the main FIFO is full, the write control logic will prevent any new data being written into the main FIFO until space is available, in order to avoid any data being overwritten in the main FIFO that has not yet been read in the second clock domain. In an alternative embodiment, for both of said first and second clock domains the amount of data accessible per clock cycle is variable, the auxiliary FIFO comprising first and second auxiliary FIFOs, each with associated routing logic; the first auxiliary FIFO being a write pointer FIFO operable to store the write access pointer used to access the main FIFO from the first clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the write pointer FIFO to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO to be read; the second auxiliary FIFO being a read pointer FIFO operable to store the read access pointer used to access the main FIFO from the second clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the read pointer FIFO to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO is full. In accordance with this embodiment, both a write pointer FIFO and a read pointer FIFO are provided, each having associated routing logic, this hence enabling write pointers to be reliably passed between the first and second clock domains via an associated auxiliary access pointer, and also for read access pointers to be reliably passed from the second clock domain to the first clock domain via associated auxiliary access pointers. In this embodiment, both the amount of data writeable to the main FIFO per clock cycle is variable, and the amount of data readable from the main FIFO per clock cycle is variable. Viewed from a second aspect, the present invention provides a data processing apparatus comprising: a first element operating in a first clock domain; a second element operating in a second clock domain; and an asynchronous FIFO apparatus in accordance with the first embodiment of the present invention, operable to pass data between the first element and the second element. In one particular embodiment, the data processing apparatus further comprises: a trace module operable to produce trace data indicative of the activity of the first element, the trace module including said asynchronous FIFO apparatus; wherein the main FIFO is accessible from the first clock domain under the control of a write access pointer in order to write into the main FIFO the trace data, and the main FIFO is accessible from the second clock domain under the control of a read access pointer in order to read from the main FIFO the trace data for passing to the second element. Hence, in accordance with: this embodiment, an asynchronous FIFO apparatus is provided within a trace module, with the data stored within the main FIFO being trace data. In one particular implementation of such an embodiment, the first element may be a processor core, and the second element may be a trace buffer used to store trace data prior to output to a trace analysis tool. In one embodiment, a power supply voltage to the first element is variable, and a clock frequency of the first clock domain is operable to change in dependence on the power supply voltage. In one particular implementation of such an embodiment, the data processing apparatus may incorporate Intelligent Energy Management (EEM) logic which enables the power supply voltage to the first element to be reduced when the first element is less busy, in order to provide energy consumption savings. This variation in the power supply voltage has a knock-on effect on the clock frequency within the first clock domain, and this in turn causes a variation in the rate of writing of trace data into the main FIFO. Viewed from a second aspect, the present invention provides a method of passing data between a first clock domain and a second clock domain of a data processing apparatus, the first clock domain being asynchronous with respect to the second clock domain, the method comprising the steps of: (a) storing within a main FIFO said data to be passed between the first clock domain and the second clock domain, the main FIFO being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; (b) storing within an auxiliary FIFO associated with said one of said first and second clock domains the access pointer used to access the main FIFO from that clock domain, the access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer; (c) passing the auxiliary access pointer to the other of said first and second clock domains; and (d) retrieving, at the other of the first and second clock domains, the access pointer stored in the auxiliary FIFO. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described further, by way of example only, with reference to preferred embodiments thereof as illustrated in the accompanying drawings, in which: FIG. 1 is a diagram schematically illustrating an asynchronous FIFO apparatus in accordance with one embodiment of the present invention; FIG. 2 is a block diagram illustrating in more detail the asynchronous FIFO apparatus of one embodiment of the present invention; FIGS. 3A to 3D are flow diagrams illustrating the operation of the asynchronous FIFO apparatus of FIG. 2; FIG. 4 is a block diagram illustrating a data processing apparatus incorporating an on-chip trace module in which the asynchronous FIFO apparatus of one embodiment of the present invention may be employed; and FIG. 5 is a diagram illustrating in more detail the structure of the on-chip trace module of FIG. 4. DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 illustrates an asynchronous FIFO apparatus in accordance with one embodiment of the present invention. This asynchronous FIFO apparatus includes a main FIFO 200 for storing data written into the main FIFO over path 220, and from which data can subsequently be read over path 225. Data is written into the main FIFO 200 in the first clock domain (CLK1) and data is read from the main FIFO 200 in the second clock domain (CLK2), the dotted line 215 in FIG. 1 schematically illustrating the demarcation between the first and second clock domains. Data stored into the main FIFO 200 over path 220 is stored at locations within the FIFO indicated by a write pointer WPMAINFIFO. As data is written into a location specified by a particular WPMAINFIFO value, then that WPMAINFIFO value is written into the write pointer FIFO 210 at a location indicated by a write pointer for that write pointer FIFO, this write pointer being referred to hereafter as WPWPFIFO. This WPWPFIFO value is then subjected to gray coding, and passed from the first clock domain to the second clock domain, where it is then ungray coded in order to identify the location in the write pointer FIFO 210 containing the write pointer WPMAINFIFO. This WPMAINFIFO value can then be used to access the associated data value in the main FIFO 200 to enable it to be read out over path 225. Through the provision of this logic, it does not matter if the amount of data. written into the main FIFO in any particular clock cycle varies, since whilst this will cause the incrementation between WPMAINFIFO values to vary, each WPMAINFIFO value will be of the same size, and accordingly as each WPMAINFIFO value is stored into the write pointer FIFO 210, the WPWPFIFO value will be incremented by the same predetermined amount each time. Accordingly, this value can be reliably passed from the first clock domain to the second clock domain without any risk of being misread by the second clock domain due to the asynchronous nature of the first and second clock domains. Similarly, on the read side, a read pointer FIFO 205 is provided for storing read pointer values used to access particular locations within the main FIFO 200. In particular, when data is read from the main FIFO 200, the associated read pointer value, hereafter referred to as RPMAINFIFO is passed to the read pointer FIFO 205, where it is stored in the location indicated by a write pointer for the read pointer FIFO, hereafter referred to as WPRPFIFO. Again, although the amount of data read from the main FIFO 200 may vary, and accordingly the changes in the RPMAINFIFO may vary, the changes in the WPRPFIFO value will be by a constant, predetermined, value each time, and accordingly the WPRPFIFO value can reliably be passed from the second clock domain to the first clock domain. This then enables the RPMAINFIFO value stored in the read pointer FIFO 205 to be retrieved and used to determined whether the main FIFO 200 is full. This will be the case if, when the next block of data is to be written into the main FIFO 200, the size of that data, when added to the difference between the RPMAINFIFO value and the current WPMAINFIFO value, exceeds the size of the main FIFO 200. A more detailed description of the asynchronous FIFO apparatus of FIG. 1 will now be provided with reference to FIG. 2, the operation of the asynchronous FIFO apparatus of FIG. 2 being described with reference to the flow diagram of FIGS. 3A to 3D. As shown in FIG. 2, each FIFO has write pointer generation logic and read pointer generation logic associated therewith. In particular, the main FIFO 200 has associated therewith the main write pointer generation logic 330 and the main read pointer generation logic 340, the write pointer FIFO 210 has the WPWPFIFO generation logic 350 and the RPWPFIFO generation logic 360 associated therewith, and the read pointer FIFO 205 has the WPRPFIFO generation logic 400 and the RPRPFIFO generation logic 410 associated therewith. FIGS. 3A to 3D are flow diagrams showing a loop of processing performed by the logic of FIG. 2. FIG. 3A shows a sequence of processing performed within the first clock domain CLK1. The process starts at point 500, and proceeds to step 505, where it is determined by the main write pointer generation logic 330 whether there is new data to be written into the main FIFO 200 over path 220. If not, the process waits at step 505 until there is new data to be written. Then, the process proceeds to step 510, where the main write pointer generation logic 330 determines whether the main FIFO is full. As can be seen from FIG. 2, the main write pointer generation logic 330 receives an input signal from the logic element 335, which performs an unlike-signed addition operation on its two input signals, these input signals being the current value of WPMAINFIFO and the data read from the read pointer FIFO 205. As will be discussed later, this data read from the read pointer FIFO 205 actually provides a value of RPMAINFIFO, and accordingly by performing an unlike-signed addition on the WPMAINFIFO value and the RPMAINFIFO value, this provides an indication as to the number of bytes stored in the main FIFO 200 which have not yet been read. The main write pointer generation logic 330 will also receive information concerning the number of bytes of data for the current data block to be written into the main FIFO. This value is then added to the output from the unlike-signed addition logic 335, and the main write pointer generation logic 330 will conclude that the main FIFO 200 is not full as long as the computed value does not exceed the capacity of the main FIFO 200. If it is determined at step 510 that the main FIFO is full, then the process waits at step 510 until it is determined that the main FIFO is no longer full, i.e. because in the interim period sufficient data has been read out from the main FIFO 200. Once it is determined that the main FIFO is not full, the process proceeds to step 515, where the write data on path 220 is written into one or more of the registers 300 of the main FIFO starting at a register location indicated by the value of WPMAINFIFO. This value of WPMAINFIFO is generated by the main write pointer generation logic 330, and is output to the main FIFO 200 and also forwarded as write data to the write pointer FIFO 210. Then, at step 520, the WPWPFIFO generation logic 350 determines whether the write pointer FIFO 210 is full, this analysis taking place in an analogous way to that described earlier with reference to the main write pointer generation logic 330. Hence, the unlike-signed addition logic 355 receives as one input the current value of WPWPFIFO, and receives as the other input the current value of the RPWPFIFO, this value having been routed from the second clock domain to the first clock domain via the gray coding logic 385 the two metastability synchronisation registers 390, and the ungray coding logic 395. As illustrated schematically in FIG. 2, the write pointer FIFO 210 of FIG. 2 has three storage registers 310, and accordingly there are three possible values for the read pointer. In one embodiment, the gray coding logic 385 produces the following gray codings dependent on the value of the read pointer: TABLE 1 Encoding[p-1:0] Encoding[p] (Read Pointer) Gray Code[p:0] 0 000 = 0 0000 0 001 = 1 0010 0 010 = 2 0011 1 000 = 0 1101 1 001 = 1 1001 1 010 = 2 1011 As can be seen from Table 1, the read pointer may have the values 000, 001 or 010, identifying locations 0, 1 or 2 of the write pointer FIFO 210. These values get gray coded by the gray coding logic 385 to form the lower three bits of a gray coded value, with the most significant bit then taking either a value 0 or a value 1 depending on an encoding bit. This encoding bit is changed to show which loop through the write pointer FIFO 210 is occurring, and hence assuming that the read pointer is initially at location 0, this encoding bit will remain as a 0 value as the location of the read pointer steps through locations 0, 1 and 2, after which a further increment of the read pointer will return it to location 0, but at this point the encoding bit for the most significant bit will change to a 1 value. The encoding bit will then remain at 1 whilst the read pointer increments through locations 0, 1 and 2, and when the read pointer is subsequently incremented to return to location 0, this encoding bit will then return to 0 for the next iteration. This final encoding bit hence enables a determination to be made when comparing the write pointer and the read pointer as to whether the write pointer is ahead of the read pointer, or the read pointer is ahead of the write pointer. The gray coded value produced by the gray coding logic 385 is routed into the first clock domain via the metastability synchronisation registers 390, whereafter the ungray coding logic 395 then decodes the gray coded value in order to output the value of the RPWPFIFO to the unlike-signed addition logic 355. The WPWPFIFO generation logic 350 hence receives a signal indicating the difference between the WPWPFIFO and the RPWPFIFO values. Provided that that value is two or less, the WPWPFIFO generation logic hence knows that is has sufficient space to write the new write data (i.e. the current value of WPMAINFIFO) into the write pointer FIFO 210, and accordingly can conclude that the write pointer FIFO 520 is not full. If the write pointer FIFO is determined to be fall, the process waits at step 520 until there is sufficient space to write the new data into a location of the write pointer FIFO 210, but once it is determined that the write pointer FIFO 210 is not full, the process proceeds to step 525, where the WPMAINFIFO value is written as data into one of the registers 310 of the write pointer FIFO at a location indicated by WPWPFIFO. The WPWPFIFO value is output by the WPWPFIFO generation logic 350. The process then proceeds to step 530, where the WPWPFIFO value is gray coded by the gray coding logic 370, and then output to the second clock domain via the two metastability synchronisation registers 375. The process then proceeds to point 535 and in addition loops back to step 505 to await receipt of new data over path 220. Once the data has been written into the main FIFO 200, and the associated WPMAINFIFO value has been stored into the write pointer FIFO 210, then the main write pointer generation logic 330 will increment the value of WPMANFIFO to identify the location immediately following the new data that has been written into the main FIFO 200 in preparation for receipt of the next block of data over path 220. As will be appreciated, since the amount of data that can be written is variable, the amount by which the WPMAINFIFO value is incremented will be variable. Similarly, the WPWPFIFO generation logic 350 will increment the value of WPWPFIFO by one location in readiness for storing the next WPMAINFIFO value in the write pointer FIFO 210. Considering now FIG. 3B, which illustrates a sequence of steps occurring in the second clock domain, the process proceeds from point 535 to step 540, where the ungray coding logic 380 decodes the gray coded WPWPFIFO value as received from the first clock domain in order to produce the value of WPWPFIFO for inputting to the unlike-signed addition logic 365. The process then proceeds to step 545, there the RPWPFIFO generation logic 360 determines whether the value of WPWPFIFO has been updated. This can be determined based on the output from the unlike-signed addition logic 365 which receives at its input the current value of RPWPFIFO and the WPWPFIFO value received from the ungray coding logic 380. In particular, if the value of RPWPFIFO and WPWPFIFO are the same, this will indicate that the WPWPFIFO value has not been updated, and that there is no new data to read from the write pointer FIFO 210. If this is the case, then the process loops back to step 540 to await receipt of a further WPWPFIFO value from the ungray coding logic 380. However, assuming at step 545 it is determined that the value of WPWPFIFO has been updated, then the process proceeds to step 550, where the RPWPFIFO generation logic 360 generates a new RPWPFIFO value. This will typically be done by incrementing the previous value of RPWPFIFO. Thereafter, at step 555, the new value of RPWPFIFO is input to the multiplexer 315, to cause the relevant data to be read from the write pointer FIFO 210 and output to the unlike-signed addition logic 345. This read data actually provides a value of WPWPFIFO. At step 560, it is then determined by the main write pointer generation logic 340 whether there is any data to be read in the main FIFO 200. As can be seen from FIG. 2, the unlike-signed addition logic 345 receives as one of its inputs the current value of RPMAINFIFO, and at its other input the data read from the write pointer FIFO (i.e. a value of WPMAINFIFO). If these two values are the same, then this will indicate that there is no data to be read from the main FIFO, and accordingly the process will return to step 540, where the process will wait until there is data in the main FIFO to be read. Assuming it is determined at step 560 that there is data in the main FIFO to be read, then at step 565 the main write pointer generation logic 340 generates a new value for RPMAINFIFO based on the WPFIFO value as read. Typically, this is done by incrementing the RPMAINFIFO value to indicate a start location for the reading of data. However, the number of bytes of data to be read in any particular cycle from the main FIFO 200 is dependent on how full the main FIFO is, which is indicated by the difference between the WPMAINFIFO value and the RPMAINFIFO value as determined by the output from the unlike-signed addition logic 345. In particular, in one embodiment, it is possible to read between 0 and 4 bytes of data in one cycle depending on how full the main FIFO 200 is. This indication of how many bytes to read is in one embodiment provided as part of the RPMAINFIFO value produced by the main write pointer generation logic 340. Following step 565, the data is then read from the main FIFO 200 by controlling the multiplexer 305 using the RPMAINFIFO value generated by the main write pointer generation logic 340. The process then returns to step 540 to await receipt by the ungray coding logic 380 of a new gray coded WPWPFIFO value. In addition, the process proceeds to point 575. As shown in FIG. 3C, which indicates some further steps performed in the second clock domain, the process proceeds from point 575 to step 580, where the WPRPFIFO generation logic 400 determines whether the read pointer FIFO 205 is full. This determination is made since some write data will now have been received by the read pointer FIFO 205, providing the new value of RPMAINFIFO. As can be seen by comparison of the lower portion of FIG. 2 with the upper portion of FIG. 2, the analysis performed by the logic 400, 405 is analogous to that performed by the logic 350, 355 described earlier. In particular, the unlike-signed addition logic 405 receives at its inputs the current WPRPFIFO value, and a current RPRPFIFO value as returned from the first clock domain to the second clock domain via the gray coding logic 435, metastability synchronisation registers 440 and ungray coding logic 445. Assuming it is determined by the WPRPFIFO generation logic 400 that the read pointer FIFO is not full, then the process proceeds to step 585, where the RPMAINFIFO value is stored into one of the registers 320 of the read pointer FIFO 205 at a location indicated by the value of WPRPFIFO generated by the WPRPFIFO generation logic 400. This WPRPFIFO value is then also routed to the gray coding logic 420, where at step 590 it is gray coded and output to the metastability synchronisation registers 425. At this point, the value of WPRPFIFO can be incremented in preparation for receipt of the next write data value, and the RPMAINFIFO value can be incremented by an amount dependent on the number of bytes read from the main FIFO 200. The process then returns to step 580 and also proceeds to point D 595. As shown in FIG. 3D, which shows a sequence of steps performed in the first clock domain, the ungray coding logic 430 then decodes the gray coded WPRPFIFO value as received from the second clock domain, and outputs that value as an input to the unlike-signed addition logic 415. Then, at step 605, it is determined whether the WPRPFIFO value has been updated. This determination is made by the RPRPFIFO generation logic 410 based on the output from the unlike-signed addition logic 415, in an analogous way to the determination made by the RPWPFIFO generation logic 360 discussed earlier. If the WPRPFIFO is determined not to have been updated, then this indicates that there is no data to be read from the read pointer FIFO 205, and the process returns to step 600. However, assuming it is determined that the WPRPFIFO value has been updated, then the process proceeds to step 610, where a new RPRPFIFO value is generated by the RPRPFIFO generation logic 410. This value will typically be an incremented version of the previous value. Then, the process proceeds to step 615, where the RPRPFIFO value generated at step 610 is used to control the multiplexer 325 to read data from the read pointer FIFO 205, this data providing a value of RPMAINFIFO for inputting to the unlike-signed addition logic 335. The process then proceeds to point 500, which is the starting point for FIG. 3A. It will be appreciated that the new asynchronous FIFO apparatus as discussed above with reference to FIGS. 1 to 3 may be used in a variety of instances where it is required to pass data in a data processing apparatus between two asynchronous clock domains. An illustrative example of a data processing apparatus in which this new asynchronous FIFO apparatus can be used is illustrated in FIG. 4. FIG. 4 schematically illustrates a data processing system 2 providing an on-chip tracing mechanism. An integrated circuit 4 includes a microprocessor core 6, a cache memory 8, an on-chip trace module 10 and an on-chip trace buffer 12. The integrated circuit 4 is connected to an external memory 14 which is accessed when a cache miss occurs within the cache memory 8. A general purpose computer 16 is coupled to the on-chip trace module 10 and the on-chip trace buffer 12 and serves to recover and analyse a stream of tracing data from these elements using software executing upon the general purpose computer 16. It is often the case that the processor core 6 may, during operation, need to access more data processing instructions and data than there is actually space for in the external memory 14. For example, the external memory 14 may have a size of 1 MB, whereas the processor core 6 might typically be able to specify 32-bit addresses, thereby enabling 4 GB of instructions and data to be specified. Accordingly, all of the instructions and data required by the processor core 6 are stored within external storage 18, for example a hard disk, and then when the processor core 6 is to operate in a particular state of operation, the relevant instructions and data for that state of operation are loaded into the external memory 14. FIG. 5 is a block diagram illustrating in more detail the components provided within the on-chip trace module of FIG. 4. The on-chip trace module 10 is arranged to receive over path 105 data indicative of the processing being performed by the processor core 6. With reference to FIG. 4, this may be received from the bus 20 connecting the core 6, cache 8, and on-chip trace-module 10 (such data for example indicating instructions and/or data presented to the core 6, and data generated by the core), along with additional control-type data received directly from the core over bus 22 (for example, an indication that the instruction address is being indexed, an indication that a certain instruction failed its condition codes for some reason, etc). As will be appreciated by those skilled in the art, in certain embodiments both types of data could be passed to the trade module 10 over a single bus between the trace module 10 and the core 6 (rather than using two buses 20, 22). The sync logic 100 is arranged to convert the incoming signals into internal versions of the signals more appropriate for use within the on-chip trace module. These internal versions are then sent to the trigger 110 and the trace generation block 120, although it will be appreciated that the trigger 110 and the trace generation block 120 will not necessarily need to receive the same signals. Fundamentally, the trigger 110 needs to receive data relating to triggerable events, for example instruction addresses, data values, register accesses, etc. The trace generation block 120 needs to receive any data that would need to be traced dependent on the enable signals issued by the trigger 110. The on-chip trace module 10 further incorporates a register bank 180 which is arranged to receive configuration information over path 125 from the general purpose computer 16, whose contents can be read by the components of the on-chip trace module 10 as required. Whenever the trigger 110 detects events which should give rise to the generation of a trace stream, it sends an enable signal over path 135 to the trace generation logic 120 to turn the trace on and off. The trace generation logic reacts accordingly by outputting the necessary trace data to the FIFO 130 over path 145. It will be appreciated that a variety of enable signals may be provided over path 135, to identify the type of signals which should be traced, for example trace only instructions, trace instructions and data, etc. The trace signals are then drained through an output trace port from the FIFO 130 to the trace buffer 12 via path 150. Typically, any trace signals issued over path 150 to the trace buffer are also accompanied by trace valid signals over path 140 indicating whether the output trace is valid or not. A trace valid signal would typically be set to invalid if the associated trace module has no trace data to issue in that clock cycle. In one embodiment of the present invention, the FIFO 130 may take the form of that FIFO apparatus described earlier with reference to FIG. 2. This can be useful, for example, if the integrated circuit 4 has asynchronous clock domains provided therein, such as would for example be the case if Intelligent Energy Management (IEM) techniques were employed, where the voltage supply to particular components of a data processing apparatus may be reduced during periods of inactivity in order to save energy consumption within the data processing apparatus. Since trace data by its nature is often quite bursty, it cannot be guaranteed that the same number of bits of trace data will be written per clock cycle into the FIFO 130, and hence the use of a FIFO apparatus as discussed earlier with reference to FIG. 2 allows the trace data to continue to be stored and read out correctly even in the presence of asynchronous clock domains between the core 6 and trace buffer 12. From the above description of an embodiment of the present invention, it will be appreciated that the asynchronous FIFO apparatus described herein enables data to be passed between a first clock domain and an asynchronous second clock domain in situations where in at least one of the two clock domains the amount of data accessible per clock cycle in the FIFO apparatus is variable. This will be particularly beneficial in forthcoming data processing apparatus designs, where it is becoming more and more common for different asynchronous clock domains to exist within the same data processing apparatus. Although a particular embodiment of the invention has been described herein, it will be apparent that the invention is not limited thereto, and that many modifications and additions may be made within the scope of the invention. For example, various combinations of the features of the following dependent claims could be made with the features of the independent claims without departing from the scope of the present invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to asynchronous FIFO (First-In-First-Out) memories, and in particular to an improved asynchronous FIFO apparatus and method for passing data between a first clock domain and a second clock domain of a data processing apparatus. 2. Description of the Prior Art It is known to use an asynchronous FIFO memory to pass data between first and second clock domains in a data processing apparatus, for example a microchip design/implementation, such an approach typically being used if the first clock domain is asynchronous with respect to the second clock domain (i.e. the clock frequency in the first clock domain is asynchronous with respect to the clock frequency in the second clock domain). However, current designs of asynchronous FIFO memories only operate correctly if there are a constant number of input bits of data into the FIFO memory (herein the term “FEFO” will sometimes be used as an abbreviation for “FIFO memory”) in each clock cycle in which it is desired to write data to the FIFO. Similarly, on the output side of the FIFO, current designs of asynchronous FIFOs only work if there is a constant number of output bits of data from the FIFO in each clock cycle in which it is desired to read data from the FIFO. This restriction is required due to the asynchronous nature of the two clock domains, and the need to ensure that any pointer value passed between the two clock domains will be correctly read in the target domain. In particular, considering the example of the write side of the FIFO, if a constant number of input bits (say for example one byte) is written into the FIFO during a particular clock circle, then this enables the write pointer to the incremented by a predetermined amount (in this example one). A gray coding process can then be applied to the write pointer before it is passed into the read domain, and because the write pointer is always incremented by the same predetermined amount, this will ensure that the gray coded write pointer only differs from its previous value by one bit. This ensures that when that gray coded write pointer is sampled in the read domain, it is only possible for the read domain to either get the correct current value, or the previous value, of the write pointer, thus avoiding any mis-reading of the write pointer. Accordingly, it is then possible in the read domain to correctly read the associated data from the FIFO. It is important to note that the above gray coding process only works correctly when a constant number of bits of data are written into the FIFO in each cycle in which it is desired to write data, since otherwise more than one bit of the gray coded write pointer could be different from the previous gray coded write pointer, which will compromise the integrity of the value read in the read domain. For example, in the above instance, given the asynchronous nature of the read clock domain to the write clock domain, it may be the case that when the read clock domain samples the gray coded write pointer, only one of the bits will have changed, which the read domain would then interpret as a valid gray coded write pointer, even though it is in fact incorrect. Due to recent developments in data processing designs, it is becoming more commonplace for different asynchronous clock domains to exist within a data processing apparatus. As an example, there has recently been much development in the area of Intelligent Energy Management (IEM), where the voltage supply to particular components of a data processing apparatus may be reduced during periods of inactivity in order to save energy consumption within the data processing apparatus. The implementation of such IEM techniques can give rise to the presence of multiple asynchronous clock domains within the design of a particular data processing apparatus. Whilst current asynchronous FIFO designs can be used to pass data between these differing clock domains in situations where the above constraints on input bits of data and output bits of data are observed, there are a number of instances where certain elements of the data processing apparatus will produce data in a non-constant, or bursty, manner, and current asynchronous FIFO designs will not enable such data to be passed between two asynchronous clock domains, due to the earlier described restrictions required by such asynchronous FIFO designs. Accordingly, it is an object of the present invention to provide an improved asynchronous FIFO design which alleviates the above-mentioned problems. | <SOH> SUMMARY OF THE INVENTION <EOH>Viewed from a first aspect, the present invention provides an asynchronous FIFO apparatus for a data processing apparatus having a first clock domain and a second clock domain, the first clock domain being asynchronous with respect to the second clock domain, the asynchronous FIFO apparatus being operable to pass data between the first clock domain and the second clock domain and comprising: a main FIFO operable to store said data to be passed between the first clock domain and the second clock domain, the main FIFO being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; an auxiliary FIFO associated with said one of said first and second clock domains and operable to store the access pointer used to access the main FIFO from that clock domain, the access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer; and routing logic operable to pass the auxiliary access pointer to the other of said first and second clock domains to enable that other of the first and second clock domains to retrieve the access pointer stored in the auxiliary FIFO. In accordance with the present invention, an asynchronous FIFO apparatus is provided which includes a main FIFO for storing data to be passed between a first clock domain and a second clock domain, and an auxiliary FIFO associated with one of the domains in which the amount of data accessible per clock cycle in the main FIFO is variable. In particular, for that clock domain, the auxiliary FIFO is used to store the access pointer used to access the main FIFO, this access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer. Then, in accordance with the present invention, routing logic is used to pass the auxiliary access pointer to the other clock domain to enable that other clock domain to retrieve the access pointer stored in the auxiliary FIFO. Since the amount of data accessible per clock cycle in the main FIFO is variable, this means that the associated changes in the access pointer for the main FIFO are also variable. However, the present invention takes advantage of the fact that even if the changes to the access pointer are variable, the access pointer itself will always be specified by a constant number of bits, and accordingly if the access pointer is stored in the auxiliary FIFO, then the auxiliary access pointer can always be incremented by a constant amount. Accordingly, this enables the auxiliary access pointer to be passed between the two clock domains in a manner which allows it to be accurately sampled in the recipient clock domain. It will be appreciated that, depending on the number of locations within the auxiliary FIFO, and the way in which the auxiliary access pointers are arranged, it may be possible to constrain the auxiliary access pointers so that any incremented auxiliary access pointer only differs from its previous value by one bit, in which event the auxiliary access pointer can be directly passed by the routing logic to the other clock domain. However, in one embodiment, the routing logic performs a coding on the auxiliary access pointer in order to generate a coded auxiliary access pointer for passing to the other of said first and second clock domains. The coding is chosen in such a way as to ensure that any new coded auxiliary access pointer only differs from a preceding coded auxiliary access pointer by one bit, thus ensuring integrity in the reading of the coded auxiliary access pointer by the recipient clock domain. In one particular embodiment, the routing logic performs a gray coding operation on the auxiliary access pointer in order to generate a gray coded auxiliary access pointer. It has been found that gray coding is a particularly efficient technique for coding the auxiliary access pointer so that when that pointer is sampled in the recipient clock domain, it is only possible for it to be either the current value or the previous value of the gray coded auxiliary access pointer. It will be appreciated that the manner in which the asynchronous FIFO apparatus interfaces between the first clock domain and the second clock domain can take a variety of forms. However, in one embodiment, the main FIFO is accessible from the first clock domain under the control of a write access pointer in order to write data into the main FIFO, and the main FIFO is accessible from the second clock domain under the control of a read access pointer in order to read data from the main FIFO. Hence, in this embodiment, data is written into the FIFO from elements of the data processing apparatus provided in the first clock domain, and then data is read from the FIFO by elements of the data processing apparatus provided in the second clock domain. It will be appreciated that the clock domain in which the amount of data accessible per clock cycle in the main FIFO is variable can be either the first clock domain, the second clock domain, or indeed both clock domains. In one embodiment, for said first clock domain the amount of data writeable into the main FIFO per clock cycle is variable; the auxiliary FIFO is a write pointer FIFO operable to store the write access pointer used to access the main FIFO from the first clock domain; and the routing logic is operable to pass the auxiliary access pointer to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO to be read. Hence, in accordance with this embodiment, write pointers are stored in the auxiliary FIFO, and routing of the auxiliary access pointer to the second clock domain enables the write access pointer to be retrieved, and for read logic in the second clock domain to then cause the associated data stored in the main FIFO to be read. In an alternative embodiment, for said second clock domain the amount of data readable from the main FIFO per clock cycle is variable; the auxiliary FIFO is a read pointer FIFO operable to store the read access pointer used to access the main FIFO from the second clock domain; and the routing logic is operable to pass the auxiliary access pointer to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO is full. In accordance with this embodiment, a read access pointer is stored within the auxiliary FIFO, and routing of the auxiliary access pointer to the first clock domain enables the read access pointer to be retrieved, and for write control logic in the first clock domain to then determine, in response to the read access pointer, whether the main FIFO is full. Typically, if the main FIFO is full, the write control logic will prevent any new data being written into the main FIFO until space is available, in order to avoid any data being overwritten in the main FIFO that has not yet been read in the second clock domain. In an alternative embodiment, for both of said first and second clock domains the amount of data accessible per clock cycle is variable, the auxiliary FIFO comprising first and second auxiliary FIFOs, each with associated routing logic; the first auxiliary FIFO being a write pointer FIFO operable to store the write access pointer used to access the main FIFO from the first clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the write pointer FIFO to the second clock domain to enable the second clock domain to retrieve the write access pointer stored in the write pointer FIFO; the asynchronous FIFO apparatus further comprising read logic in the second clock domain and operable in response to the write access pointer to cause the associated data stored in the main FIFO to be read; the second auxiliary FIFO being a read pointer FIFO operable to store the read access pointer used to access the main FIFO from the second clock domain, and its associated routing logic being operable to pass the auxiliary access pointer of the read pointer FIFO to the first clock domain to enable the first clock domain to retrieve the read access pointer stored in the read pointer FIFO; the asynchronous FIFO apparatus further comprising write control logic in the first clock domain and operable in response to the read access pointer to determine whether the main FIFO is full. In accordance with this embodiment, both a write pointer FIFO and a read pointer FIFO are provided, each having associated routing logic, this hence enabling write pointers to be reliably passed between the first and second clock domains via an associated auxiliary access pointer, and also for read access pointers to be reliably passed from the second clock domain to the first clock domain via associated auxiliary access pointers. In this embodiment, both the amount of data writeable to the main FIFO per clock cycle is variable, and the amount of data readable from the main FIFO per clock cycle is variable. Viewed from a second aspect, the present invention provides a data processing apparatus comprising: a first element operating in a first clock domain; a second element operating in a second clock domain; and an asynchronous FIFO apparatus in accordance with the first embodiment of the present invention, operable to pass data between the first element and the second element. In one particular embodiment, the data processing apparatus further comprises: a trace module operable to produce trace data indicative of the activity of the first element, the trace module including said asynchronous FIFO apparatus; wherein the main FIFO is accessible from the first clock domain under the control of a write access pointer in order to write into the main FIFO the trace data, and the main FIFO is accessible from the second clock domain under the control of a read access pointer in order to read from the main FIFO the trace data for passing to the second element. Hence, in accordance with: this embodiment, an asynchronous FIFO apparatus is provided within a trace module, with the data stored within the main FIFO being trace data. In one particular implementation of such an embodiment, the first element may be a processor core, and the second element may be a trace buffer used to store trace data prior to output to a trace analysis tool. In one embodiment, a power supply voltage to the first element is variable, and a clock frequency of the first clock domain is operable to change in dependence on the power supply voltage. In one particular implementation of such an embodiment, the data processing apparatus may incorporate Intelligent Energy Management (EEM) logic which enables the power supply voltage to the first element to be reduced when the first element is less busy, in order to provide energy consumption savings. This variation in the power supply voltage has a knock-on effect on the clock frequency within the first clock domain, and this in turn causes a variation in the rate of writing of trace data into the main FIFO. Viewed from a second aspect, the present invention provides a method of passing data between a first clock domain and a second clock domain of a data processing apparatus, the first clock domain being asynchronous with respect to the second clock domain, the method comprising the steps of: (a) storing within a main FIFO said data to be passed between the first clock domain and the second clock domain, the main FIFO being accessible from each of the first clock domain and the second clock domain under the control of an access pointer associated with that clock domain, for one of said first and second clock domains the amount of data accessible per clock cycle being variable; (b) storing within an auxiliary FIFO associated with said one of said first and second clock domains the access pointer used to access the main FIFO from that clock domain, the access pointer being stored at a location of the auxiliary FIFO specified by an auxiliary access pointer; (c) passing the auxiliary access pointer to the other of said first and second clock domains; and (d) retrieving, at the other of the first and second clock domains, the access pointer stored in the auxiliary FIFO. | 20040330 | 20080101 | 20051006 | 60240.0 | 0 | BOCURE, TESFALDET | ASYNCHRONOUS FIFO APPARATUS AND METHOD FOR PASSING DATA BETWEEN A FIRST CLOCK DOMAIN AND A SECOND CLOCK DOMAIN OF A DATA PROCESSING APPARATUS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,314 | ACCEPTED | High efficiency power converter | A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings. | 1. A power converter, comprising: a primary transformer winding circuit having at least one primary winding; a secondary transformer winding circuit comprising: at least one secondary winding coupled to the at least one primary winding; a controlled rectifier transistor, each primary winding having a voltage waveform with transition times which are short relative to the on-state and off-state times of the controlled rectifier; and a capacitive divider circuit, a signal controlling the controlled rectifier transistor being derived from the capacitive divider circuit. 2. A power converter as claimed in claim 1 further comprising a circuit to determine the DC component of the signal controlling the controlled rectifier transistor. 3. A power converter as claimed in claim 2 wherein the dc component of the signal is adjusted to provide regulation. 4. A power converter as claimed in claim 3 wherein a feedback circuit sets the DC component of the signal controlling the controlled rectifier transistor. 5. A power converter as claimed in claim 3 wherein the power converter provides multiple outputs, the DC component being adjusted to set an output level of at least one of the outputs. 6. A power converter as claimed in claim 1 wherein a control terminal of the controlled rectifier transistor is connected directly to the capacitive divider circuit. 7. A power converter as claimed in claim 1 wherein the capacitive divider circuit includes at least one capacitor external from the controlled rectifier transistor. 8. A power converter as claimed in claim 1 wherein one of two capacitors composing the capacitive divider circuit is substantially entirely intrinsic parasitic capacitance. 9. A power converter as claimed in claim 1 wherein the capacitive divider circuit is coupled to a terminal of a secondary winding of a transformer in the power converter. 10. A power converter as claimed in claim 1 wherein the controlled rectifier transistor is in parallel with an uncontrolled rectifier. 11. A power converter as claimed in claim 10 wherein the uncontrolled rectifier is a body diode in the controlled rectifier transistor. 12. A power converter as claimed in claim 1 wherein a DC component of the signal is adjusted in response to a condition of the power converter. 13. A power converter as claimed in claim 1 wherein a DC component of the signal is adjusted to a state where only the uncontrolled rectifier carries current. 14. A power converter as claimed in claim 1 wherein a DC component of the signal is adjusted to a state where the controlled rectifier transistor is capable of only unidirectional current flow for a period of time. 15. A method for providing rectification in a power converter, comprising: controlling a voltage waveform across a primary transformer winding; rectifying an AC waveform by a controlled rectifier transistor in a secondary transformer winding circuit, each primary winding having a voltage waveform with transition times which are short relative to the on-state and off-state times of the controlled rectifier; and capacitively dividing the AC waveform to derive a control signal used to control the controlled rectifier transistor. 16. A method as claimed in claim 15 further including determining a DC component of the control signal. 17. A method as claimed in claim 16 further including adjusting the DC component of the control signal to provide regulation. 18. A method as claimed in claim 17 wherein adjusting the DC component of the control signal includes feeding back a feedback signal derived from the regulated output of the power converter. 19. A method as claimed in claim 17 wherein (i) the power converter provides multiple outputs and (ii) adjusting the DC component sets an output level of at least one of the outputs. 20. A method as claimed in claim 15 further including rectifying the AC waveform in an uncontrolled manner. 21. A method as claimed in claim 15 wherein capacitively dividing the AC waveform is done, in part, external from a component used for rectifying the AC waveform in a controlled manner. 22. A method as claimed in claim 15 wherein capacitively dividing the AC waveform is done, in part, internal to a component having inherent parasitic capacitance used for rectifying the AC waveform in a controlled manner. 23. A method as claimed in claim 15 wherein a DC component of the control signal is adjusted in response to a condition of the power converter. 24. A method as claimed in claim 15 wherein a DC component of the control signal is adjusted to a state where only the uncontrolled rectifier carries current. 25. A method as claimed in claim 15 wherein a DC component of the control signal is adjusted to a state where the controlled rectifier transistor is capable of only unidirectional current flow for a period of time. 26. A power converter comprising: a primary transformer winding circuit having at least one primary winding; a secondary transformer winding circuit comprising: at least one secondary winding coupled to the at least one primary winding; means for rectifying an AC waveform by a controlled rectifier transistor, each primary winding having a voltage waveform with transition times which are short relative to the on-state and off-state times of the controlled rectifier; and means for capacitively dividing the AC waveform to derive a control signal used to control the controlled rectifier transistor. | RELATED APPLICATIONS This application is a continuation of application Ser. No. 10/359,457, filed Feb. 5, 2003, which continuation of application Ser. No. 09/821,655, filed Mar. 29, 2001, now U.S. Pat. No. 6,594,159, which is a divisional of application Ser. No. 09/417,967, filed Oct. 13, 1999, now U.S. Pat. No. 6,222,742, which is a divisional of Ser. No. 09/012,475, filed Jan. 23, 1998, now U.S. Pat. No. 5,999,417, which claims the benefit of U.S. Provisional Application 60/036,245 filed Jan. 24, 1997. The entire teachings of the above applications are incorporated herein by reference. BACKGROUND OF THE INVENTION This invention pertains to switching power converters. A specific example of a power converter is a DC-DC power supply that draws 100 watts of power from a 48 volt DC source and converts it to a 5 volt DC output to drive logic circuitry. The nominal values and ranges of the input and output voltages, as well as the maximum power handling capability of the converter, depend on the application. It is common today for switching power supplies to have a switching frequency of 100 kHz or higher. Such a high switching frequency permits the capacitors, inductors, and transformers in the converter to be physically small. The reduction in the overall volume of the converter that results is desirable to the users of such supplies. Another important attribute of a power supply is its efficiency. The higher the efficiency, the less heat that is dissipated within the supply, and the less design effort, volume, weight, and cost that must be devoted to remove this heat. A higher efficiency is therefore also desirable to the users of these supplies. A significant fraction of the energy dissipated in a power supply is due to the on-state (or conduction) loss of the diodes used, particularly if the load and/or source voltages are low (e.g. 3.3, 5, or 12 volts). In order to reduce this conduction loss, the diodes are sometimes replaced with transistors whose on-state voltages are much smaller. These transistors, called synchronous rectifiers, are typically power MOSFETs for converters switching in the 100 kHz and higher range. The use of transistors as synchronous rectifiers in high switching frequency converters presents several technical challenges. One is the need to provide properly timed drives to the control terminals of these transistors. This task is made more complicated when the converter provides electrical isolation between its input and output because the synchronous rectifier drives are then isolated from the drives of the main, primary side transistors. Another challenge is the need to minimize losses during the switch transitions of the synchronous rectifiers. An important portion of these switching losses is due to the need to charge and discharge the parasitic capacitances of the transistors, the parasitic inductances of interconnections, and the leakage inductance of transformer windings. SUMMARY OF THE INVENTION Various approaches to addressing these technical challenges have been presented in the prior art, but further improvements are needed. In response to this need, a new power circuit topology designed to work with synchronous rectifiers in a manner that better addresses the challenges is presented here. In preferred embodiments of the invention, a power converter comprises a power source and a primary transformer winding circuit having at least one primary winding connected to the source. A secondary transformer winding circuit has at least one secondary winding coupled to the at least one primary winding. Plural controlled rectifiers, such as voltage controlled field effect transistors, each having a parallel uncontrolled rectifier, are connected to a secondary winding. Each controlled rectifier is turned on and off in synchronization with the voltage waveform across a primary winding to provide an output. Each primary winding has a voltage waveform with a fixed duty cycle and transition times which are short relative to the on-state and off-state times of the controlled rectifiers. A regulator regulates the output while the fixed duty cycle is maintained. In the preferred embodiments, first and second primary transformer windings are connected to the source and first and second primary switches are connected in series with the first and second primary windings, respectively. First and second secondary transformer windings are coupled to the first and second primary windings, respectively. First and second controlled rectifiers, each having a parallel uncontrolled rectifier, are in series with the first and second secondary windings, respectively. A controller turns on the first and second primary switches in opposition, each for approximately one half of the switching cycle with transition times which are short relative to the on-state and off-state times of the first and second controlled rectifiers. The first and second controlled rectifiers are controlled to be on at substantially the same times that the first and second primary switches, respectively, are on. In a system embodying the invention, energy may be nearly losslessly delivered to and recovered from capacitors associated with the controlled rectifiers during their transition times. In the preferred embodiments, the first primary and secondary transformer windings and the second primary and secondary transformer windings are on separate uncoupled transformers, but the two primary windings and two secondary windings may be coupled on a single transformer. Preferably, each controlled rectifier is turned on and off by a signal applied to a control terminal relative to a reference terminal of the controlled rectifier, and the reference terminals of the controlled rectifiers are connected to a common node. Further, the signal that controls each controlled rectifier is derived from the voltage at the connection between the other controlled rectifier and its associated secondary winding. Regulation may be through a separate regulation stage which in one form is on the primary side of the converter as part of the power source. Power conversion may then be regulated in response to a variable sensed on the primary side of the converter. Alternatively, the regulator may be a regulation stage on the secondary side of the converter, and power conversion may be regulated by control of the controlled rectifiers. Specifically, the on-state voltage of a controlled rectifier may be made larger than its minimum value to provide regulation, or the on-state duration of a controlled rectifier may be shorter than its maximum value to provide regulation. The preferred systems include reset circuits associated with transformers for flow of magnetizing current. The energy stored in the magnetizing inductance may be recovered. In one form, the reset circuit comprises a tertiary transformer winding, and in another form it comprises a clamp. In preferred embodiments, the power source has a current fed output, the current fed output characteristic of the power source being provided by an inductor. Alternatively, the power source may have a voltage-fed output where the voltage-fed output characteristic of the power source is provided by a capacitor. In either case, the characteristics may alternatively be provided by active circuitry. With the preferred current-fed output, the primary switches are both turned on during overlapping periods, and the overlapping periods may be selected to achieve maximum efficiency. With the voltage-fed output, the primary switches are both turned off during overlapping periods. Additional leakage or parasitic inductance may be added to the circuit to accommodate an overlap period. In one embodiment, a signal controlling a controlled rectifier is derived with a capacitive divider circuit. A circuit may determine the DC component of the signal controlling the controlled rectifier, and the DC component of the signal may be adjusted to provide regulation. In accordance with another aspect of the invention, an ORing controlled rectifier connects the converter's output to an output bus to which multiple converter outputs are coupled, and the ORing controlled rectifier is turned off if the power converter fails. Preferably, the signal controlling the ORing controlled rectifier is derived from one or more secondary windings. The ORing controlled rectifier is turned on when the converter's output voltage approximately matches the bus voltage. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. FIG. 1 is a block diagram illustrating a preferred embodiment of the invention. FIG. 2 is a schematic of an embodiment of the invention with synchronous rectifiers replaced by diodes. FIG. 3 is an illustration of a preferred embodiment of the invention with the controlled rectifiers and parallel uncontrolled rectifiers illustrated. FIG. 4 illustrates an alternative location of the synchronous rectifiers in the circuit of FIG. 3. FIG. 5 illustrates the circuit of FIG. 3 with important parasitic capacitances and inductances illustrated. FIG. 6A illustrates another embodiment of the invention with the tertiary winding connected to the primary side. FIG. 6B illustrates another embodiment of the invention with a voltage fed isolation stage. FIG. 7 illustrates a secondary circuit having capacitive dividers to divide the voltages applied to the control terminals of the controlled rectifiers. FIG. 8 shows an alternative embodiment in which the output is regulated by controlling the voltage applied to the control terminals of the controlled rectifiers. FIG. 9 illustrates an embodiment of the invention in which the primary windings are tightly coupled. FIG. 10 illustrates the use of an ORing controlled rectifier to couple the power converter to an output bus. DETAILED DESCRIPTION OF THE INVENTION A description of preferred embodiments of the invention follows. One embodiment of the invention described herein pertains to an electrically isolated DC-DC converter that might be used to deliver power at a low DC voltage (e.g. 5 volts) from a DC source such as a battery or a rectified utility. In such a converter a transformer is used to provide the electrical isolation and to provide a step-down (or step-up) in voltage level according to its turns-ratio. Switches in the form of power semiconductor transistors and diodes are used in conjunction with capacitors and inductors to create the conversion. A control circuit is typically included to provide the drive signals to the transistors' control terminals. When the switching frequency is high (e.g. 100 kHz and above) it is typical today to use power MOSFETs and Schottky diodes for the converter's switches since these majority carrier devices can undergo faster switch transitions than minority carrier devices such as power bipolar transistors and bipolar diodes. Most DC-DC converters are designed to provide regulation of their output voltage in the face of input voltage and output current variations. For example, a converter might need to maintain a 5 volt output (plus or minus a few percent) as its input varies over the range of 36 to 75 volts and its output current ranges from 1 to 25 amps. This ability to provide regulation is usually the result of the power circuit's topology and the manner in which its switching devices are controlled. Sometimes the regulation function is supplied by (or augmented with) a linear regulator. FIG. 1 shows a block diagram of a DC-DC converter that represents one embodiment of the invention. It shows a two stage converter structure where the power first flows through one stage and then through the next. One stage provides the regulation function and the other provides the electrical isolation and/or step-down (or step-up) function. In this embodiment the regulation stage is situated before the isolation stage, but this ordering is not necessary for the invention. Notice also that the block diagram shows a control function. As mentioned, the purpose of this control function is to determine when the transistors in the power circuit will be turned on and off (or to determine the drive of a linear regulator). To aid in this function the control circuit typically senses voltages and currents at the input, at the output, and/or within the power circuit. FIG. 2 shows one way to implement the two power stages represented in the block diagram of FIG. 1. In this figure diodes, rather than synchronous rectifiers, are used to simplify the initial description of the circuit's operation. The topology of the regulation stage is that of a “down converter”. This canonical switching cell has a capacitor, CIN, a transistor, QR, a diode, DR, and an inductor, L. Regulation is by control of the duty cycle of the transistor QR in response to one or more parameters sensed in the circuit. In a well known manner the regulation stage can be modified by providing higher order filters at its input and output, by replacing the diode with a synchronous rectifier, by adding resonant elements to create a “multi-resonant” converter and the like. The topology of the isolation stage shown in FIG. 2 has two transformers that are not, in this case, coupled. Each of these transformers T1 and T2 has three windings: a primary winding T1PRI, T2PRI; a secondary winding T1SEC, T2SEC; and a tertiary winding T1TER, T2TER. The transformer windings are connected through MOSFETs Q1 and Q2 on the primary windings and through diodes D1, D2, D3, and D4 on the secondary and tertiary windings. The stage is “current-fed”, in this case by the inductor L from the output of the regulation stage. By this it is meant that the current flowing into the primary side of the isolation stage is held relatively constant over the time frame of the switching cycle. It also means that the voltage across the primary side of the isolation stage is free to have large, high frequency components. The output filter is simply a capacitor COUT whose voltage is relatively constant over the time frame of the switching cycle. Additional filtering stages could be added to this output filter in a known manner. The operation of the isolation stage proceeds in the following manner. First, for approximately one half of the switching cycle, transistor Q1 is on and Q2 is off. The current flowing through inductor L therefore flows through the primary winding of transformer T1 , and a corresponding current (transformed by the turns ratio) flows through the secondary winding of T1 and through diode D1 to the output filter capacitor COUT and the load. During this time the magnetizing current in T1 is increasing due to the positive voltage placed across its windings. This positive voltage is determined by the output capacitor voltage, VOUT, plus the forward voltage drop of D1. During the second half of the switching cycle, transistor Q2 and diode D2 are on and Q1 and D1 are off. While the current of inductor L flows through transformer T2 in the same manner as described above for T1, the magnetizing current of transformer T1 flows through its tertiary winding and diode D3 to the output filter capacitor, COUT. This arrangement of the tertiary winding provides a means to reset the T1 transformer core with a negative voltage and to recover most of the magnetizing inductance energy. The tertiary winding may alternatively be connected to other suitable points in the power circuit, including those on the primary side of the transformer. Other techniques for resetting the core and/or for recovering the magnetizing energy are known in the art and may be used here. In particular, the tertiary winding could be eliminated and replaced with a conventional clamp circuit attached to either the primary or secondary winding and designed to impose a negative voltage across the transformer during its operative half cycle. Techniques to recover the energy delivered to this clamp circuit, such as the one in which a transistor is placed in anti-parallel with a clamping diode so that energy can flow from the clamping circuitry back into the magnetizing inductance, could also be used. Notice that because the isolation stage of FIG. 2 is fed by an inductor (L), it is important to make sure there is at least one path through which the current in this inductor can flow. At the transitions between each half cycle, it is therefore typical to turn on the new primary side transistor (say Q2) before turning off the old primary side transistor (say Q1). The time when both transistors are on will be referred to as an overlap interval. In a conventional current-fed push-pull topology where all the transformer windings are coupled on a single core, turning on both primary-side transistors will cause the voltage across the transformer windings to drop to zero, the output diodes to turn off, and the power to stop flowing through the isolation stage. Here, however, since two separate, uncoupled transformers are used, the voltage across the transformer windings does not have to collapse to zero when both Q1 and Q2 are on. Instead, both of the output diodes D1 and D2 turn on, both transformers have a voltage across them determined by the output voltage, and the current of inductor L splits (not necessarily equally) between the two halves of the isolation stage. The power flow through the isolation stage is therefore not interrupted (except to charge/discharge parasitic capacitances and inductances). This means the output filter (COUT) can be made much smaller and simpler than would otherwise be necessary. It also means that the isolation stage does not impose a large fundamental frequency voltage ripple across the inductor (L) which provides its current-fed input characteristic. After an appropriate amount of overlap time has elapsed, the old primary side transistor (say Q1) is turned off. The voltage across this transistor rises as its parasitic capacitance is charged by the current that had been flowing through the channel. Once this voltage rises high enough to forward bias diode D3 connected to the tertiary winding, the transistor voltage becomes clamped, although an over-ring and/or a commutation interval will occur due to parasitic leakage inductance. Eventually, all of the current in inductor L will flow through switch Q2, switch Q1 will be off, and the magnetizing current of T1 will flow through diode D3. Now replace output diodes D1 and D2 with MOSFET synchronous rectifiers Q3 and Q4, as shown in FIG. 3. Note that in this and later figures, the body diode of the MOSFET synchronous rectifier is explicitly shown since it plays a role in the circuit's operation. More generally, the schematical drawings of Q3 and Q4 depict the need for a controlled rectifier (e.g. a transistor) and an uncontrolled rectifier (e.g. a diode) connected in parallel. These two devices may be monolithically integrated, as they are for power MOSFETs, or they may be separate components. The positions of these synchronous rectifiers in the circuit are slightly different than the positions of the diodes in FIG. 2. They are still in series with their respective secondary windings, but are connected to the minus output terminal rather than the positive output terminal. This is done to have the sources of both N-channel MOSFETs connected to a single, DC node. If P-channel MOSFETs are to be used, their position in the circuit would be as shown in the partial schematic of FIG. 4. This position permits the P-channel devices to also have their sources connected to a single, DC node. As shown in FIG. 3, the gates of the synchronous rectifier MOSFETs are cross-coupled to the opposite transformers. With this connection, the voltage across one transformer determines the gate voltage, and therefore the conduction state (on or off) of the MOSFET connected to the other transformer, and vice versa. These connections therefore provide properly timed drives to the gates of the MOSFETs without the need for special secondary side control circuitry. For instance, during the half cycle in which transistor Q1 is turned on and transistor Q2 is off, the current of inductor L flows into the primary of T1 and out its secondary. This secondary side current will flow through transistor Q3 (note that even if Q3's channel is not turned on, the secondary side current will flow through the transistor's internal anti-parallel body diode). The voltage across transformer T1's secondary winding is therefore positive, and equal to the output voltage VOUT plus the voltage drop across Q3. The voltage across T2's secondary winding is negative during this time, with a magnitude approximately equal to the output voltage if the magnetizing inductance reset circuitry takes approximately the whole half cycle to finish its reset function. (The negative secondary winding voltage may be made greater than the positive voltage so that the core will finish its reset before the next half cycle begins. This could be accomplished, for example, by using less turns on the tertiary winding.) Referring to FIG. 3, the voltage at node A during this state of operation is nearly zero with respect to the indicated secondary-side ground node (actually the voltage is slightly negative due to the drop across Q3). The voltage at node B, on the other hand, is, following our example, approximately twice the output voltage (say 10 volts for a 5 volt output). Given the way these nodes are connected to the synchronous rectifier transistors, Q3 is turned on and Q4 is turned off. These respective conduction states are consistent with transformer T1 delivering the power and transformer T2 being reset. In the second half-cycle when Q2 is on and Q1 is off, the voltage at node B will be nearly zero (causing Q3 to be off) and the voltage at node A will be approximately twice the output voltage (causing Q4 to be on). During the transition from one half-cycle to the next, the sequence of operation is as follows. Start with Q1 and Q3 on, Q2 and Q4 off. (The clamp circuit's diode D4 may still be on, or it may have stopped conducting at this point if the magnetizing inductance has finished resetting to zero.) First, Q2 is turned on. If we ignore the effects of parasitic capacitances and inductances, the voltage across T2 steps from a negative value to a positive value. The current flowing through inductor L splits between the two primary windings, causing current to flow out of both secondary windings. These secondary currents flow through Q3 and Q4. Since the voltages at both node A and node B are now nearly zero, Q3, which was on, will now be off, and Q4 will remain off (or more precisely, the channels of these two devices are off). The secondary side currents therefore flow through the body diodes of Q3 and Q4. At the end of the overlap interval, Q1 is turned off. The current stops flowing through transformer T1, the body diode of Q3 turns off, and the voltage at node A rises from nearly zero to approximately twice the output voltage as T1 begins its reset half-cycle. With node A voltage high, the channel of transistor Q4 turns on, and the secondary side current of transformer T2 commutates from the body diode of Q4 to its channel. Notice that during the overlap interval, the secondary side currents flow through the body diodes of transistors Q3 and Q4, not their channels. Since these diodes have a high on-state voltage (about 0.9V) compared to the on-state voltage of the channel when the gate-source voltage is high, a much higher power dissipation occurs during this interval. It is therefore desirable to keep the overlap interval short compared to the period of the cycle. Notice also the benefit of using two, uncoupled transformers. The voltage across a first transformer can be changed, causing the channel of the MOSFET synchronous rectifier transistor connected to a second transformer to be turned off, before the voltage across the second transformer is made to change. This could not be done if both primary and both secondary windings were tightly coupled in the same transformer, since the voltages across all the windings would have to change together. FIG. 5 shows the same topology as FIG. 3, but with several important parasitic capacitances and inductances indicated schematically. Each indicated capacitor (C3 and C4) represents the combined effect of one synchronous rectifier's input capacitance and the other rectifier's output capacitance, as well as other parasitic capacitances. Each indicated inductor (LP1, and LP2) represents the combined effect of a transformer leakage inductance and the parasitic inductance associated with the loops formed by the primary side components and the secondary side components. These elements store significant energy that is dissipated each switching cycle in many prior art power circuits where diodes are replaced with synchronous rectifiers. Here, however, the energy stored in these parasitic components is nearly losslessly delivered to and recovered from them. By nearly lossless it is meant that no more than approximately 30% of the energy is dissipated. With one implementation of the present invention, less than 10% dissipation is obtained. The nearly lossless delivery and recovery of energy is achieved because the circuit topology permits the synchronous rectifier switch transitions to proceed as oscillations between inductors and capacitors. These transitions are short compared to the overall on-state and off-state portions of the switching cycle (e.g. less than 20% of the time is taken up by the transition). This characteristic of nearly lossless and relatively short transitions, which we will call soft switching, is distinct from that used in full resonant, quasi-resonant, or multi-resonant converters where the oscillations last for a large portion, if not all, of the on-state and/or off-state time. The way in which the soft-switching characteristic is achieved can be understood in the following manner. Start with transistors Q1 and Q3 on, Q2 and Q4 off. The voltage at node A, and therefore the voltage across C4, is nearly zero and the voltage at node B (and across C3) is approximately twice the output voltage. The current flowing through inductor L, IL, is flowing into the primary winding of T1. The current flowing out of the secondary winding of T1 is IL minus the current flowing in TI's magnetizing inductance, IM, both referenced to the secondary side. The magnetizing current is increasing towards its maximum value, IMPK, which it reaches at the end of the half cycle. When Q2 is turned on at the end of the half cycle, the voltage across both windings of both transformers steps to zero volts in the circuit model depicted in FIG. 5. An L-C oscillatory ring ensues between capacitor C3 and the series combination of the two parasitic inductances, LP1, and LP2. If we assume the parasitic capacitances and inductances are linear, the voltage across C3 decreases cosinusoidally toward zero while the current flowing out of the dotted end of T2's secondary winding, ILP2, builds up sinusoidally toward a peak determined by the initial voltage across C3 divided by the characteristic impedance L P1 + L P2 C 3 . Note that the current flowing out of the dotted end of T1's secondary winding, ILP1, decreases by the same amount that ILP2 increases such that the sum of the two currents is (IL-IMPK), referenced to the secondary side. Also note that during this part of the transition, the voltages across both transformers' secondary windings will be approximately the output voltage minus half the voltage across C3. As the oscillation ensues, therefore, the transformer winding voltages, which started at zero, build up toward the output voltage. The oscillation described above will continue until either the current ILP2 reaches (IL-IMPK) or the voltages across C3 reaches zero. The first scenario occurs for lower values of (IL-IMPK) and the second occurs for higher values of this current. If ILP2 reaches (IL-IMPK) first (and assuming the voltage across C3 has fallen below the threshold voltage of Q3 so that ILP1 is flowing through the body diode of Q3), the oscillation stops because the body diode will not let ILP1 go negative. ILP2 and ILP1 will hold constant at (IL-IMPK) and zero, respectively. Whatever voltage remains across C3 will then discharge linearly due to the current ILP2 until the body diode of Q4 turns on. The body diode will then carry ILP2 until the overlap interval is over and Q1 is turned off. When Q1 is turned off, the magnetizing current IMPK will charge the parallel capacitance of C4 and C1, the parasitic output capacitance of Q1, until the voltage across them is high enough to forward bias the clamping diode D3. At this point the reset portion of T1's cycle commences. Notice that for this first scenario, the complete transition is accomplished with portions of oscillatory rings that, to first order, are lossless. (Some loss does occur due to parasitic series resistance, but this is generally less than 20% of the total energy and typically around 5%.) It could be said that the energy that had been stored in LP1 has been transferred to LP2, and that the energy that had been stored in C3 has been transferred to C4. If, on the other hand, the voltage across C3 reaches zero (or, more precisely, a diode drop negative) first, then the body diode of Q4 will turn on and prevent this voltage from ringing further negative. The currents ILP1 and ILP2 (which are flowing through the body diodes of Q3 and Q4) will hold constant until the overlap interval is over and Q1 is turned off. Once Q1 is turned off, an oscillation ensues between LP1, and C1. This oscillation is driven by the current remaining in LP1, when Q1 was turned off. Given typical parameter values, this oscillation will continue until ILP1 reaches zero, at which point the body diode of Q3 will turn off. Finally, the magnetizing current IMPK charges up the parallel combination of C4 and C1 until the clamping diode D3 turns on to start the reset half-cycle. Notice that for this second scenario, the transition is almost accomplished in a (to first order) lossless manner. Some loss does occur because in the final portion of the transition the voltages across C4 and C1 do not start out equal. C1 has already been partially charged whereas C4 is still at zero volts. As these capacitor voltages equalize, an energy will be lost. This lost energy is a small fraction (typically less than one third) of the energy stored in C1 before the equalization occurs. The energy stored in C1 equals the energy stored in ILP1 when Q1 was turned off, which itself is a small fraction (typically less than one third) of the energy that was stored in this parasitic inductance when it was carrying the full load current, (IL-IM). As such, the energy lost in this second scenario is a very small fraction (typically less than one ninth) of the total energy originally stored in (or delivered to) LP1, LP2, C3 and C4. In other words, most of the parasitic energy is recovered. Note that since the second scenario has a small amount of loss, it may be desirable to avoid this scenario by adjusting component values. One approach would be to make C3 and C4 bigger by augmenting the parasitic capacitors with explicit capacitors placed in parallel. With large enough values it is possible to ensure that the first scenario described above holds true for the full range of load currents expected. The descriptions given above for both scenarios must be modified to account for the nonlinear nature of capacitors C3, C4, and C1, and also to account for the reverse recovery charge of the body diodes of Q3 and Q4. The details of the nonlinear waveforms are too complex to be described here, but the goal of recovering most of the parasitic energy is still achieved. As mentioned previously, it is desirable to keep the overlap period as short as possible to minimize the time that the secondary currents are flowing through the body diodes of Q3 and Q4. It is also desirable to allow the energy recovering transitions just described to reach completion. These two competing desires can be traded off to determine an optimum overlap duration. In general, it is desirable to make sure the new primary switch is turned on before the old one is turned off, and that the portion of the half-cycle during which the uncontrolled rectifiers are conducting should, for efficiency sake, be less than 20%. Note that due to delays in the gate drive circuitry it is possible for the overlap interval to appear negative at some point in the control circuit. The size of the output filter required to achieve a given output voltage ripple is affected by the AC ripple in the current of inductor L. This ripple current is largely caused by the switching action of the preregulation stage. A larger inductance, or a higher order filter for the output of the regulation stage, as shown in FIG. 6 where inductor LB and capacitor CB have been added, will reduce this ripple current. The required size of the output filter is also affected by the AC ripple currents flowing in the magnetizing inductances of the transformers. Making these inductances as large as possible to reduce their ripple currents is therefore desirable. It is also beneficial to connect the tertiary reset windings back to a suitable point on the primary side as shown in FIG. 6A where they are connected to capacitor CB, rather than to connect them to the output filter, as shown in FIG. 3. This alternative connection reduces by a factor of two the ripple current seen by the output filter due to the magnetizing inductance currents, compared to the connection shown in FIG. 3, since these magnetizing currents no longer flow to the output capacitor during their respective reset half cycles. The power converter circuits described so far have all had an isolation stage that is current fed. It is also possible to incorporate the invention with an isolation stage that is voltage fed. By “voltage fed” it is meant that the voltage across the primary side of the isolation stage is held relatively constant over the time frame of the switching cycle. Such a converter circuit is shown in FIG. 6B where two uncoupled transformers are used. The operation of the voltage-fed isolation stage is slightly different than for a current-fed isolation stage. Each primary transistor is still turned on for approximately one half the cycle, but instead of providing a brief overlap period during which both primary transistors, Q1 and Q2, are turned on together, here the primary transistors are both turned off for a brief overlap period. During each half cycle, the current flowing into one primary winding and out its respective secondary winding can be determined as follows. Say transistors Q1 and Q3 have just been turned on to begin a new half cycle. At the completion of their switch transition they will be carrying some initial current (to be discussed in more detail below). There is also a difference between the voltage across capacitor CB and the voltage across capacitor COUT, both reflected to the secondary side. This voltage differential will be called ΔV. It appears across the series circuit composed of the leakage/parasitic inductances and resistances of the primary and secondary windings, T1PRI and T1SEC, the transistors Q1 and Q3, and the capacitors CB and COUT. The current flowing through this series L-R circuit responds to the voltage across it, ΔV, in accordance with the component values, all referenced to the secondary side. Since CB and COUT are charged and discharged throughout the half cycle, ΔV will vary. But if we assume ΔV is relatively constant, then the current flowing through the series L-R circuit will change exponentially with an L/R time constant. If this time constant is long compared to the duration of the half cycle, then the current will have a linearly ramping shape. If the time constant is short, that the current will quickly reach a steady value determined by the resistance. To understand the switch transitions that occur between each half cycle, consider the leakage/parasitic inductances, LP1, and LP2, and the capacitances associated with the controlled rectifiers, C3 and C4, to be modeled in the same way as was shown in FIG. 5. Assume Q2 and Q4 have been on and are carrying a final current level, IF, at the end of the half cycle. Transistor Q1 is then turned on, causing the voltage VCB to be applied across primary winding T1PRI, and its reflected value across secondary winding T1SEC. An oscillation between C4 and LP1, will ensue, with the voltage across C4 starting at approximately twice the output voltage. After approximately one quarter of a cycle of this oscillation, the voltage across C4 will attempt to go negative and be clamped by the body diode of Q3. At this point the current flowing through LP1, will have reached a peak value, IS, determined by approximately twice the output voltage divided by the characteristic impedance, {square root}{square root over (LP1/C4)}. This transition discharges capacitor C4 and builds up the current in LP1, to the value IS in a nearly lossless manner. During the quarter cycle of oscillation the voltage across the gate of transistor Q4 will drop below the threshold value for the device, and the channel of Q4 will turn off. The current that had been flowing through the channel will commutate to the body diode of Q4. At this point current if flowing through both transformers' secondary windings and through the body diodes of Q3 and Q4. Q3 is carrying the current IS and Q4 is carrying the current IF. Now transistor Q2 is turned off and its voltage rises as parasitic capacitors are losslessly charged until the voltage is clamped by the diode in series with the tertiary windings, T2TER. Inductor LP2 now has a negative voltage across it and its current ILP2, will therefore linearly ramp down to zero as its energy is recovered back to CB through the clamping circuit. Once this current reaches zero, the body diode of Q4 will turn off and the current will become negative, but only to the point where it equals the second transform's magnetizing current, IMPK (reflected to the secondary side). This current will linearly charge capacitor C3 nearly losslessly as energy is delivered to the capacitor from the magnetizing inductance of the second transformer (reflected to the secondary side). This current will linearly charge capacitor C3 nearly losslessly as energy is delivered to the capacitor from the mangetizing inductance of the second transformer. As the voltage across C3 rises above the threshold value, transistor Q3 will turn on and the current that had been flowing through the body diode of Q3 will commutate to the channel of Q3. The new half cycle will then proceed as discussed above, with IS being the initial value of current mentioned in that discussion. As with the current-fed isolation stage, the transition between the two half cycles has a period of time when the two body diodes are conducting. This condition is highly dissipative and should be kept short by keeping the overlap period that both primary side transistors, Q1 and Q2, are off short. In all of the power converter circuits described above, it might be desirable to slow down the switch transitions in the isolation stage for many reasons. For instance, slower transitions might reduce the high frequency differential-mode and common-mode ripple components in the output voltage waveform. There are several ways the switch transitions might be slowed down. For instance, in a well known manner a resistor could be placed in series with the gate of the primary side transistor Q1 (or Q2) in FIG. 5 so that its gate voltage would change more slowly. Similarly, a resistor could be placed in series with the gate of a synchronous rectifier Q3 or (Q4). In either case an RC circuit is created by the added resistor, R, and the capacitance, C, associated with the transistor. If this RC product is long compared to the normal length of the oscillatory transitions described above, the switch transitions will be slowed down. If the length of the switch transitions are on the order of {square root}{square root over ((LC))} or longer, where L is the leakage/parasitic inductance (LP1 and/or LP2) that oscillates with the capacitor C4 (or C3), then the nearly lossless transitions described above will not be achieved. The more the switch transitions are slowed down, the more the energy delivered to and/or recovered from the capacitors associated with the controlled rectifiers will be dissipated. As such, there is a tradeoff between the power converter's efficiency and its other attributes, such as output ripple content. This tradeoff might result in slower switch transitions in situations where high efficiency is not required or if better synchronous rectifiers in the future have much smaller capacitances. As discussed above, the synchronous rectifier MOSFETs Q3 and Q4 in the circuit of FIG. 3 are driven with a gate-source voltage equal to approximately twice the output voltage. For a 5 volt output, the 10 volt drive that results is appropriate for common MOSFETs. If the output voltage is such that the gate drive voltage is too large for the ratings of the MOSFET, however, steps must be taken to reduce the drive voltage. For example, if the output voltage is 15 volts, a 30 volt gate drive will result, and it is typically desired that the gate be driven to only 10 volts. Also, some MOSFETs are designed to be driven with only 5 volts, or less, at their gates. FIG. 7 shows one way to reduce the drive voltage while maintaining the energy recovery feature. The voltage waveform at node B (or at node A) is capacitively divided down by the series combination of capacitors Cs and C3 (or by C6 and C4). The values of these capacitors are chosen to provide the division of the AC voltage provided at node B (or node A) as desired. For example, if node B has a 30 volt step change and a 10 volt step change is desired at the gate of Q3, then C5 should have one half the capacitance of C3. Since C3 may be comprised of the parasitic capacitance of Q3, it is likely to be nonlinear. In this case, an effective value of capacitance that relates the large scale change in charge to the large scale change in voltage should be used in the calculation to determine C5. Since a capacitor divider only divides the AC components of a waveform, additional components need to be added to determine the DC component of the voltage applied to the gates of Q3 and Q4. FIG. 7 shows one way to do this in which two resistors, R1 and R2 (or R3 and R4), provide the correct division of the DC component of the voltage at node B (or node A). These resistors should have values large enough to keep their dissipation reasonably small. On the other hand, the resistors should be small enough such that the time constant of the combined capacitor/resistor divider is short enough to respond to transients such as start-up. Other techniques employing diodes or zener diodes that are known in the art could be used instead of the resistor technique shown in FIG. 7. One variation of the invention described herein would be to create a power supply with multiple outputs by having more than one secondary winding on each transformer in the isolation stage. For example, by using two secondary windings with the same number of turns it would be possible to create a positive 12 volt output and a negative 12 volt output. If the two secondary windings have a different number of turns it would be possible to create two output voltages of different magnitudes (e.g., 5 volts and 3.3 volts). Another approach for creating multiple outputs would be to have multiple isolation stages, each with a turns-ratio appropriate for their respective output voltages. When multiple outputs are provided in this manner, a phenomenon commonly called cross-regulation occurs. A single regulation stage cannot control the various output voltages independently, and these output voltages depend not just on the relative turns ratios, but also on the voltage drops that result as the various output currents flow through the impedances of their various output paths. A change in any one or more output currents therefore causes a change in the voltages of those outputs that are not used for feedback to the regulation stage. If this variation due to changes in output currents is a problem, then various approaches for providing regulation of the uncontrolled outputs can be provided. For example, a linear regulator might be added to each output that is not otherwise regulated. One advantageous approach to providing linear regulation with the power circuits described here is to control how much the synchronous rectifier MOSFETs are turned on during their conduction state. This can be done by adding circuitry to limit the peak voltage to which their gates will be driven so that their on-state resistances can be made larger than their minimum values. It can also be done by controlling the portion of operative half cycle during which a MOSFET's gate voltage is allowed to be high so that the MOSFET's body diode conducts for the rest of the time. With both techniques, the amount to which the output voltage can be regulated is the difference between the voltage drop of the synchronous rectifiers when their channels are fully on (i.e., when they are at their minimum resistance) and when only their body diodes are carrying the current. One way to accomplish the first technique, that of controlling the peak gate voltage, is to use the basic capacitor divider circuit that was shown in FIG. 7. All that is needed is to make the resistor divider ratio, (or, alternatively, the diode clamping voltage if such an approach is chosen) dependent on a control signal derived from the error in the output voltage compared to its desired value. The goal is to shift the DC component of the gate voltage in response to the error signal such that the peak voltage applied to the gate, and therefore the on-state resistance and voltage of the synchronous rectifier, helps to minimize this error. Various control circuitry schemes that might be used to achieve this goal will be obvious to one skilled in the art. Note that this approach preserves the energy recovery feature of the gate drive. Note also that if the voltages at nodes A and B are such that no AC division is desired, then C5 and C6 should be made large compared to C3 and C4. FIG. 8 shows an alternative method to control the DC component of the gate voltage waveform. The output voltage (or a scaled version of it) is subtracted from a reference voltage and the error is multipled by the gain of an op-amp circuit. The output of the op-amp (node C) is then connected to the synchronous rectifier gates through resistors that are large enough to not significantly alter the AC waveforms at the gates. With this connection, the DC components of the gate voltages will equal the output voltage of the op-amp at node C. If the gain of the op-amp circuit is large enough, such as when an integrator is used, the error in the output voltage will be driven toward zero. ZF and ZI, are impedances that should be chosen, with well established techniques, to ensure stability of this feedback loop while providing the gain desired. The range of voltage required at the output of the op-amp depends on the particular application, and it may include negative values. This range influences the supply voltage requirements for the op-amp. Also, if the op-amp's output voltage gets too high, the synchronous rectifiers may not turn off when they are supposed to. Some means of limiting this voltage, such as a clamp circuit, may therefore be desirable. One way to accomplish the second technique, that of controlling the portion of the half cycle in which the MOSFET is gated on, is to place a low power switch network between the gate of Q3 (or Q4), node B (or node A), and ground. This network (composed, say, of analog switches operated with digital control signals) might be used to keep the gate voltage grounded for some period of time after the node voltage increases, and to then connect the gate to node B (or A) for the remainder of the half cycle with a switch capable of bidirectional current flow. The length of the delay would be based on a signal derived from the error in the output voltage. With this approach, the energy recovery feature associated with discharging each synchronous rectifier's gate capacitance is preserved, but the charging transition will become lossy. Alternatively, the switch network could be controlled to start out the half cycle with the gate connected to node B (or A), and then after some delay to connect the gate to ground. Using a synchronous rectifier to provide regulation as well as rectification, as described above, is not limited to multiple-output situations. It can also be used in single-output situations either as the total regulation stage or as an additional regulation stage to augment the first one. It is also possible to use DC-DC switching regulators on the secondary side to achieve the additional regulation desired, or to create more than one output voltage from any of the outputs of the isolation stage. With multiple outputs it is not necessary for the gate of each controlled rectifier to be connected to secondary winding of the other transformer which corresponds to the same output. For instance, if the two outputs are 5 volts and 3.3 volts, the gates of the 3.3 volts output controlled rectifiers could be connected to the 5 volt output secondary windings. Doing so would give these controlled rectifiers a 10 volt gate drive, resulting in a lower on-state resistance than if they had a 6.6 volt gate drive. In some situations, it may be desirable to place the isolation stage first in the power flow, and to have the regulation stage follow. For example, when there are many outputs sharing the total power, the circuit might be configured as one isolation/step-down (or step-up) stage followed by several DC-DC switching or linear regulators. No matter where the isolation stage is situated, if it is to be current fed this requirement could be met with active circuitry as well as by a passive component such as an inductor. For instance, if the current fed isolation stage follows a regulation stage that is achieved with a linear regulator, then this linear regulator could be designed to have a large AC output impedance to achieve the input requirement of the current fed isolation stage. When the regulation stage precedes the isolation stage, it is not necessary to sense the isolated output voltage to control the regulation. An alternative approach is to sense the voltage on the primary side of the isolation stage, which may eliminate the need for secondary side circuitry and the need to bridge the feedback control signal across the isolation barrier. For example, in FIG. 6 the voltage across CB, the capacitor of the third-order output filter of the down converter, could be used. This voltage nearly represents the isolated output voltage (corrected for the turns-ratio). It differs only due to the resistive (and parasitic inductance commutation) drops between CB and the output. Since these drops are small and proportional to the current flowing through the isolation stage, the error in output voltage they create can either be tolerated or corrected. To correct the error, the current on the primary side could be sensed, multiplied by an appropriate gain, and the result used to modify the reference voltage to which the voltage across CB is compared. Since these resistive drops vary with temperature, it might also be desirable to include temperature compensation in the control circuitry. Note that this approach could also be used to correct for resistive drops along the leads connecting the supply's output to its load. The embodiments of the invention described above have used two uncoupled transformers for the isolation stage. It is also possible, as shown in FIG. 9, to use a single transformer T in which, for example, there are two primary windings TPRI1, TPRI2 and two secondary windings, TSEC1, TSEC2. While the two primary windings may be tightly coupled, either the two secondaries should be loosely coupled to each other or the connections to the output capacitors and synchronous rectifier transistors should provide adequate parasitic inductance. The resulting leakage and parasitic inductance on the secondary side can then be modeled as is shown in FIG. 9. With this inductance present in the secondary side loops, the operation of the coupled isolation stage during the overlap period is similar to what was described above for the uncoupled case. With Q1 and Q3 on, turn Q2 on. The voltage across the transformer windings, as modeled in FIG. 9, drops to zero, which is consistent with what must happen if the primary windings are tightly coupled. A nearly-lossless energy saving transition involving inductor/capacitor oscillations and linear discharges then ensues. What is different here is that the overlap period during which both Q1 and Q2 are on cannot last too long. If the overlap lasts too long, the transient waveforms will settle into a state where the voltages at nodes A and B rise to the output voltage. If this voltage is higher than the gates' threshold levels, transistors Q3 and Q4 will partially turn on. A large amount of energy will then be dissipated while this state persists, and it is possible for the output capacitor to be significantly discharged. These problems can be avoided by making sure the overlap period when both Q1 and Q2 are on does not last too long. For a given converter, an overlap period can be found which will give the highest converter efficiency. The more leakage/parasitic inductance there is, the longer an overlap period that can be tolerated. Based on the overlap time provided by a given control circuit, it may become necessary to add additional inductance by increasing the leakage or parasitic inductance. With a coupled transformer it is not necessary to provide a separate reset circuit (whether it uses a tertiary winding or not) since the magnetizing current always has a path through which it can flow. With a coupled transformer it is necessary to keep the lengths of the two halves of the cycle well balanced to avoid imposing an average voltage across the core and driving it into saturation. Several techniques for balancing the two half cycles are well known in the art. When two or more power supplies are connected in parallel, diodes are sometimes placed in series with each supply's output to avoid a situation where one supply's failure, seen as a short at its output, takes down the entire output bus. These “ORing” diodes typically dissipate a significant amount of energy. One way to reduce this dissipation is to replace the diode with a MOSFET having a lower on-state voltage. This “ORing” synchronous rectifier MOSFET can be placed in either output lead, with its body diode pointing in the direction of the output current flow. With the invention described here, the voltage for driving the gate of this MOSFET, Q5, can be derived by connecting diodes to node A and/or node B (or to nodes of capacitor dividers connected to these nodes), as shown in FIG. 10. These diodes rectify the switching waveforms at node A and/or node B to give a constant voltage suitable for turning on the ORing MOSFET at node D. A filter capacitor, CF, might be added to the circuit as shown in the figure, or the parasitic input capacitance of the ORing MOSFET might be used alone. A resistor RF ensures the gate voltage discharges when the drive is removed. If the power supply fails in a way that creates a short at its output, such as when a synchronous rectifier shorts, the voltages at nodes A and B will also be shorted after the transient is complete. With its gate drive no longer supplied, the ORing MOSFET will turn off, and the failed supply will be disconnected from the output bus. When two (or more) power supplies of the type described here are placed in parallel, a problem can arise. If one power supply is turned on while another is left off (i.e. not switching), the output bus voltage generated by the first supply will appear at the gates of the second supply's synchronous rectifiers. Once this voltage rises above the threshold value, these synchronous rectifiers will turn on and draw current. At the least this will result in extra dissipation, but it could result in a shorted output bus. This problem can occur even if both supplies are turned on and off together if one supply's transition “gets ahead” of the other. There are several approaches to solving this problem. One is to make sure both supplies have matched transitions. Another is to connect the supplies together with ORing diodes so that no supply can draw current from the combined output bus. If an ORing MOSFET is used instead of an ORing diode, however, this second approach can still fail to solve the problem. For instance, consider the case where a supply drives its ORing MOSFET with the technique shown in FIG. 10. Assume the bus voltage is already high due to another supply, and the first supply is then turned on in a way that causes its output voltage to rise slowly toward its desired value. If the ORing MOSFET's gate voltage rises high enough to turn it on before the newly rising output voltage approximately matches the existing bus voltage, then there will be at least a momentary large current flow as the two voltages equalize. To avoid this problem additional circuitry can be added to make sure an ORing MOSFET is not turned on until its supply's output voltage has approximately reached the bus voltage. This might be done by sensing the two voltages and taking appropriate action, or it might be done by providing a delay between when the ORing MOSFET's gate drive is made available and when it is actually applied to the gate. Such a delay should only affect the turn-on, however; the turn-off of the ORing MOSFET should have minimal delay so that the protective function of the transistor can be provided. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims. For instance, the regulation stage could be composed of an up-converter. The ideas that have been presented in terms of the N-channel implementation of the synchronous rectifier MOSFET can be modified to apply to the P-channel implementation, as well. The components shown in the schematics of the figures (such as Q3 in FIG. 3) could be implemented with several discrete parts connected in parallel. In addition, certain aspects of the invention could be applied to a power converter having only one primary transformer winding and/or one secondary transformer winding. | <SOH> BACKGROUND OF THE INVENTION <EOH>This invention pertains to switching power converters. A specific example of a power converter is a DC-DC power supply that draws 100 watts of power from a 48 volt DC source and converts it to a 5 volt DC output to drive logic circuitry. The nominal values and ranges of the input and output voltages, as well as the maximum power handling capability of the converter, depend on the application. It is common today for switching power supplies to have a switching frequency of 100 kHz or higher. Such a high switching frequency permits the capacitors, inductors, and transformers in the converter to be physically small. The reduction in the overall volume of the converter that results is desirable to the users of such supplies. Another important attribute of a power supply is its efficiency. The higher the efficiency, the less heat that is dissipated within the supply, and the less design effort, volume, weight, and cost that must be devoted to remove this heat. A higher efficiency is therefore also desirable to the users of these supplies. A significant fraction of the energy dissipated in a power supply is due to the on-state (or conduction) loss of the diodes used, particularly if the load and/or source voltages are low (e.g. 3.3, 5, or 12 volts). In order to reduce this conduction loss, the diodes are sometimes replaced with transistors whose on-state voltages are much smaller. These transistors, called synchronous rectifiers, are typically power MOSFETs for converters switching in the 100 kHz and higher range. The use of transistors as synchronous rectifiers in high switching frequency converters presents several technical challenges. One is the need to provide properly timed drives to the control terminals of these transistors. This task is made more complicated when the converter provides electrical isolation between its input and output because the synchronous rectifier drives are then isolated from the drives of the main, primary side transistors. Another challenge is the need to minimize losses during the switch transitions of the synchronous rectifiers. An important portion of these switching losses is due to the need to charge and discharge the parasitic capacitances of the transistors, the parasitic inductances of interconnections, and the leakage inductance of transformer windings. | <SOH> SUMMARY OF THE INVENTION <EOH>Various approaches to addressing these technical challenges have been presented in the prior art, but further improvements are needed. In response to this need, a new power circuit topology designed to work with synchronous rectifiers in a manner that better addresses the challenges is presented here. In preferred embodiments of the invention, a power converter comprises a power source and a primary transformer winding circuit having at least one primary winding connected to the source. A secondary transformer winding circuit has at least one secondary winding coupled to the at least one primary winding. Plural controlled rectifiers, such as voltage controlled field effect transistors, each having a parallel uncontrolled rectifier, are connected to a secondary winding. Each controlled rectifier is turned on and off in synchronization with the voltage waveform across a primary winding to provide an output. Each primary winding has a voltage waveform with a fixed duty cycle and transition times which are short relative to the on-state and off-state times of the controlled rectifiers. A regulator regulates the output while the fixed duty cycle is maintained. In the preferred embodiments, first and second primary transformer windings are connected to the source and first and second primary switches are connected in series with the first and second primary windings, respectively. First and second secondary transformer windings are coupled to the first and second primary windings, respectively. First and second controlled rectifiers, each having a parallel uncontrolled rectifier, are in series with the first and second secondary windings, respectively. A controller turns on the first and second primary switches in opposition, each for approximately one half of the switching cycle with transition times which are short relative to the on-state and off-state times of the first and second controlled rectifiers. The first and second controlled rectifiers are controlled to be on at substantially the same times that the first and second primary switches, respectively, are on. In a system embodying the invention, energy may be nearly losslessly delivered to and recovered from capacitors associated with the controlled rectifiers during their transition times. In the preferred embodiments, the first primary and secondary transformer windings and the second primary and secondary transformer windings are on separate uncoupled transformers, but the two primary windings and two secondary windings may be coupled on a single transformer. Preferably, each controlled rectifier is turned on and off by a signal applied to a control terminal relative to a reference terminal of the controlled rectifier, and the reference terminals of the controlled rectifiers are connected to a common node. Further, the signal that controls each controlled rectifier is derived from the voltage at the connection between the other controlled rectifier and its associated secondary winding. Regulation may be through a separate regulation stage which in one form is on the primary side of the converter as part of the power source. Power conversion may then be regulated in response to a variable sensed on the primary side of the converter. Alternatively, the regulator may be a regulation stage on the secondary side of the converter, and power conversion may be regulated by control of the controlled rectifiers. Specifically, the on-state voltage of a controlled rectifier may be made larger than its minimum value to provide regulation, or the on-state duration of a controlled rectifier may be shorter than its maximum value to provide regulation. The preferred systems include reset circuits associated with transformers for flow of magnetizing current. The energy stored in the magnetizing inductance may be recovered. In one form, the reset circuit comprises a tertiary transformer winding, and in another form it comprises a clamp. In preferred embodiments, the power source has a current fed output, the current fed output characteristic of the power source being provided by an inductor. Alternatively, the power source may have a voltage-fed output where the voltage-fed output characteristic of the power source is provided by a capacitor. In either case, the characteristics may alternatively be provided by active circuitry. With the preferred current-fed output, the primary switches are both turned on during overlapping periods, and the overlapping periods may be selected to achieve maximum efficiency. With the voltage-fed output, the primary switches are both turned off during overlapping periods. Additional leakage or parasitic inductance may be added to the circuit to accommodate an overlap period. In one embodiment, a signal controlling a controlled rectifier is derived with a capacitive divider circuit. A circuit may determine the DC component of the signal controlling the controlled rectifier, and the DC component of the signal may be adjusted to provide regulation. In accordance with another aspect of the invention, an ORing controlled rectifier connects the converter's output to an output bus to which multiple converter outputs are coupled, and the ORing controlled rectifier is turned off if the power converter fails. Preferably, the signal controlling the ORing controlled rectifier is derived from one or more secondary windings. The ORing controlled rectifier is turned on when the converter's output voltage approximately matches the bus voltage. | 20040329 | 20060704 | 20050203 | 64530.0 | 8 | NGUYEN, MATTHEW VAN | HIGH EFFICIENCY POWER CONVERTER | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,812,321 | ACCEPTED | Layer-3 network routing with RPR layer-2 visibility | Routing tables of OSI layer-3 network elements are modified in order to enable entry to a RPR subnet at different entry points. This enables virtual tunnels or routing paths to utilize all existing entry links to the RPR subnet and to minimize cost factors, such as the number of RPR spans required to traverse the RPR subnet from the entry point to a destination RPR node. The routing tables of RPR subnet elements are modified, such that traffic leaving different elements but destined for the same network location outside the RPR subnet may have individualized RPR exit nodes. The respective RPR exit points for the network elements are chosen to minimize cost factors, such as the number of RPR spans required to reach the exit node from each RPR node. | 1. A method for obtaining ingress to a layer-2 ring network to reach nodes thereof, said nodes including ingress nodes that couple said ring network to an external layer-3 network, the method comprising the steps of: in said ingress nodes, creating entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric determined responsively to a topology of said ring network; thereafter uploading said host table to external elements of said layer-3 network; defining paths from said external elements to designated ones of said nodes of said ring network, by selecting one of said ingress nodes for each of said paths responsively to said metric; and transmitting data from network elements that are external to said ring network to at least one of said nodes via a selected one of said paths. 2. The method according to claim 1, wherein said ring network is a RPR subnet. 3. The method according to claim 1, wherein said ingress nodes are selected responsively to a minimum value of said metric. 4. The method according to claim 1, wherein said ingress nodes are selected responsively to a maximum value of said metric. 5. The method according to claim 1, wherein said step of defining paths is performed in each of one or more of said external elements. 6. The method according to claim 1, wherein said step of defining paths comprises dynamically defining virtual tunnels. 7. The method according to claim 1, wherein said layer-3 network is an IP network, and wherein said step of uploading comprises flooding router LSA's with a mask. 8. The method according to claim 7, wherein said step of flooding comprises flooding stub networks. 9. The method according to claim 7, wherein said mask is a 32-bit mask. 10. The method according to claim 1, wherein said step of uploading comprises external LSA advertising to said layer-3 network. 11. The method according to claim 1, wherein said metric comprises a cost factor that is computed between one of said ingress nodes and said respective one of said nodes. 12. The method according to claim 11, wherein said cost factor varies with a number of layer-2 spans between said one ingress node and said respective one of said nodes. 13. The method according to claim 11, wherein said step of defining paths comprises computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 14. The method according to claim 1, wherein said metric is determined responsively to a number of hops between said ingress nodes and said respective one of said nodes. 15. The method according to claim 14, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 16. The method according to claim 14, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 17. A computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, comprising the steps of: configuring ingress nodes of said ring network to create entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric; configuring said ingress nodes to thereafter upload said host table to external elements of a data network that interfaces with said ring network via said ingress nodes; configuring said external elements to define paths from said external elements to designated ones of said nodes of said ring network, each of said paths leading through a selected one of said ingress nodes responsively to said metric; and transmitting data from network elements that are external to said ring network to at least one of said nodes via a selected one of said paths. 18. The computer software product according to claim 17, wherein said ring network is a RPR subnet. 19. The computer software product according to claim 17, wherein said ingress nodes are selected responsively to a minimum value of said metric. 20. The computer software product according to claim 17, wherein said ingress nodes are selected responsively to a maximum value of said metric. 21. The computer software product according to claim 17, wherein said paths are virtual tunnels. 22. The computer software product according to claim 17, wherein said ingress nodes are adapted to upload said host table by flooding router LSA's with a mask. 23. The computer software product according to claim 22, wherein flooding comprises flooding stub networks. 24. The computer software product according to claim 22, wherein said mask is a 32-bit mask. 25. The computer software product according to claim 17, wherein said ingress nodes are adapted to upload said host table by external LSA advertising to said data network. 26. The computer software product according to claim 17, wherein said metric comprises a cost factor that is computed between one of said ingress nodes and said respective one of said nodes. 27. The computer software product according to claim 26, wherein said cost factor varies with a number of layer-2 spans between said one ingress node and said respective one of said nodes. 28. The computer software product according to claim 26, wherein said paths are defined by computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 29. The computer software product according to claim 17, wherein said metric comprises a number of hops between said ingress nodes and said respective one of said nodes. 30. The computer software product according to claim 29, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 31. The computer software product according to claim 29, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 32. A network routing system for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, comprising: first routers disposed in ingress nodes of said ring network, said first routers being adapted for creating entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric; said first routers being further adapted for uploading said host table to external elements of a data network that interfaces with said ring network via said ingress nodes; a second router disposed in at least one of said external elements, said second router being adapted for defining paths from said external elements to designated ones of said nodes of said ring network, each of said paths leading through a selected one of said ingress nodes responsively to said metric; and transmitting data from network elements that are external to said ring network to at least one of said nodes via a selected one of said paths. 33. The network routing system according to claim 32, wherein said ring network is a RPR subnet. 34. The network routing system according to claim 32, wherein said ingress nodes are selected responsively to a minimum value of said metric. 35. The network routing system according to claim 32, wherein said ingress nodes are selected responsively to a maximum value of said metric. 36. The network routing system according to claim 32, wherein said paths are virtual tunnels. 37. The network routing system according to claim 32, wherein said first routers perform uploading by flooding router LSA's with a mask. 38. The network routing system according to claim 37, wherein said step of flooding comprises flooding stub networks. 39. The network routing system according to claim 37, wherein said mask is a 32-bit mask. 40. The network routing system according to claim 32, wherein said first routers perform uploading by external LSA advertising to said data network. 41. The network routing system according to claim 32, wherein said metric comprises a cost factor that is computed between one of said ingress nodes and said respective one of said nodes. 42. The network routing system according to claim 41, wherein said cost factor varies with a number of layer-2 spans between said one ingress node and said respective one of said nodes. 43. The network routing system according to claim 41, wherein said paths are defined by computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 44. The network routing system according to claim 32, wherein said metric comprises a number of hops between said ingress nodes and said respective one of said nodes. 45. The network routing system according to claim 44, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 46. The network routing system according to claim 44, wherein said ingress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 47. A method for obtaining egress from a layer-2 ring network to an external layer-3 network, comprising the steps of: in nodes of said ring network creating entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric determined responsively to a topology of the ring network; defining paths from said nodes through egress nodes of said ring network to external elements in said external layer-3 network; selecting one of said paths responsively to said metric; and transmitting data from at least one of said nodes via said selected one of said paths to network elements that are external to said ring network. 48. The method according to claim 47, wherein said ring network is a RPR subnet. 49. The method according to claim 47, wherein said egress nodes are selected responsively to a minimum value of said metric. 50. The method according to claim 47, wherein said egress nodes are selected responsively to a maximum value of said metric. 51. The method according to claim 47, wherein said step of defining paths comprises dynamically defining virtual tunnels. 52. The method according to claim 47, further comprising the step of memorizing said paths in said host table of said nodes. 53. The method according to claim 47, wherein said metric comprises a cost factor that is computed between one of said egress nodes with said ring network and said respective one of said nodes. 54. The method according to claim 53, wherein said cost factor varies with a number of layer-2 spans between said one egress node and said respective one of said nodes. 55. The method according to claim 53, wherein said paths are defined by computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 56. The method according to claim 47, wherein said metric comprises a number of hops between said egress nodes and said respective one of said nodes. 57. The method according to claim 56, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 58. The method according to claim 56, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 59. A computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining egress from a layer-2 ring network to an external layer-3 network comprising the steps of: in nodes of said ring network creating entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric; defining paths from said nodes through egress nodes of said ring network; selecting one of said paths responsively to said metric; and transmitting data from said nodes via said selected paths to network elements that are external to said ring network. 60. The computer software product according to claim 59, wherein said ring network is a RPR subnet. 61. The computer software product according to claim 59, wherein said egress nodes are selected responsively to a minimum value of said metric. 62. The computer software product according to claim 59, wherein said egress nodes are selected responsively to a maximum value of said metric. 63. The computer software product according to claim 59, wherein said step of defining paths comprises dynamically defining virtual tunnels. 64. The computer software product according to claim 59, further comprising the step of memorizing said paths in said host table of said nodes. 65. The computer software product according to claim 59, wherein said metric comprises a cost factor that is computed between one of said egress nodes with said ring network and said respective one of said nodes. 66. The computer software product according to claim 65, wherein said cost factor varies with a number of layer-2 spans between said one egress node and said respective one of said nodes. 67. The computer software product according to claim 65, wherein said paths are defined by computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 68. The computer software product according to claim 59, wherein said metric comprises a number of hops between said egress nodes and said respective one of said nodes. 69. The computer software product according to claim 68, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 70. The computer software product according to claim 68, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 71. A network routing system for obtaining egress from a layer-2 ring network to an external layer-3 network comprising: a plurality of routers disposed in nodes of said ring network, said routers being adapted for creating entries in a host table, each of said entries comprising an address of a respective one of said nodes of said ring network and a metric, said routers being further adapted for defining paths from said nodes through egress nodes of said ring network, for selecting one of said paths responsively to said metric; and for transmitting data from said nodes via said selected paths to network elements that are external to said ring network. 72. The network routing system according to claim 71, wherein said ring network is a RPR subnet. 73. The network routing system according to claim 71, wherein said egress nodes are selected responsively to a minimum value of said metric. 74. The network routing system according to claim 71, wherein said egress nodes are selected responsively to a maximum value of said metric. 75. The network routing system according to claim 71, wherein said paths are dynamic virtual tunnels. 76. The network routing system according to claim 71, wherein said paths are stored in said host table. 77. The network routing system according to claim 71, wherein said metric comprises a cost factor that is computed between one of said egress nodes with said ring network and said respective one of said nodes. 78. The network routing system according to claim 77, wherein said cost factor varies with a number of layer-2 spans between said one egress node and said respective one of said nodes. 79. The network routing system according to claim 77, wherein said paths are defined by computing a total cost based on said cost factor and on interface costs that are assigned in said layer-3 network, and selecting said paths so as to minimize said total cost. 80. The network routing system according to claim 71, wherein said metric comprises a number of hops between said egress nodes and said respective one of said nodes. 81. The network routing system according to claim 80, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined proportionally to said interface cost and to said number of hops. 82. The network routing system according to claim 80, wherein said egress nodes are configured with an interface cost on said layer-3 network, and wherein said metric is determined by said interface cost divided by said number of hops. 83. A method for routing data through a layer-2 ring network, said ring network having interface nodes with external network elements of a data network and non-interface nodes, comprising the steps of: in said interface nodes of said ring network creating first entries in a first host table, each of said first entries comprising an address of a respective one of said non-interface nodes and a first metric; thereafter uploading said first host table to said external network elements; and using said first host table identifying optimum ingress paths from said external network elements to said non-interface nodes, each of said ingress paths leading through one of said interface nodes responsively to said first metric; in said non-interface nodes of said ring network creating second entries in a second host table, each of said second entries comprising an address of a respective one of said interface nodes and a second metric; using said second host table identifying optimum egress paths from said non-interface nodes through different ones of said interface nodes of said ring network, responsively to said second metric; and transmitting data to and from said ring network via said ingress paths and said egress paths. 84. The method according to claim 83, wherein said ring network is a RPR subnet. | BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to communications networks. More particularly, this invention relates to methods and systems for improved utilization of communications networks configured as layer-2 ring networks. 2. Description of the Related Art The meanings of acronyms and certain terminology used herein are given in Table 1. TABLE 1 AS Autonomous System ATM Asynchronous Transfer Mode. A network technology based on transferring data in cells or packets of a fixed size. FEC Forwarding equivalence class HDLC High-level Data Link Control IETF Internet engineering task force IGP Interior Gateway Protocol IP Internet protocol LAN Local Area Network LDP Label distribution protocol LLC Logical link congtrol LSA Link state advertisement LSP Label-switched path LSR Label-switching router MAC Media access control MPLS Multi-protocol label switching MPLS-TE MPLS traffic engineering OSI Open System Interconnection. A networking framework for implementing protocols. OSPF Open Shortest path First. A routing protocol OSPF-TE OSPF enhancements used in traffic engineering RFC Request for comments RIP Routing information protocol RPR Resilient packet rings - a protocol RSVP Resource reservation protocol RSVP-TE An extension of RSVP, used in traffic engineering SRP Spatial reuse protocol TE Traffic engineering TLV Type-Length-Value. An encoding scheme Local Area Networks (LAN's) connect computing systems together. LAN's of all types can be connected together using Media Access Control (MAC) bridges, as set forth in the “IEEE Standard for Information Technology, Telecommunications and Information Exchange between Systems, Local and Metropolitan Area Networks, Common Specifications, Part 3: Media Access Control (MAC) Bridges,” published as ANSI/IEEE Standard 802.1D (1998). The 802.1D standard is available via the Internet at the URL standards.ieee.org/catalog/IEEE802.1.html. Data networks, including LAN's, are commonly conceptualized as a hierarchy of layers according to the Open System Interconnection Model (OSI). OSI defines a networking framework for implementing protocols in seven layers, of which layer-3 (network layer), and layer-2 (data link layer) are relevant to the instant invention. Implementation of layer-3 requires high level knowledge of the network organization, and access to router tables that indicate where to forward or send data. This layer provides high level switching and routing technologies, and creates logical paths, known as virtual circuits, for transmitting data from node to node. In layer-3, data is transmitted by creating a frame that usually contains source and destination network addresses. Layer-2 encapsulates the layer-3 frame, adding more detailed data link control information to form a new, larger frame. Layer-2 implements a transmission protocol and handles flow control, frame synchronization, and handles errors arising in the physical layer (layer-1). Layer-2 is divided into two sublayers: a media access control (MAC) sublayer and a logical link control (LLC) sublayer. The MAC sublayer controls how a computer on the network gains access to the data and its permission to transmit the data. The LLC layer controls frame synchronization, flow control and error checking. HDLC (High-level Data Link Control) is a related term that refers to a group of layer-2 protocols or rules for transmitting data between network points, known as nodes. In HDLC, data is organized into frames and sent across a network to a destination that verifies its successful arrival. The HDLC protocol also manages the flow or pacing at which data is sent. The Open Shortest Path First (OSPF) protocol is a link-state layer-3 routing protocol used for Internet routing. OSPF is described in detail by Moy in OSPF Version 2, published as Request for Comments (RFC) 2328 of the Internet Engineering Task Force (IETF) Network Working Group (April, 1998), which is incorporated herein by reference. This document is available at www.ietf.org, as are the other IETF RFC and draft documents mentioned below. OSPF is used by a group of Internet Protocol (IP) routers in an Autonomous System (AS) to exchange information regarding the system topology. The term “Autonomous System” denotes a group of routers exchanging routing information via a common routing protocol. Each OSPF router maintains an identical topology database, with exceptions as noted below. Based on this database, the routers calculate their routing tables by constructing a shortest-path tree to each of the other routers. Each individual piece of the topology database maintained by the OSPF routers describes the “local state” of a particular router in the Autonomous System. This local state includes information such as the router's usable interfaces and reachable neighbors. The routers distribute their local state information by transmitting a link state advertisement (LSA). Packets containing link state advertisements are flooded throughout the routing domain. The other routers receive these packets and use the LSA information to build and update their databases. OSPF allows collections of contiguous networks and hosts to be grouped together to form an OSPF area. An OSPF area includes routers having interfaces to any one of the grouped networks. Each area runs a separate copy of the basic link-state routing algorithm. The topology of an OSPF area is invisible from outside of the area. Conversely, routers internal to a given area does not know the detailed topology external to the area. This isolation of knowledge results in a marked reduction in routing traffic, as compared to treating the entire Autonomous System as a single link-state domain. A router in an Autonomous System has a separate topological database for each area to which it is connected. Routers connected to multiple areas are called area border routers. However, routers belonging to the same area have, for that area, identical area topological databases. An OSPF LSA database allows a layer-3 aware network element, such as a router, to build its routing table by running the well-known SPF algorithm. The element then routes IP packets based on the actual routing table and on the destination IP address in the IP packet header. A cost is associated with the output side of each router interface, and is used by the router in choosing the least costly path for the packets. This cost is configurable by the system administrator. The lower the cost, the more likely the interface is to be used to forward data traffic. For the purposes of cost calculation and routing, OSPF recognizes two types of networks (which may be organized as IP networks, subnets or supernets): point-to-point networks, which connect a single pair of routers; and multi-access networks, supporting two or more attached routers. Each pair of routers on a multi-access network is assumed to be able to intercommunicate directly. An Ethernet is an example of a multi-access network. Each multi-access network includes a “designated router,” which is responsible for flooding LSA's over the network, as well as certain other protocol functions. Further details concerning network cost calculation and routing are disclosed in application Ser. No. 10/211,066, (Publication No. 20030103449), which is commonly assigned herewith, and herein incorporated by reference. Multi-access layer-2 networks may be configured internally as rings. The leading bi-directional protocol for layer-2 high-speed packet rings is the Resilient Packet Rings (RPR) protocol, which is in the process of being defined as IEEE standard 802.17. Network-layer-routing over RPR is described, for example, by Jogalekar et al., in IP over Resilient Packet Rings (Internet Draft draft-jogalekar-iporpr-00), and by Herrera et al., in A Framework for IP over Packet Transport Rings (Internet Draft draft-ietf-ipoptr-framework-00). A proposed solution for media access control (MAC protocol layer-2) in bi-directional ring networks is the Spatial Reuse Protocol (SRP), which is described by Tsiang et al., in the IETF document RFC-2892, entitled The Cisco SRP MAC Layer Protocol. Using protocols such as these, each node in a ring network can communicate directly with all other nodes through either an inner or an outer ring, using the appropriate Media Access Control (MAC) addresses of the nodes. The terms “inner” and “outer” are used arbitrarily herein to distinguish the different ring traffic directions. These terms have no physical meaning with respect to the actual configuration of the network. Multiprotocol Label Switching (MPLS) is gaining popularity as a method for efficient transportation of data packets over connectionless networks, such as Internet Protocol (IP) networks. MPLS is described in detail by Rosen et al., in Request for Comments (RFC) 3031 of the Internet Engineering Task Force (IETF), entitled “Multiprotocol Label Switching Architecture” (January, 2001). In conventional IP routing, each router along the path of a packet sent through the network analyzes the packet header and independently chooses the next hop for the packet by running a routing algorithm. In MPLS, however, each packet is assigned to a Forwarding Equivalence Class (FEC) when it enters the network, depending on its destination address. The packet receives a short, fixed-length label identifying the FEC to which it belongs. All packets in a given FEC are passed through the network over the same path by label-switching routers (LSR's). Unlike IP routers, LSR's simply use the packet label as an index to a look-up table, which specifies the next hop on the path for each FEC and the label that the LSR should attach to the packet for the next hop. Since the flow of packets along a label-switched path (LSP) under MPLS is completely specified by the label applied at the ingress node of the path, a LSP can be treated as a tunnel through the network. Such tunnels are particularly useful in network traffic engineering, as well as communication security. MPLS tunnels are established by “binding” a particular label, which is assigned at the ingress node to the network, to a particular FEC. Currently, layer-3 routing protocols, such as RIP and OSPF, are unaware of the topology of layer-2 RPR networks with which they must interact. A routing table allows the router to forward packets from source to destination via the most suitable path, i.e., lowest cost, minimum number of hops. The routing table is updated via the routing protocol, which dynamically discovers currently available paths. The routing table may also be updated via static routes, or can be built using a local interface configuration, which is updated by the network administrator. However, the RPR ingress and egress nodes chosen in the operation of automatic routing protocols do not take into account the internal links within the RPR ring, and may therefore cause load imbalances within the RPR subnet, which generally results in suboptimum performance of the larger network. SUMMARY OF THE INVENTION According to a disclosed embodiment of the invention, methods and systems are provided for the manipulation of layer-3 network nodes, external routers, routing tables and elements of layer-2 ring networks, such as RPR networks, enabling the layer-3 elements to view the topology of a layer-2 ring subnet. This feature permits routers to choose optimal entry points to the layer-2 subnet for different routes that pass into or through the layer-2 subnet. This enables virtual tunnels or routing paths to utilize all existing entry links to the subnet and to minimize cost factors, such as the number of spans required to traverse the subnet from the entry point to a destination node of the subnet. In an aspect of the invention, the routing tables of RPR subnet elements are manipulated such that traffic routes originating in or passing through different elements of the RPR subnet and destined for network locations outside the RPR ring have individualized exit nodes. The exit points for the different routes are chosen to minimize cost factors, such as the number of spans required to reach the exit node from each node of the layer-2 subnet. The invention provides a method for obtaining ingress to a layer-2 ring network to reach nodes thereof, the nodes including ingress nodes that couple the ring network to an external layer-3 network, which is carried out in the ingress nodes by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric that is determined responsively to a topology of the ring network. Thereafter, the method is further carried out by uploading the host table to external elements of the layer-3 network, defining paths from the external elements to designated ones of the nodes of the ring network by selecting one of the ingress nodes for each of the paths responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. According to an aspect of the method, the ring network is a RPR subnet. According to an additional aspect of the method, the ingress nodes are selected responsively to a minimum value of the metric. According to another aspect of the method, the ingress nodes are selected responsively to a maximum value of the metric. In an additional aspect of the method, paths are defined in one or more of the external elements. The paths may be virtual tunnels. In one aspect of the method, the layer-3 network is an IP network, and uploading is achieved by flooding router LSA's with a mask, which can be a 32-bit mask. In another aspect of the method stub networks are flooded to achieve uploading. One aspect of the method uploading is performed by external LSA advertising to the layer-3 network. According to another aspect of the method, the metric includes a cost factor that is computed between one of the ingress nodes and the respective one of the nodes. According to yet another aspect of the method, the cost factor varies with a number of layer-2 spans between the one ingress node and the respective one of the nodes. In another aspect of the method paths are defined by computing a total cost based on the cost factor and on interface costs that are assigned in the layer-3 network, and selecting the paths so as to minimize the total cost. According to a further aspect of the method, the metric is determined responsively to a number of hops between the ingress nodes and the respective one of the nodes. According to another aspect of the method, the ingress nodes are configured with an interface cost on the layer-3 network, and the metric is determined proportionally to the interface cost and to the number of hops. According to a further aspect of the method, the ingress nodes are configured with an interface cost on the layer-3 network, and the metric is determined by the interface cost divided by the number of hops. The invention provides a computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, which is carried out by configuring ingress nodes of the ring network to create entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The method is further carried out by configuring the ingress nodes to thereafter upload the host table to external elements of a data network that interfaces with the ring network via the ingress nodes, configuring the external elements to define paths from the external elements to designated ones of the nodes of the ring network, each of the paths leading through a selected one of the ingress nodes responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. The invention provides a network routing system for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, including first routers disposed in ingress nodes of the ring network. The first routers are adapted for creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The first routers are further adapted for uploading the host table to external elements of a data network that interfaces with the ring network via the ingress nodes. A second router is disposed in at least one of the external elements. The second router is adapted for defining paths from the external elements to designated ones of the nodes of the ring network, each of the paths leading through a selected one of the ingress nodes responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. The invention provides a method for obtaining egress from a layer-2 ring network to an external layer-3 network, which is carried out in nodes of the ring network by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network, and a metric determined responsively to a topology of the ring network. The method is further carried out by defining paths from the nodes through egress nodes of the ring network to external elements in the external layer-3 network, selecting one of the paths responsively to the metric, and transmitting data from at least one of the nodes via the selected one of the paths to network elements that are external to the ring network. The invention provides a computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining egress from a layer-2 ring network to an external layer-3 network, which is carried out in nodes of the ring network by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The method is further carried out by defining paths from the nodes through egress nodes of the ring network, selecting one of the paths responsively to the metric, and transmitting data from the nodes via the selected paths to network elements that are external to the ring network. The invention provides a network routing system for obtaining egress from a layer-2 ring network to an external layer-3 network, including a plurality of routers disposed in nodes of the ring network. The routers are adapted for creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The routers are further adapted for defining paths from the nodes through egress nodes of the ring network, for selecting one of the paths responsively to the metric, and for transmitting data from the nodes via the selected paths to network elements that are external to the ring network. The invention provides a method for routing data through a layer-2 ring network, the ring network having interface nodes with external network elements of a data network and non-interface nodes, which is carried out in the interface nodes of the ring network by creating first entries in a first host table, each of the first entries including an address of a respective one of the non-interface nodes and a first metric. The method is further carried out by thereafter uploading the first host table to the external network elements, and using the first host table to identify optimum ingress paths from the external network elements to the non-interface nodes, each of the ingress paths leading through one of the interface nodes responsively to the first metric. The method is further carried out in the non-interface nodes of the ring network by creating second entries in a second host table, each of the second entries including an address of a respective one of the interface nodes and a second metric, using the second host table to identify optimum egress paths from the non-interface nodes through different ones of the interface nodes of the ring network responsively to the second metric, and transmitting data to and from the ring network via the ingress paths and the egress paths. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, reference is made to the detailed description of the invention, by way of example, which is to be read in conjunction with the following drawings, wherein like elements are given like reference numerals, and wherein: FIG. 1 is a schematic diagram illustrating a portion of a data network, which is operative in accordance with a disclosed embodiment of the invention; FIG. 2 is a flow diagram illustrating a method of obtaining ingress to a layer-2 subnet from a layer-3 network at different entry points in accordance with a disclosed embodiment of the invention; and FIG. 3 is a flow diagram illustrating a method of obtaining egress from a layer-2 subnet into a layer-3 network at different exit points in accordance with a disclosed embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent to one skilled in the art, however, that the present invention may be practiced without these specific details. In other instances well-known circuits, control logic, and the details of computer program instructions for conventional algorithms and processes have not been shown in detail in order not to unnecessarily obscure the present invention. Software programming code, which embodies aspects of the present invention, is typically maintained in permanent storage, such as a computer readable medium. In a client-server environment, such software programming code may be stored on a client or a server. The software programming code may be embodied on any of a variety of known media for use with a data processing system. This includes, but is not limited to, magnetic and optical storage devices such as disk drives, magnetic tape, compact discs (CD's), digital video discs (DVD's), and computer instruction signals embodied in a transmission medium with or without a carrier wave upon which the signals are modulated. For example, the transmission medium may include a communications network, such as the Internet. In addition, while the invention may be embodied in computer software, the functions necessary to implement the invention may alternatively be embodied in part or in whole using hardware components such as application-specific integrated circuits or other hardware, or some combination of hardware components and software. Overview. Turning now to the drawings, reference is initially made to FIG. 1, which is a schematic diagram illustrating a portion of a data network 10, which is operative in accordance with a disclosed embodiment of the invention. The data network 10 has a RPR subnet 12 formed of RPR nodes 14, 16, 18, 20, 22. The RPR nodes 14, 16, 22 are interface nodes, interfacing with an external layer-3 network 24, which is typically an IP-aware network, and which may also have MPLS functions. The RPR nodes 18, 20 are non-interface nodes. Although five RPR nodes are shown representatively in FIG. 1, the invention can be practiced with other layer-2 subnets comprising any number of nodes. The data network 10 also has an external IP/MPLS node 26. The exemplary network 24 (30.30.30.0/24) is applicable to a method of choosing the exit point form each RPR network element, as is disclosed in further detail hereinbelow. Routers in the network 10, such as a router at the IP/MPLS node 26, build routing tables, each containing routing entries for specific destination networks and the specification of a hop to the next router along the path to the destination network. Table 2 is an example of such an entry. The destination in Table 2 is shown as a network address. This means that all IP packets to all hosts (in this case the RPR nodes 14, 16, 18, 20, 22) within the RPR subnet 12 (10.10.10.0) flow through the same path. TABLE 2 Destination Cost to network Destination mask Next hop IP destination 10.10.10.0 255.255.255.0 10.10.12.1 120 There are signaling protocols known in the art, such as RSPV-TE or LDP, which use the routing table to create virtual tunnels in the data network 10 with pre-defined reserved bandwidth along the routing path. These tunnels might be provisioned to use dynamic routes, as specified by the routing protocol, i.e., routes that are configured automatically (i.e., dynamically path-routed according to the IGP route) by the routers based on factors such as cost parameters assigned to different links. Protocols for route discovery are known as interior gateway protocols (IGP), such as OSPF, RIP, IS-IS. When different routes to the same destination have the same cost, the routers choose one of the routes arbitrarily, according to some predefined criterion. In a multi-access subnet, such as the RPR subnet 12 shown in FIG. 1, all nodes are configured to have the same cost (20). Therefore, the IP/MPLS node 26 would configure its routing database to point to the RPR subnet 12 (the destination network 10.10.10.0/24) via a single computed minimum cost next hop. Consequently, all signaled label-switched paths would always flow into the RPR subnet 12 via one, and only one, ring entry point. As mentioned above, layer-3 protocols, such as OSPF are unaware of the layer-2 RPR ring topology with multiple segments between two adjacent nodes. OSPF update dynamically updates the routing table of external routers, such as the IP/MPLS node 26, so as to route packets to the RPR subnet 12 via a single entry point based on minimum cost. In FIG. 1 the available entry points, RPR nodes 14, 16, 22, have identical costs of 100. The RPR node 14 (10.10.12.1) could be chosen as the entry point to the RPR subnet 12 arbitrarily. OSPF builds a topology database at the IP/MPLS node 26, and constructs an entry in the routing table, specifying routing to the RPR subnet 12 (10.10.10.0/24) via a next hop through the RPR node 14 (10.10.12.1) with a cost 120 (100+20). In this case since the IGP route specifies that all IP packets designated to the RPR subnet should flow through the address 10.10.12.1, any IP RSVP-TE path message packet that is configured to use a dynamic route will flow through this interface. Thus, all signaled LSP, i.e., MPLS tunnels, extending from the IP/MPLS node 26 (NEa) or other network elements within the MPLS “cloud”, to the RPR nodes 14, 16, 18, 20, 22 (NEb, NEc, NEd, NEe and NEf) will flow through one link 28, identified as subnet 10.10.12.0/24. There are two important disadvantages of this conventional behavior: First, all the tunnels utilize only one RPR entry link. The other two possible links via the RPR nodes 16, 22 remain unused. Second, the tunnels are configured on RPR spans without minimum hop ring entry awareness. For example, if a tunnel were to be established so as to reach the RPR node 20, it would have been preferred that the tunnel be configured dynamically via the RPR node 22 as an entry point, instead of the RPR node 14. Configuring the tunnel via the RPR node 22 would result in minimum RPR span utilization. This is apparent from the topology of the RPR subnet 12, wherein two RPR spans are required to reach the RPR node 20 from the RPR node 14, a first span connecting the RPR node 14 to the RPR node 22, and a second span connecting the RPR node 22 to the RPR node 20. Only one RPR span is required to reach the RPR node 20 from the RPR node 22. OSPF is not aware of the topology of the RPR subnet 12, and simply sees it as one layer-2 network. OSPF in conventional operation is thus unable to optimally route IP packets to each RPR network element with the number of RPR spans minimized, and therefore cannot configure a signaled MPLS tunnel via the shortest path through the layer-2 structure. In this sense, OSPF has no layer-2 visibility. Considering outbound traffic from the RPR subnet 12 to external routers and networks, such as the network 24, the same exit point for a particular destination network is utilized in conventional operation, regardless of the originating node of the RPR subnet 12. This is due to the fact that when OSPF constructs its internal database, three alternatives for the exit point, the RPR nodes 14, 16, 22, are considered. Assuming that the cost from each exit point (i.e., the RPR nodes 14, 16, 22) to the destination network 24 (30.30.30.0/24) is equal, each of the elements of the RPR subnet 12 will construct its routing table so that the same exit point is always chosen to that destination, without considering the number of RPR spans utilized to reach the chosen exit point, for example, the RPR nodes 16, 18, 20 will all have the following entry in their routing tables: 10.10.10.10, as shown in Table 3. TABLE 3 Destination Destination Cost to network mask Next hop IP destination 30.30.30.0 255.255.255.0 10.10.10.10 120 + Y In Table 3, the cost factor in the routing table entry from the RPR subnet 12 to the network 24 (30.30.30.0) is 120+Y, where Y is the cost to the destination in the IP/MPLS network beyond the IP/MPLS node 26 (NEa). In one aspect of the invention, the inventors have discovered how to overcome the above-mentioned disadvantages by manipulating the costs associated with different RPR nodes, so as to cause the routing tables of external layer-3 network elements, such as the IP/MPLS node 26 and other external routers (not shown), to point to different RPR-IP host address in the RPR subnet 12 via different entry points into the RPR ring. This technique can be used to cause virtual tunnels to be created dynamically, and other routing paths to utilize all existing entry links to the RPR subnet 12. The costs are typically manipulated using a metric that favors signaled LSP tunnels and other paths that cover the minimum number of hops (or least incur minimum cost) from the entry point to the desired RPR node. In another aspect of the invention, the same cost manipulation causes the host routing tables of the RPR nodes 14, 16, 18, 20, 22 in the RPR subnet 12 to select different respective RPR ring exit nodes for outbound IP traffic intended for the same destination network. The exit point that is selected for the RPR nodes 14, 16, 18, 20, 22 is based on minimum cost, taking into consideration the number of RPR spans required to reach the exit node. In the detailed examples given below, the metric is defined in such a way that the route selected is the one with the lowest metric score. Alternatively, many different metrics can be defined. For example, the metric may be defined so that the dynamic selection of ingress and exit points could be responsive to a maximum value of the metric. Ingress Routing. Reference is now made to FIG. 2, which is a flow diagram illustrating a method of obtaining ingress to a layer-2 subnet having a ring topology from a layer-3 network at different entry points in accordance with a disclosed embodiment of the invention. The subnet is a RPR subnet in the current embodiment, but could be other types of subnets having a ring topology. The method relies on addition of each RPR node's RPR—IP address (or alternatively, the node's IP loopback address) to the node's OSPF host table as defined by OSPF Version 2, Appendix C.7, and assigning a manipulated cost that is relative to the number of layer-2 RPR spans. The loopback address is a virtual IP address assigned to the RPR node, as distinguished from the RPR—IP address, which is assigned to the RPR interface. In some embodiments, signaling could be directed to the RPR—IP or the loopback IP address. Furthermore, the assigned relative cost is derived from the RPR reference topology, as defined in the above-noted IEEE standard 802.17. That is, each RPR node has a constructed RPR reference topology that specifies all other ring nodes, and their relative position within the RPR ring, i.e., the number of spans. The cost factor is based on the number of RPR spans between the RPR node and the entry point to the ring. The process steps that follow are shown with reference to a single RPR node. However, all RPR nodes in the ring that have at least one external MPLS link normally execute the process steps shown below independently and concurrently. At initial step 30, a RPR node of a RPR subnet examines its configuration with respect to the subnet topology. Control passes immediately to decision step 32, where the current node, chosen in initial step 30, determines if it has at least one IP external interface (e.g., the interface 10.10.12.1/24 of the RPR node 14 (FIG. 1)). If the determination at decision step 32 is negative, then control proceeds to final step 34, which is described below. If the determination at decision step 32 is affirmative, then at step 36 the current node updates its host routing table (OSPF Version 2, Appendix C.7) with all other mate RPR-IP nodes in the ring based on the RPR reference topology. This table indicates what hosts are directly attached to a router, and what metrics and types of service should be advertised for them. In embodiments employing OSPF Version 2, details of the host routing table are given in Appendix C.7 (RFC 2328) of the above-noted OSPF specification. All RPR host addresses that are specified in the RPR reference topology are added to the host routing table. The reference topology is updated with all IP RPR addresses within the RPR ring. For example, in FIG. 1, the RPR node 14 (NEb) has its RPR reference topology updated with IP addresses 10.10.10.10, 10.10.10.11, 10.10.10.12, 10.10.10.13, 10.10.10.14. Once updated in the OSPF host table, each host IP address (except for IP address of the RPR node 14) is advertised, as a 32-bit mask. Next, at step 38, each entry of the OSPF host table is updated to indicate the OSPF area to which the RPR node belongs. Next, at step 40, each entry added in step 36 is specified by a cost metric. In one embodiment, the metric is based on the following formula COSTm=K1*#OfHopsToNode'sIpAdd+K2. (1) K1 and K2 may be calculated as K1 = CostConfiguredOnRprIpInterface # OfNodesInReferenceTopology , ( 2 ) and K2=1. Alternatively, other values of K1, K2 may be calculated, wherein in Equation 1 and Equation 2: CostConfiguredonRprIpInterface is the actual cost configured by the operator on the IP interface of the RPR. For example, in each of the RPR nodes shown in FIG. 1, the cost is 20. #ofNodesInReferenceTopology is the number of nodes in the RPR ring, as listed in the node's reference topology. For example, the number of nodes in the RPR subnet 12 (FIG. 1) is five. #OfHopsToNode'sIpAdd is the number of RPR spans from the current node to the given destination node for the present entry, as indicated in the RPR reference topology via the shortest route (i.e., outer or inner ringlet direction). For example, in FIG. 1, if the current node is the RPR node 14, and the destination node for this entry is the RPR node 18 (IP address 10.10.10.12 in the OSPF host table), then #OfHopsToNode'sIpAdd=2. The operator “*” represents multiplication. Equation 1 and Equation 2 are representative of a formula for calculating a cost factor. Many alternative metrics and formulas can be applied in step 40. Next, at step 42 entries in the OSPF host table are flooded in the current OSPF area using router LSA packets. This step updates all external routers as well as all RPR nodes with the new entries. This step will cause the OSPF database to be synchronized in all participating OSPF areas. At step 44 all external routers, such as the IP/MPLS node 26 (FIG. 1) are informed by the router LSA packets that were transmitted in step 42 that there is a new route to the advertised hosts in the RPR subnet. Alternatively, advertising may be achieved using external LSA advertising as specified in OSPF Version 2, Section 12, Link State Advertisements. In this advertising method, each RPR node is added to the external LSA database with a 32-bit mask. Cost is calculated is described above, using Equation 1. Furthermore, although the embodiments described herein make use of OSPF, the methods of the present invention may similarly be adapted for use with other routing and control protocols. In either case, external routers now evaluate alternate paths to the nodes of a RPR subnet, based on the OSPF database updates that they received at step 42. Referring again to the example of FIG. 1, the IP/MPLS node 26 now sees four possible new paths to the RPR node 20 (RPR IP address 10.10.10.13/24): 1. Via the RPR node 14 (10.10.12.0) with cost, calculated using Equation 1 as 100+COSTm (of the RPR node 14): 100+COSTm=100+9=109; 2. Via the RPR node 22 (10.10.13.0) with cost of 100+COSTm=100+5=105; 3. Via the RPR node 16 (10.10.11.0) with cost of 100+COSTm=100+9=109; and 4. Via the link 28 and the RPR node 14 (10.10.12.0) with cost 100+20=120 (this is a route to network 10.10.10.0) Control now proceeds to final step 34, where a route to the RPR node is chosen. Typically, the external router will choose the path with a lowest cost. In the embodiment shown in FIG. 1, the selected path has the minimum number of hops. In still other embodiments, the cost factor is used to arbitrate among different paths all having the minimum number of hops. In the example of FIG. 1, in the current embodiment, the route chosen is via the RPR node 22 (10.10.13.0). This path, as seen in the example of FIG. 1, consumes the minimum number of layer-2 hops within the RPR ring. Egress Routing. The OSPF standard allows multiple equal-cost paths to exist to a destination, having different next hop addresses. Referring again to the example of FIG. 1, the RPR node 18 (NEd) has three different exit points from the RPR subnet 12, the RPR nodes 14, 16, 22. Each exit point is represented by a different next hop IP address entry in the OSPF routing table. Conventionally, the RPR node 18 would see each exit point as having the same cost 20 (the cost of the RPR interface). According to an embodiment of the present invention, however, the cost to each exit point is adjusted based on the number of RPR spans from the RPR node 18 to each exit point, in a manner similar to that described above with reference to FIG. 2. This results in different paths leading to the layer-3 network 24 having non-equal costs, depending on the different numbers of layer-2 RPR spans needed to exit from the RPR subnet 12 on each path. Typically, each node selects the path having the minimum total cost. As in ingress routing, the egress routing is disclosed with respect to a RPR subnet. However, the principles of this aspect of the invention are applicable to layer-2 subnets having ring topologies other than RPR subnets. Reference is now made to FIG. 3, which is a flow diagram illustrating a method of obtaining egress from a layer-2 subnet into a layer-3 network at different exit points in accordance with a disclosed embodiment of the invention. This method may be carried out simultaneously and in conjunction with the method of FIG. 2. The process steps that follow are shown with reference to a single RPR node. However, all RPR nodes in a ring normally execute the process steps shown below independently and concurrently. At initial step 46, a RPR node of the RPR subnet examines its OSPF routing table and selects groups consisting of at least two table entries. Each entry of a given group corresponds to a specific destination network, and involves more than one next hop to the destination network. This and the steps that follow apply not only to OSPF, but also to other routing protocols that support equal multi-path routing tables. Again, as in the flow chart presented in FIG. 2, the process shown in FIG. 3 is performed simultaneously for all RPR nodes. For example, in FIG. 1, each RPR node would have three entries in its OSPF routing table to a specific destination network, assuming that the cost from each exit point (the RPR nodes 14, 16, 22) to the specific destination network is equal. Next, at step 48, the RPR node updates its routing table. Entries (corresponding to routes) that were selected in initial step 46, are cost adjusted in accordance with Equation 1 and Equation 2. Next, at step 50, the routes adjusted in step 48 are analyzed by the RPR node. Next, at final step 52 an optimum path from the RPR node to an external node via an exit point of the RPR subnet is chosen. The metric enables the nodes of the ring to choose the best egress node for each external address. This is done in the same manner as in final step 34 (FIG. 2). The details are not repeated in the interest of brevity. Thereupon the procedure ends. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention relates to communications networks. More particularly, this invention relates to methods and systems for improved utilization of communications networks configured as layer-2 ring networks. 2. Description of the Related Art The meanings of acronyms and certain terminology used herein are given in Table 1. TABLE 1 AS Autonomous System ATM Asynchronous Transfer Mode. A network technology based on transferring data in cells or packets of a fixed size. FEC Forwarding equivalence class HDLC High-level Data Link Control IETF Internet engineering task force IGP Interior Gateway Protocol IP Internet protocol LAN Local Area Network LDP Label distribution protocol LLC Logical link congtrol LSA Link state advertisement LSP Label-switched path LSR Label-switching router MAC Media access control MPLS Multi-protocol label switching MPLS-TE MPLS traffic engineering OSI Open System Interconnection. A networking framework for implementing protocols. OSPF Open Shortest path First. A routing protocol OSPF-TE OSPF enhancements used in traffic engineering RFC Request for comments RIP Routing information protocol RPR Resilient packet rings - a protocol RSVP Resource reservation protocol RSVP-TE An extension of RSVP, used in traffic engineering SRP Spatial reuse protocol TE Traffic engineering TLV Type-Length-Value. An encoding scheme Local Area Networks (LAN's) connect computing systems together. LAN's of all types can be connected together using Media Access Control (MAC) bridges, as set forth in the “IEEE Standard for Information Technology, Telecommunications and Information Exchange between Systems, Local and Metropolitan Area Networks, Common Specifications, Part 3: Media Access Control (MAC) Bridges,” published as ANSI/IEEE Standard 802.1D (1998). The 802.1D standard is available via the Internet at the URL standards.ieee.org/catalog/IEEE802.1.html. Data networks, including LAN's, are commonly conceptualized as a hierarchy of layers according to the Open System Interconnection Model (OSI). OSI defines a networking framework for implementing protocols in seven layers, of which layer-3 (network layer), and layer-2 (data link layer) are relevant to the instant invention. Implementation of layer-3 requires high level knowledge of the network organization, and access to router tables that indicate where to forward or send data. This layer provides high level switching and routing technologies, and creates logical paths, known as virtual circuits, for transmitting data from node to node. In layer-3, data is transmitted by creating a frame that usually contains source and destination network addresses. Layer-2 encapsulates the layer-3 frame, adding more detailed data link control information to form a new, larger frame. Layer-2 implements a transmission protocol and handles flow control, frame synchronization, and handles errors arising in the physical layer (layer- 1 ). Layer-2 is divided into two sublayers: a media access control (MAC) sublayer and a logical link control (LLC) sublayer. The MAC sublayer controls how a computer on the network gains access to the data and its permission to transmit the data. The LLC layer controls frame synchronization, flow control and error checking. HDLC (High-level Data Link Control) is a related term that refers to a group of layer-2 protocols or rules for transmitting data between network points, known as nodes. In HDLC, data is organized into frames and sent across a network to a destination that verifies its successful arrival. The HDLC protocol also manages the flow or pacing at which data is sent. The Open Shortest Path First (OSPF) protocol is a link-state layer-3 routing protocol used for Internet routing. OSPF is described in detail by Moy in OSPF Version 2, published as Request for Comments (RFC) 2328 of the Internet Engineering Task Force (IETF) Network Working Group (April, 1998), which is incorporated herein by reference. This document is available at www.ietf.org, as are the other IETF RFC and draft documents mentioned below. OSPF is used by a group of Internet Protocol (IP) routers in an Autonomous System (AS) to exchange information regarding the system topology. The term “Autonomous System” denotes a group of routers exchanging routing information via a common routing protocol. Each OSPF router maintains an identical topology database, with exceptions as noted below. Based on this database, the routers calculate their routing tables by constructing a shortest-path tree to each of the other routers. Each individual piece of the topology database maintained by the OSPF routers describes the “local state” of a particular router in the Autonomous System. This local state includes information such as the router's usable interfaces and reachable neighbors. The routers distribute their local state information by transmitting a link state advertisement (LSA). Packets containing link state advertisements are flooded throughout the routing domain. The other routers receive these packets and use the LSA information to build and update their databases. OSPF allows collections of contiguous networks and hosts to be grouped together to form an OSPF area. An OSPF area includes routers having interfaces to any one of the grouped networks. Each area runs a separate copy of the basic link-state routing algorithm. The topology of an OSPF area is invisible from outside of the area. Conversely, routers internal to a given area does not know the detailed topology external to the area. This isolation of knowledge results in a marked reduction in routing traffic, as compared to treating the entire Autonomous System as a single link-state domain. A router in an Autonomous System has a separate topological database for each area to which it is connected. Routers connected to multiple areas are called area border routers. However, routers belonging to the same area have, for that area, identical area topological databases. An OSPF LSA database allows a layer-3 aware network element, such as a router, to build its routing table by running the well-known SPF algorithm. The element then routes IP packets based on the actual routing table and on the destination IP address in the IP packet header. A cost is associated with the output side of each router interface, and is used by the router in choosing the least costly path for the packets. This cost is configurable by the system administrator. The lower the cost, the more likely the interface is to be used to forward data traffic. For the purposes of cost calculation and routing, OSPF recognizes two types of networks (which may be organized as IP networks, subnets or supernets): point-to-point networks, which connect a single pair of routers; and multi-access networks, supporting two or more attached routers. Each pair of routers on a multi-access network is assumed to be able to intercommunicate directly. An Ethernet is an example of a multi-access network. Each multi-access network includes a “designated router,” which is responsible for flooding LSA's over the network, as well as certain other protocol functions. Further details concerning network cost calculation and routing are disclosed in application Ser. No. 10/211,066, (Publication No. 20030103449), which is commonly assigned herewith, and herein incorporated by reference. Multi-access layer-2 networks may be configured internally as rings. The leading bi-directional protocol for layer-2 high-speed packet rings is the Resilient Packet Rings (RPR) protocol, which is in the process of being defined as IEEE standard 802.17. Network-layer-routing over RPR is described, for example, by Jogalekar et al., in IP over Resilient Packet Rings (Internet Draft draft-jogalekar-iporpr- 00 ), and by Herrera et al., in A Framework for IP over Packet Transport Rings (Internet Draft draft-ietf-ipoptr-framework-00). A proposed solution for media access control (MAC protocol layer-2) in bi-directional ring networks is the Spatial Reuse Protocol (SRP), which is described by Tsiang et al., in the IETF document RFC-2892, entitled The Cisco SRP MAC Layer Protocol . Using protocols such as these, each node in a ring network can communicate directly with all other nodes through either an inner or an outer ring, using the appropriate Media Access Control (MAC) addresses of the nodes. The terms “inner” and “outer” are used arbitrarily herein to distinguish the different ring traffic directions. These terms have no physical meaning with respect to the actual configuration of the network. Multiprotocol Label Switching (MPLS) is gaining popularity as a method for efficient transportation of data packets over connectionless networks, such as Internet Protocol (IP) networks. MPLS is described in detail by Rosen et al., in Request for Comments (RFC) 3031 of the Internet Engineering Task Force (IETF), entitled “Multiprotocol Label Switching Architecture” (January, 2001). In conventional IP routing, each router along the path of a packet sent through the network analyzes the packet header and independently chooses the next hop for the packet by running a routing algorithm. In MPLS, however, each packet is assigned to a Forwarding Equivalence Class (FEC) when it enters the network, depending on its destination address. The packet receives a short, fixed-length label identifying the FEC to which it belongs. All packets in a given FEC are passed through the network over the same path by label-switching routers (LSR's). Unlike IP routers, LSR's simply use the packet label as an index to a look-up table, which specifies the next hop on the path for each FEC and the label that the LSR should attach to the packet for the next hop. Since the flow of packets along a label-switched path (LSP) under MPLS is completely specified by the label applied at the ingress node of the path, a LSP can be treated as a tunnel through the network. Such tunnels are particularly useful in network traffic engineering, as well as communication security. MPLS tunnels are established by “binding” a particular label, which is assigned at the ingress node to the network, to a particular FEC. Currently, layer-3 routing protocols, such as RIP and OSPF, are unaware of the topology of layer-2 RPR networks with which they must interact. A routing table allows the router to forward packets from source to destination via the most suitable path, i.e., lowest cost, minimum number of hops. The routing table is updated via the routing protocol, which dynamically discovers currently available paths. The routing table may also be updated via static routes, or can be built using a local interface configuration, which is updated by the network administrator. However, the RPR ingress and egress nodes chosen in the operation of automatic routing protocols do not take into account the internal links within the RPR ring, and may therefore cause load imbalances within the RPR subnet, which generally results in suboptimum performance of the larger network. | <SOH> SUMMARY OF THE INVENTION <EOH>According to a disclosed embodiment of the invention, methods and systems are provided for the manipulation of layer-3 network nodes, external routers, routing tables and elements of layer-2 ring networks, such as RPR networks, enabling the layer-3 elements to view the topology of a layer-2 ring subnet. This feature permits routers to choose optimal entry points to the layer-2 subnet for different routes that pass into or through the layer-2 subnet. This enables virtual tunnels or routing paths to utilize all existing entry links to the subnet and to minimize cost factors, such as the number of spans required to traverse the subnet from the entry point to a destination node of the subnet. In an aspect of the invention, the routing tables of RPR subnet elements are manipulated such that traffic routes originating in or passing through different elements of the RPR subnet and destined for network locations outside the RPR ring have individualized exit nodes. The exit points for the different routes are chosen to minimize cost factors, such as the number of spans required to reach the exit node from each node of the layer-2 subnet. The invention provides a method for obtaining ingress to a layer-2 ring network to reach nodes thereof, the nodes including ingress nodes that couple the ring network to an external layer-3 network, which is carried out in the ingress nodes by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric that is determined responsively to a topology of the ring network. Thereafter, the method is further carried out by uploading the host table to external elements of the layer-3 network, defining paths from the external elements to designated ones of the nodes of the ring network by selecting one of the ingress nodes for each of the paths responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. According to an aspect of the method, the ring network is a RPR subnet. According to an additional aspect of the method, the ingress nodes are selected responsively to a minimum value of the metric. According to another aspect of the method, the ingress nodes are selected responsively to a maximum value of the metric. In an additional aspect of the method, paths are defined in one or more of the external elements. The paths may be virtual tunnels. In one aspect of the method, the layer-3 network is an IP network, and uploading is achieved by flooding router LSA's with a mask, which can be a 32-bit mask. In another aspect of the method stub networks are flooded to achieve uploading. One aspect of the method uploading is performed by external LSA advertising to the layer-3 network. According to another aspect of the method, the metric includes a cost factor that is computed between one of the ingress nodes and the respective one of the nodes. According to yet another aspect of the method, the cost factor varies with a number of layer-2 spans between the one ingress node and the respective one of the nodes. In another aspect of the method paths are defined by computing a total cost based on the cost factor and on interface costs that are assigned in the layer-3 network, and selecting the paths so as to minimize the total cost. According to a further aspect of the method, the metric is determined responsively to a number of hops between the ingress nodes and the respective one of the nodes. According to another aspect of the method, the ingress nodes are configured with an interface cost on the layer-3 network, and the metric is determined proportionally to the interface cost and to the number of hops. According to a further aspect of the method, the ingress nodes are configured with an interface cost on the layer-3 network, and the metric is determined by the interface cost divided by the number of hops. The invention provides a computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, which is carried out by configuring ingress nodes of the ring network to create entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The method is further carried out by configuring the ingress nodes to thereafter upload the host table to external elements of a data network that interfaces with the ring network via the ingress nodes, configuring the external elements to define paths from the external elements to designated ones of the nodes of the ring network, each of the paths leading through a selected one of the ingress nodes responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. The invention provides a network routing system for obtaining ingress from an external layer-3 network to a layer-2 ring network to reach nodes thereof, including first routers disposed in ingress nodes of the ring network. The first routers are adapted for creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The first routers are further adapted for uploading the host table to external elements of a data network that interfaces with the ring network via the ingress nodes. A second router is disposed in at least one of the external elements. The second router is adapted for defining paths from the external elements to designated ones of the nodes of the ring network, each of the paths leading through a selected one of the ingress nodes responsively to the metric, and transmitting data from network elements that are external to the ring network to at least one of the nodes via a selected one of the paths. The invention provides a method for obtaining egress from a layer-2 ring network to an external layer-3 network, which is carried out in nodes of the ring network by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network, and a metric determined responsively to a topology of the ring network. The method is further carried out by defining paths from the nodes through egress nodes of the ring network to external elements in the external layer-3 network, selecting one of the paths responsively to the metric, and transmitting data from at least one of the nodes via the selected one of the paths to network elements that are external to the ring network. The invention provides a computer software product, including a computer-readable medium in which computer program instructions are stored, which instructions, when read by a computer, cause the computer to perform a method for obtaining egress from a layer-2 ring network to an external layer-3 network, which is carried out in nodes of the ring network by creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The method is further carried out by defining paths from the nodes through egress nodes of the ring network, selecting one of the paths responsively to the metric, and transmitting data from the nodes via the selected paths to network elements that are external to the ring network. The invention provides a network routing system for obtaining egress from a layer-2 ring network to an external layer-3 network, including a plurality of routers disposed in nodes of the ring network. The routers are adapted for creating entries in a host table, each of the entries including an address of a respective one of the nodes of the ring network and a metric. The routers are further adapted for defining paths from the nodes through egress nodes of the ring network, for selecting one of the paths responsively to the metric, and for transmitting data from the nodes via the selected paths to network elements that are external to the ring network. The invention provides a method for routing data through a layer-2 ring network, the ring network having interface nodes with external network elements of a data network and non-interface nodes, which is carried out in the interface nodes of the ring network by creating first entries in a first host table, each of the first entries including an address of a respective one of the non-interface nodes and a first metric. The method is further carried out by thereafter uploading the first host table to the external network elements, and using the first host table to identify optimum ingress paths from the external network elements to the non-interface nodes, each of the ingress paths leading through one of the interface nodes responsively to the first metric. The method is further carried out in the non-interface nodes of the ring network by creating second entries in a second host table, each of the second entries including an address of a respective one of the interface nodes and a second metric, using the second host table to identify optimum egress paths from the non-interface nodes through different ones of the interface nodes of the ring network responsively to the second metric, and transmitting data to and from the ring network via the ingress paths and the egress paths. | 20040329 | 20090623 | 20050929 | 58634.0 | 3 | JONES, PRENELL P | LAYER-3 NETWORK ROUTING WITH RPR LAYER-2 VISIBILITY | SMALL | 0 | ACCEPTED | 2,004 |
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10,812,586 | ACCEPTED | Recovery of sodium thiocyanate from industrial process solution using nanofiltration technique | The present invention relates to a membrane-based nanofiltration process for separating sodium thiocyanate (NaSCN) from industrial solution containing impurities such as β-sulfopropionic acid, β-sulfopropionitrile, sodium sulfate and salts of iron and calcium in a single step to obtain a colorless aqueous solution for spinning of acrylic fibre in textile industry. | 1. A process for recovery of sodium thiocyanate from industrial process solution containing undesirable components such as organic or inorganic compounds, color imparting ions and bivalent salts by membrane based nanofiltration technique said process comprising the steps of passing the industrial process solution as a feed solution through a nanofiltration member with simultaneous application of positive pressure to provide a pass solution and a permeate solution, wherein the permeate solution is substantially devoid of the undesirable components and evaporating the permeate solution to obtain sodium thiocyanate. 2. A process as claimed in claim 1 wherein the feed solution contains undesired components of bivalent, color imparting ions and other organic and inorganic compounds. 3. A process as claimed in claim 1 wherein the feed solution contains sodium thiocyanate in a concentration in excess of 100 gpl. 4. A process as claimed in claim 1 wherein the feed solution contains sodium thiocyanate in a concentration between 110 gpl and 120 gpl. 5. A process as claimed in claim 1 wherein organic components present in the feed solution is selected from the group consisting of β-Sulfo propionic acid and β-Sulfo propionitrile. 6. A process as claimed in claim 1 wherein the desired component in permeate is sodium thiocyanate. 7. A process as claimed in claim 1, wherein the process may comprise of multiple stages wherein the pass solution from a previous stage is diluted using distilled water and used as feed solution for a next stage. 8. A process as claimed in claim 1 and 7, wherein the feed solution or the diluted pass solution is passed through one or more nanofiltration membrane modules connected in series so as to produce second and/or subsequent pass solutions, consecutively, which are then finally disposed. 9. A process as claimed in claim 1, wherein the nanofiltration membrane used is selected from the group consisting of cellulose triacetate membrane, polyamide membrane and hydrophilised polyamide membrane. 10. A process as claimed in claim 1, wherein the nanofiltration membrane has active membrane area of about 1 m2. 11. A process as claimed in claim 1, wherein the pressure applied to the feed solution at the time of passing the same through the nanofiltration membrane is equal to or greater than osmotic pressure difference between the feed/pass solution on one side and the permeate solution of the other side of the membrane. 12. A process as claimed in claim 1, wherein the process is operated under flux whose value is in the range of 25 to 40 Lm2 hr−. | FIELD OF THE INVENTION The present invention relates to a process for the recovery of sodium thiocyanate from industrial process solution by membrane based nanofiltration technique. More particularly, the present invention relates to the separation of sodium thiocyanate (NaSCN) from undesirable compounds, particularly, color and bivalent salts from an aqueous industrial process solution by nanofiltration technique using a polymeric membrane. The present invention also relates to a process for substantially rejecting bivalent ions like sulfates, salts of Fe, Ca and other organic compounds like β-sulfo propionic acid, β-sulfo propionitrile during permeation of NaSCN with water. Sulfate ion is a common ingredient in these types of effluents. When such solution is used directly, the sulfate ions and other color imparting components deteriorate the fibre quality. Background and Prior Art Description: Reference may be made to U.S. Pat. No. 5,858,240, Twardowski, Zbigniew, Ulan and Judith issued on Jan. 12, 1999, which describes the removal of sodium chloride from concentrated aqueous solutions where sodium chloride is permeated with simultaneous rejection of other compounds like sodium sulfate to provide a pass solution with high concentration of multivalent ions. Reference may be made to U.S. Pat. No. 4,702,805, Burkell and Warren, issued on Oct. 27, 1987, which describes an improved method for the control of sulfate concentration in an electrolyte stream in a crystalline chlorate plant, whereby the sulfate is crystallized out. In the production of crystalline sodium chlorate according to U.S. Pat. No. 4,702,805, sodium chlorate is crystallized from sodium chlorate rich liquor. The crystals are removed to provide a mother liquor comprising principally of sodium chlorate and sodium chloride, together with other components, including sulfate and dichromate ions. A portion of the mother liquor is cooled to a temperature to effect crystallization of a portion of the sulfate as sodium sulfate in admixture with sodium chlorate. The crystallized admixture is removed and the resulting spent method liquor is recycled to the electrolytic process. Reference may be made to a process described in U.S. Pat. No. 4,702,805, wherein the crystallized admixture of sulfate and chlorate obtained from typical commercial liquors may be discolored yellow owing to the unexpected occlusion of a chromium component in the crystals. The discoloration cannot be removed by washing the separated admixture with liquors in which the crystallized sulfate and chlorate are insoluble. It will be appreciated that the presence of chromium in such a sulfate product is detrimental in subsequent utilization of this product and, thus, this represents a limitation to the process as described in U.S. Pat. No. 4,702,805. Reference may be made to U.S. Pat. No. 4,636,376—Maloney and Carbaugh, issued Jan. 13, 1987, which discloses a process for removing sulfate from aqueous chromate-containing sodium chlorate liquor without simultaneous removal of significant quantities of chromate. The chromate and sulfate-containing chlorate liquor having a pH in the range of about 2.0 to about 6.0 is treated with a calcium-containing material at a temperature range between about 40.degree. C. and 95.degree. C., for time period between 2 and 24 hours to form a sulfate-containing precipitate. The precipitate is predominantly glauberite, Na.sub.2 Ca (SO.sub.4).sub.2. However, the addition of calcium cations requires extra expenditure and effort for the treatment and removal of all excess calcium ions. It is known that calcium ions may form an unwanted deposit on the cathodes which increases the electrical resistance of the cells and adds to operating costs. The calcium ions are removed by means of ion exchange resins. Reference may be made to U.S. Pat. No. 4,415,677, which describes a method for sulfate ion adsorption. Typically, organic anion exchange resins have a low selectivity for sulfate anions in the presence of a large excess of chlorine ions. The method consists of removing sulfate ions from brine by a macroporous ion exchange resin composite having polymeric zirconium hydrous oxide contained in a vessel. This method has many disadvantages. This method is not economical because the efficiency is low and a large amount of expensive cation exchange resin is required for carrying zirconium hydrous oxide adsorbent. Further, the polymer loaded with zirconium hydrous oxide comes into contact with acidic brine containing sulfate ions, resulting in loss of the adsorbent due to acid-induced dissolution. Soluble zirconyl ions precipitates as hydroxide in the lower portion of the vessel and clogs flow paths. Reference may be made to U.S. Pat. No. 5,071,563—Shiga et al., issued Dec. 10, 1991, which describes the selective adsorption of sulfate anions from brine solutions using zirconium hydrous oxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. Reference may be made to Japanese Patent Kokai No. 04321514-A, published Nov. 11, 1992 to Kaneka Corporation, which describes the selective adsorption of sulfate anions from brine solutions using cerium hydroxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. Reference may be made to Japanese Patent Kokai No. 04338110-A—Kaneka Corporation, published Nov. 25, 1992, which describes the selective adsorption of sulfate anions from brine solutions using titanium hydrous oxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. The main drawbacks in these and other separation techniques like adsorption, ion exchange etc., which attempt to remove monovalent ions, is the failure of these systems to selectively and economically remove the monovalent ions in a single step from bivalent ions and organic compounds. Substantial portions of the commercially available anion exchange resins are required to sorb sulfate ions. Regeneration of the resins is similarly inefficient because of the need to desorb sulfate ions. The literature available from the patents describe only the removal of sodium chloride with respect to the Chlor alkali, brine and other industrial solutions. A proper process is absent for the color removal and selective separation of sodium thiocyanate from textile industries. Also the processes described have a very low flow rate which makes them unfeasible on a commercial scale. Therefore there still remains, a need for an improved, cost-effective, practical method for the removal of sulfate, silica, calcium and iron ions from alkali metal halide solutions, and also organic compounds present if any, particularly from these type of effluents which are used in the spinning of fibres for textile industries. OBJECTS OF THE INVENTION The main object of the present invention is to provide a process for the recovery of sodium thiocyanate from industrial process solution by membrane based nanofiltration technique, which obviates the drawbacks as detailed above. An object of the present invention is to provide a multi-stage process involving intermittent dilution of the feed with deionized water to facilitate maximum possible recovery of sodium thiocyanate in permeate with maximum rejection of impurities. A further object of the invention is to provide a process for reducing the color of the permeate solution. A still further object of the invention is to remove sodium sulfate from aqueous sodium thiocyanate solution used for spinning of acrylic fibre. A still further object of the invention is to remove Ca, Fe present in aqueous sodium thiocyanate solution used for spinning of acrylic fibre. Another object of the invention is the removal of β-Sulfo propionic acid, β-Sulfo propionitrile, low molecular weight polymer and other impurities present in the feed solution. Yet another object of the present invention is to identify a chemically resistant membrane, which yields maximum recovery of sodium thiocyanate at optimum flux with highest degree of impurity and color rejection. Still another object of the invention is to compare the performance of different Nanofiltration membranes amongst Cellulose triacetate, Polyamide, Hydrophilised polyamide, with respect to permeate flux and extent of impurity rejection achievable. Still further object of the present invention is to recover atleast 85-90% of the sodium thiocyanate in the permeate. A still further object is to optimize the pressure at which maximum enrichment of sodium thiocyanate in the permeate is achievable. Still another object of the present invention is to identify the ideal molecular weight cut-off for best membrane material that gives enrichment of sodium thiocyanate in permeate with rejection of 55-60% of the impurities. Still another object of the present invention is to identify the ideal membrane material that achieves color rejection of atleast 70%. Another object of the present invention is to identify the actual range of pressure at which the process can be operated that gives the maximum recovery of sodium thiocyanate. Another object of the present invention is to identify the dilution ratios for which maximum recovery of sodium thiocyanate can be achieved. Another object of the present invention is to identify the optimal flux ranges at which the variables of the system can be fixed. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS In the drawings accompanying this specification, FIG. 1 represents a diagrammatic flow sheet of a single stage nanofiltration membrane system for use in a process according to the invention. FIG. 2 represents a diagrammatic flow sheet of a multistage nanofiltration membrane system for use in a process according to the invention. FIG. 3 represents a diagrammatic flow sheet of the conductivity versus the concentration of sodium thiocyanate as described in the process according to the invention. DETAILED DESCRIPTION OF THE PRESENT INVENTION Accordingly, the present invention relates to a process for recovery of sodium thiocyanate from industrial process solution containing undesirable components such as organic or inorganic compounds, color imparting ions and bivalent salts by membrane based nanofiltration technique said process comprising the steps of passing the industrial process solution as a feed solution through a nanofiltration member with simultaneous application of positive pressure to provide a pass solution and a permeate solution, wherein the permeate solution is substantially devoid of the undesirable components and evaporating the permeate solution to obtain sodium thiocyanate. In an embodiment of the present invention, the feed solution contains undesired components of bivalent, color imparting ions and other organic and inorganic compounds. In another embodiment of the present invention, the feed solution contains sodium thiocyanate in a concentration in excess of 100 gpl. In yet another embodiment of the present invention, the feed solution contains sodium thiocyanate in a concentration between 110 gpl and 120 gpl. In still another embodiment of the present invention, wherein organic components present in the feed solution is selected from the group consisting of β-Sulfo propionic acid and β-Sulfo propionitrile. In one more embodiment of the present invention, the desired component in permeate is sodium thiocyanate. In one another embodiment of the present invention, the process may comprise of multiple stages wherein the pass solution from a previous stage is diluted using distilled water and used as feed solution for a next stage. In a further embodiment of the present invention, the feed solution or the diluted pass solution is passed through one or more nanofiltration membrane modules connected in series so as to produce second and/or subsequent pass solutions, consecutively, which are then finally disposed. In a further more embodiment of the present invention, the nanofiltration membrane used is selected from the group consisting of cellulose triacetate membrane, polyamide membrane and hydrophilised polyamide membrane. In another embodiment of the present invention, the nanofiltration membrane has active membrane area of about 1 m2. In yet another embodiment of the present invention, the pressure applied to the feed solution at the time of passing the same through the nanofiltration membrane is equal to or greater than osmotic pressure difference between the feed/pass solution on one side and the permeate solution of the other side of the membrane. In still another embodiment of the present invention, the process is operated under flux whose value is in the range of 25 to 40 Lm2 hr−1. The invention if further described in detail in the following paragraphs with reference to the accompanying drawings. FIG. 1 shown generally as S1, a single stage membrane nanofiltration system for the separation of, for example, sodium thiocyanate from aqueous solution. System S1 comprises a feed solution holding tank 1 connected to a nanofiltration membrane module, 6, by a feed conduit 15, through a high pressure pump, 4 (Prakash Pumps Ltd. Model I-2401). Module 6 comprises a single spiral wound type nanofiltration module containing either cellulose triacetate membrane, 23, PERMA-2521 polyamide membrane, 24, hydrophilised polyamide membrane-400, 25, having 1 m.sup.2 of active membrane area. Exiting module 6 is a pass recycle conduit, 14, used to recycle the pass stream to tank 1 having a pressure control valve, 8, and a permeate stream conduit 16. The process depicted in FIG. 1 represents a single stage or batch-type process, wherein the pass stream may be of sufficient and desired quality for use in a subsequent process or discharge. However, each of the pass, optionally, individually, may be sent through a nanofiltration membrane process again, in one or more cycles, in either a batch or continuous process. In industrial processes of use in the practice of the invention, the pass stream from the first stage may be sent to the second stage to increase the overall percentage recovery. Alternatively, the NF process may be conducted in a batch mode with the pass solution recycled back to the feed tank. Accordingly, in consequence, the feed composition will vary with time as will the membrane flux and possibly the percentage rejection. FIG. 2 shown generally as S2, represents a multi-stage NF method for the extraction of sodium thiocyanate from aqueous solution, according to the invention, wherein a plurality of NF membrane modules three in the embodiments shown and numbered 19A-19C, consecutively, are connected in series. Feed solution is fed under pressure by high pressure pump, 18A, to module 19A. Pass streams P1-P3 are passed to subsequent adjacent modules, wherein the streams are diluted accordingly with deionized water flowing through streams D1 and D2, and pressure control valves 20A-20C are used to maintain a constant pressure throughout the run. The permeate streams Pa-Pc may be combined into a single resultant purified permeate stream and the final pass stream, 22, may be sent for evaporation or may be collected. FIG. 3 shown generally as S3, represents the graph used to determine the concentration of the sodium thiocyanate in the feed, permeate and reject, during the course of the run. It was observed that the concentration of sodium thiocyanate attained from the graph was ±5% of values attained by potentiometric titration. In the present invention the feed solution is tested with different membrane modules like cellulose triacetate 23, polyamide 24, and hydrophilized polyamide (HPA-400) (Molecular weight cut-off 400) 25, to find the membrane which produces the best separation characteristics at optimum flux. The conductivity of the solutions is determined using a digital conductivity meter. The dilution ratio to which the reject liquor is to be treated after each stage of operation is determined, which is then processed as the feed solution for the next stage of operation. Also, the number of the stages involved to obtain the maximum recovery of sodium thiocyanate is determined. Further, the feed, permeate and pass streams are analyzed through potentiometric titration method to find the concentration of the desired component and other impurities. Ideal commercial membrane is chosen based on optimum flux attainable in association with highest degree of impurity rejection. Reverse osmosis (RO), ultrafiltration (UF) and nanofiltration (NF) are being used as pressure driven membrane process wherein organic molecules or inorganic ionic solutes in aqueous solutions are concentrated or separated to various degrees by the application of a positive osmotic pressure to one side of a filtration membrane. These processes employ a cross-flow mode of operation wherein only a portion of a feed solution (F) is collected as permeate solution (P) and the rest is collected as pass solution (R). When a separation of a compound from a solution containing impurities is required, a high percentage recovery of the compound and a high rejection of the impurities in association with high permeate flux is desired. Nanofiltration membranes are structurally very similar to Reverse osmosis membranes in that chemically, they, typically, are crosslinked aromatic polyamides, which are cast as a thin “skin layer”, on top of a microporous polysulfone polymer sheet support to form a composite membrane structure. The separation properties of the membrane are controlled by the pore size and electrical charge of the “skin layer”. Such a membrane structure is usually referred to as a thin film composite (TFC). However, unlike RO membranes, the NF membranes are characterized in having a larger pore size in its “skin layer” and a net negative electrical charge inside the individual pores. This negative charge is responsible for rejection of anionic species, according to the anion surface charge density. Accordingly, divalent anions, such as SO.sub.4.sup.-2, are more strongly rejected than monovalent ones, such as CN.sup.-. Commercial NF membranes are available from known suppliers of RO and other pressure driven membranes. Examples include: Permionics NF-2540 membranes (Permionics India Ltd., Baroda, Gujarat, India.), NF50, NF100, NF250 and NF400 HPA membranes. The NF membranes are, typically, packaged as membrane modules. A so-called “spiral wound” module is most popular, but other membrane module configurations, such as hollow fiber or tubular membranes are also known. Nanofiltration membranes have been reported to show zero or little rejection of low molecular weight organic molecules, such as, methanol, ethanol and ethylene glycol, but a significant rejection of higher molecular weight organic species, such as glucose. Among inorganic ionic solutes, low to medium rejection has been reported for simple electrolytes, such as NaCl or NaSCN and high rejection of other electrolytes where multivalent ionic species are involved, such as Na.sub.2 SO.subsub.4, MgCl.sub.2 and CaCl.sub.2. Such a characteristic differentiates NF from RO, which rejects all ionic species, and from ultrafiltration (UF), which does not reject ionic species and only rejects organic compounds with molecular weights, typically, in excess of 1,000. During the NF process, a minimum pressure equal to the osmotic pressure difference between the feed/pass solution on one side and the permeate solution on the other side of the membrane must be applied since osmotic pressure is a function of the ionic strengths of the two streams. In the case of separation of a multivalent solute, such as Na.sub.2 SO.sub.4, from a monovalent one, such as NaSCN, the osmotic pressure difference is moderated by the low NaSCN rejection. Usually, a pressure in excess of the osmotic pressure difference is employed to achieve practical permeate flux. In view of lower NaSCN rejection, NF has been used successfully for removal of sulfate and the cations contributing to hardness, Ca.sup.2+ and Mg.sup.2+ from brackish waters and even seawater, without the necessity to excessively pressurize the feed stream. The reported typical pressure range for NF is 100 to 300 psi, although membrane elements are designed to withstand pressures up to 600 psi. The process adopted by the industries involves the usage of Activated carbon Filter and Leaf Filter for the removal of some of the impurities present along with sodium thiocyanate in the aqueous solution. The cake of the Leaf Filter is rich in NaSCN, which is then dissolved in water, centrifuged and the filtrate of the centrifuge is sent to a Gel Filtration Column, wherein the remaining impurities are removed by chromatographic separation. The entire process involves the usage of many stages and proves uneconomical with a very low flow rate and recovery. Accordingly, the present invention provides a nanofiltration process for the recovery of sodium thiocyanate from industrial process solution by processing the feed solution through a nanofiltration membrane module under a positive pressure to provide a reject containing the impurities and color and a permeate containing enriched sodium thiocyanate solution. The processes of the invention, as hereinabove defined, may comprise further treatment of the reject stream. For example, the reject is diluted and further treated with nanofiltration membranes to extract the remaining sodium thiocyanate for higher recovery and a final reject stream with negligible concentration of sodium thiocyanate for disposal. The processes of the invention are applicable as either single stage batch processes with optional recycle of either pass liquor or permeate liquor to the nanofiltration membrane module, or as part of a multi-stage, multi-module system. The processes of the invention are applicable as the pass stream is further diluted in a multistage operation wherein the remaining desired monovalent ion is further extracted in the subsequent stage. The process of the invention as hereinabove defined may be operated at any suitable and desired temperature selected from 27. degree.C to 38. degree.C. of the feed stream; and positive pressures applied to the feed side, generally selected from 100-600 psi. The process of the invention as hereinabove defined may be operated at an optimum flux of 25-40 lit.m.sup.-2.hr.sup.-1. Flux below 10 lit.m.sup.-2.hr.sup.-1, will be uneconomical unless the product is too expensive. Flux greater than 45 lit.m.sup.-2.hr.sup.-1, is avoided to minimize the concentration polarization and fouling due to rapid increase in concentration of solute molecules on the membrane surface. Preferably, the sodium thiocyanate is at a concentration of greater than 100 gpl, more preferably greater than 110 gpl in the initial feed solution. The following examples are given by way of illustration to portray the efficacy of the separation characteristics of the Nanofiltration membrane in separating NaSCN as described by FIG. 1 and FIG. 2 wherein data was collected using an experimental NF test rig which consisted of a single NF membrane filter element, 2.5″ diameter, 21″ long, containing Permionics CTA, 23, for batch operation, and polyamide, 24, and HPA 400 membrane, 25, for continuous operation, from Permionics India Ltd. The active membrane area was 2.5 m.sup.2. All runs were conducted at temperature 27.degree.-32.degree. C. and therefore should not be construed to limit the scope of the present invention. EXAMPLE 1 A batch of 50 litres containing 135.1 gpl of NaSCN at 30.degree.C. was fed to feed tank 1. High-pressure pump, 4, was turned on and the pressure on the feed side was maintained at 21 bar throughout the run. The feed was processed through a Cellulose triacetate membrane, 23, and following the run, permeate was collected in separate tank over a period of 86 minutes. The pass stream flow rate was kept constant at 17 litres per minute. A recovery of 60% was collected as permeate volume with an average flux between 28 lit.m.sup.-2.hr.sup.-1 and 29 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 76.5% and 66.4% respectively. The feed, pass and permeate samples were analyzed for NaSCN and color and the results are tabulated in table 1 given below. TABLE 1 Quality parameters Feed Permeate Pass NaSCN(%) 13.51 16.88 11.27 % Total impurities 5.54 3.17 9.42 Color APHA 98 23 209 EXAMPLE 2 A batch of 30 litres of feed solution containing 129 gpl of sodium thiocyanate is diluted in the ratio 1:0.5, reducing the concentration of sodium thiocyanate to 86 gpl, thereby making the volume to 45 litres and was fed to feed tank, 17, at a temperature of 28. degree.C. High pressure pump, 18A, was turned on and the pressure on the feed side was adjusted to 24 bar using pressure control valve 20A and was maintained constant during the run. The feed was processed through a polyamide (PA-300), 24, spiral wound membrane module 19A. The pass stream flow rate was kept constant at 17 litres per minute whereas the permeate flow rate 26A varied during the run. 27 litres of permeate volume was collected in a separate tank 27A over a period of 254 minutes for a volume recovery of 60%. The impurity and color rejections were found to be 94% and 97% respectively. The remaining 18 litres was left in the tank and within the system. The feed stream, pass stream and permeate stream are analyzed for % NaSCN, % total impurities and color and results are tabulated in Table 2 given below. TABLE 2 Quality Parameters Feed Permeate Pass NaSCN (Conc %) 8.6 10.33 6.54 Total impurities (%) 5.54 0.54 11.26 βSPA (%) 0.06 0.04 0.11 βSPN (%) 0.24 Nil 0.4 Na2SO4 4.68 0.38 9.77 NaCl (%) 0.07 0.06 0.06 Fe (ppm) 0.46 0.14 0.58 Ca(ppm) 72.4 31.0 154 APHA 198 4.0 413 EXAMPLE 3 In this Example, the pass stream P1 of Example 2 was diluted with distilled water in the ratio 1:0.5 and a total volume of 30 litres containing 37.3 gpl of NaSCN was run through a polyamide membrane module 19B. Pressure on the feed side was adjusted to 24 bar using pressure control valve 20B and was maintained constant during the run. The pass stream flow rate was constant during the run at 17 litres per minute. 15 litres of the permeate was collected for a duration of 172 minutes obtaining an overall volume recovery of 50%. The impurity and color rejections were found to be 95% and 98% respectively. The feed stream, pass stream and permeate stream were analyzed for % NaSCN, % total impurities and color and results are tabulated in Table 3. TABLE 3 Quality Parameters Feed Permeate Pass NaSCN Conc (%) 3.73 5.3 2.57 Total impurities (%) 6.26 0.67 11.13 βSPA (%) 0.14 0.08 0.27 βSPN (%) 0.10 0.06 0.32 Na2SO4 5.69 0.42 10.14 NaCl (%) 0.07 0.03 0.07 Ca(ppm) 80.6 11.65 155 Color(APHA units) 239 3.0 447 EXAMPLE 4 In this Example, the pass stream P2 of the Example 3 was diluted using distilled water in the ratio 1:0.75 and a total volume of 20 litres containing 11.9 gpl of NaSCN was run through polyamide membrane module 19C. The pressure was maintained using a pressure control valve 20C at 24 bar. 10 litres of permeate is collected with an overall volume recovery of 50%. The impurity and color rejections were found to be 97% and 98% respectively. The feed, pass and permeate samples were analyzed for % NaSCN, % total impurities and color and the results are tabulated in Table 4. TABLE 4 Quality Parameters Feed Permeate Pass NaSCN (conc %) 1.19 1.84 0.73 Total impurities (%) 5.06 0.25 8.48 βSPA (%) 0.49 0.09 0.92 βSPN (%) 0.15 0.03 0.22 Na2SO4 4.27 0.08 7.16 NaCl (%) 0.05 0.04 0.04 Fe (ppm) 0.31 NA 0.42 Ca(ppm) 84.3 10.2 167 Color (APHA) 234 13 422 The average flux for Examples 2-4 ranged from 5 lit.m.sup.-2.hr.sup.-1 and 10 lit.m.sup.-2.hr.sup.-1. EXAMPLE 5 Comparative Example of HPA-400 Batch and Continuous Processes In the batch operation, the original feed containing 120 gpl of NaSCN was fed to a feed tank 1. High-pressure pump 4 was turned on and maintained at 24 bar throughout the process using pressure control valve, 8. The feed solution is then passed through HPA-400 spiral wound membrane module no 6 and the pass stream flow rate maintained at 17 litres per minute was recycled back into the feed tank. An overall volume recovery of 60% consisting of 129.1 gpl of NaSCN was achieved with an average flux in between 64 lit.m.sup.-2.hr.sup.-1 and 69 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 97% and 73% respectively. In continuous operation a second batch feed containing 114.6 gpl of NaSCN is fed to the tank 1. High-pressure pump, 18A, was turned on and was maintained constant at 24 bar for the entire run using pressure control valve 20A. The feed solution was then passed through membrane module 19A containing HPA-400, membrane 25. The pass stream flow rate was maintained at 2 litres per minute and then fed to the next membrane module. A recovery by volume of 60% was achieved with respect to this membrane module no 19A in a time period of 70 min with an average flux in between 39 lit.m.sup.-2.hr.sup.-1 and 40 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 80% and 72% respectively. The comparison of % rejection, % NaSCN and % total impurities of batch and continuous operation are tabulated in Table 5 given below. TABLE 5 Hydrophilized polyamide Hydrophilized polyamide HPA-400 HPA-400 Quality Continuous mode Batch mode parameters Feed Permeate Pass Feed Permeate Pass NaSCN % 11.46 12.25 10.28 11.84 12.91 10.7 Color 179 35 409 241 8.0 530 % Total 4.58 2.15 7.28 5.39 2.48 9.04 Impurities EXAMPLE 6 The pass stream from Comparative Example 1, operated in batch mode was diluted in the ratio 1:1 with distilled water and the resulting feed solution containing 57.1 gpl of NaSCN was fed to membrane module, 6, containing hydrophilized polyamide membrane (HPA-400), 25. High pressure pump, 4, was turned on and the pressure was maintained at 24 bar. The pass stream was recycled back at a constant flow rate of 17 litres per minute. An overall volume recovery of 50% was achieved with an average flux in between of 79 lit.m.sup.-2.hr.sup.-1 and 80 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 95% and 80% respectively. The pass stream from Comparative Example 5, operated in a continuous mode, was diluted in the ratio 1:0.75 with deionized water passing through conduit D1. The resulting solution containing 62.9 gpl of NaSCN was fed to membrane module 19B. The pressure control valve 20B was used to maintain feed pressure at 24 bar and the pass flow rate was kept at 2 litres per minute. An overall volume recovery of 60% was achieved with an average flux in between 40 lit.m.sup.-2.hr.sup.-1 and 42 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 93% and 72% respectively. The comparison of the results for the batch and continuous process is given in Table 6 below. TABLE 6 Hydrophilized polyamide Hydrophilized polyamide HPA-400 HPA-400 Quality Continuous mode Batch mode parameters Feed Permeate Pass Feed Permeate Pass NaSCN 6.29 7.43 5.73 5.71 6.59 5.14 (%) Color 275 20 641 298 14 623 (APHA) Total 4.63 2.16 7.26 4.90 1.93 7.61 impurities (%) EXAMPLE 7 The pass stream from Comparative Example 2, operated in batch mode was diluted in the ratio 1:1 with deionized water and the resulting feed solution containing 28.7 gpl of NaSCN was fed to membrane module no 6 containing HPA-400, 25. The pressure was maintained at 24 bar. An overall volume recovery of 60% was achieved with an average flux in between 53 lit.m.sup.-2.hr.sup.-1 and 54 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 96% and 79% respectively. The pass stream from Comparative Example 2, operated in continuous mode was diluted by conduit D2 in the ratio 1:0.75 and the resulting solution containing 32.3 gpl NaSCN was fed to a membrane module no. 19C containing HPA-400, 25. The pressure control valve 20. degree.C was adjusted to maintain a feed pressure of 24 bar and the reject flow rate was maintained at 2 litres per minute. An overall volume recovery of 60% was achieved with an average flux in between 34 lit.m.sup.-2.hr.sup.-1 and 35 lit.m.sup.-2.hr.sup.-1. The color and impurity rejections were found to be 96% and 77% respectively. The comparison of the results for the batch and continuous process is in Table 7 below. TABLE 7 Hydrophilized polyamide Hydrophilized polyamide HPA-400 HPA-400 Quality Continuous mode Batch mode parameters Feed Permeate Pass Feed Permeate Pass NaSCN 3.23 3.73 2.43 2.87 3.55 2.42 (%) Color 571 23 472 316 12 678 (APHA) Total 3.91 1.23 6.9 4.12 1.48 5.06 impurities (%) The drawback of the batch and continuous process employed, is the excess addition of distilled water which reduced the overall sodium thiocyanate concentration in the permeate. The dilution ratio has to be optimized in order to achieve maximum recovery of sodium thiocyanate in permeate and also to maintain a concentration of 10% of NaSCN in the permeate solution. This study showed that the percentage rejection of impurities and color is similar for both batch and continuous process for each stage of operation. EXAMPLE 8 A batch of 60 litres of feed volume containing 120 gpl of NaSCN was fed to a feed tank no-17. High pressure pump 18A was turned on and the feed solution was fed to module no 19A containing HPA-400, 25, by adjusting the feed side pressure to 18 bar using pressure control valve 20A, which was maintained constant during the run. 30 litres of the permeate was collected for a duration of 49 minutes obtaining a recovery by volume of 50%. The color and impurity rejections were found to be 85% and 79% respectively. The feed, permeate and pass samples were analyzed for NaSCN, color and total impurities and are as shown in Table 8 below. TABLE 8 Hydrophilized polyamide membrane (HPA-400) Quality parameters Feed Permeate Pass NaSCN (Conc %) 12.1 13.49 10.17 Total impurities (%) 5.33 2.2 8.16 Color (APHA units) 221 23 418 EXAMPLE 9 In this example, the pass stream of the Example 5 was diluted with distilled water flowing through the conduit D1 in the ratio 1:0.5. A starting volume of 42 litres containing 79 gpl of NaSCN was fed to module no. 19B containing HPA-400 membrane, 25. High-pressure pump, 18B, was turned on and the pressure on the feed side was adjusted to 18 bar and was maintained constant during the run. 15 litres of the permeate was collected for a duration of 30 minutes obtaining an overall volume recovery of 50%. The color and the impurity rejections were found to be 96% and 77% respectively. The feed stream, pass stream and permeate stream were analyzed for % NaSCN, % total impurities and color and results are shown in Table 9 below. TABLE 9 Hydrophilized Polyamide membrane (HPA-400) Quality parameters Feed Permeate Pass NaSCN (conc %) 7.9 9.02 7.14 Total impurities (%) 5.54 2.53 8.37 Color (APHA units) 276 10 521 EXAMPLE 10 In this example, the reject from Example 6 was further diluted in the ratio 1:0.75. 30 litres of the solution having a composition 45.4 gpl of NaSCN was fed through module no 19C containing HPA-400 membrane, 25. High pressure pump, 18C, was turned on and was maintained at 18 bar during the run. 18 litres of permeate was collected achieving an overall volume recovery of 60%. The color and impurity rejections were found to be 79% and 72% respectively. The feed, pass and permeate samples are analyzed for % NaSCN, % impurities and color and the results are shown in Table 10 herebelow. TABLE 10 Hydrophilized polyamide membrane (HPA-400) Quality parameters Feed Permeate Pass NaSCN (Conc %) 4.54 5.48 — Total impurities (%) 5.14 2.45 8.37 Color (APHA units) 277 57 601 The average flux for Examples 5-7 varied between 35 lit.m.sup.-2.hr.sup.-1 and 54 lit.m.sup.-2.hr.sup.-1. The analyzed permeate samples at this pressure showed considerably high concentration of NaSCN in permeate, with acceptable color and impurity rejections at a pressure of 18 bar. This experiment was carried out at 18 bar to find the optimal range of pressure at which the system can be operated which gives acceptable rejection of impurities so that the operating costs can be minimized. EXAMPLE 11 In this example, performance of the various membrane materials are compared. The results of the comparison are given in Table 11 given herebelow. TABLE 11 NaSCN % Total Color Membrane % impurities (APHA) Flux range material F P R F P R F P R L/m2hr Cellulose 13.51 16.88 11.27 5.54 3.17 9.42 98 23 209 28-30 triacetate (CTA-1000) Single stage only Polyamide 8.6 10.33 6.54 5.54 0.54 11.26 198 4 413 8-10 (PA-300) stage-1 Polyamide 3.73 5.3 2.57 6.26 0.67 11.13 239 3 447 6-8 (PA-300) stage-2 Polyamide 1.19 1.84 0.73 5.06 0.25 8.48 234 13 422 8-10 (PA-300) stage-3 Hydrophilized 12.1 13.49 10.17 5.33 2.2 8.16 221 23 418 35-40 polyamide (HPA-400) stage-1 Hydrophilized 7.9 9.02 7.14 5.54 2.53 8.37 276 10 521 41-48 polyamide (HPA-400) stage-2 Hydrophilized 4.54 5.48 — 5.14 2.45 8.37 277 57 601 49-54 polyamide (HPA-400) stage-3 Experiment with cellulose triacetate was carried only for a single stage because the percentage impurity in the permeate is quite high which shows the low rejection of impurities and also presence of color in the permeate sample makes it unacceptable as per the guidelines. So further experiments with CTA were not carried out. | <SOH> FIELD OF THE INVENTION <EOH>The present invention relates to a process for the recovery of sodium thiocyanate from industrial process solution by membrane based nanofiltration technique. More particularly, the present invention relates to the separation of sodium thiocyanate (NaSCN) from undesirable compounds, particularly, color and bivalent salts from an aqueous industrial process solution by nanofiltration technique using a polymeric membrane. The present invention also relates to a process for substantially rejecting bivalent ions like sulfates, salts of Fe, Ca and other organic compounds like β-sulfo propionic acid, β-sulfo propionitrile during permeation of NaSCN with water. Sulfate ion is a common ingredient in these types of effluents. When such solution is used directly, the sulfate ions and other color imparting components deteriorate the fibre quality. Background and Prior Art Description: Reference may be made to U.S. Pat. No. 5,858,240, Twardowski, Zbigniew, Ulan and Judith issued on Jan. 12, 1999, which describes the removal of sodium chloride from concentrated aqueous solutions where sodium chloride is permeated with simultaneous rejection of other compounds like sodium sulfate to provide a pass solution with high concentration of multivalent ions. Reference may be made to U.S. Pat. No. 4,702,805, Burkell and Warren, issued on Oct. 27, 1987, which describes an improved method for the control of sulfate concentration in an electrolyte stream in a crystalline chlorate plant, whereby the sulfate is crystallized out. In the production of crystalline sodium chlorate according to U.S. Pat. No. 4,702,805, sodium chlorate is crystallized from sodium chlorate rich liquor. The crystals are removed to provide a mother liquor comprising principally of sodium chlorate and sodium chloride, together with other components, including sulfate and dichromate ions. A portion of the mother liquor is cooled to a temperature to effect crystallization of a portion of the sulfate as sodium sulfate in admixture with sodium chlorate. The crystallized admixture is removed and the resulting spent method liquor is recycled to the electrolytic process. Reference may be made to a process described in U.S. Pat. No. 4,702,805, wherein the crystallized admixture of sulfate and chlorate obtained from typical commercial liquors may be discolored yellow owing to the unexpected occlusion of a chromium component in the crystals. The discoloration cannot be removed by washing the separated admixture with liquors in which the crystallized sulfate and chlorate are insoluble. It will be appreciated that the presence of chromium in such a sulfate product is detrimental in subsequent utilization of this product and, thus, this represents a limitation to the process as described in U.S. Pat. No. 4,702,805. Reference may be made to U.S. Pat. No. 4,636,376—Maloney and Carbaugh, issued Jan. 13, 1987, which discloses a process for removing sulfate from aqueous chromate-containing sodium chlorate liquor without simultaneous removal of significant quantities of chromate. The chromate and sulfate-containing chlorate liquor having a pH in the range of about 2.0 to about 6.0 is treated with a calcium-containing material at a temperature range between about 40.degree. C. and 95.degree. C., for time period between 2 and 24 hours to form a sulfate-containing precipitate. The precipitate is predominantly glauberite, Na.sub.2 Ca (SO.sub.4).sub.2. However, the addition of calcium cations requires extra expenditure and effort for the treatment and removal of all excess calcium ions. It is known that calcium ions may form an unwanted deposit on the cathodes which increases the electrical resistance of the cells and adds to operating costs. The calcium ions are removed by means of ion exchange resins. Reference may be made to U.S. Pat. No. 4,415,677, which describes a method for sulfate ion adsorption. Typically, organic anion exchange resins have a low selectivity for sulfate anions in the presence of a large excess of chlorine ions. The method consists of removing sulfate ions from brine by a macroporous ion exchange resin composite having polymeric zirconium hydrous oxide contained in a vessel. This method has many disadvantages. This method is not economical because the efficiency is low and a large amount of expensive cation exchange resin is required for carrying zirconium hydrous oxide adsorbent. Further, the polymer loaded with zirconium hydrous oxide comes into contact with acidic brine containing sulfate ions, resulting in loss of the adsorbent due to acid-induced dissolution. Soluble zirconyl ions precipitates as hydroxide in the lower portion of the vessel and clogs flow paths. Reference may be made to U.S. Pat. No. 5,071,563—Shiga et al., issued Dec. 10, 1991, which describes the selective adsorption of sulfate anions from brine solutions using zirconium hydrous oxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. Reference may be made to Japanese Patent Kokai No. 04321514-A, published Nov. 11, 1992 to Kaneka Corporation, which describes the selective adsorption of sulfate anions from brine solutions using cerium hydroxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. Reference may be made to Japanese Patent Kokai No. 04338110-A—Kaneka Corporation, published Nov. 25, 1992, which describes the selective adsorption of sulfate anions from brine solutions using titanium hydrous oxide slurry under acidic conditions. The ion exchange compound may be regenerated by treatment with alkali. The main drawbacks in these and other separation techniques like adsorption, ion exchange etc., which attempt to remove monovalent ions, is the failure of these systems to selectively and economically remove the monovalent ions in a single step from bivalent ions and organic compounds. Substantial portions of the commercially available anion exchange resins are required to sorb sulfate ions. Regeneration of the resins is similarly inefficient because of the need to desorb sulfate ions. The literature available from the patents describe only the removal of sodium chloride with respect to the Chlor alkali, brine and other industrial solutions. A proper process is absent for the color removal and selective separation of sodium thiocyanate from textile industries. Also the processes described have a very low flow rate which makes them unfeasible on a commercial scale. Therefore there still remains, a need for an improved, cost-effective, practical method for the removal of sulfate, silica, calcium and iron ions from alkali metal halide solutions, and also organic compounds present if any, particularly from these type of effluents which are used in the spinning of fibres for textile industries. | <SOH> BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS <EOH>In the drawings accompanying this specification, FIG. 1 represents a diagrammatic flow sheet of a single stage nanofiltration membrane system for use in a process according to the invention. FIG. 2 represents a diagrammatic flow sheet of a multistage nanofiltration membrane system for use in a process according to the invention. FIG. 3 represents a diagrammatic flow sheet of the conductivity versus the concentration of sodium thiocyanate as described in the process according to the invention. detailed-description description="Detailed Description" end="lead"? | 20040329 | 20080101 | 20050929 | 63662.0 | 0 | LANGEL, WAYNE A | RECOVERY OF SODIUM THIOCYANATE FROM INDUSTRIAL PROCESS SOLUTION USING NANOFILTRATION TECHNIQUE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,748 | ACCEPTED | Vehicle transporter with screw actuators | Vehicular cargo of a vehicle transporter is supported by elongate vehicle support members. Elevated vehicle support members are supported above the vehicular frame of the transporter and moved by screw actuators that are self-locking. | 1. A vehicle transporter comprising: (a) a vehicular frame; (b) a vehicle support member movable relative to said vehicular frame; and (c) a screw actuator having elongate members that slide longitudinally relative to each other in response to turning of a screw so as to alter a length of said actuator, and having a connection to said vehicular frame and a connection to said vehicle support member so that altering said length of said screw actuator will cause said vehicle support member to move relative to said vehicular frame. 2. The vehicle transporter of claim 1 wherein said screw actuator comprises: (a) a tubular shell connectible to one of said vehicular frame and said vehicle support member, said tubular shell comprising a wall defining an exterior and an interior; (b) a slide tube having a first end a connectible to the other of said vehicular frame and said vehicle support member, a second end, and a slide tube wall connecting said first end and said second end and defining a slide tube interior and a slide tube exterior, said slide tube exterior being slidably arranged in said interior of said tubular shell; (c) a guide in sliding engagement with said slide tube interior; (d) a screw having a threaded portion, a first end arranged for rotation of said screw in said interior of said tubular shell, and a second end rotatably supported by said guide; and (e) a nut constrained to translate with said slide tube and in threaded engagement with said threaded portion of said screw so that rotation of said screw will cause said slide tube to translate in said tubular shell altering said length of said screw actuator. 3. The vehicle transporter of claim 2 wherein said screw actuator further comprises a follower nut in threaded engagement with said screw and in sliding engagement with said interior of said tubular shell. 4. The vehicle transporter of claim 2 wherein said screw actuator further comprises a motor including a frame connected to said tubular shell and a shaft rotatable in said frame and drivingly connected to rotate said screw. 5. The vehicle transporter of claim 2 wherein said threaded portion of said screw is arranged so that said threaded engagement of said nut and said screw is self-locking to prevent forces tending to translate said slide tube from causing rotation of said screw. 6. The vehicle transporter of claim 2 wherein said threaded portion of said screw comprises an Acme thread having a lead angle not exceeding five degrees. 7. The vehicle transporter of claim 2 wherein at least one of said tubular shell and said slide tube is connectible to one of said vehicular frame and said vehicle support member by a pivotal connection. 8. The vehicle transporter of claim 7 wherein said screw actuator further comprises a follower nut in threaded engagement with said screw and in sliding engagement with said interior of said tubular shell. 9. The vehicle transporter of claim 7 wherein said screw actuator further comprises a motor including a frame attached to said tubular shell and a shaft rotatable in said frame and drivingly connected to rotate said screw. 10. The vehicle transporter of claim 9 wherein said tubular shell is connectible to one of said vehicular frame and said vehicle support member with a pivoting connection enabling said motor and said tubular shell to pivot in unison. 11. The vehicle transporter of claim 7 wherein said threaded portion of said screw is arranged so that said threaded engagement of said nut and said screw is self-locking to prevent forces tending to translate said slide tube from causing rotation of said screw. 12. A vehicle transporter comprising: (a) a vehicular frame; (b) a vehicle support member having a pivotally supported first end and a second end; and (c) a screw actuator having elongate members that slide longitudinally relative to each other in response to turning of a screw so as to alter a length of said actuator, and having a connection to said vehicular frame and a connection to said vehicle support member so that altering said length of said screw actuator will cause at least said second end of said vehicle support member to move relative to said vehicular frame. 13. The vehicle transporter of claim 12 wherein said screw actuator comprises: (a) a tubular shell pivotally connectible to one of said vehicular frame and said vehicle support member, said tubular shell comprising a wall defining an exterior and an interior; (b) a slide tube having a first end, said first end having a pivotal connection to the other of said vehicular frame and said vehicle support member; a second end; and a slide tube wall connecting said first end and said second end and defining a slide tube interior and a slide tube exterior, said slide tube exterior being slidably arranged in said interior of said tubular shell; (c) a guide in sliding engagement with said slide tube interior; (d) a screw having a threaded portion, a first end arranged for rotation of said screw in said interior of said tubular shell, and a second end rotatably supported by said guide; and (e) a nut constrained to translate with said slide tube and in threaded engagement with said threaded portion of said screw so that rotation of said screw will cause said slide tube to translate in said tubular shell altering said length of said screw actuator. 14. The vehicle transporter of claim 13 wherein said screw actuator further comprises a follower nut in threaded engagement with said screw and in slidable relative to said interior of said tubular shell. 15. The vehicle transporter of claim 13 wherein said screw actuator further comprises a motor including a frame attached to said tubular shell and a shaft rotatable in said frame and drivingly connected to rotate said screw. 16. The vehicle transporter of claim 13 wherein said threaded portion of said screw is arranged so that said threaded engagement of said nut and said screw is self-locking to prevent forces tending to translate said slide tube from causing rotation of said screw. 17. The vehicle transporter of claim 12 wherein said frame includes a substantially horizontal frame beam and connection of said tubular shell and said slide tube to said transporter define a line that is not normal to said frame beam when said actuator is of at least one length. 18. A vehicle transporter comprising: (a) a vehicular frame; (b) a first vehicle support member supported by said vehicular frame and selectively movable relative to said vehicular frame; and (c) a plurality of screw actuators, each comprising: (i) an elongate tubular shell comprising a wall defining an shell exterior and a shell interior, said tubular shell having a pivoting connection to at least one of said vehicular frame and said vehicle support member; (ii) a slide tube having a first end, said first end having a pivotal connection to the other of said vehicular frame and said vehicle support member; a second end; and a slide tube wall connecting said first end and said second end and defining a slide tube interior and a slide tube exterior, said slide tube exterior being arranged to slide within said shell interior; (iii) a guide in sliding engagement with said slide tube interior; (iv) a screw including a threaded portion, a first end rotatably supported for rotation of said screw in said shell interior, and a second end rotatably supported by said guide; (v) a nut restrained to said slide tube and in threaded engagement with said threaded portion of said screw so that rotation of said screw will cause said slide tube to translate in said tubular shell altering a dimension between said connection of said first end of said slide tube and said connection of said tubular shell causing said first vehicle support member to move relative to said vehicular frame; (vi) a follower nut in threaded engagement with said screw and slidably bearing on said shell interior; and (vi) a hydraulic motor having a frame attached to said tubular shell and a shaft selectively rotatable in said frame and drivingly connected to said screw. 19. The vehicle transporter of claim 18 further comprising: (a) a second vehicle support member pivotally attached at a first end to said first vehicle support member; and (b) another screw actuator having a first pivoting connection to said vehicular frame, a second pivoting connection to said second vehicle support member, and elongate members that slide longitudinally relative to each other in response to rotation of a screw to selectively vary a length between said first and said second connections causing said second vehicle support member to pivot about said first end. 20. The vehicle transporter of claim 18 further comprising: (a) a third vehicle support member slidably attached to said first vehicle support frame; and (b) an additional screw actuator having a first connection to said first vehicle support member, a second connection to said third vehicle support member, and elongate members that slide longitudinally relative to each other in response to rotation of a screw to selectively vary a length between said first and said second connections causing said third vehicle support member to translate relative to said first vehicle support member. 21. A screw actuator comprising: (a) a tubular shell connectible to a first member; said tubular shell comprising a wall defining an exterior and an interior; (b) a slide tube having a first end, a second end, and a slide tube wall connecting said first end and said second end and defining a slide tube interior and a slide tube exterior, said slide tube exterior being slidably arranged in said interior of said tubular shell, said slide tube connectible to a second member; (c) a guide in sliding engagement with said slide tube interior; (d) a screw having a threaded portion and a first end rotationally supported by said guide, said screw arranged for rotation in said interior of said tubular shell; and (e) a nut in threaded engagement with said threaded portion of said screw and constrained to translate with said slide tube so that rotation of said screw will cause said slide tube to translate in said tubular shell altering a length of said screw actuator. 22. The screw actuator of claim 21 further comprising a follower nut in threaded engagement with said screw and spaced apart from said nut. 23. The screw actuator of claim 22 further comprising an indicator of contact between said follower nut and at least one of said nut and said slide tube. 24. The screw actuator of claim 21 further comprising a motor including a frame connected to said tubular shell and a shaft rotatable in said frame and drivingly connected to rotate said screw. 25. The screw actuator of claim 21 wherein said threaded portion of said screw is arranged so that a force tending to displace said slide tube will not cause rotation of said screw. 26. The screw actuator of claim 21 wherein said threaded portion of said screw comprises an Acme thread having a lead angle not exceeding five degrees. 27. The screw actuator of claim 21 wherein at least one of said tubular shell and said slide tube is pivotally connectible, respectively, to one of said first member and said second member. 28. The screw actuator of claim 27 further comprising a follower nut in threaded engagement with said screw and spaced apart from said nut. 29. The screw actuator of claim 21 further comprising: (a) a hydraulic motor comprising a frame attached to said tubular shell, said frame including a fluid port, and a shaft rotatable in said frame and drivingly connected to rotate said screw, said shaft rotatable by pressurized fluid at said fluid port; and (b) a hydraulic valve attached to one of said tubular shell and said frame of said hydraulic motor and connected to selectively block a flow of fluid to said fluid port. 30. A vehicle transporter comprising: (a) a vehicular frame; (b) a vehicle support member movable relative to said vehicular frame; (c) a screw actuator pivotally connected to said vehicular frame and said vehicle support member and having first and second elongate members that slide longitudinally relative to each other in response to rotation of a screw so as to alter a length of said actuator causing said vehicle support member to move relative to said vehicular frame; and (d) a motor having a motor frame connected to said first elongate member of said screw actuator and movable in unison with said first elongate member and a motor shaft rotatable in said motor frame and drivingly connected to rotate said screw. 31. A screw actuator comprising: (a) a tubular shell movably connectible to a first member; said tubular shell comprising a wall defining an exterior and an interior; (b) a slide tube having a first end, a second end, and a slide tube wall connecting said first end and said second end and defining a slide tube interior and a slide tube exterior, said slide tube exterior being slidably arranged in said interior of said tubular shell, said slide tube connectible to a second member; (c) a screw arranged for rotation in said interior of said tubular shell; (d) a nut in threaded engagement with said screw and constrained to translate with said slide tube so that rotation of said screw will cause said slide tube to translate slidably in said tubular shell altering a length of said actuator; and (e) a motor having a motor frame attached to said tubular shell and movable in unison with said tubular shell, and a motor shaft rotatable in said motor frame and drivingly connected to rotate said screw. | CROSS-REFERENCE TO RELATED APPLICATIONS Not applicable. BACKGROUND OF THE INVENTION The present invention relates to vehicle transporters, such as trucks, trailers, and the like, that have vehicle support members movable relative to the frame of the transport vehicle and, more particularly, to a vehicle transporter having a vehicle support member movable by a screw actuator. Vehicle transporters are normally equipped with elongate vehicle support members to engage and support the wheels of the vehicles comprising the cargo. The vehicle support members may be fixed to the vehicular frame of the vehicle transporter, but are often movable relative to the vehicular frame to permit orienting the cargo vehicles so that the payload can be maximized and the height of the transporter reduced to satisfy legal requirements and to clear overpasses and other obstacles. The movable vehicle support members can also be positioned to form a surface over which cargo vehicles can be driven during loading and unloading. The movable vehicle support members are, typically, moved by means of elongate hydraulic cylinder assemblies connecting the vehicular frame and the vehicle support members. However, a significant drawback of such transporters is the time required to mechanically lock each hydraulic cylinder assembly in position when the transporter is loaded and unlock each cylinder assembly so that the associated vehicle support members can be repositioned during loading and unloading. Mechanical locking is important to maintain the position of a vehicle support member in the event that the hydraulic cylinder assembly does not continue to support the load due to a broken fluid supply line, seal failure, leakage, inadvertent control actuation, or some other reason. This task typically requires the manual insertion or removal of a pin at each of the hydraulic cylinder assemblies. Since a vehicle transporter may have 16 or more pairs of hydraulic cylinders, half of which are typically located on each side of the vehicle transporter's frame, correctly positioning the hydraulic cylinders and manually locking or unlocking each cylinder is very time consuming. Andre et al., U.S. Pat. No. 5,938,382, disclose the use of screw drives for positioning vehicle supporting members on an over-the-road vehicle transporter. Each vehicle supporting structure is supported by at least one pair of laterally spaced screw drives. The screw drives comprise a powered screw supported in tension from its upper end in a substantially vertical hollow post. Each screw is rotated by a hydraulic motor having a shaft attached to the bottom of the screw and a case attached to the transporter's frame. A nut, that is captive in the post, is displaced along the screw when the screw is rotated by a motor attached to the lower end of the screw. The cross-section of the post is a C-shaped channel and a portion of the nut projects through the gap in the channel section and is attached to a vehicle supporting member. The posts are fixed and, typically, substantially vertical to avoid side loads that might bend the screw or damage the motor bearings. The fixed, vertical posts complicate the connections to the vehicle supporting members which are often pivoted about one end to facilitate orienting the cargo vehicles to maximize the number carried by the transporter. In addition, the gap in the channel-shaped cross-section of the post exposes the screw and nut to the elements, including moisture and road salt, in the harsh over-the road environment. To synchronize rotation of motors powering a pair of laterally spaced screws and, therefore, the translation of the movable nuts supporting a vehicle support structure, the motors are hydraulically connected in series so that the exhaust of the first motor is the supply for the second motor. Each motor is connectable to the reservoir and to the pump supplying pressurized fluid. Each motor is also connected to its paired motor by a fluid line extending across the transporter's frame. In addition, the supply and exhaust ports of each motor of the pair must be cross connected, through a pair of relief valves, to the ports of other motor so that leakage does not prevent one of the actuators from moving through the full range of motion. While a series fluid connection roughly synchronizes the operation of a pair of fluid actuators, each actuator must exhaust exactly the volume that is required to supply the other actuator or some circuitry must be provided to account for the difference increasing the number of valves, supply lines, and connections in the fluid supply and control system. In the alternative, the paired hydraulic actuators can be connected in parallel. However, the movement of hydraulic actuators connected in parallel is not synchronized and the actuator experiencing the lowest pressure will move first and fastest. If the actuators are connected in parallel, a means must be provided to equalize the displacement of the actuators because differences in the internal construction of the actuators, friction or binding in the connections for the vehicle supporting structure, or side-to-side differences in the weight of the cargo vehicle commonly causes unequal displacement of the laterally spaced actuators of a pair of actuators supporting a vehicle supporting structure. What is desired, therefore, is a self-locking actuator that is well protected from the environment and conveniently connectable to the various movable and stationary members of the structure of a vehicle transporter. BRIEF DESCRITION OF THE DRAWINGS FIG. 1A is a simplified elevation view of a truck unit of an exemplary embodiment of a vehicle transporter. FIG. 1B is a simplified elevation view of a trailer unit of an exemplary embodiment of a vehicle transporter. FIG. 2 is a perspective view of a trailer unit of an exemplary embodiment of a vehicle transporter. FIG. 3 is a simplified elevation view of the truck unit of FIG. 1A and a portion of the trailer unit of FIG. 1B with an upper tier of vehicle support members positioned to form a ramp from the trailer unit to the truck unit. FIG. 4 is a simplified elevation view of a portion of the trailer unit of FIG. 1B with vehicle supporting members positioned to form a ramp from the ground to the upper tier of vehicle support members of the trailer unit. FIG. 5 is a side view of a partially extended first embodiment of an extendible screw actuator. FIG. 6 is a cut-away view of the extendible screw actuator of FIG. 5. FIG. 7 is a side view of a second embodiment of an extendible screw actuator. FIG. 8 is a cut-away view of the extendible screw actuator of FIG. 7. FIG. 9 is a partial cutaway, elevation view of a extendible vehicle support structure and a third embodiment of an extendible screw actuator viewed from the longitudinal centerline of the truck unit of a vehicle transporter. FIG. 10 is a simplified schematic of a first embodiment of a hydraulic system for a vehicle transporter incorporating decentralized controls for a plurality of actuators. FIG. 11 is a simplified schematic of an electrical system for controlling a hydraulic system including decentralized controls for a plurality of actuators. FIG. 12 is a simplified schematic of a second embodiment of a hydraulic system for a vehicle transporter incorporating decentralized controls for a plurality of actuators. DETAILED DESCRIPTION OF THE INVENTION Referring in detail to the drawings where similar parts of the invention are identified by like reference numerals, and, more particularly, to FIGS. 1A and 1B, an exemplary vehicle transporter 50 comprises, generally, a truck unit 52 and a trailer unit 54 connected by a hitch 56. The truck unit 52 and the trailer unit 54 are each adapted to carry a plurality of automobiles or other vehicles as cargo. Both the truck 52 and the trailer 54 include a plurality of comparable, transversely spaced, vehicle support members spaced apart to support the wheels of the vehicles carried as cargo by the transporter. The truck unit 52 is preferably capable of transporting four or five vehicles depending upon their size and the trailer unit 54 is preferably equipped to transport a larger number of vehicles. The truck unit 52 includes an elongate truck vehicular frame 58 with a plurality of posts 62, 64, 66, 68, 70 projecting upward along either side of the vehicular frame and interconnected at their tops by upper rails 72, 74. One or more cargo vehicles 76 can be supported on a lower tier of elongate vehicle support members 78 arranged along either side of the vehicular frame 58 and spaced to engage the wheels of the cargo vehicles. The vehicle support members 78 supporting the lower tier of vehicles may be fixed to the vehicular frame or movable relative to the frame. The wheels of an upper tier of cargo vehicles are supported by comparable vehicle support members extending along the edges of the truck unit 52 and elevated above the vehicle support members 78 supporting the lower tier of cargo. While a vehicle support member for the upper tier of vehicles may be fixed relative to the truck vehicular frame 52, typically at least one end of a vehicle support member is movable relative to the vehicular frame. The spaced vehicle support members supporting the upper tier of cargo are commonly connected at, at least, one end so that a pair of vehicle support members is movable as a vehicle support structure. For example, a forward or first upper tier vehicle support structure 80 of the truck unit 52, comprising a vehicle support member on each side of the truck unit, is pivotally attached at its forward end to vertical posts 60 extending upward from either side of the vehicular frame 58. The rearward end of the first upper tier vehicle support structure 80 is pivotally attached to a first end of a link 82 that has a second end pivotally attached to an elongate hydraulic actuator arranged inside of the hollow vertical post 70. Referring also to FIG. 9, second 84 and third 86 upper tier vehicle support structures of the truck unit 52 are attached at their forward ends by pivots 88 that are displaceable vertically relative to the truck's vehicular frame 58. The pivots 88 restrain movement of the vehicle support structures along the longitudinal axis of the truck unit 52 but permit the vehicle support structures 84, 86 to move vertically and rotate relative to the vehicular frame 58. The pivots 88 engage a vehicle support member of the respective vehicle support structure 84, 86 and an elongate hydraulic actuator located in the interior of the respective, hollow vertical post 64, 68 enables the pivot to be selectively raised or lowered and the vehicle supporting member to rotate about the pivot. The elongate hydraulic actuator may be a screw drive comprising a screw 804 suspended from a bearing block 854 by jam nuts 856 at the upper end and powered by a hydraulic motor (not illustrated) at the lower end. The pivot 88 includes a portion projecting through a slot in the post 64, 68 that is connected to a nut 802 in threaded engagement with the screw and slidable in the hollow post. When the screw is rotated, the nut 802 translates along the screw 802, raising or lowering the pivot 88. The ends of the second 84 and third 86 upper tier vehicle support structures nearer the rear of the truck unit 52 are each pivotally attached to a link 83 which is, in turn, pivotally attached to an elongate hydraulic actuator arranged in each of the respective vertical posts 62, 66. The pair of hydraulic actuators supporting a front or rear end of one of the second 84 and third 86 upper vehicle support structures may be extended or retracted to tilt the vehicle support structure. On the other hand, both of the pairs of actuators supporting a vehicle support structure may be extended or retracted to move the vehicle support structure vertically. Tilting the vehicle support structures permits a low profile portion, such as hood or trunk, of one vehicle to overlap a low profile portion a second vehicle in an adjacent position maximizing the number of vehicles in the cargo. By lowering and tilting the vehicles of the cargo after loading, the overall height of the transporter can be reduced to meet over-the-road legal requirements and provide clearance under bridges and other overhead obstructions. Loading and unloading may require raising the upper tier of vehicle support members to provide clearance for higher profile portions, such as the cabin, of the cargo vehicles of the lower tier. Tilting and displacing the vehicle support structures 80, 84, 86 permits the vehicle support members to be arranged as a continuous surface over which cargo vehicles can be driven during loading and unloading. Referring specifically to FIG. 1B and FIG. 2, the trailer unit 54 includes an elongate trailer vehicular frame 100 comprising, generally, transversely spaced, substantially horizontal frame beams 102 supported by a plurality of wheels 104 proximate the rear of the frame and the hitch 56 that connects the front of the trailer vehicular frame to the truck vehicular frame 58. The trailer unit 54 also includes transversely spaced vehicle support members 78 arranged along each side of trailer vehicular frame 100 to support the wheels of one or more vehicles in a lower tier of the cargo. While the vehicle support members 78 supporting the lower tier of vehicles may be fixed to the trailer's vehicular frame, in some cases the vehicle support members are movable relative to the frame. For example, a first lower tier vehicle support structure 108, including sections of vehicle support members 78, is pivotally and slidably attached to linear actuators within front 110 and rear 112 posts of a vertical frame 114 projecting upward at either side of the trailer vehicular frame 100. Extending and retracting actuators located inside the hollow front 110 and rear 112 posts permits the first lower tier vehicle support structure 108 to be raised to the level of the portions of the vehicle support members arranged over the wheels 104 of the trailer unit 54 to facilitate cargo loading and then lowered, as illustrated in FIG. 1B, to lower the profile of the cargo vehicle 116 and reduce the overall height of the trailer unit for travel. Referring to FIG. 4, extendible screw actuators 118, 120 are arranged to translate vehicle support member sections 122 at the rear of the trailer unit 54 to form slide out skids permitting cargo vehicles to be driven onto the elevated vehicle support members of the trailer unit. On the trailer unit 54, an upper tier of cargo vehicles is supported by an elevated, movable first upper tier vehicle support structure 124 and an elevated, movable second upper tier vehicle support structure 126. The adjacent ends of the first 124 and second 126 upper tier vehicle support structures, proximate the middle of the trailer 54, are connected to each other by a support structure pivot 128. A swing arm 130 is pivotally connected at one end to each of the vertical frames 114 at the side of the trailer vehicular frame 100 and pivotally connected at the second end to the support structure pivot 128 connecting the first 124 and second 126 upper tier vehicle support structures. An extendible, screw actuator 132 is pivotally connected to each of the swing arms 130 at one end and pivotally connected to the vehicular frame 100 at the second end. When the screw actuators 132 are extended, the support structure pivot 128 connecting the first 124 and second 126 upper tier vehicle support members will be moved upward and forward relative to the trailer vehicular frame 100 in an arc defined by the swing arms 130. On the other hand, when the screw actuators 132 are retracted, the support structure pivot 128 will move toward the rear and downward relative to the trailer vehicular frame 100. The ends of the first 124 and second 126 upper tier vehicle support structures of the trailer unit 54 distal to the support structure pivot 128 are also supported above the frame by pairs of laterally spaced, extendible screw actuators 136, 138. If the support structure pivot 128 is held stationary, extending or retracting a respective pair of actuators 136 or 138 at the distal end of a respective support structure 124, 126 will cause the support structure to tilt relative to the vehicular frame 100. With coordinated actuation of the three sets of screw actuators 132, 136, 138, supporting the first 124 and second 126 upper tier vehicle support structures, the vehicle support members can be positioned to form a ramp, as illustrated in FIG. 4, permitting cargo vehicles on the ground to be driven onto the upper tier vehicle support members. Appropriate extension or retraction of the screw actuators 132, 136, 138 can also be used to raise, lower, or tilt the first 124 and second 126 upper tier vehicle support structures to maximize the cargo capacity and minimize the height of the trailer unit 54. When the screw actuators 132, 136, 138 are extended to position the first 124 and second 126 upper tier vehicle support structures to form a ramp for loading and unloading cargo vehicles, the first and second support structures are displaced rearward by motion of the swing arms 130. As illustrated in FIG. 3, a pair of vehicle support members 140, slidably attached to the first upper tier vehicle support structure 124 of the trailer 54, can be extended by a pair of extendible screw actuators 142 to form a slide out ramp to bridge the gap between the first upper tier vehicle support structure of the trailer and the third upper tier vehicle support structure 86 of the truck unit 52 forming a continuous surface for cargo vehicles as they are driven from the ground at the rear of the trailer unit 54 to the first position vehicle support structure 80 at the front of the truck unit. Referring to FIGS. 5 and 6, the screw actuator 200 is a first embodiment of an extendible screw actuator, such as the actuators 132, 136, 138 supporting the vehicle support members 124 and 126. The screw actuator 200 typically includes a hollow tubular shell 202, having a wall defining an interior and an exterior. The tubular shell 202 is affixed to a mounting 204. The mounting 204 typically includes a bore 206 through which a pin can be inserted to pivotally connect the mounting to a structural member of the trailer, such as the vehicular frame 100, a swing arm 130 or one of the vehicle support members of one of the vehicle support structures, for example vehicle support structure 124. A hollow slide tube 208 having a wall 210 defining a tube interior and an exterior is slidably arranged in the interior of the hollow tubular shell 202. The slide tube 208 also typically has a cross bore 212 to receive a pin to connect the slide tube to another structural member of the vehicular frame, swing arm, or vehicle support member, as appropriate. The extendible actuator 200 is extended by sliding the slide tube 208 out of the tubular shell 202 increasing the length between the bores establishing connection to the appropriate structural members and retracted when the slide tube slides into the tubular shell. A first end of a screw 214 is supported for thrust and rotation by bearings 216 in the actuator mounting 204. The screw 214 projects along the co-extending centerlines of the tubular shell 202 and the slide tube 208. The distal end of the screw 214 is rotatably supported by a guide 216 that is slidably arranged in the interior of the slide tube 208 and secured by a collar 217. A nut 218, in threaded engagement with the screw 214, is retained in captive engagement at the inner end to the slide tube 208. The nut 218 is constrained against rotation and translates along the screw 214 when the screw is rotated and, as a result of the captive engagement with the slide tube, displaces the slide tube accordingly. Although other thread forms could be used, the screw and the nut typically include an Acme thread which has proportions making the thread desirable for power transmission. The Acme thread preferably has a lead angle less than five degrees preventing the load from back driving the nut 218 on the screw 214. This self-locking screw thread eliminates the need for a braking mechanism on the screw or manual locking pins to sustain the position of the vehicle supporting members after they have been positioned, reducing the time and effort required to load and unload the cargo. Supporting the screw 214 at both ends permits mounting the extendible screw actuator 200 vertically or at any angle to vertical, including horizontal, and substantially increases the ratio of the extended length the actuator to the retracted length by reducing bending and column loading on the screw. To alter the position of a vehicle support member, such as one of vehicle support structures, the screw 214 is rotated by a motor 220 having a case 222 attached to the actuator mounting 204 and a rotatable shaft 224 connected to drive the screw 214. The driving connection between the shaft 224 and the screw 214 may comprise a linked chain 226 connecting sprockets 228, 230 attached, respectively, to the motor shaft 224 and the screw 214; gears; or another torque transmitting mechanism. The motor 220 is, typically, a hydraulic motor. A hydraulic valve 232 is attached a manifold 233 affixed to the motor's case. The electrical solenoid controlled valve 232 selectively permits or blocks the flow of fluid through at least one motor port to control rotation of the motor 220. However, the motor 220 could be an electric motor or other type of motor capable of generating the torque necessary to rotate the screw 214. Mounting the motor 220 on the screw actuator 200 facilitates the pivoting of the actuator as it is extended and retracted. A follower nut 234 is threaded on the screw in spaced relation to the nut 218. The follower nut 234 is constrained against rotation and translates along the screw 214 when the screw is rotated. In the event that the nut 218 should fail, the slide tube 208 will retract into the tubular shell 202 until further movement is blocked by the follower nut. The follower nut 234 will support the vehicle support structure or other load until the actuator 200 can be repaired. A mark 209 on the slide tube 208 that is visible until the slide tube is fully retracted and at least one of the nut and the slide tube is in contact the follower nut 218 provides a visible indicator of the need to repair or replace the actuator. A second embodiment of the extendible screw actuator 300 is illustrated in FIGS. 7 and 8. The actuator 300 includes a hollow tubular shell 302 that is affixed to a mount 304. The mount 304 includes tapped holes 306 to receive screws 308. The round heads of the screws 308 provide a pivoting connection for a cooperating yoke 312, attachable to a member in the transporter structure. A second member is connectible to the actuator 300 by a pin engaging a cross bore 314 in a slide tube 316 that is arranged to slide in the interior of the tubular shell 302. The slide tube 316 is extended and retracted in the tubular shell 302 by the interaction of screw 320 and a nut 318, in threaded engagement with the screw and in captive engagement with the slide tube. The screw 320 is rotatably supported at one end by bearings 322 arranged in the mount 304 and at the other end by a guide 324 that is slidable in the interior of the slide tube 316. A locking nut 326 retains the guide 324 to the screw 320. The screw 320 is rotated by a hydraulic motor 328 that has a frame that bolted to the base of the mount 304 and a rotatable shaft 330 with an exterior spline that engages a cooperating interior spline in an aperture in the end of the screw 320. A hydraulic valve 332, attached to the mount 304, is connected to a fluid port in the motor 328 by passageways internal to the mount. The valve 332 can selectively block the flow of fluid to or from at least one port in the motor 328 to control rotation of the motor. A follower nut 334 is threaded onto the screw 320 in a spaced relationship to the nut 318. The follower nut 334 is constrained against rotation by pins 340 inserted in bores 342 and 344 in the nut 318 and the follower nut 334, respectively. If the threads of the nut 318 should fail, the slide tube 316 will retract into tubular shell 302 until it is supported by the follower nut 334. An indicator, such as a mark 336, on the slide tube 316 that is not visible when the slide tube is fully retracted and one of the slide tube and the nut 318 is in contact with the follower nut 334 indicates the need to repair or replace a damaged actuator. The vehicle support members of the second 84 and third 86 upper tier vehicle support structures of the truck unit 52 include extendible sections 87 to accommodate the varying wheelbases of the various vehicles comprising the cargo of the vehicle transporter 50. Referring to FIG. 9, the vehicle support structures 84, 86 comprise generally a pair of transversely spaced side rails 800 which support sections of the vehicle support members 78. A side rail 800 is arranged proximate to each side of the vehicular frame and movably attached to vertical posts extending upward from the vehicular frame 58. The forward end of the side rail 800 is attached to one of the vertical posts 64, 68 by a pivot 88. The pivot 88 is supported by carrier slidable inside the hollow post 64, 68 and vertically adjustable by movement of the carrier, for example, a nut 802 in threaded engagement with a powered screw 804 of a screw drive. The rearward end of the side rail 800 is supported by a linear actuator enclosed within the appropriate rear post 62, 66. The linear actuator is attached to the side rail 800 by a link 83 that is pivotally attached to the side rail 800 by a pin 806 and to the linear actuator by a pin 808. The side rail 800 comprises generally a third embodiment of the extendible screw actuator. The outer surface of the side rail 800 comprises a tubular shell 810 having a rectangular, C-shaped cross-section with a longitudinally extending slot in the vertical leg nearest the center of the vehicle. A front mount 812, including provisions for the pivot 88, and a rear mount 814, having an aperture for receiving the link pin 806, are attached to the tubular shell 810. A hollow slide tube 816 is slidably arranged in the interior of the hollow tubular shell 810. At one end, a screw 818 is supported for thrust and rotation about an axis generally co-extensive with the central axis of the slide tube 816 by bearings 820 arranged in a bearing mount 822 that is retained in the interior of the tubular shell 810 by screws 824. The second end of the screw 818 is rotationally supported by a guide 826 that is slidable in the interior of the slide tube 816 and secured by a locking nut 852. A nut 828, in threaded engagement with the screw 818 and constrained against rotation, is held captive in the interior of the slide tube 816 by retainers 830, 832. As determined by the direction of rotation, when the screw 818 is rotated the nut 828 translates along the screw pushing the slide tube 816 out of the tubular shell 810 or drawing the slide tube into the tubular shell. Sections 834 of a vehicle support member 78 comprise one leg, attached to the slide tube 816 and a slide tube extension 836 welded into the outboard end of the slide tube by hardware, including capscrews 838 that are aligned with the slot in the C-shaped cross-section of the tubular shell 810, and a second normal leg that projects horizontally from the slide tube toward the center of the transporter. The screw 818 is rotated by a hydraulic motor 840 having a case attached to a motor mount 842 retained in the forward end of the tubular shell 810 by screws 844. The motor 840 includes a rotatable shaft 846 that is coupled to the screw 818 by a coupling 848 having internal splines cooperating with external splines on the motor shaft and the screw. Rotation of the motor shaft 846 is controlled by a hydraulic valve 850 attached to a flange on the motor case. The hydraulic valve is typically actuated by a built-in electric solenoid and selectively permits or blocks the flow of hydraulic fluid to at least one fluid port of the motor. The vehicle transporter 50 includes a hydraulic supply and control system to provide and control the flow of pressurized fluid to the multiple pairs of laterally spaced actuators used to position support the various vehicle support members. A typical vehicle transporter may include 16 or more pairs of hydraulic actuators arranged along the sides of the transporter. Decentralizing the hydraulic controls, that is, locating the control valve for an actuator closer to the actuator than a control valve controlling another actuator or a control valve controlling the direction of motion of the actuator, and connecting the laterally spaced actuators in parallel permits the hydraulic supply and return conduits to be routed down each side of the vehicular frame of the transporter substantially reducing the number of conduits that must be routed through the frame and the number of potentially leaky connections. As a result, the cost of producing and operating a vehicle transporter can be substantially reduced while the performance is substantially enhanced. Referring to FIG. 10, a single pump hydraulic supply and control system 600 controls the flow of pressurized fluid to at least two pairs of actuators 602, 604 and 606, 608 used to position vehicle support members of a truck unit and at least two pairs of actuators 652, 654 and 656, 658 used to position vehicle support members of a trailer unit of an exemplary vehicle transporter. While, the hydraulic supply and control system schematically illustrated in FIG. 10 has been simplified for clarity of illustration, a typical vehicle transporter may include 16 or more pairs of hydraulic actuators arranged along the sides of the transporter and connected in parallel to the conduits 610, 612, 613 extending along the edges of the vehicular frame of the truck and 660, 661, 662 extending along the edges of the trailer. A pump 616 draws fluid from a reservoir 618 and supplies the fluid under pressure to a pressure conduit 617 connectable to the truck fluid conduits 610, 612, 613 and, through quick disconnect fittings 619, to the trailer supply conduits 660, 661, 662. The respective truck 610, 612, 613 and trailer 660, 661, 662 conduits are connectible to at least, two pairs of paired actuators, schematically illustrated, for example, as a pair of hydraulic cylinder assemblies 602, 604 and a pair of hydraulic motors 606, 608 of the truck unit. In a vehicle transporter, the individual actuators, for example cylinders 602 and 604, of a pair of actuators are typically spaced apart transversely at the sides of the vehicular frame and the pairs of actuators are located at different positions longitudinally along the vehicular frame of the truck or the trailer unit of the transporter. The flow of hydraulic fluid to each actuator of a pair of actuators, for examples, actuators 602 and 604 and actuators 606 and 608, is controlled by a respective two position, solenoid operated, actuator hydraulic control valve 622, 624, 626, 628 having a first position selectively blocking the flow of fluid to or from a first port 634 of the respective actuator and a second position selectively permitting fluid to flow between the respective actuator and the conduit 612, 613. Likewise, the actuators 652, 654, 656, 658 of the trailer unit are controlled by respective actuator hydraulic control valves 672, 674, 676, 678. The hydraulic actuator control valves, exemplified by valve 622, are relatively small and inexpensive and are mounted adjacent to the port 634 of the respective actuator, so that each control valve is closer to its respective actuator than an actuator control valve controlling another actuator or a hydraulic valve controlling the direction of movement of the actuator. Typically, as illustrated by example in FIG. 9, the actuator hydraulic control valve 850 is attached to the actuator at or immediately adjacent to one of the fluid ports eliminating a long fluid conduit and potentially leaking connections between the valve and the actuator. The direction of operation of the multiple hydraulic actuators, for example actuators 602, 604, 606, 608 of the truck unit, is controlled by a three position, four-way, solenoid operated, hydraulic, direction controller valve 614. The direction controller 614 includes a first valve position that blocks flow from the pump 616 and flow to or from the actuators through the conduits 610, 612, 613. A second valve position of the direction controller 614 directs the flow of pressurized fluid from the pump 616 to a pair of parallel fluid conduits 610 connectable to the first port 634 of the actuators 602, 604, 606, 608 through the respective actuator control valves 622, 624, 626, 628 and returns the exhaust flowing from a second port 636 of the respective actuators through the conduits 612, 613 to the reservoir 618. When shifted to a third valve position, the direction controller 614 directs the flow of pressurized fluid from the pump 616 to the second ports 636 of the respective actuators 602, 604, 606, 608 through the conduits 613 and allows any exhaust permitted to flow from the respective first ports 634 of the actuators by the respective actuator hydraulic control valves 622, 624, 626, 628 to return to the reservoir 618 through the parallel conduits 610. The direction of operation of the actuators 652, 654 656, 658 of the trailer unit is controlled in the same manner by the trailer direction control valve 664. A flow equalizer 644, 694 downstream of the respective truck and trailer direction controllers 614, 664 equalizes the flow of fluid in the parallel conduits 612, 613 and 660, 661, respectively. Adjustable relief valves 638, 640, 642, 690, 692 protect the pump 616, actuators, and actuator control valves from high pressures. A solenoid operated dump valve 696 selectively connects the output of the pump 616 to the reservoir 618. To actuate a pair of actuators independently of the other pairs of actuators, for example to extend the actuator pair 602, 604, the operator of the vehicle transporter starts a motor driving the pump 616; shifts the direction controller 614 to the second valve position, directing pressurized fluid from the pump to the parallel conduits 610, and shifts the respective actuator control valves 622, 624 to the open position permitting pressurized fluid to enter the shells of the actuators behind the pistons. As the pistons displace the rods of the actuators 602, 604, fluid is displaced through the respective second ports 636 of the actuators and returns to the reservoir 618 through the fluid conduits 612, 613. Referring to FIG. 12, in a second embodiment of the hydraulic supply and control system for the actuators of a vehicle transporter, a double pump 619 is utilized to provide equal flows to the actuators arranged along the two sides of the transporter. Like FIG. 11, the hydraulic supply and control system schematically illustrated in FIG. 12 has been simplified for clarity of illustration. The additional actuators of the typical vehicle transporter are connectable in parallel to the conduits 910, 911, 912, 913, 960, 961, 962, 963 extending along the edges of the vehicular frame of the truck and the trailer units, respectively. The double pump 916 draws fluid from a reservoir 918 and supplies the fluid under pressure to a pair of pressure conduits 917, 919 connectable to the truck fluid conduits 910, 911, 912, 913 and, through quick disconnect fittings 921, to the trailer supply conduits 960, 961, 962, 963. The respective truck 910, 911, 912, 913 and trailer 960, 961, 962, 963 conduits are connectible to at least, two pairs of paired actuators, schematically illustrated, for example, as a two pairs of hydraulic motors 902, 904, 606, 608 of the truck unit. In a vehicle transporter, the individual actuators, for example cylinders 602 and 604, of a pair of actuators are typically spaced apart transversely at the sides of the vehicular frame and the pairs of actuators are located at different positions longitudinally along the vehicular frame of the truck or the trailer unit of the transporter. The flow of hydraulic fluid from the conduits to each actuator of a pair of actuators, for examples, actuators 902 and 904, is controlled by a respective two position, solenoid operated, actuator hydraulic control valve 922, 924 having a first position selectively blocking the flow of fluid to or from a first port 934 of the respective actuator and a second position selectively permitting fluid to flow between the respective actuator and the conduit 911, 913. Likewise, the actuators 952, 954, 956, 958 of the trailer unit are controlled by respective actuator hydraulic control valves 972, 974, 976, 978. The direction of operation of the multiple hydraulic actuators on one side of the truck or trailer, for example actuators 902 and 906 of the truck unit, is controlled by a respective three position, four-way, solenoid operated, hydraulic, direction controller valve 915. The direction controller 915 includes a first valve position that blocks flow from the pump 916 through the pressure conduit 919 and connects the conduits on one side of the truck 911 and 912 to the reservoir 918. A second valve position of the direction controller 915 directs the flow of pressurized fluid from the pump 916 to the fluid conduit 912 connectable to first port 634 of the actuators 902, 906 on one side of the truck through the respective actuator control valves 922, 926 and returns the exhaust flowing from a second port 936 of the respective actuators through the conduit 911 to the reservoir 918. When shifted to the third valve position, the direction controller 915 directs the flow of pressurized fluid from the pump 916 to the second ports 936 of the respective actuators 902, 906 through the conduit 911 and allows any exhaust permitted to flow from the respective first ports 934 of the actuators by the respective actuator hydraulic control valves 922, 926 to return to the reservoir 918 through the conduits 911. An identical direction control valve 914 controls the direction of operation of the actuators 904, 908 on the second side of the truck unit by selectively connecting pressure from the pump 916 to the conduits 910, 913. Likewise, the direction of operation of the actuators 952, 956 and the actuators 954, 958 arrayed along the sides of the trailer is controlled by the direction control valves 965, 964 which selectively connect pressure and drain to the conduits 961, 962 and the conduits 960, 963. The adjustable relief valves 940, 942 protect the system from high pressures and the solenoid operated dump valves 995, 996 can selectively connect the output of the pump 616 to the reservoir 618. Referring to FIG. 11, the operation of the hydraulic supply and control system of the vehicle transporter is controlled electrically. Actuator control switches 702, 704 control respective pairs of actuator hydraulic control valves, for example actuator hydraulic control valves 622, 624 and 626, 628 of the truck unit and the direction controller 614 of the single pump embodiment of the hydraulic control system 600. When the operator is ready to reposition a vehicle support structure of the vehicle transporter, the pump start switch 706 is closed to start the pump motor 708. To extend the pair of actuators 602, 604, the operator moves the actuator control switch 702 to the raise position, energizing the raise solenoid 710 of the direction controller 614 and the solenoids 714, 716 of the respective pair of actuator hydraulic control valves 622, 626 for the transversely spaced pair of elongate hydraulic actuators. The energized raise solenoid 710 of the direction controller 614 shifts the valve to the second valve position directing pressurized through the parallel conduit 610. The energized solenoids 714, 716 of the actuator valves 622, 624 shifts the valves to their open positions, permitting fluid to flow into the actuators 602, 604 extending the rods of the actuators. To retract the actuators 602, 604, the operator moves the actuator control switch 702 to the lower position energizing the lower solenoid 712 of the direction controller 614 and the actuator control valve solenoids 714, 716 of the actuator control valves 622, 624. The direction controller 614 shifts to the third position and pressurized fluid is directed to the second port 636 of the actuators 602, 604. The energized actuator control valve solenoids 714, 716 shift the actuator control valves 622, 624 to the open position permitting fluid to flow out of the first port 634 and back to the reservoir 618 through the parallel conduits 610. Operating the actuator control switch 704 will produce comparable operation of the direction controller 614 and by energizing the solenoids 718, 720 of the actuator hydraulic control valves 626, 628 produce comparable movement of the respective actuators 606, 608. In the double pump hydraulic supply and control system 900, actuation of actuator switches 702, 704 energizes the solenoids of the two parallel direction control valves 915 and 914 of the truck unit and the appropriate actuator control valves solenoids 714, 716, 718, 720 controlling the actuator control valves 922, 924, 926, 928. Operation of the actuators of the trailer units is controlled in the same manner. Since the actuators, for example 602, 604, of each transversely spaced pair are connected in parallel, the actuator experiencing the lowest pressure will extend first and fastest. By way of examples, differences in the seals of the individual actuators, differences in the friction at the spaced-apart pivots of a vehicle supporting structure, binding due to uneven extension of actuators connected to a vehicle supporting structure, or side-to-side variation in the weight of a supported vehicle can cause a pressure differential in the paired actuators. The hydraulic supply and control system 600, 900 includes a displacement equalizer operably interposed between the direction controller 614 and the actuator control valves 622, 624, 626, 628 to permit the operator to equalize flow between the actuators of a pair of actuators, for example, actuators 602 and 604. If the operator selects the raise operation at the actuator control switch 702 the direction controller 710, and actuator control valve solenoids 714, 716 are energized as described above causing the actuators 602, 604 to extend. If the operator detects that a first actuator, for example actuator 602, controlled by the actuator control valve 622 that is operated by the actuator control valve solenoid 714, is moving faster than its paired second actuator 604, the operator can move a flow equalizer switch 726, schematically to the downward, to open the normally closed relay 728, de-energizing the solenoid 714 causing the spring loaded actuator control valve 622, to shift and block flow to the actuator 602. Since the solenoid 716 of the actuator control valve 624 remains energized, the actuator 604 will continue to extend. When the operator returns the flow equalizer switch 726 to the center position, the relay 728 will close, re-energizing the solenoid 714 causing fluid to flow again to both actuators 602, 604. On the other hand, if the solenoids 718, 720 have been actuated by the operator, moving the flow equalizer switch 726 schematically downward will cause the relay 728 to open deactivating solenoid 718. Moving the flow equalizer switch 726 schematically to upward, opens the normally closed relay 730 to deenergize either the solenoid 716 or the solenoid 720 blocking flow to the actuator. The flow equalizer switch 726 will interrupt the operation of any actuator on a respective side of the vehicular frame selected by the operator. In the double pump hydraulic supply and control system 900 displacement equalization can be accomplished in the same manner. In addition, since flow from the pump to each side of the truck or trailer unit flows through a unique passage, displacement could be equalized by selectively de-energizing the solenoids of the appropriate one of the direction control valves 914, 915 or 964, 965 or energizing the appropriate dump valve 995 or 996 to interrupt flow to one side of the transporter. The decentralized hydraulic controls provide flexible control of the multiple hydraulic actuators of the typical vehicle transporter while substantially reducing the cost of the transporter and the number of potential leak points in the hydraulic system. The self-locking screw actuators speed the loading and unloading of the vehicular transporter by eliminating the manual insertion or removal of locking pins at each of the actuators supporting the vehicle support members. The screw actuator can be conveniently connected to the structure of the vehicle transporter and used in any orientation facilitating its use to position vehicle supporting members that translate and tilt. Enclosing the screw and nut of the provides good protection from dirt and moisture in the over-the-road environment. The detailed description, above, sets forth numerous specific details to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid obscuring the present invention. All the references cited herein are incorporated by reference. The terms and expressions that have been employed in the foregoing specification are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims that follow. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to vehicle transporters, such as trucks, trailers, and the like, that have vehicle support members movable relative to the frame of the transport vehicle and, more particularly, to a vehicle transporter having a vehicle support member movable by a screw actuator. Vehicle transporters are normally equipped with elongate vehicle support members to engage and support the wheels of the vehicles comprising the cargo. The vehicle support members may be fixed to the vehicular frame of the vehicle transporter, but are often movable relative to the vehicular frame to permit orienting the cargo vehicles so that the payload can be maximized and the height of the transporter reduced to satisfy legal requirements and to clear overpasses and other obstacles. The movable vehicle support members can also be positioned to form a surface over which cargo vehicles can be driven during loading and unloading. The movable vehicle support members are, typically, moved by means of elongate hydraulic cylinder assemblies connecting the vehicular frame and the vehicle support members. However, a significant drawback of such transporters is the time required to mechanically lock each hydraulic cylinder assembly in position when the transporter is loaded and unlock each cylinder assembly so that the associated vehicle support members can be repositioned during loading and unloading. Mechanical locking is important to maintain the position of a vehicle support member in the event that the hydraulic cylinder assembly does not continue to support the load due to a broken fluid supply line, seal failure, leakage, inadvertent control actuation, or some other reason. This task typically requires the manual insertion or removal of a pin at each of the hydraulic cylinder assemblies. Since a vehicle transporter may have 16 or more pairs of hydraulic cylinders, half of which are typically located on each side of the vehicle transporter's frame, correctly positioning the hydraulic cylinders and manually locking or unlocking each cylinder is very time consuming. Andre et al., U.S. Pat. No. 5,938,382, disclose the use of screw drives for positioning vehicle supporting members on an over-the-road vehicle transporter. Each vehicle supporting structure is supported by at least one pair of laterally spaced screw drives. The screw drives comprise a powered screw supported in tension from its upper end in a substantially vertical hollow post. Each screw is rotated by a hydraulic motor having a shaft attached to the bottom of the screw and a case attached to the transporter's frame. A nut, that is captive in the post, is displaced along the screw when the screw is rotated by a motor attached to the lower end of the screw. The cross-section of the post is a C-shaped channel and a portion of the nut projects through the gap in the channel section and is attached to a vehicle supporting member. The posts are fixed and, typically, substantially vertical to avoid side loads that might bend the screw or damage the motor bearings. The fixed, vertical posts complicate the connections to the vehicle supporting members which are often pivoted about one end to facilitate orienting the cargo vehicles to maximize the number carried by the transporter. In addition, the gap in the channel-shaped cross-section of the post exposes the screw and nut to the elements, including moisture and road salt, in the harsh over-the road environment. To synchronize rotation of motors powering a pair of laterally spaced screws and, therefore, the translation of the movable nuts supporting a vehicle support structure, the motors are hydraulically connected in series so that the exhaust of the first motor is the supply for the second motor. Each motor is connectable to the reservoir and to the pump supplying pressurized fluid. Each motor is also connected to its paired motor by a fluid line extending across the transporter's frame. In addition, the supply and exhaust ports of each motor of the pair must be cross connected, through a pair of relief valves, to the ports of other motor so that leakage does not prevent one of the actuators from moving through the full range of motion. While a series fluid connection roughly synchronizes the operation of a pair of fluid actuators, each actuator must exhaust exactly the volume that is required to supply the other actuator or some circuitry must be provided to account for the difference increasing the number of valves, supply lines, and connections in the fluid supply and control system. In the alternative, the paired hydraulic actuators can be connected in parallel. However, the movement of hydraulic actuators connected in parallel is not synchronized and the actuator experiencing the lowest pressure will move first and fastest. If the actuators are connected in parallel, a means must be provided to equalize the displacement of the actuators because differences in the internal construction of the actuators, friction or binding in the connections for the vehicle supporting structure, or side-to-side differences in the weight of the cargo vehicle commonly causes unequal displacement of the laterally spaced actuators of a pair of actuators supporting a vehicle supporting structure. What is desired, therefore, is a self-locking actuator that is well protected from the environment and conveniently connectable to the various movable and stationary members of the structure of a vehicle transporter. | 20040329 | 20060411 | 20050929 | 85008.0 | 2 | GUTMAN, HILARY L | VEHICLE TRANSPORTER WITH SCREW ACTUATORS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,852 | ACCEPTED | Apparatus for monitoring a system with time in space and method therefor | Apparatus and method for monitoring a system in which a fluid flows and which is characterized by a change in the system with time in space. A preselected place in the system is monitored to collect data at two or more time points correlated to a system event. The data is indicative of a system parameter that varies with time as a function of at least two variables related to system wash-in and wash-out behavior. A calibration map is made on a calculated basis with each pixel or voxel representative of a color hue indicative of wash-out behavior and a color intensity indicative of wash-in behavior. The calibration map serves as a criteria for selecting the time points. Software and a data processing system are provided to develop a color coded output map. The calibration map, the color coded output map and image of the preselected place are also novel implementations. | 1. A method for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising the steps of: A. monitoring a preselected area or volume of a system in which a fluid flows, and which is characterized by a change in the system with time in space to collect data at a plurality of time points correlated to a system event; B. said collected data being indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. processing said collected data by a. dividing the preselected area or volume of the system into a grid; b. determining for each grid location at preselected time points a value of said system parameter; c. determining for each grid location based on said time points preselected from the plurality of time points an intensity function that is correlated with initial rate of wash-in behavior; d. colorizing and producing an output of each said grid point with respect to color hue/color intensity on the basis of i. color hue as determined by a plurality of wash-out behaviors; and ii. color intensity as determined by said intensity function; D. preparing a color hue/color intensity coded map from the outputs of said grid points representative of the system in two or three dimensions from the output of said colorized grid points. 2. The method of claim 1 wherein the time points are preselected on the basis of a predetermined criteria, the first time point being just before the monitoring step, the second time point being temporally after the first time point, and the third time point being temporally after the second time point. 3. The method of claim 1 including the further step of storing the outputs of the colored grid points. 4. The method of claim 1 including the further step of storing the coded map. 5. The method of claim 4 including the further step of digitally storing the map. 6. The method of claim 1 including the further steps of creating an image based on the intensity values of the grid points at each said preselected time point. 7. The method of claim 1 including the further step of displaying the color hue/color intensity coded map. 8. The method of claim 7 wherein a monitor is provided to display the coded map. 9. The method of claim 1 including the further step printing the coded map. 10. The method of claim 1 including the further step of fixing the coded map in a computer readable storage medium. 11. The method of claim 1 wherein the system event is the introduction into the fluid of a tracer medium. 12. The method of claim 1 wherein the system is human tissue and the fluid is blood. 13. The method of claim 1 wherein the system is breast tissue and the system event is the introduction of a contrast medium into the blood. 14. A method for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising the steps of: A. monitoring a preselected area or volume of a system in which a fluid flows, and which is characterized by a change in the system with time in space to collect data at a plurality of time points correlated to a system event; B. said collected data being values indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. processing said collected data by a. dividing the preselected area or volume of the system into a multitude of discrete locations; b. determining for each discrete location, at preselected time points, a value of said system parameter; c. determining for each discrete location, based on said time points preselected from the plurality of time points, an intensity function that is correlated with wash-in behavior; d. determining for each location, at said preselected time points, the wash-out behavior e. colorizing each discrete location with respect to color hue for wash-out/color intensity for wash-in correlated with the value of the parameter of the system for said discrete location; and e. producing an output for each colorized discrete location; and D. preparing at least one color hue/color intensity coded map from the outputs of the colorized discrete locations of the system in two or three dimensions. 15. The method of claim 14 including the further step of choosing three time points as the preselected time points on the basis of a predetermined criteria, the first time point being before the monitoring step, the second time point being temporally after the first time point, and the third time point being temporally after the second time point. 16. The method of claim 14 including the further step of storing the outputs of the colored grid points. 17. The method of claim 14 including the further step of storing the coded map. 18. The method of claim 17 including the further step of digitally storing the map. 19. The method of claim 14 including the further steps of creating an image based on the intensity values of the grid points at each said preselected time point. 20. The method of claim 14 including the further step of displaying the color hue/color intensity coded map. 21. The method of claim 20 wherein the coded map is displayed on a monitor. 22. The method of claim 14 including the further step printing the coded map. 23. The method of claim 14 including the further step of fixing the coded map in a computer readable storage medium. 24. The method of claim 14 wherein the system event is the introduction of a tracer medium into the fluid. 25. The method of claim 14 wherein the system is human tissue and the fluid is blood. 26. The method of claim 25 wherein the system is breast tissue and the system event is the introduction of a contrast medium into the blood. 27. A method for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising the steps of: A monitoring a preselected area or volume of a system in which a fluid flows and which is characterized by a change in the system with time in space to collect data at a plurality of preselected time points correlated to a system event; B said collected data being in the form of signal intensities indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C choosing three of the preselected time points on the basis of a predetermined criteria such that a first time point is before the monitoring step, a second time point is temporally after the first time point on the basis of the predetermined criteria, and the third time point is temporally after the second time point on the basis of the predetermined criteria; D processing said collected data of signal intensities by a. dividing the preselected area or volume of the system into a grid; b. determining for each grid location at each of said chosen second and third time points a value of said signal intensity; c. determining a color function on the basis of the relationship of the signal intensities at said chosen second and third time points; d. applying the color function to each said grid point to colorize and produce an output of each grid point with respect to color hue of one of a plurality of colors on the basis of a plurality of distinct wash-out behaviors as determined from the signal intensities at the said grid point at said chosen second and third time points; and E. preparing from the outputs of said colorized grid points a color hue coded map representative of said system parameter to be measured in two or three dimensions. 28. The method for monitoring a system according to claim 27 wherein three colors are employed for three distinct wash-out behaviors. 29. The method for monitoring a system according to claim 28 wherein the colors are red, green and blue. 30. The method for monitoring a system according to claim 27 in which the monitoring step is carried our using magnetic resonance. 31. The method for monitoring a system according to claim 27 including the further step of establishing thresholds for said three distinct wash-out behaviors. 32. The method for monitoring a system according to claim 27 wherein the monitoring step is carried out using tracer modulated MRI. 33. The method for monitoring a system according to claim 27 wherein said system parameter varies in time as a function of at least one variable. 34. The method for monitoring a system according to claim 33 wherein the at least one variables is one of microvascular permeability times surface area and fraction of extracellular volume. 35. The method for monitoring a system according to claim 27 wherein the predetermined criteria includes color distribution. 36. The method of claim 27 including the further step of storing the outputs of the colored grid points. 37. The method of claim 27 including the further step of storing the coded map. 38. The method of claim 37 including the further step of digitally storing the map. 39. The method of claim 27 including the further steps of creating an image based on the intensity values of the grid points at each said preselected time point. 40. The method of claim 27 including the further step of displaying the color hue coded map. 41. The method of claim 40 wherein a monitor is provided to display the coded map. 42. The method of claim 27 including the further step printing the coded map. 43. The method of claim 27 including the further step of fixing the coded map in a computer readable storage medium. 44. The method of claim 27 wherein the system event is the introduction of a tracer medium into the fluid. 45. The method of claim 27 wherein the system is human tissue and the fluid is blood. 46. The method of claim 27 wherein the system is breast tissue and the system event is the introduction of a contrast medium into the blood. 47. A method for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising the steps of: A. monitoring a preselected area or volume of a system in which a fluid flows and which is characterized by a change in the system with time in space to collect data at a plurality of preselected time points correlated to a system event; B. said collected data being in the form of signal intensities indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. choosing three of the preselected time points on the basis of a predetermined criteria such that a first time point is before the monitoring step, a second time point is temporally after the first time point on the basis of the predetermined criteria, and the third time point is temporally after the second time point on the basis of the predetermined criteria; D. processing said collected data of signal intensities by a. dividing the preselected area or volume of the system into a grid; b. determining for each grid location at said chosen first and second time points a value of said signal intensity c. producing an output of each grid point with respect to color intensity of one of a plurality of colors on the basis of a plurality of distinct wash-in behaviors as determined from the signal intensities at the said grid point at said chosen first and second time points; and E. preparing from said output of said grid points a color intensity coded map correlated with said system parameter to be measured in two or three dimensions. 48. The method for monitoring a system according to claim 47 wherein three colors are employed for three distinct wash-in behaviors. 49. The method for monitoring a system according to claim 48 wherein the colors are red, green and blue. 50. The method for monitoring a system according to claim 47 in which the monitoring step is carried our using magnetic resonance. 51. The method for monitoring a system according to claim 48 including the further step of establishing thresholds for said three distinct wash-in behaviors. 52. The method for monitoring a system according to claim 47 wherein the monitoring step is carried out using tracer modulated MRI. 53. The method for monitoring a system according to claim 47 wherein said system parameter varies in time as a function of at least one variable. 54. The method for monitoring a system according to claim 53 wherein the at least one variable is one of microvascular permeability times surface area and fraction of extracellular volume. 55. The method for monitoring a system according to claim 47 wherein the predetermined criteria includes color distribution. 56. The method of claim 47 including the further step of storing the outputs of the colored grid points. 57. The method of claim 47 including the further step of storing the coded map. 58. The method of claim 47 including the further step of digitally storing the map. 59. The method of claim 47 including the further steps of creating an image based on the intensity values of the grid points. 60. The method of claim 47 including the further step of displaying the color hue/color intensity coded map. 61. The method of claim 60 wherein a monitor is provided to display the coded map. 62. The method of claim 47 including the further step printing the coded map. 63. The method of claim 47 including the further step of fixing the coded map in a computer readable storage medium. 64. The method of claim 47 wherein the system event is the introduction into the fluid of a tracer medium. 65. The method of claim 47 wherein the system is human tissue and the fluid is blood. 66. The method of claim 65 wherein the system is breast tissue and the system event is the introduction of a contrast medium into the blood. 67. A method for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising the steps of: A. monitoring a preselected area or volume of a system in which a fluid flows and which is characterized by a change in the system with time in space to collect data at a plurality of preselected time points correlated to a system event; B. said collected data being in the form of signal intensities indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. choosing three of the preselected time points on the basis of a predetermined criteria such that a first time point is before the monitoring step, a second time point is temporally after the first time point on the basis of the predetermined criteria, and the third time point is temporally after the second time point on the basis of the predetermined criteria; D. processing said collected data of signal intensities by a. dividing the preselected area or volume of the system into a grid; b. determining for each grid location at said chosen first, second and third time points a value of said signal intensity; c. colorizing and producing an output of each grid point with respect to color hue/color intensity of one of a plurality of colors on the basis of a plurality of distinct wash-out behaviors and wash-in behaviors, respectively, as determined from the signal intensities at the said grid point at said chosen first, second and third time points; E. preparing from the outputs of said colorized grid points a color hue/color intensity coded map representative of said system parameter to be measured in two or three dimensions. 68. The method for monitoring a system according to claim 67 wherein three colors are employed for three distinct wash-out behaviors. 69. The method for monitoring a system according to claim 68 wherein the colors are red, green and blue. 70. The method for monitoring a system according to claim 67 in which the monitoring step is carried our using magnetic resonance. 71. The method for monitoring a system according to claim 67 including the further step of establishing thresholds for said three distinct wash-out behaviors. 72. The method for monitoring a system according to claim 67 wherein the monitoring step is carried out using tracer modulated MRI. 73. The method for monitoring a system according to claim 67 wherein said system parameter varies in time as a function of at least one variable. 74. The method for monitoring a system according to claim 73 wherein the at least one variable is one of microvascular permeability times surface area and fraction of extracellular volume. 75. The method for monitoring a system according to claim 67 wherein the predetermined criteria includes color distribution. 76. The method of claim 67 including the further step of storing the outputs of the colored grid points. 77. The method of claim 67 including the further step of storing the coded map. 78. The method of claim 77 including the further step of digitally storing the map. 79. The method of claim 67 including the further steps of creating an image based on the intensity values of the grid points at said preselected time points. 80. The method of claim 67 including the further step of displaying the color hue/color intensity coded map. 81. The method of claim 80 wherein the coded map is displayed on a monitor. 82. The method of claim 67 including the further step printing the coded map. 83. The method of claim 67 including the further step of fixing the coded map in a computer readable storage medium. 84. The method of claim 67 wherein the system event is the introduction of a tracer medium into the fluid. 85. The method of claim 67 wherein the system is human tissue and the fluid is blood. 86. The method of claim 85 wherein the system is breast tissue and the system event is the introduction of a contrast medium into the blood. 87. A color coded map for use in evaluating a selected place in a system in which a fluid flows, and which is characterized by a change in the system with time in space as a function of a system parameter related to system wash-in behavior and wash-out behavior at two preselected time intervals after a system event, said map depicting in two or three dimensions an image of the system in a plurality of colors, and wherein the discrete elements of the image have been coded by a color function related to system behavior at the two preselected time points to have a color hue of one of said plurality of colors indicative of the system wash-out behavior. 88. A color coded map as recited in claim 87 in which the system comprises human tissue. 89. A color coded map as recited in claim 88 in which the system comprises human breast tissue. 90. A color coded map as recited in claim 88 in which the system comprises two breasts. 91. A color coded map as recited in claim 87 in which the system event is defined by injection of a tracer into the fluid. 92. A color coded map for use in evaluating a selected place in a system in which a fluid flows, and which is characterized by a change in the system with time in space as a function of a system parameter related to system wash-in behavior and wash-out behavior at two preselected time intervals after a system event, said map depicting in two or three dimensions an image of the system in a plurality of colors, and wherein the discrete elements of the image have been coded by an intensity function related to system behavior before the system event and the first of the two selected time points to have a color intensity indicative of the system wash-in behavior. 93. A color coded map as recited in claim 92 in which the system comprises human tissue. 94. A color coded map as recited in claim 92 in which the system comprises human breast tissue. 95. A color coded map as recited in claim 92 in which the system comprises two breasts. 96. A color coded map as recited in claim 92 in which the system event is defined by injection of a tracer into the fluid. 97. A color coded map for use in evaluating a selected place in a system in which a fluid flows, and which is characterized by a change in the system with time in space as a function of a system parameter related to system wash-in behavior and wash-out behavior at two preselected time intervals after a system event, said map depicting in two or three dimensions an image of the system in a plurality of colors, and wherein the discrete elements of the image have been coded by a color function related to system behavior at the two preselected time points to have a color hue of one of said plurality of colors indicative of the system wash-out behavior and have been coded by an intensity function related to system behavior at the system event and the first of the two selected time points to have a color intensity indicative of the system wash-in behavior. 98. A color coded map as recited in claim 97 in which the system comprises human tissue. 99. A color coded map as recited in claim 98 in which the system comprises human breast tissue. 100. A color coded map as recited in claim 99 in which the system comprises two breasts. 101. A color coded map as recited in claim 97 in which the system event is defined by injection of a tracer into the fluid. 102. A color coded map for use in evaluating a lesion in the breast of a subject body in which blood flows and in which a contrast agent has been injected into the blood and which is characterized by a change in the concentration of the contrast agent in the breast with time in space as a function of the contrast agent wash-in and wash-out behavior at two time intervals after injection of the contrast agent, said map depicting in two or three dimensions an image correlated with the said behavior, and wherein the discrete elements of the image have been color coded by a color function to have a color hue of one of a plurality of colors indicative of the contrast agent wash-out behavior and have been coded by an intensity function to have a color intensity indicative of the contrast agent wash-in behavior. 103. The color coded map of claim 102 wherein said behaviors are determined by two variables, K and v, wherein K defines microvascular permeability and v defines the fraction of extracellular volume which estimates the amount of free space in the breast. 104. Apparatus for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising: A. a monitor for monitoring a preselected area or volume of a system in which a fluid flows and which is characterized by a change in the system with time in space to collect data at a plurality of preselected time points correlated to a system event; B. said collected data being in the form of signal intensities indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. a processor for processing said collected data of signal intensities by a. dividing the preselected area or volume of the system into a grid; b. selecting three of the preselected time points on the basis of a predetermined criteria such that a first time point is before the monitoring step, a second time point is temporally after the first time point on the basis of the predetermined criteria, and the third time point is temporally after the second time point on the basis of the predetermined criteria; c. determining for each grid location at said selected time points values of said signal intensity; d. colorizing and producing an output of each grid point with respect to color hue of one of a plurality of colors on the basis of a plurality of distinct wash-out behaviors and a color function determined from the signal intensities at the said grid point for the said selected preselected time points; D. a generator for generating from the outputs of said colorized grid points a color hue coded map representative of said system parameter to be measured in two or three dimensions. 105. Apparatus according to claim 104 wherein a selector is provided to derive the color function from the signal intensities at the second and third time points. 106. Apparatus for monitoring a system in which a fluid flows, and which is characterized by a change in the system with time in space comprising: A. a monitor for monitoring a preselected area or volume of a system in which a fluid flows and which is characterized by a change in the system with time in space to collect data at a plurality of preselected time points correlated to a system event; B. a collector to collect said collected data in the form of signal intensities indicative of a system parameter to be measured that varies with time as a function of system wash-in behavior and system wash-out behavior; C. a processor for processing said collected data of signal intensities by a. dividing the preselected area or volume of the system into a grid; b. selecting three of the preselected time points on the basis of a predetermined criteria such that a first time point is before the monitoring step, a second time point is temporally after the first time point on the basis of the predetermined criteria, and the third time point is temporally after the second time point on the basis of the predetermined criteria; c. determining for each grid location at said selected time points values of said signal intensity; d. colorizing and producing an output of each grid point with respect to color intensity on the basis of a plurality of distinct wash-in behaviors and an intensity function determined from the signal intensities at the said grid point based on said selected preselected time points; D. a generator for generating from the outputs of said colorized grid points a color intensity coded map representative of said system parameter to be measured in two or three dimensions. 107. Apparatus according to claim 106 wherein the color function is derived from the signal intensities at the first and second time points. 108. Apparatus for monitoring by magnetic resonance imaging (MRI) a breast of a subject body in which blood flows and in which a contrast agent has been injected into the blood and which is characterized by a change in the concentration of the contrast agent in the breast with time in space comprising: (a) a monitor for monitoring an event in the breast for collecting data indicative of MRI signal intensity of the breast that varies with time as a function of contrast agent wash-in and wash-out behavior; (b) data processor responsive to the monitor for receiving the collected data and processing same including; (1) a divider for dividing the space a grid; (2) a determinator for determining for each grid location a calculated value and intensity function indicative of the wash-in of the contrast agent related to the monitored MRI signal intensity for each time point; (3) a colorizor for coloring all grid locations one of a plurality of colors based on a color function indicative of wash-out behavior of the contrast agent; (4) an arranger for arranging all grid locations for all time points into a composite to develop a color coded map of the grid with each grid location having a color hue/color intensity correlated to the function of contrast agent wash-in and wash-out behavior. 109. Apparatus for monitoring by magnetic resonance imaging (MRI) a breast of a subject body in which blood flows and in which a contrast agent has been injected into the blood and which is characterized by a change in the concentration of the contrast agent in the breast with time in space comprising: (a) a monitor for monitoring an event in the breast for collecting data indicative of MRI signal intensity of the breast that varies with time as a function of contrast agent wash-out behavior; (b) data processor responsive to the monitor for receiving the collected data and processing same including; (1) a divider for dividing the space a grid; (2) a determinator for determining for each grid location a value indicative of the wash-out of the contrast agent related to the monitored MRI signal intensity for two selected time points and providing an output; (3) a colorizor responsive to the output of the determinator for coloring all grid locations one of a plurality of colors based on a color function indicative of wash-out behavior of the contrast agent; (5) an arranger for arranging all grid locations for all time points into a composite to develop a color coded map of the grid with each grid location having a color hue correlated to the function of contrast agent wash-out behavior. 110. Apparatus for monitoring by magnetic resonance imaging (MRI) a breast of a subject body in which blood flows and in which a contrast agent has been injected into the blood and which is characterized by a change in the concentration of the contrast agent in the breast with time in space comprising: (a) a monitor for monitoring an event in the breast for collecting data indicative of MRI signal intensity of the breast that varies with time as a function of contrast agent wash-in and wash-out behavior; (b) data processor responsive to the monitor for receiving the collected data and processing same including; (1) a divider for dividing the space a grid; (2) a determinator for determining for each grid location a value and intensity function indicative of the wash-in of the contrast agent related to the monitored MRI signal intensity for each time point; (3) a colorizor for coloring all grid locations one of a plurality of colors based on a color function indicative of wash-out behavior of the contrast agent; (5) an arranger for arranging all grid locations for all time points into a composite to develop a color coded map of the grid with each grid location having a color intensity correlated to the function of contrast agent wash-in behavior. 111. Software for use with a computer having a memory, an input device for generating device event signals and a display, the software comprising a computer usable medium having computer readable program code thereon including: first program logic for dividing into a grid a system in which fluid flows and which is characterized by a change in the system with time in space correlated to a wash-in and wash-out behavior of the system; second program logic responsive to device event signals for determining an intensity function of each grid location related to wash-in behavior; third program logic to color all grid locations based on a predetermined color function correlated with wash-out behavior; and fourth program logic responsive to the second and third program logic for developing a color coded map of the grid with each grid location correlated to a color hue related to wash-out behavior, and correlated to a color intensity as determined by said intensity function related to wash-in behavior. 112. Software as in claim 109 further including fifth program logic responsive to the fourth program logic for displaying the color coded map on a display. 113. Software for use with a computer having a memory, an input device for generating device event signals and a display, the software comprising a computer usable medium having computer readable program code thereon including: first program logic for dividing into a grid a system in which fluid flows and which is characterized by a change in the system with time in space correlated to a wash-in and wash-out behavior of the system; second program logic to color all grid locations based on a predetermined color function correlated with wash-out behavior; and third program logic responsive to the second program logic for developing a color coded map of the grid with each grid location correlated to a color hue related to wash-out behavior. 114. Software for use with a computer having a memory, an input device for generating device event signals and a display, the software comprising a computer usable medium having computer readable program code thereon including: first program logic for dividing into a grid a space defined by two variables correlated to a wash-in and wash-out behavior of a system in which fluid flows which is characterized by a change in the system with time in space; second program logic responsive to device event signals for determining an intensity function of each grid location related to wash-in behavior; third program logic to color all grid locations based on a predetermined color function correlated with wash-out behavior; and fourth program logic responsive to the second and third program logic for developing a color coded map of the grid with each grid location correlated to a color intensity related to wash-in behavior. 115. Software for use with a computer having a memory, an input device for generating device event signals and a display, the software comprising a computer usable medium having computer readable program code thereon including: first program logic for dividing into a grid a space defined by at least one variable correlated to a wash-in and wash-out behavior of a system in which fluid flows which is characterized by a change in the system with time in space; second program logic responsive to device event signals for determining an intensity function of each grid location related to wash-in behavior; third program logic to color all grid locations; and fourth program logic responsive to the second and third program logic for developing a color coded map of the grid with each grid location correlated to one of a color and a color intensity as determined by said intensity function related to wash-in behavior and said coloring of all grid locations, respectively. 116. Data processing system for producing a color coded map for evaluating the output of a monitored system in which a fluid flows and which is characterized by a change in the monitored system with time in space with respect to wash-in and wash-out and wherein the monitoring occurs at a preselected location comprising: (a) computer processor for processing data; (b) storage means for storing data on a storage medium; (c) means for initializing the storage medium; (d) a first processor controller for dividing the space into a grid; (e) a second processor controller for determining for each grid location a signal intensity at each of a plurality of preselected time points; (f) a third processor controller for coloring all grid locations one of a plurality of colors based on a color function correlated with the determined signal intensities and with monitored system wash-out behavior; and (g) a fourth processor controller for arranging all grid locations for all time points into a color coded map of the grid with each grid location correlated to color hue with respect to wash-out and with color intensity as determined by an intensity function derived from the signal intensities related to wash-in. 117. Data processing system according to claim 116 including a fourth processor controller for determining the maximum of the signal intensity of the grid locations and normalizing all grid locations with reference to the maximum. 118. Data processing system for producing a color coded map for evaluating the output of a monitored system in which a fluid flows and which is characterized by a change in the monitored system with time in space with respect to wash-in and wash-out and wherein the monitoring occurs at a preselected location comprising: (a) computer processor for processing data; (b) storage means for storing data on a storage medium; (c) means for initializing the storage medium; (d) a first processor controller for dividing the space into a grid; (e) a second processor controller for determining for each grid location a signal intensity at each of a plurality of preselected time points; (f) a third processor controller for coloring all grid locations one of a plurality of colors based on a color function correlated with the signal intensities and with monitored system wash-out behavior; and (h) a fifth processor controller for arranging all grid locations for all time points into a color coded map of the grid with each grid location correlated to color hue with respect to wash-out. 119. Data processing system for producing a color coded map for evaluating the output of a monitored system in which a fluid flows and which is characterized by a change in the monitored system with time in space with respect to wash-in and wash-out and wherein the monitoring occurs at a preselected location comprising: (a) computer processor for processing data; (b) storage means for storing data on a storage medium; (c) means for initializing the storage medium; (d) a first processor controller for dividing the space into a grid; (e) a second processor controller for determining for each grid location a signal intensity of the parameter at each of a plurality of preselected time points; (f) a third processor controller for coloring all grid locations one of a plurality of colors; and (h) a fourth processor controller for arranging all grid locations for all time points into a color coded map of the grid with each grid location correlated to color intensity as determined by an intensity function derived from the signal intensities related to wash-in. | RELATED APPLICATIONS This application is a Continuation Application of Ser. No. 10/342,509, filed Jan. 15, 2003, which is a Divisional application of Ser. No. 09/843,283, filed Apr. 26, 2001, now U.S. Pat. No. 6,553,327, which is a Continuation-in-part of Ser. No. 09/101,708, filed Sep. 16, 1998, now U.S. Pat. No. 6,353,803, which is a 371 of PCT/US97/00801 filed Jan. 21, 1997. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to apparatus for monitoring a system with time in space and method therefor and more particularly relates to novel apparatus such as a unique MRI machine, a novel irrigation apparatus for testing the effectiveness of an irrigation system, a novel testing apparatus for determining the efficiency of a heating and/or cooling system, and the like, for testing or controlling a system in which fluid flows and where in the system fluid either dissipates in part or requires regeneration. 2. Description of the Prior Art Presently apparatuses are known for monitoring testing or measuring a system in which a fluid that is flowing or substances in the fluid will dissipate in part as it traverses the system or will require regeneration. For example, MRI machines are used today to create images with or without administration of a tracer-contrast agent. Customarily, the machine is controlled to take a series of images at discrete time intervals and the images are then dynamically analyzed to obtain an output result. For example, dynamic studies of contrast enhancement in breast tumors have demonstrated that the rate of change in signal intensity is an important parameter for the distinction of breast masses, leading to pharmacokinetic studies. However, it is known that as a result of tumor heterogeneity, there are significant local variations in the time evolution of contrast enhancement, and, therefore, maintaining high spatial resolution in both the recording and analysis steps is very important. In a standard clinical MRI of the breast, it is difficult to achieve high spatial resolution and also maintain high temporal resolution. In most dynamic studies performed previously, the emphasis was on high temporal resolution (at the expense of spatial resolution) monitoring the equilibration in the intravascular space and early diffusion into the extracellular space of the tissue. As a consequence, in standard MRI machines the output results are sometimes inconclusive. The foregoing is also characteristic of other systems in which a fluid flows or a component thereof dissipates in part or requires regeneration, such as, for example, an irrigation system, a heating and cooling system and the like. SUMMARY OF THE INVENTION Accordingly, the object of the present invention is to provide an apparatus or a machine, and a correlated method, for monitoring a system, in which a fluid is flowing, with time in space, which will provide more conclusive results regarding system anomalies or system efficiency. The present invention relates to an apparatus for monitoring a system with time in space. The system can be physical, chemical, biological, physiological, environmental, clinical or any other system in part or in whole, the system evolving with time over space in a certain way. The apparatus of the present invention can function on the basis of one, two, three or higher dimensions. The type and extent of spatial resolution and the number of time points and their spacing, that the apparatus selects, depend on the system and can be varied with a lower limit for the number of time points of two. For example, it can be used for processing time dependent data of radiologic examinations such as MRI, ultra-sonography, X-ray tomography or conventional X-ray, or Nuclear medicine for obtaining diagnosis, prognosis and therapy follow up of tumors or any other pathological disorders. It can be utilized for processing monitoring or controlling environmental data of water irrigation. It can be used to analyze data that will permit determination of leafing areas in pipes. It can be used to analyze data obtained in the food, cosmetic and other industries which involve mixture and solution preparations and determination of their homogeneity. It can be also used to assess the efficiency of heating and/or cooling systems. There are numerous phenomena that evolve over space with time in a way that can be treated according to the present invention by utilizing a novel approach which is termed herein as by wash-in and wash-out behavior. The wash-in and wash-out are terms that are used symbolically to describe a change in one direction (wash-in) and the reverse change (wash-out) which may not be true reversal but can be any pathway that induces a change. Specifically flow of fluid in a system where the fluid or fluid component dissipates or needs to be regenerated, is described according to the invention as wash-in and washout. For any wash-in/wash-out situation, it is possible to describe n numbers of patterns of wash-out, when n can range from 1 to any integral number, 2, 3, 4 etc., on the basis of m time points, when m can range from 2 to any integral number of specific time points in the time evolution of the process. The definition of wash-out is not strict and a wash-in can become a wash-out and vice versa. For each kind of system, the apparatus of the present invention provides means for monitoring, controlling or regulating the system by providing means for setting time points and other optimal parameters of the system. This setting uses a novel calibration map based on a physical model which describes the evolution with time in an approximate or rigorous manner. These calibration maps serve also to interpret quantitatively the final color hue/color intensity coded maps obtained as one of the products of the apparatus. One particular use of the novel apparatus is for contrast enhanced MRI data in order to obtain products that facilitate specific diagnosis of cancer. The time of start of contrast administration is time point t0 and then two post contrast time points t1 and t2 are utilized. These post contrast times are selected by constructing calibration maps based on modeling the kinetics of contrast enhancement that relates the wash-in/wash-out rates to two pathophysiological parameters: microvascular permeability times surface area (termed in short, microvascular permeability and represented by the letter K) and fraction of extracellular volume represented by v. The calibration map is constructed by the apparatus. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the novel apparatus of the present invention for monitoring a system with time in space; FIG. 2 is a block diagram of the details of the selecting means of the apparatus in FIG. 1 for setting the parameters for data collection; FIG. 3 is a block diagram of the details showing the colorize function C of the selecting means of the apparatus of FIG. 1; FIGS. 4a and 4b are a flow diagram of the selecting means of the apparatus of FIG. 1 illustrating the setting of the parameters for data collection; FIGS. 5a and 5b are a flow diagram of the selecting means showing the novel apparatus selecting means used as a novel MRI apparatus for collection of MRI images. FIG. 6 is a block diagram of the apparatus of FIG. 1 showing in detail the control and effect means of the apparatus for controlling and effecting data collection on a system; FIG. 7 is a block diagram of the apparatus as applied to MRI and shows the details of the control and effect means of the apparatus for controlling and effecting MRI data collection on a subject; FIG. 8 is a block diagram of the apparatus of FIG. 1 showing details of the processing means of the apparatus for processing the collected data; FIG. 9 is a flow diagram of the apparatus of FIG. 1 showing details of the processing means of the apparatus for processing data collected in two dimensions; FIG. 10 is a flow diagram of the apparatus of FIG. 1 showing the details of the processing means used for MRI for processing images collected from a subject; FIG. 11 is a block diagram of the apparatus of FIG. 1 showing the details of the analysis means of the apparatus for analyzing the processed data; FIG. 12 is a block diagram of the apparatus of FIG. 1 showing the details of the analysis means used for MRI for analyzing 3TP images; FIG. 13 is a graph showing the pattern of slow wash-out/slow wash-in and slow wash-out/fast wash-in for the three time points to, t1 and t2 and with data values I(t0), I(t1), I(t2); FIG. 14 is a graph like FIG. 13 showing the pattern of moderate wash-out/slow wash-in and of moderate wash-out/fast-wash-in; FIG. 15 is a graph like FIG. 13 showing the pattern of fast wash-out/slow washin and of fast wash-out/fast-wash-in; FIG. 16 is a schematic illustration of a typical calibration map as used in the novel apparatus for MRI. FIGS. 17(a), (b) and (c) show, respectively, (a) MLO mammographic projection of a 49 yo woman does not show 15 mm cancer which was palpable and diagnosed by in-office FNA as infiltrating ductal cancer. (b) Subtraction sagital MRI (0 minute (pre-contrast) image subtracted from 2 minute image shows ring-enhancing, spiculated malignancy in the anterior breast (arrow). Posteriorly, a small intramammary lymph note also enhances, but has a characteristic morphology, including fatty hilus (arrowhead). (c) 3TP parametric similar to that of 1b, but overlay of colored pixels is superimposed on MRI image by 3TP software based on a physiological model (described in text). Bright red indicates high probability for malignancy and this lesion was prospectively given a score of 5 (highly suspicious for malignancy). (d) Calibration map corresponding to patient shown in 1a. Color hue (red, green, blue) is based on differences in signal intensity between the second and third images of the three image 3TP image set. Color intensity is based on the difference in SI between the first and second images of the image set. As described in the text, areas of high vessel permeability×surface area and low extravascular volume fraction (EVF), typical of malignancy, will be coded as bright red. For optimal discrimination of benign and malignant lesions, the imaging parameters are chosen to approximately divide the calibration map into equal areas of red, green and blue. FIGS. 18(a) and (b) show, respectively, (a) MLO mammographic projection showing an ovoid focal lesion along the inferior mid breast (arrow) in a 69 yo woman. Pathological diagnosis, via excisional biopsy, was benign breast tissue. (b) 3TP sagital MRI parametric image shows virtually all dark blue pixels indicating a lesion with low values of vessel permeability×surface area and extravascular space—indicators of benignity. The prospective 3TP diagnosis was benign (suspicion level 2) FIGS. 19(a), (b) and (c) show, respectively, (a) MLO mammographic projection showing an area of ill-defined density and architectural distortion (arrow) in a 64 yo woman. Diagnosis, via excisional biopsy, was infiltrating ductal cancer. (b) Subtraction MRI (image at 0 minutes (pre-Gd contrast) subtracted from image at time 6 minutes) showing an irregular area of enhancement corresponding to the mammographic lesion. (c) Top three images are magnified views from adjacent slices of the central portion of the 3TP parametric image, calculated using 0, 2 and 6 minute MR images. The results show a visually indeterminate number of red pixels. The bottom three images are these same image locations, but 3TP images were recalculated using 0, 4 and 8 minute MR images. There is a shift toward an increasing number of red pixels, indicating malignancy to be more probable than benignancy. The prospective 3TP diagnosis was malignant, at suspicion level 4. FIG. 20 shows a ROC curve derived from 3TP data in which lesion location was supplied to the researcher, but no other clinical information was supplied. The researcher was then asked to supply a number from 1 to 5 indicating probability for malignancy or benignity. FIGS. 21(a), (b) and (c) show, respectively, (a) Optical close-up of mammographic magnification CC view—66 yo woman with cluster of microcalcifications in the superior mid breast. Pathological diagnosis was DCIS, low to intermediate grade. (b) Optical close-up of subtraction sagital MRI image—6 minutes after injection of Gadodiamide. Small irregular focus of enhancement (arrow) corresponds to cluster of microcalcifications. (c) Optical close-up of sagital 3TP image shows an area of predominantly bright green pixels thought to be benign (score=2). A total of three out of eight DCIS lesions were misdiagnosed as benign by the 3TP method. An area of future investigation is to determine whether there is a specific pattern for DCIS that will allow increased accuracy of diagnosis. FIGS. 22(a), (b) and (c) show, respectively, (a) Ultrasound examination of a mammographically occult palpable lesion in a 45 yo woman showing a gently lobulated mass, without acoustic shadowing, typically of fibroadenoma, which was confirmed by ultrasound-guided FNA. (b) Subtraction MIP MRI, 6 minutes after Gadodiamide injection, shows that the fibroadenoma confirmed by ultrasound is the largest of multiple enhancing smaller lesions. At the workstation, many of these smaller lesions showed an enhancement profile similar to that of the larger, palpable and sonographically confirmed lesion. In clinical practice evaluation of the multiple other enhancing lesions by manual placement of an ROI is impractical. Though internal septations are said to be an important MRI sign of fibroadenoma, they were not noted in this patient. (c) 3TP parametric image shows predominantly central bright green and peripheral blue pixels, consistent with a benign lesion (score=2). The 3TP parametric image showed no other suspicious lesions, however due to the multiplicity of similar lesions, the patient is simply being followed. Confirmation of multiple benign lesions will be assumed if no malignancy is diagnosed after two years of mammographic follow-up. FIGS. 23(a), (b) and (c) show, respectively, (a) Optical close-up of mammography (MLO projection) in a 44 yo woman showed a spiculated mass (straight arrow). An unexpected, mammographically occult, 2nd lesion was detected at the location indicated by the curved arrow, as a result of this patient volunteering for the 3TP clinical trial. Pathological diagnosis in both cases was infiltrating ductal cancer. (b) 3TP parametric sagital plane image of lesion suspected to be malignant by mammography. High predominance of bright red pixels indicates high value of the product of vascular permeability×surface area, and low extravascular volume fraction, indicating high probability of malignancy (score=5). (c) 3TP parametric image of a second adjacent sagital slice showing a second site very suspicious for malignancy (score 5). The radiologist discussed the scan with the surgeon and both sites were biopsied at the time of surgery confirming unsuspected multifocal malignancy. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a block diagram of an apparatus for monitoring a system with time in space which embodies the present invention. This apparatus includes selecting means 1 for setting the time points for data collection, and for setting the parameters of the portions of the apparatus used for data collection, and for processing a colorized calibration map for analysis of processed data that relates variables of the system to unique wash-out/wash-in behaviors which use color hue and color intensity for coding these behaviors. The selecting means is linked to a storage means 2 for storage the selected times, parameters and calibration map. The storage means 2 is linked to a control and effect means 3 for controlling the time and parameters of data collection determined by the selecting means 1 and for effecting the data collection. The means for effecting the data collection 3 are known in the art for which the apparatus will be used. The control and effect means 3 is linked to a storage means 4 for storing the data collected with time in space. The storage means 4 is linked to a processing means 5 for processing the stored collected data according to a novel unique wash-out/wash-in scheme which uses color hue and color intensity and which is programmed into the processing means 5. The processing means 5 is also linked to storage 2 to receive as part of its input parameters and values set in 1. The processing means 5 is linked to a storage means 6 for storing the processed data. The storage 6 is linked to analysis means 7 for analyzing the processed data. This means 7 is also linked to storage 2 for analyzing the processed data on the basis of the stored calibration map. All the means can operate sequentially using all storage means, part of the storage means or none. Instead of a storage means, a direct output to input link between blocks 1 to 3 or blocks 3 to 5 or blocks 5 to 7 can exist. The portions of the apparatus need not function all at the same time nor at the same location. Referring now to FIG. 2, there is shown a more detailed block diagram of the selected means, shown in block 1 of FIG. 1. The function of the selecting means is to select time points for data collection, parameters of data collection and for producing a novel calibration map that relates washout/wash-in characteristics coded in color hue/color intensity to variables of the specific system being monitored. The inputs of the program are blocks 10, 11, 12 and 13 and include the minimum and maximum values for variables of the system being monitored (block 10), input of constant parameters used for data collection (block 11), parameters used for data collection that can be varied (block 12) and three time points selected initially as an intuitive guess from general knowledge of the system as the starting point of an iterative procedure (block 13). The input of block 10 enables the apparatus to divide the system space defined by the variables into a grid, in block 14. For 1 variable, each grid point is a unit length. For 2 variables, each grid point defines a pixel, for 3 variables each grid point defines a volume (voxel). The grid developed in block 14 and the inputs of blocks 11, 12 and 13 serve to determine in block 15, for each grid point, a value for the parameter to be measured at preselected times termed 1(t0), I(t1) and I(t2), respectively. This determination or calculation uses an equation specific to the particular system being monitored that can estimate exactly or approximately the change with time in the value of the parameter to be measured for each set of variables of the system. Such equations are well known to those skilled in the art for particular systems. The values of I(t0) and I(t1) calculated in block 15 are used to determine or calculate in block 16, for each grid point, an intensity function according to the equation I ( t1 ) - I ( t0 ) [ I ( t0 ) ] ( t0 - t1 ) . This intensity function represents a wash-in characteristic of initial-rate of wash-in. Then in block 17, by a conventional loop, the grid point with a maximum intensity function is determined and is then outputted to block 18 as maximum intensity. In block 18, all other intensity functions in the remaining grid points are normalized in reference to the maximum intensity. Next, the apparatus in block 19 colorizes each grid point according to the program shown in FIG. 3. Referring to FIG. 3, function C, which determines the pattern of wash-out/color hue, is calculated or determined in blocks 22 and 23 in terms of I(t1) and I(t2), for each grid point, and a wash-out pattern/color hue is chosen according to: C = I ( t1 ) - I ( t2 ) I ( t1 ) . FIGS. 13, 14 and 15 describe systematically the principles of choosing a wash-out pattern which is coded in color hue and of choosing wash in initial rate (apparent initial rate) coded in color intensity. The first pattern (FIG. 13) is the slow wash-out pattern defined by I(t1)<I(t2) and is determined by I ( t2 ) - I ( t1 ) I ( t1 ) ≥ 0.1 . This pattern is for example coded with the color red. If the intensity function = I ( t1 ) - I ( t0 ) [ I ( t0 ) ] ( t1 - t0 ) , which is a measure of the apparent initial rate of wash-in, has a high value for a slow wash-out pattern, than the red color will be bright reflecting fast wash-in (FIG. 13). If the intensity function has a low value for a slow wash-out pattern than the red color will be dark reflecting slow wash-in (FIG. 13). The second pattern is the moderate wash-out pattern (FIG. 14) defined by I(t1)≈I(t2) is determined by - 0.1 < I ( t2 ) - I ( t1 ) I ( t1 ) < 0.1 . This pattern is, for example, coded with the color green. As in the red case, if the intensity function has a high value for this moderate pattern, then the green color will be bright (FIG. 14). If, however, the intensity function has a low value, the green color will be dark (FIG. 14). The third pattern (FIG. 15) is the fast washout pattern defined by I(t1)>I(t2) and is determined by I ( t2 ) - I ( t1 ) I ( ti ) ≤ 0.1 . This pattern is coded for example blue. Again if the intensity function is high, namely, wash-in apparent initial rate fast, the color blue will be bright (FIG. 15). If, however, the intensity function is low, the color blue will be dark (FIG. 15). Thus, for each pattern of wash-out coded by a color hue, there can be defined a wash-in rate which relates to the intensity function which determines color intensity. The separation between different wash-in rates depends on the range of color intensities chosen. Referring again to FIG. 2, in block 20 the apparatus, in the final output for the selected t0, t1 and t2 and for the selected system parameters, assigns to each grid point that defines values of the variables of the system a color hue and a color intensity. The colorized and intensity normalized grid points collectively are termed a “calibration map”. If the composite calibration map for the selected t0, t1, t2 and for the selected system parameters is satisfactory as will be explained in detail hereafter, the program ends and sends the output to storage in block 2 (FIG. 1) or directly to block 3 (FIG. 1). If the calibration map is not satisfactory, the apparatus makes an appropriate adjustment of the three time points, for example, by incrementing t1 and t2 and inputs into block 13. Alternatively, the apparatus can increment new values for parameters of the system and/or of the measurement, as preselected, and input into block 12. Also, both time points and these parameters can be changed. The steps in the program are repeated using the original inputs of blocks 10 and 11 and going from blocks 14 to 20. This iteration (block 21 in FIG. 2) can be repeated until a satisfactory calibration map is obtained for a set of preselected times and parameters. In the definition of the intensity function in block 16 (FIG. 2) and the definition of the pattern of wash-out/color hue function C in blocks 22 and 23 (FIG. 3) it is assumed that I(t1)>I(t0). In cases where I(t1) is negative but the absolute value of /I(t1)/ is higher than I(t0) the definitions hold for the absolute values. The choices for coloring function C in block 23 (FIG. 3) are not limited to the specific examples of C<−0.1, −0.1<_C<0.1 and C>—0.1, but any other fraction (such as 0.05 or 0.2) can be used to define C depending on the system. i. Referring now to FIG. 4, there is shown a flow diagram (steps or blocks) for setting the parameters for data collection and creating a calibration map. This flow diagram is written for a monitored parameter that varies with time as a function of two variables of the system assigned here with the letters K and v. For each grid point in a 2 dimensional grid of K and v, a pixel of dimension of 0.01 units of K and 0.01 units of v is defined in steps or blocks 38, 40, 53 and 55. The program starts in block 30 and gets inputs of the time points, t0, t1 and t2, system and measurement parameters and the range of K and the range of v between their min. and max. values in block 31. The program starts from pixel (K min, v min) in block 32 to calculate I(t0), I(t1), I(t2) in block 33 using an approximate or exact equation correlated to the system being monitored, as is known, that estimates how the parameter monitored with time I(t) depends on K and v, and on other system parameters. The determined or calculated I(t1) and I(t0) are used to calculate for each pixel Intensity (K, v) as shown in block 34, which represent wash-in initial rate. The program is then searching whether the pixel has max. Intensity (blocks 35 to 40) and proceeds through all the pixels in a loop mode returning to block 33 and going again through the steps 34 to block 40 until it reaches the pixel with maximum K and maximum v. Through this loop, the pixel with max. intensity is identified and intensity is calculated for all pixels (K, v). Now, the program proceeds to calculate for each pixel starting from pixel (K min, v min) block 43 a normalized intensity, block 44 normalized relative to the max. intensity. The pixel with max. intensity is assigned with a maximum value for intensity N. N can be 1, 2, 3 or any number such as, 8, 64, 256 (computer numbers), etc. depending on the demands of the system. Then, the program calculates the wash-out pattern for each pixel starting from pixel (K min, v min) until it reaches pixel (K max, v max) and codes with color hue each pattern as shown in blocks 45 to 54. Now, all pixels have a color hue and a normalized color intensity. This produces in the output a calibration map of K, v in block 56 for the selected t0, t1, t2 and system and measurement parameters. If the calibration map is not satisfactory e.g. excessively slanted toward one color hue, new time points, or new system or measurement parameter values, or all are adjusted in the direction to correct the calibration map and bring it to a more satisfactory balance from a color distribution standpoint. The program goes through all the steps in the flow diagram again using the new inputs until a satisfactory calibration map is obtained, which sets the selected time points and system parameters. What will be a satisfactory calibration map depends on the system and will be apparent to one skilled in the art. For most systems a satisfactory map will have about a third of the pixels red, a third green and a third blue. A specific example of a flow diagram for setting the parameters for tracer modulated NM, termed also contrast enhanced MRI, is shown in FIG. 5. The MRI signal is the monitored parameter that is changing with time as a result of administrating a tracer, termed also contrast agent. The input parameter in step 6 includes the three time points t0, t1 t2. These time points are obtained initially by experience in step 87 and are subjected to an iterative process until the best three time points are obtained. Other inputs are the tracer-dose and the MRI parameters that define how the NM signal is recorded. Both the tracer dose and MRI parameters can be constant, or can be optimized by the iterative process in step 87. The input also includes pharmacokinetics parameters that define the tracer change with time in the blood, and max. and min. values for the two variables K and v that define pathophysiological characteristics of the system, namely, a subject body. The variable K defines microvascular permeability which estimates the capacity of blood vessels to leak out the tracer. The variable v defines the fraction of extracellular volume which estimates the amount of free space in a tissue. The steps 62 to 85 in this flow diagram follow the steps 32-54 in FIG. 4. In this flow diagram the maximum intensity is assigned in step 74 to have the value of 256. The output in step 86 consists of a calibration map of the two variables K and v ranging between K min, v min to K max, v max for a specific set of time points and the other inputs. Each pixel in this map with specific K, v values has a color hue and a color intensity. A satisfactory calibration map is defined by reaching a certain distribution of the colors or of the colors and color intensities. For example, a satisfactory map can be a map that divides the K-v plan or plane, or volume between the three colors to approximately three equal areas, namely, approximately a third of the pixels in the calibration map are red, a third are green and a third are blue. Shown in FIG. 16 is a typical calibration map according to the present invention. The map was created based on the equations of contrast enhancement as known in the art, for the variables microvascular permeability K and fraction of extracellular volume v. The map is constructed as an expected pattern (e.g., color and color intensity) for any three or more selected time points. More explicitly, and with reference to FIG. 16, a three-dimensional representation in a two-dimensional drawing is used. FIG. 16 shows the time points for humans using a gradient echo and a tracer dose of 0.08 mmol/kg, with the time points: t0=0, t1=4 and t2=12 min. These time points were selected in order to discriminate between e.g., fibroadenoma and carcinoma. The isotherms represent regions of the same intensity in each pattern, e.g., same initial rate of wash-in. One dimension is microvascular permeability K ranging between values of interest (for example, 0.00 min−1 to 0.3 min−1. The second dimension is fraction of extracellular volume v ranging between 0.1 to 1 and the third dimension, normalized intensity is actually the intensity of each color (for example, any value between 0 to 256 intensities). This calibration map serves to determine optimal preset time points to, t1 and t2 and other parameters such as dose. For different systems it is possible to select different optimal time points. The calibration map also serves to interpret the output of the processing means of the apparatus, which for the specific example of MRI is a 3TP image, defined subsequently in the description. It is clear that if the three time points are chosen to be very close together the calibration map will show only a slow wash-out behavior, namely, the red pattern according to the above example will predominate. On the other hand, if the last point is chosen very far in time, the calibration map will be dominated by fast wash-out, namely, dominated by blue. The suitable 3 time points for a specific system are selected by having all three colors distributed in the most revealing way, namely, in the calibration map about one third of the area is occupied by each color. Flow Diagrams similar to the flow diagram in FIG. 5 exist for other specific systems. At the final output, a satisfactory calibration map of the variables for an optimal set of t0, t1, t2 and other inputs is always obtained. The time points and parameters are set at block 1 (FIG. 1) and are used by the control and effect means 3 to control and effect the data collection (FIG. 1). Referring now to FIG. 6, there is shown a detailed block diagram for controlling and effecting data collection. The input in blocks 90, 91 can be directly obtained from the storage 2 (FIG. 1) or from block 1 (FIG. 1). The measurements in blocks 92, 95 and 97, are performed by means specific for each system. Such means are known in each art. There must be control of times of tracer administration and of measure so that t0, t1 and t2 of the input are accurately controlled. The injection or administration of tracer in block 94 into the system can be performed in any known way. The timing of the tracer administration is fixed to start at t0 and should end usually, but not necessarily before t1, preferably close to t0. The data collected in blocks 92, 95 and 97 are transferred to processing means 5 (FIG. 1) either directly from block 3 (FIG. 1) or from storage 4 (FIG. 1). A specific example of a block diagram of a control and effect means for controlling and effecting the data collection, as part of a modified MRI. apparatus or machine for tracer modulated MRI, is shown in FIG. 7. The control and effect means shown in the block diagram of FIG. 7 receives as an input in block 120 the time points t0, t1 and t2 set by the selecting means in block 1 in FIG. 1, and described in detail for this specific example in the flow diagram 1 of FIG. 4. The other inputs relate to the MRI parameters and to the dose of the tracer and the pharmacokinetic parameters of the tracer that is injected into the blood of the subject. The MRI parameters and the dose of tracer are set by the selecting means in block 1 of FIG. 1, and are described in detail for tracer modulated MRI in the flow diagram of FIG. 4. Next, the apparatus, in block 121 in FIG. 7 records an image of a defined area or a defined volume in the system, namely a body, by means known in this art. The recording parameters are those set by the selecting means 1 in FIG. 1 and inputted into block 12 FIG. 7. The image is then stored in block 122 and a tracer, termed also a contrast agent, is administered at time t0 into the body in block 123 by any known way. This administration is timed to start at t0 for a duration that ends preferably, but not necessarily, close to time point t0 and before recording at time t1. After the administration of tracer, the apparatus, in block 124, at time t1 records an image of the same area or volume as was recorded in block 121 in the same body using the same NM parameters as in block 121. This image is stored in block 125. Next, at time t2, the apparatus, records another image of the same area or volume in the same body, using the same NIRI parameters as in block 121, and then stores this image in the storage of block 127. Referring now to FIG. 8 there is shown a more detailed block diagram of processing means shown in block 5 of FIG. 1. The inputs shown in block 100 of FIG. 8 are the time points to, t1 and t2 set in block 1 of FIG. 1 and used in block 3 of FIG. 1. Another input shown in block 101 of FIG. 8 includes the data collected in block 3 of FIG. 1. These data can be directly transferred from block 3 of FIG. 1 or from the storage in block 4 in FIG. 1. The data in block 101 of FIG. 8 for each spatial unit are presented by three data values obtained at three different times. The first data value for each spatial unit, is termed I(t0) and is obtained before administration of the tracer. The tracer and/or third is administered at time point to. Thus, the first data value is measured before time point t0 but as close to this time point as possible. The second data value for each spatial unit is obtained at time point t1 and is termed I(t1). The third data value for each spatial unit is obtained at time point t2 and is termed I(t2). Another input in block 101 in FIG. 8 is max Intensity. The max Intensity value is part of the output of the selected means as shown in block 20 in FIG. 2. From the data I(t0), I(t1) and the time points t0, t1 the normalized intensity is then determined in block 102 for each spatial unit. The normalized intensity is given by the equation [ I ( t1 ) - I ( t0 ) ] xN [ I ( t0 ) ] ( t1 - t0 ) x ( Max Intensity ) . I(t0), I(t1) and Max Intensity have been inputted in block 101. N is an integer number that can be 1, 2, 3 or 8, 64, 256 (computer numbers). N in block 102 in FIG. 8 is equal to N in block 44 in FIG. 4, in the same monitoring of a system. Next, the apparatus in block 104 colorizes each spatial unit according to the program shown in FIG. 3. The final output in block 106 will have each spatial unit assigned with a color hue and a color intensity. The color hue represents a wash-out pattern and the color intensity represents an initial rate of wash-in. The colored output in block 106 is fed to storage 6 in FIG. 1 or directly to the analysis means in block 7 of FIG. 1. For each color and color intensity in each spatial unit in the output in block 106 of FIG. 8 there is the same color and color intensity in at least one grid point or location in the calibration map with defined values of variables of the system. Thus, the color/color intensity in each spatial unit obtained by the processing means 5 can be related to defined values of variables determined in the calibration map. The apparatus shown in FIG. 1 functions with normalized intensities. The normalization is performed by selecting means in block 1 in FIG. 1 in the process of obtaining a calibration map defined in detail previously. The selecting means defines max intensity and uses the value of this max intensity to normalize all intensities measured to this max intensity. Alternatively, it is possible, but not preferred, to separate the normalization in reference to max intensity, performed by the selecting means, from that performed by the processing means, by choosing the maximum intensity independently by the selecting means and by the processing means. However, this weakens the correlation between the calibration map and the final output of data processing shown in block 106 of FIG. 8 and in block 126 of FIG. 9 and in block 166 of FIG. 10. Referring now to FIG. 9, there is shown a flow diagram of steps or blocks of the apparatus for processing collected data. This diagram deals with data recorded in two dimensions so that each data point is a pixel. The first step 110 in FIG. 9 is the start. This is followed by input in step 111. The input consists of the selected time points to, t1 and t2 set by the selected means in block 1 in FIG. 1 and used by the control and effect means in block 3 in FIG. 1. The spatial units n and m define a pixel in a grid. For the first pixel n=1 and m=1 and then n goes from 1 to n and m goes from 1 to m in steps of 1. Another input is the collected data I(t0), I(t1) and I(t2) of each pixel. This input can be directly obtained from the control and effect means in block 3 in FIG. 1 or from the storage in block 4 of FIG. 1. The input also includes the max intensity which is obtained in the output of the selecting means shown in block 20 in FIG. 2 or in step 56 in the flow diagram of FIG. 4. Next, the apparatus, in steps 112 and 113 in FIG. 9 selects the first pixel n=m=1 and in step 114 determines the normalized intensity in this pixel defined by the intensity function I ( t1 ) - I ( t0 ) [ I ( t0 ) ] ( t1 - t0 ) and by the normalization in reference to the max intensity of N Max Intensity where N=integer ≧1 as defined above. The normalized intensity is a measure of the initial rate for the wash-in behavior. N in step 114 is equal to N in step 44 in FIG. 4 in the same monitoring of a system. Next, this pixel (n=m=1) is colorized in steps 115 to 120 using the color function C according to the block diagram in FIG. 3 and according to steps 45 to 50 in FIG. 4. This determines wash-out pattern/color hue of this pixel. If none of the possible patterns (3 patterns) occur, for example, as 1 (t1)=0 this pixel is colored in black in step 121. In steps 122, 123, 124, 125 the next pixel is selected and a loop to step 114 that follows until step 120 determines for this next pixel the normalized intensity and the pattern/color hue. This loop is repeated for all pixels (n×m). In the output of step 126 in FIG. 9 each pixel has a wash-out pattern coded by a color and a wash-in initial rate coded by color intensity. The output is followed by step 127 which ends the flow diagram of FIG. 9. A specific example of a flow diagram of apparatus for processing data collected for tracer modulated MRI is shown in FIG. 10. The flow diagram starts with step 150. The next, step 151, is the input of the selected time points t0, t1, t2 set by the selecting means of the apparatus as shown for tracer modulated MRI in the apparatus depicted in the flow diagram of FIG. 5 and is part of the output step 86 in FIG. 5. These three time points are also used by the control and effect means for data collection in the same monitoring of the body in step 151 of FIG. 10. Maximum intensity is also obtained from the output step 86 in FIG. 4 and is obtained in the same monitoring of the system, namely, the body. The input also includes the data collected by the control and effect means as shown for tracer modulated MRI in FIG. 7. These data are recorded images. There are three recorded images or three sets of recorded images of the same area or volume. The first image or set of images is recorded prior to tracer administration. The second image or set of images is recorded at time t1 and the third image or set of images is recorded at time t2. Each pixel or voxel in the image has an MRI signal intensity which is changing with time after tracer administration. In the first image recorded prior to tracer administration, but close to the administration time, the intensity is termed Iimage1(n,m). The pixel for which n=1 and m=1 is called the first pixel with intensity Iimage1(1,1). There are n×m pixels where n goes from 1 to n and m goes from 1 to m. The intensity in each pixel (n,m) in the second image recorded at time point t1 is termed Iimage2(n,m). Similarly the intensity in each pixel (n,m) of the third image recorded at time point t2 is termed Iimage3(n,m). In steps 152 and 153 in FIG. 10 the pixels are assigned starting from n=1 and m=1. In step 154 in FIG. 10 the normalized color intensity is determined for pixel (n,m) from the values of pixel (n,m) in Iimage1(n,m) and Iimage2(n,m) according to: normalized intensity = I image2 ( n , m ) - I image1 ( n , m ) [ I image1 ( n , m ) ] ( t 1 - t 0 ) × 256 max intensity The normalized intensities are determined for all pixels by a loop in steps 162, 163, 164 and 165 until all pixels have been processed. (1) Next, in steps 155 to 160 the wash-out pattern/color is determined for each pixel (n,m) from the values Iimage2(n,m) and Iimage3(n,m) using the color function C which is defined for this specific example as: 1. C = Color Function = I image 2 ( n , m ) - I image 3 ( n , m ) I image 2 ( n , m ) and a color is chosen as shown in block 23 in FIG. 3, and as shown in steps 155 to 159 in FIG. 10. Pixels that are left uncolored through 155-160 as is the case when Iimage2(n,m)=0 are assigned black in step 161. The colorizing steps are looped by steps 162, 163, 164, 165 to include all pixels. The output in step 166 shows an n×m image in which each pixel (n,m) has a defined wash-out pattern/color hue and a defined wash-in rate/color intensity. This colored image is termed the three time points image or, in short, 3TP image. The color hue and color intensity is correlated to the calibration map and interpreted in terms of the values of microvascular permeability K and fraction of extracellular volume v, the two variables of the subject body in the calibration map of the output in step 86 in FIG. 5. Referring now to FIG. 11, there is shown a block diagram of the structure of the analysis means 7 of FIG. 1. The input in block 200 consists of the calibration map obtained by the selecting means 1 and included in the output in block 20 in FIG. 2 or in the output in block 56 in FIG. 4. The other input in block 201 of FIG. 11 is the output of the processing means shown in block 126 in FIG. 9 or in block 106 in FIG. 8. The input in block 200 and the input in block 201 are from the same monitoring of the subject system. The analysis in block 202 consists of analysis of distribution of colors and of color intensities using for example histograms. The analysis consists also of a correlation between the calibration map and the color/color intensity of each spatial unit of the input in block 201. This correlation estimates values of the variables of the calibration map for each spatial unit in the input of block 201. Finally, the apparatus in block 203 outputs the distribution analysis and the correlation with the calibration map. A specific example of that portion of the apparatus including the means for analysis of the 3TP image obtained in a tracer modulated MRI is shown in the block diagram of FIG. 12. The input in block 210 is the 3TP image. The analysis in block 212 of the 3TP image consists of analyzing color distribution and color intensity distribution, such as determining how many pixels are colored red with a certain intensity and making a similar determination for the other colors. Also, a separate analysis of intensity distribution and of color distribution can be performed. The part of the apparatus in block 211 provides means for inputting the calibration map obtained by the selecting means as shown for tracer modulated NM in FIG. 5. This calibration map is for the same t0, t1, t2 and other shared parameters as the 3TP image. Analysis of the 3TP image in terms of the two variables of the calibration map K and v is shown in block 213 of FIG. 12. This correlates color hue/color intensity in each pixel of the 3TP image to the values of the pathophysiological parameters K-microvascular permeability and v-fraction of extracellular volume determined by the color hue/color intensity in the-calibration map. Thus, the analysis is performed in terms of distributions of the two pathophysiological variables in the area or volume imaged. Finally, the apparatus in block 214 stores in a store or outputs as digital signals or displays in a display device like a monitor or is fed to a printer and a color print is obtained one or a plurality of 3TP images/and the corresponding correlated calibration maps. Another specific example relates to control and monitoring apparatus for an irrigation system. One of the most frequently used modern techniques to irrigate or water large areas in an efficient way is by drip irrigators. In the planning of such a system there are parameters such as the dimensions of the pipes, the extent and size of dripping holes and the pressure and timing of irrigation that can be adjusted according to the needs. These parameters will overall determine the rate of water dripping per unit area assigned here by the letter K. However, another parameter which will determine the efficiency of the irrigation is the water apparent diffusion constant in the ground, assigned here by the letter v. This diffusion rate or constant depends on the physical and chemical properties of the soil in the ground that the water passes through. Namely, in regions with light soil, such as sand, the apparent diffusion constant will be high while in regions with heavy soil it will be slow. Thus, the diffusion rate varies over the field needed to be irrigated. By the apparatus of the present invention it is possible to estimate K and v and then optimize the irrigation efficiency. As a preliminary matter one needs to measure the amount of water per unit weight of soil. There are several ways to determine water content. One for example is: weigh accurately an amount of soil just after digging it. Dry the soil completely and then measure again the weight. The loss in weight is equivalent to the amount of water in this sample. The samples can be taken with a spatial resolution that varies depending on the size of the field and on the accuracy needed to be reached. For example, for a very large field of tens or hundreds of square kms, it is reasonable to divide the field into 1 km′ units. Thus each pixel in the final image of irrigation constructed by the novel apparatus of the present invention and in particular by the processing means will reflect behavior per 1 km2. A sample of soil should be taken from the middle or any other defined location in this unit area of 1 km2. The size of the sample can vary but can be small of about 1 gram. The depth from which the sample should be taken can vary according to the needs. For example, if the growth of the plants to be irrigated depends on the amount of water at the level of the roots, then the sample should be taken from this level. It is also possible to use the apparatus in 3D and take samples from the same area but at varying depth. Samples should be taken from approximately the same place (the size of the sample is much smaller than the overall unit area). The apparatus of the invention performs as follows. The area to be tested has the dripping system ready for test and the positions of sampling are assigned. At a time, just before the start of the operation of the irrigation system, samples are taken from all the assigned positions. Then, at time point t0 the operation of the irrigation system is initiated for a pre-set time which ends before time point t1 which is determined by the calibration map. After the irrigation is stopped, a second sample is taken for measurement from each assigned position at time point t1. Finally, at the pre-set time point t2 a third sample from each assigned position is taken for measurement. The amount of water is then determined in the samples. For each position the water content in the three samples taken at time point t0, and at time points t1 and t2 will change according to a wash-in rate and wash-out pattern and will be characterized by the color hue/color intensity code as developed according to the novel apparatus and method of the present invention. The wash-in and wash-out behaviors depend on K=rate of water dripping per unit area and on v=water apparent diffusion constant in the ground. For the same v the initial rate will increase with K, for the same K the initial rate will increase with v. The wash-out pattern will also depend on K and v. If v is faster than K the fast wash-out pattern (assigned blue) will predominate. If K and v are of the same order, the green color, coding moderate wash-out, will predominate. If Q is lower than K a slow wash-out pattern, red will predominate. The distribution of K, v over all positions (each position is described by a pixel) is determined by correlating the coloring and color intensity of the pixels (each with the color hue and color intensity) in reference to the calibration map. The calibration map is providing wash-in intensity function and wash-out pattern in a K-v plane for t0, t1, t2 as follows: a calculation for each pair of K, v of the amount of water accumulated at time points t1 and t2 is performed based on a model known to those skilled in the art. The range of K is chosen from 0 to the maximum level of the subject irrigation system while the range of v is from 0 to the diffusion constant of pure water or, when known, the highest water diffusion constant in the field to be irrigated. To obtain optimal resolution within the range of K and v, time points to, t1 and t2 are chosen in such a way that the K-v plane will be divided between the three wash-out patterns/colors to approximately three equal areas. Once measurements have been made and the novel apparatus of the invention has performed its initial function, the apparatus can be adjusted to vary K (K can be varied since it depends on the irrigation system) in such a way that the irrigation in each defined area represented by a pixel will be the most efficient. For example, the moderate wash-out pattern (green) may be preferred in order to provide a constant amount of water over a defined time period. By increasing K it is possible to move from the blue region to the green for the same v. To assure the achievement of the final adjustment, it is possible to change K and then run the apparatus for the same three time points and positions in the subject field. Another use of the color/color intensity coded map of irrigation is the preparation of a plan of planting by adjusting the kind of plants or the density of planting to the quality of irrigation dictated by the kind of soil and the irrigation system. The new apparatus of the present invention can be utilized to test and modify the air condition planning, either for heating or for cooling or both. Described now in detail is novel apparatus for controlling and/or monitoring a heating process. For an air condition system (heating, cooling or both) built for a whole structure having within rooms or defined spaces, such as a house, a factory, an office building, shopping mall or a complex of houses, it is important to design the system in such a way that each defined space will be conditioned efficiently and then, to verify the reality. Certain regions may be overheated while others can be over cold. The adjustment by the novel apparatus for such a structure can be done by modifying the amount of heat per unit area and unit time assigned, in this example, with the letter K. The other variable that will determine the heating capacity is the, rate of heat transfer per unit area to the surrounding environment due to imperfection in the isolation, in this example assigned the letter v. The assessment of the heat is performed by measuring the temperature by thermocouples or thermometers placed at any number of locations within each room or defined space. Each thermometer position will define a pixel position in a 2D or 3D plan of the subject system (structure). At a time point prior to t0, with the system turned off, readings of all temperature measuring devices in all positions are taken, determining temperature T0. Then at time point t0 the air condition system is turned on for a pre-set time, the end of which is before and close to time point t1. At time point t1, after the system has been turned off, second readings of all devices are taken determining temperatures T1. Then, after a second preset time ending at time point t2 third readings are taken determining in each position temperature T2. The temperature changes between time points t0, t1 and t2, namely, the difference between temperatures T0, T1 and T2, for each position of measurement, will depend on the amount of conditioning per unit area per time (K) released in the room and on the amount of heat lost or gained from the outside through the walls by diffusion (v). The later parameter v can be negative or positive depending on the direction of flow of heat between the environment and the position where measurement occurs. These changes can be described by a wash-in pattern of air flow and wash-out pattern of air flow. The pattern of wash-out is described by a color hue. If the temperature T1 at time t1 is higher than the temperature T2 at time t2 the washout process is defined to be fast and is assigned blue. If T1 is smaller than T2 the wash out process is defined as slow and is assigned red. If the temperature will remain the same T1=T2 (within a range predetermined by the apparatus) the wash-out process is defined to be moderate and is assigned the green color. The brightness of the colors will depend on the initial rate defined by ( T1 - T0 ) T0 ( t1 - t0 ) (usually but not necessarily t0=0). The initial rate will also depend on K and on v. For the same v, the initial rate will increase with K. For the same K the initial rate will decrease with increasing v and will increase with decreasing v also to negative values. If the place is not well isolated and the surrounding is colder, then v will be high and the change in temperature will follow the pattern of fast wash-out. If the isolation is good (v is small and close to 0), the change in temperature will follow the pattern of moderate wash-out. If the surrounding is warmer and the room is not well isolated v will have a high negative value and the change in temperature will follow the slow wash-out pattern. Using the novel color hue/color intensity concept of the present invention it will be possible to identify places that are not well conditioned, e.g. heated, and are not well isolated and places that are over conditioned, e.g. overheated. If the air conditioning is heating, the temperature is determined by the amount of heat reaching the place where the temperature measuring device or element, e.g. thermometer, is placed and by the amount of heat that leaves this place as a result of heat loss to or heat gain from the surroundings. In certain cases defined by the size of the room and the distribution of the heat source we can assume that during the heating time the heat flow is relatively fast and equilibration in the room is rapidly achieved. Thus, the temperature will depend on the total amount of heat produced during the heating time period. K will therefore range between 0 and the maximum capacity of the heating system. The flow from or to the surroundings is determined by the same insulation, namely the same v but with opposite signs. Thus v will range between −v to +v with the actual value determined for example by the value with no insulation. The time points t0, t1 and t2 are chosen by using a calibration map constructed based on an equation known to those skilled in the art that relates the change in temperature with time to K as described above. Although, the particular example discussed related to heating, the novel apparatus can be used with the same program and means to evaluate cooling using absolute values for the changes in temperature that determine wash-out patterns and wash-in initial rates. The apparatus of the present invention includes a computer system operating electronically, optically or both having a memory, a central processing unit, a display, an input device for generating device event signals and coacting therewith software for use with the computer. The software (in binary or related form) comprises a computer usable medium having computer readable program code thereon including the program logic for implementing the various flow charts and block diagrams described above. Since the details of computers are well known in the art and because persons skilled in the art have sufficient expertise and knowledge to be capable of implementing the flow charts and block diagrams, a detailed description of the specific hardware has been omitted as superfluous and unnecessary to a full and complete understanding and appreciation of the present invention as described above. Those skilled in the art will be able to make and use the apparatus and method of the present invention from the detailed description and teachings contained herein. Summarizing the 3TP method with respect to contrast enhance MRI, for a given breast lesion, changes in MRI signal intensity (SI) reflect changes in the concentration of the contrast agent. The concentration, in turn, is predominantly determined by two pathophysiological parameters that characterize malignant tumors and differentiate them from benign ones. These parameters are: the product: (blood vessel surface area)×(permeability) per unit volume; and the extracellular volume fraction (EVF) accessible to the contrast agent. From the breast MRI images, the 3TP algorithm detects the SI at each location, pixel-by-pixel, for one pre-contrast time point and two post-contrast time points (hence the name Three Time Point, or 3TP). The algorithm then codes the SI changes between the three time points using color intensity and color hue as follows: (1) Color Intensity codes the rate at which the SI changes between the first and second time points with a resolution of 256 intensities where dark colors signify slow change and bright colors signify rapid change. (2) Color Hue is a measure of contrast washout and is coded depending on the SI change between images recorded at the second and third time points. The color coded 3TP images are related to pathophysiology via the mathematical model described above so that color hue and intensity are related to the product, (vessel surface area×permeability), and to the extravascular space (EVF), respectively, yielding a “calibration map”, used for interpretation. Cancers typically show more bright red regions, reflecting the presence of increased vessel permeability and higher cell density. Benign tumors and normal breast conditions typically demonstrate greater areas of blue, indicative of the presence of lower cell density and thus higher extracellular volume with diminished vascular permeability. i) FIG. 17 shows in view (a) that MLO mammographic projection of a 49 yo woman does not show 15 mm cancer which was palpable and diagnosed by in-office FNA as infiltrating ductal cancer; in view (b) that subtraction sagital MRI (0 minute (pre-contrast) image subtracted from 2 minute image shows ring-enhancing, spiculated malignancy in the anterior breast (arrow), and posteriorly, a small intramammary lymph note also enhances, but has a characteristic morphology, including fatty hilus (arrowhead); in view (c) that 3TP parametric similar to that of 1b, but with overlay of colored pixels superimposed on MRI image by 3TP software based on a physiological model (described in text) reveals bright red indication of high probability for malignancy and this lesion was prospectively given a score of 5 (highly suspicious for malignancy); and in view (d) shows a calibration map corresponding to the patient shown in 1a. The calibration map shows color hue (red, green, blue) based on differences in signal intensity between the second and third images of the three image 3TP image set. Color intensity is based on the difference in SI between the first and second images of the image set. As described in the text, areas of high vessel permeability×surface area and low extravascular volume fraction (EVF), typical of malignancy, are coded as bright red. For optimal discrimination of benign and malignant lesions, the imaging parameters are chosen to approximately divide the calibration map into equal areas of red, green and blue. Accuracy of diagnosis relies on judicious selection of the three time points. This selection is made by adjusting time points so that, given the imaging parameters, the red, green and blue pixels are equally distributed in this map. For the imaging parameters we employed, we found that the two post contrast imaging points that provided this optimal “calibration map” occurred at two and six minutes after contrast injection. Attempting interpretation using other time points will shift the distribution of red, green and blue pixels toward a higher sensitivity or specificity. By seeking those points in which red, green and blue pixels were equally distributed throughout the calibration map, it is hypothesized that the most accurate diagnosis could be obtained. The color convention used, is that cancer is now associated with red pixels, and benign conditions with blue pixels, contrary to any earlier convention. MR Imaging a) For a specific example of clinical testing, imaging was performed at 1.5 Tesla (GE Medical Systems, Waukesha, Wis.) using a phased array breast coil (MRI Devices, Waukesha, Wis.). A three dimensional gradient echo acquisition was employed using parameters: TR=15 msec; TE=4.2 msec; flip angle=30 degrees FOV=16-18 cm; matrix=256×256; NEX=1.0, and slice thickness=2.2-3.0 mm. Seven consecutive image sets of 56 slices (interpolated from 28 slices), were obtained over 14 minutes and 45 seconds. i) Gadodiamide (Omniscan-Nycomed Laboratories. Princeton, N.J.) was injected three minutes after the beginning of the scan series, i.e. 1 minute after the start of the second scan sequence. Contrast was administered at 2 cc/sec, followed by 15 cc of saline flush, also delivered at 2 cc/sec, using an automated pump (Medrad Corporation, Indiancis, Pa.). Image Interpretation and Data Analysis For the specific example of clinical testing, MR images were sent by File Transfer Protocol (ftp) from the laboratory performing clinical trials to the research laboratory for analysis. Interpretation of images involved visually examining each of the slices computed from imaging time points at 0, 2 and 6 minutes for a coherent group of pixels which could indicate a lesion. Prior experience with the 3TP method has shown that when a lesion has >15% red pixels, it is likely malignant; if few red pixels (<10%) are present, the lesion is likely benign. Benign lesions typically show a high fraction of blue pixels (>50%) and low color intensity. In this regard, note FIG. 18 which shows in view (a), a MLO mammographic projection showing an ovoid focal lesion along the inferior mid breast (arrow) in a 69 yo woman; pathological diagnosis, via excisional biopsy, was benign breast tissue; and in view (b) a 3TP sagital MRI parametric image showing virtually all dark blue pixels indicating a lesion with low values of vessel permeability×surface area and extravascular space—indicators of benignity; the prospective 3TP diagnosis was benign (suspicion level 2). For many lesions, diagnosis, simply based on these criteria, is conclusive. For visually indeterminate cases, a parametric 3TP image can be computed using the additional data points, 4 and 8 minutes, available as part of a seven image set. This technique shifts the calibration map towards one in which sensitivity is increased, at the price of specificity, with the idea that misdiagnosing a malignancy as benign is worse than misdiagnosing a benign lesion as malignant. With the three new time points, if the green pixels become red, the lesion can be diagnosed as malignant. FIG. 19 shows in view (a) a MLO mammographic projection showing an area of ill-defined density and architectural distortion (arrow) in a 64 yo woman; diagnosis, via excisional biopsy, was infiltrating ductal cancer; in view (b) subtraction MRI (image at 0 minutes (pre-Gd contrast) subtracted from image at time 6 minutes) showing an irregular area of enhancement corresponding to the mammographic lesion; and in view (c) top three images being magnified views from adjacent slices of the central portion of the 3TP parametric image, calculated using 0, 2 and 6 minute MR images. The results show a visually indeterminate number of red pixels. The bottom three images are these same image locations, but 3TP images recalculated using 0, 4 and 8 minute MR images. There is a shift toward an increasing number of red pixels, indicating malignancy to be more probable than benignancy. The prospective 3TP diagnosis was malignant, at suspicion level 4. The final diagnosis was graded using a scale slightly modified from the BIRAD scale used for mammographic interpretation in the United States: 1. 1=very likely to be benign 2. 2=probably benign 3. 3=indeterminate (6 month f/u) 4. 4=possibly malignant (biopsy) 5. 5=very likely to be malignant (biopsy) In the clinical test noted above, the 3TP method correctly diagnosed 27 of 31 malignant (grade 4 or 5) and 31 of 37 benign lesions (grade 1, 2 or 3). The ROC curve, based on the BIRAD-like classifications scheme is shown in FIG. 20. The ROC curve of FIG. 20 was derived from 3TP data in which lesion location was supplied to the researcher, but no other clinical information was supplied. The researcher was then asked to supply a number from 1 to 5 indicating probability for malignancy or benignity. The area under the ROC curve, Az, was 0.911 and the standard deviation in Az was 0.036. Only one lesion was graded as indeterminate (grade 3)—pathology showed a benign intraductal papilloma. The results, classified by mammographic lesion, were further categorized as follows: i) Lesion Type Sensitivity Specificity ii) All 68 lesions 87% 84% iii) 45 solid masses 96% 82% iv) Microcalcifications 63% 81% There were four false negative results: three lesions showing microcalcifications without mass and one small solid lesion. The three foci of microcalcifications were all pathologically diagnosed as ductal cancer in situ (DCIS)—two intermediate grade (8 and 14 mm); and one low grade (four ducts). One example of a false negative result is shown in FIG. 21 which shows in view (a) an optical close-up of mammographic magnification CC view—66 yo woman with cluster of microcalcifications in the superior mid breast; pathological diagnosis was DCIS, low to intermediate grade. In view (b) of FIG. 21 is shown an optical close-up of subtraction sagital MRI image—6 minutes after injection of Gadodiamide; small irregular focus of enhancement (arrow) corresponds to cluster of microcalcifications. FIG. 21 view (c) shows an optical close-up of sagital 3TP image showing an area of predominantly bright green pixels thought to be benign (score=2). A total of three out of eight DCIS lesions were misdiagnosed as benign by the 3TP method. An area of future investigation is to determine whether there is a specific pattern for DCIS that will allow increased accuracy of diagnosis. Note that five other foci of DCIS were correctly diagnosed as malignant. The misdiagnosed solid lesion measured 5 mm in diameter and had a pathological diagnosis of invasive ductal cancer. In the same breast, two larger lesions, measuring 8 and 14 mm were correctly diagnosed as malignant. Six false positive results were obtained: one 11 mm focus of fibrocystic change; one 3 mm focus of schlerosing adenosis; one 9 mm intraductal papilloma; one 10 mm focus of mixed pathology (fibrocystic change and fibroadenoma); one 3 mm intraductal papilloma and one 9 mm fibroadenoma. Of fourteen fibroadenomas, 12 were correctly diagnosed as benign, while two were thought to be a malignancies. FIG. 22 shows in view (a) ultrasound examination of a mammographically occult palpable lesion in a 45 yo woman showing a gently lobulated mass, without acoustic shadowing, typically of fibroadenoma, which was confirmed by ultrasound-guided FNA. In FIG. 22 view (b) subtraction MIP MRI, 6 minutes after Gadodiamide injection, shows that the fibroadenoma confirmed by ultrasound is the largest of multiple enhancing smaller lesions. At the workstation, many of these smaller lesions showed an enhancement profile similar to that of the larger, palpable and sonographically confirmed lesion. In clinical practice evaluation of the multiple other enhancing lesions by manual placement of an ROI is impractical. Though internal septations are said to be an important MRI sign of fibroadenoma, they were not noted in this patient. In FIG. 22 view (c) 3TP parametric image showed predominantly central bright green and peripheral blue pixels, consistent with a benign lesion (score=2). The 3TP parametric image showed no other suspicious lesions. There were 7 patients (12.5%) who inadvertently benefited from having breast MRI. In four patients, a second or even third focus of malignancy was detected that was unexpected by mammography and changed the surgical approach. An example is shown in FIG. 23 in which view (a) of an optical close-up of mammography (MLO projection) in a 44 yo woman showed a spiculated mass (straight arrow). An unexpected, mammographically occult, 2nd lesion was detected at the location indicated by the curved arrow, as a result of this patient volunteering for the 3TP clinical trial. Pathological diagnosis in both cases was infiltrating ductal cancer. As is shown in FIG. 23 view (b) a 3TP parametric sagital plane image of lesion suspected to be malignant by mammography. High predominance of bright red pixels indicates high value of the product of vascular permeability×surface area, and low extravascular volume fraction, indicating high probability of malignancy (score=5). In FIG. 23 view (c) a 3TP parametric image of a second adjacent sagital slice showed a second site very suspicious for malignancy (score 5). Both sites were biopsied confirming unsuspected multifocal malignancy. In one patient, where the radiologist, based on mammographic results, suspected a 1 cm tumor, MRI revealed that it was actually 4 cm in size, this was subsequently diagnosed as an infiltrating ductal cancer. In one patient, in whom a well marginated lesion with rapid contrast washout was seen, the surgeon declined imaging guidance in removal of the palpable lesion. However, when the pathological report described only benign breast tissue, the surgeon, based on the MRI data, was urged to repeat the ultrasound, which confirmed lack of excision. Image-guided excision was then performed, now showing a benign papilloma. Finally, in one patient, after a failed mammographically-guided localization of mammographically vague and sonographically occult lesion, MRI-guided needle localization was used to excise the lesion and arrive at the diagnosis—invasive ductal cancer. For 68 pathologically proven lesions, the 3TP method, in a heterogeneous population, achieved an overall sensitivity of 87% and a specificity of 84% for detection of malignancy. Of note is that when results from the 45 solid masses were reviewed, the 3TP method achieved a sensitivity and specificity of 96% and 82%, respectively. Only one 5 mm malignancy was misdiagnosed as benign in a patient in whom two other larger malignant (8 and 14 mm) and one benign lesion (29 mm post lumpectomy seroma) were correctly diagnosed. Although the invention has been described in detail, nevertheless changes and modifications which do not depart from the teachings of the present invention will be evident to those skilled in art. Such changes and modification are deemed to come within the purview of the present invention and the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to apparatus for monitoring a system with time in space and method therefor and more particularly relates to novel apparatus such as a unique MRI machine, a novel irrigation apparatus for testing the effectiveness of an irrigation system, a novel testing apparatus for determining the efficiency of a heating and/or cooling system, and the like, for testing or controlling a system in which fluid flows and where in the system fluid either dissipates in part or requires regeneration. 2. Description of the Prior Art Presently apparatuses are known for monitoring testing or measuring a system in which a fluid that is flowing or substances in the fluid will dissipate in part as it traverses the system or will require regeneration. For example, MRI machines are used today to create images with or without administration of a tracer-contrast agent. Customarily, the machine is controlled to take a series of images at discrete time intervals and the images are then dynamically analyzed to obtain an output result. For example, dynamic studies of contrast enhancement in breast tumors have demonstrated that the rate of change in signal intensity is an important parameter for the distinction of breast masses, leading to pharmacokinetic studies. However, it is known that as a result of tumor heterogeneity, there are significant local variations in the time evolution of contrast enhancement, and, therefore, maintaining high spatial resolution in both the recording and analysis steps is very important. In a standard clinical MRI of the breast, it is difficult to achieve high spatial resolution and also maintain high temporal resolution. In most dynamic studies performed previously, the emphasis was on high temporal resolution (at the expense of spatial resolution) monitoring the equilibration in the intravascular space and early diffusion into the extracellular space of the tissue. As a consequence, in standard MRI machines the output results are sometimes inconclusive. The foregoing is also characteristic of other systems in which a fluid flows or a component thereof dissipates in part or requires regeneration, such as, for example, an irrigation system, a heating and cooling system and the like. | <SOH> SUMMARY OF THE INVENTION <EOH>Accordingly, the object of the present invention is to provide an apparatus or a machine, and a correlated method, for monitoring a system, in which a fluid is flowing, with time in space, which will provide more conclusive results regarding system anomalies or system efficiency. The present invention relates to an apparatus for monitoring a system with time in space. The system can be physical, chemical, biological, physiological, environmental, clinical or any other system in part or in whole, the system evolving with time over space in a certain way. The apparatus of the present invention can function on the basis of one, two, three or higher dimensions. The type and extent of spatial resolution and the number of time points and their spacing, that the apparatus selects, depend on the system and can be varied with a lower limit for the number of time points of two. For example, it can be used for processing time dependent data of radiologic examinations such as MRI, ultra-sonography, X-ray tomography or conventional X-ray, or Nuclear medicine for obtaining diagnosis, prognosis and therapy follow up of tumors or any other pathological disorders. It can be utilized for processing monitoring or controlling environmental data of water irrigation. It can be used to analyze data that will permit determination of leafing areas in pipes. It can be used to analyze data obtained in the food, cosmetic and other industries which involve mixture and solution preparations and determination of their homogeneity. It can be also used to assess the efficiency of heating and/or cooling systems. There are numerous phenomena that evolve over space with time in a way that can be treated according to the present invention by utilizing a novel approach which is termed herein as by wash-in and wash-out behavior. The wash-in and wash-out are terms that are used symbolically to describe a change in one direction (wash-in) and the reverse change (wash-out) which may not be true reversal but can be any pathway that induces a change. Specifically flow of fluid in a system where the fluid or fluid component dissipates or needs to be regenerated, is described according to the invention as wash-in and washout. For any wash-in/wash-out situation, it is possible to describe n numbers of patterns of wash-out, when n can range from 1 to any integral number, 2, 3, 4 etc., on the basis of m time points, when m can range from 2 to any integral number of specific time points in the time evolution of the process. The definition of wash-out is not strict and a wash-in can become a wash-out and vice versa. For each kind of system, the apparatus of the present invention provides means for monitoring, controlling or regulating the system by providing means for setting time points and other optimal parameters of the system. This setting uses a novel calibration map based on a physical model which describes the evolution with time in an approximate or rigorous manner. These calibration maps serve also to interpret quantitatively the final color hue/color intensity coded maps obtained as one of the products of the apparatus. One particular use of the novel apparatus is for contrast enhanced MRI data in order to obtain products that facilitate specific diagnosis of cancer. The time of start of contrast administration is time point t 0 and then two post contrast time points t 1 and t 2 are utilized. These post contrast times are selected by constructing calibration maps based on modeling the kinetics of contrast enhancement that relates the wash-in/wash-out rates to two pathophysiological parameters: microvascular permeability times surface area (termed in short, microvascular permeability and represented by the letter K) and fraction of extracellular volume represented by v. The calibration map is constructed by the apparatus. | 20040329 | 20070605 | 20050217 | 77207.0 | 1 | SUN, XIUQIN | APPARATUS FOR MONITORING A SYSTEM WITH TIME IN SPACE AND METHOD THEREFOR | SMALL | 1 | CONT-ACCEPTED | 2,004 |
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10,812,972 | ACCEPTED | Automatic power conservation method for optical media and the device thereof | The present invention relates to an automatic power conservation method for an optical media and device thereof, which is capable of turning off other circuit components that are still in operation using the host inference of the optical media when the optical media enters the sleep-mode, and the host inference also being used to response to an external signal of the optical media; using the host inference to wake up those circuit components if the external input signal of the optical media requesting the optical media to exit the sleep-mode. | 1. An automatic power conservation method for an optical media, comprising: using a host inference of the optical media to turn off a plurality of circuit components that are still in operation after the optical media enters a sleep mode, and thereafter the host inference also being used to response to an external signal; using the host inference of the optical media to wake up the plural circuit components if the external signal requests the optical media to leave the sleep mode. 2. The automatic power conservation method for an optical media of claim 1, the method further comprising: using the host inference of the optical media to successively turn off a micro-computing unit first, and then the other operating circuit components. 3. The automatic power conservation method for an optical media of claim 2, the method further comprising: using the host inference of the optical media to successively turn off the micro-computing unit first, a RAM arbitrator, and a DRAM. 4. The automatic power conservation method for an optical media of claim 3, the method further comprising: using the host inference of the optical media to wake up some of the plural circuit components first before the micro-computing unit being wakened up. 5. The automatic power conservation method for an optical media of claim 4, the method further comprising: using the host inference of the optical media to successively wake up the RAM arbitrator, and finally the micro-computing unit. 6. The automatic power conservation method for an optical media of claim 1, the method further comprising: using the host inference of the optical media to response to a signal sent from a host connecting to the optical media while the optical media enters the sleep-mode. 7. The automatic power conservation method for an optical media of claim 6, wherein the host is a personal computer. 8. The automatic power conservation method for an optical media of claim 7, wherein the signal is an ATAPI command signal. 9. The automatic power conservation method for an optical media of claim 8, wherein the ATAPI command signals include a Test Unity command signal and a Request Sense command signal. 10. The automatic power conservation method for an optical media of claim 8, wherein the optical media is being waked up and exits the sleep mode using the host inference of the optical media while the signal sent from the host is not one of the following: the Test Unity command signal and the Request Sense command signal. 11. The automatic power conservation method for an optical media of claim 1, wherein the host inference responses to the external signal inputted through a panel of the optical media when the optical media is entering the sleep mode. 12. The automatic power conservation method for an optical media of claim 11, wherein the signal inputted through the panel includes the signal generated by pressing an external input button of said panel. 13. The automatic power conservation method for an optical media of claim 12, wherein said external input button is one of the following: a play button and an eject button. 14. An automatic power conservation device for an optical media, featuring: a host inference of the optical media having a firmware embedded therein capable of responding to an external signal inputted from outside the optical media. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic power conservation method for an optical media and device thereof, and more particularly, to an automatic power conservation method for an optical media and device thereof that is capable of turning off more circuit components while operating in the sleep-mode. 2. Description of the Prior Art Energy conservation is a common issue that is being discussed in this era which energy is consumed rapidly. Energy conservation is also an important task while designing an optical media such as CD-ROM, CD-R/RW, DVD-ROM, DVD-R, and DVD-Dual, etc. It is most desirable if the unneeded circuit components of an optical media can all be turned off while it enters the sleep-mode, which it is the main object of the present invention. Typically, an optical media will enter the sleep-mode after idling for a period of time. The motor inside the optical media will be stopped to reduce the noise and the heat, and a portion of the circuit components on the circuit board will be turned off as well. However, when entering the sleep-mode, some of the components on the circuit board are still functioning, which include the host inference (HI) of the integrated circuit (IC) Random Access Memory Arbiter (RAM Arbiter), Micro-Computing Unit (MCU), and Dynamic RAM (DRAM). Please refer to FIG. 1, which is a block diagram of the circuitry between the PC and the IC of a conventional optical media. As the optical media enters the sleep-mode, the PC, or the Host 150 will send some signals to the HI 120 of the IC 100 in the optical media. Based on the signal received by the HI 120 from the Host 150, the MCU 110 of the IC 100 will send the information of the current operating mode of the optical media to the Host 150 through the HI 120 in response. The optical media can leave the sleep-mode by requesting from the user through the Host 150, or through the panel of the optical media (which is not shown in the figure). However, the user wakes the optical media up from the sleep-mode either through the Host 150 or the panel, the control signal needs to be sent from the HI 120 to the MCU 110 so that the MCU 110 can ask the optical media to leave the sleep-mode. Moreover, while processing these signals, the MCU 110 needs to access the DRAM 140 outside the IC 100 through the RAM Arbiter 130. Therefore, while the foregoing conventional mechanism for optical media is in the sleep-mode, the HI 120, the MCU 110, the RAM Arbiter 130, and the DRAM 140 of the optical media are, instead of in the sleep-mode, still processing. If these circuit components can as well enter the sleep-mode as the optical media entering the same, the power can be conserved. In view of this, the present invention provides an automatic power conservation method for optical media to conserve more power by turning off more circuit components when the optical media enters the sleep-mode. SUMMARY OF THE INVENTION The primary object of the present invention is to provide an automatic power conservation method for optical media that, when the optical media enters the sleep-mode, the HI of the optical media will turn off other circuit components that are still in operation and thereafter the HI is also being used for issuing a response to an external signal received by the optical media. If the external signal requests the optical media to leave the sleep-mode, the HI will wake up those circuit components that are turned off by the same. In the preferred embodiment of the present invention, the HI will first turn off the MCU in the IC, and then the other circuit components that are still in operation will be turned off thereafter. That is, the HI will successively turn off the MCU off first, then the RAM Arbiter and the DRAM. On the contrary, the HI will wake up some of those circuit components before the MCU is being wakened up. In other words, the HI will successively wake up the RAM Arbiter, the DRAM, and finally the MCU. However, as the optical media enters the sleep-mode, the HI will response to external signals received by the optical media, such as signals transmitted from the host of a PC or the input panel of the optical media. The other object of the present invention is to provide an automatic power conservation device for optical media that the host inference of the optical media possesses the firmware capable of responding to an external signal. To sum up, the present invention provides an automatic power conservation method for optical media and the receiving method thereof that is capable of conserving more energy by turning off more circuit components when entering the sleep-mode. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the circuitry between the PC and the IC of a conventional optical media. FIG. 2 is a flowchart depicting an automatic power conservation method for optical media according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In order to turn off more circuit components when the optical media enters the sleep-mode, such as the MCU and the RAM Arbiter inside the IC or the DRAM outside the IC, the present invention utilizes the HI in the IC of the optical media to response to the external signal directly when in the sleep-mode, instead of responding by the MCU. Therefore, if the optical media can operate using this mechanism (AUTOACK) when entering the sleep-mode, the MCU and the related circuit components posterior to the MCU surely can be turned off so that the power conservation can be achieved when the optical media enters the sleep-mode. To further describe the objects and features of the present invention, drawings and detailed description of the preferred embodiment are presented. Please refer to FIG. 2, which is a flowchart depicting an automatic power conservation method for optical media according to a preferred embodiment of the present invention. Before entering the sleep mode when the optical media is on, the optical media is in a normal mode as seen in Step 201. In step 202, After the optical media enters the sleep-mode, the HI inside the IC of the optical media will make an evaluation depending on the idling time of the optical media to determine whether to execute the power conservation function, or AUTOACK, by the the firmware embedded therein. As the optical media had entered the sleep-mode and had idled for a period of time, the HI will execute the AUTOACK and turn off the circuit components that are still in operation, such as the MCU and the RAM Arbiter in the IC, and the DRAM outside the IC. In the preferred embodiment of the present invention, the FI will turn off the MCU first in considering that the MCU consumes most of the power as seen in step 203. In step 204, after turning off the MCU, the HI will then turn off other circuit components that are in operation, such as the RAM Arbiter and the DRAM. If the optical media haven't been idled for a certain period of time after the optical media enters the sleep-mode, the HI will not execute the AUTOACK function and the optical media will be in the normal mode, which is represented by step 202 to 201. On the contrary, after HI executes the AUTOACK function and turns off the circuit components that are still in operation as the optical media entered the sleep-mode, the HI plays the role of the MCU in the sleep-mode of a conventional optical media, that the HI will response to the external signals sent from the host of the optical media, or the PC, such as the Test Unity Ready and the Request Sense signals from the PC through the ATAPI interface of the optical media. Assuming the signal sent from the PC to the HI is the Request Sense ATAPI command, the HI will decode the same automatically for determining the transferring mode (PIO/DMA/UDMA) and the amount of data to be transferred, and then transfers a table data to the host so that the host knows the error code of the optical media, and a interrupt signal is being issued automatically by the HI after the transferring so that the optical media can still remain in the sleep-mode, which is represented by Steps 205 to 204. However, if the ATAPI signal from the host is neither the Test Unity Ready nor the Request Sense, or if the play or the eject button on the optical media's panel is being pressed by the user, the HI will first wake up the RAM Arbiter and the DRAM, which is represented by Steps 205 to 206. The HI will then wake up the MCU thereafter, which is represented by Steps 206 to 207. Therefore, by utilizing the AUTOACK function, the optical media can turn off the circuit components, such as the MCU, the RAM Arbiter, and the DRAM, that are still in operation in a convention optical media when the optical media enters the sleep-mode, such that the power consumption can be reduced efficiently. According to the experiments, the power consumption of the optical media without using the AUTOACK function is 120 mA, while the consumption is significantly reduced to 90-100 mA when the AUTOACK function is on. In summary, the present invention provides an automatic power conservation method for optical media and device thereof, which is capable of conserving more power by turning off more circuit components when entering the sleep-mode and is realized by the firmware programmed in the HI so that the HI can response to the host of the optical media. While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to an automatic power conservation method for an optical media and device thereof, and more particularly, to an automatic power conservation method for an optical media and device thereof that is capable of turning off more circuit components while operating in the sleep-mode. 2. Description of the Prior Art Energy conservation is a common issue that is being discussed in this era which energy is consumed rapidly. Energy conservation is also an important task while designing an optical media such as CD-ROM, CD-R/RW, DVD-ROM, DVD-R, and DVD-Dual, etc. It is most desirable if the unneeded circuit components of an optical media can all be turned off while it enters the sleep-mode, which it is the main object of the present invention. Typically, an optical media will enter the sleep-mode after idling for a period of time. The motor inside the optical media will be stopped to reduce the noise and the heat, and a portion of the circuit components on the circuit board will be turned off as well. However, when entering the sleep-mode, some of the components on the circuit board are still functioning, which include the host inference (HI) of the integrated circuit (IC) Random Access Memory Arbiter (RAM Arbiter), Micro-Computing Unit (MCU), and Dynamic RAM (DRAM). Please refer to FIG. 1 , which is a block diagram of the circuitry between the PC and the IC of a conventional optical media. As the optical media enters the sleep-mode, the PC, or the Host 150 will send some signals to the HI 120 of the IC 100 in the optical media. Based on the signal received by the HI 120 from the Host 150 , the MCU 110 of the IC 100 will send the information of the current operating mode of the optical media to the Host 150 through the HI 120 in response. The optical media can leave the sleep-mode by requesting from the user through the Host 150 , or through the panel of the optical media (which is not shown in the figure). However, the user wakes the optical media up from the sleep-mode either through the Host 150 or the panel, the control signal needs to be sent from the HI 120 to the MCU 110 so that the MCU 110 can ask the optical media to leave the sleep-mode. Moreover, while processing these signals, the MCU 110 needs to access the DRAM 140 outside the IC 100 through the RAM Arbiter 130 . Therefore, while the foregoing conventional mechanism for optical media is in the sleep-mode, the HI 120 , the MCU 110 , the RAM Arbiter 130 , and the DRAM 140 of the optical media are, instead of in the sleep-mode, still processing. If these circuit components can as well enter the sleep-mode as the optical media entering the same, the power can be conserved. In view of this, the present invention provides an automatic power conservation method for optical media to conserve more power by turning off more circuit components when the optical media enters the sleep-mode. | <SOH> SUMMARY OF THE INVENTION <EOH>The primary object of the present invention is to provide an automatic power conservation method for optical media that, when the optical media enters the sleep-mode, the HI of the optical media will turn off other circuit components that are still in operation and thereafter the HI is also being used for issuing a response to an external signal received by the optical media. If the external signal requests the optical media to leave the sleep-mode, the HI will wake up those circuit components that are turned off by the same. In the preferred embodiment of the present invention, the HI will first turn off the MCU in the IC, and then the other circuit components that are still in operation will be turned off thereafter. That is, the HI will successively turn off the MCU off first, then the RAM Arbiter and the DRAM. On the contrary, the HI will wake up some of those circuit components before the MCU is being wakened up. In other words, the HI will successively wake up the RAM Arbiter, the DRAM, and finally the MCU. However, as the optical media enters the sleep-mode, the HI will response to external signals received by the optical media, such as signals transmitted from the host of a PC or the input panel of the optical media. The other object of the present invention is to provide an automatic power conservation device for optical media that the host inference of the optical media possesses the firmware capable of responding to an external signal. To sum up, the present invention provides an automatic power conservation method for optical media and the receiving method thereof that is capable of conserving more energy by turning off more circuit components when entering the sleep-mode. | 20040331 | 20080826 | 20050526 | 70696.0 | 0 | CHANG, ERIC | AUTOMATIC POWER CONSERVATION METHOD FOR AN OPTICAL MEDIA DEVICE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,812,992 | ACCEPTED | Methods and systems in monitoring tools for effective data retrieval | Systems and methods are provided for accessing and presenting data in real-time. In one exemplary embodiment, the systems and methods may include presenting a first record set, fetching a second record set before a data request, and presenting the second record set in response to the data request. The first record set may be associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part. The second record set may be associated with at least one of a second part monitored by the monitoring system, a second location, and a second supplier. | 1. A method for presenting data in a monitoring system, the method comprising: presenting a first record set in response to a data query, the first record set being associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part; fetching a second record set before receiving a data request, the second record set being associated with at least one of a second part monitored by the monitoring system, a second location, and a second supplier; and presenting the second record set in response to receiving the data request. 2. The method according to claim 1, further comprising: fetching at least one record in the second record set when the at least one record in the second record set becomes outdated. 3. The method according to claim 2, wherein fetching at least one record in the second record set when the at least one record in the second record set becomes outdated, occurs at the time the data request is received. 4. The method according to claim 1, wherein presenting the first record set includes displaying at least a portion of the first record set as a current page. 5. The method according to claim 1, wherein presenting the second record set includes displaying at least a portion of the second record set as a next page. 6. The method according to claim 1, wherein presenting the second record set includes displaying at least a portion of the second record set as a previous page. 7. The method according to claim 4, wherein presenting the second record set includes displaying at least a portion of the second record set as at least one of a previous line item before the current page and a next line item after the current page. 8. The method according to claim 1, wherein a record in the first record set includes at least one of a supplier identification, a part identification, a part description, a part location, a part order status, a number of backorder lines, a number of backorder pieces, a number of emergency order lines, and a number of emergency order pieces. 9. The method according to claim 1, wherein fetching comprises fetching the second record set substantially in parallel with presenting the first record set. 10. The method according to claim 1, wherein fetching comprises fetching the second record set in anticipation of receiving the data request for the second record set. 11. The method according to claim 1, wherein fetching the second record set comprises fetching the second record set from at least one database. 12. The method according to claim 1, wherein fetching comprises fetching the second record set from a plurality of databases. 13. The method according to claim 1, further comprising using, as the data request, a scroll command for a scrolling window. 14. The method according to claim 1, further comprising using, as the data request, at least one of a next page command and a previous page command from a user. 15. The method according to claim 1, wherein fetching further comprises fetching the second record set asynchronously with receiving the data request. 16. A monitoring system for presenting data in real-time, the system comprising: a processor; and a memory, wherein the processor and the memory are configured to perform a method comprising: presenting a first record set associated with at least one of a first part monitored by the monitoring system, a first location, and a first supplier; fetching a second record set before receiving a data request, wherein the second record set is associated with at least one of a second part monitored by the monitoring system, a second location of the first part, and a second supplier of the first part; and presenting the second record set in response to receiving the data request. 17. The monitoring system according to claim 16, the method further comprises: fetching at least one record in the second record set when the at least one record in the second record set becomes outdated. 18. The monitoring system according to claim 17, wherein fetching at least one record in the second record set when the at least one record in the second record set becomes outdated, occurs at the time the data request is received. 19. The monitoring system according to claim 16, wherein a record in the first record set includes at least one of a supplier identification, a part identification, a part description, a part location, a part order status, a number of backorder lines, a number of backorder pieces, a number of emergency order lines, and a number of emergency order pieces. 20. The monitoring system according to claim 16, wherein fetching comprises fetching the second record set substantially in parallel with presenting the first record set. 21. The monitoring system according to claim 16, wherein fetching comprises fetching the second record set in anticipation of receiving the data request for the second record set. 22. A computer-readable medium containing instructions to configure a monitoring system to perform a method for presenting data in real-time, the method comprising: presenting a first record set associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part; fetching a second record set before receiving a data request, wherein the second record set is associated with at least one of a second part monitored by the monitoring system, a second location, and a second supplier; and presenting the second record set in response to receiving the data request. 23. The computer-readable medium according to claim 22, wherein the method further comprises: fetching at least one record in the second record set when the at least one record in the second record set becomes outdated. 24. The computer-readable medium according to claim 23, wherein fetching at least one record in the second record set when the at least one record in the second record set becomes outdated, occurs at the time the data request is received. 25. The computer-readable medium according to claim 22, wherein a record in the first record set includes at least one of a supplier identification, a part identification, a part description, a part location, a part order status, a number of backorder lines, a number of backorder pieces, a number of emergency order lines, and a number of emergency order pieces. 26. The computer-readable medium according to claim 22, wherein fetching comprises fetching the second record set substantially in parallel with presenting the first record set. 27. The computer-readable medium according to claim 22, wherein fetching comprises fetching the second record set in anticipation of receiving the data request for the second record set. 28. A user interface comprising: a selection area for requesting a first record set associated with at least one of a first part monitored by a monitoring system, a first location of the first part, and a first supplier of the first part; means for making a data request for a second record set after the first record set has been fetched for display by the monitoring system, wherein the second record set is associated with at least one of a second part monitored by the monitoring system, a second location, and a second supplier; and a results area for viewing the second record set in response to receiving the data request. 29. The user interface according to claim 28, wherein the means for making the data request includes a scroll bar. 30. The user interface according to claim 28, wherein the means for making the data request includes at least one of a previous page button and a next page button. 31. A system for presenting data in real-time, the system comprising: means for presenting a first record set associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part; means for fetching a second record set before receiving a data request, wherein the second record set is associated with at least one of a second part monitored by the monitoring system, a second location, and a second supplier; and means for presenting the second record set in response to receiving the data request. 32. A method for presenting data, the method comprising: presenting a first record of a plurality of records, such that the first record includes at least one of a first part, a first location, and a first supplier; fetching a second record from the plurality of records before receiving a data request for the second record, such that the second record includes at least one of a second part, a second location, and a second supplier; and presenting the fetched second record in response to receiving the data request. 33. The method of claim 32, further comprising: defining the first part as different than the second part. 34. The method of claim 32, further comprising: defining the first part as the same as than the second part. 35. A monitoring system for presenting data, the system comprising: a processor; and a memory, wherein the processor and the memory are configured to perform a method comprising: presenting a first record of a plurality of records, such that the first record includes at least one of a first part, a first location, and a first supplier; fetching a second record from the plurality of records before receiving a data request for the second record, such that the second record includes at least one of a second part, a second location, and a second supplier; and presenting the fetched second record in response to the data request. 36. A computer-readable medium containing instructions to configure a data processor to perform a method for presenting data, the method comprising: presenting a first record of a plurality of records, such that the first record includes at least one of a first part, a first location, and a first supplier; fetching a second record from the plurality of records before receiving a data request for the second record, such that the second record includes at least one of a second part, a second location, and a second supplier; and presenting the fetched second record in response to the data request. 37. A method for presenting data in a monitoring system in real-time, the method comprising: presenting a first record set in response to a data query in a monitoring system; fetching a second record set before receiving a data request, the second record set containing a more current version of at least one record in the first record set; and presenting the second record set in response to receiving the data request. 38. The method of claim 37, further comprising determining whether a record in the first record set is current according to a timestamp associated with the first record set. 39. The method according to claim 38, wherein fetching the second record set occurs when the record in the first record set is not current. 40. A system for presenting data in a monitoring system in real-time, the system comprising: a processor; and a memory, wherein the processor and the memory are configured to perform a method comprising: presenting a first record set in response to a data query in a monitoring system; fetching a second record set before receiving a data request, the second record set containing a more current version of at least one record in the first record set; and presenting the second record set in response to receiving the data request. 41. A computer-readable medium containing instructions to configure a system to perform a method for presenting data in real-time, the method comprising: presenting a first record set in response to a data query in a monitoring system; fetching a second record set before receiving a data request, the second record set containing a more current version of at least one record in the first record set; and presenting the second record set in response to receiving the data request. | BACKGROUND OF THE INVENTION I. Technical Field The present invention generally relates to methods and systems for accessing and presenting data. More particularly, the invention relates to methods and systems in which data may be accessed from one or more databases in real-time to facilitate, for example, shortage monitoring in a supply chain management system. II. Background and Material Information In today's world of business, with global competition running rampant and consumer expectations ever-increasing, the efficiency of a business enterprise is becoming more important than ever. No longer will a consumer accept any delay in satisfying their mounting appetite for goods and services. They want their goods and services immediately, and in addition, demand the highest quality at the lowest cost. Hence, many businesses use supply chain management to control and optimize their production and cost. Supply chain management is a set of approaches and processes for efficiently integrating suppliers, manufacturers, warehouses, and stores, so that merchandise is produced and distributed at the right quantities, to the right locations, and at the right time, in order to minimize system-wide cost while satisfying service level requirements. A supply chain is a network of facilities and distribution options that procures and acquires material, processes and transforms the material into intermediate and finished products, and distributes the finished products to customers, whether intermediate or final ones. Supply chains exist both in manufacturing as well as in service organizations. Currently, technology is available to help manage a business's supply chain. However, as the needs of a large and growing business increase, more is expected for the business to stay competitive and fewer disruptions in the business's supply chain are tolerated. This is because any disruption can have extremely negative consequences on the business's reputation, market share, profitability, and ultimately, survivability. Particularly, shortages of parts or services in the supply chain can have immense impact on the efficiency of the business, including creating delays or even complete stoppages of the business's production. Accordingly, it would be beneficial to facilitate the management of supply chains, and in particular, facilitate real-time monitoring of parts or services in the supply chain. Moreover, it would be beneficial to access data in real-time to facilitate supply chain management including, for example, monitoring and managing supply shortages. SUMMARY OF THE INVENTION Methods, systems, and articles of manufacture consistent with the present invention may facilitate the access of data. More particularly, methods, systems and articles of manufacture consistent with the invention facilitate data access, whereby the data may be accessed in real-time from one or more databases to perform, for example, shortage monitoring in a supply chain management system. One exemplary aspect of the invention relates to a method for presenting data in a monitoring system in real-time. The method may include: presenting a first record set; fetching a second record set before a data request; and presenting the second record set in response to the data request. The first record set may be associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part. The second record set may be associated with at least one of a second part monitored by the monitoring system, a second location of the first part, and a second supplier of the first part. Another exemplary aspect of the invention relates to a method for presenting data in real-time. The method may include presenting a first record of a plurality of records; fetching a second record from the plurality of records before receiving a data request for the second record; and presenting the fetched second record in response to receiving the data request. The first record may include at least one of a first part, a first location, and a first supplier. The second record may include at least one of a second part, a second location, and a second supplier. Another exemplary aspect of the invention relates to a method for presenting data in a monitoring system in real-time. The method may include: presenting a first record set in response to a data query in a monitoring system; fetching a second record set before receiving a data request; and presenting the second record set in response to receiving the data request. The second record set may contain a more current version of at least one record in the first record set. Another exemplary aspect of the invention relates to a monitoring system. The monitoring system may include a processor and a memory configured to perform a method for presenting data in real-time. Another exemplary aspect of the invention relates to a computer-readable medium containing instructions to configure a monitoring system to perform a method for presenting data in real-time. Another exemplary aspect of the invention relates to a user interface for presenting data in real-time. Additional aspects of the invention are set forth in the detailed description which follows or may be learned by practice of methods, systems, and articles of manufacture consistent with the present invention. It is understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. In the drawings: FIG. 1 illustrates an exemplary supply chain environment consistent with the present invention; FIG. 2 illustrates an exemplary shortage management monitoring system consistent with the present invention; FIG. 3 illustrates exemplary shortage monitor interface elements consistent with the present invention; FIG. 4 illustrates exemplary selection and results areas consistent with the present invention; FIGS. 5A-5C illustrate exemplary selection interface areas consistent with the present invention; FIG. 6 illustrates an exemplary supplier summary consistent with the present invention; FIG. 7 illustrates an exemplary method for accessing and presenting data in real-time consistent with the present invention; and FIGS. 8A and 8B illustrate exemplary presentations of first and second record sets consistent with the present invention. DETAILED DESCRIPTION Reference is now made in detail to exemplary aspects of the invention, examples and embodiments of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. For the purposes of this application, the supply, production, and distribution of automotive products are discussed. However, as one of ordinary skill in the art will appreciate, the supply, production, and distribution of other products and services, such as computers, televisions, tools, and other items of commerce, may also follow the same or similar course to the marketplace. Accordingly, features and principles of the present invention are not limited to the supply chain (e.g., supply, production, and distribution) of automotive products, but are equally applicable to other products and services placed in commerce. FIG. 1 illustrates an exemplary supply chain environment 100 for automotive parts, consistent with features and principles of the present invention. Supply chain 100 may include raw material supplier(s) 102, intermediate manufacturer(s) 104, finished product manufacturer(s) 106, distributor(s) 108, retailer(s) 110, and consumer(s) 112. Raw material suppliers 102 may furnish basic materials (e.g., rubber, iron, glass, etc.) to intermediate manufacturers 104. From the basic materials, intermediate manufacturers 104 may produce intermediate products or parts (e.g., tires, mufflers, windshields, etc.) for finished product manufacturers 106 or distributors 108. Using the intermediate products, finished product manufacturers 106 may manufacture finished products (e.g., cars, trucks, motorcycles, etc.) for distributors 108. Distributors 108 may supply retailers 110 with the intermediate or finished products, and retailers 110 may sell them to consumers 112. Each stage 102-112 of supply chain 100 may involve many suppliers providing their respective products or services to the next stage. For example, there may be hundreds of intermediate manufacturers 104 that produce similar or different parts, which finished product manufacturers 106 may use as needed to produce its finished products. Hence, each stage 102-112 of supply chain 100 may include multiple redundant suppliers of a particular part or product. As one of ordinary skill in the art will appreciate, each stage 102-112 may depend on the availability of parts or products from a previous stage. For example, if a part is not timely available from any stage 102-104, then finished product manufacturer 106 may have a shortage of parts necessary to produce its finished products. The part may be something as unremarkable as a fastener for a muffler. However, without the missing part, finished product manufacturer 106 can not complete assembly of its finished product (e.g., automobile), which creates shortage problems that are cascaded to later stages 108-112. At this point, the availability of backup suppliers and emergency suppliers for stages 102 and 104 would be useful in maintaining the stock of available parts to finished product manufacturer 106. In one exemplary embodiment consistent with the present invention, shortages in a supply chain may be monitored and controlled using a shortage management monitor system, such as the exemplary monitor system 200 illustrated in FIG. 2. Monitor system 200 may watch over critical (i.e., out-of-stock) parts, potentially critical (i.e., low supply) parts, and remaining parts for a business's production line and its suppliers. The business and its suppliers may use monitor system 200 to take immediate action on shortage parts and to take preventive action on potential shortage parts. Monitor system 200 may display different internal and external information for the business and suppliers, respectively, and may use a login interface to differentiate between the two. The business may use monitor system 200 to view parts information, and the suppliers may use monitor system 200 to enter promises, a delivery schedule, and/or remarks for the parts. Monitor system 200 may include a processor 202, a memory 204, an input/output (I/O) device 206, a display 208, a network interface 210, a bus 212, a network 214, and one or more persistent storage devices 216 and 218. Processor 202, memory 204, I/O device 206, display 208, network interface 210, and storage device 216 may be configured to communicate over bus 212. Storage device 218 and network interface 210 may be configured to communicate over network 214. In one exemplary embodiment, monitor system 200 may be incorporated into a parts planning system, such as the Advanced Planning Optimizer (APO) available from SAP AG (Walldorf, Germany). Processor 202 may include a mainframe, a laptop, a personal computer, a workstation, a computer chip, a digital signal processor board, an analog computer, a plurality of processors, or any other information processing device or combination of devices. Further, processor 202 may be implemented by a general purpose computer or data processor selectively activated or reconfigured by a stored computer program, or may be a specially constructed computing platform for carrying out the features and operations disclosed herein. Memory 204 may include random access memory, read-only memory, flash memory, or any other information storage device. I/O device 206 may include a keyboard, a mouse, a trackball, a light pen, an electronic tablet, or any other mechanism that can provide information to monitor system 200. Display 208 may include a cathode-ray-tube monitor, a plasma screen, a liquid-crystal-display screen, or any other device for conveying information from monitor system 200. Network interface 210 may include an Ethernet card, a FDDI card, a modem, or any other mechanism for interfacing to a network. Bus 212 may include a data cable, a circuit board connection, a fiber optic line, a network, a serial connection, a parallel connection, or any other mechanism for conveying information between processor 202, memory 204, I/O device 206, display 208, network interface 210, and/or storage device 216. Network 214 may include a local area network, a wide area network, an intranet, an extranet, the Internet, a telephone network, a wireless network, a wired network, or any other means for communicating between locations. Storage devices 216 and 218 may include a hard drive, a tape drive, a RAID disk array, a database system, a optical disk drive, or any other device or system that persistently stores information. In one exemplary embodiment consistent with the present invention, monitor system 200 may be configured with shortage monitor elements, such as shortage monitor elements 300 illustrated in FIG. 3, to manage a business's supply chain and shortages of supplier parts. Elements 300 may be a set of different screens or user interfaces and may include a supplier summary 302, a shortage summary 304, a shortage part overview 306, a remarks information view 308, a supply manager 310, and/or a part detail information view 312. Elements 300 may act as interfaces to database(s) of parts or supplier information for the business and may be used to determine, analyze, and forecast shortages of parts. Further, an internal user may navigate between elements 300 to obtain information about a part. Suppliers may also access portions of elements 300, analyze parts that they supply to the business and are responsible for, and send promises and/or advanced shipping notifications (ASN) on critical or potentially critical parts, thus helping to avoid shortages for parts that they provide. Elements 300 may be implemented in software or firmware, such as HTML, Java, Visual Basic, C, COBOL, FORTRAN, assembly language, machine code, and/or any other programming language. Supplier summary 302 may show a view of all suppliers that supply a selected part and may list supplier information (e.g., supplier identification or name, number of back order lines, quantity of back order pieces available or on order, number of emergency order lines, quantity of emergency order pieces available or on order, etc.). Shortage summary 304 may summarize information on all parts matching a query (e.g., a request for parts ranging between P and Q, at locations L1 to L2, etc.). Shortage part overview 306 may allow a user to analyze shortages by parts and location of the parts or by status of orders to suppliers (e.g., part delivery scheduled, part delivery late, etc.). Remarks information view 308 may list simple remarks (e.g., text) entered by a user for specific parts. The remarks may be dated, time-stamped, and hidden or unhidden from suppliers that use monitor system 200. Supply manager 310 may allow a supplier with valid authorization to enter a supplier promise for a part, including a part quantity and ship date. Part detail information view 312 may show detailed data for a part, such as part master data, stock information, demand and forecast information, remarks, distribution requirements planning (DRP) information, schedule information, ASN information, order information, lead-time information, supplier promises, supplier information, etc. In general, each of elements 300 may include selection and results areas, such as the selection area 402 and a results area 404 illustrated in FIG. 4. Selection area 402 may accept selections (i.e., queries) from users for specific part order information stored in storage devices 216 and 218 (FIG. 2) and/or other databases. Selection area 402 may include a simple selection interface (see, e.g., FIG. 5A) or an advanced selection interface (see, e.g., FIG. 5B). The simple selection interface may allow a user to specify supplier product(s) or location(s) with supplier products that the user wishes to monitor or obtain information on. The advanced selection interface may allow the user to make more complex selections (e.g., parts or locations between, not between, or not equal to user-defined parameter values). Selections may be preconfigured and saved for later use via a selection creation interface (see, e.g., FIG. 5C). The saved selections may have different access levels to limit their availability to qualified users (e.g., administrator level, specific user, etc.) or may be a default selection. When a user enters a selection in selection area 402 (FIG. 4), monitor system 200 (FIG. 2) may fetch parts and order information, from storage devices 216 and 218 (and/or other databases), that match the selection and display them to the user. The output results (i.e., the parts and order information) of the selection may be displayed in results area 404. For example and as shown in FIG. 4, the output results may include a list of suppliers, products supplied by the suppliers, locations of the products, frequency of demand for the products, requisition status of the products, number of emergency orders, number of back orders, days on hand (DoH), or any other information. Monitor system 200 may present the output results in tabular, list, or any other form. In many cases, the number of parts and order information meeting the query's criteria may exceed the available space to display the information in results area 404. Indeed, the number of parts may number in the hundreds, thousands or even millions. Hence, monitor system 200 may only display a portion of the parts and order information meeting the query's criteria, such as that displayed in the example of FIG. 4. In another example, as illustrated in a detailed view 600 (FIG. 6) of supplier summary 302 (FIG. 3), a user may enter selection criteria in the selection area 602 for supplier summary 302. The selection criteria may be a search for specific tire parts. After monitor system 200 fetches the information matching the criteria, supplier summary 302 may show a list of all suppliers that supply the specific tire parts and may list supplier information in its result area 604. The supplier information may include supplier names, number of back order lines, number of back order pieces, number of emergency order lines, number of emergency order pieces, etc. Particularly, as shown in FIG. 6, supplier S1, S2, S3, and S4 may be listed to have back orders of five, one, zero, and zero tires, respectively. If the amount of requested information will exceed the display in result area 602, monitor system 200 may only just fetch enough information to fill results area 602 and collect additional information for a next screen of information in real-time as the user makes data requests when navigating through the information. In large and fast-paced businesses with extremely large numbers of suppliers and parts, parts information may easily be outdated because the parts information may be in a constant state of flux. Moreover, the parts information may be distributed across several databases making it difficult to fetch and display accurate parts information. By collecting and displaying information in real-time, as needed, and as the user navigates through the information, monitor system 200 may provide the most up-to-date information to the user. For example, many users may be concurrently accessing and modifying parts information stored in monitor system 200. If a user makes a request for parts information via selection area 402 (FIG. 4) and receives all information matching his criteria whether or not all the information can be displayed at once in results area 404, then as the user navigates through the fetched version of the information to view each portion of the information, the user has no idea whether the fetched version still reflects the parts information stored in monitor system 200 or some other location. This is because the fetched version may be sitting in memory while other users are modifying or have modified a master version of the parts information stored in monitor system 200 or at databases at some other locations. However, if monitor system 200 only fetches enough information from storage devices 216 and 218 as can be displayed (e.g., a predetermined number of entries or record set that can be displayed) and then fetches additional information as the user scrolls or pages through the information, then monitor system's 200 response time to the user may appear sluggish. That is, in a system with a very large amount of parts and supplier information, each fetch may require a noticeable amount of time to complete because of the sheer size of information that needs to be examined and the database(s) that need to be accessed. For example, a car may have millions of part entries from thousands of suppliers. Hence, if monitor system 200 synchronously fetches additional information after or immediately after a user indicates he wishes to see the additional information, then the user may notice an unacceptable delay before receiving the additional information. A compromise between fetching too much information (e.g., all information meeting selection criteria) and too little information (e.g., only one line of information meeting selection criteria) for display may be appropriate. In one exemplary embodiment consistent with the present invention, a method 700 for accessing and presenting data in monitoring system 200 is provided. As illustrated in FIG. 7, method 700 may include presenting a first record set associated with at least one of a first part monitored by a monitoring system (such as monitoring system 200), a first location of the first part, and a first supplier of the first part (step 702). Referring to the exemplary embodiment of FIG. 4, the first record set may include parts, locations, suppliers, or any other associated information fetched according to a user data query entered in selection area 402. For example, FIG. 4 shows that the first record set includes a record with a first part P1, a first location L1, and a supplier S1. Portions or all of the first record set may be displayed in results area 404 as a current page. For example, results area 404 depicts a first record set including eight lines of supplier information. Moreover, method 700 may include fetching from one or more databases or storage devices (such as storage devices 216 and/or 218) a second record set before a data request from the user (step 704). The second record set may be associated with at least one of a second part monitored by monitoring system 200, a second location, and a second supplier. The second record set may include parts, locations, suppliers, or any other associated information. For example, the second record set may include additional parts, suppliers, and/or locations. Monitor system 200 may fetch the second record set over bus 212, network 214, or via any other communication mechanism. Monitor system 200 may fetch the second record set (step 704) at the same time or substantially in parallel with fetching or presenting the first record set (step 702). For example, monitor system may fetch the second record set from storage devices 216 and 218 while it is fetching or presenting the first record set, or immediately thereafter. The second record set may be information just before and/or after the information currently presented in results area 404, such as the previous and/or next eight lines (not shown) of supplier information. Furthermore, as illustrated in FIG. 7, method 700 may include presenting the second record set in response to a data request (step 706). The data request may be any user input (e.g., mouse click, keystroke(s), etc.) that the user provides to monitor system 200 to signal a desire to view additional data matching the user's data query. Presenting the second record set may include displaying portions or all of the second record in results area 404 as a previous line item or a next line item in the current page or as a previous or a next page. If results area 404 displays the first record set in a scrolling window format, then the data request may be in the form of a scroll command by a user operating a mouse, as shown in FIG. 4. Additionally or alternatively, the data request may be in the form of a next page command via a next button 406, a previous page command via a previous button 408, or any other suitable user interface input from the user. By way of example, in one exemplary embodiment, a user may wish to see all records pertaining to P1 (i.e., the selection criteria). The user may do this by entering a data query with his selection criteria into a selection area, such as the one illustrated in FIG. 5A. In response, system 200 (FIG. 2) may search for all records meeting the selection criteria (i.e., all records regarding P1). System 200 may determine, for example, that there are ten records on storage devices 216 and/or 218 that match the selection criteria, as illustrated in the exemplary embodiment of FIG. 8A. However, a results area may only have enough space to display a limited number of records, such as four records at a time. Hence, system 200 may only fetch the first four records 802 as a first record set from storage devices 216 and/or 218, and display them in the results area. At substantially the same time that the first four records are fetched and/or before the a user makes a data request for the next four records, system 200 may fetch the next four records 804 as a second record set from storage devices 216 and/or 218. When the user makes a data request (e.g., by clicking a next page button) to see the next four records 804, system 200 will already have the data ready and may instantly display records 804 with minimal delay, as shown in the exemplary embodiment of FIG. 8B. Records and information stored on storage devices 216 and/or 218 may constantly be in a state of flux. Anytime a user requests information matching his criteria, from storage devices 216 and/or 218, the information may quickly be outdated because it is being updated/changed even as the user is requesting and viewing the requested information. Hence, after system 200 fetches a second record set (step 704 in FIG. 7) from storage devices 216 and/or 218, the information in the second record set may become outdated by the time the user finishes viewing the first record set and makes a data request (e.g., clicks next page) to view the second record set. To address this problem, system 200 may maintain a time-stamp on the second record set, keep a timer to indicate the age of the second record set, and/or use any other mechanism to determine whether the second record set is outdated. If system 200 determines from the time-stamp or timer that the second record set is too old, system 200 may re-fetch the second record set from storage devices 216 and/or 218 and display the re-fetched second record set instead of displaying the outdated version that it had already fetched. System 200 may determine whether the second record set is outdated and re-fetch the second record set, when the user makes a data request to view the second record set. Even if the user does not make a data request to view the second record set, system 200 may determine whether the second record set is outdated and re-fetch the second record set, after a predetermined time period has elapsed or some other condition has occurred. For example, as discussed above for FIG. 8A, system 200 may fetch records 802 and 804 for the first and second record sets, respectively. However, if system 200 determines that the second record set has become outdated for some reason (e.g., a user views the first record set for a very long time before moving on to view the second record set on a next page), then when the user makes a data request to view the second record set, system 200 may re-fetch the second record set and display the re-fetched second record set instead of the previously fetched second record set. Of course, as system 200 is fetching the second record set, it may also fetch a third record set for the page of records following the second record set, in anticipation of the user's next data request (e.g., another next page command). In one exemplary embodiment, the first record set and second record set may be for the same fields of data, but the second record set is an updated version of the first record set. For example, as illustrated in FIG. 4, a user may request supplier information for parts P to Q. System 200 may determine that their are 40 records that match the user's selection criteria. System 200 may fetch only eight out of the 40 records as a first record set from memory 204, storage device 216, and/or storage device 218 because results area 404 can only display eight records at a time. However, it may be known that the first record set contains outdated data or that the first record set contains records that are regularly changed/updated. Hence, system 200 may also fetch a second record set, from storage devices 216 and/or 218, that contains an updated version of the records in the first record set. System 200 may fetch the second record set before the user makes a data request (e.g., click refresh button 410 in FIG. 4, etc.) to refresh the display. When the user decides to view the updated version of the records in the first record set, he may make a data request to refresh the display of the first record set with the second record set. In this manner, system 200 may provide a relatively quick response to the user's initial request for information by providing possibly outdated data from the first record set, and may again provide another quick response, when the user makes a data request to refresh the view of records from the first record set with updated versions from the second record set. As can be seen from the above, by fetching only a portion of the information matching a user's data query or given selection criteria and an additional portion expected to be accessed next by a user, monitor system 200 may present shortage parts information to the user in real-time. Also, although FIGS. 8A and 8B illustrate fetching and paging through rows of records, it should be understood that columns of records or any other organization of records may similarly be fetched to present shortage part information in real-time. Further, it should be understood that “real-time” as used herein does not only mean instantaneous real-time (e.g., immediate response by monitor system 200), but includes nearly instantaneous real-time, substantially real-time, and user-perceived real-time responses by monitor system 200. One of ordinary skill in the art will appreciate that features and principles of the present invention may be implemented in a computer readable medium (e.g., floppy disk, CD-ROM, storage device, etc.) containing instructions for a system, such as monitor system 200, to execute the instructions. The embodiments and aspects of the invention set forth above are only exemplary and explanatory. They are not restrictive of the invention as claimed. Other embodiments consistent with features and principles are included in the scope of the present invention. In the foregoing description, various features are grouped together for purposes of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects may lie in fewer than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this description, with each claim standing on its own as a separate embodiment of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>I. Technical Field The present invention generally relates to methods and systems for accessing and presenting data. More particularly, the invention relates to methods and systems in which data may be accessed from one or more databases in real-time to facilitate, for example, shortage monitoring in a supply chain management system. II. Background and Material Information In today's world of business, with global competition running rampant and consumer expectations ever-increasing, the efficiency of a business enterprise is becoming more important than ever. No longer will a consumer accept any delay in satisfying their mounting appetite for goods and services. They want their goods and services immediately, and in addition, demand the highest quality at the lowest cost. Hence, many businesses use supply chain management to control and optimize their production and cost. Supply chain management is a set of approaches and processes for efficiently integrating suppliers, manufacturers, warehouses, and stores, so that merchandise is produced and distributed at the right quantities, to the right locations, and at the right time, in order to minimize system-wide cost while satisfying service level requirements. A supply chain is a network of facilities and distribution options that procures and acquires material, processes and transforms the material into intermediate and finished products, and distributes the finished products to customers, whether intermediate or final ones. Supply chains exist both in manufacturing as well as in service organizations. Currently, technology is available to help manage a business's supply chain. However, as the needs of a large and growing business increase, more is expected for the business to stay competitive and fewer disruptions in the business's supply chain are tolerated. This is because any disruption can have extremely negative consequences on the business's reputation, market share, profitability, and ultimately, survivability. Particularly, shortages of parts or services in the supply chain can have immense impact on the efficiency of the business, including creating delays or even complete stoppages of the business's production. Accordingly, it would be beneficial to facilitate the management of supply chains, and in particular, facilitate real-time monitoring of parts or services in the supply chain. Moreover, it would be beneficial to access data in real-time to facilitate supply chain management including, for example, monitoring and managing supply shortages. | <SOH> SUMMARY OF THE INVENTION <EOH>Methods, systems, and articles of manufacture consistent with the present invention may facilitate the access of data. More particularly, methods, systems and articles of manufacture consistent with the invention facilitate data access, whereby the data may be accessed in real-time from one or more databases to perform, for example, shortage monitoring in a supply chain management system. One exemplary aspect of the invention relates to a method for presenting data in a monitoring system in real-time. The method may include: presenting a first record set; fetching a second record set before a data request; and presenting the second record set in response to the data request. The first record set may be associated with at least one of a first part monitored by the monitoring system, a first location of the first part, and a first supplier of the first part. The second record set may be associated with at least one of a second part monitored by the monitoring system, a second location of the first part, and a second supplier of the first part. Another exemplary aspect of the invention relates to a method for presenting data in real-time. The method may include presenting a first record of a plurality of records; fetching a second record from the plurality of records before receiving a data request for the second record; and presenting the fetched second record in response to receiving the data request. The first record may include at least one of a first part, a first location, and a first supplier. The second record may include at least one of a second part, a second location, and a second supplier. Another exemplary aspect of the invention relates to a method for presenting data in a monitoring system in real-time. The method may include: presenting a first record set in response to a data query in a monitoring system; fetching a second record set before receiving a data request; and presenting the second record set in response to receiving the data request. The second record set may contain a more current version of at least one record in the first record set. Another exemplary aspect of the invention relates to a monitoring system. The monitoring system may include a processor and a memory configured to perform a method for presenting data in real-time. Another exemplary aspect of the invention relates to a computer-readable medium containing instructions to configure a monitoring system to perform a method for presenting data in real-time. Another exemplary aspect of the invention relates to a user interface for presenting data in real-time. Additional aspects of the invention are set forth in the detailed description which follows or may be learned by practice of methods, systems, and articles of manufacture consistent with the present invention. It is understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. | 20040331 | 20101130 | 20051006 | 97037.0 | 0 | HASAN, SYED HAROON | METHODS AND SYSTEMS IN MONITORING TOOLS FOR EFFECTIVE DATA RETRIEVAL | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,100 | ACCEPTED | Method and system for imaging a volume using a three-dimensional spiral scan trajectory | A technique is provided for improving the depth resolution of tomosynthesis images. The technique provides for the use of spiral scan trajectories. The X-ray source may moved along the spiral scan trajectory, acquiring projection data at various locations on the trajectory which are offset in the z-direction, i.e., in a direction perpendicular to the detector. Projection data acquired at different positions in the z-direction may be used to generate three-dimensional, tomosynthesis images having improved depth resolution. | 1. A method for generating a three-dimensional image, comprising: moving an X-ray source along a spiral scan trajectory; acquiring projection data at a plurality of locations on the spiral scan trajectory, wherein projection data generated from different heights relative to a detector surface conveys greater depth information than projection data acquired along a two-dimensional trajectory; and generating a three-dimensional image from the projection data. 2. The method, as recited in claim 1, wherein the X-ray source is configured to move continuously along the spiral scan trajectory. 3. The method, as recited in claim 1, wherein the X-ray source is configured to move discontinuously along the spiral scan trajectory. 4. The method, as recited in claim 1, wherein the spiral scan trajectory comprises one of a spiral trajectory, a composite trajectory, a multi-planar-trajectory, and an arbitrary trajectory. 5. The method, as recited in claim 1, comprising: selecting the spiral scan trajectory based on a desired dosage for a region of interest. 6. The method, as recited in claim 1, comprising: adjusting an operating characteristic of the X-ray source based on the location on the spiral scan trajectory. 7. The method, as recited in claim 1, comprising: selecting a spiral scan trajectory based upon a two-dimensional trajectory having one or more desired characteristics. 8. A computer program, provided on one or more computer readable media, for generating a three-dimensional image, comprising: a routine for moving an X-ray source along a spiral scan trajectory; a routine for acquiring projection data at a plurality of locations on the spiral scan trajectory, wherein projection data generated from different heights relative to a detector surface conveys greater depth information than projection data acquired along a two-dimensional trajectory; and a routine for generating a three-dimensional image from the projection data. 9. The computer program, as recited in claim 8, wherein the routine for moving the X-ray source moves the X-ray source continuously along the spiral scan trajectory. 10. The computer program, as recited in claim 8, wherein the routine for moving the X-ray source moves the X-ray source discontinuously along the spiral scan trajectory. 11. The computer program, as recited in claim 8, wherein the spiral scan trajectory comprises one of a spiral trajectory, a composite trajectory, a multi-planar-trajectory, and an arbitrary trajectory. 12. The computer program, as recited in claim 8, comprising: a routine for selecting the spiral scan trajectory based on a desired dosage for a region of interest. 13. The computer program, as recited in claim 8, comprising: a routine for adjusting an operating characteristic of the X-ray source based on the location on the spiral scan trajectory. 14. The computer program, as recited in claim 8, comprising: a routine for selecting a spiral scan trajectory based upon a two-dimensional trajectory having one or more desired characteristics. 15. A tomosynthesis imaging system, comprising: means for moving an X-ray source along a spiral scan trajectory; means for acquiring projection data at a plurality of locations on the spiral scan trajectory, wherein projection data generated from different heights relative to a detector surface conveys greater depth information than projection data acquired along two-dimensional trajectory; and means for generating a three-dimensional image from the projection data. 16. A tomosynthesis imaging system, comprising: an X-ray source configured to emit a stream of radiation through a volume of interest at a plurality of locations along a spiral scan trajectory; a detector array comprising a plurality of detector elements, wherein each detector element may generate one or more signals in response to the respective streams of radiation and wherein the one or more signals generated in response to streams of radiation emitted at different heights relative to the detector convey greater depth information than projection data acquired along a two-dimensional trajectory; a system controller configured to control the X-ray source and to acquire the one or more signals from the plurality of detector elements; a computer system configured to receive the one or more signals and to generate a three-dimensional image from the one or more signals; and an operator workstation configured to display the rendered image. 17. The tomosynthesis imaging system, as recited in claim 16, wherein the X-ray source is configured to move continuously along the spiral scan trajectory. 18. The tomosynthesis imaging system, as recited in claim 16, wherein the X-ray source is configured to move discontinuously along the spiral scan trajectory. 19. The tomosynthesis imaging system, as recited in claim 16, wherein the spiral scan trajectory comprises one of a spiral trajectory, a composite trajectory, a multi-planar-trajectory, and an arbitrary trajectory. 20. The tomosynthesis imaging system, as recited in claim 16, wherein an operating characteristic of the X-ray source is adjusted based on the location of the X-ray source on the spiral scan trajectory. | BACKGROUND OF THE INVENTION The present invention relates generally to the field of medical imaging, and more specifically to the field of tomosynthesis. In particular, the present invention relates to the use of three-dimensional scan trajectories during acquisition of image data. Tomosynthesis is an imaging modality that may be used, in a medical context, to allow physicians and radiologists to non-invasively obtain three-dimensional representations of selected organs or tissues of a patient. In tomosynthesis, projection radiographs, conventionally known as X-ray images, are acquired at different angles relative to the patient. Typically, a limited number of projection radiographs are acquired over a relatively small angular range. The projections comprising the radiographs generally represent the line integrals of the attenuation coefficients along the respective X-ray paths through the patient and, therefore, convey useful data regarding internal structures. From the acquired projection radiographs, a three-dimensional representation of the imaged volume may be reconstructed. Typically, the reconstructed data set may be arranged in planar cross-sections, i.e., slices, of the volume at different heights, each slice being parallel to the plane of the X-ray detector. The reconstructed data set may be reviewed by a technologist or radiologist trained to generate a diagnosis or evaluation based on such data. In such a medical context, tomosynthesis may provide three-dimensional shape and location information of structures of interest as well as an increased conspicuity of the structures within the imaged volume. The quality of the three-dimensional rendering available for viewing may depend, in large part, on the quality of the acquired projection data. For objects that are small relative to the size of the detector, the quality of the projection data, in turn, is generally limited by the range of angles over which the projection data is acquired. Therefore, the quality of the acquired projections typically depends, at least in part, on the scan trajectory traveled by the X-ray source during acquisition of the projection image data. One-dimensional, i.e., linear scan trajectories, and two-dimensional, i.e., planar, scan trajectories yield a specific depth resolution, i.e., the resolution in the direction perpendicular to the detector surface, which is reflected in the subsequent three-dimensional rendering. In particular, for one-dimensional and two-dimensional scan trajectories, the depth information is defined by the scanning angles and is specific to each trajectory. Because depth resolution is limited by the available range of motion of the X-ray source, the depth resolution may not be as good as the resolution in the plane parallel to the detector surface. A technique for acquiring projection images during tomosynthesis that provides improved depth resolution may, therefore, be desirable. BRIEF DESCRIPTION OF THE INVENTION The present technique provides a novel approach to acquiring projection images during tomosynthesis. In particular, the present technique provides for the use of three-dimensional scan trajectories for use in the acquisition of tomosynthesis projection images. The depth resolution of three-dimensional images reconstructed from projection images acquired at different locations along the z-axis may be improved relative to similar images derived from projection data acquired using one and two-dimensional scan trajectories. In accordance with one aspect of the technique, a method is provided for generating a three-dimensional image. In accordance with the aspect, an X-ray source is moved along a three-dimensional trajectory. Projection data may be acquired at a plurality of locations on the three-dimensional trajectory. Projection data generated from different heights relative to a detector surface may convey greater depth information than projection data acquired along a two-dimensional trajectory. A three-dimensional may be generated from the projection data. Systems and computer programs that afford functionality of the type defined by these aspects are also provided by the present technique. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: FIG. 1 is a diagrammatical view of an exemplary imaging system in the form of a tomosynthesis imaging system for use in producing processed images, in accordance with aspects of the present technique; FIG. 2 depicts a spiral three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique; FIG. 3 depicts another spiral three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique; FIG. 4 depicts a composite spiral three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique; FIG. 5 depicts another composite spiral three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique; FIG. 6 depicts a step-and-shoot three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique; and FIG. 7 depicts an arbitrary three-dimensional scan trajectory for use in tomosynthesis, in accordance with aspects of the present technique. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS In the field of medical imaging, various imaging modalities may be employed to non-invasively examine and/or diagnose internal structures of a patient using various physical properties. One such modality is tomosynthesis imaging which utilizes a limited number of projection radiographs that are each acquired at a different angle relative to a patient. The projection radiographs may be combined to generate a set of data that provides three-dimensional context and structure for the volume of interest. Typically, the projection radiographs are generated using an X-ray source moving in a plane parallel to a detector. The X-ray source may move in one or two dimensions within the plane. The linear and/or planar movement of the X-ray source effectively limits the depth resolution that may be achieved in three-dimensional images reconstructed from the acquired projection data. The present technique is directed to the improvement of depth resolution by incorporating motion along the depth dimension into the scan trajectory traveled by the X-ray source. An example of a tomosynthesis imaging system 10 capable of acquiring and/or processing image data in accordance with the present technique is illustrated diagrammatically in FIG. 1. As depicted, the tomosynthesis imaging system 10 includes an X-ray source 12, such as an X-ray tube, and associated support and filtering components. The X-ray source 12 may be moved within a constrained region. As one of ordinary skill in the art will appreciate, the constrained region may be arcuate or otherwise three-dimensional. For simplicity, the constrained region is depicted and discussed herein as a cubic volume 14 within which the source 12 may move in three-dimensions, depicted in FIG. 1 as x and y dimensions, corresponding to the surface of a detector array 22, and a z dimension which is orthogonal to the x,y-plane. A stream of radiation 16 is emitted by the source 12 and passes into a region in which a subject, such as a human patient 18, is positioned. A portion of the radiation 20 passes through or around the subject and impacts the detector array, represented generally at reference numeral 22. The detector 22 is generally formed by a plurality of detector elements, generally corresponding to pixels, which produce electrical signals that represent the intensity of the incident X-rays. These signals are acquired and processed to reconstruct an image of the features within the subject. A collimator may also be present, which defines the size and shape of the X-ray beam 16 that emerges from the X-ray source 12. Source 12 is controlled by a system controller 24 which furnishes both power and control signals for tomosynthesis examination sequences. Moreover, detector 22 is coupled to the system controller 24, which commands acquisition of the signals generated by the detector 22. The system controller 24 may also execute various signal processing and filtration functions, such as for initial adjustment of dynamic ranges, interleaving of digital image data, and so forth. In general, the system controller 24 commands operation of the imaging system 10 to execute examination protocols and to acquire the resulting data. In the exemplary imaging system 10, the system controller 24 commands the movement of the source 12 within the volume 14 via a motor controller 26, which moves the source 12 relative to the patient 18 and the detector 22. In alternative implementations, the motor controller 26 may move the detector 22, or even the patient 18, instead of or in addition to the source 12. Additionally, the system controller 24 may include an X-ray controller 28 to control the activation and operation of the X-ray source 12. In particular, the X-ray controller 28 may be configured to provide power and timing signals to the X-ray source 12. By means of the motor controller 26 and X-ray controller 28, the system controller 24 may facilitate the acquisition of radiographic projections at various angles through the patient 18. The system controller 24 may also include a data acquisition system 30 in communication with the detector 22. The data acquisition system 30 typically receives data collected by readout electronics of the detector 22, such as sampled analog signals. The data acquisition system 30 may convert the data to digital signals suitable for processing by a processor-based system, such as a computer 36. The computer 36 is typically coupled to the system controller 24. The data collected by the data acquisition system 30 may be transmitted to the computer 36 for subsequent processing and reconstruction. For example, the data collected from the detector 22 may undergo pre-processing and calibration at the data acquisition system 30 and/or the computer 36 to condition the data to represent the line integrals of the attenuation coefficients of the scanned objects. The processed data, commonly called projections, may then be backprojected to formulate an image of the scanned area. Once reconstructed, the images produced by the system of FIG. 1 reveal an internal region of interest of the patient 18 which may be used for diagnosis, evaluation, and so forth. The computer 36 may comprise or communicate with memory circuitry that can store data processed by the computer 36 or data to be processed by the computer 36. It should be understood that any type of computer accessible memory device capable of storing the desired amount of data and/or code may be utilized by such an exemplary system 10. Moreover, the memory circuitry may comprise one or more memory devices, such as magnetic or optical devices, of similar or different types, which may be local and/or remote to the system 10. The memory circuitry may store data, processing parameters, and/or computer programs comprising one or more routines for performing the processes described herein. The computer 36 may also be adapted to control features enabled by the system controller 24, i.e., scanning operations and data acquisition. Furthermore, the computer 36 may be configured to receive commands and scanning parameters from an operator via an operator workstation 40 which may be equipped with a keyboard and/or other input devices. An operator may thereby control the system 10 via the operator workstation 40. Thus, the operator may observe reconstructed images and other data relevant to the system 10 from computer 36, initiate imaging, and so forth. A display 42 coupled to the operator workstation 40 may be utilized to observe the reconstructed images and to control imaging. Additionally, the images may also be printed by a printer 44 that may be coupled to the operator workstation 40. The display 42 and printer 44 may also be connected to the computer 36, either directly or via the operator workstation 40. Further, the operator workstation 40 may also be coupled to a picture archiving and communications system (PACS) 44. It should be noted that PACS 44 may be coupled to a remote system 46, radiology department information system (RIS), hospital information system (HIS) or to an internal or external network, so that others at different locations may gain access to the image and to the image data. It should be further noted that the computer 36 and operator workstation 40 may be coupled to other output devices that may include standard or special purpose computer monitors and associated processing circuitry. One or more operator workstations 40 may be further linked in the system for outputting system parameters, requesting examinations, viewing images, and so forth. In general, displays, printers, workstations, and similar devices supplied within the system may be local to the data acquisition components, or may be remote from these components, such as elsewhere within an institution or hospital, or in an entirely different location, linked to the image acquisition system via one or more configurable networks, such as the Internet, virtual private networks, and so forth. Once reconstructed and combined, the image data generated by the system of FIG. 1 reveals the three-dimensional relationship of internal features of the patient 18. The reconstructed three-dimensional image, however, may have an associated depth resolution, i.e., resolution in the z-dimension, that is less than that associated with the x,y-plane, which is generally a function of the properties of the detector array 22. In particular, the associated depth resolution may be unsuitable for the desired use or may otherwise detract from the accurate perception of depth in the three-dimensional image. The depth resolution of the three-dimensional image, as noted above, may largely be a function of the scan trajectory traveled by the X-ray source 12 during acquisition of the projection images. In particular, one-dimensional and two-dimensional scan trajectories, i.e., trajectories limited to the x,y-plane, may provide insufficient information to achieve higher depth resolutions. One possibility, therefore, is to utilize three-dimensional scan trajectories, herein referred to as spiral scan trajectories, during projection acquisition. Such a spiral scan trajectory would allow projection images of a region of interest to be acquired from different distances, thereby achieving different perspectives and potentially greater depth information. Three-dimensional images reconstructed from projections acquired along a spiral scan trajectory may, therefore, improve depth resolution in the resulting volume renderings. In particular, the depth resolution, as well as the in-plane resolution, of a region is affected by how the region is sampled in three-dimensions, i.e., by the spiral scan trajectory. Therefore, scan trajectories defined by only one or two dimensions, i.e., constant in the z-dimension, do not provide as much flexibility in obtaining the desired depth resolution as those which utilize all three dimensions. Furthermore, since X-ray intensity changes with the inverse squared distance from the X-ray source 12, spiral scan trajectories may provide a mechanism for dose management during the tomosynthesis imaging process. In particular, the motion of the source 12 in three dimensions provides greater flexibility in controlling the X-ray dose received by a patient 18 at any particular location. For example, a spiral scan trajectory may be configured or selected which provides relatively lower dosage to the region of interest while also maximizing the depth information obtained of the region of interest or the surrounding area. Similarly, the operation of the source 12 may be varied based upon the position of the source 12 on the spiral scan trajectory. For example, intensity, spectrum or collimation of the X-ray source 12 may be varied based on the position of the X-ray source 12, the generator power, and/or the collimator capabilities. Selection of a spiral scan trajectory may be based on various factors, including customization based on region of interest, desired dose, desired X-ray intensity, and so forth. Though the term spiral scan trajectory is used herein, it is to be understood that the actual trajectory traced by the X-ray source may be any three-dimensional scan trajectory, including arbitrary three-dimensional scan trajectories. The term spiral scan trajectory, therefore, encompasses not only spiral motion but also other curved and circular motion as well as linear and arbitrary motion. Furthermore, a spiral scan trajectory may be based on a one or two dimensional scan trajectory with certain desirable characteristics. For example, a two-dimensional scan trajectory that achieves desirable results, such as improved data completeness, may be modified and further enhanced by adding a z-direction component to generate a suitable spiral scan trajectory. The distance traveled by the source 12 in the z-direction may vary depending on the application, desired scan trajectory, the region of interest, and/or patient specific factors. The motion of the X-ray source 12 may be continuous, such that the X-ray source 12 remains in motion along the spiral scan trajectory, though the velocity of the X-ray source 12 may vary or may be constant along the spiral scan trajectory. Alternatively, the motion of the X-ray source 12 may be discontinuous, such that the X-ray source 12 intermittently stops at different points on the spiral scan trajectory, such as during the emission of X-rays. For example, FIGS. 2-7 depict possible scan trajectories that may produce desirable depth resolutions. FIG. 2, for example, depicts a first spiral trajectory 50 based on spiral motion that originates from the point closest to the patient 18 and unwinds in a spiral pattern (in the x,y-plane) as the source 12 moves away from the patient 18 in the z-direction. Conversely, FIG. 3 depicts a second spiral trajectory 51 based on a spiral motion that originates at the point farthest from the patient 18 and unwinds in a spiral pattern as the source 12 moves toward the patient 18 in the z-direction. The spiral trajectories 50, 51 depicted in FIGS. 2 and 3 may be combined, as depicted in FIG. 4, to generate a first composite trajectory 52 that originates at the point farthest from the patient 18 and unwinds as the source 12 moves toward the patient 18 in the z-direction. At a central point, however, the source 12 winds inward as the source 12 moves to the point closest to the patient 18 in the z-direction. Alternately, as one of ordinary skill in the art will appreciate, the spiral trajectories 50, 51 may be combined in an alternate fashion to yield a second composite trajectory 53, as depicted in FIG. 5, that originates at the point farthest from the patient 18 and winds inward as the source 12 moves toward the patient 18 in the z-direction. At a central point, however, the source 12 unwinds as the source 12 moves to the point closest to the patient 18 in the z-direction. The spiral and composite trajectories 50, 51, 52, 53 described herein may possess various desirable attributes. For example, such trajectories may minimize data incompleteness, thereby improving image quality. In addition to these benefits, the z-direction component to the trajectories allows for better depth resolution in the three-dimensional images derived from projection data acquired at intervals along such spiral and composite trajectories 50, 51, 52, 53. While scan trajectories incorporating spiral motion represent one possibility, other three-dimensional scan trajectories are also possible. For example, multi-planar trajectories 54 may be desirable in some circumstances. Such multi-planar trajectories 54 may involve moving the X-ray source during acquisition in a two-dimensional at a first distance in the z-direction from the patient 18. The source 12 may then be moved toward or away from the patient 18 to a new location on the z-axis, where the source 12 is moved in a two-dimensional profile during acquisition at the new z-location. For example, referring to FIG. 6, the two-dimensional profile depicted is a circle that increases in radius as the distance from the patient 18 to the source 12 increases. As one of ordinary skill in the art will appreciate, the shape of the two-dimensional profile may change or remain the same at different planes of the multi-planar trajectory 54. Likewise, the size of the two-dimensional profile may change or remain the same at different planes of the multi-planar trajectory 54. While FIGS. 2-6 depict three-dimensional trajectories having a geometric or symmetric regularity, the three-dimensional trajectory may instead be essentially arbitrary in character, based on the application or other considerations. For example, the three-dimensional trajectory may be an arbitrary trajectory 56, such as a zig-zag trajectory, as depicted in FIG. 7. Such an arbitrary trajectory 56 may range over the full height of the detector 22 but only a portion of the width of the detector 22, the full width of the detector 22 and a multiple of the height of the detector 22, or the full height of the detector 22 and a multiple of the width of the detector 22. Other arbitrary trajectories are of course possible, however, based on the demands of the application and/or the patient. As one of ordinary skill in the art will readily appreciate, the preceding examples are merely illustrative of the present techniques. Other three-dimensional scan trajectories than those discussed herein may be employed which result in improvement of depth resolution of the resulting three-dimensional images. The present technique, therefore, encompasses other three-dimensional trajectories providing improvement in depth resolution, not merely those discussed herein. The invention may be susceptible to various modifications and alternative forms, and specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates generally to the field of medical imaging, and more specifically to the field of tomosynthesis. In particular, the present invention relates to the use of three-dimensional scan trajectories during acquisition of image data. Tomosynthesis is an imaging modality that may be used, in a medical context, to allow physicians and radiologists to non-invasively obtain three-dimensional representations of selected organs or tissues of a patient. In tomosynthesis, projection radiographs, conventionally known as X-ray images, are acquired at different angles relative to the patient. Typically, a limited number of projection radiographs are acquired over a relatively small angular range. The projections comprising the radiographs generally represent the line integrals of the attenuation coefficients along the respective X-ray paths through the patient and, therefore, convey useful data regarding internal structures. From the acquired projection radiographs, a three-dimensional representation of the imaged volume may be reconstructed. Typically, the reconstructed data set may be arranged in planar cross-sections, i.e., slices, of the volume at different heights, each slice being parallel to the plane of the X-ray detector. The reconstructed data set may be reviewed by a technologist or radiologist trained to generate a diagnosis or evaluation based on such data. In such a medical context, tomosynthesis may provide three-dimensional shape and location information of structures of interest as well as an increased conspicuity of the structures within the imaged volume. The quality of the three-dimensional rendering available for viewing may depend, in large part, on the quality of the acquired projection data. For objects that are small relative to the size of the detector, the quality of the projection data, in turn, is generally limited by the range of angles over which the projection data is acquired. Therefore, the quality of the acquired projections typically depends, at least in part, on the scan trajectory traveled by the X-ray source during acquisition of the projection image data. One-dimensional, i.e., linear scan trajectories, and two-dimensional, i.e., planar, scan trajectories yield a specific depth resolution, i.e., the resolution in the direction perpendicular to the detector surface, which is reflected in the subsequent three-dimensional rendering. In particular, for one-dimensional and two-dimensional scan trajectories, the depth information is defined by the scanning angles and is specific to each trajectory. Because depth resolution is limited by the available range of motion of the X-ray source, the depth resolution may not be as good as the resolution in the plane parallel to the detector surface. A technique for acquiring projection images during tomosynthesis that provides improved depth resolution may, therefore, be desirable. | <SOH> BRIEF DESCRIPTION OF THE INVENTION <EOH>The present technique provides a novel approach to acquiring projection images during tomosynthesis. In particular, the present technique provides for the use of three-dimensional scan trajectories for use in the acquisition of tomosynthesis projection images. The depth resolution of three-dimensional images reconstructed from projection images acquired at different locations along the z-axis may be improved relative to similar images derived from projection data acquired using one and two-dimensional scan trajectories. In accordance with one aspect of the technique, a method is provided for generating a three-dimensional image. In accordance with the aspect, an X-ray source is moved along a three-dimensional trajectory. Projection data may be acquired at a plurality of locations on the three-dimensional trajectory. Projection data generated from different heights relative to a detector surface may convey greater depth information than projection data acquired along a two-dimensional trajectory. A three-dimensional may be generated from the projection data. Systems and computer programs that afford functionality of the type defined by these aspects are also provided by the present technique. | 20040330 | 20060516 | 20051013 | 70403.0 | 0 | BRUCE, DAVID VERNON | METHOD AND SYSTEM FOR IMAGING A VOLUME USING A THREE-DIMENSIONAL SPIRAL SCAN TRAJECTORY | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,111 | ACCEPTED | High brightness diffuser | The present invention is to provide a solution for fabricating a light diffusing sheet-like device capable of emitting light with superior brightness, that is a high brightness diffuser. The high brightness diffuser mainly comprises at least two light diffusing pieces with ridge-shape structure arranged thereon, which can be either convex or concave. The convex ridge-shape structure is consisted of a plurality of large convex ridges and a plurality of small convex ridges, which are associated with a ridgeline existing in between two adjacent ridges where the large ridge and small ridge are interlace-arranged, and the ridges along with the associated ridgelines can be longitudinally extended to the same direction. Likewise, The concave ridge-shape structure is constituted the same way as the convex ridge-shape structure is, but is consisted of concave ridges. The high brightness diffuser is fabricated by stacking up the two light diffusing pieces and enabling an included angle to be formed between the two ridge-extending directions of the two light diffusing pieces. Through the embodiment of the present invention, a high brightness diffuser with reduced thickness capable of emitting light of superior brightness and of wide-angle uniformity can be fabricated, and thus can be applied in a rear projection module. | 1. A high brightness diffuser, comprising: a convex light diffusing piece with ridge-shape structure arranged on a surface thereof, being consisted of a plurality of large convex ridges and a plurality of small convex ridges, wherein, each of the convex ridges has a ridgeline, and the large ridge and small ridge are interlace-arranged, and the plural ridges along with the associated ridgelines are extending toward a same direction; a concave light diffusing piece with ridge-shape structure arranged on a surface thereof, being consisted of a plurality of concave ridges associated with a ridgeline existing in between two adjacent ridges, wherein the plural ridges along with the associated ridgelines are extending toward a same direction; and wherein, the two light diffusing pieces are stacked up by plastering the surface with ridge-shape structure of the convex light diffusing piece on the surface without ridge-shape structure of the concave light diffusing piece, and enabling an included angle to be formed between the two ridge-extending directions of the two light diffusing pieces. 2. The high brightness diffuser of claim 1, wherein the included angle is 45°. 3. The high brightness diffuser of claim 1, wherein, with an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent large ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. 4. The high brightness diffuser of claim 1, wherein, with an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent small ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. 5. The high brightness diffuser of claim 1, wherein, with an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent concave ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. 6. The high brightness diffuser of claim 1, wherein both the convex light diffusing piece and the concave light diffusing piece further comprise respectively a substrate, a ridge-shaped layer and a diffusion layer consisted of a thin transparent layer having a rugged external surface and numerous light diffusing particles uniformly dispersed within the thin transparent layer, and the substrate is sandwiched in between the ridge-shaped layer and the diffusion layer. 7. The high brightness diffuser of claim 1, wherein both the convex light diffusing piece and the concave light diffusing piece further comprise respectively a substrate, a ridge-shaped layer and a diffusion layer consisted of a thin transparent layer having a rugged external surface facing toward the ridge-shape layer and numerous light diffusing particles uniformly dispersed within the thin transparent layer, and the diffusion layer is sandwiched in between the ridge-shaped layer and the substrate. 8. A high brightness diffuser, comprising: two convex light diffusing piece with ridge-shape structure arranged on a surface thereof, being consisted of a plurality of large convex ridges and a plurality of small convex ridges, wherein, each of the convex ridges has a ridgeline, and the large ridge and small ridge are interlace-arranged, and the plural ridges along with the associated ridgelines are extending toward a same direction; wherein, the two convex light diffusing pieces are stacked up by plastering the surface with ridge-shape structure of the convex light diffusing piece on the surface without ridge-shape structure of the other convex light diffusing piece, and enabling an included angle to be formed between the two ridge-extending directions of the two convex light diffusing pieces. 9. The high brightness diffuser of claim 8, wherein the incluided angle is 8.5°. 10. The high brightness diffuser of claim 8, wherein, with an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent large ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. 11. The high brightness diffuser of claim 8, wherein, with an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent small ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. 12. The high brightness diffuser of claim 8, wherein the convex light diffusing piece further comprises a substrate, a ridge-shaped layer and a diffusion layer consisted of a thin transparent layer having a rugged external surface and numerous light diffusing particles uniformly dispersed within the thin transparent layer, and the substrate is sandwiched in between the ridge-shaped layer and the diffusion layer. 13. The high brightness diffuser of claim 1, wherein the convex light diffusing piece further comprises a substrate, a ridge-shaped layer and a diffusion layer consisted of a thin transparent layer having a rugged external surface facing toward the ridge-shape layer and numerous light diffusing particles uniformly dispersed within the thin transparent layer, and the diffusion layer is sandwiched in between the ridge-shaped layer and the substrate. | 1. FIELD OF THE INVENTION This invention relates to a kind of sheet-like light diffusing device, capable of emitting light of superior brightness, that is, a high brightness diffuser, and more particularly to a high brightness diffuser consisted of at least two overlapping light diffusing pieces with ridge-shape structure arranged thereon. 2. BACKGROUND OF THE INVENTION Light diffusers adopted in an ordinary large-scale display (e.g. rear projection screen and large-scale liquid crystal display) are commonly located at the outmost layer of the screen, thereby enabling the light emitted with good output brightness and wide-angle uniformity. FIG. 1 shows the photometric performance pertaining to various kinds of similar products available in the current market. Curve A in FIG. 1 represents the photometric performance of the light diffuser disclosed in U.S. Pat. No. 6,327,083, “REAR PROJECTION SCREEN WITH REDUCED SPECKLE”, curves B and C respectively represents the photometric performance of two different conventional light diffusers, and curve D represents the photometric performance of a rear projection light diffuser. As seen in FIG. 1 that the foregoing diffuser can only provide a good photometric performance within the 60° front viewing angle at the audience side of the projection screen, whereas the brightness outside the 60° front viewing angle is considerably reduced. Consequently, the viewer sitting in front of the screen would experience a great brightness disparity when his viewing cover wide side angles. Therefore, the large-scale display screen fabricated by the prior art technique is unable to deliver a uniform illuminance required by the wide-angle viewing. In addition, for those light diffusers fabricated by the prior art techniques, thick structure of approximately 1 mm is normally needed to boost the light diffusion efficiency when they are used in the large-scale display screen. The design as such would either reduce the brightness output or fail to meet the aforementioned requirement for wide-angle viewing. If the thickness of the light diffusing sheet member can be made thinner, said element can be used in the modern rear projection module. FIG. 2 represents a schematic drawing of the diffuser disclosed in the U.S. Pat. No. 6,327,083. As seen in FIG. 1, the diffuser 40 is made up of a front lenticular lens array 40a having unique microstructure design, a bulk region 48, and a clear region 49. The lenticular lens array 40a is composed of a plurality of concave elements 42 and convex elements 44 aligned orderly, wherein the concave element 42 is filled with light diffusing particles 46. Close examination at the structure of concave element reveals a depression of concave shape 441 and a wavy contour of varying flatness. The drawback of aforementioned invention is that the lenticules array 40a designed as such would require fabrication technologies involving semiconductor manufacturing and various sophisticated mechanical processing techniques, thus resulting in poor manufacturability and high manufacturing cost. Furthermore, despite having the advantage of being able to reduce the speckle patterns, as is claimed in this prior art, the aforementioned diffusion means is incapable of emitting light with superior brightness and good wide-angle uniformity. SUMMARY OF THE INVENTION In light of the drawback associated with the prior art, the primary object of the present invention is to provide a high brightness diffuser consisted of at least two overlapping light diffusing pieces with ridge-shape structure arranged thereon, so that the high brightness diffuser with reduced thickness capable of emitting light of superior brightness and of wide-angle uniformity can be fabricated, and thus can be applied in a rear projection module. The secondary object of the present invention is to provide a solution for fabricating a high brightness diffuser comprising at least two light diffusing sheets, and each light diffusing sheet further comprising a substrate, a ridge-shaped layer and a diffusion layer, wherein the diffusion layer includes a transparent region and numerous light-diffusing particles uniformly dispersed inside the transparent region, and the substrate having a rugged external surface is sandwiched in between the ridge-shaped layer and the diffusion layer. Alternatively, the diffusion layer is placed in between the ridge-shaped layer and the substrate and the transparent region of the diffusion layer has a rugged surface facing toward the ridge-shaped layer. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is the photometric performance of various light diffusers. FIG. 2 is a schematic diagram illustrating a conventional diffuser. FIG. 3 is a 3D diagram of the convex diffusing piece according to the present invention. FIG. 4 is a 3D diagram of the concave diffusing piece according to the present invention. FIG. 5 is a 3D diagram depicting the compound light diffuser that is formed by combining the convex diffusing piece of FIG. 3 and the concave diffusing piece of FIG. 4. FIG. 5A is the A-A sectional view of FIG. 5. FIG. 6 is a 3D diagram depicting the compound light diffuser that is formed by stacking two convex diffusing piece of FIG. 3. FIG. 6A is the A-A sectional view of FIG. 6. FIG. 7 is a 3D diagram of the convex diffusing piece according to another embodiment of the present invention. FIG. 8 is a 3D diagram of the concave diffusing piece according to another embodiment of the present invention. FIG. 9 is a 3D diagram depicting the compound light diffuser that is formed by combining the convex diffusing piece of FIG. 7 and the concave diffusing piece of FIG. 8. FIG. 9A is the A-A sectional view of FIG. 9. FIG. 10 is a 3D diagram depicting the compound light diffuser that is formed by stacking two convex diffusing piece of FIG. 7. FIG. 10A is the A-A sectional view of FIG. 10. FIG. 11 is the photometric performance of the light diffusers embodying the present invention as represented in FIGS. 5 and 6 and those embodying the prior art. DESCRIPTION OF THE PREFERRED EMBODIMENT For your esteemed members of reviewing committee to further understand and recognize the fulfilled functions and structural characteristics of the invention, several preferable embodiments cooperating with detailed description are presented as the follows. FIG. 3 shows a convex diffusing piece according to the present invention. The convex diffusing piece 10 comprises a substrate 11, a ridge-shaped layer 12 and a diffusion layer 13. The substrate 11, ridge-shaped layer 12 and diffusion layer 13 all are transparent. As seen in FIG. 3, the substrate is sandwiched in between and the diffusion layer 13 and the ridge-shaped layer 12. The ridge-shaped layer 12 has a plurality of large convex ridges 121 and small convex ridges arranged thereon where the large convex ridges 121 is disposed immediately next to its smaller counterpart 122, and all of these ridges are parallel to the X-axis as shown in FIG. 3. The large convex ridges 121 has a ridgeline 1211 associated with it. With an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent large ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. In addition, the small convex ridges 122 has a ridgeline 1221 associated with it. With an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent small ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. The diffusion layer 13 is made up with a transparent thin layer 131 and numerous light-diffusing particles 132, which are uniformly dispersed within the transparent layer 131. One side of said transparent layer has a rugged surface, and the sizes of the diffusion particles 132 may range from several tens of nanometers to several units of micrometers. The light-diffusing particles 132 may have the shapes that include but not limited to sphere, oval, cylinder or other polyhedrons. In order to reduce the amount of light absorbed during diffusion, the chemical composition of the light diffusion particles 132 may include those materials having zero extinction coefficient substantially equal to zero, such as TiO2, SiO2, BaSO4, MgO2 or ZnS. FIG. 4 shows a concave diffusing piece according to the present invention. The concave diffusing piece 20 comprises a substrate 21, a ridge-shaped layer 22 and a diffusion layer 23. The substrate 21, ridge-shaped layer 22 and diffusion layer 23 all are transparent. As seen in FIG. 4, the substrate 21 is sandwiched in between the ridge-shaped layer 22 and the diffusion layer 23. The ridge-shaped layer 22 has a plurality of concave ridges 221 arranged thereon. Between every two concave ridge, there has a ridgeline 2211. With an inter-ridge distance being defined as the distance between the ridgelines 2211 of the two adjacent concave ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. Each concave ridge along with its ridgeline have an extension line parallel to the X′-axis, where the X′-axis and aforementioned X-axis makes an included angle of 45°. The diffusion layer 23 is composed with the thin transparent layer 231 and the light-diffusing particles 232 uniformly dispersed within the transparent layer 231. The transparent layer 231 has a rugged surface, and the sizes of the diffusion particles 232 may range from several tens of nanometers to several units of micrometers. The light diffusing particles 232 may have the shapes that include but not limited to spheres, ovals, cylinders or other polyhedrons. In order to reduce the amount of light absorbed during diffusion, the chemical composition of the light diffusion particles 232 may include those materials having zero extinction coefficient zero, such as TiO2, SiO2, BaSO4, MgO2 or ZnS. Please refer to FIG. 5 and FIG. 5A, where the convex light diffusing piece 10 is laid intimately over the top of the concave light diffusing piece 20. The convex light diffusion piece 10 and the concave light diffusing piece 20 are joined together such that the rugged surface of the diffusion layer 13 faces upward and the side with the convex ridges associated with the ridge-shaped layer 12 faces downward. The inter-ridge distance of the two adjacent large ridges 121 is 60 nanometers and its ridge's height is 25 nanometers. The inter-ridge distance of two adjacent small ridges 122 is 60 nanometers and its ridge's height is 10 nanometers. Moreover, the convex ridges extend longitudinally parallel to the X-axis direction as shown in FIG. 5. The substrate 11 is 100 nanometers thick. Furthermore, the rugged surface of the diffusion layer 23 of the concave light diffusing piece 20 face upward, while the concave ridges 221 associated with the ridge-shaped layer 22 faces downward. The inter-ridge distance of two adjacent concave ridges is 60 nanometers and the ridge's height is 20 nanometers. Each concave ridge is extended parallel to the X′-axis, where X′-axis and X-axis makes a included angle of 45°. The substrate 21 is 100 nanometers thick. The convex light diffusing piece 10 and the concave light diffusing piece 20 can be joined onto each other intimately, thereby forming a high brightness diffuser. To facilitate joining the convex light diffusing piece 10 onto the concave light diffusing piece 20 with no joining material used, static electricity can be applied onto the rugged surface associated with the diffusion layer 23 such that the joining of the convex light diffusing piece 10 and the concave light diffusing piece 20 can be accomplished in a vacuum environment. Another embodiment of the present invention is shown in FIGS. 6 and 6A, wherein two convex light diffusing pieces 10 and 10a are paired up to form another high brightness diffuser. The two convex diffusing pieces 10 and 10a are joined together with one piece laid intimately over the top of the other. The convex light diffusing pieces 10 and 10a are configured such that the rugged surface of the diffusion layer 13 of the convex light diffusing piece 10 located at the upper deck faces upward and the ridges associated with the ridge-shaped layer 12 faces downward. The inter-ridge distance of the two adjacent large ridges 121 is 60 nanometers and its ridge's height is 25 nanometers, whereas the inter-ridge distance of two adjacent small ridges 122 is 60 nanometers and its ridge's height is 10 nanometers. Moreover, both the large ridges 121 and the small ridges 122 extend longitudinally in the X-axis direction. The substrate 11a is 100 nanometers thick. The rugged surface associated with the diffusion layer 13a of the convex light diffusing piece 10a located at the lower deck faces upward, whereas the ridges associated with the ridge-shaped layer 12a faces downward. The inter-ridge distance is 60 nanometers and the ridge's height is 20 nanometers. The substrate 11a is 100 nanometers thick. The present embodiment has the characteristics that the large ridges 121a of the lowest layer of this light diffusing piece 10a and their associated longitudinal extension lines are parallel to the X′ direction, where X′-axis and X-axis makes an included angle of 8.5°. An intimate joining of two light diffusion pieces 10 and 10a can form a light diffuser capable of emitting light of superior brightness. The intimate joining can be accomplished through the application of static electricity on the rugged surface 13a in a vacuum environment, using no joining materials. FIG. 7 shows another convex diffusing piece according to the present invention. The convex diffusing piece 10bb comprises a substrate 11, a ridge-shaped layer 12b and a diffusion layer 13b. The substrate 11b, ridge-shaped layer 12b and diffusion layer 13b all are transparent. As seen in FIG. 7, the diffusion layer 13b is sandwiched in between the substrate 11 and the ridge-shaped layer 12b. The ridge-shaped layer 12b has a plurality of large convex ridges 121b and small convex ridges arranged thereon where the large convex ridges 121b is disposed immediately next to its smaller counterpart 122b, and all of these ridges are parallel to the X-axis as shown in FIG. 7. The large convex ridges 121b has a ridgeline 1211b associated with it. With an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent large ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. In addition, the small convex ridges 122b has a ridgeline 1221b associated with it. With an inter-ridge distance being defined as the distance between the ridgelines of the two adjacent small ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. The diffusion layer 13b is made up with a transparent thin layer 131b and numerous light-diffusing particles 132b, which are uniformly dispersed within the transparent layer 131b. One side of said transparent layer has a rugged surface, and the sizes of the diffusion particles 132b may range from several tens of nanometers to several units of micrometers. The light-diffusing particles 132b may have the shapes that include but not limited to sphere, oval, cylinder or other polyhedrons. In order to reduce the amount of light absorbed during diffusion, the chemical composition of the light diffusion particles 132b may include those materials having zero extinction coefficient substantially equal to zero, such as TiO2, SiO2, BaSO4, MgO2 or ZnS. FIG. 8 shows a concave diffusing piece according to the present invention. The concave diffusing piece 20b comprises a substrate 21b, a ridge-shaped layer 22b and a diffusion layer 23b. The substrate 21b, ridge-shaped layer 22b and diffusion layer 23b all are transparent. As seen in FIG. 8, the diffusion layer 23b is sandwiched in between the substrate 21b and the ridge-shaped layer 22b. The ridge-shaped layer 22b has a plurality of concave ridges 221b arranged thereon. Between every two concave ridge, there has a ridgeline 2211b. With an inter-ridge distance being defined as the distance between the ridgelines 2211b of the two adjacent concave ridges, and a ridge height being defined as the difference of altitude between the ridgeline and the line separating the large ridge and the small ridge, the inter-ridge distances are equal to each other and the ridge heights are equal to each other. Each concave ridge along with its ridgeline have an extension line parallel to the X′-axis, where the X′-axis and aforementioned X-axis makes an included angle of 45°. The diffusion layer 23b is composed with the thin transparent layer 231b and the light-diffusing particles 232b uniformly dispersed within the transparent layer 231b. The transparent layer 231b has a rugged surface, and the sizes of the diffusion particles 232b may range from several tens of nanometers to several units of micrometers. The light diffusing particles 232b may have the shapes that include but not limited to spheres, ovals, cylinders or other polyhedrons. In order to reduce the amount of light absorbed during diffusion, the chemical composition of the light diffusion particles 232b may include those materials having zero extinction coefficient zero, such as TiO2, SiO2, BaSO4, MgO2 or ZnS. Please refer to FIG. 9 and FIG. 9A, where the convex light diffusing piece 10b is laid intimately over the top of the concave light diffusing piece 20b. The convex light diffusion piece 10b and the concave light diffusing piece 20b are joined together such that the rugged surface of the diffusion layer 13b faces upward and the side with the convex ridges associated with the ridge-shaped layer 12b faces downward. The inter-ridge distance of the two adjacent large ridges 121b is 60 nanometers and its ridge's height is 25 nanometers. The inter-ridge distance of two adjacent small ridges 122b is 60 nanometers and its ridge's height is 10 nanometers. Moreover, the convex ridges extend longitudinally parallel to the X-axis direction as shown in FIG. 5. The substrate 11b is 100 nanometers thick. Furthermore, the rugged surface of the diffusion layer 23b of the concave light diffusing piece 20b face upward, while the concave ridges 221b associated with the ridge-shaped layer 22b faces downward. The inter-ridge distance of two adjacent concave ridges is 60 nanometers and the ridge's height is 20 nanometers. Each concave ridge is extended parallel to the X′-axis, where X′-axis and X-axis makes a included angle of 45°. The substrate 21b is 100 nanometers thick. The convex light diffusing piece 10b and the concave light diffusing piece 20b can be joined onto each other intimately, thereby forming a high brightness diffuser. To facilitate joining the convex light diffusing piece 10b onto the concave light diffusing piece 20b with no joining material used, static electricity can be applied onto the rugged surface associated with the diffusion layer 23b such that the joining of the convex light diffusing piece 10b and the concave light diffusing piece 20b can be accomplished in a vacuum environment. Another embodiment of the present invention is shown in FIGS. 10 and 10A, wherein two convex light diffusing pieces 10b and 10c are paired up to form another high brightness diffuser. The two convex diffusing pieces 10c and 10c are joined together with one piece laid intimately over the top of the other. The convex light diffusing pieces 10b and 10c are configured such that the rugged surface of the diffusion layer 13b of the convex light diffusing piece 10b located at the upper deck faces upward and the ridges associated with the ridge-shaped layer 12b faces downward. The inter-ridge distance of the two adjacent large ridges 121b is 60 nanometers and its ridge's height is 25 nanometers, whereas the inter-ridge distance of two adjacent small ridges 122b is 60 nanometers and its ridge's height is 10 nanometers. Moreover, both the large ridges 121b and the small ridges 122b extend longitudinally in the X-axis direction. The substrate 11b is 100 nanometers thick. The rugged surface associated with the diffusion layer 13c of the convex light diffusing piece 10c located at the lower deck faces upward, whereas the ridges associated with the ridge-shaped layer 12c faces downward. The inter-ridge distance is 60 nanometers and the ridge's height is 20 nanometers. The substrate 11c is 100 nanometers thick. The present embodiment has the characteristics that the large ridges 121c of the lowest layer of this light diffusing piece 10c and their associated longitudinal extension lines are parallel to the X′ direction, where X′-axis and X-axis makes an included angle of 8.5°. An intimate joining of two light diffusion pieces 10b and 10c can form a light diffuser capable of emitting light of superior brightness. The intimate joining can be accomplished through the application of static electricity on the rugged surface of the diffusion layer 13c in a vacuum environment, using no joining materials FIG. 11 shows the brightness performance with respect to viewing angle for the embodiments detailed in FIGS. 5 and 6 of the present invention and for those embodiments representing the prior art. In FIG. 11, Curve A represents the brightness performance of the light diffuser disclosed in U.S. Pat. No. 6,327,083. Similarly, Curves B and C represent the brightness performance of light diffusers employing the prior art, while Curve D represents the brightness performance of a light diffuser of a rear projection screen. Furthermore in FIG. 11, Curve E represents the brightness performance of a convex type diffuser 10 and a concave type diffuser 20 detailed in FIG. 5, and Curve F represents the compound light diffuser formed by laying double convex type diffusion pieces 10 and 10a over each other. From FIG. 11, it is known that better performance of brightness of light diffusers embodying the prior art as represented by Curves A, B, C and D can only be realized within the 60° front viewing angle, whereas the brightness beyond the center 60° front viewing angle is considerably reduced. However, the brightness of the light diffuser embodying the present invention as represented by Curves E and F is evenly spread over the center 80° of the front viewing angle, and thus has the merit of high output brightness plus wide-angle uniformity. This is an advantage, which can not be realized by the light diffusers embodying the prior art. The light diffuser embodying the present invention can not only be used in a large-scale screen, but can also be utilized in a rear projection module due to its small size, which is about one quarter the size of the prior-art diffusers. Besides, the light diffuser embodying the present invention can form different kinds of diffusers that have different optical characteristics through various combinations of the convex type diffuser and the concave type diffuser to meet different products' requirements. In summary, the present invention has the following the merits: 1. Great brightness output, 2. Wide-angle brightness uniformity 3. Thinned structure 4. Joint with shielding effect 5. Flexible structural variation to meet various product requirements While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention. | <SOH> 2. BACKGROUND OF THE INVENTION <EOH>Light diffusers adopted in an ordinary large-scale display (e.g. rear projection screen and large-scale liquid crystal display) are commonly located at the outmost layer of the screen, thereby enabling the light emitted with good output brightness and wide-angle uniformity. FIG. 1 shows the photometric performance pertaining to various kinds of similar products available in the current market. Curve A in FIG. 1 represents the photometric performance of the light diffuser disclosed in U.S. Pat. No. 6,327,083, “REAR PROJECTION SCREEN WITH REDUCED SPECKLE”, curves B and C respectively represents the photometric performance of two different conventional light diffusers, and curve D represents the photometric performance of a rear projection light diffuser. As seen in FIG. 1 that the foregoing diffuser can only provide a good photometric performance within the 60° front viewing angle at the audience side of the projection screen, whereas the brightness outside the 60° front viewing angle is considerably reduced. Consequently, the viewer sitting in front of the screen would experience a great brightness disparity when his viewing cover wide side angles. Therefore, the large-scale display screen fabricated by the prior art technique is unable to deliver a uniform illuminance required by the wide-angle viewing. In addition, for those light diffusers fabricated by the prior art techniques, thick structure of approximately 1 mm is normally needed to boost the light diffusion efficiency when they are used in the large-scale display screen. The design as such would either reduce the brightness output or fail to meet the aforementioned requirement for wide-angle viewing. If the thickness of the light diffusing sheet member can be made thinner, said element can be used in the modern rear projection module. FIG. 2 represents a schematic drawing of the diffuser disclosed in the U.S. Pat. No. 6,327,083. As seen in FIG. 1 , the diffuser 40 is made up of a front lenticular lens array 40 a having unique microstructure design, a bulk region 48 , and a clear region 49 . The lenticular lens array 40 a is composed of a plurality of concave elements 42 and convex elements 44 aligned orderly, wherein the concave element 42 is filled with light diffusing particles 46 . Close examination at the structure of concave element reveals a depression of concave shape 441 and a wavy contour of varying flatness. The drawback of aforementioned invention is that the lenticules array 40 a designed as such would require fabrication technologies involving semiconductor manufacturing and various sophisticated mechanical processing techniques, thus resulting in poor manufacturability and high manufacturing cost. Furthermore, despite having the advantage of being able to reduce the speckle patterns, as is claimed in this prior art, the aforementioned diffusion means is incapable of emitting light with superior brightness and good wide-angle uniformity. | <SOH> SUMMARY OF THE INVENTION <EOH>In light of the drawback associated with the prior art, the primary object of the present invention is to provide a high brightness diffuser consisted of at least two overlapping light diffusing pieces with ridge-shape structure arranged thereon, so that the high brightness diffuser with reduced thickness capable of emitting light of superior brightness and of wide-angle uniformity can be fabricated, and thus can be applied in a rear projection module. The secondary object of the present invention is to provide a solution for fabricating a high brightness diffuser comprising at least two light diffusing sheets, and each light diffusing sheet further comprising a substrate, a ridge-shaped layer and a diffusion layer, wherein the diffusion layer includes a transparent region and numerous light-diffusing particles uniformly dispersed inside the transparent region, and the substrate having a rugged external surface is sandwiched in between the ridge-shaped layer and the diffusion layer. Alternatively, the diffusion layer is placed in between the ridge-shaped layer and the substrate and the transparent region of the diffusion layer has a rugged surface facing toward the ridge-shaped layer. | 20040331 | 20060228 | 20050303 | 71466.0 | 0 | NGUYEN, THONG Q | HIGH BRIGHTNESS DIFFUSER | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,141 | ACCEPTED | TITANIUM HOCKEY STICK | A hockey stick shaft is a hollow, thin-walled tube formed of titanium or a titanium alloy. The tube wall has a thickness which may be uniform, tapered or stepped. The titanium or titanium alloy is of an alpha, a near-alpha, an alpha-beta or a highly-aged beta type. The titanium or titanium alloy has an elastic modulus greater than 13 million pounds per square inch (psi), a yield strength above 50,000 psi and a wall thickness ranging from 0.020 to 0.045 inches. An alternate hockey stick shaft has a titanium or titanium alloy core and exterior formed of a composite material. The titanium or titanium alloy core is of an alpha, a near-alpha, an alpha-beta or a beta type and has a yield strength above roughly 40,000 psi and a wall thickness ranging from 0.010 to 0.040 inches. | 1. A player hockey stick shaft comprising: an elongated one-piece wall forming a titanium or titanium alloy hollow tube having an upper end and a lower end adapted to receive a player hockey stick blade therein: wherein the titanium or titanium alloy has an elastic modulus greater than 13 million psi and a yield strength above 50,000 psi; and wherein the wall has a thickness in the range of 0.020 to 0.045 inches. 2-4. (canceled) 5. The shaft of claim 1 wherein the titanium or titanium alloy has a yield strength above 70,000 psi. 6. The shaft of claim 5 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 7. The shaft of claim 6 wherein the wall has a length in the range of 45 to 58 inches. 8. The shaft of claim 1 wherein the titanium or titanium alloy has an elastic modulus greater than 15 million psi. 9-10. (canceled) 11. The shaft of claim 8 wherein the titanium or titanium alloy has a yield strength above 70,000 psi. 12. The shaft of claim 11 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 13. The shaft of claim 1 wherein the wall has a length in the range of 45 to 58 inches. 14-16. (canceled) 17. The shaft of claim 1 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 18. The shaft of claim 17 wherein the tube is substantially rectangular in cross section and has a width and a thickness; and wherein the wall has a stiffness requiring a force ranging from 70 to 120 pounds applied across the thickness of the tube at a midpoint between the upper and lower ends of the wall to bend the wall to a one-inch deflection at the midpoint. 19. The shaft of claim 18 wherein the wall has a length ranging from 45 to 58 inches; and wherein the wall has a weight ranging from 250 to 450 grams. 20. The shaft of claim 1 wherein the titanium or titanium alloy is of an alpha, a near-alpha, an alpha-beta or a highly-aged beta type. 21. The shaft of claim 1 wherein the wall includes a hosel portion adapted to receive the blade and extending upwardly from the lower end; and wherein the wall has a first thickness adjacent the upper end and a second thickness above and adjacent the hosel portion which is less than the first thickness. 22. The shaft of claim 21 wherein the wall tapers inwardly and downwardly from adjacent the upper end to adjacent the lower end. 23. The shaft of claim 21 wherein the wall is stepped to define the first and second thicknesses. 24-29. (canceled) 30. The shaft of claim 1 wherein the titanium or titanium alloy has an elastic modulus greater than 14 million psi. 31. The shaft of claim 30 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 32. The shaft of claim 30 wherein the titanium or titanium alloy has a yield strength above 60,000 psi. 33. The shaft of claim 32 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 34. The shaft of claim 30 wherein the titanium or titanium alloy has a yield strength above 70,000 psi. 35. The shaft of claim 1 wherein the titanium or titanium alloy has a yield strength above 60,000 psi. 36. The shaft of claim 1 wherein the wall has a length ranging from 45 to 58 inches; and wherein the wall has a weight ranging from 250 to 450 grams. 37. The shaft of claim 6 wherein the titanium or titanium alloy has an elastic modulus greater than 14 million psi. 38. The shaft of claim 6 wherein the titanium or titanium alloy has an elastic modulus greater than 15 million psi. 39. The shaft of claim 8 wherein the titanium or titanium alloy has a yield strength above 60,000 psi. 40. The shaft of claim 39 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 41. The shaft of claim 8 wherein the wall has a thickness in the range of 0.025 to 0.035 inches. 42. The shaft of claim 17 wherein the titanium or titanium alloy has a yield strength above 60,000 psi. 43. The shaft of claim 1 wherein the hollow tube has an outer surface; and wherein the shaft is free of fiber-reinforced composite material bonded to the outer surface of the hollow tube. | BACKGROUND OF THE INVENTION 1. Technical Field The invention relates generally to hockey sticks. More particularly, the invention relates to a hockey stick having a light-weight shaft which is highly durable, impact-damage-resistant and dynamically responsive. Specifically, the invention relates to a thin-walled hockey stick shaft made of titanium or a titanium alloy. 2. Background Information Wood has been the traditional material of construction for ice and street hockey sticks. As such, the hard wood, Northern white-ash, is typically used in solid form for stick shafting (shafts) and blades. This hard wood has been attractive for hockey sticks based on high availability, flexibility, strength, hardness, ease of manufacturability into sticks, and, especially, low relative cost. Produced from a natural product, however, wood sticks inherently exhibit strong property directionality (i.e. texture), a relatively low elastic modulus, weak areas from defects and/or grain and composition inconsistencies, significant variability in durability and stiffness, and property and dimensional changes and/or warpage over time (instability). Furthermore, wood is highly susceptible to mechanical damage (cracking, splitting, chipping, denting) when impacted, especially when damage is imposed parallel to the grain direction. Wood sticks can become brittle at either temperature extreme, and/or over time as the natural moisture content of the wood diminishes (i.e., dries out). Flexure characteristics can change over time with use. Wood also possesses inherent energy dampening qualities, which act to reduce elastic energy transfer (snap) from the stick to the puck being shot. Some of these limitations with wood hockey sticks have been alleviated over the years through the application of fiberglass and/or carbon fiber reinforced plastic layers and laminates applied around the wood core. Not only does the fiberglass outer layer retard moisture egress from the wood core to extend stick shelf-life, it offers improved impact damage and cracking resistance to the wood. Furthermore, the glass and/or carbon fiber type and lay pattern can be used to enhance and control wood shaft and/or blade stiffness and dynamic response. Unfortunately, this fiberglass laminated and reinforced wood design results in fairly stiff and heavy hockey sticks (e.g., ˜660 grams for a one-piece stick). In the pursuit to improve hockey stick durability, consistency, and achieve lower net weight, extruded hollow aluminum alloy shafts (thin-wall seamless rectangular tubulars) were introduced around the mid to late 1980's. With this design, a replaceable laminated wood blade is inserted (with hot glue) into the hosel end of the aluminum shaft. Aluminum alloys, such as the 7005 alloy typically used in tennis rackets and baseball bats, offered tempered yield strengths on the order of 45,000-50,000 pounds per square inch (psi), in combination with good flexibility (elastic modulus ˜10.1 million psi) and a low density of 0.10 lb/in3. In order to achieve the shaft stiffness and damage/impact tolerance required, these aluminum shafts were typically designed with 0.045-0.060″ thick constant or tapered walls. As a result, modest shaft weight reductions on the order of 10-15% were achieved over wood. This metal shaft also featured performance consistency, long-term stability, and damage tolerance/life extension, compared to wood sticks. The integration of composite materials with aluminum to create “hybrid” shafts in the early 1990's provided further means to trim shaft weight, enhance shaft dynamic response/energy transfer, and adjust/control stiffness. Here again, glass- and/or carbon-reinforced plastic laminates and/or Kevlar (aramid) wraps were applied over aluminum tubular core reinforcements to control stiffness and create flex points along the shaft length. Despite these shaft material/design advances, commercial production of aluminum alloy hockey stick shafts has recently been discontinued. Fundamentally, this occurred due to the commercial availability of even lighter, more dynamically responsive, and often lower priced single-piece or two-piece all-composite sticks. Aluminum's inherent combination of lower strength and modulus properties limited the ability to design lighter weight sticks with the durability to withstand the rigors of hockey play. These aluminum shafts were known to suffer out-of-plane permanent set (yielding from bending), denting, and cracking in hosel corners. With their market entry in the mid-1990's, all-composite shafts and one-piece sticks today represent approximately two-thirds of the hockey stick market in North America. Despite prices which can range from 3-6 times that of wood stocks, the current market predominance of all-composite hockey sticks/shafts primarily stems from three basic performance features: 1. Lower weight: Composite shafts typically weigh 280-340 grams, or roughly 460-500 grams for a one-piece hockey stick. This represents a net weight reduction in the range of 25-37% over wood. Lighter weight translates into a faster and/or harder shot. 2. A wider range of stiffness: Typically, offense players prefer less-stiff (more flexible) shaft response for puck control and wrist-shots with quick snap. Stiffer sticks are generally favored by defensemen for slap-shots. Shaft stiffness is often commercially rated on the unofficial scale of 70-120 lb/in, related to the load to achieve a shaft mid-span deflection of one inch. 3. Improved, consistent energy transfer: Composite shafts/sticks exhibit enhanced elastic energy storage and transfer to the puck compared to wood shafts. This stems from reduced matrix dampening and the nature of glass- and/or carbon-fiber lay. Unlike wood, these flex and energy characteristics are highly controlled and consistent from stick to stick. Despite these attractive performance features, inadequate durability and impact damage tolerance of these fiber-reinforced plastic composites represent their greatest limitations. Composites are well known for their minimal resistance to impact damage which can produce undetectable, internal mechanical damage to the composite (e.g., fiber-matrix separation). This internal damage is very sensitive to the degree and direction of impact, and the shape-hardness of the impacting body. Although composite shafts may utilize Kevlar outer sheet wraps to mitigate impact damage to the composite substrate, brittle, cracking failure of composite shafts is still life limiting. This lack of durability is very serious since each all-composite shaft currently typically retails for $70-100, and the one-piece composite stick is typically priced in the range of $170-200. This poor stick life cycle cost scenario has recently financially impacted professional hockey teams, where replacement composite stick budgets have skyrocketed. Less critical durability issues with composites include effects at extreme temperature limits. Repeated overheating of the shaft hosel area incurred during blade replacement procedure using hot glue can produce composite blistering and weakening, whereas very cold outdoor winter temperatures can make sticks more prone to brittle fracture. U.S. Pat. No. 5,863,268 granted to Birch discloses a metal goalkeeper's hockey stick, which has a blade and shaft which are preferably formed of an aluminum alloy, but which may also be formed of a titanium alloy. However, the Birch hockey stick is specifically one used by a goalie or goaltender, which is completely different than that of a “player” hockey stick, that is, one used by the players (forward and defense men) other than the goalie. Goalie sticks and player sticks are not interchangeable with one another and indeed each would be completely inadequate if used in the stead of the other. The goalie hockey stick is configured for a completely different purpose than the player hockey stick. The goalie stick is configured primarily for blocking shots or deflecting shots away and thus utilizes a substantially enlarged blade for that purpose, along with a substantially shortened shaft. By contrast, the player sticks are alternately used for maneuvering and/or passing the puck quickly while sometimes skating at high speeds; making wrist-shots with quick snap; and making slap-shots which launch the puck at high speed. Thus, sticks with various stiffness and flex characteristics are important in player sticks. Typically, forward or offensive players prefer less-stiff (more flexible) shaft response for puck control and wrist-shots with quick snap. Stiffer sticks are generally favored by defense men for slap-shots. In keeping with the difference in purposes of the sticks, the blade of the goalie stick, as shown by Birch, has a horizontal portion and an upstanding portion which is substantially longer than (nearly twice as long as) the horizontal portion. In addition, the upstanding portion of the blade is roughly the same width as the horizontal portion. By contrast, the blade of the player stick has a relatively short upwardly extending portion, mainly for the purpose of providing a transition for connecting to the shaft. This upwardly extending portion is also substantially narrower than the horizontal portion of the player blade. While the Birch shaft is a hollow tube, it is substantially shorter at approximately 32 inches than the shaft of the typical player hockey stick, which is roughly 50 inches, although this varies. Due in part to the relatively long upstanding portion of the goalie blade, a longer shaft is not suitable for use with the goalie stick. The substantially longer shaft of the player stick alone creates a completely different dynamic aspect from that of a goalie stick shaft. As a result of the distinct purpose and the correspondingly different size, the player stick shaft must incorporate various parameters quite distinct from those of the goalie stick shaft. BRIEF SUMMARY OF THE INVENTION The present invention provides a player hockey stick shaft comprising an elongated one-piece wall forming a titanium or titanium alloy hollow tube having an upper end and a lower end adapted to receive a player hockey stick blade therein. One embodiment features the wall forming the tube with a thickness ranging from 0.020 to 0.045 inches; and the titanium or titanium alloy having an elastic modulus above 13 million pounds per square inch and a yield strength above 50,000 pounds per square inch. The present invention also provides a player hockey stick shaft comprising an elongated titanium or titanium alloy core having an outer surface, an upper end and a lower end adapted to connect to a player hockey stick blade; and a composite material connected to the outer surface of the core. One embodiment features the core having a wall with a thickness ranging from 0.010 to 0.040 inches and the titanium or titanium alloy having a yield strength above 40,000 pounds per square inch. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS Preferred embodiments of the invention, illustrative of the best modes in which applicant contemplates applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. FIG. 1 is a side elevational view of a first embodiment of the present invention. FIG. 2 is a view similar to FIG. 1 with portions cut away to show a sectional view of the shaft of the first embodiment. FIG. 3 is an enlarged sectional view taken on line 3-3 of FIG. 1. FIG. 4 is a view similar to FIG. 2 of a second embodiment of the present invention. FIG. 5 is an enlarged sectional view taken on line 5-5 of FIG. 4. FIG. 6 is an enlarged sectional view taken on line 6-6 of FIG. 4. FIG. 7 is a view similar to FIG. 2 of a third embodiment of the present invention. FIG. 8 is a side elevational view of a fourth embodiment of the present invention. FIG. 9 is an enlarged sectional view of the encircled portion of FIG. 8. FIG. 10 is an enlarged sectional view taken on line 10-10 of FIG. 8. FIG. 11 is an enlarged sectional view of a fifth embodiment of the present invention. Similar numerals refer to similar parts throughout the specification. DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the hockey stick shaft of the present invention is indicated generally at 100 in FIGS. 1-3; a second embodiment indicated generally at 200 in FIGS. 4-6; a third embodiment indicated generally at 300 in FIG. 7; a fourth embodiment indicated generally at 400 in FIGS. 8-10; and a fifth embodiment indicated generally at 500 in FIG. 11. Shafts 100, 200, 300, 400 and 500 are configured for use with a “player” hockey stick, which for the purposes of this application excludes a goalie or goaltender hockey stick, which, as discussed in the Background section above, serves a different purpose and consequently has a much different configuration and substantially different dynamics. Shaft 100 is shown in FIGS. 1-2 as part of a player hockey stick 102 which further includes a knob 104 with an insertion shaft 105 and a replaceable player hockey stick blade 106 having an insertion shaft 108 with an upper end 109. Shaft 100 is an elongated one-piece hollow tube formed of unalloyed titanium or a titanium alloy. The tube is substantially rectangular and has a width 101 and a thickness 103 (FIG. 3). Although the dimensions of width 101 and thickness 103 may vary, for typical regulation player hockey sticks, width 101 does not exceed 3 centimeters (1.18 inches) and thickness 103 does not exceed 2.5 centimeters (0.984 inch), in accordance with the Rules of USA Hockey and of the National Hockey League, the sanctioning bodies for most hockey play in the United States. Other league rules may limit these dimensions differently or may not specify such limitations. Shaft 100 has an upper end 110 which receives insertion shaft 105 of knob 104 and a lower end 112 which defines a hosel portion 114 which receives insertion shaft 108 of blade 106. Blade 106 is most commonly connected to shaft 100 with hot glue although other attaching means known in the art may be used. Shaft 100 has a flex point 115 just above hosel portion 114, that is, just above upper end 109 of insertion shaft 108. Shaft has a midpoint 117 between ends 110 and 112 and a length 119 extending the full distance between ends 110 and 112. Length 119 typically ranges from 36 to 58 inches, more preferably from 45 to 58 inches and even more preferably, from 45 to 55 inches. Length 119 differs to suit the size of the player and for purposes of most league play, is limited by rules indicating that hockey sticks will not exceed 63 inches from the heel to the upper end of the shaft (according to rules of USA Hockey and the National Hockey League). Thus, length 119, to comply with such rules, would be limited so that shaft 100 in combination with the pertinent part of the blade would fall within the length from the heel to the end of the shaft. Shaft 100 has an elongated wall 116 which is formed integrally of one piece and defines an elongated interior chamber 118. Wall 116 has a rectangular cross section and a thickness 120 (FIG. 3) which is substantially uniform over the entire length 119 of shaft 100. Wall 116 has an outer perimeter which is substantially uniform from upper end 110 to lower end 112. More particularly, the titanium or titanium alloy of shaft 100 is of an alpha, a near-alpha, an alpha-beta or a highly-aged beta type. The titanium or titanium alloy has an elastic modulus which is greater than 13 million pounds per square inch (psi), preferably greater than 14 million psi and more preferably greater than 15 million psi. The relatively high elastic modulus provides suitable stiffness to the shaft. The titanium alloy has a yield strength above roughly 50,000 psi, preferably above 60,000 psi and more preferably above 70,000 psi. This range of yield strength is required to adequately resist impact damage and avoid shaft bowing or permanent distortion. The thickness 120 of wall 116 is in the range of 0.020 to 0.045 inches and preferably in the range of 0.025 to 0.035 inches. These wall thickness ranges allow for a favorable combination of shaft stiffness, damage resistance and weight. More detailed information about the unalloyed and alloyed titanium used and the characteristics thereof with regard to hockey stick shafts is provided following the description of all the embodiments of the shaft of the present invention. Shaft 200 (FIGS. 4-6) is similar to shaft 100 except it has a variable-thickness wall. Shaft 200 is formed of the titanium or titanium alloys noted with regard to shaft 100 with the same range of elastic modulus, yield strength and wall thickness. Adjacent lower end 112, shaft 200 defines a hosel portion 214 which receives insertion shaft 108 of blade 106. Shaft 200 has an elongated wall 216 which is formed integrally of one piece and defines an elongated interior chamber 218 which tapers at a uniform rate outwardly and downwardly from upper end 110 toward lower end 112. Wall 216 has an outer perimeter which is substantially uniform from upper end 110 to lower end 112. Wall 216 has a rectangular cross section and tapers downwardly and inwardly from upper end 110 toward lower end 112. Thus, wall 216 is thicker adjacent upper end 110, as represented by a first thickness 220 (FIG. 5), than adjacent lower end 112, as represented by a second thickness 222 (FIG. 6). More particularly, second thickness 222 is spaced upwardly from hosel portion 214. This thinner section of wall 216 adjacent and above hosel portion 214 provides increased flex for “kick-off” while the thicker sections of wall 216 closer to upper end 110 provide a stiffer upper shaft portion, thus providing improved snap (high energy transfer to the puck) and control of the hockey puck in passing and shooting. A modified wall may be tapered inwardly on its outer surface instead of its inner surface to achieve similar thicker and thinner wall portions. Shaft 300 is similar to shaft 100 except for the configuration of wall 316. Shaft 300 is formed of the titanium or titanium alloys noted with regard to shaft 100 with the same range of elastic modulus, yield strength and wall thickness. Adjacent lower end 112, shaft 300 defines a hosel portion 314 which receives insertion shaft 108 of blade 106. Wall 316 has an upper portion 317 having a substantially uniform thickness which is greater than the thickness of a lower portion 319 which also has a substantially uniform thickness. The thickness of upper portion 317 and the thickness of lower portion 319 each fall within the wall thickness range noted above, that is, as detailed with regard to shaft 100. Wall 316 has an inner surface 315 defining an interior chamber 318 which is divided into an upper chamber 318A defined by upper portion 317 and a lower chamber 318B defined by lower portion 319. Upper portion 317 steps outwardly along inner surface 315 into lower portion 319 at step 321. Similar to second thickness 222 of shaft 200, lower portion 319 has a decreased thickness which extends upwardly from hosel portion 314 and which is thus above and adjacent hosel portion 314. Similar to shaft 200, this thinner section of wall 316 adjacent and above hosel portion 314 provides increased flex while thicker upper portion 317 provides a stiffer upper shaft portion, thus providing the improved snap and control noted above. A modified wall may be stepped inwardly on its outer surface instead of its inner surface to achieve similar thicker and thinner wall portions. With regard to shafts 100-300, as illustrated in part by shafts 200 and 300, the shaft walls may be selectively thinned in areas to create flex points. These flex points may occur at various locations along the shaft in addition to the noted flex points adjacent and above respective hosel portions 214 and 314 of shafts 200 and 300. On the other hand, it may be desired to have a thicker wall in certain areas of the shaft, for instance, in the hosel portion in order to provide additional strength against cracking in this high-stress area. As is known in the art, stiffness and flexibility may also be controlled by fillers at desired places within the hollow shafts. Shaft 400 (FIGS. 8-10) is similar to shaft 100 except that shaft 400 combines a titanium or titanium alloy shaft with composite materials to provide additional advantages. In addition, the range of dimensions and specific unalloyed titanium or titanium alloys which may be used with shaft 400 vary somewhat from those used with shaft 100, as further detailed below. Shaft 400 includes an elongated one-piece hollow tube formed of unalloyed titanium or a titanium alloy, although it may be formed in sections joined together by, for example, welding, brazing, adhesive bonding and/or mechanical fasteners. Shaft 400 has an elongated wall 416 which has an outer surface 417 and is formed integrally of one piece and defines an elongated interior chamber 418. Wall 416 has a rectangular cross section and a thickness 420 (FIG. 10) which is substantially uniform over the entire length of shaft 400, although this may vary, as with the previous embodiments, for example. Shaft 400 also includes composite material 424, shown as a plurality of layers 426, which encases wall 416 and is bonded to outer surface 417 of wall 416. The tube of shaft 400 serves as an internal support or core of shaft 400 and as a non-removable mandrel for the application of uncured fiber-reinforced composite materials via traditional sheet-rolling, sheet-wrapping or filament winding methods. (See, for example, U.S. Pat. No. 6,354,960). Composite material 424 is bonded to outer surface 417 during thermal curing of composite material 424. This hybrid composite-titanium hockey shaft provides improved durability and impact-damage-resistance compared to all-composite shafts while providing stiffness control and maintaining light-weight and highly dynamically-responsive shaft properties. The titanium or titanium alloy forming the core of shaft 400 is of an alpha, a near-alpha, an alpha-beta or a beta type. In comparison to shafts 100, 200 and 300, the elastic modulus of the titanium or titanium alloy of shaft 400 is not as critical because the composite material is configured to provide suitable stiffness to shaft 400. Thus, a titanium or titanium alloy having an elastic modulus substantially lower than the ranges noted with regard to the previous embodiments may be used, although said ranges are very well suited to shaft 400 as well. The titanium alloy has a yield strength above roughly 40,000 psi, although the higher strengths noted above are preferred. The thickness of wall 420 is in the range of 0.010 to 0.040 inches and may uniform or variable. The combination of a titanium-based core with a composite external material retains the positive characteristics of the composite material while adding the titanium-related characteristics, particularly the ability to better withstand impact damage which so often renders all-composite shafts nonfunctional. In addition, the use of the titanium or titanium core as a non-removable mandrel greatly simplifies the formation of the titanium-composite shaft in comparison to the formation of an all-composite shaft, which requires the more difficult, added task of removing a mandrel. Shaft 500 (FIG. 11) is similar to shaft 400 except that shaft 500 includes an intermediate structure 520 between a cylindrical core and composite material. The core of shaft 500 is formed of the titanium or titanium alloys noted with regard to shaft 400 with the same range of yield strength and wall thickness. The elastic modulus characteristics of shaft 500 are also the same as noted with regard to shaft 400. The core of shaft 500 has an elongated wall 516 which has an outer surface 517 and defines an elongated interior chamber 518. Intermediate structure 520 is bonded to outer surface 517 and has an outer surface 522. Shaft 500 includes composite material 524, shown as a plurality of layers 526, which is bonded to outer surface 522 of structure 520, thereby encasing intermediate structure 520 and wall 516 with intermediate structure 520 disposed between wall 516 and composite material 520. Intermediate structure 520 may be formed of a wide variety of materials, for example, a polymeric material which may be foamed or solid, an elastomer, or wood. Most preferably, such a material is light weight in order to maintain a light weight shaft while taking advantage of characteristics of the titanium core and composite outer layer. Structure 520 provides the additional benefits of a third material between wall 516 and composite material 524 and permits the use of cores with various shapes to be built up to provide a rectangular cross-section suited to produce a rectangular shaft while retaining the advantages of the composite-titanium combination. With regard to shafts 400 and 500, the cross sectional shape of the tube may be any other suitable shape, for example, oval, square or triangular. Further, with regard to composite-titanium shafts such as shafts 400 and 500, where the titanium or alloy thereof serves as an internal reinforcement structure, the tube may be flattened, corrugated, tapered, stepped, slotted and so forth. Alternately, the tube may be replaced with a non-tubular internal structure which is flat, corrugated, tapered, stepped, slotted and so forth. These varying configurations of the core allow modification of the rigidity of given sections and/or the net weight of the tube. With regard to shafts 400 and 500 and similar composite-titanium hybrid shafts, the composite material may be applied along the shaft tube or other internal structure in various thicknesses and with fibers extending in different directions in order to control and optimize the dynamic response of the hockey stick shaft and/or blade. Stiffness and flex points may be controlled in this manner. In addition, the internal titanium structure may be selectively thinned in areas to create flex points. Table 1 below compares some of the pertinent properties of various commercial grade unalloyed titanium and titanium alloys. TABLE 1 Property Comparison of Various Types of Commercial Titanium Alloys Elastic Titanium Alloy Modulus Density Alloy Type (ASTM Grade) Min. YS (103 psi) (106 psi) (g/cm3) Alpha Unalloyed Ti (Gr. 1) 25 15.1 4.51 Unalloyed Ti (Gr. 2) 40 15.1 4.51 Unalloyed Ti (Gr. 3) 55 15.2 4.51 Unalloyed Ti (Gr. 4) 70 15.3 4.51 Ti—0.3Mo—0.8Ni (Gr. 12) 50 15.1 4.51 Ti—5Al—2.5Sn (Gr. 6) 115 17 4.48 Near-alpha Ti—3Al—2.5V (Gr. 9) 70 15.5 4.48 Ti—6Al—2Sn—4Zr—2Mo—0.1Si 120 16.5 4.54 Alpha-beta Ti—6Al—4V ELI (Gr. 23) 110 16.5 4.43 Ti—6Al—4V (Gr. 5) 120 16.5 4.43 Ti—4.5Al—3V—2Mo—2Fe 120 15.9 4.54 Ti—6Al—2Sn—2Zr—2Mo—2Cr—0.15Si 160 17.0 4.65 Beta Ti—15V—3Al—3Cr—3Sn 110-160 12-15 4.76 Ti—3Al—8V—6Cr—4Zr—4Mo 115-160* 13-15 4.82 Ti—15Mo—2.5Nb—3Al—0.2Si 115-160* 13-15 4.94 *Can be aged to various minimum yield strength values. To help determine the thickness of the wall 120, shaft flexure (stiffness) behavior of titanium and aluminum as a hollow rectangular tube was modeled. This model was based on a typical hockey stick shaft bend loading scenario using a 50-inch shaft. In this model, the shaft is loaded in bending (as when shooting the puck) by a player's lower hand across the smaller dimension (as at thickness 103 of shaft 100) of the rectangular cross section approximately at the midpoint, as at midpoint 117 of shaft 100. Because a two- to three-inch wooden knob is typically inserted in the upper end of the shaft, the unsupported span for shaft flexing in this model is approximately 47.0 to 47.5 inches. While there are no formal standards for ice hockey sticks, the stiffness is often defined in the industry as the force (in pounds) to bend a shaft to a one-inch deflection at the load point (i.e., the midpoint). The typical stiffness for wood, aluminum and composite shafts range from approximately 70 to 120 pounds per inch of deflection, with approximately 100 pounds per inch of deflection being most popular. Results of this model are shown in Table 2 below, and include a comparison of titanium, aluminum, composite and wood shafts. TABLE 2 Comparison of Hockey Stick Shaft Materials 70 lb/in 85 lb/in 100 lb/in Shaft stiffness stiffness stiffness Shaft Dimensions Wall Wall Wall Material (in) (in) Wt (g) (in) Wt (g) (in) Wt (g) N. White-ash 1.15 × 0.80 × 47.5 — — — — Solid 459* (wood) Aluminum 1.05 × 0.72 × 47.5 0.034 244 0.042 299 0.051 359 1.15 × 0.76 × 47.5 0.031 242 0.038 294 0.047 360 Composite 1.16 × 0.76 × 47.5 0.078-0.093 290-340 0.078-0.093 290-325 0.078-0.093 290-340 Titanium - 1.05 × 0.72 × 47.5 0.021 255 0.026 314 0.032 383 unalloyed 1.05 × 0.76 × 47.5 0.019 236 0.023 285 0.028 345 1.05 × 0.80 × 47.5 0.016 204 0.020 254 0.025 316 1.15 × 0.72 × 47.5 0.020 257 0.024 307 0.029 369 1.15 × 0.76 × 47.5 0.017 224 0.021 275 0.025 326 1.15 × 0.80 × 47.5 0.015 202 0.019 255 0.022 294 Ti—3Al—2.5V 1.05 × 0.72 × 47.5 0.020 241 0.025 300 0.030 358 (near-alpha Ti alloy) Ti—6Al—4V 1.05 × 0.72 × 47.5 0.020 239 0.024 285 0.029 342 (alpha-beta Ti alloy) Ti-15-3-3-3 1.05 × 0.72 × 47.5 0.024 306 0.030 380 0.036 453 (beta Ti alloy) *For a 47.5″ shaft length only. This model was used to determine the wall thickness needed to achieve certain shaft stiffness values. The model results revealed that it is possible to achieve equivalent stiffness with substantially thinner walls and often lower net shaft weights than aluminum and composites. The higher-density/lower-modulus beta titanium alloys are an exception, being significantly heavier than aluminum and composite shafts. Surprisingly, because of the desire to keep the weight of the shaft within such a low range, some of the walls became so thin that it was necessary to increase the elastic modulus in order to maintain sufficient shaft stiffness, whereas normally it would be expected that a metal shaft would be stiff enough to require a lower elastic modulus. Thus, titanium alloys with sufficiently high elastic modulus were needed in such cases. It is noted that the shaft weight results determined from the model were only determined with regard to stiffness and do not consider wall thicknesses needed to adequately resist mechanical damage or hosel end overload/cracking. Hockey stick shafts are subject to impact by pucks or hockey sticks of opponents. Thus, resistance to denting and permanent set (yielding) is a pertinent issue. Experience with aluminum alloy shafts shows susceptibility to some denting. Further, repeated use of aluminum alloy sticks, particularly as a result of slap shots, can slowly bow or deform the shafts, implying that the aluminum alloy yield strength was exceeded. Table 3 below shows a dent resistance comparison of aluminum alloy and unalloyed titanium hollow shafts. Based on elastic strain energy theory, the intrinsic resistance to permanent impact damage of a thin-wall surface is proportional to the square of the yield strength (YS) multiplied by the wall thickness (t) divided by the elastic modulus (E). Table 3 compares an aluminum alloy (e.g., 2004 or 7005) with typical wall thicknesses of 0.045 and 0.050 inches with titanium walls having respective thicknesses of 0.025, 0.030 and 0.033 inches. TABLE 3 Dent Resistance Comparison: Al Alloy vs. Unalloyed Ti Hollow Shafts YS E Wall (t) Relative Dent Alloy (103 psi) (106 psi) (in.) Resistance Al 2024 or 7005 50 10.5 0.045 10.7 0.050 11.9 Gr. 2 Ti 50 15.1 0.025 4.1 0.030 5.0 0.033 5.5 Gr. 3 Ti 62 15.3 0.025 6.3 0.030 7.5 0.033 8.3 Gr. 4 Ti 75 15.5 0.025 9.1 0.030 10.9 0.033 12.0 80 15.5 0.025 103 0.030 12.4 0.033 13.6 85 15.5 0.025 11.7 0.030 14.0 0.033 15.4 Denting resistance ( yielding on impact ) ∝ ( YS ) 2 E × t where t = wall thickness YS = nominal yield strength E = elastic modulus Table 3 reveals that the softer, lower strength unalloyed titanium Grades 2 and 3 are not expected to resist yielding or denting as well as the conventional aluminum alloy hockey shafts while maintaining the thin walls needed to achieve a desirable weight for the shaft. Impact damage resistance which is comparable to the aluminum shafts occurs with a yield strength in the order of 75,000 psi. To provide improved durability over traditional aluminum alloy shafts, the Grade 4 alloy must be increased to approximately 80,000 psi or above. These findings indicate that the much higher strength alpha-beta titanium alloys and the lower modulus beta titanium alloys will also provide sufficient and improved dent resistance. In furtherance of determining the various pertinent characteristics of titanium-based shafts, unalloyed titanium shafts of Grade 2 and Grade 4 titanium were subjected to field tests during hockey practice and game play, the results of which are found in Table 4 below. These tests included shafts having wall thicknesses which were uniform, tapered or stepped, as described above with regard to shafts 100, 200 and 300. However, some of the stepped shafts used in the tests involved two steps and subsequently three sections each having a different thickness. The wall thickness of each section of the stepped shafts used in the tests is uniform. As noted in Table 4, the length of the shafts tested ranged from 47.5 to 50.0 inches. The width and thickness of the shafts tested also varied slightly. As also noted in Table 4, some of the shafts were annealed and others were not. TABLE 4 Field Performance of Prototype Titanium Hockey Stick Shafts Wall Shaft Shaft No. Ti Alloy Shaft Width × Thickness Thickness Length Weight Times Performance (condition) (in.) (in.) ‡ (in.) (g) Used** Ratings Gr. 2 Ti 1.02 × 0.73 0.031 47.6 349 2 C (annealed) Gr. 2 Ti 1.02 × 0.73 0.031 47.9 351 3 A (annealed) Gr. 4 Ti 1.03 × 0.76 0.025 48.1 286 2 D (not annealed) Gr. 4 Ti 1.03 × 0.75 0.025 48.0 286 1 A (not annealed) Gr. 4 Ti 1.06 × 0.76 0.033 47.5 368 2 A (annealed) Gr. 4 Ti 1.06 × 0.76 0.033 50.0 388 23 A, B (annealed) Gr. 4 Ti* 1.05 × 0.76 0.033 (30″) 50.0 369 6 A (annealed) 0.026 (17″) Gr. 4 Ti* 1.05 × 0.76 0.033 (27.5″) 47.5 354 7 A (annealed) 0.026 (17″) Gr. 4 Ti* 1.05 × 0.76 0.033 (25.5″) 47.5 352 16 A (annealed) 0.027 (19″) Gr. 4 Ti* 1.05 × 0.76 0.033 (27.5″) 47.5 347 6 A, B (not annealed) 0.028 (17″) Gr. 4 Ti* 1.05 × 0.76 0.033 (27.5″) 47.5 359 9 A, B (not annealed) 0.030 (17″) Gr. 4 Ti* 1.05 × 0.76 0.033 (30″) 50.0 375 12 A, B (annealed) 0.031 (12″) 0.028 (5″) Gr. 4 Ti* 1.05 × 0.76 0.033 (30″) 50.0 377 6 A, B (annealed) 0.031 (12″) 0.028 (5″) Legend: A - No cracking or bowing, remained intact and fully functional B - Exhibited shallow denting, but remained fully functional C - Experienced noticeable bowing (permanent distortion) D - Experienced buckling/collapse/kinking and complete failure *Indicates a shaft incorporating multi-step wall thicknesses **Each time typically consisted of an hour of either team practice or an actual game at the high school or adult league level ‡ Numbers in parentheses indicate the length of the shaft section having the indicated wall thickness; the first parenthetical number corresponding to a first section extending downwardly from the upper end of the shaft, the second parenthetical number corresponding to a second section adjacent and below the first section, and the third parenthetical number, if any, corresponding to a third section adjacent and below the # second section; the hosel portion, not indicated, is adjacent and below the second section (or third section, if any) and is 3 inches long The field tests indicated that Grade 2 titanium shafts may experience noticeable bowing and permanent distortion or yielding from hard slap shots and/or severe stick clashing, even at wall thicknesses as high as 0.031 inches. Further, titanium shafts with thinner walls (0.025 inches and below) can experience rapid kinking (unstable shaft buckling/collapse) and breakage from hard slap shots and/or severe stick clashes. Grade 4 titanium shafts with walls above 0.025 inches (stepped or uniform thickness) remained fully functional and intact, and resisted cracking, kinking, failure and bowing (permanent deformation). Shallow denting did not appear to influence shaft life or performance. In fact, shafts incurring fairly substantial denting during use subsequent to the above-noted field tests have remained fully functional. The survivability of these shafts under the rigors of actual playing conditions was unexpected given such thin walls. Shaft tube weld seams and hosel end areas remained undeformed, uncracked and fully intact. The standard hot glue for attaching the blade to the shaft worked well with the titanium shafts and was unaffected by hosel zone heating cycles. Based on these tests, it was found that the shafts which were viable under actual playing conditions and also had a desirable weight fell within a rough weight range of 280 to 400 grams. Based on these results, viable shafts having a length in the range of 45 to 58 inches would be expected to have respective weights in the range of roughly 250 to 450 grams. Weight ranges for viable shafts of other lengths may be similarly calculated. Viable shafts may be possible below these weight ranges by reducing the shaft width and/or thickness, although these dimensions must be sufficiently large to ensure a proper grip on the shaft, absent building the shaft up with other materials. The field tests also produced feedback from players using the tested sticks. This feedback indicated that the sticks were lightweight, very flexible and had a rugged durable feel. Unlike aluminum shafts, there were no vibration or harmonic issues related to the titanium shafts. This was an unexpectedly good result, because metals, due to their low dampening capacity, are normally expected to create undesirable vibrations and harmonic issues, but the titanium shafts were free of this type of problem. The sticks were reportedly very responsive and had excellent snap in wrist-shots (high energy transfer to the puck). Good accuracy/puck control was also reported in wrist-shots. The control and feel during puck handling was good and passing accuracy was improved. The tapered and multi-step wall shafts provided improved snap/dynamic response compared to the shafts of uniform wall thickness. Table 5 below summarizes the comparative characteristics of hockey stick shafts made of various materials. As easily discerned from Table 5, the titanium or titanium alloy shafts have desirable characteristics across the board, other than the low to medium cost of manufacturing, which is really more of a neutral feature and in contrast with the typical expectation of high cost for titanium products in general. Even if the cost to manufacture were high, it would be offset by the low life cycle cost due to the longer projected service life. The ability to provide all these desirable characteristics with a titanium shaft in contrast to the other materials is a substantial breakthrough in the advancement of hockey sticks. TABLE 5 Comparison of Hockey Stick Shaft Materials Shaft Material Property/Aspect Wood Aluminum Composite Titanium Weight high high low low Performance Consistency low high high high Damage Resistance low medium low high (durability) Projected Service Life low medium low high Long-term Stability low high medium high (shelf life/temperature resistance) Energy Transfer (snap) low medium high high Cost to Manufacture low low-med med-high low-med Life Cycle Cost med-high low high low Note: Underlined indicates a negative or undesirable feature. Bold-face type indicates a positive or desirable feature. In summary, shafts 100, 200, 300, 400 and 500 are lighter than conventional wood or aluminum hockey stick shafts of equivalent length and approach or are similar to the weight of all-composite shafts. Despite the thin walls of these titanium shafts, they are more dynamically responsive and provide improved energy transfer from the stick to the puck than conventional wood and aluminum shafts. Also in spite of the thin walls of the titanium shafts, they are substantially more physically durable and impact-damage-resistant than wood and composite shafts. They are also more heat-resistant than wood and composite shafts. Thus, the service life of these improved shafts is substantially lengthened. Because blades and knobs are replaced using hot glue procedures, it is important that these shafts do not suffer heat damage. In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Technical Field The invention relates generally to hockey sticks. More particularly, the invention relates to a hockey stick having a light-weight shaft which is highly durable, impact-damage-resistant and dynamically responsive. Specifically, the invention relates to a thin-walled hockey stick shaft made of titanium or a titanium alloy. 2. Background Information Wood has been the traditional material of construction for ice and street hockey sticks. As such, the hard wood, Northern white-ash, is typically used in solid form for stick shafting (shafts) and blades. This hard wood has been attractive for hockey sticks based on high availability, flexibility, strength, hardness, ease of manufacturability into sticks, and, especially, low relative cost. Produced from a natural product, however, wood sticks inherently exhibit strong property directionality (i.e. texture), a relatively low elastic modulus, weak areas from defects and/or grain and composition inconsistencies, significant variability in durability and stiffness, and property and dimensional changes and/or warpage over time (instability). Furthermore, wood is highly susceptible to mechanical damage (cracking, splitting, chipping, denting) when impacted, especially when damage is imposed parallel to the grain direction. Wood sticks can become brittle at either temperature extreme, and/or over time as the natural moisture content of the wood diminishes (i.e., dries out). Flexure characteristics can change over time with use. Wood also possesses inherent energy dampening qualities, which act to reduce elastic energy transfer (snap) from the stick to the puck being shot. Some of these limitations with wood hockey sticks have been alleviated over the years through the application of fiberglass and/or carbon fiber reinforced plastic layers and laminates applied around the wood core. Not only does the fiberglass outer layer retard moisture egress from the wood core to extend stick shelf-life, it offers improved impact damage and cracking resistance to the wood. Furthermore, the glass and/or carbon fiber type and lay pattern can be used to enhance and control wood shaft and/or blade stiffness and dynamic response. Unfortunately, this fiberglass laminated and reinforced wood design results in fairly stiff and heavy hockey sticks (e.g., ˜660 grams for a one-piece stick). In the pursuit to improve hockey stick durability, consistency, and achieve lower net weight, extruded hollow aluminum alloy shafts (thin-wall seamless rectangular tubulars) were introduced around the mid to late 1980's. With this design, a replaceable laminated wood blade is inserted (with hot glue) into the hosel end of the aluminum shaft. Aluminum alloys, such as the 7005 alloy typically used in tennis rackets and baseball bats, offered tempered yield strengths on the order of 45,000-50,000 pounds per square inch (psi), in combination with good flexibility (elastic modulus ˜10.1 million psi) and a low density of 0.10 lb/in 3 . In order to achieve the shaft stiffness and damage/impact tolerance required, these aluminum shafts were typically designed with 0.045-0.060″ thick constant or tapered walls. As a result, modest shaft weight reductions on the order of 10-15% were achieved over wood. This metal shaft also featured performance consistency, long-term stability, and damage tolerance/life extension, compared to wood sticks. The integration of composite materials with aluminum to create “hybrid” shafts in the early 1990's provided further means to trim shaft weight, enhance shaft dynamic response/energy transfer, and adjust/control stiffness. Here again, glass- and/or carbon-reinforced plastic laminates and/or Kevlar (aramid) wraps were applied over aluminum tubular core reinforcements to control stiffness and create flex points along the shaft length. Despite these shaft material/design advances, commercial production of aluminum alloy hockey stick shafts has recently been discontinued. Fundamentally, this occurred due to the commercial availability of even lighter, more dynamically responsive, and often lower priced single-piece or two-piece all-composite sticks. Aluminum's inherent combination of lower strength and modulus properties limited the ability to design lighter weight sticks with the durability to withstand the rigors of hockey play. These aluminum shafts were known to suffer out-of-plane permanent set (yielding from bending), denting, and cracking in hosel corners. With their market entry in the mid-1990's, all-composite shafts and one-piece sticks today represent approximately two-thirds of the hockey stick market in North America. Despite prices which can range from 3-6 times that of wood stocks, the current market predominance of all-composite hockey sticks/shafts primarily stems from three basic performance features: 1. Lower weight: Composite shafts typically weigh 280-340 grams, or roughly 460-500 grams for a one-piece hockey stick. This represents a net weight reduction in the range of 25-37% over wood. Lighter weight translates into a faster and/or harder shot. 2. A wider range of stiffness: Typically, offense players prefer less-stiff (more flexible) shaft response for puck control and wrist-shots with quick snap. Stiffer sticks are generally favored by defensemen for slap-shots. Shaft stiffness is often commercially rated on the unofficial scale of 70-120 lb/in, related to the load to achieve a shaft mid-span deflection of one inch. 3. Improved, consistent energy transfer: Composite shafts/sticks exhibit enhanced elastic energy storage and transfer to the puck compared to wood shafts. This stems from reduced matrix dampening and the nature of glass- and/or carbon-fiber lay. Unlike wood, these flex and energy characteristics are highly controlled and consistent from stick to stick. Despite these attractive performance features, inadequate durability and impact damage tolerance of these fiber-reinforced plastic composites represent their greatest limitations. Composites are well known for their minimal resistance to impact damage which can produce undetectable, internal mechanical damage to the composite (e.g., fiber-matrix separation). This internal damage is very sensitive to the degree and direction of impact, and the shape-hardness of the impacting body. Although composite shafts may utilize Kevlar outer sheet wraps to mitigate impact damage to the composite substrate, brittle, cracking failure of composite shafts is still life limiting. This lack of durability is very serious since each all-composite shaft currently typically retails for $70-100, and the one-piece composite stick is typically priced in the range of $170-200. This poor stick life cycle cost scenario has recently financially impacted professional hockey teams, where replacement composite stick budgets have skyrocketed. Less critical durability issues with composites include effects at extreme temperature limits. Repeated overheating of the shaft hosel area incurred during blade replacement procedure using hot glue can produce composite blistering and weakening, whereas very cold outdoor winter temperatures can make sticks more prone to brittle fracture. U.S. Pat. No. 5,863,268 granted to Birch discloses a metal goalkeeper's hockey stick, which has a blade and shaft which are preferably formed of an aluminum alloy, but which may also be formed of a titanium alloy. However, the Birch hockey stick is specifically one used by a goalie or goaltender, which is completely different than that of a “player” hockey stick, that is, one used by the players (forward and defense men) other than the goalie. Goalie sticks and player sticks are not interchangeable with one another and indeed each would be completely inadequate if used in the stead of the other. The goalie hockey stick is configured for a completely different purpose than the player hockey stick. The goalie stick is configured primarily for blocking shots or deflecting shots away and thus utilizes a substantially enlarged blade for that purpose, along with a substantially shortened shaft. By contrast, the player sticks are alternately used for maneuvering and/or passing the puck quickly while sometimes skating at high speeds; making wrist-shots with quick snap; and making slap-shots which launch the puck at high speed. Thus, sticks with various stiffness and flex characteristics are important in player sticks. Typically, forward or offensive players prefer less-stiff (more flexible) shaft response for puck control and wrist-shots with quick snap. Stiffer sticks are generally favored by defense men for slap-shots. In keeping with the difference in purposes of the sticks, the blade of the goalie stick, as shown by Birch, has a horizontal portion and an upstanding portion which is substantially longer than (nearly twice as long as) the horizontal portion. In addition, the upstanding portion of the blade is roughly the same width as the horizontal portion. By contrast, the blade of the player stick has a relatively short upwardly extending portion, mainly for the purpose of providing a transition for connecting to the shaft. This upwardly extending portion is also substantially narrower than the horizontal portion of the player blade. While the Birch shaft is a hollow tube, it is substantially shorter at approximately 32 inches than the shaft of the typical player hockey stick, which is roughly 50 inches, although this varies. Due in part to the relatively long upstanding portion of the goalie blade, a longer shaft is not suitable for use with the goalie stick. The substantially longer shaft of the player stick alone creates a completely different dynamic aspect from that of a goalie stick shaft. As a result of the distinct purpose and the correspondingly different size, the player stick shaft must incorporate various parameters quite distinct from those of the goalie stick shaft. | <SOH> BRIEF SUMMARY OF THE INVENTION <EOH>The present invention provides a player hockey stick shaft comprising an elongated one-piece wall forming a titanium or titanium alloy hollow tube having an upper end and a lower end adapted to receive a player hockey stick blade therein. One embodiment features the wall forming the tube with a thickness ranging from 0.020 to 0.045 inches; and the titanium or titanium alloy having an elastic modulus above 13 million pounds per square inch and a yield strength above 50,000 pounds per square inch. The present invention also provides a player hockey stick shaft comprising an elongated titanium or titanium alloy core having an outer surface, an upper end and a lower end adapted to connect to a player hockey stick blade; and a composite material connected to the outer surface of the core. One embodiment features the core having a wall with a thickness ranging from 0.010 to 0.040 inches and the titanium or titanium alloy having a yield strength above 40,000 pounds per square inch. | 20040329 | 20051018 | 20050929 | 58690.0 | 0 | GRAHAM, MARK S | TITANIUM HOCKEY STICK | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,252 | ACCEPTED | Method and system for management and configuration of remote agents | Method and system for management and configuration of remote agents is provided. At least one web service is provided and at least one remote agent is managed and/or configured based on at least one web service. | 1. A method for management and configuration of remote agents, comprising: providing at least one web service; and performing at least one of managing and configuring at least one remote agent based on at least one web service. 2. The method of claim 1, wherein a at least one remote agent comprises a web service based management interface, wherein the web service based management interface allows a manager to remotely examine and configure at least one remote agent. 3. The method of claim 2 wherein the manager remotely examines and configures at least one remote agent through a central management console. 4. The method of claim 1, wherein at least one remote agent is configured to run across a firewall, a proxy server, and/or a virtual private network. 5. A system for management and configuration of remote agents, comprising: at least one remote agent; and a manager for performing at least one of managing and configuring at least one remote agent based on at least one web service. 6. The system of claim 5, wherein a at least one remote agent comprises a web service based management interface, wherein the web service based management interface allows a manager to remotely examine and configure at least one remote agent. 7. The system of claim 6, wherein the manager remotely examines and configures at least one remote agent through a central management console. 8. The system of claim 5, wherein at least one remote agent is configured to run across a firewall, a proxy server, and/or a virtual private network. 9. A computer readable storage medium including computer executable code for management and configuration of remote agents, comprising: code for providing at least one web service; and code for performing at least one of managing and configuring at least one remote agent based on at least one web service. 10. The computer readable storage medium of claim 9, wherein a at least one remote agent comprises a web service based management interface, wherein the web service based management interface allows a manager to remotely examine and configure at least one remote agent. 11. The computer readable storage medium of claim 10, wherein the manager remotely examines and configures at least one remote agent through a central management console. 12. The computer readable storage medium of claim 9, wherein at least one remote agent is configured to run across a firewall, a proxy server, and/or a virtual private network. | REFERENCE TO RELATED APPLICATIONS The present disclosure is based on and claims the benefit of Provisional Application 60/460,208 filed Apr. 4, 2003, entitled “Web Services Based Discovery of Remote Agents”, 60/460,467 filed Apr. 4, 2003, entitled “SOAP Based Alert Notifications for System Management”, and 60/460,258 filed Apr. 4, 2003, entitled “Web Services Based Management and Configuration of Remote Agents”, the entire contents of which are herein incorporated by reference. BACKGROUND 1. Technical Field The present disclosure relates generally systems management and, more particularly, to a method and system for management and configuration of remote agents. 2. Description of the Related Art Systems management involves the supervision of information technology in an enterprise. System management tools may include two primary elements, agents and managers. The agents are the entities that provide an interface to a device that needs to be managed, such as a server, router, bridge, hub, printer, etc. The device, such as a server, can contain a series of managed objects, such as hardware, configuration parameters, performance statistics, etc. which can all be managed by the agents. The manager can be a user interface to enable a user, such as a network administrator to perform management functions, such as constantly viewing and changing the configuration and status of remote agents. It is useful if users, such as network administrators are able to discover agents and remotely manage them from a central management console through a web based service. In addition, it is useful if managers are able to accurately receive alert notifications to alert them of changes that can occur on an agent system. In globally distributed networks, there is a very high likelihood of a firewall, proxy server, and/or virtual private network (“VPNs”) between the agent nodes and the management console. It is useful if a manager is able to discover, manage and configure a wide variety of agents through a single management console across the firewall, proxy server, and/or VPNs. Simple Network Management Protocol (“SNMP”) is a standard designed to help managers remotely manage devices, such as servers, printers, routers, etc. However, in the presence of a firewall, proxy server, or VPN, SNMP can prove to be unreliable. Accordingly, it would be beneficial to provide a reliable and effective way to ensure that remote agents are able to send alerts to the event console, and are effectively managed and configured. SUMMARY A method for management and configuration of remote agents, according to an embodiment of the present disclosure, includes providing at least one web service, and performing at least one of managing and configuring at least one remote agent based on at least one web service. A system for management and configuration of remote agents, according to an embodiment of the present disclosure, includes at least one remote agent, and a manager for performing at least one of managing and configuring at least one remote agent based on at least one web service. A computer storage medium including computer executable code for management and configuration of remote agents, according to an embodiment of the present disclosure, includes code for providing at least one web service, and code for performing at least one of managing and configuring at least one remote agent based on at least one web service. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: FIG. 1 shows a block diagram of an exemplary computer system capable of implementing the method and system of the present disclosure; FIG. 2 shows a system for agent management, according to an embodiment of the present disclosure; FIG. 3 shows a schematic diagram illustrating the discovery architecture, according to an embodiment of the present disclosure; FIG. 4 shows a flow chart illustrating the sequence of execution of all the operations on a specified target during the discovery process, according to an embodiment of the present disclosure; FIG. 5 shows a block diagram illustrating how the Agent Metadata Service provides metadata to clients; according to an embodiment of the present disclosure; FIG. 6 shows a graphical user interface allowing the user to choose between the two different discovery modes, according to an embodiment of the present disclosure; FIG. 7 shows the second step of the discovery process, in which a graphical user interface is provided allowing the user to select and enter profile information, according to an embodiment of the present disclosure; FIG. 8 shows a graphical user interface allowing a user to perform the third step of entering agent host information, according to an embodiment of the present disclosure; FIG. 9 shows a graphical user interface allowing the user to input proxy details for an agent or manager, according to an embodiment of the present disclosure; FIG. 10 shows a graphical user interface allowing the user to input connection details for an agent or manager, according to an embodiment of the present disclosure; FIG. 11 shows a graphical user interface for verifying security credentials, according to an embodiment of the present disclosure; and FIG. 12 shows a graphical user interface used for presenting a list of discovered agents to a user, according to an embodiment of the present disclosure. DETAILED DESCRIPTION The present disclosure provides tools (in the form of methodologies, apparatuses, and systems) for management and configuration of remote agents. The tools may be embodied in one or more computer programs stored on a computer readable medium or program storage device and/or transmitted via a computer network or other transmission medium. The following exemplary embodiments are set forth to aid in an understanding of the subject matter of this disclosure, but are not intended, and should not be construed, to limit in any way the claims which follow thereafter. Therefore, while specific terminology is employed for the sake of clarity in describing some exemplary embodiments, the present disclosure is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents which operate in a similar manner. FIG. 1 shows an example of a computer system 100 which may implement the method and system of the present disclosure. The system and method of the present disclosure may be implemented in the form of a software application running on a computer system, for example, a mainframe, personal computer (PC), handheld computer, server, etc. The software application may be stored on a recording media locally accessible by the computer system, for example, floppy disk, compact disk, hard disk, etc., or may be remote from the computer system and accessible via a hard wired or wireless connection to a network, for example, a local area network, or the Internet. The computer system 100 can include a central processing unit (CPU) 102, program and data storage devices 104, a printer interface 106, a display unit 108, a (LAN) local area network data transmission controller 110, a LAN interface 112, a network controller 114, an internal bus 116, and one or more input devices 118 (for example, a keyboard, mouse etc.). As shown, the system 100 may be connected to a database 120, via a link 122. According to an embodiment of the present disclosure, a management application (i.e., a manager) can be installed in three components: an agent, which can reside on the same system as the application server; a manager, which can be fully integrated with the management application or can stand alone, and a console, which can provide a user interface. System(s) as referred to herein may include(s) individual computers, servers, computing resources, networks or combinations thereof, etc. Users of the management application can include, application server administrators, system administrators, performance managers, and application server developers, etc. Since the agents and managers may be in a distributed environment, they may be separated by firewalls, proxy servers, and/or VPNs, etc, where SNMP is not a practical communication protocol. According to an embodiment of the present disclosure, a Simple Object Access Protocol (SOAP) is utilized. SOAP is a stateless, one-way message exchange system which can also be utilized to perform request/response, request/multiple responses, etc. in a distributed environment. Discovery is a process of creating a manager side representation of the agent side schema and can touch every layer of the management application. A successful discovery process may be implemented for the administration, configuration and overall successful functioning of the management application. According to an embodiment of the present disclosure, web based agent services can discover any type of remote agent through a single management console, even through firewalls, proxy servers, and/or VPNs, etc. After remote agents are discovered by the management console, a user, such as a system administrator, may constantly view and change the configuration and status of remote agents. Therefore, it is useful if agents are able to be configured to run across firewalls, proxy servers, and/or VPNs, etc. According to an embodiment of the present disclosure, a single management console can manage web based remote agents and can be configured to run across firewalls, proxy servers, and/or VPNs. An agent can have a layout and hierarchy of various types, with each instance representing the various facets of the managed resources, both individual and collective. The discovery process can identify this schema, translate it into a manager side representation compatible with a manager repository, and create the representation in the manager repository, making the data available for various other applications via the repository. Discovery can also include both registering the manager with the agent as a recipient of alert notifications as and when they are raised by the agent and initializing performance data collection for the agent and its objects. A more detailed description of a system for agent management and configuration of remote agents, according to an embodiment of the present disclosure, will be described with reference to FIG. 2. Each agent 212 is a software component capable of monitoring managed objects and reporting their status to a J2EE manager 207 through a communication infrastructure 210. An example of an agent may include, for example, 100 managed objects and can handle XML/character data information. Examples of managed objects are the devices, systems, and/or any hardware or software that require some form of monitoring and management. A managed object can be defined in terms of the attributes it possesses, operations that may be performed on it, and its relationship with other managed objects. According to an embodiment of the present disclosure, a managed object can be a one-to-one mapping to the manageable entities within an application server and its components. The managed objects are described in further detail below. A Service Manager User Interface 202 may, for example, be similar to a “Windows” Service manager and is used to discover and configure the agent, view the status of the managed objects and/or launch reports. The Service Manager User Interface 202 can allow a user to start, stop, and recycle services including, for example, the following manager services: J2EE manager 207, J2EE data collector 208, and J2EE reporter 209 through communication structure 206. J2EE manager 207 can register itself with all discovered agents and can log agent behavior for life cycle management. J2EE manager 207 can have a scheduler to enable timed events and can send out email notifications due to alerts. A user can have the option to collect data and can set a pre-defined collection frequency. J2EE data collector 208 can collect this data for the agents and their objects via agent infrastructure 211. A user can launch reports generated by the J2EE reporter 209 through the Service Manager User Interface 202. J2EE manager 207 and agents 212 can communicate using SOAP through communication infrastructure 210 and the J2EE manager 207 can communicate with the user interface 202 using HTTP through communication infrastructure 206. The Service Manager User Interface 202 can include a management console 203, a management portal 204 and/or a graphical utility 205. The management console 203 can be a java based manager component that displays an event, such as an unsolicited alert notification from a manager or agent indicating, for example, that one of the following conditions may have occurred: a threshold limit was exceeded, the network topology changed, an informational message or error occurred, and/or an application alert occurred, etc. There is no set limit to the number of users that can access the management console 203. The management console 203 can be used to create, update and delete monitored objects. A command line utility can be provided to allow a user to perform all user interface functions from the command line. The management console 203 can be a plug in or can be launched via a right click menu. Agents 212 can be configured through the management console 203 and users can configure the monitoring interval for each object. The current status and value for each selected object can be provided through the management console 203. The management console 203 can also allow a user to enter and edit threshold values, such as, for example, “Warning”, “Major”, and “Critical”. The threshold values can pertain to a threshold level associated with alert notifications. Alert notifications that are of a lower priority value than the threshold value, for example, may not be displayed on the management console 203. The management console 203 can list all registered managers. According to an embodiment of the present disclosure, the type of information that is handled can be XML/character data and the maximum size of the information handled can be 1 K/request. Management portal 204 can provide a web based information management system that provides a single access point for users to share information. For example, a system administrator can use the management portal 204 to access the management console 203 that can be used to manage and configure one or more remote agents. The graphical utility 205 is a manager component that enables a user, such as a system administrator, to configure, browse, and/or edit any agent configuration. The utility can provide an interface to add, remove, and modify objects in the configuration. A common object repository 201 provides other applications with data that is common to all. Discovery may utilize a series of services/modules from the agent and the user interface that assist in the discovery process. FIG. 3 is a schematic diagram illustrating the discovery architecture, according to an embodiment of the present disclosure. The diagram is divided into three parts, where each part represents a layer of the product. The graphical user interface (“GUI”) 205 is used to initiate the discovery process via a discovery wizard 312. The actual discovery is launched by a manager 207 against an agent 212. The Agent Metadata Service 304, Agent Managed Object Query Service 305, and Agent Trap Registration Service 306 are examples of services running on an agent 212. The Agent Metadata Service 304 supports queries to retrieve metadata information residing on the agent 212. The metadata information can include, for example, parent-child relationships between managed objects (“MOs”) and clustered managed objects (“CMOs”), property information of a MO or CMO, and/or information about all events of any given MO or CMO. A more detailed description of the Agent Metadata Service 304 will be provided below. The Agent Managed Object Query Service 305 is used by the Discovery Service 311 and provides information regarding all MO and CMO instances that have been created on the agent 212. The information may include instance properties and properties of some or all events under any instance. The Agent Trap Registration Service 306 is a service used by the Discovery Service 311 and can receive requests for addition, deletion and update of listeners interested in receiving alert notifications that an agent 301 can send. The information used for registration can include parameters to identify the listener uniquely, connection parameters, security credentials, and/or information on proxy servers, if present. The Discovery Service 311, at the end of discovery, can register with the Agent Trap Registration Service 306 to add itself as a listener. The Discovery Service 311, Metadata Cache Service 307, Schema Manager Service 308, Profile Service 309, and Performance Data Collection Service 310 are examples of services running on the manager 207. The Discovery Service 311 is the main service that interacts with other services running on the manager 302 and can receive one or more targets for discovery. A target can be, for example, an agent, a MO, or a CMO. The sequence of execution of operations on a specified target during the discovery process will be described with respect to FIGS. 3 and 4. The Discovery Service 311 first retrieves metadata information from the Metadata Cache Service 307 (Step S401). The Metadata Cache Service 307 can retrieve metadata information during discovery from the Agent Metadata Service 304 and the Schema Manager Service 308 and can cache the information to speed up the discovery process. After retrieval of metadata information, the Discovery Service 311 finds all configured MO and CMO instances on the Agent Managed Object Query Service 305 (Step S402). Data pertaining to the discovered agents is then provided by the Discovery Service 311 to be stored in a database repository through the Schema Manager Service 308 (Step S403). The Schema Manager Service 308 can provide a facade over the database repository which can facilitate addition/deletion/update of agent schema objects into the repository. As part of object creation, the Schema Manager Service 308 can call the Performance Data Collection Service 310 to collect and analyze performance data from the agents, if required (Step S404). The Discovery Service 311 can then register with the Agent Trap Registration Service 306 in order to receive alert notifications from the agents (Step S405). A Profile Service 309 can store the discovery target information as individual discovery profiles, eliminating the need for continuously entering discovery details. A discovery profile may include of one or more targets, allowing a user to create a logical grouping of discovery targets. If a profile contains multiple targets, the profile can be either a discrete list of targets or can be specified by a range of Internet Protocol (IP) addresses. Apart from the host name, or IP addresses, the discovery profile can also contain proxy information used to connect to the host, the connection details, security credentials, and/or a flag indicating whether the profile has been enabled. The Profile Service 309 can supply the Discovery Service 311 with a list of stored profiles and upon request, can be used to create, update, or delete the profiles. The Performance Data Collection Service 310 adds the discovered agent objects for data collection. The Discovery Wizard 312, and Discovery Monitor 313 are graphical user interfaces 205 that interact with Discovery Service 311. The Discovery Wizard 312 provides a user interface to describe the discovery targets by pulling up the existing list of profiles from the Profile Service 309 and displaying them to a user in a tabular format. The user can create new discovery profiles, delete old ones, or update various target fields. The Discovery Wizard 312 can also create a set of discrete target objects from the current profiles and submit the list to the Discovery Service 311. The Discovery Wizard 312 then launches the Discovery Monitor 313, which is a user interface that keeps track of the status and results of the current discovery. The Discovery Monitor 313 indicates to a user if a discovery process is running by continuously polling status and log messages from the Discovery Service 311 and displaying them to the user. When discovery is complete, the Discovery Monitor 313 can display the results of discovery as a tree to the user. The Agent MetaData Service 304 is a SOAP based service on the agent 301 that is used by SOAP clients (e.g., manager 207) to get agent metadata. According to an embodiment of the present disclosure, the following are the data elements for the agent that the Agent Metadata Service 304 can provide to all SOAP clients: Product Name, Product Version, Product Key, Application Server Name, Application Server Version, Build Number, Agent Class Name, Event Class Name, Alerts Class Name, Managed Objects, Managed Object Path, Managed Object Relations, Managed Object Descriptor Properties, Event Set, Event Set Descriptor Properties, Event List, Event Relations, etc. The following methods can be invoked by the Agent Metadata Service 304: “getabout” (can return Product Name, Product Version, Product Key, Application Server Name, Application Server Version, and Build Number); “getAgentCoreClasses” (can return Agent Class Name, Event Class Name, and Alerts Class Name); “getMOList” (can return a list of all managed objects); “getMORelations” (can return a tree structure of all managed object relations); “getMODescriptorProperties” (can return managed object descriptor properties, such as, Name, Nice Name, Description, and other user interface related properties for a managed object); “getPropertySet” (can return a tree structure of managed objects with their properties); “getEventSetList” (can return a list of events for a managed object); “getEventSetDescriptorProperties” (can return managed object descriptor properties, such as, Name, Nice Name, Description, and other user interface related properties for an event set); “getEventList” (can return the list of events in an event set for a managed object); “getEventRelations” (can return a tree structure consisting of event sets and the events for a managed object); “getEventPropertySet” (can return a tree structure consisting of event name as a node and event property name values as attributes). FIG. 5 shows how the Agent Metadata Service 304 provides metadata to SOAP clients (e.g., manager 207). The Agent Metadata Service 304 queries an underlying Managed Object Layer 501 which in turn retrieves data from an XML layer 502 to provide the metadata to the clients. The Discovery Wizard 312 is the graphical user interface 205 that enables a user to access the Discovery Service 311. There are four different common tasks that can be performed for discovery by a user, discovering an agent with valid agent host and agent port, discovering an agent with valid agent host name and port, discovering multiple agents, and updating profiles, each of which will be described in further detail below. A user can discover an agent with a valid agent host and an agent port. According to an embodiment of the present disclosure, a user first chooses one of two modes of operation. FIG. 6 illustrates a GUI allowing the user to choose between the two different discovery modes. The first mode (A) can walk a user through the process of adding a host step by step. The user can then manipulate the list of targets. The second mode (B) can take a user directly to the advanced profile table, where the user can immediately start manipulating the list of targets for discovery. FIG. 7 shows the second step of the discovery process, in which a GUI is provided allowing the user to select a user-friendly name for the discovery profile and enter a profile description. FIG. 8 illustrates a GUI allowing a user to perform the third step of entering the agent host information. Hosts can either be specified by name or by address. There are various ways of specifying multiple hosts. For example, a user can specify a comma-separated list of hosts and addresses or specify an IP address range to discovery by checking the “use range” box. A fourth step in the discovery process involves inputting the proxy details for either an agent or manager. FIG. 9 illustrates a GUI allowing the user to input their information. If a user chooses to enter the agent proxy details, then the user can configure proxy options, if any, for a manager to reach the agent. If a user chooses to enter the manager proxy details, then the user can configure proxy options, if any, for the agent to reach the manager. In case the proxy uses authentication, the user can also supply proxy credentials during this step. A fifth step in the discovery process involves inputting the connection details for either an agent or manager. FIG. 10 illustrates a GUI allowing the user to input this information. If a user chooses to enter the agent connection details, then the user can specify custom communication parameters to be used by the manager in order to reach the agent. If the user chooses to enter the manager connection details, then the user can specify custom communication parameters to be used by the agent in order to reach the manager. For both of these options, the user can specify infinite timeout by checking the requisite box. FIG. 11 illustrates a GUI for entering security credentials. A user can enter the read, write, and execute security credentials on the agent for use by the manager in the discovery and its subsequent interaction with the agent. Various agent interfaces are exposed at various security levels and these credentials can help in providing access control on the agent side. The last step includes displaying a list of discovered agents to a user. The list can contain the agent host entered by the user. FIG. 12 illustrates a GUI used for presenting the information to the user. A user can discover an agent with a valid agent host name and an agent port. This task is similar to the previous task, except that the user chooses the second mode (advanced profile table) in the first step and does not have to enter profile information. A user can discover multiple agents by following the above steps and entering in multiple hosts and ports for the sixth step. To specify multiple hosts, a user can type a comma separated list of machine names for hosts or select the address range check box and specify the range of IP address that are to be discovered. To specify multiple ports, a user can either enter a comma separated list of ports (agent will be discovered using each port number present in the list), specify a range of ports (agent will be discovered using each port number present in the range), or can specify a single port (all agents will be discovered using same port number). All the hosts specified by a user can be displayed in a tabular format. The user can select a particular agent by selecting the row for that agent. The corresponding detailed view for the agent can be shown at the bottom of the selected row. According to an embodiment of the present disclosure, an agent can be a pure Java implementation. An agent can create and monitor real time transactions and synthetic non-intrusive business logic transactions, where the business logic can include object support. An agent can automatically load static and dynamic classes of the application server and can persistently store data. For each metric, an agent can accept user-defined policies, via a user interface to escalate a state (available states can include normal, warning, or critical). When a state is changed within the agent, the agent can send a trap/notification to all its registered managers. A trap/notification is a message sent from an agent to notify another system or alert a manager of changes or events that occur on the agent system. These traps/notifications can be sent using SOAP. According to an embodiment of the present disclosure, an agent can run as a standard windows service and allow a user to execute task/scripts on the server. An agent can also monitor J2EE applications, operating system resources, generic applications, etc. Managed objects are provided for each of these features and are each described in detail below. Managed Objects for Monitoring J2EE Applications 1) Administration Server Managed Object An Administration Server Managed Object can monitor “Access” where the agent sends a “ping” to the administration server to determine if the server is accessible. The Administration Server Managed Object can also monitor the “Most Recent Symptom” found in a log file and the “Log Message Broadcast Rate”, which is the rate per minute at which log messages are being broadcast. 2) Cluster Managed Object A Cluster Managed Object can monitor the following events: “Fragments Sent” (total number of multicast fragments sent from the server into the cluster), “Fragments Sent Rate” (total number of multicast fragments sent from the server into the cluster per minute), “Fragments Received” (total number of multicast messages received on the server from the cluster), “Fragments Received Rate” (total number of multicast messages received on the server from the cluster per minute), “Multicast Messages Lost” (total number of incoming multicast messages that were lost according to the server), “Multicast Messages Lost Rate” (total number of incoming multicast messages that were lost according to the server per minute), “Foreign Fragments Dropped” (number of fragments that originated in foreign domains/cluster that use the same multicast address), “Foreign Fragments Dropped Rate” (number of fragments that originated in foreign domains/cluster that use the same multicast address per minute), “Alive Server” (current total number of alive servers in the cluster), “Resend Requests” (number of state-delta messages that had to be resent because a receiving server in the cluster missed a message), and “# of Primaries” (number of objects that the local server hosts as primaries). 3) Managed Server Managed Object A Managed Server Managed Object can include the following children: a Connection Managed Server Child Managed Object, an Execute Queue Managed Server Child Managed Object, a Thread Managed Server Child Managed Object, each of which will be described in further detail below. The Managed Server Managed Object can monitor “Access” where the agent sends a “ping” to the administration server to determine if the server is available. The Managed Server Managed Object can also monitor the “Most Recent Symptom” found in a log file and the “Log Message Broadcast Rate”, which is the rate per minute at which log messages are being broadcast. The following events can also be supervised by the Managed Server Managed Object: “Heap Size Free” (current heap free), “Heap Size Used” (current size of the heap), “Heap Usage Rate” (heap usage per minute), “Login Attempts While Locked” (cumulative number of invalid logins attempted on the server while the user was locked), “User Lockout” (cumulative number of user lockouts done on the server), “User Lockout Rate” (cumulative number of user lockouts done on the server per minute), “Unlocked Users” (the number of times a user has been unlocked on the server), “Invalid Login Attempts” (cumulative number of invalid logins attempted on the server), “Invalid Login Attempts Rate” (cumulative number of invalid logins attempted on the server per minute), “Invalid Login Users—High” (highwater number of users with outstanding invalid login attempts for the server), “Current Locked Users” (number of currently locked users on the server), “Current Locked Users Rate” (number of currently locked users on the server per minute), Sockets Opened (“total number of sockets opened), “Sockets Opened Rate” (total number of sockets opened per minute), “Restarts” (total number of restarts), “Current Open Sockets” (current number of open sockets), “Current Connections” (current number of connections to the server), “Maximum Connections” (peak number of connections to the server since the last reset), “Total Connections” (total number of connections made to the server since the last reset), “Total Connections Rate” (total number of connections per minute made to the server since the last reset), “Current JMS Servers” (current number of Java Message Servers (JMS) that are deployed on the server instance), “Maximum JMS Servers” (peak number of JMS servers that were deployed on the server instance since the server was started), “Total JMS Servers” (number of JMS servers that were deployed on the server instance since the server was started), “Transactions Rolled Back” (number of transactions that were rolled back), “Transactions Rolled Back Rate” (number of transactions per minute that were rolled back), “Transactions With Heuristics Status Rate” (number of transactions per minute that completed with a heuristic status), “Transactions Rolled Back Due To System Error” (number of transactions that were rolled back due to an internal system error), “Transactions Rolled Back Due To System Error Rate” (number of transactions per minute that were rolled back due to an internal system error), “Transactions Rolled Back Due To Application Error” (number of transactions that were rolled back due to an application error), “Transactions Rolled Back Due To Application Error Rate” (number of transactions per minute that were rolled back due to an application error), “Abandoned Transactions” (number of transactions that were abandoned), “Abandoned Transactions Rate” (number of transactions per minute that were abandoned), “Total Transactions” (total number of transactions processed, including all committed and rolled back and heuristic transaction completions), “Total Transactions Rate” (total number of transactions per minute processed, including all committed and rolled back and heuristic transaction completions), “Transactions Rolled Back Due To Timeout” (number of transactions that were rolled back due to a timeout expiration), “Transactions Rolled Back Due To Timeout Rate” (number of transactions per minute that were rolled back due to a timeout expiration), “Active Transactions” (number of active transactions on the server), “Active Transactions Rate” (number of active transactions per minute on the server), “Transactions Committed” (number of committed transactions), “Transactions Committed Rate” (number of committed transactions per minute), “Transactions Rolled Back Due To Resource Error” (number of transactions that were rolled back due to a resource error), and “Transactions Rolled Back Due to Resource Error Rate” (number of transactions per minute that were rolled back due to a resource error). a) Connection—Managed Server Child Managed Object This Child Managed Object can monitor the following connection events: “Bytes Received Rate” (number of bytes received per minute since the last reset), “Bytes Sent Rate” (number of bytes sent per minute since the last reset), “Messages Received” (number of messages received by the user since the last reset), “Messages Received Rate” (number of messages received per minute by the user since the last reset), “Messages Sent” (number of messages sent by the session since the last reset), and “Messages Sent Rate” (number of messages sent per minute by the session since the last reset). b) Execute Queue—Managed Server Child Managed Object This Child Managed Object can monitor the following performance events: “Pending Requests” (number of waiting requests in the queue), “Serviced Request Total” (number of requests which have been processed by the queue), “Throughput” (number of requests per minute which have been processed by the queue), “Idle Execute Thread” (number of idle threads assigned to the queue), and “Maximum Pending Request Time” (time that the longest waiting request was placed in the queue). c) Thread—Managed Server Child Managed Object This Child Managed Object can monitor the following events: “Total Service Requests” (number of requests which have been processed by the queue), and “Throughput” (number of requests per minute which have been processed by the queue). 4) Servlet Managed Object A Servlet Managed Object can monitor the following events: “Access” (test to determine whether a particular EJB is available), “Total Reloads” (total number of reloads of the servlet), “Average Execution Time” (average amount of time all invocations of the servlet have been executed since created), “Maximum Execution Time” (amount of time the single shortest invocation of the servlet has executed since created), “Minimum Execution Time” (amount of time the single longest invocation of the servlet has executed since created), “Invocation Total” (total number of invocations of the servlet), and “Invocation Total Rate” (total number of invocations of the servlet per minute). 5) EJB Managed Object An EJB Managed Object can monitor the following events: “Access” (test to determine whether a particular EJB is available), “Transactions Rolled Back” (total transactions rolled back), “Transactions Rolled Back Rate” (total transactions rolled back per minute), “Transactions Timed Out” (total transactions timed out), “Transactions Timed Out Rate” (total transactions timed out per minute), “Transactions Committed” (total transactions committed), and “Transactions Committed Rate” (total transactions committed per minute). 6) Entity EJB Managed Object An Entity EJB Managed Object can monitor the following events: “Cache Access” (cache access count), “Cache Access Rate” (cache access count per minute), “Cached Beans Rate” (number of beans currently in cache), “Cache Hit Rate” (cache hit count), “Activation” (number of times the bean instance was activated), “Activation Rate” (number of times the bean instance was activated per minute), “Passivation” (number of times the bean instance was passivated), “Passivation Rate” (number of times the bean instance was passivated per minute), “Current Lock Entries”, “Total Waiters”, “Total Waiter Rate”, “Lock Manager Access”, “Total Timeout”, “Transactions Rolled Back” (total transactions rolled back), “Transactions Rolled Back Rate” (total transactions rolled back per minute), “Transactions Timed Out” (total transactions rolled back per minute), “Transactions Timed Out Rate” (total transactions timed out per minute), “Transactions Committed” (total transactions committed), “Transactions Committed Rate” (total transactions committed per minute), “Total Timeout” (timeout total count), “Beans In Use” (number of beans in use), “Idle Beans” (number of idle beans), and “Waiter Total” (total waiter count). 7) Stateful EJB Managed Object A Stateful EJB Managed Object can monitor the following events: “Cache Access” (cache access count), “Cache Access Rate” (cache access count per minute), “Cached Beans Rate” (number of beans currently in cache), “Cache Hit Rate” (cache hit count), “Activation” (number of times the bean instance was activated), “Activation Rate” (number of times the bean instance was activated per minute), “Passivation” (number of times the bean instance was passivated), “Passivation Rate” (number of times the bean instance was passivated per minute), “Current Lock Entries”, “Total Waiters”, “Total Waiter Rate”, “Lock Manager Access”, “Total Timeout”, “Transactions Rolled Back” (total transactions rolled back), “Transactions Rolled Back Rate” (total transactions rolled back per minute), “Transactions Timed Out” (total transactions rolled back per minute), “Transactions Timed Out Rate” (total transactions timed out per minute), “Transactions Committed” (total transactions committed), and “Transactions Committed Rate” (total transactions committed per minute). 8) Stateless EJB Managed Object A Stateless EJB Managed Object can monitor the following events: “Transactions Rolled Back” (total transactions rolled back), “Transactions Rolled Back Rate” (total transactions rolled back per minute), “Transactions Timed Out” (total transactions timed out), “Transactions Timed Out Rate” (total transactions timed out per minute), “Transactions Committed” (total transactions committed), “Transactions Committed Rate” (total transactions committed per minute), “Total Timeout” (timeout total count), “Beans In Use” (number of beans in use), “Idle Beans” (number of idle beans), and “Waiter Total” (total waiter count). 9) Message EJB Managed Object A Message EJB Managed Object can monitor the following events: “Transactions Rolled Back” (total transactions rolled back), “Transactions Rolled Back Rate” (total transactions rolled back per minute), “Transactions Timed Out” (total transactions timed out), “Transactions Timed Out Rate” (total transactions timed out per minute), “Transactions Committed” (total transactions committed), “Transactions Committed Rate” (total transactions committed per minute), “Total Timeout” (timeout total count), “Beans In Use” (number of beans in use), “Idle Beans” (number of idle beans), and “Waiter Total” (total waiter count). 10) JDBC Managed Object A JDBC Managed Object can monitor the following events: “Access” (test to determine whether the EJB is available), “Active Connections” (current total number of active connections), “Active Connections Rate” (current total number of active connections per minute), “Total Connections” (total number of JDBC connections since the pool is instantiated), “Total Connections Rate” (total number of JDBC connections per minute since the pool is instantiated), “Connection Delay Time” (average time necessary to get a connection from the database), “Waiting For Connection” (current total number waiting for a connection), “Maximum Waiting For Connection” (the high water mark of waiters for a connection), “Failure To Reconnect” (number of cases when a connection pool attempted to refresh a connection to a database and failed), “Failures To Reconnect Rate” (number of cases when a connection pool attempted to refresh a connection to a database and failed per minute), “Maximum Wait In Seconds” (number of seconds the longest waiter for a connection waited), “Leaked Connection” (number of leaked connections), “Leaked Connection Rate” (number of leaked connections per minute), “Prep Statement Cache Miss”, and “Prep Statement Cache Hit”. 11) Connector Connections Managed Object A Connector Connections Managed Object can include a Connector Connection Child Managed Object, which will be described in further detail below. The Connector Connections Managed Object can monitor the following events: “Current Connection” (current total active connections), “Maximum Active Connections” (high water mark of active connections in the Connector Pool since the pool was first instantiated), “Average Usage” (running average usage of created connections that are active in the Connector Pool since the pool was last shrunk), “Total Created” (total number of connector connections created in the Connector Pool since the pool was instantiated), “Total Destroyed Connections” (total number of connector connections destroyed in the Connector Pool since the pool was instantiated), “Total Matched Connections” (total number of times a request for a Connector connections was satisfied via the use of an existing created connection since the pool was instantiated), “Total Rejected Connections” (total number of rejected requests for a Connector connections in the Connector Pool since the pool was instantiated), “Current Connections Free” (current total free connections), “Maximum Connections Free” (high water mark of free connections in the Connector Pool since the pool was instantiated), “Initial Capacity” (initial capacity configured for the Connector connection pool), “Maximum Capacity” (maximum capacity configured for the Connector connection pool), “Total Recycled Connections” (total number of Connector connections that have been recycled in the Connector Pool since the pool was instantiated), “Shrink Count Down” (amount of time left (in minutes) until an attempt to shrink the pool will be made), and “Shrink Period” (the amount of time (in minutes) of the Connector connection pool). a) Connector—Connector Connection Child Managed Object This Child Managed Object can monitor the following connection events: “Active Connection Handles” (current total active connection handles for the connection), “Maximum Active Connection Handles” (high water mark of active connection handles for the connection since the connection was created), and “Total Connection Handles Created” (total number of connection handles created for the connection since the connection was created). 12) Jolt Connections Managed Object A Jolt Connection Managed Object can include a Jolt Connection Child Managed Object, which will be described in further detail below. The Jolt Connection Managed Object can monitor the following event: “Maximum Capacity” (maximum capacity configured for the Connector connection pool). a) Connection—Jolt Connector Managed Object This Child Managed Object can monitor the following connection events: “Error Requests” (current total active connection handles for the connection), “Pending Requests” (pending request count), and “Request Count” (total request count). 13) WLEC Connector Managed Object A WLEC Connector Managed Object can include a WLEC Connector Child Managed Object, which will be described in further detail below. The WLEC Connector Managed Object can monitor the following event: “Maximum Capacity” (maximum capacity configured for the Connector connection pool). a) Connection—WLEC Connector Managed Object This Child Managed Object can monitor the following connection events: “Error Requests” (current total active connection handles for the connection), “Pending Requests” (pending request count), and “Request Count” (total request count). 14) Business Logic Managed Object A Business Logic Managed Object monitors a Content monitor for all server versions. 15) Insider Managed Object An Insider Managed Object monitors the real-time performance of EJBs, servlets, and JDBCs. Managed Objects for Monitoring Operating System Resources 1) Operating System Resources Managed Object An Operating System Resources Managed Object can include a CPU User—Operating System Resources Child Managed Object and a File System—Operating System Resources Child Managed Object, each of which will be described in further detail below. The Operating System Resources Managed Object can monitor the following events: “Available Memory” (real value of available memory), “Available Memory Percent” (percentage value of available memory), “Free Memory” (real value of free memory), “Free Memory Percent” (percentage value of free memory), “Swap Space In Use” (swap space that is currently in use), “Free Swap Space” (swap space that is currently free), and “Paging”. a) CPU User—Operating System Resources Child Managed Object This Child Managed Object can monitor the following CPU User events: “CPU Used” (percentage of CPU used), “Idle Time” (percentage of idle time), “Wait Time” (percentage of wait time), “System Time” (percentage of system time), and “User Time” (percentage of user time). b) File System—Operating System Resources Child Managed Object This Child Managed Object can monitor the following File System events: “Available Disk Space” (currently available disk space), “Available Disk Space Percent” (percentage of currently available disk space), “File Size” (total file size), and “File Size Used” (percentage of file size being utilized. Managed Objects for Monitoring Generic Applications 1) URL Monitor Managed Object A URL Monitor Managed Object can include a File System—Operating System Resources Child Managed Object, which will be described in further detail below. The URL Monitor Managed Object can monitor the following events: “URL Status” (test to check whether URL is accessible), “Content Match” (enter a string of text to check for in the returned page or frameset), “Document Checksum” (a checksum comparison each subsequent time it runs), “Round Trip Time” (total time for the entire request), “DNS Lookup Time” (amount of time to translate the host name to an IP address), “Connect Time” (amount of time to make the connection), “Response Time” (amount of time before the first response was received), “Download Time” (amount of time to receive the page contents), and “Age” (amount of time between the current time and the last modified time for the page). a) File System—Operating System Resources Child Managed Object This Child Managed Object can monitor the following File System events: “Available Disk Space” (currently available disk space), “Available Disk Space Percent” (percentage of currently available disk space), “File Size” (total file size), and “File Size Used” (percentage of file size being utilized. 2) Port Monitor Managed Object A Port Monitor Managed Object can monitor the following events: “Access” (test to check whether the port is accessible or not), and “Time” (time taken to connect to the port). 3) Process Monitor Managed Object A Process Monitor Managed Object can monitor the following events: “Process Size” (real value of the size of the process), “Memory Ratio” (ratio of actual size of the memory occupied by the process to the physical memory on the machine expressed as a percentage), “Number of Threads” (number of threads associated with the process), and “Percent CPU Used” (percent value of the CPU used by the process). 4) HTTP Server Managed Object A HTTP Server Managed Object only monitors the access event for the server. 5) Custom Application Managed Object A Custom Application Managed Object can monitor the TCP Server and log files access events for the server. The specific embodiments described herein are illustrative, and many variations can be introduced on these embodiments without departing from the spirit of the disclosure or from the scope of the appended claims. Elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims. Numerous additional modifications and variations of the present disclosure are possible in view of the above-teachings. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced other than as specifically described herein. | <SOH> BACKGROUND <EOH>1. Technical Field The present disclosure relates generally systems management and, more particularly, to a method and system for management and configuration of remote agents. 2. Description of the Related Art Systems management involves the supervision of information technology in an enterprise. System management tools may include two primary elements, agents and managers. The agents are the entities that provide an interface to a device that needs to be managed, such as a server, router, bridge, hub, printer, etc. The device, such as a server, can contain a series of managed objects, such as hardware, configuration parameters, performance statistics, etc. which can all be managed by the agents. The manager can be a user interface to enable a user, such as a network administrator to perform management functions, such as constantly viewing and changing the configuration and status of remote agents. It is useful if users, such as network administrators are able to discover agents and remotely manage them from a central management console through a web based service. In addition, it is useful if managers are able to accurately receive alert notifications to alert them of changes that can occur on an agent system. In globally distributed networks, there is a very high likelihood of a firewall, proxy server, and/or virtual private network (“VPNs”) between the agent nodes and the management console. It is useful if a manager is able to discover, manage and configure a wide variety of agents through a single management console across the firewall, proxy server, and/or VPNs. Simple Network Management Protocol (“SNMP”) is a standard designed to help managers remotely manage devices, such as servers, printers, routers, etc. However, in the presence of a firewall, proxy server, or VPN, SNMP can prove to be unreliable. Accordingly, it would be beneficial to provide a reliable and effective way to ensure that remote agents are able to send alerts to the event console, and are effectively managed and configured. | <SOH> SUMMARY <EOH>A method for management and configuration of remote agents, according to an embodiment of the present disclosure, includes providing at least one web service, and performing at least one of managing and configuring at least one remote agent based on at least one web service. A system for management and configuration of remote agents, according to an embodiment of the present disclosure, includes at least one remote agent, and a manager for performing at least one of managing and configuring at least one remote agent based on at least one web service. A computer storage medium including computer executable code for management and configuration of remote agents, according to an embodiment of the present disclosure, includes code for providing at least one web service, and code for performing at least one of managing and configuring at least one remote agent based on at least one web service. | 20040330 | 20100504 | 20050526 | 71338.0 | 0 | POLLACK, MELVIN H | METHOD AND SYSTEM FOR MANAGEMENT AND CONFIGURATION OF REMOTE AGENTS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,363 | ACCEPTED | Transceiver device with a transmit clock signal phase that is phase-locked with a receiver clock signal phase | A transceiver system is disclosed that includes a plurality of transceiver chips. Each transceiver chip includes one or more SERDES cores. Each SERDES core includes one or more SERDES lanes. Each SERDES lane includes a receive channel and a transmit channel. The transmit channel of each SERDES lane is phase-locked with a corresponding receive channel. The transceiver system has the capability of phase-locking a transmit clock signal phase of a transmitting component with a receive clock signal phase of a receiving component that is a part of a different SERDES lane, a different SERDES core, a different substrate, or even a different board. Each SERDES core receives and transmits data to and from external components connected to the SERDES core, such as hard disk drives. A method of transferring data from a first external component coupled to a receive channel to a second external component coupled to a transmit channel is also disclosed. | 1. A transceiver system comprising: a plurality of transceiver chips, each transceiver chip having a plurality of serializer/deserializer (SERDES) cores, each SERDES core having one or more SERDES lanes, each SERDES lane having a receive channel and a transmit channel, wherein the transmit channel of each SERDES lane is phase-locked with a corresponding receive channel. 2. The transceiver system of claim 1, wherein each SERDES core receives and transmits data to and from external components connected to the SERDES core. 3. The transceiver system of claim 2, wherein the external components include disk drives. 4. The transceiver system of claim 1, wherein the transmit channel and the corresponding receive channel are each part of a common SERDES lane. 5. The transceiver system of claim 1, wherein the transmit channel is part of a first SERDES lane of a common SERDES core, and the corresponding receive channel is part of a second SERDES lane of the common SERDES core. 6. The transceiver system of claim 1, wherein the transmit channel is part of a first SERDES lane of a first SERDES core, and the corresponding receive channel is part of a second SERDES lane of a second SERDES core. 7. The transceiver system of claim 6, wherein the first SERDES core and the second SERDES core are disposed on a common substrate. 8. The transceiver system of claim 6, wherein the first SERDES core is disposed on a first substrate and the second SERDES core is disposed on a second substrate. 9. The transceiver system of claim 8, wherein the first substrate and the second substrate are disposed on a common board. 10. The transceiver system of claim 8, wherein the first substrate is disposed on a first board and the second substrate is disposed on a second board. 11. A method of transferring data from a first external component coupled to an active receive channel of a transceiver system to a second external component coupled to an active transmit channel of the transceiver system, in which a transmit clock signal of the active transmit channel is phase-locked with a receive clock signal of the active receive channel, the transceiver system comprising a plurality of transceiver chips, each transceiver chip having a plurality of serializer/deserializer (SERDES) cores, each SERDES core having one or more SERDES lanes, each SERDES lane having a receive channel and a transmit channel, the method comprising: receiving, at the active receive channel, external component data from the first external component; transferring the external component data and receive clock phase data from the active receive channel to the active transmit channel; phase-locking the transmit clock signal with the receive clock signal per the receive clock phase data; and transmitting, from the active transmit channel, the external component data to the second external component. 12. The method of claim 11, wherein the first and second external components include disk drives. 13. The method of claim 11, wherein: the receiving step receives the external component data in analog format; the transferring step transfers the external component data and receive clock signal phase data in digital format; and the transmitting step transmits the external component data in analog format. 14. The method of claim 11, wherein: the receiving step receives the external component data in series; the transferring step transfers the external component data and receive clock signal phase data in parallel; and the transmitting step transmits the external component data in series. 15. The method of claim 11, wherein the active transmit channel and the active receive channel are each part of a common SERDES lane. 16. The method of claim 11, wherein the active transmit channel is part of a first SERDES lane of a common SERDES core, and the active receive channel is part of a second SERDES lane of the common SERDES core. 17. The method of claim 11, wherein the active transmit channel is part of a first SERDES lane of a first SERDES core, and the active receive channel is part of a second SERDES lane of a second SERDES core. 18. The method of claim 17, wherein the first SERDES core and the second SERDES core are disposed on a common substrate. 19. The method claim 17, wherein the first SERDES core is disposed on a first substrate and the second SERDES core is disposed on a second substrate. 20. The method of claim 19, wherein the first substrate and the second substrate are disposed on a common board. 21. The method of claim 19, wherein the first substrate is disposed on a first board and the second substrate is disposed on a second board. | CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 60/540,295, filed Jan. 30, 2004, the contents of which is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to transceiver devices. More particularly, this invention relates to serializer/deserializer (SERDES) components of a transceiver device, and the phase-locking of a transmit clock signal phase with a receive clock signal phase. 2. Related Art A serializer/deserializer (SERDES) device converts received high-speed serial data into low-speed parallel data at a receiver. The parallel data may then be processed and then passed to a transmitter. At the transmitter, the low-speed parallel data is converted back into high-speed serial data for transmission out of the SERDES device. A SERDES device is used to control external devices, or used as a repeater, allowing data from one external device, such as a disk drive, to be transferred to another external device. For example, the external devices may be disk drives that include identical data, providing a back-up mechanism in the event that one disk drive fails. As another example, the external devices may be individual disk drives that, as a group, form one or more databases. A SERDES device may include a plurality of SERDES cores. Each SERDES core may include one or more receiver/transmitter pairs. Multiple SERDES cores may be daisy-chained together such that data received by one core may be transmitted by another core. Communication between a receiver and a transmitter of a SERDES device involves high-speed clocks. A typical mode of operation in a SERDES device is a repeat mode in which the transmit data frequency needs to track the receiver data frequency in order to preserve data integrity. This operation must be performed at the receiver without having to retime the recovered clock to the local clock. For high-speed communication, one typically needs to have very well-matched clocks, especially if transferring data between SERDES cores on different substrates (e.g., chips) or boards. For example, if transferring data from a receiver on one SERDES core to a transmitter on another SERDES core, the clocks between the receiver and the transmitter should be matched in order to sample the data at the right time. If the clocks are not matched, the frequency difference between the two clocks will drift over time, resulting in what appears to be an extra pulse or a missing pulse. This frequency drift will eventually cause a loss of data integrity. One solution is to use a common clock at the receiver and the transmitter. However, on today's large and complicated systems, it is not practical to run high-frequency lines between every receiver and transmitter. Furthermore, although electronic components are very small, there is a relatively large distance between them. It may not be feasible to maintain a common clock over such a distance. For similar reasons, it may not be feasible to maintain direct clock-matching over such a distance. SERDES devices that work at much slower speeds and do not link many devices together may not have a frequency drift issue. For example, SERDES devices that work at about 2.5 Gigahertz may not have a frequency drift issue. However, more modern SERDES devices work at 4 Gigahertz or more. In a transceiver, there is typically a digital portion and an analog portion. When synchronizing a transmitter clock to a receiver clock, and jumping from one frequency to another frequency, instability of the system and loss of data integrity may occur on the analog side. Furthermore, if the frequency change is too large, the new clock pulse width may be larger than the minimum clock pulse width required on the digital side. It is important to prevent large frequency changes such as that just described in order to preserve data integrity and prevent system errors. What is needed is a high-speed SERDES transceiver device in which a transmitter clock signal is synchronized with a receiver clock signal without the frequency drift problems described above. Furthermore, what is needed is the capability to synchronize a transmitter clock signal with a receiver clock signal of a receiving component that is part of a different SERDES core, a different substrate, or even a different board, without the frequency drift problems such as those described above. What is also needed is a mechanism to prevent transmitter clock frequency changes that are so large as to violate a minimum pulse width required by a receiver. SUMMARY OF THE INVENTION A transceiver system is disclosed that includes a plurality of transceiver chips. Each transceiver chip includes one or more SERDES cores. Each SERDES core includes one or more SERDES lanes. Each SERDES lane includes a receive channel and a transmit channel. The transmit channel of each SERDES lane is phase-locked with a corresponding receive channel. According to an embodiment of the present invention, each SERDES core receives and transmits data to and from external components connected to the SERDES core. In an embodiment, the external components include disk drives, such as hard disk drives, or removable media drives (e.g., a compact disc drive). The external components may also include databases or other media formats that contain, manipulate, or transfer data. According to an embodiment of the present invention, the transmit channel and the corresponding receive channel are each part of a common SERDES lane. In another embodiment, the transmit channel is part of a first SERDES lane of a common SERDES core, and the corresponding receive channel is part of a second SERDES lane of the common SERDES core. In a further embodiment, the transmit channel is part of a first SERDES core, and the corresponding receive channel is part of a second SERDES core. According to an embodiment of the present invention, the first SERDES core and the second SERDES core are disposed on a common substrate. In another embodiment, the first SERDES core is disposed on a first substrate and the second SERDES core is disposed on a second substrate. In one embodiment, the first substrate and the second substrate are disposed on a common board. In another embodiment, the first substrate is disposed on a first board, and the second substrate is disposed on a second board. A method of transferring data from a first external component coupled to an active receive channel of a transceiver system to a second external component coupled to an active transmit channel of the transceiver system is also disclosed. The transceiver system is that of the various embodiments described above. The external components include, but are not limited to, disk drives. The method includes receiving external component data from the first external component, transferring the external component data and receive clock phase data from the active receive channel to the active transmit channel, phase-locking the transmit clock signal with the receive clock signal per the receive clock phase data, and transmitting the external component data to the second external component. According to an embodiment of the present invention, the receiving step receives the external component data in analog format, the transferring step transfers the external component data and receive clock signal phase data in digital format, and the transmitting step transmits the external component data in analog format. According to another embodiment of the present invention, the receiving step receives the external component data in series, the transferring step transfers the external component data and receive clock signal phase data in parallel, and the transmitting step transmits the external component data in series. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. FIG. 1 illustrates an exemplary multiple-core SERDES device connected to a plurality of external components. FIG. 2 illustrates a more detailed view of an exemplary multiple-core SERDES device. FIG. 3 illustrates an exemplary view of the receiving of analog data by a receiver of a SERDES core, the transferring of the parallel data and clock information to a transmitter of a SERDES core, and the transmission of analog data from the transmitter out of the SERDES core. FIG. 4 illustrates an exemplary view of intralane transfer of data between a receiver and transmitter of a common lane of a SERDES core. FIG. 5A illustrates an exemplary view of interlane transfer of data between a receiver and a transmitter of different lanes of a SERDES core. FIG. 5B illustrates an exemplary view of interlane/intercore transfer of data between a receiver and a transmitter of different SERDES cores. FIG. 6A illustrates an exemplary view of intralane transfer of data between a receiver and transmitter of a common lane of a SERDES core. FIG. 6B illustrates an exemplary view of interlane transfer of data between a receiver and a transmitter of different lanes of a SERDES core. FIG. 6C illustrates an exemplary view of interlane/intercore transfer of data between a receiver and a transmitter of different SERDES cores on a single substrate. FIG. 6D illustrates an exemplary view of interlane/intercore transfer of data between a receiver and a transmitter of different SERDES cores disposed on different substrates of a single board. FIG. 6E illustrates an exemplary view of interlane/intercore transfer of data between a receiver and a transmitter of different SERDES cores disposed on different substrates of different boards. FIG. 7A illustrates the sixty-four (64) possible phases available during a clock cycle for a clock signal, according to an embodiment of the present invention. FIG. 7B illustrates, in dial format, the sixty-four (64) possible phases available during a clock cycle for a clock signal, according to an embodiment of the present invention. FIG. 8 illustrates an exemplary view of the transfer of a receive clock phase delta and direction from a receiver to a transmitter, according to an embodiment of the present invention. FIG. 9 illustrates an exemplary bit allocation for transferring a receive clock phase difference (delta) and direction. FIG. 10 illustrates an exemplary view of the transfer of a previous receive clock phase and a current receive clock phase from a receiver to a transmitter, according to an embodiment of the present invention. FIG. 11 illustrates a more detailed view of the transfer of a receive clock phase data from a receiver to a transmitter, according to an embodiment of the present invention. FIG. 12 illustrates another more detailed view of the transfer of a receive clock phase data from a receiver to a transmitter, according to another embodiment of the present invention. FIG. 13A illustrates a detailed view of the phase calculator depicted in FIG. 12, according to an embodiment of the present invention. FIG. 13B illustrates another detailed view of the phase calculator depicted in FIG. 12, according to an embodiment of the present invention. FIG. 14 illustrates a more detailed view of component 1388 of the phase calculator depicted in FIG. 13B, according to an embodiment of the present invention. FIG. 15 depicts a flowchart of a method of synchronizing a receive clock signal phase with a transmit clock signal phase, according to an embodiment of the present invention. FIG. 16 depicts a flowchart of a method of synchronizing a receive clock signal phase with a transmit clock signal phase, according to another embodiment of the present invention in which a phase difference and direction is provided to a transmitter. FIG. 17 depicts a flowchart of the adjusting step of FIG. 16, according to an embodiment of the present invention. FIG. 18 depicts a flowchart of a method of synchronizing a receive clock signal phase with a transmit clock signal phase, according to a further embodiment of the present invention in which a previous receive clock signal phase and a current receive clock signal phase is provided to a transmitter. FIG. 19 depicts a flowchart of the providing step of FIG. 18, according to an embodiment of the present invention. FIG. 20 depicts a flowchart of the adjusting step of FIG. 18, according to an embodiment of the present invention. FIG. 21 depicts a flowchart of a method of phase-locking a transmit clock signal phase with a receive clock signal phase, according to an embodiment of the present invention. FIGS. 22A and 22B depict a flowchart of a method of phase-locking a transmit clock signal phase with a receive clock signal phase, according to another embodiment of the present invention in which control signals are used to limit phase adjustment. FIG. 23 depicts a flowchart of a method of transferring data from a first external component to a second external component using a transceiver system such as disclosed herein, according to an embodiment of the present invention. The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. DETAILED DESCRIPTION OF THE INVENTION While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. FIG. 1 illustrates an exemplary SERDES system 100, including a single SERDES chip 102 that communicates with a plurality of external components 104 through corresponding transmission and receive lines, serial high speed interface 106. External components 104 may include any combination of external devices such as disk drives or databases. SERDES chip 102 includes three SERDES cores 108, 110, 112. Each SERDES core can communicate with any other SERDES core, as indicated by lines 114. Fiber channel PCS 116 includes internal buses, control logic, and a switching mechanism that need not be discussed herein. SERDES cores 108, 110, 112 and fiber channel PCS 116 are connected through a parallel interface. A SERDES chip, such as SERDES chip 102, may include any number of SERDES cores, and is not to be limited to the three shown in SERDES chip 102. Similarly, the number of external components 104 coupled to SERDES chip 102 can be up to the number that the total number of SERDES cores can handle, as will be discussed in more detail below with reference to FIG. 2. FIG. 2 illustrates SERDES chip 102, depicting more detail in the SERDES cores 108, 110, 112. Each SERDES core includes a plurality of communication lanes, and each lane includes a receive channel and a transmit channel. For example, SERDES core 112 includes a plurality of communication lanes, such as lane 220. Lane 220 includes receive channel 222 and transmit channel 224 that are coupled to one of external components 104 of FIG. 1. Receive channel 222 can receive data from the external component 104 of FIG. 1 to which it is coupled. Alternatively, receive channel 222 can receive data from another SERDES core on the same chip or from another chip, such as chip 226. In this way, FIG. 2 depicts a SERDES system 200 that includes daisy-chained SERDES chips 102 and 226. Receive channel 222 of chip 102 receives data from transmit channel 228 of chip 226, and receive channel 230 of chip 226 receives data from transmit channel 224 of chip 102. FIG. 3 illustrates an exemplary view of a receive channel and a transmit channel of a SERDES core coupled to an external component. The receive channel and transmit channel may be part of a common communication lane, or may be part of different communication lanes. For exemplary purposes, assume FIG. 3 depicts receive channel 222 and transmit channel 224 of SERDES core 112 of FIG. 2. Analog data is transmitted in serial as receive signal 332 to receive channel 222. The analog data of receive signal 332 comes directly from an external component, such as one of external components 104 (of FIG. 1) that is coupled to receive channel 222. The external component 104 transmits data in analog format, as depicted by arrow 338. Once received by SERDES core 112, the data is converted and handled digitally, as depicted by arrow 336. A timing recovery module 340 prepares receive clock information for transfer to transmit channel 224. Received and digitized data 344 and the receive clock information 342 are transferred in parallel from receive channel 222 to transmit channel 224. The transmit channel synchronizes the transmit clock to the receive clock per receive clock information 342 in order to preserve the integrity of data 344. The digitized data 344 is then converted to analog data and transmitted from transmit channel 224 as a transmit signal 334. Transmit signal 334 is received by the external component 104 (of FIG. 1) that is coupled to transmit channel 224. An intralane transfer is depicted in FIG. 4. For an interlane transfer, data received at a receive channel may be transferred to and transmitted from a transmit channel of a common communication lane of a SERDES core. In FIG. 4, receive channel 450 transfers data to transmit channel 452 of a common communication lane 454 of a SERDES core. In the alternative, data received at a receive channel may be transferred to and transmitted from a transmit channel of a different communication lane. This is called interlane transfer and is depicted in FIGS. 5A and 5B. In FIG. 5A, receive channel 556 transfers data to transmit channel 558 of a different communication lane of a common SERDES core. In FIG. 5B, receive channel 560 of SERDES core 562 transfers data to transmit channel 564 of SERDES core 566. Because receive channel 560 of SERDES core 562 transfers data to a transmit channel of a different SERDES core, this is called interlane/intercore transfer. In embodiments, the interlane/intercore transfer can even be performed over different substrates. FIGS. 6A-6E illustrate intralane and interlane transfers in slightly more detail. FIG. 6A depicts an example of intralane transfer in which a receive channel 667 transfers data to a transmit channel 668 of a common communication lane 669 of a single SERDES core 670. FIGS. 6B-6E depict examples of interlane transfers. In FIG. 6B, a receive channel 671 transfers data to a transmit channel 672 of a different communication lane of a common SERDES core 673. In FIG. 6C, a receive channel 674 of a SERDES core 675 transfers data to a transmit channel 676 of a SERDES core 677, where SERDES cores 675 and 677 are disposed on a common substrate 678 (an interlane/intercore transfer). In FIG. 6D, a receive channel 679 of a SERDES core 680 transfers data to a transmit channel 682 of a SERDES core 683 (an interlane/intercore transfer), where SERDES cores 680 is disposed on a substrate 681 and SERDES core 683 is disposed on a substrate 684 of a common board 685. In FIG. 6E, a receive channel 686 of a SERDES core 687, disposed on a substrate 688, transfers data to a transmit channel 690 of a SERDES core 691 (an interlane/intercore transfer), disposed on a substrate 692, where substrate 688 is disposed on a board 689 and substrate 692 is disposed on a board 693. FIGS. 6D and 6E are examples of chips and boards, respectively, daisy-chained together for flexibility of communication between more external components, such as external components 104 of FIG. 1. The present invention synchronizes a transmit clock signal with a receive clock signal by synchronizing the phases of the transmit clock signal with the receive clock signal. According to the present invention, a single clock cycle is made up of a total of P equally offset phases, phase 0 to phase P-1, as depicted in FIG. 7A. The phases can also be depicted in dial format as shown in FIG. 7B. For example if a clock cycle is defined as having 64 phases (i.e., P=64), then phase 795 of FIG. 7A would be defined as phase 64−1, or phase 63. Similarly, in FIG. 7B, phase 796 would be defined as phase 64/4−1=phase 15, phase 797 would be defined as 64/2−1=phase 31, phase 798 would be defined as 3*64/4−1=phase 47, and phase 799 would be defined as 64−1=phase 63. The purpose of depicting clock signal phases in this manner will become apparent in the description to follow. In the previous description with reference to FIG. 3, it was stated that received and digitized data 344 and receive clock information 342 is transferred in parallel from receive channel 222 to transmit channel 224. According to an embodiment of the present invention, the receive clock information 342 includes a receive clock phase difference between a current receive clock signal phase and a previous receive clock signal phase. The previous receive clock signal phase is delayed in time from the current receive clock signal phase by one cycle of time, for example. In this embodiment, the receive clock information 342 also includes a direction of the receive clock phase difference. FIG. 8 illustrates the transfer 806 of a receive clock phase difference and a direction from receive channel 802 to transmit channel 804. The retiming module 808 of transmit channel 804 adjusts the transmit clock signal phase based on the receive clock phase difference and direction, in order to synchronize the receive and transmit clocks and ensure the integrity of the data transferred out from transmit channel 804. The receive clock phase difference and direction are determined at the timing recovery module 809 of receive channel 802. The receive clock phase difference is the difference between a current receive clock signal phase and a previous receive clock signal phase. The direction is an indication of whether the transmit clock signal phase is to be adjusted forward or backward by the receive clock phase difference. For example, if the receive clock phase difference is determined to be 16, and the direction is determined to be backward, then in a 64-phase system in which a current transmit clock signal phase is 15, then an adjusted transmit clock signal phase would start at phase 15 (located at phase 796 of FIG. 7B) and move backward (i.e., counter-clockwise) on the dial of FIG. 7B by 16 phases, resulting in an adjusted transmit clock signal phase of 63 (located at phase 799 of FIG. 7B). In an embodiment of the present invention, the transfer of the receive clock phase difference and direction is accomplished with an N-bit sequence 900 as depicted in FIG. 9. The first N−1 bits 910 of bit sequence 900 indicate the phase difference, and the Nth bit 912 indicates the direction. Using the information provided in the previous example, if in a 64-phase system the receive clock phase difference is determined to be 16, then bits 910 would include six bits in the following sequence: 010000. In one embodiment, a one (‘1’) in bit 912 indicates a direction of forward, and a zero (‘0’) in bit 912 indicates a direction of backward. In another embodiment, a zero (‘0’) in bit 912 indicates a direction of forward, and a one (‘1’) in bit 912 indicates a direction of backward. According to an alternative embodiment of the present invention, the receive clock information 342 includes a previous receive clock signal phase and a current receive clock signal phase. FIG. 10 illustrates the transfer 1014 of a previous receive clock signal phase and a current receive clock signal phase from receive channel 1016 to transmit channel 1018. The retiming module 1020 of transmit channel 1018 adjusts the transmit clock signal phase based on previous receive clock signal phase and a current receive clock signal phase, in order to synchronize the receive and transmit clocks and ensure the integrity of the data transferred out from transmit channel 1018. To do this, retiming module 1020 includes a phase calculator 1022. FIG. 11 depicts a more detailed view of the system depicted in FIGS. 8 and 10. Serial data 1124 is received by a receive channel 1126 from either an external component, such as one of external components 104, or from a transmit channel. Receive channel 1126 includes an analog receive serializer 1128 and a timing recovery module 1132. The serial data 1124 is put into digital format by analog receive serializer 1128, creating digitized data 1130. Timing recovery module 1132 receives a receive clock signal 1134 and determines a phase difference between the phase of the current receive clock signal 1134 and a stored previous receive clock signal phase. The timing recovery module also determines a direction of the phase difference between the phase of the current receive clock signal 1134 and the stored previous receive clock signal phase, as described earlier with reference to FIG. 8. The timing recovery module then outputs the phase difference and direction as receive clock phase data 1136. In an embodiment of the present invention, the receive clock phase data 1136 is output in the N-bit sequence format as described earlier with reference to FIG. 9. Other formats are also possible, as would be appreciated by those skilled in the art. On a receive clock signal pulse, the digitized data 1130, the current receive clock signal 1134 and the receive clock phase data 1136 are transferred in parallel to transmit channel 1138. Transmit channel 1138 includes an analog transmit serializer 1140 and a retiming first-in-first-out register (FIFO)/phase calculator 1142. Retiming FIFO/phase calculator 1142 has the role of retiming module 808 as previously described in reference to FIG. 8. On a receive clock pulse, retiming FIFO/phase calculator 1142 receives and writes digitized data 1130, current receive clock signal 1134 and receive clock phase data 1136 from receive channel 1126. Retiming FIFO/phase calculator 1142 also receives a transmit clock signal 1144. On a transmit clock signal pulse, retiming FIFO/phase calculator 1142 determines a new transmit clock phase 1146 based on the receive clock phase data 1136, and outputs the new transmit clock phase 1146 and the digitized data 1148. The analog transmit serializer 1140 receives the new transmit clock phase 1146 and the digitized data 1148. The analog transmit serializer 1140 places the digitized data 1148 into analog format and adjusts the transmit clock signal based on the new transmit clock phase 1146. On an adjusted transmit clock signal pulse, serial data 1150 is output from transmit channel 1138. FIG. 12 depicts a slightly more detailed view of the system depicted in FIG. 11. The description of the components and role receive channel 1126 in FIG. 12 is similar to that of the description provided above with reference to FIG. 11. Similar to the description of FIG. 11, on a receive clock signal pulse, the digitized data 1130, the current receive clock signal 1134 and the receive clock phase data 1136 are transferred in parallel to transmit channel 1238. Transmit channel 1238 includes an analog transmit serializer 1240 and a retiming module 1242. Retiming module 1242 has the role of retiming module 808 and 1020 as previously described in reference to FIGS. 8 and 10. Retiming module 1242 includes a first-in-first-out register 1260 and a phase calculator 1262. On a receive clock pulse, retiming module 1242 receives and writes digitized data 1130, current receive clock signal 1134 and receive clock phase data 1136 from receive channel 1126 to FIFO register 1260. FIFO register 1260 also receives a transmit clock signal 1244. On a transmit clock signal pulse, FIFO register 1260 outputs digitized data 1248 and phase calculation data 1236, which includes current receive clock signal 1134, receive clock phase data 1136, and transmit clock signal 1244. Phase calculator 1262 receives the phase calculation data 1236 and determines and outputs a new transmit clock phase 1246 based on the phase calculation data 1236. The analog transmit serializer 1240 receives the new transmit clock phase 1246 and the digitized data 1248. The analog transmit serializer 1240 places the digitized data 1248 into analog format and adjusts the transmit clock signal based on the new transmit clock phase 1246. On an adjusted transmit clock signal pulse, serial data 1250 is output from transmit channel 1238. FIG. 13A is a more detailed view of phase calculator 1262, according to an embodiment of the present invention. Phase calculator 1262 includes a phase difference calculator 1366, a phase control multiplexer 1368, and an add delta module 1370. Phase difference calculator 1366 receives a current receive clock signal phase 1372 from FIFO register 1260 and a previous receive clock signal phase 1374. Previous receive clock signal phase 1374 is provided by a delay element register 1396, based on a previously stored current receive clock signal phase 1372. Phase difference calculator 1366 determines a calculated phase difference 1376. In an embodiment, the calculated phase difference 1376 includes both a phase difference and a direction, as described above. Phase control multiplexer 1368 receives the calculated phase difference 1376, a predetermined phase difference (including direction) 1378, and a select phase control signal 1380. In an embodiment of the present invention, the predetermined phase difference 1378 is determined at receiving channel 1126, provided to transmit channel 1238 as receive clock phase data 1136, and provided to phase difference calculator 1366 as part of phase calculation data 1236. Phase control multiplexer 1368 selects either calculated phase difference 1376 or predetermined phase difference 1378 depending on the select phase control signal 1380. Phase control multiplexer then outputs either the calculated phase difference 1376 or predetermined phase difference 1378 as phase adjustment value 1382. In an embodiment, add delta module 1370 receives phase adjustment value 1382 and a previous transmit clock signal phase 1384. The add delta module 1370 determines a new transmit phase value 1386 based on phase adjustment value 1382 and previous transmit clock signal phase 1384. New transmit phase value 1386 is fed back to delay element register 1394 for the next cycle, in which previous transmit clock signal phase 1384 is provided by delay element register 1394. According to an embodiment of the present invention, phase calculator 1262 also optionally includes an adjust decision module 1388, as shown in FIG. 13B. In an embodiment of the present invention, adjust decision module 1388 receives a phase threshold 1395 and a phase limit signal 1389, as well as phase adjustment value 1382. Phase limit signal 1389 signifies whether the phase should be limited to a threshold or not. Adjust decision module 1388 determines whether phase adjustment value 1382 exceeds predetermined phase threshold 1395, and outputs decision signal 1390 to a zero/adjustment multiplexer 1391 accordingly, depending on phase limit signal 1389. For example, if phase limit signal 1389 signifies that the phase should be limited to a threshold, and adjust decision module 1388 determines that phase adjustment value 1382 exceeds predetermined phase threshold 1395, then decision signal 1390 signifies that no adjustment is to be made. As another example, if phase limit signal 1389 signifies that the phase should be limited to a threshold, and adjust decision module 1388 determines that phase adjustment value 1382 does not exceed predetermined phase threshold 1395, then decision signal 1390 signifies that a phase adjustment is to be made. As a third example, if phase limit signal 1389 signifies that the phase should not be limited to a threshold, then decision signal 1390 signifies that a phase adjustment is to be made, regardless of whether phase threshold 1395 is exceeded. Zero/adjustment multiplexer 1391 receives decision signal 1390, phase adjustment value 1382, and a zero adjustment value 1392 (i.e., a value of zero). Zero/adjustment multiplexer 1391 selects zero adjustment value 1392 if decision signal 1390 signifies that a phase adjustment is not to be made. Alternatively, zero/adjustment multiplexer 1391 selects phase adjustment value 1382 if decision signal 1390 signifies that a phase adjustment is to be made. A zero/adjustment selection 1397 made by zero/adjustment multiplexer 1391 is output to add delta module 1370. If zero adjustment value 1392 is selected, add delta module 1370 adds a value of zero to the previous transmit clock signal phase 1384, resulting in a new transmit phase value 1386 equaling the previous transmit clock signal phase 1384. In effect, when this occurs, the transmit clock signal phase is not adjusted. If instead phase adjustment value 1382 is selected, add delta module 1370 adds or subtracts (depending on the specified direction) phase adjustment value 1382 to/from the previous transmit clock signal phase 1384, resulting in a new transmit phase value 1386. According to another embodiment of the present invention, adjust decision module 1388 receives a transmit phase lock signal 1393. The adjust decision module 1388 determines whether transmit phase lock signal 1393 signifies that a transmit phase lock is set (i.e., that the phase is not to be adjusted). It may be desired for a transmit phase lock to be set if data is switched from one lane to another (e.g., when receive data is switched from one transmit lane to another transmit lane). If adjust decision module 1388 determines from transmit phase lock signal 1393 that a transmit phase lock is set, then adjust decision module 1388 outputs decision signal 1390 to zero/adjustment multiplexer 1391 signifying that no phase adjustment is to be made. Alternatively, if adjust decision module 1388 determines from transmit phase lock signal 1393 that a transmit phase lock is not set, then adjust decision module 1388 outputs decision signal 1390 to zero/adjustment multiplexer 1391 signifying that a phase adjustment is to be made (assuming there is no phase threshold limitation). As in the previous embodiment involving a phase threshold limitation, zero/adjustment multiplexer 1391 receives decision signal 1390, phase adjustment value 1382, and a zero adjustment value 1392 (i.e., a value of zero). Zero/adjustment multiplexer 1391 selects zero adjustment value 1392 if decision signal 1390 signifies that a phase adjustment is not to be made. Alternatively, zero/adjustment multiplexer 1391 selects phase adjustment value 1382 if decision signal 1390 signifies that a phase adjustment is to be made. A zero/adjustment selection 1397 made by zero/adjustment multiplexer 1391 is output to add delta module 1370. If zero adjustment value 1392 is selected, add delta module 1370 adds a value of zero to the previous transmit clock signal phase 1384, resulting in a new transmit phase value 1386 equaling the previous transmit clock signal phase 1384. In effect, when this occurs, the transmit clock signal phase is not adjusted. If instead phase adjustment value 1382 is selected, add delta module 1370 adds or subtracts (depending on the specified direction) phase adjustment value 1382 to/from the previous transmit clock signal phase 1384, resulting in a new transmit phase value 1386. According to an embodiment of the invention, phase calculator 1262 includes all of the components and inputs of the embodiments described above with reference to FIGS. 13A and 13B. In this embodiment, decision signal 1390 signifies to zero/adjustment multiplexer 1391 whether to select phase adjustment value 1382 or zero adjustment value 1392 (i.e., a value of zero), based on phase limit signal 1389, phase threshold 1395, and transmit phase lock signal 1393. According to this embodiment, adjust decision module 1388 manages the phase limit signal 1389, phase threshold 1395, and transmit phase lock signal 1393 by utilizing the configuration of components shown in FIG. 14. FIG. 14 depicts an expanded view of adjust decision module 1388 in which adjust decision module 1388 includes a comparator 1402, an AND gate 1404, and an OR gate 1406, configured as shown. In this embodiment, comparator 1402 compares input phase threshold 1395 with input phase adjustment value 1382 to determine whether phase adjustment value 1382 exceeds phase threshold 1395. AND gate 1404 determines whether the threshold determination made by comparator 1402 is to be used as a factor in determining phase adjustment, depending on input phase limit signal 1389. Finally, OR gate 1406 determines whether the phase is to be locked at its current state regardless of the threshold-related determinations made by comparator 1402 and AND gate 1404. A method, according to an embodiment of the present invention, of synchronizing a receive clock signal phase of a receiving channel with a transmit clock signal phase of a transmitting channel in a transceiver is described in reference to FIG. 15. Method 1400 begins at step 1502. In step 1502, a previous receive clock signal phase of a receiving channel is stored for later comparison. In step 1504, a current receive clock signal phase of the receiving channel is identified. In step 1506, a phase difference between the previous receive clock signal phase and the current receive clock signal phase is determined. In step 1508, a direction of the phase difference between the previous clock signal phase and the current receive clock signal phase is identified. The direction may be identified as was described previously with reference to FIG. 8. In step 1510, a previous transmit clock signal phase of a transmitting channel is adjusted to a current transmit clock signal phase of the transmitting channel based on the phase difference and direction. Method 1500 then terminates. According to an embodiment of the present invention, steps 1502, 1504, 1506, and 1508 occur at the receiving channel, and step 1510 occurs at the transmitting channel. In another embodiment, step 1504 occurs at the receiving channel, and steps 1502, 1506, 1508, and 1510 occur at the transmitting channel. According to a further embodiment of the present invention, a method of synchronizing a receive clock signal phase of a receiving channel with a transmit clock signal phase of a transmitting channel in a transceiver is described in reference to FIG. 16. Method 1600 begins at step 1602. In step 1602, a previous receive clock signal phase of a receiving channel is stored for later comparison. In step 1604, a current receive clock signal phase of the receiving channel is identified. In step 1606, a phase difference between the previous receive clock signal phase and the current receive clock signal phase is determined. In step 1608, a direction of the phase difference between the previous clock signal phase and the current receive clock signal phase is identified. The direction may be identified as was described previously with reference to FIG. 8. In step 1610, the phase difference and direction is provided to a transmitting channel. In step 1612, a previous transmit clock signal phase of a transmitting channel is adjusted to a current transmit clock signal phase of the transmitting channel based on the phase difference and direction. Method 1600 then terminates at 1614. In this embodiment, steps 1602, 1604, 1606, 1608, and 1610 occur at the receiving channel, and step 1612 occurs at the transmitting channel. Step 1612 of method 1600 is further described in FIG. 17, according to an embodiment of the present invention. Step 1612 begins with step 1702. In step 1702, on a receive clock signal pulse, the phase difference and direction are received and written to a retiming module. In step 1704, on a transmit clock signal pulse, new transmit clock phase data is read out from the retiming module based on the phase difference and direction. Step 1612 then continues at step 1614, where the method terminates. According to yet another embodiment of the present invention, a method of synchronizing a receive clock signal phase of a receiving channel with a transmit clock signal phase of a transmitting channel in a transceiver is described in reference to FIG. 18. Method 1800 begins at step 1802. In step 1802, a previous receive clock signal phase of a receiving channel is stored. for later comparison. In step 1804, a current receive clock signal phase of the receiving channel is identified. In step 1806, the previous receive clock signal phase and the current receive clock signal phase is provided to a transmitting channel. In step 1808, a phase difference between the previous receive clock signal phase and the current receive clock signal phase is determined. In step 1810, a direction of the phase difference between the previous clock signal phase and the current receive clock signal phase is identified. The direction may be identified as was described previously with reference to FIG. 8. In step 1812, a previous transmit clock signal phase of the transmitting channel is adjusted to a current transmit clock signal phase of the transmitting channel based on the phase difference and direction. Method 1800 then terminates at 1814. In this embodiment, steps 1804 and 1806 occur at the receiving channel, and steps 1802, 1808, 1810, and 1812 occur at the transmitting channel. Step 1806 of method 1800 is further described in FIG. 19, according to an embodiment of the present invention. Step 1806 begins with step 1902. In step 1902, on receive clock signal pulses, the previous receive clock signal phase and the current receive clock signal phase are received and written to a retiming module of the transmitting channel. Step 1806 then continues at step 1808. According to an embodiment of the present invention, step 1812 of method 1800 is further described in FIG. 20. Step 1812 begins with step 2002. In step 2002, on a transmit clock signal pulse, new transmit clock phase data, based on the current receive clock signal phase and the previous receive clock signal phase, is read out from a retiming module of the transmitting channel. Step 1812 then continues at step 1814, where the method terminates. A method, according to an embodiment of the present invention, of phase-locking a transmit clock signal phase with a receive clock signal phase, is described in reference to FIG. 21. Method 2100 begins at step 2102. In step 2102, a predetermined phase difference and direction between a previous receive clock signal phase and a current receive clock signal phase is received. In step 2104, a current receive clock signal phase is received. In step 2106, the current receive clock signal phase is stored as a stored previous receive clock signal phase. In step 2108, a calculated phase difference and direction between the previous receive clock signal phase and the current receive clock signal phase is determined. In step 2110, a phase control selection signal is received. In step 2112, either the predetermined phase difference and direction or the calculated phase difference and direction is selected as the selected phase difference (and direction) to be used, depending on the phase control selection signal. In step 2114, a previous transmit clock signal phase is received. In step 2116, the selected phase difference is added or subtracted (depending on the specified selected direction) to the previous transmit clock signal phase to obtain an adjusted transmit clock signal phase. Method 2100 terminates at step 2118. A method, according to another embodiment of the present invention, of phase-locking a transmit clock signal phase with a receive clock signal phase, is described in reference to FIGS. 22A and 22B. Method 2200 begins at step 2202. In step 2202, a predetermined phase difference and direction between a previous receive clock signal phase and a current receive clock signal phase is received. In step 2204, a current receive clock signal phase is received. In step 2206, the current receive clock signal phase is stored as a stored previous receive clock signal phase. In step 2208, a calculated phase difference and direction between the previous receive clock signal phase and the current receive clock signal phase is determined. In step 2210, a phase control selection signal is received. In step 2212, either the predetermined phase difference and direction or the calculated phase difference and direction is selected as the selected phase difference and direction to be used, depending on the phase control selection signal. In step 2214, a transmit phase lock signal is received. If the transmit phase lock signal is set, signifying that no adjustment is to be made, then the method continues at step 2216. In step 2216, the selected phase difference is changed to a value of zero. In step 2218, a previous transmit clock signal phase is received. In step 2220, the selected phase difference is added to or subtracted from (depending on the specified direction) the previous transmit clock signal phase to obtain an adjusted transmit clock signal phase. In this scenario, the transmit clock signal phase remains unchanged (i.e., no phase adjustment). Method 2200 terminates at step 2222. If, instead, the transmit phase lock signal is not set in step 2214, signifying that an adjustment may be made, the method continues at step 2218 in one embodiment, or alternatively at step 2224 (FIG. 22B) in another embodiment, if the phase adjustment is optionally to be limited to a phase threshold. In the embodiment with no phase threshold option, step 2214 proceeds to step 2218. In step 2218, a previous transmit clock signal phase is received. In step 2220, the selected phase difference is added to or subtracted from (depending on the specified direction) the previous transmit clock signal phase to obtain an adjusted transmit clock signal phase. Method 2200 terminates at step 2222. In the embodiment involving the phase threshold option, if the transmit phase lock signal is not set in step 2214, the method continues at step 2224. In step 2224, a phase limit signal is received. The phase limit signal signifies whether to limit phase adjustment of the previous transmit clock signal phase regardless of whether the selected phase difference is outside a predetermined phase threshold. If the phase limit signal signifies that phase adjustment is not to be limited, the method proceeds to step 2218. If the phase limit signal signifies that phase adjustment is to be limited, the method proceeds to step 2226. In step 2226, a predetermined phase threshold is received. In step 2228, it is determined whether the selected phase difference is outside the predetermined phase threshold. If the selected phase difference is outside the predetermined phase threshold, then the method continues at step 2216 in which the selected phase difference is changed to a value of zero (i.e., no phase adjustment is to be made). If the selected phase difference is within the predetermined phase threshold, then the method continues at step 2218. In step 2218, a previous transmit clock signal phase is received. In step 2220, the selected phase difference is added to or subtracted from (depending on the specified direction) the previous transmit clock signal phase to obtain an adjusted transmit clock signal phase. Method 2200 terminates at step 2222. A method of transferring data from a first external component coupled to a receive channel of a transceiver system to a second external component coupled to a transmit channel of the transceiver system, according to another embodiment of the present invention, is described in reference to FIG. 23. The external components include, but are not limited to, disk drives. Method 2300 begins at step 2302. In step 2302, external component data from a first external component is received at a receive channel. In step 2304, the external component data and receive clock phase data is transferred from the receive channel to a transmit channel. In step 2306, a transmit clock signal is phase-locked with a receive clock signal per the receive clock phase data. In step 2308, the external component data is transmitted from the transmit channel to a second external component. Method 2300 then terminates. The systems and methods described above include essentially two phase difference calculation options. In the first option, a phase difference and direction are calculated at a receive channel and transferred to a transmit channel for the adjustment of the transmit clock phase. In the second option, the calculation of the phase difference and direction is made at the transmit channel. Both options are preferably programmed in the system so that either can be selected. One advantage of using the first option is that fewer bits are transferred. One advantage of using the second option is that if the receive channel and transmit channel are located far away from each other, it is safer to do the calculation locally at the transmit channel. If the first option is used in this situation, the phase difference may have changed again by the time it reaches the transmit channel, placing data integrity at risk. Conclusion This disclosure presents a transceiver system with a transmit clock signal phase phase-locked with a receive clock signal phase. This disclosure also presents a method of transferring data from a first external component to a second external component using a transceiver system such as disclosed herein. By slaving the phases through an appropriate mechanism such as the present invention, a robust design results in which a transmit frequency of the device can track a receive frequency with no loss of data/information. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the invention as defined in the appended claims. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention relates generally to transceiver devices. More particularly, this invention relates to serializer/deserializer (SERDES) components of a transceiver device, and the phase-locking of a transmit clock signal phase with a receive clock signal phase. 2. Related Art A serializer/deserializer (SERDES) device converts received high-speed serial data into low-speed parallel data at a receiver. The parallel data may then be processed and then passed to a transmitter. At the transmitter, the low-speed parallel data is converted back into high-speed serial data for transmission out of the SERDES device. A SERDES device is used to control external devices, or used as a repeater, allowing data from one external device, such as a disk drive, to be transferred to another external device. For example, the external devices may be disk drives that include identical data, providing a back-up mechanism in the event that one disk drive fails. As another example, the external devices may be individual disk drives that, as a group, form one or more databases. A SERDES device may include a plurality of SERDES cores. Each SERDES core may include one or more receiver/transmitter pairs. Multiple SERDES cores may be daisy-chained together such that data received by one core may be transmitted by another core. Communication between a receiver and a transmitter of a SERDES device involves high-speed clocks. A typical mode of operation in a SERDES device is a repeat mode in which the transmit data frequency needs to track the receiver data frequency in order to preserve data integrity. This operation must be performed at the receiver without having to retime the recovered clock to the local clock. For high-speed communication, one typically needs to have very well-matched clocks, especially if transferring data between SERDES cores on different substrates (e.g., chips) or boards. For example, if transferring data from a receiver on one SERDES core to a transmitter on another SERDES core, the clocks between the receiver and the transmitter should be matched in order to sample the data at the right time. If the clocks are not matched, the frequency difference between the two clocks will drift over time, resulting in what appears to be an extra pulse or a missing pulse. This frequency drift will eventually cause a loss of data integrity. One solution is to use a common clock at the receiver and the transmitter. However, on today's large and complicated systems, it is not practical to run high-frequency lines between every receiver and transmitter. Furthermore, although electronic components are very small, there is a relatively large distance between them. It may not be feasible to maintain a common clock over such a distance. For similar reasons, it may not be feasible to maintain direct clock-matching over such a distance. SERDES devices that work at much slower speeds and do not link many devices together may not have a frequency drift issue. For example, SERDES devices that work at about 2.5 Gigahertz may not have a frequency drift issue. However, more modern SERDES devices work at 4 Gigahertz or more. In a transceiver, there is typically a digital portion and an analog portion. When synchronizing a transmitter clock to a receiver clock, and jumping from one frequency to another frequency, instability of the system and loss of data integrity may occur on the analog side. Furthermore, if the frequency change is too large, the new clock pulse width may be larger than the minimum clock pulse width required on the digital side. It is important to prevent large frequency changes such as that just described in order to preserve data integrity and prevent system errors. What is needed is a high-speed SERDES transceiver device in which a transmitter clock signal is synchronized with a receiver clock signal without the frequency drift problems described above. Furthermore, what is needed is the capability to synchronize a transmitter clock signal with a receiver clock signal of a receiving component that is part of a different SERDES core, a different substrate, or even a different board, without the frequency drift problems such as those described above. What is also needed is a mechanism to prevent transmitter clock frequency changes that are so large as to violate a minimum pulse width required by a receiver. | <SOH> SUMMARY OF THE INVENTION <EOH>A transceiver system is disclosed that includes a plurality of transceiver chips. Each transceiver chip includes one or more SERDES cores. Each SERDES core includes one or more SERDES lanes. Each SERDES lane includes a receive channel and a transmit channel. The transmit channel of each SERDES lane is phase-locked with a corresponding receive channel. According to an embodiment of the present invention, each SERDES core receives and transmits data to and from external components connected to the SERDES core. In an embodiment, the external components include disk drives, such as hard disk drives, or removable media drives (e.g., a compact disc drive). The external components may also include databases or other media formats that contain, manipulate, or transfer data. According to an embodiment of the present invention, the transmit channel and the corresponding receive channel are each part of a common SERDES lane. In another embodiment, the transmit channel is part of a first SERDES lane of a common SERDES core, and the corresponding receive channel is part of a second SERDES lane of the common SERDES core. In a further embodiment, the transmit channel is part of a first SERDES core, and the corresponding receive channel is part of a second SERDES core. According to an embodiment of the present invention, the first SERDES core and the second SERDES core are disposed on a common substrate. In another embodiment, the first SERDES core is disposed on a first substrate and the second SERDES core is disposed on a second substrate. In one embodiment, the first substrate and the second substrate are disposed on a common board. In another embodiment, the first substrate is disposed on a first board, and the second substrate is disposed on a second board. A method of transferring data from a first external component coupled to an active receive channel of a transceiver system to a second external component coupled to an active transmit channel of the transceiver system is also disclosed. The transceiver system is that of the various embodiments described above. The external components include, but are not limited to, disk drives. The method includes receiving external component data from the first external component, transferring the external component data and receive clock phase data from the active receive channel to the active transmit channel, phase-locking the transmit clock signal with the receive clock signal per the receive clock phase data, and transmitting the external component data to the second external component. According to an embodiment of the present invention, the receiving step receives the external component data in analog format, the transferring step transfers the external component data and receive clock signal phase data in digital format, and the transmitting step transmits the external component data in analog format. According to another embodiment of the present invention, the receiving step receives the external component data in series, the transferring step transfers the external component data and receive clock signal phase data in parallel, and the transmitting step transmits the external component data in series. | 20040331 | 20090922 | 20050804 | 60240.0 | 0 | BOCURE, TESFALDET | TRANSCEIVER SYSTEM AND METHOD HAVING A TRANSMIT CLOCK SIGNAL PHASE THAT IS PHASE-LOCKED WITH A RECEIVE CLOCK SIGNAL PHASE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,466 | ACCEPTED | Device and method for health monitoring of an area of a structural element, and structure adapted for health monitoring of an area of a structural element of said structure | Device for health monitoring of a structure comprising a dielectric material of permittivity εr, comprising a source of electromagnetic radiation, generating an electric field in the structure a detector measuring a component of the electric field, calculation means giving the value of εr on the basis of the said component. | 1. Device for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity εr comprising: (A) means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (B) detection means suitable for measuring a first measured component of an electric field, along a first direction of detection, characterized in that the said device furthermore comprises calculation means (C) suitable for obtaining a value of the dielectric permittivity εr in the said area on the basis of the said first measured component. 2. Device according to claim 1, in which the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, in which the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and in which the calculation means (C) are alternatively or furthermore suitable for obtaining a value of the electrical conductivity a in the said area on the basis of the said first measured component. 3. Device according to claim 2, in which the said detection means are suitable for furthermore measuring a second measured component of the said electric field, along a second direction of detection forming with the said first direction of detection a nonzero angle, and in which, the calculation means are suitable for obtaining a value of the electrical conductivity σ and of the electrical permittivity εr in the said area on the basis of the said first and the said second measured components. 4. Device according to claim 3, in which a direction chosen from the first and the second direction of detection is the said direction of means of emission. 5. Device according to claim 2, in which the said means of emission comprise a layer comprising, at said area, at least two parallel conducting tracks, oriented along the said dipole direction and suitable for being able to be traversed in mutually opposite senses by an electric current. 6. Device according to claim 3, in which the said detection means comprise a layer comprising, at said area, at least one conducting track oriented along the said first direction of detection, and a layer comprising, at said area, at least one conducting track oriented along the said second direction of detection. 7. Device according to claim 2, in which the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission, along the said first direction of detection, and (F) comparison means suitable for comparing the said simulated component and the said corresponding measured component obtained by the means of detection (B). 8. Device according to claim 3, in which the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a first and a second simulated component of the said simulated electric field along the said first and second directions of detection, and (F) comparison means suitable for comparing the said simulated components and the said corresponding measured components obtained by the detection means (B). 9. Device according to claim 7 furthermore comprising (D) generating means suitable for generating the said model contained in the memory means (Z). 10. Device according to claim 2, furthermore comprising (G) a database containing data relating to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity εr for the said materials. 11. Device according to claim 2, furthermore comprising a layer for integrated monitoring of the structures based on piezoelectric technology. 12. Device according to claim 1 in which the said structural element comprises no imperfectly conducting material, and in which the means of emission are means of emission of electrical radiation that are suitable for generating an electric field extending in the said direction. 13. Structure suitable for health monitoring of an area of a structural element of the said structure, and comprising: the said structural element comprising at least one dielectric material of dielectric permittivity εr, an electromagnetic radiation emission layer extending in a direction, the said electromagnetic field generating an electric field in the area, a detection layer suitable for measuring a first measured component of an electric field, along a first direction of detection, and at least one facility for connection to calculation means suitable for obtaining a value of the dielectric permittivity εr in the said area on the basis of the said first measured component. 14. Structure according to claim 13 in which the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, in which the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and in which the calculation means (C) are alternatively or furthermore suitable for obtaining a value of the electrical conductivity C in the said area on the basis of the said first measured component. 15. Structure according to claim 13, the said structural element taking the form of at least one layer, the said detection layer being disposed between the said structural element layer and the said emission layer. 16. Structure according to claim 13, the said structural element taking the form of at least one layer, the said emission layer being disposed between the said structural element layer and the said detection layer. 17. Structure according to claim 13, the said structural element taking the form of at least one layer, the said structural element layer being disposed between the said emission layer and the said detection layer. 18. Structure according to claim 14, the said inhomogeneous structural element taking the form of at least one fine layer comprising at least one imperfectly conducting material in the form of at least one carbon fibre, of electrical conductivity σ, and one dielectric material in the form of a matrix of dielectric permittivity εr, in which the said carbon fibres are embedded. 19. Method for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity εr, comprising the steps during which: (a) an electromagnetic field is generated, by means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (b) a first measured component of an electric field is measured, along a first direction of detection, characterized in that the method furthermore comprises a step (c) during which a value of the dielectric permittivity εr in the said area is obtained on the basis of the said first measured component. 20. Method according to claim 19, in which the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, in which, during step (a), a magnetic field is generated by means of emission of magnetic radiation, the said magnetic field being, at the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and in which during step (c), a value of the electrical conductivity a in the said area is alternatively or furthermore obtained on the basis of the said first measured component. 21. Method according to claim 19, in which, during a first iteration, steps (a) to (c) are performed for a first frequency of the emission means, during a second iteration, steps (a), (b) and (c) are repeated for a second frequency, and during step (c) of the second iteration, the value obtained during step (c) of a previous iteration is taken into account. 22. Method according to claim 20, in which, during each step (b), a second measured component of the said electric field is furthermore measured, along a second direction of detection forming with the said first direction a nonzero angle, and in which, during step (c) of each iteration, the said first and second measured components are taken into account. 23. Method according to claim 20, in which, during step (c), for each iteration, furnished, in memory means, with an initial model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said emission means, (e) at least one first simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission is estimated, along a direction of detection chosen from the said first and second direction of detection, and (f) the said simulated component and the said corresponding measured component obtained during step (b) are compared. 24. Method according to claim 23, furthermore comprising, prior to step (e), a step (d) in which an initial model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, are generated in the memory means. 25. Method according to claim 23, in which, during step (b), a second measured component of the said electric field is measured, along the other direction of detection, in which, during step (e), a second corresponding simulated component of the said simulated electric field is estimated, and in which, during step (f), the said second simulated component and the said second measured component obtained during step (b) are compared. 26. Method according to claim 23, in which, subsequent to step (f), step (d′) is furthermore implemented, in which a modified model of the area is generated by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, differing from the initial model through at least one of the numerical parameters, and steps (e) and (f) are implemented for the said modified model. 27. Method according to claim 23, in which step (c) furthermore comprises a step (g) during which at least one characteristic of the area chosen from the conductivity σ and the permittivity εr is determined by identifying the said simulated conductivity σs with the said conductivity and/or the said simulated permittivity εsr with the said permittivity, as soon as the comparison performed in step (f) gives a satisfactory result. 28. Method according to claim 20, furthermore comprising a step during which (h) an energy absorbed by the said structural element exhibiting the said electrical conductivity σ and/or the said dielectric permittivity εr that are obtained in step (c) is determined by inference on a database containing data pertaining to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity εr for the said materials. 29. Method according to claim 20 in which the said structural element comprises no, even imperfectly, electrically conducting material, in which, during step (a), an electric field is generated in the area, in the said direction, with the aid of means of emission of electrical radiation. 30. Method according to claim 29, in which, during step (c), furnished, in memory means (3), with an initial model of the area by at least one numerical parameter related to εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (d) a simulated component of a simulated electric field induced in the said model of the area by the said model of means of emission is estimated, and (e) the said simulated component and the said corresponding measured component obtained during step (b) are compared. | FIELD OF THE INVENTION The present invention relates to devices and methods for health monitoring of an area of a structural element, and to a structure adapted for health monitoring of an area of a structural element of this structure. TECHNOLOGICAL BACKGROUND More particularly, the invention concerns a device for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity εr comprising: (A) means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (B) detection means suitable for measuring a first measured component of an electric field, along a first direction of detection. The structural elements in question are typically materials made of resin reinforced with glass fibres or carbon fibres, forming part of the structure, for example of a vehicle such as a motor vehicle, an aircraft, a railway vehicle, or the like, for which the weight constraints are paramount. Such a device has already been used with success in the past to determine whether such a structural element exhibited a defect, for example of a mechanical or chemical nature, or the like. Such an example of an application is described in “Electromagnetic health monitoring system for composite materials”, Lemistre and Balageas, in Matériaux et Techniques, special issue 2002, published by SIRPE, Paris, pg 29-32. In this article, the electromagnetic field is, for structures comprising carbon fibres, a magnetic field locally equivalent to the magnetic field emitted by a dipole extending along a given direction of the structural element and is emitted by two linear conducting tracks extending in this direction and traversed in opposite senses by an electric current. The electric field is measured orthogonally to this direction in the plane of the structure. The information thus gleaned is useful for determining whether the structure does or does not exhibit a defect. For structures comprising glass fibres or simply a resin, the exciter field is an electromagnetic field emitted by the tracks extending likewise in this direction. Such a device makes it possible to qualify the presence or otherwise of a structural defect in the structure under study, but does not make it possible to determine the gravity of the defect. In the presence of a defect, the user of the device will not know what to do: wait or replace the structure (thereby guaranteeing safety to the detriment of cost) even if the defect is not perhaps penalizing per se for the structure in its daily application. SUMMARY Thus, according to the invention, a device of the kind in question is essentially characterized in that the said device furthermore comprises calculation means suitable for obtaining a value of the dielectric permittivity εr in the said area on the basis of the said first measured component. By virtue of these arrangements, information pertaining to the structural element is obtained, making it possible to quantify the gravity of the defect exhibited by the structural element, since an intrinsic characteristic of the material is determined. In practice, this makes it possible to forecast the type of intervention to be undertaken with regard to the structural element, to eliminate the defect, rather than to have to replace the entire structural element through ignorance. In preferred embodiments of the invention, recourse may possibly be had moreover to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and the calculation means are alternatively or furthermore suitable for obtaining a value of the electrical conductivity σ in the said area on the basis of the said first measured component; the said detection means are suitable for furthermore measuring a second measured component of the said electric field, along a second direction of detection forming with the said first direction of detection a nonzero angle, and the calculation means are suitable for obtaining a value of the electrical conductivity σ and of the electrical permittivity εr in the said area on the basis of the said first and the said second measured components; a direction chosen from the first and the second direction of detection is the said direction of means of emission; the said means of emission comprise a layer comprising, at said area, at least two parallel conducting tracks, oriented along the said dipole direction and suitable for being able to be traversed in mutually opposite senses by an electric current; the said detection means comprise a layer comprising, at said area, at least one conducting track oriented along the said first direction of detection, and a layer comprising, at said area, at least one conducting track oriented along the said second direction of detection; the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission, along the said first direction of detection, and (F) comparison means suitable for comparing the said simulated component and the said corresponding measured component obtained by the means of detection (B); the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a first and a second simulated component of the said simulated electric field along the said first and second directions of detection, and (F) comparison means suitable for comparing the said simulated components and the said corresponding measured components obtained by the detection means (B); the device furthermore comprises (D) generating means suitable for generating the said model contained in the memory means (Z); the device furthermore comprises (G) a database containing data relating to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity εr for the said materials; the device furthermore comprises a layer for integrated monitoring of the structures based on piezoelectric technology; the said structural element comprises no imperfectly conducting material, and the means of emission are means of emission of electrical radiation that are suitable for generating an electric field extending in the said direction. According to another aspect, the invention relates to a structure suitable for health monitoring of an area of a structural element of the said structure, and comprising: the said structural element comprising at least one dielectric material of dielectric permittivity εr, an electromagnetic radiation emission layer extending in a direction, the said electromagnetic field generating an electric field in the area, a detection layer suitable for measuring a first measured component of an electric field, along a first direction of detection, and at least one facility for connection to calculation means suitable for obtaining a value of the dielectric permittivity εr in the said area on the basis of the said first measured component. According to embodiments, recourse may also be had to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, in which the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the level of the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and in which the calculation means are alternatively or furthermore suitable for obtaining a value of the electrical conductivity σ in the said area on the basis of the said first measured component; the said structural element takes the form of at least one layer, the said detection layer being disposed between the said structural element layer and the said emission layer; the said structural element takes the form of at least one layer, the said emission layer being disposed between the said structural element layer and the said detection layer; the said structural element takes the form of at least one layer, the said structural element layer being disposed between the said emission layer and the said detection layer; the said inhomogeneous structural element takes the form of at least one fine layer comprising at least one imperfectly conducting material in the form of at least one carbon fibre, of electrical conductivity σ, and one dielectric material in the form of a matrix of dielectric permittivity εr, in which the said carbon fibres are embedded. According to another aspect, the invention relates to a method for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity εr, comprising the steps during which: (a) an electromagnetic field is generated, by means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (b) a first measured component of an electric field is measured, along a first direction of detection, characterized in that the method furthermore comprises a step (c) during which a value of the dielectric permittivity εr in the said area is obtained on the basis of the said first measured component. According to preferred embodiments, recourse may moreover be had to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, during step (a), a magnetic field is generated by means of emission of magnetic radiation, the said magnetic field being, at the level of the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and during step (c), a value of the electrical conductivity σ in the said area is alternatively or furthermore obtained on the basis of the said first measured component; during a first iteration, steps (a) to (c) are performed for a first frequency of the emission means, during a second iteration, steps (a), (b) and (c) are repeated for a second frequency, and during step (c) of the second iteration, the value obtained during step (c) of a previous iteration is taken into account; during each step (b), a second measured component of the said electric field is furthermore measured, along a second direction of detection forming with the said first direction a nonzero angle, and during step (c) of each iteration, the said first and second measured components are taken into account; during step (c), for each iteration, furnished, in memory means, with an initial model of the area through at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said emission means, (e) at least one first simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission is estimated, along a direction of detection chosen from the said first and second direction of detection, and (f) the said simulated component and the said corresponding measured component obtained during step (b) are compared; the method furthermore comprises, prior to step (e), a step (d) in which an initial model of the area by at least two numerical parameters related to σs representing the said electrical conductivity a in this area, and εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, are generated in the memory means; during step (b), a second measured component of the said electric field is measured, along the other direction of detection, during step (e), a second corresponding simulated component of the said simulated electric field is estimated, and during step (f), the said second simulated component and the said second measured component obtained during step (b) are compared; subsequent to step (f), step (d′) is furthermore implemented, in which a modified model of the area is generated by at least two numerical parameters related to σs representing the said electrical conductivity σ in this area, and εrs representing the said dielectric permittivity in this area, differing from the initial model through at least one of the numerical parameters, and steps (e) and (f) are implemented for the said modified model; step (c) furthermore comprises a step (g) during which at least one characteristic of the area chosen from the conductivity σ and the permittivity εr is determined by identifying the said simulated conductivity σs with the said conductivity and/or the said simulated permittivity εsr with the said permittivity, as soon as the comparison performed in step (f) gives a satisfactory result; the method furthermore comprises a step during which (h) an energy absorbed by the said structural element exhibiting the said electrical conductivity σ and/or the said dielectric permittivity εr that are obtained in step (c) is determined by inference on a database containing data pertaining to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity εr for the said materials; the said structural element comprises no, even imperfectly, electrically conducting material, and, during step (a), an electric field is generated in the area, in the said direction, with the aid of means of emission of electrical radiation; during step (c), furnished, in memory means, with an initial model of the area by at least one numerical parameter related to εrs representing the said dielectric permittivity in this area, and a model of the said means of emission, (d) a simulated component of a simulated electric field induced in the said model of the area by the said model of means of emission is estimated, and (e) the said simulated component and the said corresponding measured component obtained during step (b) are compared. DESCRIPTION OF THE FIGURES Other characteristics and advantages of the invention will become apparent during the following description of one of its embodiments, given by way of nonlimiting example, with regard to the appended drawings. In the drawings: FIG. 1 is a perspective view of an instrumented structure, FIG. 2 is a perspective view of the internal face of an area of the structure presented in FIG. 1 furnished with a device according to the invention, FIG. 3 is an exploded perspective view of a composite structure to which the invention is applicable, FIG. 4 is a plane diagrammatic view of a source of magnetic radiation used within the invention, FIGS. 5a, 5b, 5c are plane diagrammatic views of various embodiments or of means of detection according to the invention, FIGS. 6a, 6b, 6c are diagrammatic views of the model used within the invention, FIG. 7 is a diagrammatic side view representing the calculation of the electric field in a medium, within the invention, FIG. 8 is a diagrammatic figure representing the calculation of the effective sources in a structure, FIG. 9 is a diagrammatic side view representing the calculation of the electric field in a medium 1 within the framework of the invention, FIGS. 10a and 10b represent an alternative to the electric field calculation at the level of the internal face 1b of the structure, FIG. 11 is a plane diagrammatic view of a model of damage of the structure under study, FIG. 12 is a schematic representative of the calculation of σ and/or εr for the structure under test, FIG. 13 is a diagrammatic side view representative of the calculation corresponding to a multilayer structure, and FIG. 14 is a perspective view representing another type of structure, of the sandwich kind, that may be furnished with a device according to a second embodiment of the invention. In the various figures, the same references designate identical or similar elements. DESCRIPTION OF THE EMBODIMENTS FIG. 1 represents a structural element 1 which is typically a part of a structure embodied from a composite material of the type comprising a resin reinforced with carbon fibres. The structural element in question is, for example, a stiff element of the structure of a space, naval, automobile, railway or other vehicle, in which the composite materials find important applications, in particular by virtue of the saving in weight that they allow the structure to exhibit with respect to a metal structure exhibiting equivalent stiffness. Thus, the structural element 1 in question may be an entity undergoing manufacture, or otherwise, intended to be mounted in a complete structure, or may possibly be part of a complete structure in service. The structural element 1 comprises a structure integrated monitoring device 2 (see the following figures) which is, for example, disposed on its internal face 1b, the external face 1a of the structural element being turned towards the outside space, and therefore, liable to be damaged during use of the vehicle comprising the structural element. The monitoring device 2 is thus used to evaluate the magnitude of the damage suffered by the structural element at its external face 1a. Such damage may be caused either in the normal use of the vehicle comprising the structural element, or deliberately during manufacture, during tests intended to study the resistance of the structural element intended to form part of the structure, or to verify the properties of the materials used during of the manufacture of the structural element. This damage is typically of three distinct types, namely: damage of a mechanical origin, as a result for example of an impact, or damage of a thermal origin, as a result of a considerable rise in temperature suffered by the item, or of a chemical nature, following for example the absorption of a liquid. The integrated monitoring device 2 has connection facilities suitable for linking it to a control unit 3 used to emit excitation signals towards the monitoring device, and to receive signals from this monitoring device, these signals being dependent on the possible damage to the structural element. Reference is now made to FIG. 2 which represents in a diagrammatic manner an area of the structural element 1, furnished on its internal face 1b with the structure integrated monitoring device 2, according to an embodiment of the latter. The device as such takes the form of conducting tracks held in a mylar and fixed for example by gluing to the internal face 1b of the structural element. The device 2 comprises in particular an emission layer 4 (detailed later) comprising a plurality of parallel linear conducting tracks 9 extending along an axis X of the structural element, and linked together, for example at one end, by a conducting track 10, for example perpendicular. The device for integrated monitoring of structures also exhibits means of detection in the form of a detection layer 5, also comprising conducting tracks 12, and possibly taking the form of a plurality of variants as described in relation to FIGS. 5a, 5b and 5c. The emission layer 4 can be disposed between the structural element 1 and the detection layer 5 or, instead, it is the detection layer 5 which is disposed between the emission layer 4 and the structural element 1. The tracks of the emission layer 4 and of the detection layer 5 are linked to the central unit 3. FIG. 2 represents a small enough portion of the structural element of FIG. 1 as to be locally regarded as planar in the plane (X; Y). The flexibility of the emission layer 4 and detection layer 5 allows them to be fixed, for example by gluing onto the internal face of the entire structural element 1, even if the latter exhibits a nonzero curvature, as represented in FIG. 1. FIG. 3 represents for example the structural element 1 in the form of a composite element consisting of a matrix 6, a dielectric material characterizable by its dielectric permittivity εr, and of carbon fibres 7, or of any other suitable imperfectly electrically conducting material, characterizable by its electrical conductivity σ. In a conventional manner, the composite structural element 1 comprises several layers 8a, 8b, 8c, 8d in which the carbon fibres extend in different directions so as to give the structure an orthotropic character. The layers 8a and 8d thus exhibit carbon fibres extending in the direction X, while layers 8b and 8c exhibit carbon fibres extending in the direction Y. The invention can also be used for quasi-isotropic structures in which the carbon fibres of successive layers form an angle of 45° between themselves, or any appropriate composite material based on imperfectly conducting material. FIG. 4 diagrammatically represents the emission layer 4 fixed on the structural element 1 and comprising parallel electrically linear conducting tracks 9 extending in the direction X and linked together for example at one end by an electrically conducting track 10 possibly exhibiting a series of switches 11, and linked at their other end to the control unit 3. The control unit 3 can emit a current i into a conducting track 9a, the switch 11 associated with this conducting track 9a being closed, and the other switches 11 being open, so that the current also flows in the neighbouring conducting track 9b in the opposite sense from the current flowing in the conducting track 9a, in such a way as to form a loop generating in the structure a magnetic field B equivalent to the magnetic field generated by a magnetic dipole oriented along the X direction. The current i emitted by the central unit 3 is preferably an alternating current generated successively at several frequencies as described in greater detail in what follows. The current in question is emitted successively into the various tracks 9 of the emission layer 4, and the corresponding switches may be open or closed in a manner suitable for being able to scan the structure 1 along the Y direction. Any other suitable means for scanning the structure may be used. All these operations are controlled by the central unit 3. In a conventional manner, for hybrid integrated monitoring of structures, the magnetic field B emitted by the emission layer 4 generates in the imperfectly conducting structural element 1 eddy currents that form an electric field E detected by the detection layer 5. FIG. 5a represents, for example, in a likewise diagrammatic manner, a first embodiment of such a detection layer 5 according to the invention. In this first embodiment, it is more judicious to speak of two detection layers 5a, 5b, intended to be placed one on the other, the layer 5b comprising a series of linear parallel conducting tracks 12 linked at one end to the central unit 3, and free at the other end, and disposed along the Y axis perpendicularly to the conducting tracks 9 of the emission layer 4. A detection layer 5b of this kind has already been described repeatedly, and in particular in the abovementioned article, and is suitable for detecting the component Ey extending along the Y direction of the electric field E. The layer 5a is composed in a similar manner and exhibits conducting tracks 12 likewise linked to the control unit 3, but oriented along the X direction so as to detect the component Ex of the electric field E. Let us also note here that the components Ex and Ey detected are defined by the orientation of the equivalent magnetic dipole at the level of the emission layer in the area under study, and that the orientation of the carbon fibres in the material is in this respect irrelevant. The information measured by exciting the conducting fibres 9a and 9b of the emission layer 4 and the conducting tracks 12a and 12b of the detection layer 5 makes it possible to obtain information relating to Ex and/or Ey at the level of the “intersection” of these tracks. By exciting the various conducting tracks 9a, 9b in succession, then for each, by exciting the various conducting tracks 12a and 12b in succession, a complete mapping of the structural element 1 bearing the device for integrated monitoring of structures 2, even of large size, is thus obtained in a fraction of a second. For each point scanned, the current emitted is an alternating current emitted successively at various frequencies, this making it possible to also scan the structure 1 depthwise. By scanning the structure at a high frequency, corresponding to the thickness of the surface layer of the structural element, information specific to this layer is obtained. By lowering the frequency to a frequency corresponding to the thickness of the first two layers, information relating to these two layers is obtained. By using the information obtained for the first layer, information about the second layer alone is obtained. By continuing thus, the structural element is scanned depthwise. In practice, the damage suffered by the structure will have been suffered on its external face 1a, and the integrated monitoring device 2 will be disposed on its internal face 1b, in particular in such a way as to prevent any risk of damage of the integrated monitoring device, and it is therefore essential that the latter be capable of determining damage occurring “depthwise” with respect to itself. Hence, the iterative calculations can be performed layer by layer beginning with a low frequency to obtain information about the entire structure, then raising the frequency successively. The inventors have noted that the detection of the component Ey of the electric field traversing the structural element 1 made it possible to obtain additional information with respect to the sole detection of the component Ex of the electric field. With the aid of the two independent components Ex and Ey it is possible by calculation to retrieve a value of the two characteristics of the material, namely the electrical conductivity σ of the medium and the dielectric permittivity εr of the matrix. The measured components may be real or complex of the form Ex=E0x ej(ωt+φ), thus carrying the amplitude information and phase information. The separate calculation of the electrical conductivity σ and of the dielectric permittivity εr is beneficial, since in its turn it makes it possible to characterize the type of defect that the structure may have suffered, between on the one hand the defects of a mechanical origin which give rise to delamination between layers and possibly rupture of the carbon fibres and thus solely a variation in the electrical conductivity σ, or on the other hand, the defects of a chemical or thermal origin that give rise to damage chiefly of the matrix and therefore a modification of the dielectric permittivity εr of the latter, and possibly of the conductivity σ of the medium by pyrolysis of the resin. The benefit of being able to characterize the nature of the damage that the structure has suffered is of being able to forecast for example the type of intervention (repair) to be conducted on the structure. The inventors have, furthermore, shown that this method made it possible to detect defects of a chemical and/or thermal origin with greater accuracy than the existing techniques for integrated monitoring of structures, which are more suited for measuring defects of a mechanical origin. Of course, there are numerous other means, within the invention, for detecting the component Ey of the electric field traversing the structure. In particular, two alternative embodiments of the detection layer are presented with reference to FIGS. 5b and 5c respectively. In FIG. 5b, the detection layer 5 is now formed only by a single layer which comprises a series of zigzag conducting tracks 12, the tracks 12a and 12b remaining parallel while forming these zigzags. In a purely illustrative manner, also represented in FIG. 5b are the conducting tracks 9a and 9b of the emission layer 4, said tracks being superposed on the detection layer 5 and excited by the central unit 3, and traversed by the current i. The central unit 3 may then read at the level of the conducting tracks 12a and 12b information relating to Ex+Ey if the zigzags are oriented by 45° with respect to the X and Y direction. This embodiment is the embodiment illustrated in FIG. 2 globally representing the structure and likewise the emission layer 4. According to a third embodiment represented in FIG. 5c, the embodiment of FIG. 5b is again employed for the detection layer 5 and it is supplemented with a series of pairwise parallel conducting tracks 12c, 12d, superposed respectively on the conducting track 12a and on the conducting track 12b according to an inverse zigzag, so that while the conducting tracks 12a and 12b make it possible to obtain information relating to Ex+Ey, the parallel conducting tracks 12c and 12d make it possible to obtain for the same excited conducting tracks 9a, 9b of the emission layer 4 information relating to the component Ex−Ey of the electric field. By combining these items of information, the components Ex and Ey will be retrieved directly, separately. It is of course not obligatory for the zigzags formed by the conducting tracks 12a, 12b, 12c, 12d in any of the embodiments presented, to form an angle of 45° with the X and Y directions such as defined by the orientation of the conducting tracks 9 of the emission layer 4, and it is possible to choose any angle whatsoever. Furthermore, although the zigzags of the conducting tracks 12a to 12d are represented at right angles, it is permissible for the conducting tracks in question to exhibit rounded angles for reasons of practical implementation. The signal detected at the level of the conducting tracks 12 of the detection layer by the central unit 3 is possibly processed by well-known signal processing algorithms such as already used in the field of the integrated monitoring of structures, such as for example the Donoho algorithm cited in the abovementioned article. Such signal processing may, in fact, be useful for circumventing the various noise terms carried by the signal. The device as described makes it possible to obtain quantitative results regarding the state of health of structures, for example by comparing the results obtained with results obtained previously for the structure in question, for example when bringing the structure into service, or during an earlier examination if the structure is scanned periodically. The comparing of the detection results with previous detection results makes it possible to determine the occurrence and the nature of any damage suffered by the structure. It is, moreover, possible to quantify the level of damage, as described subsequently with the aid of a model suitable for calculating the electric field for the structure under study, at the level of the detection layer. In order to do this, use is made, in the central unit 3, of a model of the structure, which may for example have been previously devised at the time the structure was brought into service. This model is in particular suitable for the application thereto of the DPSM method (the acronym standing for the expression Distributed Point Source Method) which will be detailed in a general manner with the aid of FIGS. 6a, 6b, and 6c. This method is particularly suitable in that it makes it possible to obtain information relating to a point (or a limited part) of space in short computation times. This said, there is nothing preventing the device described above from being used with a classical method of computation of the “finite elements” kind. Reference is firstly made to FIG. 6a, in which a first surface b is meshed according to a plurality of surface samples such as dS′1, dS′2, dS′3 and dS′4. Likewise a second surface a is meshed by a plurality of surface samples such as dS1, dS2, dS3, dS4, etc. Referring to FIG. 6b, with each surface sample dSi is associated a hemisphere HEMi tangent to the surface sample dSi at a point of contact Pi. Preferably, this point of contact Pi corresponds to the apex of the hemisphere HEMi. During this step of meshing of the surfaces b and a, the surface area of the structural element is evaluated on the one hand and on the other hand a number of surface samples dSi is chosen according to the desired position of the estimation of the electric field. Thus, the surface area of a sample dSi is given by S0/N where S0 corresponds to the total surface area of the surface b to be studied, and N corresponds to the chosen number of surface samples dSi. The hemisphere HEMi has the same surface area as the sample dSi. Thus, the radius Ri of the hemisphere is deduced from the expression 2πRi2=S0/N. Each mesh cell represented by a surface sample dSi exhibits, in the example described, a parallelogram shape, with centre Pi corresponding to the point of intersection of the diagonals of this parallelogram. The hemisphere HEMi is tangent to the surface sample dSi at this point Pi. Of course, the mesh cells may be of various shapes, triangular or otherwise. It is indicated in a general manner that the point Pi corresponds to the barycentre of the mesh cell. It may be useful to restart directly from a mesh of the structural element developed during the design of the structure. When the boundary conditions of the problem pertain to a vector quantity, three sources SAi, SBi, SCi are assigned to the surface sample dSi. The three sources SAi, SBi, SCi, allocated to a surface sample dSi have respective positions determined as indicated below. As represented in FIG. 6b, the three sources SAi, SBi, SCi are coplanar and the plane comprising these three sources furthermore comprises the base of the hemisphere HEMi. The hemisphere HEMi is constructed with the centre of the disc constituting the base of the hemisphere which corresponds to the barycentre of the three sources SAi, SBi, SCi. For a neighbouring hemisphere HEM2, the three sources SA2, SB2, SC2 may be oriented in a different manner from the sources SA1, SB1, SC1 of the hemisphere HEM1, as represented in FIG. 6c, and as a general rule, the sources of the various hemispheres may be oriented in a random manner so as to avoid an overperiodicity phenomenon. It is considered that the sources S′A1, . . . , S′CN, SA1, . . . , SCN are fictitious charges emitting an excitation field into the structure. The electric field at any points M1, . . . , MN of the medium are related to the intensities of the charges of the sources of the points A1, . . . , AN, B1, . . . , BN, C1, CN by the following expression: ( V x ( M 1 ) V x ( M 2 ) ⋮ V x ( M N ) V y ( M 1 ) V y ( M 2 ) ⋮ V y ( M N ) V z ( M 1 ) V z ( M 2 ) ⋮ V z ( M N ) ) = F ′ ( M ) · ( v ′ A 1 v ′ A 2 ⋮ v ′ A N v ′ B 1 v ′ B 2 ⋮ v ′ B N v ′ C 1 v ′ C 2 ⋮ v ′ C N ) [ 1 ] where: the coefficient v′Σj (Σ=A, B, C and j=1, 2, . . . , N) of the first column matrix corresponds to the value of electric charge qj for the source S′Σj; the coefficients Vu (Mi) (where u=X, Y, Z and i=1, 2, . . . , N) of the second column matrix correspond to a value of the electric field at a point Mi of space; the interaction matrix F′, of dimension 3N×3N is expressed by the relation: F ′ = ( N { C A x ( i , j ) ︷ N C B x ( i , j ) ︷ N C C x ( i , j ) ︷ N N { C A y ( i , j ) C B y ( i , j ) C C y ( i , j ) N { C A z ( i , j ) C B z ( i , j ) C C z ( i , j ) ) [ 2 ] The expression for these coefficients is as follows: C Σ u ( i , j ) = f u [ d ( P i , S Σ , j ) ] with [ 3 ] Σ = A , B , C i = 1 , 2 , … , N j = 1 , 2 , … , N u = x , y , z . C Σ u ( i , j ) = [ - grad _ ( 1 2 πɛ M i S Σ j _ ) ] u , [ 4 ] where ε=εr·ε0 corresponds to the dielectric permittivity of the medium wherein the point Mi is situated. Thus, the matrix system of equation 1 makes it possible to estimate, on the basis of an interaction matrix F′ and of a vector comprising the values v′Σj associated with the sources S′Σj, the coefficients of a vector (column matrix) comprising the values of the electric field V(Mi) at the point in space Mi. To determine the values of the sources v′Σj, the matrix system of equation 1 is applied to the points P′1, . . . , P′N corresponding to the apex of the hemispheres HEMi of the surface b, where the incident electric field can be known. The values of the sources v′Σ1, v′Σ2, . . . , v′ΣN are thus determined by the following equation: ( v A1 ′ ⋮ v AN ′ v B1 ′ ⋮ v BN ′ v C1 ′ ⋮ v CN ′ ) = F ′ ( P ′ ) - 1 x ( V x ( P 1 ′ ) ⋮ V x ( P N ′ ) V y ( P 1 ′ ) ⋮ V y ( P N ′ ) V z ( P 1 ′ ) ⋮ V z ( P N ′ ) ) [ 5 ] where the coefficients of F′−1(P′) are determined since the respective distances from the points P′1, . . . , P′N to the points A1, . . . , CN are known. Once these values of sources v′Σj have thus been determined, the expression for the electric field V′ at any point M in space is easily calculated. By referring again to FIG. 6a, it will be understood that the second surface a receiving the wave emitted by the first surface b acts, itself, as an active surface re-emitting a secondary wave by reflection. Each source SΣi represents a contribution to the emission of this secondary wave. To take account both of the presence of the main wave and of the presence of the secondary wave at the points M, the contribution of the main wave and the contribution of the secondary wave at the point M is estimated by the matrix system: V ′ ( M ) = Fx ( v A1 v A2 ⋮ v AN v B1 v B2 ⋮ v BN v C1 v C2 ⋮ v CN ) + F ′ x ( v A1 ′ v A2 ′ ⋮ v AN ′ v B1 ′ v B2 ′ ⋮ v BN ′ v C1 ′ v C2 ′ ⋮ v CN ′ ) [ 6 ] where: F is the matrix of interaction between the surface a and the points M; vΣj (Σ=A, B, C; j=1, 2, 3, . . . , N) is the value of the sources allocated to each surface sample dSj of the surface a, N being the total number of mesh cells chosen for this surface. The coefficients of the matrix F are dependent on the distance MSΣj where SΣj are the sources assigned to each sample dSj of the second surface a. In the case where the field emitted by the second surface is the reflection of the field emitted by the first, the values of the sources vΣj of the second surface a are determined as a function of values of the sources of the first surface b, as is detailed below with reference to FIG. 7. A value of reflection coefficient is assigned to each point Pi of the second surface a. In the particular case of a material made of carbon fibres embedded in a resin, this reflection coefficient is in particular dependent on the modelled electrical conductivity σS of the carbon fibres at this point and the modelled dielectric permittivity εSr of the resin at this point. A matrix Ra which is representative of the reflection coefficient at each point Pi is therefore introduced. At each point, R a = 1 - ( ɛ r - j σ ωɛ 0 ) 1 + ( ɛ r - j σ ωɛ 0 ) , [ 7 ] where j is the complex number such that j2=−1, ω is the angular frequency of the incident field, εr the relative dielectric permittivity of the material and ε0 the dielectric permittivity in vacuo. In what follows, it is indicated that: F(Pi) is the interaction matrix for the second surface a applied to the point Pi of the second surface; F(P′i) is the interaction matrix for the second surface applied to the point P′i of the first surface; F′(Pi) corresponds to the interaction matrix for the first surface applied to the point Pi of the second surface; F′(P′i) corresponds to the interaction matrix for the first surface applied to the point P′i of the first surface; v′ corresponds to the column vector comprising the values of the sources S′Σi of the first surface; and v corresponds to the column vector comprising the values of the sources SΣi of the second surface. At the level of the second surface of the structural element 1, the contribution of the incident wave emitted by the first surface b is expressed by: {right arrow over (V)}′(P)=F′(P).{right arrow over (v)}′ [8] The contribution of the secondary wave returned by the second surface a is expressed, by definition, by the relation: {right arrow over (V)}(P)=F(P).{right arrow over (v)} [9] Now, in the example represented in FIG. 7, the secondary wave corresponds simply to a reflection of the main wave, this being expressed by the relation: {right arrow over (V)}(P)=Ra{right arrow over (V)}′(P) [10] where Ra corresponds to a reflection matrix each coefficient of which represents the contribution to the emission, by reflection, of the secondary wave, by each source SΣi of the second surface. From the three relations above we deduce the expression for the column vector v comprising the values of the sources on the second surface, on the basis of the column vector v′ comprising the values of the sources of the first surface b by the relation: {right arrow over (v)}=[F(P)]−1.Ra.[F′(P)].{right arrow over (v)}′ [11] Thus, the value of the field V′ (P′) on the first surface b is determined directly as a function of the values of the sources v′ of the first surface b in the case where the initial electric field is emitted over a single surface of the structure under study. FIG. 8 presents in a general manner the case of the calculation of the equivalent sources for a structure 1 subjected to an electric field simulated by initial charges v′0 on the surface b and v0 on the surface a. In a general manner, if an exterior field is also applied to the second surface, then superposed on Equation 11 is Equation 6 applied to the sources of the second surface: V′(P′)=F′(P′)v′. In a general manner, the field reflected on the second surface a of the structure will again be reflected on the first surface b as if emitted by sources v′2 according to: Rb V′2(P′)=F′(P′)v′2, i.e. v′2=F′−1(P′)Rb V′2(P′), Or again v′2=F′−1(P′)Rb F′(P)v1 [12] v1 are the sources of a field itself corresponding to a reflection of the field emitted by the original sources v′0 according to: Ra V1(P)=F(P) v1, i.e. v1=F−1(P)Ra V1(P), or again v1=F−1(P)Ra F(P′)v′0 [13] By combining [12] and [13], we obtain the fictitious source v′2 as a function of the initial source v′0 according to: v′2=F′−1(P′)Rb F′(P)F−1(P)Ra F(P′)v0, We can write v′2=B A v′0, with the matrices A=F−1(P) Ra F(P′) and B=F−1(P′) Rb F′(P). Likewise on the exterior surface a, v2=F−1(P)Ra F(P′)F′−1(P′)Rb F′(P)v0, i.e. v2=A B v0. The effective source corresponds to the sum of the various terms originating from the various reflections: VTotal=v0+v1+v2+ . . . , VTotal=v0+A v′0+AB v0+ . . . By similarly writing the sources v′Total on the other surface, these two equations can be grouped together in the form: ( v Total v Total ′ ) = [ ( 1 0 0 1 ) + ( 0 A B 0 ) + ( AB 0 0 BA ) + ( 0 ABA BAB 0 ) + … ] ( v 0 v 0 ′ ) i . e . ( v Total v Total ′ ) = P ( v 0 v 0 ′ ) . [ 14 ] In practice, one will be limited to a finite number of reflections, corresponding to a finite number of terms for the matrix P, since each reflected field is of course attenuated with respect to the incident field. In practice one will choose not to consider any reflection, i.e. P = ( 1 0 0 1 ) , one reflection, i.e. P = ( 1 A B 1 ) , or more, depending on the nature of the material, the thickness considered, the desired accuracy of the result, among other things. Finally, the electric field V is calculated at the points chosen as a function of the initial sources ( v 0 v 0 ′ ) by the formula: ( V V ′ ) = ( F ′ ( P ′ ) F ( P ′ ) F ′ ( P ) F ( P ) ) ( v Total v Total ′ ) = M 0 P ( v 0 v 0 ′ ) , where ( F ′ ( P ′ ) F ( P ′ ) F ′ ( P ) F ( P ) ) = M 0 . [ 15 ] Thus, the potential at any point in space lying between the surfaces a and b can be calculated as a function of the value of the initial sources v0 and v′0. The DPSM technique just described may be used in three different ways. I/ FIG. 9 represents the application of the above concepts to the case where the first surface b is the emission layer 4, the second surface a is the internal face 1b of the structural element 1, the medium being air or a resin in which the tracks of the detection layer 5 are held. One seeks to calculate the electric field at the point M of the detection layer 5. As the expression for the current i traversing the emission layer 4 is known, it is possible to analytically calculate, for example by the Biot and Savart law, the incident electric field on the internal face 1b of the structural element. The reflection coefficient is applied to the incident field to determine the reflected field. The value of the sources SA1, . . . , SCN situated in the structural element and corresponding to elemental charges emitting the electric field reflected at the level of the face 1b is then calculated. The value of the electric field at the points M of the detection layer like the electric field emitted by these sources is next calculated by the DPSM method. Alternatively, recourse may be had to a DPSM modelling of the emission layer 4, as represented in FIGS. 10a and 10b. The emission layer 4 is modelled by elements each comprising a sphere exhibiting three current elements dI of length δ, intersecting the centre G′i of the base of the sphere so as to form a trihedron there. The orientation of the trihedrons may possibly vary from one element to another, to avoid overperiodicity problems. The length of each element is related to the diameter of the sphere and is calculated as a function of the boundary conditions imposed by the conducting tracks present at the level of the emission layer, or more generally by knowing at the points P′i the incident field due to an emission device. Likewise, the incident electric field at the level of the internal face 1b is calculated by DPSM method on the basis of the values of the currents traversing the current elements. Then, the electric field is calculated in the detection layer as previously, on the basis of the reflection coefficient. To summarize, one proceeds as follows: the position of the points Pi and of the sources Si is determined after meshing the faces; the coefficients of the matrix F(P) are determined; the coefficients of the reflection matrix Ra are determined as a function of a reflection law of the obstacle; the values of the vector V(P) at the points Pi of the internal face 1b are determined as a function of the boundary conditions on the internal face 1b, for which the incident electric field can be calculated, and the values of the sources SΣi of the internal face 1b are deduced from the aforesaid values; once the values of all the sources SΣi have been determined, the matrix system given by relation 1 may be applied to every point M of the detection layer, by applying the interaction matrix F (involving the position of the point M and the positions of the respective sources SΣi) to this point M. The model thus developed can be used jointly with the device for integrated monitoring of structures 2 to quantify the damage suffered by the structure. To do this, if it is detected that the structure has suffered damage, for example because a difference is noted between the measured components Ex and Ey of the electric field at the level of the detection layer 5 with the same electric field components measured previously, such as during a previous inspection, or by comparison with values contained in a database and established during manufacture of the structure, one can proceed as follows: We start from a model of the healthy structure, which is contained in the control unit 3 and is established for example when the structure is brought into service. This model exhibits, by way of example, a modelled electrical conductivity σs0=104 S.m−1, and a modelled dielectric permittivity εsr0=4, or any other preestablished values for the matrix and the fibres used. The model can be modified simply by modifying the reflection matrix Ra, simply by modifying one or the other of the said parameters σs and εrs at the level of the presumed damage suffered by the structure (location identified by the structure integrated monitoring device 2). The model thus established is represented in FIG. 11, where a healthy area 28 surrounding a damaged area 13 are represented diagrammatically. Purely mechanical damage having little influence on the component Ey of the electric field detected (with of course the orientation represented in the figures), it is in particular possible to implement the algorithm proposed in FIG. 12. Starting, at 14, from a measurement of the component EY of the electric field, this component EYm is compared, at 15, with a previous value of E0Ym, for example obtained during a previous examination, and contained in a database. If the difference ΔEY=EYm−E0Ym is significant, for example greater than a preestablished threshold ΔEy0 we can forthwith at this juncture conclude at 16 that there is a defect of a nonmechanical origin, namely a chemical and/or thermal origin in the structure and that has given rise to a variation in the dielectric permittivity εr of the resin. At 17, the component Ey of the electric field is calculated for the model of the structure exhibiting a defect corresponding to a local variation in the permittivity εr, having fixed for example εrd=2. At 18, the component εY, calculated at 17 for this model exhibiting a defect, is compared with the component EYm measured by the structure integrated monitoring device 2. If the difference between these two values is less than a predetermined threshold, fixed for example by experience, then the value εr of the structure is deduced from this, at 19, as being that used in the model at 17. Otherwise, the model is modified at 20 by locally modifying the value of εrd assigned to the defect, and the calculation is redone at 17. It is thus possible to do a certain number of calculations so as to get closer to the value of dielectric permittivity actually present in the structure at the level of the defect, until the condition 18 is finally complied with. Returning to the level of the comparison 15 between the measured value EYm and a previously measured value of the same component, if no notable differences are apparent between these two components, and if there is nevertheless a difference between the measured component EXm and a previously measured component E0Xm for the structure, a defect of a mechanical origin can be concluded at 21 for the structure. Likewise, at 22 a component EX is calculated for the model exhibiting a defect of a mechanical origin, such as for example a conductivity σsd=102 S.m−1, and the component calculated for the model of the structure exhibiting a defect and the measured component are compared at 23. If the difference between the measured component EXm and the component calculated for the model of the structure exhibiting a defect is less than a certain predetermined threshold, we deduce from this, at 24, that the value of the electrical conductivity of the structure at this point is about equal to the value of the electrical conductivity used in the model at 22. Otherwise, the model is modified at 25, in particular by modifying the value of the electrical conductivity σd at the level of the defect, and the component EX is calculated again at 22, for the modified model. It is thus possible to carry out a certain number of iterations until a calculated component EX is obtained which is close to the measured component EXm of the electric field, and to deduce therefrom the value of the electrical conductivity of the area of the, structure equal to the value of σ used during the last iteration of the model. Once the component EX has been successfully identified at 23, it is possible to verify that the structure does not additionally exhibit a defect of a chemical and/or thermal origin. To do this, the component EY calculated for the defect of a mechanical origin, is compared at 29 with the measured component EYm. Should there be a difference, the dielectric permittivity of the structural element under test is calculated in the same way as previously (17-19). It is moreover possible to employ a database in which, for a structure equivalent to the structure under test, the modifications of the electrical conductivity σ and/or the dielectric permittivity εr respectively have been measured for defects following monitored inputs of energy of a mechanical, chemical and/or thermal nature. On the basis of the values obtained at 19 and 24, it is thus possible, with the aid of this database, to get back to the energy undergone by the structure, and to deduce therefrom the energy received by the structure. It is thus possible to objectively determine whether the tolerance threshold for the structure has not been reached, or whether it is essential to envisage a repair and/or a replacement. II/ In the foregoing, the calculations were performed outside of the structural element, the latter influencing the calculation only through the matrix Ra of reflection at its surface. Nevertheless, the DPSM method can be used to more accurately represent the internal physical phenomena within the structure. In this case, FIG. 6a and FIG. 8 are employed again, in which the surface b corresponds to the internal face 1b of the structural element 1, the surface a corresponds to the external face la of the structural element 1, and the medium corresponds to the structural element 1, regarded as homogeneous through its thickness. A portion of the electric field incident on the internal face 1b, calculated analytically as before, is transmitted within the structural element 1. The field transmitted in the structural element is calculated by applying a transmission coefficient T (related to the ratio of the transmitted wave to the incident wave while the reflection coefficient R is related to the ratio of the reflected wave to the transmitted wave) to the incident field calculated analytically or by DPSM as previously. The initial sources S′0Σi correspond to sources emitting into the structural element the transmitted portion of the electric field incident on the face 1b from the emission layer 4. The initial sources S0Σi are zero, since no emission layer is employed on the external face 1a of the structural element. The effective sources SΣi and S′Σi are calculated by formula [14] and the electric field at every point of a medium by formula [15], choosing an appropriate number of reflections. When there are multiple reflections, the wave incident on the internal face 1b from inside the structural element 1 is also partially transmitted. Finally, the electric field in the detection layer is calculated as in relation to FIG. 9, with the aid of electric field sources emitting towards the detection layer the electric field transmitted towards the detection layer from the field incident on the face 1b from inside the structure 1, and of the local coefficient of transmission T′ of the structural element towards the outside. The optimization calculation presented in relation to FIGS. 11 and 12 is then applied. III/ The DPSM method also makes it possible to carry out tomography through the thickness of the structure 1. In particular, the structure 1 being a multilayer structure, the modelled structure can be sliced up into as many layers as the structural element 1, so as to qualify each layer. Nevertheless, there is not necessarily any link between the layering of the structural element 1 and that of the model. Reference is made to FIG. 13 for the analysis of this embodiment. Initially, the structure is excited by a current at a high frequency suitable for loading the structure chiefly at the surface. A frequency is for example chosen such that the attenuation of the field in the structure between the internal face 1b and the other face 1c of the modelled surface layer is sufficient for it to be possible to neglect the influence of the layers situated under the surface layer (for example an attenuation about equal to 10). The steps of I/ or of II/ are performed for the surface layer alone. By way of example, the surface a of FIG. 6a is then the face 1c of the structural element 1. The values of conductivity σ and permittivity εr are thus obtained at the level of the surface layer. Next, the structure is excited at a lower frequency, so that the attenuation by a factor of for example 10 is for example obtained between the face 1b and a yet deeper face 1d of the structure. By repeating the calculation of I/ or of II/ for that part of the structural element lying between the faces 1b and 1d, information is obtained about the values of conductivity σ and permittivity δr for these two layers aggregated. With the aid of the previous calculation of the conductivity σ and permittivity εr values in the surface layer, these values are deduced for just the intermediate layer lying between the faces 1c and 1d. One continues thus, lowering the frequency successively, to obtain for each new layer, the sought-after conductivity σ and permittivity εr values. Of course, one might wish to search for only one of these values, and it would, for this purpose, be possible to measure and calculate only one of the two components EX or EY, and deduce therefrom only one component εr or σ by applying the left branch or the right branch of the algorithm of FIG. 12. Alternatively, it would be possible to begin with a low frequency to obtain an overall picture of the structure, then to gradually increase the frequency to obtain information about the successive layers closer and closer to the emission layer 4. Other variants are possible, such as for example scanning the structure firstly by increasing the frequency in successive steps and then by reducing it down to its initial value, or other variants. According to one variant, the device for integrated monitoring of structures is not necessarily fixed on an internal 1b or external la face, but may be inserted into the structure, in which case the previous calculations will have to be carried out by summing the results provided for the two portions of structure separated by the device, each exhibiting a reflection matrix and a transmission matrix. Thus the central unit 3 is on the one hand suitable for controlling the excitation of the conducting tracks 9 of the emission layer 4, of the conducting tracks 12 of the detection layer 5, the switching of the breakers 11, and the processing of the signal detected, and on the other hand comprises calculation means comprising memory means that can contain a model of the structure under study, means for estimating the components EX and EY, means of comparing these values with the measurements, means of generating a modified model. Finally, the central unit can comprise a database of earlier results for the structure under test or of the results obtained for one or more similar structures. Certain of these elements may furthermore be placed on an information support such as a CD-ROM, a DVD-ROM, or other, able to be read by a computer. The information provided by the method and the device according to the invention could also be used jointly with that provided by the SMART-layer device for integrated monitoring of structures from the company Acellent based on piezoelectric sensor technology, whose ability to detect defects of a mechanical origin is recognized. The method and the device described here are not confined exclusively to use for composite structures comprising on the one hand a matrix consisting of a dielectric material and, on the other hand, of carbon fibres exhibiting electrical conductivity. It is for example possible to use the device and the method according to the invention for a sandwich structure, such as represented in FIG. 14, which is purely dielectric. In this case, there is of course no question of determining any electrical conductivity σ for the carbon fibres, but the device according to the invention can be used to determine the dielectric permittivity εr of the structural element 1. The latter can for example consist of one or more layers 26 of resin reinforced with glass fibres, and of a core 27 disposed between these layers. In this case, the device for integrated monitoring of structures no longer operates according to a hybrid technology, but according to a purely electrical method, in which the emission layer 4 is modified to generate an electric field E rather than a magnetic field. This is carried out very simply by opening the switches 11 (FIG. 4) previously linking the conducting tracks 9a and 9b, so as to generate an electric field in each of the conducting tracks 9a, 9b, etc. successively. The solution algorithm of FIGS. 8 and 9 is now used only to determine the value εr of the dielectric permittivity of the instrumented structure. Under these conditions, it is now possible not to measure the component EX of the electric field detected, and we can make do with a detection layer oriented along the direction Y, such as that represented at 5a in FIG. 5a. Of course, the emission and detection layers 4, 5, may be situated on the internal face 1b of the sandwich structural element 1, or on its external face, or be split so as to be placed respectively at various levels in the thickness of the structural element 1. | <SOH> TECHNOLOGICAL BACKGROUND <EOH>More particularly, the invention concerns a device for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity ε r comprising: (A) means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (B) detection means suitable for measuring a first measured component of an electric field, along a first direction of detection. The structural elements in question are typically materials made of resin reinforced with glass fibres or carbon fibres, forming part of the structure, for example of a vehicle such as a motor vehicle, an aircraft, a railway vehicle, or the like, for which the weight constraints are paramount. Such a device has already been used with success in the past to determine whether such a structural element exhibited a defect, for example of a mechanical or chemical nature, or the like. Such an example of an application is described in “Electromagnetic health monitoring system for composite materials”, Lemistre and Balageas, in Matériaux et Techniques, special issue 2002, published by SIRPE, Paris, pg 29-32. In this article, the electromagnetic field is, for structures comprising carbon fibres, a magnetic field locally equivalent to the magnetic field emitted by a dipole extending along a given direction of the structural element and is emitted by two linear conducting tracks extending in this direction and traversed in opposite senses by an electric current. The electric field is measured orthogonally to this direction in the plane of the structure. The information thus gleaned is useful for determining whether the structure does or does not exhibit a defect. For structures comprising glass fibres or simply a resin, the exciter field is an electromagnetic field emitted by the tracks extending likewise in this direction. Such a device makes it possible to qualify the presence or otherwise of a structural defect in the structure under study, but does not make it possible to determine the gravity of the defect. In the presence of a defect, the user of the device will not know what to do: wait or replace the structure (thereby guaranteeing safety to the detriment of cost) even if the defect is not perhaps penalizing per se for the structure in its daily application. | <SOH> SUMMARY <EOH>Thus, according to the invention, a device of the kind in question is essentially characterized in that the said device furthermore comprises calculation means suitable for obtaining a value of the dielectric permittivity ε r in the said area on the basis of the said first measured component. By virtue of these arrangements, information pertaining to the structural element is obtained, making it possible to quantify the gravity of the defect exhibited by the structural element, since an intrinsic characteristic of the material is determined. In practice, this makes it possible to forecast the type of intervention to be undertaken with regard to the structural element, to eliminate the defect, rather than to have to replace the entire structural element through ignorance. In preferred embodiments of the invention, recourse may possibly be had moreover to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and the calculation means are alternatively or furthermore suitable for obtaining a value of the electrical conductivity σ in the said area on the basis of the said first measured component; the said detection means are suitable for furthermore measuring a second measured component of the said electric field, along a second direction of detection forming with the said first direction of detection a nonzero angle, and the calculation means are suitable for obtaining a value of the electrical conductivity σ and of the electrical permittivity ε r in the said area on the basis of the said first and the said second measured components; a direction chosen from the first and the second direction of detection is the said direction of means of emission; the said means of emission comprise a layer comprising, at said area, at least two parallel conducting tracks, oriented along the said dipole direction and suitable for being able to be traversed in mutually opposite senses by an electric current; the said detection means comprise a layer comprising, at said area, at least one conducting track oriented along the said first direction of detection, and a layer comprising, at said area, at least one conducting track oriented along the said second direction of detection; the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σ s representing the said electrical conductivity σ in this area, and ε r s representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission, along the said first direction of detection, and (F) comparison means suitable for comparing the said simulated component and the said corresponding measured component obtained by the means of detection (B); the calculation means comprise: (Z) memory means suitable for containing a model of the area by at least two numerical parameters related to σ s representing the said electrical conductivity σ in this area, and ε r s representing the said dielectric permittivity in this area, and a model of the said means of emission, (E) estimation means suitable for estimating a first and a second simulated component of the said simulated electric field along the said first and second directions of detection, and (F) comparison means suitable for comparing the said simulated components and the said corresponding measured components obtained by the detection means (B); the device furthermore comprises (D) generating means suitable for generating the said model contained in the memory means (Z); the device furthermore comprises (G) a database containing data relating to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity ε r for the said materials; the device furthermore comprises a layer for integrated monitoring of the structures based on piezoelectric technology; the said structural element comprises no imperfectly conducting material, and the means of emission are means of emission of electrical radiation that are suitable for generating an electric field extending in the said direction. According to another aspect, the invention relates to a structure suitable for health monitoring of an area of a structural element of the said structure, and comprising: the said structural element comprising at least one dielectric material of dielectric permittivity ε r , an electromagnetic radiation emission layer extending in a direction, the said electromagnetic field generating an electric field in the area, a detection layer suitable for measuring a first measured component of an electric field, along a first direction of detection, and at least one facility for connection to calculation means suitable for obtaining a value of the dielectric permittivity ε r in the said area on the basis of the said first measured component. According to embodiments, recourse may also be had to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, in which the means of emission are means of emission of magnetic radiation that are suitable for generating a magnetic field, the said magnetic field being, at the level of the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and in which the calculation means are alternatively or furthermore suitable for obtaining a value of the electrical conductivity σ in the said area on the basis of the said first measured component; the said structural element takes the form of at least one layer, the said detection layer being disposed between the said structural element layer and the said emission layer; the said structural element takes the form of at least one layer, the said emission layer being disposed between the said structural element layer and the said detection layer; the said structural element takes the form of at least one layer, the said structural element layer being disposed between the said emission layer and the said detection layer; the said inhomogeneous structural element takes the form of at least one fine layer comprising at least one imperfectly conducting material in the form of at least one carbon fibre, of electrical conductivity σ, and one dielectric material in the form of a matrix of dielectric permittivity ε r , in which the said carbon fibres are embedded. According to another aspect, the invention relates to a method for health monitoring of an area of a structural element comprising at least one dielectric material of dielectric permittivity ε r , comprising the steps during which: (a) an electromagnetic field is generated, by means of emission of electromagnetic radiation extending in a direction, the said electromagnetic field generating an electric field in the area, and (b) a first measured component of an electric field is measured, along a first direction of detection, characterized in that the method furthermore comprises a step (c) during which a value of the dielectric permittivity ε r in the said area is obtained on the basis of the said first measured component. According to preferred embodiments, recourse may moreover be had to one and/or other of the following arrangements: the said structural element is an inhomogeneous structural element furthermore comprising an imperfectly conducting material, of electrical conductivity σ, during step (a), a magnetic field is generated by means of emission of magnetic radiation, the said magnetic field being, at the level of the area, equivalent to a magnetic field emitted by a magnetic dipole extending in the said direction, and during step (c), a value of the electrical conductivity σ in the said area is alternatively or furthermore obtained on the basis of the said first measured component; during a first iteration, steps (a) to (c) are performed for a first frequency of the emission means, during a second iteration, steps (a), (b) and (c) are repeated for a second frequency, and during step (c) of the second iteration, the value obtained during step (c) of a previous iteration is taken into account; during each step (b), a second measured component of the said electric field is furthermore measured, along a second direction of detection forming with the said first direction a nonzero angle, and during step (c) of each iteration, the said first and second measured components are taken into account; during step (c), for each iteration, furnished, in memory means, with an initial model of the area through at least two numerical parameters related to σ s representing the said electrical conductivity σ in this area, and ε r s representing the said dielectric permittivity in this area, and a model of the said emission means, (e) at least one first simulated component of a simulated electric field generated in the said model of the area by the said model of means of emission is estimated, along a direction of detection chosen from the said first and second direction of detection, and (f) the said simulated component and the said corresponding measured component obtained during step (b) are compared; the method furthermore comprises, prior to step (e), a step (d) in which an initial model of the area by at least two numerical parameters related to σ s representing the said electrical conductivity a in this area, and ε r s representing the said dielectric permittivity in this area, and a model of the said means of emission, are generated in the memory means; during step (b), a second measured component of the said electric field is measured, along the other direction of detection, during step (e), a second corresponding simulated component of the said simulated electric field is estimated, and during step (f), the said second simulated component and the said second measured component obtained during step (b) are compared; subsequent to step (f), step (d′) is furthermore implemented, in which a modified model of the area is generated by at least two numerical parameters related to σ s representing the said electrical conductivity σ in this area, and ε r s representing the said dielectric permittivity in this area, differing from the initial model through at least one of the numerical parameters, and steps (e) and (f) are implemented for the said modified model; step (c) furthermore comprises a step (g) during which at least one characteristic of the area chosen from the conductivity σ and the permittivity ε r is determined by identifying the said simulated conductivity σ s with the said conductivity and/or the said simulated permittivity ε s r with the said permittivity, as soon as the comparison performed in step (f) gives a satisfactory result; the method furthermore comprises a step during which (h) an energy absorbed by the said structural element exhibiting the said electrical conductivity σ and/or the said dielectric permittivity ε r that are obtained in step (c) is determined by inference on a database containing data pertaining to an energy absorbed by a structural element exhibiting an electrical conductivity σ and a dielectric permittivity ε r for the said materials; the said structural element comprises no, even imperfectly, electrically conducting material, and, during step (a), an electric field is generated in the area, in the said direction, with the aid of means of emission of electrical radiation; during step (c), furnished, in memory means, with an initial model of the area by at least one numerical parameter related to ε r s representing the said dielectric permittivity in this area, and a model of the said means of emission, (d) a simulated component of a simulated electric field induced in the said model of the area by the said model of means of emission is estimated, and (e) the said simulated component and the said corresponding measured component obtained during step (b) are compared. | 20040330 | 20081202 | 20051013 | 62444.0 | 0 | HUYNH, PHUONG | DEVICE AND METHOD FOR HEALTH MONITORING OF AN AREA OF A STRUCTURAL ELEMENT, AND STRUCTURE ADAPTED FOR HEALTH MONITORING OF AN AREA OF A STRUCTURAL ELEMENT OF SAID STRUCTURE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,516 | ACCEPTED | Bonded clutch piston | A clutch assembly is provided including a first member and a second member rotatable relative to the first member. A clutch pack is provided for frictionally engaging the first and second members. A piston chamber is provided adjacent to the clutch pack, and a piston is disposed in the piston chamber and operable for applying axial pressure to the clutch pack. The piston includes first, second, and third seal portions integrally molded in place on the piston and engaging the piston chamber at spaced locations. The integrally molded first, second, and third seal portions reduce the number of components necessary for properly sealing the piston chamber and reduce the amount of labor required for assembly. | 1. A clutch assembly, comprising: a first member; a second member rotatable relative to said first member; a clutch pack including at least one first clutch disc attached to said first member and at least one clutch disc attached to said second member; a piston chamber adjacent to said clutch pack; a piston disposed in said piston chamber and operable for applying axial pressure to said clutch pack, said piston including first, second and third seal portions integrally molded in place on said piston and engaging said piston chamber at spaced locations. 2. The clutch assembly according to claim 1, wherein said first, second and third seal portions are molded from an elastomeric material. 3. The clutch assembly according to claim 1, wherein said piston chamber and said piston are annular in shape and said piston includes and inner diameter surface having said first seal portion disposed thereon and an outer diameter surface having said second and third seal portions disposed thereon. 4. The clutch assembly according to claim 3, wherein said outer diameter surface of said piston includes a radial offset portion, said third seal portion being disposed adjacent to said radial offset portion. 5. The clutch assembly according to claim 3, wherein said piston includes at least one aperture disposed in said outer diameter surface between said second and third seal portions. 6. The clutch assembly according to claim 1, further comprising a balance piston disposed between said apply piston and said clutch pack. 7. The clutch assembly according to claim 1, wherein said inner diameter surface, a side surface and an outer diameter surface between said first, second and third seal portions is coated with an elastomeric material integral with said first, second and third seal portions. | FIELD OF THE INVENTION The present invention relates to clutch assemblies for automatic transmissions and more particularly, to a sealing arrangement of a piston for use with a clutch assembly. BACKGROUND OF THE INVENTION In a typical clutch assembly for an automatic transmission (as illustrated in FIG. 2), a clutch pack 16 is provided for providing a frictional engagement between a first member 12 and a second member 14 which is rotatable relative to the first member 12. A piston 60 is provided within a fluid chamber 62 such that the application of fluid pressure to the fluid chamber 62 causes the piston 60 to move into engagement with the clutch pack 16 to frictionally engage the second member 14 to the first member 12. The contacting of the friction plates with increasing pressure eventually causes the rotation of the second rotatable member 14 which the system is designed to engage. A problem that has been recognized in the art for a typical clutch assembly of this type is that the centrifugal force of the fluid within the fluid chamber 62 can put a positive pressure on the apply piston 60 as illustrated in FIG. 2. The pressure generated by the centrifugal force of the fluid can cause unintended engagement of the clutch pack 16. Thus, a balance piston system has been developed as illustrated in FIG. 3 in which a balance piston 70 is disposed between the apply piston 60 and the clutch pack 16 so that hydraulic fluid is present on opposite sides of the apply piston 60. When the balance piston system is spinning, the balance piston 70 traps fluid at the outer edge of the cavity that it creates with the apply piston 60 to counteract the centrifugal forces caused by the fluid on the other side of the apply piston 60 as illustrated in FIG. 3. The balance piston 70 is provided with a seal member 72 that contacts an inner surface of the axially extending arm 64 of the apply piston 60. The seal 72 is critical for the proper functioning of the balance piston system. The apply piston 60 includes a first inner diameter seal 74 and second and third outer diameter seals 76, 78, respectively. Each of the seals 74, 76, 78 are loose seals which are received in a respective recessed groove 80a-c formed in the surface of the apply piston 60. In order to form these grooves 80a-c, the apply piston is formed in a casting process in which the grooves 80a-c can be cast or machined. The seals 74 and 76 combine to seal an apply chamber for the apply piston 60 while the seals 76 and 78 each engage an outer diameter surface of the piston chamber 62 along opposite sides of a fluid flow path 82 provided in the outer diameter surface of the apply piston 60. Fluid flow path 82 allows fluid to pass from piston chamber 62 to another piston chamber (not shown). Although the prior art piston and seal design is adequate for its intended purpose, it is desirable to provide a piston and seal design that is easier to manufacture and to assemble into a clutch system. SUMMARY OF THE INVENTION The present invention provides a clutch assembly for use in an automatic transmission for engaging a first member to a second member utilizing a clutch pack. A piston is disposed within a piston chamber and operable for applying axial pressure to the clutch pack. The piston includes first, second, and third sealing portions integrally molded in place on the piston and engaging the piston chamber at spaced locations. According to one aspect of the present invention, the first, second, and third seal portions are molded from an elastomeric material. According to yet another aspect of the present invention, the inner diameter surface, a side surface, and an outer diameter surface between the first, second, and third seal portions is coated with the elastomeric material which is integral with the first, second, and third seal portions. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: FIG. 1 is a cross-sectional view of a clutch assembly of an automatic transmission incorporating the bonded clutch piston with integral seal portions according to the principles of the present invention; FIG. 2 is a cross-sectional view of a prior art clutch design; and FIG. 3 is a cross-sectional view of a prior art clutch design utilizing a balance piston system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. With reference to FIGS. 1, the clutch assembly 10, according to the principles of the present invention, will now be described in which the same reference numerals are utilized to identify the same or similar elements as utilized in describing the prior art systems of FIGS. 2 and 3. The clutch assembly 10 includes a first member 12 and a second member 14 rotatable relative to the first member 12. A clutch pack 16 includes a plurality of clutch plates 18 having external splines which engage internal splines of the first member 12 and a plurality of clutch plates 20 having internal splines connected to external splines of rotatable second member 14. An apply piston 22 is provided in a piston chamber 24 provided in the first member 12. The apply piston includes a radially extending hub portion 22a and an axially extending arm portion 22b which presses against the clutch pack 16. A balance piston 28 is provided between the clutch pack 16 and the apply piston 22. The balance piston 28 includes an inner hub portion 28a with a central aperture 30 which is received on the shaft portion of member 12. A seal 31 is disposed adjacent to the central aperture 30. The balance piston 28 is disposed against a stop ring 32 and includes a spring seat portion 34 against which a return spring assembly 36 is disposed. Return spring assembly 36 also presses against the radially extending hub portion 22a of the apply piston 22 in order to bias the apply piston 22 to a disengaged position. Hydraulic pressure generated in the piston chamber 24 causes the apply piston 22 to move against the biasing force of the spring assembly 36 and into engagement with clutch pack 16 for causing frictional engagement between first member 12 and rotatable member 14. The balance piston 28 includes a radially extending outer portion 28B which is provided with a seal lip profile 38 which engages the inner surface of the axially extending arm portion 22b of the apply piston 22. A seal 31 is disposed around an inner diameter portion of the balance piston 28. The seal 38, along with balance piston 28 and apply piston 22 define a balance chamber 40 that contains a fluid that offsets the axial pressure generated by the centrifugal force on the fluid in the piston chamber 24. The piston 22 includes an inner diameter seal portion 42 integrally molded to the piston 22 along with first and second outer diameter seal portions 44 and 46. The first outer diameter seal portion 44 is provided at the interface between the radially extending hub portion 22a and the axially extending arm portion 22b. The second outer diameter seal portion 46 is provided adjacent to a radial offset portion 48 provided in the axially extending arm portion 22b. The piston includes one or more apertures 50 extending through the axially extending arm portion 22b of the piston 22 in a location disposed between the first outer diameter seal 44 and the second outer diameter seal 46. The apertures 50 communicate with a fluid flow path 52 provided in the first member 12 to allow fluid to pass from the balance chamber 40 to another piston chamber (not shown). The apertures 50 are preferably formed by a laser machining process although drilling or punching processes can also be used. The inner diameter seal portion 42 and first outer diameter seal portion 44 seal off the apply chamber 24 for activating the piston 22 which receives pressurized fluid through fluid supply passage 54. Each of the seals 42, 44, 46 are molded from an elastomeric material. The elastomeric material extends between the seal portions 42 and 44, as well as between the seal portions 44 and 46 as an integrated molding. With the apply piston 22 having integrally molded seals 42, 44, and 46, the manufacture of the piston 22 is simplified in that the piston can be formed of a stamped plate and the seal portions can be molded thereto so that no additional assembly is required. Furthermore, the seals 42, 44, and 46 are securely held in place during assembly of the apply piston 22 within the piston chamber 24 so that the seals are maintained in the proper orientation. The piston design of the present invention results in component reduction by reducing the number of components as compared to the prior art system, and also reduces labor since the piston no longer requires the installation of the loose seals. With the design of the present invention, a one-to-one balance dam to piston pressure diameter ratio is provided in order to create equal fluid head distribution within the balance dam chamber and the apply chamber. The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such Variations are not to be regarded as a departure from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>In a typical clutch assembly for an automatic transmission (as illustrated in FIG. 2 ), a clutch pack 16 is provided for providing a frictional engagement between a first member 12 and a second member 14 which is rotatable relative to the first member 12 . A piston 60 is provided within a fluid chamber 62 such that the application of fluid pressure to the fluid chamber 62 causes the piston 60 to move into engagement with the clutch pack 16 to frictionally engage the second member 14 to the first member 12 . The contacting of the friction plates with increasing pressure eventually causes the rotation of the second rotatable member 14 which the system is designed to engage. A problem that has been recognized in the art for a typical clutch assembly of this type is that the centrifugal force of the fluid within the fluid chamber 62 can put a positive pressure on the apply piston 60 as illustrated in FIG. 2 . The pressure generated by the centrifugal force of the fluid can cause unintended engagement of the clutch pack 16 . Thus, a balance piston system has been developed as illustrated in FIG. 3 in which a balance piston 70 is disposed between the apply piston 60 and the clutch pack 16 so that hydraulic fluid is present on opposite sides of the apply piston 60 . When the balance piston system is spinning, the balance piston 70 traps fluid at the outer edge of the cavity that it creates with the apply piston 60 to counteract the centrifugal forces caused by the fluid on the other side of the apply piston 60 as illustrated in FIG. 3 . The balance piston 70 is provided with a seal member 72 that contacts an inner surface of the axially extending arm 64 of the apply piston 60 . The seal 72 is critical for the proper functioning of the balance piston system. The apply piston 60 includes a first inner diameter seal 74 and second and third outer diameter seals 76 , 78 , respectively. Each of the seals 74 , 76 , 78 are loose seals which are received in a respective recessed groove 80 a - c formed in the surface of the apply piston 60 . In order to form these grooves 80 a - c, the apply piston is formed in a casting process in which the grooves 80 a - c can be cast or machined. The seals 74 and 76 combine to seal an apply chamber for the apply piston 60 while the seals 76 and 78 each engage an outer diameter surface of the piston chamber 62 along opposite sides of a fluid flow path 82 provided in the outer diameter surface of the apply piston 60 . Fluid flow path 82 allows fluid to pass from piston chamber 62 to another piston chamber (not shown). Although the prior art piston and seal design is adequate for its intended purpose, it is desirable to provide a piston and seal design that is easier to manufacture and to assemble into a clutch system. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a clutch assembly for use in an automatic transmission for engaging a first member to a second member utilizing a clutch pack. A piston is disposed within a piston chamber and operable for applying axial pressure to the clutch pack. The piston includes first, second, and third sealing portions integrally molded in place on the piston and engaging the piston chamber at spaced locations. According to one aspect of the present invention, the first, second, and third seal portions are molded from an elastomeric material. According to yet another aspect of the present invention, the inner diameter surface, a side surface, and an outer diameter surface between the first, second, and third seal portions is coated with the elastomeric material which is integral with the first, second, and third seal portions. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. | 20040330 | 20060509 | 20051006 | 69971.0 | 0 | LORENCE, RICHARD M | BONDED CLUTCH PISTON | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,711 | ACCEPTED | Roll-up flexible door and guides therefor | A roll-up door assembly including a flexible curtain made of synthetic rubber or fabric, a curtain winding mechanism and two guide members which extend vertically on opposite sides of the doorway. Side edge sections of the curtain are movable in respective guide members. Each guide has inner and outer wall sections with each wall section having an inwardly projecting, longitudinal rib. The two ribs of each guide form an elongate slot that receives a side edge section of the curtain. Spaced-apart pairs of curtain lock members are mounted on and distributed along each side edge section of the curtain. The lock members of each pair are positioned opposite one another on front and rear surfaces of the curtain respectively. The combined thickness of each pair of lock members and the curtain exceeds the width of the elongate slot. | 1. A roll-up type door assembly comprising: a flexible curtain made of rubber, synthetic rubber or fabric material and capable of closing a doorway, said curtain having upper and lower ends and two opposite side edges; a curtain winding mechanism having said upper end of said curtain attached thereto for raising said curtain by rolling said curtain up; two straight, extruded flexible guide members which are mounted so as to extend vertically on opposite, vertical sides of said doorway during use of said door assembly, two side edge sections of said curtain each being movable in a respective one of said guide members when said curtain is raised or lowered during use thereof; each guide member formed with integrally connected, inner and outer, longitudinally extending, resilient wall sections, each wall section having an inwardly projecting, longitudinally extending rib, the two ribs of each guide member forming an elongate slot through which a respective one of said side edge sections can extend during use of the door assembly; and spaced-apart pairs of curtain lock members mounted on and distributed along each side edge section of said curtain, the lock members of each pair being positioned opposite one another on front and rear surfaces of said curtain respectively, the combined thickness of each pair of said lock members and said curtain material exceeding the width of said elongate slot so that the pairs of lock members prevent said side edge sections of the curtain from escaping out of the guide members under normal windload or pressure conditions, wherein at least some curtain lock members engage with the ribs of their respective guide members when an excessive windload or impact is put upon the curtain and this engagement causes the wall sections of at least one guide member to separate from each other and thereby release the respective side edge section from the at least one guide member with little if any damage to the curtain or the guide members. 2. A door assembly according to claim 1 wherein each curtain lock member is made of a low friction, wear resistant, plastics material, has an elongate main body section having a rounded exterior surface as seen from an end of the respective lock member, and is mounted on its side edge section of the curtain so that its longitudinal axis is substantially parallel to the adjacent side edge of the curtain. 3. A door assembly according to claim 2 wherein each curtain lock member has a substantially flat wing section integrally connected to one side of said main body section and adapted to extend outwardly through said slot during use of said door assembly, and the combined thickness of the two wing sections of a pair of lock members and said curtain material is less than the width of said elongate slot. 4. A door assembly according to claim 1 wherein each guide member comprises a single elongate hollow member made of metal which is sufficiently flexible and resilient that pairs of the curtain lock members can be pulled out of their respective guide members by excessive windload or an impact with little, if any, damage to the guide member. 5. A door assembly according to claim 1 wherein each longitudinally extending rib forms a longitudinally extending concave surface which is concave as seen in a transverse cross-section of the respective guide member, and the two concave surfaces of the two ribs of each guide member form an elongate split socket arrangement for engaging pairs of said lock members located in the respective guide member during use of said door assembly. 6. A door assembly according to claim 1 wherein each curtain lock member is formed with at least two screw holes and the lock members of each pair are mounted on their respective side edge section and are connected to each other by at least two screws that extend through or into the screw holes of their respective lock members. 7. A door assembly according to claim 2 wherein each guide member has a base which is integrally connected to and joins the inner and outer wall sections of the guide member and said base has a plurality of threaded fastener holes formed therein and longitudinally spaced along the guide member, and wherein said door assembly includes threaded fasteners for mounting said guide members on support surfaces, said threaded fasteners in use extending into and engaging said threaded fastener holes. 8. A door assembly according to claim 1 including strips of low friction, wear resistant material affixed to both of said front and rear surfaces of said curtain adjacent said opposite side edges, said wear resistant material selected from a group of materials consisting of oliphatic polyetherurethane in dichlormethane (OPD), and polyethylene terepthalate polyester (PET) with a polyvinylchloride backing. 9. A door assembly according to claim 2 wherein each curtain lock member has two opposite end sections which are tapered and has two counter-bored screw holes for mounting the lock member to the curtain by means of screws. 10. A door assembly according to claim 1 including a rigid bottom bar mounted on said lower end of the curtain and having opposite ends which are located within the doorway and horizontally inwards from the guide members during use of the door assembly, wherein at least one pair of said lock members is mounted on each side edge section of the curtain at a location horizontally outwardly from a respective adjacent end of the bottom bar when said door assembly is in use. 11. A door assembly according to claim 2 wherein each curtain lock member has a bottom provided with a plurality of short pins that project into the adjacent side edge section of the curtain in order to assist in holding the curtain lock member in place on the curtain during use of the door assembly. 12. An elongate guide for use with a roll-up type door equipped with curtain lock mechanisms arranged along two opposite side edge sections of a flexible curtain for said door, said guide comprising an elongate guide member having: inner and outer, longitudinally extending, substantially planar wall sections with a cavity formed between the wall sections and adapted to slidably receive one of said side edge sections; a base section integrally connected to and joining said inner and outer wall sections; and two longitudinally extending ribs each integrally formed on a respective one of said inner and outer wall sections and together defining one end of said cavity as seen in transverse cross-section, the two ribs projecting inwardly towards each other and forming an elongate slot which is substantially narrower than the maximum width of said cavity as measured between the two wall sections and through which a respective one of said side edge sections can extend during use of the guide, wherein each rib has an elongate interior surface which is concave as seen in said transverse cross-section, and the concave surfaces of the two ribs form an elongate, split curved socket for engaging the curtain lock mechanism when the lock mechanism is located in the guide during use thereof, said split curved socket being capable of engaging said lock mechanism on both front and back sides of said curtain simultaneously. 13. An elongate guide according to claim 12 wherein said guide member is an integral, one piece, metal extrusion. 14. An elongate guide according to claim 13 wherein said guide member is made of aluminum alloy and is formed with screw holes distributed along the length of said base section and provided for attaching said guide member to a support frame. 15. An elongate guide according to claim 13 wherein said slot has a width ranging between {fraction (7/16)}th inch and ½ inch approximately and said cavity has a maximum width of about one inch as measured between the two wall sections with the wall sections in their normal unstressed state. 16. An elongate guide according to claim 12 wherein said wall sections are equal in width in the direction extending from said base section towards said slot and both ribs are formed on free inner edges of their respective wall sections. 17. A door curtain lock for retaining an edge section of a flexible door curtain in an elongate door guide mounted on a side of a doorway, said lock comprising a lock member made of a low friction, wear resistant plastics material, said lock member having an elongate, rigid main body section having an exterior surface which is rounded as viewed from one end of the lock member, said rounded exterior surface extending to at least one longitudinal side of the main body section, said lock member also having an inner surface adapted for mounting to a front or rear surface of said door curtain, wherein at least one hole for a mechanical fastener is formed in said main body section. 18. A door curtain lock according to claim 17 wherein said lock member has a substantially flat wing section integrally connected to one longitudinal side of the main body section and adapted to extend into an elongate slot formed in said door guide during use of said curtain lock, wherein said wing section projects outwardly from an inner edge of the main body section. 19. A door curtain lock according to claim 17 wherein there are two holes for mechanical fasteners formed in said main body section and said two holes are countersunk in order to accommodate heads of the mechanical fasteners. 20. A door curtain lock according to claim 17 wherein said lock member has two opposite end sections which taper longitudinally outwardly and in the direction of the inner surface of the lock member. 21. A door curtain lock according to claim 17 wherein two substantially flat wing sections extend outwardly from the two longitudinal sides of the main body section, at least one of said wing sections being adapted to extend into an elongate slot formed in said door guide during use of the curtain lock, and wherein both wing sections project from respective inner edges of the main body section. 22. A door curtain lock according to claim 17 wherein said lock member is made of copolymer polyacetal resin. 23. A door curtain lock according to claim 17 wherein a plurality of short pins are provided on and distributed over said inner surface, said pins assisting in holding the curtain lock in place on said door curtain during use of the door curtain. 24. A door curtain for use in a roll-up door apparatus, said curtain comprising: a flexible curtain made of rubber, synthetic rubber or fabric and capable of closing a doorway, said curtain having front and rear surfaces, upper and lower ends, and two opposite side edges, strips of low friction, wear-resistant material affixed to at least one of said front and rear surfaces adjacent said opposite side edges, said wear resistant material selected from the group consisting of oliphatic polyurethane in dichlormethane (OPD) and polyethylene terepthalate (PET) polyester with a polyvinylchloride backing; and a plurality of curtain lock members mounted on and distributed along said strips of wear-resistant material, said lock members being spaced apart from one another. 25. A door curtain according to claim 24 wherein said strips of wear resistant material are affixed to both said front and rear surfaces of the curtain. 26. A door curtain according to claim 24 wherein said strips of wear resistant material each include a base coat of rubber adhesive which is bonded to the adjacent surface of the curtain. 27. A door curtain according to claim 25 wherein said curtain lock members are arranged in spaced-apart pairs and the lock members of each pair are positioned opposite one another on said front and rear surfaces of said curtain respectively. 28. A door curtain according to claim 26 wherein said rubber adhesive is XL-2000™ rubber adhesive. 29. A door curtain according to claim 26 wherein each strip of wear resistant material is made by initially applying said OPD to said base coat of rubber adhesive, allowing said OPD and base coat to dry, and then bonding the combination strip comprising OPD and said rubber adhesive to said curtain using further rubber adhesive. 30. A door curtain according to claim 24 wherein each curtain lock member has an elongate main body section having a rounded exterior surface as seen from an end of the respective curtain lock member and is mounted on its strip of wear-resistant material so that its longitudinal axis is substantially parallel to the adjacent side edge of the curtain. 31. A door curtain according to claim 25 including a rigid bottom bar mounted on said lower end of the curtain and having opposite ends located inwardly from said side edges of the curtain. | PRIOR APPLICATION This application claims priority on the basis of previously filed U.S. Provisional Patent Application No. 60/485,721 filed Jul. 10, 2003. BACKGROUND OF THE INVENTION This invention relates to roll-up type door assemblies which are generally used in commercial and industrial applications, elongate guides for use in these door assemblies, and curtain locks for retaining edge sections of the flexible door curtains used in these door assemblies. It is well known in the door industry to provide a flexible, roll-up door that can be used to provide a passageway barrier in industrial, commercial, mining and other such facilities to accommodate the access of trucks, trains, forklifts and other such equipment to the facility or building or to provide passageway barriers within the facility or building. A flexible roll-up door typically consists of a synthetic rubber or fabric curtain which acts as a barrier across the passageway. The curtain is attached across its top edge to a rigid steel pipe spanning the width of the passageway. This steel pipe is typically known as a drive barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flanged type bearing attached to a steel plate, typically known as an endplate, which is attached to the, building structure directly above the passageway. Applying a controlled rotational movement of the drive barrel results in the curtain spooling onto the drive barrel, thus retracting the curtain upward to expose the passageway. Also, it may be inversely spooled off the drive barrel to dispense the curtain downward and close off the passageway. The lower, horizontal perimeter or bottom of the curtain is reinforced with structural steel members to provide rigidity to the section of curtain edge making contact with the ground. This component of a flexible roll-up door is typically known as a bottom bar and must be of sufficient rigidity to maintain adequate straightness of the curtain for the operation of the door. The bottom bar is configured to a predetermined mass to provide adequate gravitational force to pull the curtain to the ground. The bottom bar may include reversing, safety and/or sealing devices mounted thereon. The two vertical perimeters or edge sections of the curtain usually travel within suitable enclosures mounted adjacent to the passageway on each side. This component is typically known as a guide and serves the purpose of maintaining the required position of the vertical edge of the curtain while permitting unrestricted travel during door operation. The curtain is most often configured along its vertical edges with appropriate components, hereto referred to as curtain locks, to mate with the guides. Many flexible roll-up doors are constructed so that a predetermined releasing force can-cause the curtain to disengage itself from the guide or guides, for example, when the curtain is impacted by a vehicle or other device. The curtain is both retracted by and dispensed from the drive barrel over the forward side of a horizontal, rigid steel pipe spanning the width of the passageway. This pipe is located above the passageway and in close proximity to the building structure to provide an upper horizontal perimeter seal to the passageway and further serves as a curtain positioning mechanism, aligning the curtain with the guides mounted to the vertical sides of the passageway. This steel pipe is typically known as an idler barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flange type bearing attached to its respective mounting angle. The known flexible roll-up door systems can also include various other components to complete their functionality such as a counterbalance system, often through the use of torsion springs and/or weights, an operating mechanism that may consist of a manual hoist and/or electric motor with gear and/or chain power transmission arrangement, along with other secondary components. Known roll-up doors are commonly equipped with a curtain that has an element or elements attached to the vertical edges of the curtain (forming a curtain lock or locks) that co-operate with fabricated, often elaborate, guide assemblies. U.S. Pat. No. 5,392,836 which issued Feb. 28, 1995 to Rite Hite Corporation teaches the use of a series of hemispherical follower elements attached to side edge sections of the curtain of a roll-up type door. An external force can disengage these follower elements from the door guide by changing the relative dimension of the gap formed by the guide and the follower element or elements. This relative dimensional change is achieved by utilizing a multiple component, fabricated guide that is inherently incapable of precise production dimensioning and often becomes askew or out of alignment during service. Thus, it is believed that this known roll-up door system is incapable of precise operation and therefore lacks reliability. U.S. Pat. No. 5,482,104 issued Jan. 9, 1996 to Dale Lichy also describes a multi-component guide assembly which an external force, such as an impact from a vehicle, can disassemble to provide disengagement of an edge section of the curtain from its respective guide assembly. In one embodiment, each side edge of the curtain is provided with a lock strip which is bonded to one surface of the side edge. The strip is relatively narrow in width and has a thickness about the same as that of the curtain. In a second version of the curtain, there is a lock strip on the outer surface of the curtain edge and a further lock strip on the inner surface so that the strips form double wind locks. The two strips are not aligned with each other with the strip on the outer surface being spaced laterally inwardly from the edge of the curtain and the other strip having its outer edge generally aligned with the side edge of the curtain. It is an object of one aspect of the present invention to provide a novel roll-up type door assembly having a flexible curtain made of rubber, synthetic rubber or fabric material employing extruded guide members that are relatively easy to manufacture and install and that can be made at a reasonable cost and employing pairs of curtain lock members mounted on the side edge sections of the curtain which help hold the side edge sections of the curtain in the guide members. It is an object of another aspect of the present invention to provide an elongate guide for use with a roll-up type door which can be manufactured relatively easily using known manufacturing techniques and at a reasonable cost and which is capable of engaging a curtain lock mechanism with interior concave surfaces in a manner so that the guide is capable of engaging the lock mechanism on both front and back sides of the curtain simultaneously. It is an object of an additional aspect of this invention to provide an improved and novel door curtain lock for retaining an edge section of a flexible door curtain in a door guide, this lock being made of low friction, wear resistant plastics material and having a rounded exterior surface and an inner surface for mounting to a front or rear surface of the door curtain. SUMMARY OF THE INVENTION According to one aspect of the invention, a roll-up type door assembly includes a flexible curtain made of rubber, synthetic rubber or fabric material and capable of closing a doorway, this curtain having upper and lower ends and two opposite side edges. There is also a curtain winding mechanism having the upper end of the curtain attached thereto for raising the curtain by rolling the curtain up. The assembly also has two straight, extruded guide members which are made of flexible metal and, during use of the door assembly, are mounted so as to extend vertically on opposite, vertical sides of the doorway. Side edge sections of the curtain are each movable in a respective one of the guide members when the curtain is raised or lowered during use thereof. Each guide member is formed with integrally connected, inner and outer, longitudinally extending wall sections. Each wall section has an inwardly projecting, longitudinally extending rib with the two ribs of each guide member forming an elongate slot through which a respective one of the side edge sections can extend during use of the door assembly. Spaced-apart pairs of curtain lock members are mounted on and distributed along each side edge section of the curtain. The lock members of each pair are positioned opposite one another on front and rear surfaces of the curtain respectively. The combined thickness of each pair of lock members and the curtain material exceeds the width of the elongate slot so that the pairs of lock members prevent the side edge sections of the curtain from escaping out of the guide members under normal wind load or pressure conditions. At least some curtain lock members engage with the ribs of the respective guide members when an excessive wind load or impact is put upon the curtain and this engagement causes the arm sections of at least one guide member to separate from each other and thereby release the respective side edge section from the at least one guide member with little, if any, damage to the curtain or the guide members. Preferably, each curtain lock member is made of low friction, wear resistant plastics material and has an elongate main body section having a rounded exterior surface as seen from an end of the lock member. This lock member is mounted on its side edge section of the curtain so that its longitudinal axis is substantially parallel to the adjacent side edge of the curtain. According to another aspect of the invention, an elongate guide for use with a roll-up type door equipped with curtain lock mechanisms arranged along two opposite side edge sections of a flexible curtain for the door includes an elongate, metal guide member having inner and outer, longitudinally extending, substantially planar wall sections with a cavity formed between these wall sections. This cavity is adapted to slidably receive one of the side edge sections. The guide member also has a base section integrally connected to and joining the inner and outer wall sections and two, longitudinally extending metal ribs each integrally formed on a respective one of the inner and outer wall sections and together defining one end of the cavity as seen in transverse cross-section. The two ribs project inwardly towards each other and form an elongate slot which is substantially narrower than the maximum width of the cavity as measured between the two wall sections and through which a respective one of the side edge sections can extend during use of the guide. Each rib has an elongate interior surface which is concave as seen in transverse cross-section and the concave surfaces of the two ribs form an elongate split curved socket for directly engaging the curtain lock mechanism when the lock mechanism is located in the guide during use thereof. The split curved socket is capable of engaging the lock mechanism on both front and back sides of the curtain simultaneously. The preferred guide member is an integral, one-piece metal extrusion and the preferred metal is aluminum alloy. According to another aspect of the invention, a door curtain lock for retaining an edge section of a flexible door curtain in an elongate door guide mounted on a side of a doorway includes a lock member made of low friction, wear resistant plastics material. This lock member has an elongate, rigid main body section having exterior surface which is rounded as viewed from one end of the lock member. The rounded exterior surface extends to at least one longitudinal side of the main body section. The lock member also has an inner surface adapted for mounting to a front or rear surface of the door curtain. Also, at least one hole for a mechanical fastener is found in the main body section. Preferably the lock member has a substantially flat wing section integrally connected to one longitudinal side of the main body section and adapted to extend through an elongate slot formed in the door guide during use of the curtain lock. This wing section projects outwardly from an inner edge of the main body section. According to yet another aspect of the invention, a door curtain for use in a roll-up door apparatus comprises a flexible curtain made of rubber, synthetic rubber or fabric and capable of closing a doorway. The curtain has front and rear surfaces, upper and lower ends and two opposite side edges. Strips of low friction, wear-resistant material are affixed to at least one of the front and rear surfaces adjacent the opposite side edges, the wear-resistant material selected from the group consisting of oliphatic polyetherurethane in dichlormethane (OPD) and polyethylene terepthalate (PET) polyester with a polyvinylchloride (PVC) backing. A plurality of curtain lock members are mounted on and distributed along the strips of wear-resistant material, these lock members being spaced apart from one another. Further features and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a flexible, roll-up door constructed in accordance with the invention; FIG. 2 is a detail end view on a scale approximately three times the scale of FIG. 1, this view being taken along the line II-II of FIG. 1 and illustrating the relative position and attachment of some door components positioned at the top of the door opening; FIG. 3 is a cross-sectional detail view along section line III-III of FIG. 1 illustrating the relative positioning and attachment method of a door guide, a mounting angle for the guide and a door edge section; FIG. 4 is an enlarged end view of one door guide, this figure being on a scale about three times that of FIG. 3; FIG. 5 is an isometric illustration of one lower corner of the curtain, this view showing the bottom bar and some curtain locks; FIG. 6 is an enlarged detail view of the outer side of one curtain lock member; FIG. 7 is a side view of the curtain lock member of FIG. 6, this view being taken from the right side of FIG. 6; FIG. 8 is a side detail similar to FIG. 7 but showing two curtain lock members in position for attachment and illustrating two threaded fasteners for securing same; FIG. 9 is an isometric view illustrating one lower corner of the door curtain together with a section of a door guide and adjacent mounting angle, this view illustrating their assembled relationship; FIG. 10 is a cross-sectional detail similar to FIG. 3, this view illustrating the functional cooperation between the door guide, the cooperating edge section of the curtain and curtain locks mounted on the curtain, these components being subjected to normal external force bias; FIG. 11 is a detailed view of the circled area in FIG. 10 showing the cooperation between the guide and a pair of curtain lock members on an enlarged scale; FIG. 12 is a cross-sectional detail view similar to FIGS. 3 and 10 illustrating the functional cooperation between the door guide, the curtain and curtain lock members under extreme external force conditions which cause the edge section of the curtain to be pulled out of the guide; FIG. 13 is a detail view of the circled area of FIG. 12 showing the cooperation between the side walls of the guide and the curtain lock members under extreme external force conditions; FIG. 14 is an enlarged end view of a preferred door guide; FIG. 15 is an enlarged detail front view of another form of curtain lock member; FIG. 16 is a side view of the lock member of FIG. 15, this view being taken from the right side of FIG. 15; FIG. 17 is a side detail view showing two of the lock members of FIG. 15 in position for attachment and illustrating the fasteners to be used; FIG. 18 is a detail view similar to FIG. 11 showing the cooperation between the guide and a pair of the lock members of FIG. 15 to 17; FIG. 19 is an isometric view similar to FIG. 9 but illustrating the use of strips of low friction material .affixed to an edge section of the curtain, this figure showing one lower corner of the curtain and a section of one door guide; FIG. 20 is a detail cross-sectional view of an edge section of the door curtain shown in FIG. 19; FIG. 21 is a side detail view showing two preferred forms of lock members in position for attachment and illustrating the fasteners to be used; and FIG. 22 is a bottom view of one of the preferred lock members shown in FIG. 21. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIGS. 1 to 3 illustrate a preferred roll-up type door assembly 10 constructed in accordance with the invention and installed in the doorway of a building or other structure. The assembly 10 includes a flexible curtain 12 made of rubber, synthetic rubber or fabric material and capable of closing a doorway 14. It will be understood that the curtain has an upper end mechanically fastened to a drive barrel 16 and also a lower end 18 mechanically fastened to a rigid bottom bar 20. The curtain 12 is dimensioned to fit and completely cover the doorway 14 when the bottom bar is lowered to the ground or floor at 22. The doorway 14 is formed in a wall 24, only a portion of which is shown for ease of illustration. The upper end of the curtain, which extends horizontally during use of the curtain, can be wound up or lowered by the barrel 16 which is part of a curtain winding mechanism. Vertical side edge sections 26 of the curtain are movably mounted in two straight, extruded guide members 28 which are made of flexible metal, preferably aluminum alloy. When the door assembly is installed in the doorway, the two guide members extend along the two vertical sides of the doorway 14 and they are each mechanically fastened to a mounting angle 30. The cross-section of a preferred form of mounting angle can be seen clearly in FIG. 3 and it will be understood that this mounting angle can extend the full height of the doorway 14. The mounting angle is secured in an appropriate manner to the wall 24 of the structure. This wall can include a vertical steel channel 31 as shown in FIG. 9. The wall 24 can also be made of concrete or concrete blocks as shown in FIGS. 1,3 and 10 and the mounting angle 30 attached to the concrete surface. By way of example, the mounting angle on each side can be secured to the wall by fasteners 32, such as bolts, distributed along its length. Although the illustrated mounting angle 30 is preferred, it will be understood that other forms of frame means for mounting the guide members 28 on the vertical sides of the doorway can also be used. The mounting angle 30 can be made of structural steel. An idler barrel 34 can be located above the top of the doorway 14 and is secured by its solid steel end shafts 36 to the mounting angle 30 by means of flange type bearings 38 mechanically secured to the mounting flange. Also, in a known manner, each of the two ends of the drive barrel 16 is supported by a solid steel shaft 38 mounted in and supported by flange type bearings 40. The bearings 40 are mounted by suitable fasteners to respective end plates 42. Each end plate 42 is mechanically fastened by suitable fasteners, such as bolts 43, to the adjacent mounting angle 30. The illustrated roll-up type door is counter-balanced by use of a torsion spring 44 utilizing a chain drive 46 which is connected to the drive barrel 16. The use of a torsion spring in this manner is well known in the roll-up door industry and accordingly a detailed description herein is deemed unnecessary. It is also possible to utilize various known substitutes in lieu of the torsion spring 44. The roll-up door can be powered by an electric motor and gear box operator 48 which uses a chain drive 50 that is also connected to the drive barrel 16. Again, a power drive of this type is well known in the roll-up door industry. Referring to FIG. 5, this figure shows a bottom corner of the door curtain 12 with the bottom bar 20 attached thereto. The bottom bar typically comprises a couple of steel angle members 52 mounted on opposite sides of the lower end 18 of the curtain. The bottom bar can be secured to the curtain using bolts 54. It will also be noted that each end 56 of the bottom bar is spaced away from the adjacent side edge 58 of the curtain. Thus, the bottom bar does not extend into the metal guide member 28 but only extends between the two guide members. However, if desired, plastic arms (not shown) can be fastened to the ends of the bottom bar so as to extend into the guide members. Mounted on the bottom of the bar can be a known form of safety strip device 60 that can, for example, cause the door to stop or retract upwardly if the safety strip device strikes an object such as a vehicle or person. The strip device 60 can also serve as a bottom seal. As indicated, the two vertical side edge sections of the curtain are each movable in a respective one of the guide members 28 when the curtain is raised or lowered during use thereof. Each guide member is formed with integrally connected, inner and outer, longitudinally extending wall sections 62 and 64. Each of these wall sections is generally planar and each has an inwardly projecting, longitudinally extending rib 66. The two ribs 66 of each guide member form an elongate slot 68 through which a respective one of the side edge sections of the curtain can extend during use of the door assembly, as shown in FIG. 3. A cavity 70 is formed between the wall sections 62, 64 and is adapted to slidably receive this side edge section of the curtain. A base section 72 is integrally connected to and joins the inner and outer wall sections of the guide member. The base section forms a substantially flat end wall 74 suitable for mounting the guide member on the mounting angle 30. The illustrated guide member has corner projections 76 with each projecting beyond the outer surface of the adjacent wall section and helping to support the guide member in the required perpendicular position in which it is mounted on the mounting angle. A centering groove 78 can also be provided, if desired, midway between the corner projections and this groove can be used to properly locate a series of spaced apart threaded holes 80 that are used to mount the guide member on the mounting angle. A number of bolts 82 extend through holes in the mounting angle and can be threaded into the holes 80 to secure the guide member. If desired, the leg 84 of the mounting angle 30 (see FIG. 3) that is fastened to the wall 24 can be reversed as indicated by the dash lines, thus moving the fastening point for the mounting angle further away from the vertical edge 86 of the door opening. This alternative position is available to the door installer on the site where the door system is being installed and it may allow him or her the option of selecting a possibly more stable or stronger building material for fastening the mounting angle and its guide. This mounting arrangement is typically not available for other door guides now in use for flexible doors. The slot 68 formed by the two ribs is substantially narrower than the maximum width W of the cavity as measured between the two wall sections. The illustrated preferred cavity 70 is of substantial uniform width W, although internal corners at 90 are preferably rounded. The rounded corners or inner radii 90 have a radius that is chosen for both desired elastic properties and structural integrity of the respective wall sections that are connected at these corners. Preferably the horizontal length of the cavity 70, that is the distance measured between the base and the slot 68 is substantially greater than the width W of the cavity in order to properly accommodate the side edge section of the curtain. In the guide shown in FIG. 4, each rib 66 has an interior surface 94 which is elongate and concave, as seen in transverse cross-section (see FIG. 4). The concave surfaces 94 of the two ribs form an elongate split, curved socket for directly engaging the curtain lock mechanism when the lock mechanism is located in the guide during use thereof. Two forms of this curtain lock mechanism are described in detail below. The split curved socket is capable of engaging the lock mechanism indicated generally at 96 in FIG. 3 on both front and back sides of the curtain 12 simultaneously. The preferred guide member is an integral, one piece metal extrusion which can be manufactured at a reasonable cost. The preferred guide members are made of aluminum alloy that has been appropriately heat treated to provide mechanical properties that are advantageous for the function and operation of the guide member (explained more fully below). One desirable property of the guide member is its ability to reinstate and maintain its precise geometric characteristics and dimensions after deformation from induced stresses. A particularly preferred version of each guide member is made out of 6061 T6 aluminum alloy, an alloy having the desired properties. The width of the narrow access slot 68 formed by the ribs is significant and in one version of the guide member, this width is {fraction (7/16)}th inch in the relaxed, normal state of the guide member and in another preferred version this width is ½ inch. Preferably the guide member also has a horizontal length, as seen in FIGS. 4 and 14, of four inches and an external width X (including the cavity 70 and the two wall sections) of 1¼ inch. This particular guide member has an internal cavity width W of one inch. It will be understood that the inner and outer walls sections 62, 64 are extruded so as to have an appropriate thickness to provide both the desired elastic properties and structural integrity for the guide member to perform its function as explained more fully below. The wall sections 62, 64 are preferably equal in width in the direction extending from the base section of the guide towards the slot 68 and the two ribs are preferably integrally formed on the free inner edges of their respective wall sections (relative to the doorway 14). A preferred form of one piece guide member 140 is illustrated in FIG. 14. Except as indicted hereinafter, this guide member and its preferred dimensions are substantially the same as indicated for the guide member 28 of FIG. 4. The guide member 140 also has integrally connected, inner and outer, longitudinally extending wall sections 62 and 64. Each of these wall sections has an inwardly projecting, longitudinally extending rib 142 and these ribs form the elongate slot 68 through which a respective one of the side edge sections of the curtain can extend during use of the door assembly. The major difference between the guide member 28 and the guide member 140 is the shape and the construction of the two ribs. In the guide member 140, each rib 142 has an interior surface 146 which is elongate and concave as seen in the transverse cross-section of FIG. 14. In this preferred embodiment, the concave surfaces 146 extend substantially the height of each rib, this height h being indicated in FIG. 14. The concave surfaces 146 again form an elongate, split, curved socket for directly engaging the curtain lock mechanism when the lock mechanism is located in the guide. This split curved socket is capable of engaging the lock mechanism as illustrated in FIG. 18 on both front and back sides of the curtain 12 simultaneously. Preferably the lock mechanism for each side edge section of the door curtain comprises spaced-apart pairs of curtain lock members mounted on and distributed along each side edge section of the curtain. One version of individual lock member 100 is illustrated by itself in each of FIGS. 6 and 7 while a combined pair of these curtain lock members is illustrated in FIG. 8. It will be understood that the lock members of each pair are preferably positioned directly opposite one another on front and rear surfaces of the curtain 12 as can be seen in FIGS. 3 and 10 to 13. Because of the manner in which the lock members 100 are mounted on the curtain, the combined thickness indicated at Y in FIG. 11 of each pair of lock members and the curtain material exceeds the width of the elongate slot 68 so that the pairs of lock members 100 prevent the side edge sections of the curtain 12 from escaping out of the guide members 28 under normal windload or pressure conditions. It will be understood that at least some, if not the majority, of the curtain lock members 100 engage with the ribs 66 of their respective guide members when an excessive windload or impact is put upon the curtain 12 and this engagement causes the wall sections of at least one guide member to separate from each other and thereby release the respective side edge section (or part thereof) from the guide member with little, if any, damage to the curtain or the guide members. Three versions of the lock member will be described in detail but it will be understood that other lock member constructions are also possible and can be used in combination with the illustrated and described guide members. Each curtain lock member is made of a low friction, wear resistant plastics material. One preferred material for each curtain lock member is Kocetal-polyoxymethylene (POM) which is a copolymer-type polyacetal resin manufactured by Kolon Industries, Inc. and Toray Industries Inc. The lock member 100 of FIG. 8 has an elongate, main body section 102 having a rounded exterior surface 104 as seen from one end or either end of the respective lock member. The lock member is mounted on its side edge section of the curtain so that its longitudinal axis indicated at A in FIG. 6 is substantially parallel to the adjacent side edge 58 of the curtain. The rounded exterior surface 104 extends to at least one longitudinal side of the main body section and, in the illustrated embodiment, extends to both longitudinal sides of the main body section. The lock member 100 also has an inner surface 106 which is adapted for mounting to a front or rear surface of the curtain. Also, there is at least one hole, and preferably two holes 108, for a mechanical fastener or fasteners formed in the main body section. With reference to FIG. 8, there can be seen an assembled pair of curtain lock members 100 which are geometrically symmetrical when mechanically attached in an inverted fashion using two machine screws 110 to extend through the two holes 108. Preferably, the screws are threaded into matching binder posts 112 which are internally threaded and can be made of a suitably strong metal. Both the machine -screws and the binder posts are concealed within counter bores 114, 116 formed in the lock members. The joined pair of curtain lock members 100 have the aforementioned combined width Y when mounted on the curtain. In this embodiment, each lock member is formed with an integral protrusion 118. Although the dimension Y can vary and depends on such factors as the thickness of the curtain 12, in one preferred curtain the dimension Y measures ¾ inch and it is used with a guide member having a slot width of {fraction (7/16)}th inch or preferably ½ inch. The length of each protrusion 118 in this first embodiment is made or adjusted so that it corresponds closely to the thickness of the curtain with which the lock member will be used. It will be understood that a pair of holes is formed in the side edge section of the curtain for each pair of lock members to accommodate the fastening of same. It should be noted that the dimension Y is selected so that the curtain edge sections can travel freely within their respective guide members 28 during normal use and operation of the door with the lock members experiencing only casual contact with the inside of their respective guide member. This slightly loose fit of each pair of lock members in their respective guide member is visible in FIG. 11. Preferably, each lock member is also formed with at least one substantially flat wing section 120 integrally connected to a longitudinal side of the main body section 102. In the illustrated lock member 100 there are two of these wing sections 120, each extending from its respective longitudinal side of the main body section. At least one of these wing sections is adapted to extend through or into the elongate slot 68 formed in the respective door guide during use of the curtain lock. This passage of the wing section through the slot can be seen in FIG. 11. Each wing section 120 projects outwardly from an inner edge 122 of the main body section. As illustrated, the length of the wing section is sufficient to project completely through the slot when the lock members are in the position shown in FIG. 11, that is, when the curtain is experiencing normal stress conditions. The lock member 100 has two opposite end sections 124, 126 which taper longitudinally outwardly and in the direction of the inner surface of the lock member. This further facilitates the easy sliding movement of the lock member in the door guide. Each end section 124,126 can be formed with a rounded end at 128. A second form of lock member 150 is illustrated by itself in FIGS. 15 and 16, while FIG. 17 illustrates how a pair of these curtain lock members are arranged for attachment to opposite sides of a curtain (not shown). Except for the differences noted hereinafter, it will be understood that the lock member 150 is substantially the same in its construction to the lock member 100 shown in FIGS. 6 and 7. The lock member 150 has an elongate, main body section 152 having three curved or rounded, longitudinally extending surfaces at 154,156 and 158. As with the first embodiment, the lock member 150 is mounted so that its longitudinal axis is substantially parallel to the adjacent side edge 58 of the curtain. Each of the curved surfaces 154,158 forms a longitudinal side of the main body section. The lock member also has an inner surface 160 which is substantially flat and thus is adapted for mounting to a front or rear surface of the curtain. Unlike the lock member 100, the lock member 150 has no protrusion 118 projecting from the inner surface. As in the first embodiment, a pair of the lock members 150 can be mechanically attached to opposite sides of the curtain by means of two machine screws 110 that extend through two holes 162. Counterbores 114, 116 are also formed in the lock member 150. This embodiment also has a pair of flat wing sections 120 integrally connected to the main body section and extending from opposite sides thereof. A further difference in the construction of the two lock members is the shape of the opposite end sections formed on each lock member. The lock member 150 has opposite end sections 170, 172 and these are substantially shorter than the end sections 124, 126 of the lock member 100. Each end section is formed with a rounded end wall 174 and a sloping side 176. Thus, the end sections 170, 172 also taper longitudinally outwardly and in the direction of the inner surface of the lock member. The shape of the end sections 170, 172 also facilitates the easy sliding movement of the lock member in the door guide. In the preferred case where the wing sections are provided on the lock members, the combined thickness T of two wing sections of the pair of lock members and the curtain material should be less than the width of the elongate slot 68 in the normal, relaxed state of the guide. This thickness T is indicated in FIG. 11. With reference again to FIG. 5, this figure illustrates how the pairs of lock members 100 are longitudinally spaced along the vertical edges of-the curtain and they are preferably in close proximity to the curtain edge 58. Most of the lock pairs along each edge can be vertically aligned as shown. However, in the illustrated curtain of FIG. 5, near the bottom edge of the curtain, there can be one or two sets of curtain lock pairs 132. As illustrated in FIG. 5 and 9, there are two of these pairs 132 at each end of the bottom bar 20. If desired, these lock pairs 132 can be slightly offset from the vertical axis formed by the vertical alignment of the lock pairs located above the bottom bar. Although the lock pairs 132 are still located within the respective guide members 28, because of the offset, they cooperate with the bottom bar 20 to provide lateral stability to the lower portion of the curtain and the bottom bar. FIGS. 10 and 11 illustrate the functional relationship between one of the guide members 28, the curtain 12 and a pair of curtain lock members 100 during normal external force bias such as normal windloading on the curtain 12. The curved, two directional arrow B, is indicative of the normal dynamic force that acts on the central area of the curtain to cause a bellowing action. This action draws the pairs of curtain locks 100 into the split socket receptacle of the guide members 28. Because of the exterior curvature of the lock members and the concave interior surfaces 94 formed on the ribs, the lock members 100 can pivot in a “ball joint” fashion to accommodate the dynamic fluctuations and the changes in the position of the curtain 12. This ball joint action is enhanced by matching the external curvature of each lock member 100 to the concave curvature of the elongate interior surfaces 94. Note that by the provision of the wing sections that extend into the slot of the guide, these wing sections being made of low friction material, even though the lock members are in the position shown in FIG. 11, the curtain is still able to readily move upwardly or downwardly in its guide members because of the low friction at the contacting surfaces within the access slot 68. FIGS. 12 and 13 are cross-sectional details illustrating what occurs amongst the door guide, the curtain 12 and the curtain locks when an extreme dynamic force, such as that caused by vehicular impact on the curtain, is pulling on the curtain. This extreme force or bias pulls not only inwardly on each curtain edge section but also pulls the central area of the curtain either inwardly or outwardly of the door opening as indicated by the curved double pointed arrow C. This extreme force on the curtain and its edge section is evenly distributed to the symmetrical wall sections 62, 64 and their respective ribs 66 due to the symmetrical “ball joint” connection formed where the lock members engage the concave surfaces of the ribs. This results in even deflection of each wall section until the pair or pairs of lock members 100 are able to pass through the slot of the guide member 28. At this time, the curtain 12 is at least partially disengaged from one or both of the guide members 28, thereby avoiding undue damage to the door components. It should be noted that the relative position and size of the guide members, the curtain and the lock pairs are such that the lock pairs are normally spaced from each guide member's split socket receptacle when no external force bias is acting on the curtain (as shown in FIG. 3). However, the lock pairs are engaged with the guide member's split socket receptacle when a normal external force bias, such as windloading, is acting on the curtain 12 (as shown in FIGS. 10 and 11). It will be appreciated that each curtain lock pair has a curved exterior which is the inverse of the curved split socket formed by each guide member so that each lock pair can pivot in the described ball joint fashion within its guide member and it can self-adjust to accommodate the dynamic fluctuations in the curtain's position. Moreover, using the described preferred door components, including the guide members and the curtain locks, the door guide and curtain lock combination described herein can be made so that it is reliable and durable and able to provide long door life with long term repeatability of the release of the door edge sections as a result of a predetermined disengagement force. Also, because of the symmetry of the door guides and the curtain lock pairs, the edge sections of the door will reliably disengage from the guide members under a predetermined disengagement force even when there is directional preference of the external force bias. A variation of the door curtain 12 that comprises a further aspect of the present invention is illustrated in FIGS. 19 and 20. This door curtain can also be made of such flexible materials as rubber, synthetic rubber or fabric and the curtain is of course sized to close a selected doorway. As in -the curtain already described above, the curtain 12′ has front and rear surfaces, an upper end which is normally attached to a barrel, a lower end indicated at 180 and two opposite side edges. Only one of these side edges 182 is shown in FIGS. 19 and 20. In the curtain 12′, strips of low friction, wear-resistant material indicated generally at 184 are applied to at least one of the front and rear surfaces adjacent the opposite side edges of the curtain and are preferably affixed to both the front and rear surfaces as shown in FIG. 20. One wear resistant material that can be used is oliphatic polyetherurethane in dichlormethane (OPD). This wear-resistant material is sold under Product No. NR-7S by Normac Adhesive Products Inc. of Burlington, Ontario, Canada. This material can be applied in two different ways to the edge sections of the curtain 12′. Firstly, a glue strip, preferably comprising the rubber adhesive sold under Product No. XL-2000 is applied to the curtain edge sections where the OPD is to be applied and allowed to dry. Secondly, the OPD is brushed or sprayed on both sides of the curtain edge section over the glue strips and allowed to dry. Alternatively, the OPD strips can be made separately by spraying OPD onto a thin rubber adhesive layer 186 and then after the materials have dried thoroughly, the combined layers are bonded onto each curtain edge section and a rubber adhesive can also be used for this purpose. The preferred rubber adhesive material which forms the base coat 186 is that sold under Product No. XL-2000 by Normac Adhesive Products Inc. Although the combined thickness of the base coat 186 and the OPD can vary, in one preferred embodiment, it is about {fraction (1/16)}th inch thick on average with the thickness of the glue layer being only about 0.015 inch thick. XL-2000 adhesive is used to bond the base coat 186 to the adjacent surface of the curtain 12′. Preferably, the strips of wear-resistant material 184 are continuous strips along each edge section and they extend substantially the entire length of the curtain 12′. An alternative wear resistant material that can be used for the strips 184 is polyethyleneterepthalate (PET) polyester with a polyvinylchloride (PVC) backing. This material is available from Sampla Belting Canada Ltd. in Milton, Ontario, Canada and is sold under product number XX3AS. This material can be bonded to the curtain edges with a rubber adhesive in the same manner as the above described pre-fabricated OPD strips. As can be seen from FIGS. 19 and 20, the spaced apart pairs of curtain lock members 150 are mounted on and distributed along the side edge sections of the curtain 12′ and these lock members 150 are positioned on and applied to the strips of material 184. It will be appreciated that the advantages obtained with the low friction, wear-resistant strips 184 include reducing the amount of friction between the side edge sections of the curtain and the door guides (and thus-the amount of power required to operate the roll-up curtain) and reducing the amount of wear and tear on both the curtain edge sections and on the guides themselves. A preferred form of lock member 190 is illustrated in FIGS. 21 and 22. This lock member 190 is substantially the same as the lock member 150 illustrated in FIGS. 15 to 17 except for the addition of six tapered pins 192. These six pins are visible in FIG. 22 which shows the bottom surface 194 of the lock member. The pins 192, which are relatively short, are adapted to project into the adjacent side edge section of the door curtain in order to assist in holding the curtain lock member in place on the curtain during use of the door assembly. The pins are distributed over the bottom surface 194 with three pins being located around one of the holes 162 and another three pins located around the other hole 162. It will be appreciated that the pins 192 assist the mechanical fasteners ie. the machine screws 110, in preventing of the shearing of the curtain locks from the curtain during use of the door curtain, for example, when it is struck by a vehicle. In one preferred embodiment, each pin 192 measures about 0.144 inch in diameter at its base and tapers down to 0.072 inch in diameter at its end 198. This preferred pin has a height of 0.10 inch. It will be appreciated that when the curtain is made of a flexible material such as rubber or synthetic rubber, the pins can press into the flexible material and form their own indentation to provide a good grip between the bottom surface of the lock member and the curtain. From the above description of preferred embodiments, it will be seen that the present invention provides a curtain and door guide combination which is an improvement over prior art roll-up door constructions. The described, preferred curtain construction and door guides are able to cooperate in a “ball joint” fashion so that they can dynamically self-adjust at rest or during motion and evenly distribute the external force between the inner and outer wall sections of each guide member. The described roll-up type door remains functional and free moving with minimal frictional effect even during normal external force bias to the curtain such as windloading. In the preferred roll-up door construction described herein, pairs of curtain locks can be provided along each vertical edge of the curtain so that there is plenty of contact area between the lock members and each guide member to facilitate force dissipation, thereby reducing wear. It will be readily apparent to those skilled in the construction and operation of roll-up type doors that various modifications and changes can be made to the described and illustrated roll-up type door, door guides and curtain locks without departing from the spirit and scope of this invention. Accordingly, all such variations and modifications as fall within the scope of the appended claims are intended to be part of this invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>This invention relates to roll-up type door assemblies which are generally used in commercial and industrial applications, elongate guides for use in these door assemblies, and curtain locks for retaining edge sections of the flexible door curtains used in these door assemblies. It is well known in the door industry to provide a flexible, roll-up door that can be used to provide a passageway barrier in industrial, commercial, mining and other such facilities to accommodate the access of trucks, trains, forklifts and other such equipment to the facility or building or to provide passageway barriers within the facility or building. A flexible roll-up door typically consists of a synthetic rubber or fabric curtain which acts as a barrier across the passageway. The curtain is attached across its top edge to a rigid steel pipe spanning the width of the passageway. This steel pipe is typically known as a drive barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flanged type bearing attached to a steel plate, typically known as an endplate, which is attached to the, building structure directly above the passageway. Applying a controlled rotational movement of the drive barrel results in the curtain spooling onto the drive barrel, thus retracting the curtain upward to expose the passageway. Also, it may be inversely spooled off the drive barrel to dispense the curtain downward and close off the passageway. The lower, horizontal perimeter or bottom of the curtain is reinforced with structural steel members to provide rigidity to the section of curtain edge making contact with the ground. This component of a flexible roll-up door is typically known as a bottom bar and must be of sufficient rigidity to maintain adequate straightness of the curtain for the operation of the door. The bottom bar is configured to a predetermined mass to provide adequate gravitational force to pull the curtain to the ground. The bottom bar may include reversing, safety and/or sealing devices mounted thereon. The two vertical perimeters or edge sections of the curtain usually travel within suitable enclosures mounted adjacent to the passageway on each side. This component is typically known as a guide and serves the purpose of maintaining the required position of the vertical edge of the curtain while permitting unrestricted travel during door operation. The curtain is most often configured along its vertical edges with appropriate components, hereto referred to as curtain locks, to mate with the guides. Many flexible roll-up doors are constructed so that a predetermined releasing force can-cause the curtain to disengage itself from the guide or guides, for example, when the curtain is impacted by a vehicle or other device. The curtain is both retracted by and dispensed from the drive barrel over the forward side of a horizontal, rigid steel pipe spanning the width of the passageway. This pipe is located above the passageway and in close proximity to the building structure to provide an upper horizontal perimeter seal to the passageway and further serves as a curtain positioning mechanism, aligning the curtain with the guides mounted to the vertical sides of the passageway. This steel pipe is typically known as an idler barrel and is equipped with a solid steel shaft at both ends. Each of the two steel shafts are supported by a flange type bearing attached to its respective mounting angle. The known flexible roll-up door systems can also include various other components to complete their functionality such as a counterbalance system, often through the use of torsion springs and/or weights, an operating mechanism that may consist of a manual hoist and/or electric motor with gear and/or chain power transmission arrangement, along with other secondary components. Known roll-up doors are commonly equipped with a curtain that has an element or elements attached to the vertical edges of the curtain (forming a curtain lock or locks) that co-operate with fabricated, often elaborate, guide assemblies. U.S. Pat. No. 5,392,836 which issued Feb. 28, 1995 to Rite Hite Corporation teaches the use of a series of hemispherical follower elements attached to side edge sections of the curtain of a roll-up type door. An external force can disengage these follower elements from the door guide by changing the relative dimension of the gap formed by the guide and the follower element or elements. This relative dimensional change is achieved by utilizing a multiple component, fabricated guide that is inherently incapable of precise production dimensioning and often becomes askew or out of alignment during service. Thus, it is believed that this known roll-up door system is incapable of precise operation and therefore lacks reliability. U.S. Pat. No. 5,482,104 issued Jan. 9, 1996 to Dale Lichy also describes a multi-component guide assembly which an external force, such as an impact from a vehicle, can disassemble to provide disengagement of an edge section of the curtain from its respective guide assembly. In one embodiment, each side edge of the curtain is provided with a lock strip which is bonded to one surface of the side edge. The strip is relatively narrow in width and has a thickness about the same as that of the curtain. In a second version of the curtain, there is a lock strip on the outer surface of the curtain edge and a further lock strip on the inner surface so that the strips form double wind locks. The two strips are not aligned with each other with the strip on the outer surface being spaced laterally inwardly from the edge of the curtain and the other strip having its outer edge generally aligned with the side edge of the curtain. It is an object of one aspect of the present invention to provide a novel roll-up type door assembly having a flexible curtain made of rubber, synthetic rubber or fabric material employing extruded guide members that are relatively easy to manufacture and install and that can be made at a reasonable cost and employing pairs of curtain lock members mounted on the side edge sections of the curtain which help hold the side edge sections of the curtain in the guide members. It is an object of another aspect of the present invention to provide an elongate guide for use with a roll-up type door which can be manufactured relatively easily using known manufacturing techniques and at a reasonable cost and which is capable of engaging a curtain lock mechanism with interior concave surfaces in a manner so that the guide is capable of engaging the lock mechanism on both front and back sides of the curtain simultaneously. It is an object of an additional aspect of this invention to provide an improved and novel door curtain lock for retaining an edge section of a flexible door curtain in a door guide, this lock being made of low friction, wear resistant plastics material and having a rounded exterior surface and an inner surface for mounting to a front or rear surface of the door curtain. | <SOH> SUMMARY OF THE INVENTION <EOH>According to one aspect of the invention, a roll-up type door assembly includes a flexible curtain made of rubber, synthetic rubber or fabric material and capable of closing a doorway, this curtain having upper and lower ends and two opposite side edges. There is also a curtain winding mechanism having the upper end of the curtain attached thereto for raising the curtain by rolling the curtain up. The assembly also has two straight, extruded guide members which are made of flexible metal and, during use of the door assembly, are mounted so as to extend vertically on opposite, vertical sides of the doorway. Side edge sections of the curtain are each movable in a respective one of the guide members when the curtain is raised or lowered during use thereof. Each guide member is formed with integrally connected, inner and outer, longitudinally extending wall sections. Each wall section has an inwardly projecting, longitudinally extending rib with the two ribs of each guide member forming an elongate slot through which a respective one of the side edge sections can extend during use of the door assembly. Spaced-apart pairs of curtain lock members are mounted on and distributed along each side edge section of the curtain. The lock members of each pair are positioned opposite one another on front and rear surfaces of the curtain respectively. The combined thickness of each pair of lock members and the curtain material exceeds the width of the elongate slot so that the pairs of lock members prevent the side edge sections of the curtain from escaping out of the guide members under normal wind load or pressure conditions. At least some curtain lock members engage with the ribs of the respective guide members when an excessive wind load or impact is put upon the curtain and this engagement causes the arm sections of at least one guide member to separate from each other and thereby release the respective side edge section from the at least one guide member with little, if any, damage to the curtain or the guide members. Preferably, each curtain lock member is made of low friction, wear resistant plastics material and has an elongate main body section having a rounded exterior surface as seen from an end of the lock member. This lock member is mounted on its side edge section of the curtain so that its longitudinal axis is substantially parallel to the adjacent side edge of the curtain. According to another aspect of the invention, an elongate guide for use with a roll-up type door equipped with curtain lock mechanisms arranged along two opposite side edge sections of a flexible curtain for the door includes an elongate, metal guide member having inner and outer, longitudinally extending, substantially planar wall sections with a cavity formed between these wall sections. This cavity is adapted to slidably receive one of the side edge sections. The guide member also has a base section integrally connected to and joining the inner and outer wall sections and two, longitudinally extending metal ribs each integrally formed on a respective one of the inner and outer wall sections and together defining one end of the cavity as seen in transverse cross-section. The two ribs project inwardly towards each other and form an elongate slot which is substantially narrower than the maximum width of the cavity as measured between the two wall sections and through which a respective one of the side edge sections can extend during use of the guide. Each rib has an elongate interior surface which is concave as seen in transverse cross-section and the concave surfaces of the two ribs form an elongate split curved socket for directly engaging the curtain lock mechanism when the lock mechanism is located in the guide during use thereof. The split curved socket is capable of engaging the lock mechanism on both front and back sides of the curtain simultaneously. The preferred guide member is an integral, one-piece metal extrusion and the preferred metal is aluminum alloy. According to another aspect of the invention, a door curtain lock for retaining an edge section of a flexible door curtain in an elongate door guide mounted on a side of a doorway includes a lock member made of low friction, wear resistant plastics material. This lock member has an elongate, rigid main body section having exterior surface which is rounded as viewed from one end of the lock member. The rounded exterior surface extends to at least one longitudinal side of the main body section. The lock member also has an inner surface adapted for mounting to a front or rear surface of the door curtain. Also, at least one hole for a mechanical fastener is found in the main body section. Preferably the lock member has a substantially flat wing section integrally connected to one longitudinal side of the main body section and adapted to extend through an elongate slot formed in the door guide during use of the curtain lock. This wing section projects outwardly from an inner edge of the main body section. According to yet another aspect of the invention, a door curtain for use in a roll-up door apparatus comprises a flexible curtain made of rubber, synthetic rubber or fabric and capable of closing a doorway. The curtain has front and rear surfaces, upper and lower ends and two opposite side edges. Strips of low friction, wear-resistant material are affixed to at least one of the front and rear surfaces adjacent the opposite side edges, the wear-resistant material selected from the group consisting of oliphatic polyetherurethane in dichlormethane (OPD) and polyethylene terepthalate (PET) polyester with a polyvinylchloride (PVC) backing. A plurality of curtain lock members are mounted on and distributed along the strips of wear-resistant material, these lock members being spaced apart from one another. Further features and advantages will become apparent from the following detailed description taken in conjunction with the accompanying drawings. | 20040331 | 20090414 | 20050113 | 73100.0 | 2 | BRADFORD, CANDACE L | ROLL-UP FLEXIBLE DOOR AND GUIDES THEREFOR | SMALL | 0 | ACCEPTED | 2,004 |
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10,813,772 | ACCEPTED | Ink jet recording paper | A thermal ink jet recording paper, incorporating dewatered and milled precipitated calcium carbonate (“PCC”) is disclosed. Precipitated calcium carbonate is dewatered and milled in the presence of an amphoteric or anionic dispersant to produce a high solids PCC composition. When used in coating formulations the PCC has a surface morphology and chemistry that enhances the printability of ink jet paper. Ink jet recording paper incorporating the PCC of the present invention has reduced ink feathering and spreading as well as improved optical density, dry time, and water fastness. | 1. A method for producing a precipitated calcium carbonate for ink jet recording paper comprising: a) Admixing calcium oxide with water to produce a calcium hydroxide slurry; b) admixing a first amount of an organophosphonate followed by adding aluminum sulfate to the calcium hydroxide slurry; c) introducing carbon dioxide to the calcium hydroxide slurry to produce a precipitated calcium carbonate slurry; d) adding a second amount of organophosphonate to the precipitated calcium carbonate slurry; e) admixing phosphoric acid to the precipitated calcium carbonate slurry; f) screening and dewatering the calcium carbonate slurry; and g) milling the precipitated calcium carbonate in the presence of an amphoteric or anionic dispersant to produce a precipitated calcium carbonate product. 2. The method of claim 1 wherein the first organophosphonate is selected from the group consisting of nitrilo-tris-(methylene phosphonic acid), ethylenediaminetetra (methylene phosphonic acid), diethylenetriaminepenta (methylene phosphonic acid), hydroxy ethane-1,1-diphosphonic acid, ethanolamine, ethanolamine bis-(methylenephosphonic acid), N-dimethylene phosphonic acid, and hexamethylenediaminetetra (methylene phosphonic acid). 3. The method of claim 2 wherein the first amount of the organophosphonate is employed at a level of from about 0.04 percent by weight calcium hydroxide slurry to about 0.15 percent by weight calcium hydroxide slurry and wherein the aluminum sulfate is from about 2.5 percent by weight calcium hydroxide slurry to about 4.5 percent by weight calcium hydroxide slurry. 4. The method of claim 3 wherein the first organophosphonate is ethanolamine bis-(methylenephosphonic acid). 5. The method of claim 1 wherein the second organophosphonate is employed at a level of from about 0.50 percent weight PCC slurry to about 1.0 percent weight PCC slurry. 6. The method of claim 5 wherein the second organophosphonate is ethanolamine bis-(methylenephosphonic acid). 7. The method of claim 1 wherein the amphoteric dispersant is selected from the group consisting of sodium salts of co-polymers of acrylic acid and diallyldimethylammonium chloride (DMDAAC), sodium salts of co-polymers of acrylic acid and methyl chloride quaternaryamine of dimethylaminoethylacrylate (DMAEA:quatemaryamine) and acrylic acid (AA)-DMDAAC:quaternaryamine copolymer. 8. The method of claim 7 wherein the amphoteric dispersant is employed at a level of from about 1.0 percent active dispersant by weight PCC to about 5.0 percent active dispersant by weight PCC. 9. The method of claim 8 wherein the amphoteric dispersant has a molecular weight ranging from about 2000 to about 10000. 10. The method of claim 1 wherein the anionic dispersant is from the group consisting of sodium polyacrylates and copolymers of acrylic maleic acids. 11. The method of claim 10 wherein the anionic dispersant is employed at a level of from about 1.0 percent active dispersant by weight PCC to about 5.0 percent active dispersant by weight PCC. 12. The method of claim 11 wherein the anionic dispersant has a molecular weight ranging from about 2000 to about 10000. 13. The method of claim 1 wherein the PCC produced is from about 25 percent solids to about 65 percent solids concentration viscosity of from about 500 centipoise to about 1000 centipoise specific surface area of from about 60 m2/g to about 100 m2/g and surface charge of from about −(negative) 30 millivolt (mV) to about +5 mV. 14. A coating formulation for ink jet recording paper comprising: PCC produced from about 25 percent solids to about 65 percent solids concentration viscosity from about 500 centipoise to about 1000 centipoise specific surface area from about 60 m2/g to about 100 m2/g and surface charge from about −(negative) 30 millivolt (mV) to about +5 mV and a binder. 15. The coating formulation of claim 14 wherein the binder is selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, oxidized starch, esterified starch, dextrin, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soybean protein, maleic anhydride resin, styrenebutadiene copolymer, methyl methacrylate-butadiene copolymer, acrylate and methacrylate polymers. 16. An ink jet recording paper comprising a paper base stock, having a coating comprising: a milled precipitated calcium carbonate pigment, the pigment being produced by milling a precipitated calcium carbonate in the presence of an amphoteric or anionic dispersant wherein the milled precipitated calcium carbonate has a solids concentration from about 25 percent by weight to about 65 percent by weight concentration solids and a viscosity of from about 200 centipoise to about 2000 centipoise and a specific surface area from about 60 m2/g to about 100 m2/g. 17. A method for producing a precipitated calcium carbonate for ink jet recording paper comprising: a) Admixing calcium oxide with water to produce a calcium hydroxide slurry; b) admixing a first amount of an organophosphonate followed by adding aluminum sulfate to the calcium hydroxide slurry; c) introducing carbon dioxide to the calcium hydroxide slurry to produce a precipitated calcium carbonate slurry; d) adding a second amount of organophosphonate to the precipitated calcium carbonate slurry; e) admixing phosphoric acid to the precipitated calcium carbonate slurry; f) screening and dewatering the calcium carbonate slurry; g) milling the precipitated calcium carbonate in the presence of an amphoteric or anionic dispersant to produce a precipitated calcium carbonate product; and, h) coating at least one side of a paper base stock with a coating formulation comprising the milled precipitated calcium carbonate and binder to form the ink jet recording paper. 18. A method according to claim 1 wherein the milled PCC is used in ink jet coating formulations for paperboard transparency, fabric, and tee-shirt iron-ons. | FIELD OF THE INVENTION The present invention relates to milled precipitated calcium carbonate (PCC) pigments for use in ink jet recording paper. More particularly, the present invention relates to an ink jet recording paper which incorporates such pigments to impart enhanced print quality. The invention further relates to methods of producing milled PCC and to the application of the milled PCC to ink jet recording paper. BACKGROUND OF THE INVENTION The thermal ink jet process applies a dilute aqueous ink onto the surface of a paper by heating a small volume of the ink in a small chamber with an orifice that is directed at the recording paper. The small volume of ink that is heated rapidly reaches its boiling point, and the steam bubble formed propels a tiny drop of liquid ink at the paper, where the drop produces a single dot in a dot matrix that forms a character or image on the sheet. This process requires an ink that is low in solids and high boiling components so that it is capable of boiling rapidly without leaving a residue that can foul the heating element, and clog the orifice. Therefore, up to ninety-six (96) percent by weight of ink jet printer ink is a mixture of water and low molecular weight glycols. Although such an ink boils quickly when heated to ensure rapid printing, and is not prone to clog, it results in an applied ink that is very mobile and slow to dry. Therefore, good print quality can be obtained only if the ink colorant or dye remains on or near the outer surface of the paper, and does not spread or move from the point at which it was applied. It is also important that drying occurs rapidly to prevent smearing of the colorant. In printers that are not equipped with heating elements, the water and glycol components of the ink must penetrate into the body of the paper for proper drying of the colorant on the surface. If the colored phase is carried into the paper with the liquid phase as it penetrates into the paper, or if the colorant migrates across the surface of the paper, the quality of the resulting print or image will be poor. Also, dry ink colorant that is not permanently fixed on the paper will blot or run if the printed surface becomes wet or is marked with a highlighter. Therefore, the dry ink should have excellent water and highlighter fastness properties for optimum performance. In most applications, multipurpose office papers provide inadequate or poor thermal ink jet print quality. This is particularly true where multicolor printing with concomitant superimposed ink applications is utilized. The poor print quality is compounded in printers that apply the colors in one order when the print head moves to the right and the reverse order when the print head moves to the left. Multipurpose office papers often allow the colorant to penetrate into the paper, which results in reduced optical density of the printed image, and increased show through on the reverse side of the paper. Multipurpose office papers that are highly sized prevent liquid penetration, leading to higher ink optical density, but, also, excessive feathering and spreading. One method of improving thermal ink jet print quality is to apply a material to the paper surface that binds the ink colorant to the surface, but allows the water/glycol liquid phase to pass into the body of the paper, which speeds drying. However, the ink colorant often is an unsaturated or aromatic organic compound, and if the surface material interacts too strongly with the colorant the color of the ink can change. Therefore, a surface material is sought that prevents the ink colorant from penetrating the paper, but does not interact so strongly as to effect the colorant, and cause a color change. Other methods have used cationically charged pigments where it was thought these would be more interactive with ink jet dyes. However, these are generally low in solids, ten (10) to twenty (20) percent, and therefore there are application limitations, such as decreased production rates and lower coater speeds, due to the low solids concentration. The present invention provides one solution to the problems associated with ink jet printing. SUMMARY OF THE INVENTION The present invention provides for an ink jet recording paper that incorporates milled precipitated calcium carbonate (PCC). The milled PCC is prepared by adding a first amount of an organophosphonate compound to calcium hydroxide slurry followed by admixing an aluminum sulfate to the calcium hydroxide slurry. Carbonating the calcium hydroxide slurry to produce PCC slurry. Admixing a second amount of organophosphonate to the PCC slurry. The PCC slurry is then dewatered and treated with an amphoteric or anionic dispersant followed by milling the PCC slurry. DETAILED DESCRIPTION OF THE INVENTION An ink jet recording paper has been produced that provides full color ink jet print quality. The selection of precipitated calcium carbonate (PCC) particle size, surface area, surface chemistry, and degree of aggregation allows each thermal ink jet print characteristic to be individually adjusted and optimized. The PCC for ink jet recording paper of the present invention is produced wherein calcium oxide is admixed with water to produce a calcium hydroxide slurry. To the calcium hydroxide slurry a first amount of an organophosphonate is added. The calcium hydroxide slurry is then admixed with aluminum sulfate prior to introducing carbon dioxide into the calcium hydroxide slurry. Thus converting the calcium hydroxide to precipitated calcium carbonate (PCC). A second amount of organophosphonate is then added to the PCC slurry followed by screening and dewatering the PCC slurry forming a concentrated PCC composition. An amphoteric or anionic dispersant is then added to the concentrated PCC composition which is milled producing the milled PCC composition for use in ink jet coating formulations. PCC Preparation Admix calcium oxide with water to produce a calcium hydroxide slurry. Adjust the calcium hydroxide slurry temperature from about 65 degrees Celsius to about 75 degrees Celsius to about 10 degrees Celsius to about 14 degrees Celsius. Admix from about 0.04 percent by weight to about 0.15 percent by weight calcium hydroxide of an organophosphonate to the calcium hydroxide slurry. Admix from about 2.5 percent to about 4.5 percent by weight calcium hydroxide an aluminum sulfate to the calcium hydroxide slurry. Reduce the temperature of the calcium hydroxide slurry from about 10 degrees Celsius to about 14 degrees Celsius to about 6 degrees Celsius to about 7 degrees Celsius. Add carbon dioxide to the calcium hydroxide slurry until the calcium hydroxide slurry is converted to calcium carbonate (PCC) slurry. Admix from about 0.5 percent by weight PCC to about 1.5 percent by weight PCC an organophosphonate with the precipitated calcium carbonate (PCC) slurry. A phosphoric acid is added at a concentration of from about 0.2 by weight PCC to about 0.5 by weight PCC to the PCC slurry to stabilize and maintain the surface area of the PCC product. The PCC slurry is then screened and dewatered to from about 25 percent to about 65 percent by weight PCC to produce a concentrated PCC composition. The PCC composition is admixed with from about 1.0 percent active dispersant by weight PCC to about 5.0 percent active dispersant by weight PCC of an amphoteric or anionic dispersant prior to being milled. To obtain the desired application viscosity, the dispersant level may exceed upwards of from about 8.0 percent active dispersant by weight PCC to about 10.0 percent active dispersant by weight PCC. The PCC produced according to the present invention has a surface area of from about 60 meters squared per gram (m2/g) to about 100 m2/g and a solids concentration of about 10 percent by weight PCC. After the completion of carbonation a second amount of organophosphonate in an amount of from about 0.60 percent by weight PCC to about 0.75 percent by weight PCC is added to the PCC slurry and agitated to a pH of from about 7.0 to about 8.0. The PCC slurry is then screened, dewatered and milled in the presence of a dispersant to obtain the milled PCC having the characteristics of the present invention's high-quality, low cost ink jet recording paper. Dewatering can be carried out using technology known in the art to include, but not limited to, centrifugation, filter press such as plate and frame press, Larox press, Andritz press, belt press, tube press, vacuum, or other known dewatering technology. Milling of the PCC may be carried out in either a wet or dry milling process, for example, a conventional ball mill, jet mill, micro mill, Cowles type dispersion mixer, kady mill, impingement type mill, sand or media mill. Milling can be carried out by introducing concentrated slurry of PCC into a media mill containing glass media of a size from about 0.7 mm to about 0.9 mm. The media mill is equipped with mechanical agitation, and the resulting weight percent solids of the PCC slurry is from about 25 to about 65 percent based on the total weight of the PCC and the water. When media milling is performed on the PCC of the present invention, the specific surface area is from about 50 meters squared per gram (m 2/g) to about 120 m2/g, or from about 60 m2/g to about 100 m2/g. Milling is performed on the PCC of the present invention to a target Brookfield viscosity of from about 200 centipoise (cps) to about 2000 cps at 100 revolutions per minute (rpm) using the appropriate spindle. The Organophosphonates The organophosphonates employed in the present invention are organopolyphosphonates of varying molecular weights commonly used as scale inhibitors, sequesterants, dispersants, deflocculants, and detergent promoters. Such organophosphonates include, but are not limited to, nitrilo-tris-(methylene phosphonic acid), ethylenediaminetetra (methylene phosphonic acid), diethylenetriaminepenta (methylene phosphonic acid), hydroxy ethane-1, 1-diphosphonic acid, ethanolamine, ethanolamine bis-(methylenephosphonic acid), N-dimethylene phosphonic acid, and hexamethylenediaminetetra (methylene phosphonic acid). A useful organophosphonate is ethanolamine bis-(methylenephosphonic acid). The organophosphonates that are useful in the present invention can be any organophosphonates that are known and available in the art. When the first organophosphonate is admixed with the calcium hydroxide slurry, the range is from about 0.04 percent by weight calcium hydroxide slurry to about 0.15 percent by weight calcium hydroxide slurry, or from about 0.08 percent by weight calcium hydroxide slurry to about 0.12 percent by weight calcium hydroxide. When the second organophosphonate is admixed with the PCC slurry, the range is from about 0.50 percent weight PCC slurry to about 1.0 percent weight PCC slurry, or from about 0.60 percent by weight PCC slurry to about 0.75 percent by weight PCC slurry. The Aluminum Sulfate The aluminum sulfate can be any aluminum sulfate known and available in the art. When the aluminum sulfate is admixed with the calcium hydroxide slurry, the range is from about 2.5 percent by weight calcium hydroxide slurry to about 4.5 percent by weight calcium hydroxide slurry or from about 2.8 percent by weight calcium hydroxide slurry to about 4.0 percent by weight calcium hydroxide slurry. The process of the present invention to this point is essentially that of U.S. Pat. No. 4,367,207, U.S. Pat. No. 4,892,590, and U.S. Pat. No. 5,783,038, the teachings of which are incorporated herein by reference. The Amphoteric Dispersant The amphoteric dispersant of the present invention is selected from the group consisting of sodium salts of co-polymers of acrylic acid and diallyldimethylammonium chloride (DMDAAC). They may also be selected from the group consisting of sodium salts of co-polymers of acrylic acid and methyl chloride quaternaryamine of dimethylaminoethylacrylate (DMAEA: quaternaryamine). They may further be selected from the group consisting of an acrylic acid (AA) and an DMDAAC:quaternaryamine copolymer. The amphoteric dispersants useful in the present invention having a molecular weight ranging from about 2000 to about 10000 or from about 2000 to about 6000 as determined by intrinsic viscosity method. When the amphoteric dispersant is admixed with the PCC slurry, the range is from about 1.0 percent active dispersant by weight PCC to about 5.0 percent active dispersant by weight PCC or from about 2.0 percent active dispersant by weight PCC to about 3.5 percent active dispersant by weight PCC. The Anionic Dispersant The anionic dispersants useful in the present invention are selected from sodium polyacrylates having a molecular weight ranging from about 2000 to about 10000 or from about 2000 to about 6000 as determined by intrinsic viscosity method. Some commercially available dispersants that work in the present invention include Colloids 207, 211, 220 and 260 from Kemira Chemicals, Inc. 245 Town Park Drive, Suite 200, Kennesaw, Ga. 30144; Acumer 9300 from Rohm & Haas Company 100 Independence Mall West, Philadelphia, Pa. 19106-2399; and Sokalan HP-80 from BASF Corporation Function Polymers, 11501 Steele Creek Rd., Charlotte, N.C. 28273. Also, the anionic dispersant can be a copolymer of acrylic and maleic acids. When the anionic dispersant is admixed with the PCC slurry, the range is from about 1.0 percent active dispersant by weight PCC to about 5.0 percent active dispersant by weight PCC or from about 2.0 percent active dispersant by weight PCC to about 3.5 percent active dispersant by weight PCC. In the present invention, screening of the PCC starts by ending the reaction of carbon dioxide and calcium hydroxide when the conductivity of the slurry reaches a minimum, which is typically at a pH of from about 7 to about 8. Organophosphonate at a concentration of up to about 1.5 percent by weight of PCC is added to control surface area of the final product. Other chemical agents that are surface active with regard to calcium carbonate will also serve as well as organophosphonates to control the surface area of the final product. Such agents include, but are not limited to the following, sodium polyphosphates, sodium silicates, sodium polyacrylates, various carboxylic acids, such as mono, di, tri and polycarboxylic acids, and their salts, various polysaccharides, and various gums with repeating carboxylic acid functionalities. Ink jet recording papers incorporating the PCC of the present invention have been prepared. The following is a summary of the procedures and testing methods used. Once the PCC of the present invention is produced, the entire testing process can be categorized into four areas; pigment preparation, formulation with binder, paper coating and processing, and testing. Specific details for each of these procedures are given below. Pigment Preparation Pigments to be tested are typically in the form of a slurry or a filter cake. Samples in the form of a slurry are concentrated to the desired solids by vacuum filtration. In some instances, such as with a media milled PCC with a specific surface area of about 60 m2/g to 100 m2/g, the slurry solids are not further altered in order to duplicate trial conditions. Once the target formulation solids is set, the pigment is diluted, if necessary, with water and thoroughly mixed. The pigment is characterized by specific surface area (Flowsorb), solids concentration, surface charge and viscosity (Brookfield). The surface area of the product was obtained by using a Micromeritics Flowsorb II 2300, which employs BET theory with nitrogen as the absorbing gas. Surface charge of the product was determined using Doppler Electrophoretic Light Scattering Analysis (DELSA). Coating Formulation Typical binders include starch, polyvinyl alcohol (PVOH), polyvinyl acetate and latex. These can be used as the sole binder or blended with other binders as is known in the art. When a starch is used as a binder, the dry starch is dispersed in water at from about 10 to about 35 percent solids, and then cooked in an automated laboratory cooker at about 195 degrees Celsius for about 50 minutes to about 190 minutes. The resulting viscous starch slurry is combined with the pigment, which has been appropriately prepared to attain the target coating formulation solids, and mixed thoroughly on a Premier mill with a Cowles type open impeller blade. The formulation is mixed for about 5 minutes until a completely homogenous slurry is obtained, and the resulting coating formulation is characterized by Brookfield viscosity (10, 20, 50 and 100 rpm) and solids. Dry polyvinyl alcohol is prepared in a manner similar to that used for starch. The PVOH is hydrated at about 200 degrees Celsius in a laboratory cooker for from about 50 minutes to about 190 minutes at about from 10 percent solids to about 25 percent solids. For the latex binder (50 percent solids), liquid PVOH or polyvinyl acetate, no preparation is necessary before testing. The formulation of these binders with the pigment is the same as with the starch. Coating formulation solids for the tests were in the range of from about 20 percent solids by weight to about 50 percent solids by weight, with a typical coating formulation having from about 30 percent solids by weight to about 45 percent solids by weight. Binders Examples of binders useful for coating compositions for ink jet recording paper are those heretofore conventionally used in the art, and include PVOH and derivatives thereof, oxidized starch, esterified starch, dextrin and like starches, carboxymethylcellulose, hydroxyethylcellulose and like cellulose derivatives, casein, gelatin, soybean protein, maleic anhydride resin, lattices of usual styrenebutadiene copolymer, methyl methacrylate-butadiene copolymer and like conjugated diene polymers or copolymers, and lattices or acrylate and methacrylate polymers or copolymers and like acrylic polymers, and latex. When required, the coating composition may have further incorporated therein in an amount conventionally used in the art of conventional pigment dispersants, tackifiers, flowability modifiers, defoaming agents, foaming inhibitors, release agents, coloring agents, and the like. Paper Coating Generally, an unsized base stock of about 81.3 grams per meter squared (g/m2) to about 83.0 g/m2 basis weight is used in the tests. The paper is cut into 12 inch×17 inch sheets and secured to the CSD Drawdown Apparatus, manufactured by CSD Tech International, Inc., of Oldsmar, Fla., which consists of a glass plate (12 inch×17 inch) mounted on metal base with spring clip at the top. A coating formulation is applied with a CSD drawdown rod by placing the rod of choice, which depends on target coat weight, at the top of the paper, adding a uniform line of coating formulation across the top of the paper, below the rod, and coating the paper by pulling the drawdown rod from top to bottom using light pressure and a constant, steady rate for about 2 seconds. The coat weight is determined by the stainless steel drawdown rods, which are specifically grooved to deliver a predetermined coating volume to the paper surface. Rods with fewer grooves deliver a heavier coat weight, since the spaces between the grooves is wider. In turn, rods with a greater number of more tightly spaced grooves produce lighter coat weights. Typical coat weights are from about 2 grams per meter squared (g/m2) to about 12 g/m2. Once a coating formulation has been applied, the paper is immediately dried with a hand held heat gun for from about 30 seconds to about 60 seconds, and then completely dried and conditioned in a constant temperature and humidity environment over a period of about 24 hours. The conditioned papers are then cut into 8½×11 inch sheets for testing. The coating formulation of the present invention can be applied to paper basestock using any paper coater known in the art such as a rod coater, blade coater, airknife, metersize press, size press, curtain coater or cast coater. Paper Testing Minimum ink jet print quality criteria have been established by Hewlett Packard Corporation (“HP”). Therefore, most tests utilize HP methods to determine the following print characteristics. Optical density is a measure of the reflection density of an image. A specific test pattern is printed onto the paper, and the optical densities of pure black, composite black, cyan, magenta, and yellow are measured using a reflection densitometer (Macbeth RD918). The resulting optical densities are compared to minimum HP specifications. Ink spreading and feathering can both decrease the quality of ink jet print. Ink spreading is defined as the growth or widening of printed areas. Feathering is the wicking of ink, which results in fuzzy images. This is measured by analyzing a specific portion of the same printed pattern used for optical density measurements. The specific portion is evaluated for ink area, spreading, and ink perimeters, feathering. The resulting, digitized pattern is quantitated and compared to a commercial premium ink jet paper. The HP test method for ink spreading and feathering was not used in these tests, since the HP test is subjective rather than quantitative. Ink Dry Time is a measure of the rate of ink absorption into a sheet of paper. A specific test pattern is printed, the image is blotted, and the resulting optical density of the transferred black ink is measured. The results are fitted to a decaying exponential model from HP, and the ink dry time is calculated. The final dry times are compared to minimum criteria set by HP. Waterfastness is a measure of the amount of colorant transferred from a printed area to an unprinted area when water is applied. The waterfastness test pattern is printed onto the paper, 250 microliter (μm) of water is applied across the print, and allowed to run over the printed area and adjacent unprinted area. The optical density of the transferred black ink on the unprinted areas is measured. Resulting optical densities are compared to HP standards. In the brightness test, the coated paper is tested for TAPPI brightness using the Technidyne S-4 brightness meters. Results are compared to the uncoated base stock. Other Ink Jet Media The present invention also relates to the use of the PCC pigment in ink jet coating formulations that are particularly useful in paperboard transparency, fabric, and tee-shirt iron-ons. The PCC for use in these applications is prepared according to the process of the present invention for the preparation of the ink jet coating formulation. EXAMPLES The following non-limiting examples are merely illustrative embodiments of the present invention and are not to be construed as limiting the invention, the scope of which is defined by the appended claims. Example 1 Calcium oxide with water was admixed in a portec slaker producing a calcium hydroxide slurry having a percent rapid slake of at least 90 percent as measured by methyl orange (MO) titration. The calcium hydroxide slurry was transferred to a reaction vessel and the temperature adjusted to about 12 degrees Celsius, at which time 0.12 percent by weight organophosphonate (Briquest 221-50A) was admixed with the calcium hydroxide slurry followed by 3.7 percent by weight aluminum sulfate. The temperature was lowered to 6.5 degrees Celsius. Carbon dioxide was added until conductivity reached a minimum, about 35 minutes, indicating the calcium hydroxide slurry had been converted to calcium carbonate slurry. Carbonation was continued for an additional 5 minutes before being shut off and the material agitated for an additional 10 minutes producing about a 10 percent solids PCC slurry with a pH of about 7.0 to about 8.0. At this point about 0.6 percent by weight organophosphonate (Briquest 221-50A) was added to the PCC slurry followed by 0.3 percent by weight PCC of phosphoric acid. The PCC slurry was screened at 325 mesh and dewatered through centrifugation. The PCC composition was treated with dispersant and then processed using a Kady mill to produce a dispersed PCC composition that is about 35 percent solids to about 45 percent solids concentration. The composition has a Brookfield viscosity of from about 500 centipoise to about 1000 centipoise as measured at 100 rpm with the appropriate spindle. The PCC particles have a specific surface area of from about 85 m2/g to about 100 m2/g and a surface charge of from about −(negative) 30 millivolt (mV) to about +5 mV dependant upon the dispersant chemistry employed. Example 2 Calcium carbonate was produced in the same manner as that described in Example 1. The milled PCC was evaluated in coating formulations using six amphoteric and/or anionic dispersants with an uncoated paper basestock. Each PCC composition was formulated into an ink jet coating with 7 parts polyvinyl alcohol per 100 parts PCC. Paper samples were coated with from about 5 g/m to about 7 g/m2. After drying, hand drawdowns were tested for optical density and color bleed evaluations. The results of these tests are given in Table 1. TABLE 1 Ink Spreading Black Cyan Magenta Yellow and (optical (optical (optical (optical Feathering density) density) density) density) Sample 100.518 1.52 1.40 1.31 1.28 1 99.974 1.60 1.39 1.28 1.24 2 101.083 1.44 1.51 1.41 1.28 3 100.744 1.39 1.42 1.27 1.26 4 101.212 1.44 1.50 1.41 1.28 5 101.059 1.42 1.52 1.39 1.29 6 104.600 1.36 1.17 1.16 1.11 *Control *uncoated basestock The present invention provides for lower ink spreading and feathering (lower numbers are better) while maintaining optical density when compared with an uncoated basestock. Example 3 Calcium carbonate was produced in the same manner as that described in Example 1. The milled precipitated calcium carbonate (PCC) was formulated into an ink jet coating and paper samples were coated with from about 5 g/m2 to about 7 g/m2 of the coating formulation. After drying, hand drawdowns were tested for optical density and color bleed evaluations. The results of these tests are given in Table 2. TABLE 2 Ink Spreading Black Cyan Magenta Yellow and (optical (optical (optical (optical Feathering density) density) density) density) Binder 101.84 1.41 1.48 1.39 1.27 Starch 30 100.974 1.67 1.56 1.38 1.24 PVOH 7 101.521 1.53 1.51 1.39 1.27 Starch 15 and PVOH 4 104.600 1.36 1.17 1.16 1.11 uncoated basestock The results indicate that a range of binders can be used with the PCC of the present invention to provide for lower ink spreading and feathering (lower numbers are better) while maintaining superior optical density to that of the uncoated basestock. While it is apparent that the invention disclosed herein is well calculated to fulfill the objects stated above, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art. Therefore, it is intended that the appended claims over all such modifications and embodiments fall within the scope of the present invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>The thermal ink jet process applies a dilute aqueous ink onto the surface of a paper by heating a small volume of the ink in a small chamber with an orifice that is directed at the recording paper. The small volume of ink that is heated rapidly reaches its boiling point, and the steam bubble formed propels a tiny drop of liquid ink at the paper, where the drop produces a single dot in a dot matrix that forms a character or image on the sheet. This process requires an ink that is low in solids and high boiling components so that it is capable of boiling rapidly without leaving a residue that can foul the heating element, and clog the orifice. Therefore, up to ninety-six (96) percent by weight of ink jet printer ink is a mixture of water and low molecular weight glycols. Although such an ink boils quickly when heated to ensure rapid printing, and is not prone to clog, it results in an applied ink that is very mobile and slow to dry. Therefore, good print quality can be obtained only if the ink colorant or dye remains on or near the outer surface of the paper, and does not spread or move from the point at which it was applied. It is also important that drying occurs rapidly to prevent smearing of the colorant. In printers that are not equipped with heating elements, the water and glycol components of the ink must penetrate into the body of the paper for proper drying of the colorant on the surface. If the colored phase is carried into the paper with the liquid phase as it penetrates into the paper, or if the colorant migrates across the surface of the paper, the quality of the resulting print or image will be poor. Also, dry ink colorant that is not permanently fixed on the paper will blot or run if the printed surface becomes wet or is marked with a highlighter. Therefore, the dry ink should have excellent water and highlighter fastness properties for optimum performance. In most applications, multipurpose office papers provide inadequate or poor thermal ink jet print quality. This is particularly true where multicolor printing with concomitant superimposed ink applications is utilized. The poor print quality is compounded in printers that apply the colors in one order when the print head moves to the right and the reverse order when the print head moves to the left. Multipurpose office papers often allow the colorant to penetrate into the paper, which results in reduced optical density of the printed image, and increased show through on the reverse side of the paper. Multipurpose office papers that are highly sized prevent liquid penetration, leading to higher ink optical density, but, also, excessive feathering and spreading. One method of improving thermal ink jet print quality is to apply a material to the paper surface that binds the ink colorant to the surface, but allows the water/glycol liquid phase to pass into the body of the paper, which speeds drying. However, the ink colorant often is an unsaturated or aromatic organic compound, and if the surface material interacts too strongly with the colorant the color of the ink can change. Therefore, a surface material is sought that prevents the ink colorant from penetrating the paper, but does not interact so strongly as to effect the colorant, and cause a color change. Other methods have used cationically charged pigments where it was thought these would be more interactive with ink jet dyes. However, these are generally low in solids, ten (10) to twenty (20) percent, and therefore there are application limitations, such as decreased production rates and lower coater speeds, due to the low solids concentration. The present invention provides one solution to the problems associated with ink jet printing. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides for an ink jet recording paper that incorporates milled precipitated calcium carbonate (PCC). The milled PCC is prepared by adding a first amount of an organophosphonate compound to calcium hydroxide slurry followed by admixing an aluminum sulfate to the calcium hydroxide slurry. Carbonating the calcium hydroxide slurry to produce PCC slurry. Admixing a second amount of organophosphonate to the PCC slurry. The PCC slurry is then dewatered and treated with an amphoteric or anionic dispersant followed by milling the PCC slurry. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20071204 | 20051006 | 76958.0 | 0 | FIORITO, JAMES A | INK JET RECORDING PAPER | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,784 | ACCEPTED | Back end IC wiring with improved electro-migration resistance | A multi-level semiconductor device wiring interconnect structure and method of forming the same to improve electrical properties and reliability of wiring interconnects including an electromigration resistance and electrical resistance, the method including forming a dielectric insulating layer over a conductive portion; forming a via opening in closed communication with the conductive portion; forming a first barrier layer to line the via opening; forming a layer of AlCu according to a sputtering process to fill the via opening to form an AlCu via including a portion overlying the first dielectric insulating layer; and, photolithographically patterning and dry etching the portion to form an AlCu interconnect line over the AlCu via. | 1. A method of forming a multi-level semiconductor device wiring interconnect structure comprising the steps of: a) forming a dielectric insulating layer over a conductive portion; b) forming a via opening in closed communication with the conductive portion; c) forming a barrier layer to line the via opening; d) forming a layer of AlCu to fill the via opening to form an AlCu via including a portion overlying the first dielectric insulating layer; and, e) forming the portion to form an AlCu interconnect line over the AlCu via. 2. The method of claim 1, wherein steps a) through e) are repeated to sequentially form an overlying AlCu via followed by an overlying AlCu interconnect line. 3. The method of claim 1, wherein the AlCu via process is a magnetron sputtering process carried out at a temperature less than about 400° C. 4. The method of claim 3, wherein the AlCu via process is carried out at pressure less than about 5 milliTorr. 5. The method of claim 1, wherein the dielectric insulating layer is selected from the group consisting of carbon doped silicon oxide, organo silicate glass (OSG), and fluorinated silicate glass (FSG). 6. The method of claim 1, wherein the dielectric insulating layer consists essentially of fluorinated silicate glass (FSG). 7. The method of claim 1, wherein the barrier layer is selected from the group consisting of Ti/TiN, TiN, Ta, TaN, and combinations thereof. 8. The method of claim 1, wherein the conductive area comprises silicide electrical contact areas comprising a CMOS transistor portion selected from the group consisting of a gate electrode and source and drain regions. 9. The method of claim 8, wherein the silicide electrical contact areas comprise a metal silicide selected from the group consisting of TiSi2 and CoSi2. 10. The method of claim 8, wherein the CMOS transistor forms a portion of a circuit selected from the group consisting of logic circuitry, memory circuitry, analog circuitry, or combinations thereof. 11. The method of claim 1, wherein steps a) through f) are repeated to form at least 3 metallization layers over a PMD layer. 12. The method of claim 1, wherein steps a) through f) are repeated to form a multi-level semiconductor device consisting essentially of AlCu wiring. 13. A method of forming a multi-level semiconductor device wiring interconnect structure to improve electrical properties including an electro-migration resistance and electrical resistance comprising the steps of: a) forming a dielectric insulating layer over a conductive portion; b) forming a via opening in closed communication with the conductive portion; c) forming a barrier layer to line the via opening; d) forming a layer of AlCu at a temperature less than about 400° C. to fill the via opening to form an AlCu via including a portion overlying the first dielectric insulating layer; e) forming the portion to form an AlCu interconnect line over the AlCu via; and, f) forming a barrier layer over the AlCu interconnect line. 14. The method of claim 13, wherein steps a) through f) are repeated to sequentially form overlying AlCu vias followed by overlying AlCu interconnect lines through at least 3 metallization level. 15. The method of claim 13, wherein the process is a carried out at pressure less than about 5 milliTorr. 16. The method of claim 13, wherein the dielectric insulating layer consists essentially of fluorinated silicate glass (FSG). 17. The method of claim 13, via openings are formed with an aspect ratio greater than 1.5. 18. The method of claim 13, wherein the barrier layers are selected from the group consisting of Ti/TiN, TiN, Ta, TaN, and combinations thereof. 19. The method of claim 13, wherein the conductive area comprises salicide electrical contact comprising a CMOS transistor portion selected from the group consisting of a gate electrode and source and drain regions. 20. The method of claim 19, wherein the salicide electrical contact areas comprise a metal silicide selected from the group consisting of TiSi2 and CoSi2. 21. The method of claim 19, wherein the CMOS transistor forms a portion of a circuit selected from the group consisting of logic circuitry, memory circuitry, analog circuitry, and combinations thereof. 22. The method of claim 13, wherein steps a) through f) are repeated to form at least 3 metallization layers over a PMD layer. 23. The method of claim 13, wherein steps a) through f) are repeated to form a multi-level semiconductor device consisting essentially of AlCu wiring. 24. A multi-level wiring interconnect structure for a semiconductor device comprising: a) a dielectric insulating layer over a conductive portion; b) an AlCu via comprising a first barrier layer formed in the first dielectric insulating layer in closed communication with the conductive portion; and, c) an AlCu interconnect line comprising a second barrier layer disposed on the AlCu via and over the first dielectric insulating layer. 25. The multi-level wiring interconnect structure of claim 24, wherein structure portions a) through c) are stacked sequentially to comprise at least three metallization layers. 26. The multi-level wiring interconnect structure of claim 24, wherein structure portions a) through c) are stacked sequentially to comprise at least three metallization layers. 27. The multi-level wiring interconnect structure of claim 24, wherein structure portions a) through c) are stacked sequentially to form a multi-level semiconductor device consisting essentially of AlCu wiring. 28. The multi-level wiring interconnect structure of claim 24, wherein the dielectric insulating layer is selected from the group consisting of carbon doped silicon oxide, organo silicate glass (OSG), and fluorinated silicate glass (FSG). 29. The multi-level wiring interconnect structure of claim 24, wherein the dielectric insulating layer consists essentially of fluorinated silicate glass (FSG). 30. The multi-level wiring interconnect structure of claim 24, via openings are formed with an aspect ratio greater than 1.5. 31. The multi-level wiring interconnect structure of claim 24, wherein the first and second barrier layers are selected from the group consisting of Ti/TiN, TiN, Ta, TaN, and combinations thereof. 32. The multi-level wiring interconnect structure of claim 24, wherein the conductive portion comprises silicide electrical contact areas comprising a CMOS transistor portion selected from the group consisting of a gate electrode and source and drain regions. 33. The multi-level wiring interconnect structure of claim 31, wherein the silicide electrical contact areas comprise a metal silicide selected from the group consisting of TiSi2 and CoSi2. 34. The multi-level wiring interconnect structure of claim 31, wherein the CMOS transistor forms a portion of a circuit selected from the group consisting of logic circuitry, memory circuitry, analog circuitry, and combinations thereof. 35. A multi-level wiring interconnect structure for a semiconductor device comprising: a) a dielectric insulating layer over a conductive portion; b) an AlCu via comprising a barrier layer formed in the first dielectric insulating layer in closed communication with the conductive portion; wherein structure portions a) through b) are stacked sequentially to comprise at least three metallization layers. 36. The multi-level wiring interconnect structure of claim 35, wherein structure portions a) through c) are stacked sequentially to comprise a PMD layer at least three metallization layers. 37. The multi-level wiring interconnect structure of claim 35, wherein structure portions a) through c) are stacked sequentially to form a multi-level semiconductor device consisting essentially of AlCu wiring. 38. The multi-level wiring interconnect structure of claim 35, wherein the dielectric insulating layer is selected from the group consisting of carbon doped silicon oxide, organo silicate glass (OSG), and fluorinated silicate glass (FSG). 39. The multi-level wiring interconnect structure of claim 35, wherein the dielectric insulating layer consists essentially of fluorinated silicate glass (FSG). 40. The multi-level wiring interconnect structure of claim 35, via openings are formed with an aspect ratio grater than 1.5. 41. The multi-level wiring interconnect structure of claim 35, wherein the barrier layers are selected from the group consisting of Ti/TiN, TiN, Ta, TaN, and combinations thereof. 42. The multi-level wiring interconnect structure of claim 35, wherein the conductive portion comprises silicide electrical contact areas comprising a CMOS transistor portion selected from the group consisting of a gate electrode and source and drain regions. 43. The multi-level wiring interconnect structure of claim 42, wherein the silicide electrical contact areas comprise a metal silicide selected from the group consisting of TiSi2 and CoSi2. 44. The multi-level wiring interconnect structure of claim 42, wherein the CMOS transistor forms a portion of a circuit selected from the group consisting of logic circuitry, memory circuitry, analog circuitry, and combinations thereof. | FIELD OF THE INVENTION This invention generally relates to large scale integrated circuit (LSI) processing methods including formation of metallization interconnects and more particularly to an improved method and structure for wiring a multi-level semiconductor device. BACKGROUND OF THE INVENTION Metallization interconnects are critical to the proper electronic function of semiconductor devices. Several advances in integrated circuit manufacturing processing have been aimed at improving signal transport speed by reducing metal interconnect resistivities and improving resistance to electromigration effects. Copper has increasingly become a metal of choice in, for example, upper levels of metallization in a multi-level semiconductor device due to its low resistivity. Tungsten (W), however, has been used in the lower metallization layers, for example the PMD layer to form plugs or vias to contact underlying conductive areas including CMOS source and drain regions since it provides an effective diffusion barrier to metal diffusion from overlying copper metallization layers. Tungsten further has had acceptable resistance to electromigration in characteristic device dimensions of greater than about 0.25 microns and can effectively fill high aspect ratio vias by chemical vapor deposition (CVD) processes. As device characteristic dimensions shrink, however, the prior art practice of forming tungsten plugs in lower metallization layers creates several problems. For example, the cost and complexity of processing increases, requiring increasing complex processing including tungsten deposition, tungsten dry etchback and/or CMP planarization processes to avoid respectively, for example, voids in tungsten plugs, tungsten particle contamination, and the formation of tungsten metal stringers. In addition, the electrical performance properties of tungsten, including electrical resistance are less than adequate for characteristic device dimensions less than about 0.25 microns. Moreover, the high temperature deposition processes currently required for tungsten as well as overlying conventional copper metallization leads to undesirable defects in previously deposited metallization layers. Therefore, there is a need in the semiconductor processing art to develop an improved integrated circuit wiring structure and method for forming the same to achieve improved electrical performance as well as decreased processing complexity. It is therefore an object of the invention to provide an improved integrated circuit wiring structure and method for forming the same to achieve improved electrical performance as well as decreased processing complexity, while overcoming other shortcomings of the prior art. SUMMARY OF THE INVENTION To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides a multi-level semiconductor device wiring interconnect structure and method of forming the same to improve electrical properties and reliability of wiring interconnects including an electromigration resistance and electrical resistance. In a first embodiment, the method includes forming a dielectric insulating layer over a conductive portion; forming a via opening in closed communication with the conductive portion; forming a first barrier layer to line the via opening; forming a layer of AlCu according to a sputtering process to fill the via opening to form an AlCu via including a portion overlying the first dielectric insulating layer; and, photolithographically patterning and dry etching the portion to form an AlCu interconnect line over the AlCu via. These and other embodiments, aspects and features of the invention will be better understood from a detailed description of the preferred embodiments of the invention which are further described below in conjunction with the accompanying Figures. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1E are cross sectional side view representations of a portion of a multi-level integrated circuit ages in manufacture according to the method of the present invention. FIG. 2 is a cross sectional view of an exemplary multi-level wiring semiconductor device according to an embodiment of invention. FIG. 3 is a process flow diagram including several embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the method of the present invention is explained by reference to an exemplary generic multi-level integrated it including CMOS transistor devices, it will be appreciated that the method of the present invention is particularly applicable to formation of logic circuits, and y circuits, including heterogeneous integrated circuits as mixed signal circuitry including analog conditioning circuitry and combinations of the foregoing, where the advantages of increased electromigration resistance, reduced RC delay time constant, and reduced via contact resistance are particularly advantageous. In addition, although the method of the present invention may be applied to integrated circuits with characteristic dimensions greater than about 0.25 microns, the structure and method of the present invention is particularly advantageous for integrated circuits with characteristic device dimensions less than about 0.25 microns, including 0.18 microns and 0.13 microns. Referring to FIGS. 1A-1E, in an exemplary embodiment of the method of the present invention, cross sectional side view portions of a multi-level integrated circuit is shown at stages in an exemplary manufacturing process. Referring to FIG. 1A, is shown a semiconductor substrate 12, for example, including, but is not limited to, silicon, silicon on insulator (SOI), stacked SOI (SSOI), stacked SiGe on insulator (S—SiGeOI), SiGeOI, and GeOI, and combinations thereof. Still referring to FIG. 1A, formed on the semiconductor substrate 12 is a conventional CMOS device 14, for example including a gate dielectric portion 14A and gate electrode portion 14B. Spacers e.g., 16, are formed adjacent either side of the CMOS device by conventional methods which may include forming composite layers of oxide and nitride. Doped source and drain regions e.g., 18 are formed by conventional methods using the spacers to align the source and drain regions. The CMOS device 14 preferably forms a portion of a logic circuit, a memory circuit, an analog circuit, or a heterogeneous (mixed signal) integrated circuit including combinations of the foregoing. In an important aspect of the invention, self aligned metal silicide (salicide) regions e.g., 20A, 20B, and 20C are formed over source and drain regions e.g., 18 and over the gate electrode portion 14B, by conventional processes including depositing a metal layer over the process surface followed by an annealing process to form a low resistance silicide phase, preferably TiSi2 or CoSi2. The excess metal e.g., Co or Ti is then removed by a wet etching process to leave the salicide regions 20A, 20B, and 20C. Referring to FIG. 1B, a contact etch stop (CES) layer 22 is then formed over the CMOS device 14, preferably formed of silicon nitride and/or silicon oxynitride by a conventional PECVD or LPCVD process. A first dielectric insulating layer 24, also referred to as a pre-metal dielectric (PMD) is then formed over the CES layer 22, followed by a planarization step, for example CMP. One or more via openings e.g., 26A and 26B are then etched through the dielectric insulating layer and through the CES layer 22 to contact salicide regions e.g., 20A, 20B and optionally 20C (not shown). In an important aspect of the invention, the via openings e.g., 26A and 26B are formed with an aspect ration greater than about 1.5, more preferably greater than about 2.8, preferably having substantially vertical sidewalls, for example having a sidewall angle with respect to horizontal of greater than about 85 degrees. The dielectric insulating layer 24 is preferably formed of a low-K dielectric having a dielectric constant less than about 3.5, most preferably fluorinated silicate glass (FSG) formed by a conventional HDP-CVD or PECVD process, but which may also be formed of another silicon oxide based material such as BPSG or BPTEOS. Referring to FIG. 1C, a barrier layer e.g., 28 of Ti/TiN, TiN, Ta, TaN, or combinations thereof, is first formed to line the via openings. Preferably the barrier layer is deposited with a thickness less than about 400 Angstroms to decreases a contact electrical resistance of the vias. The barrier layer 28 may be deposited by a conventional PVD process with a collimator but is more preferably deposited according to a low temperature and low pressure magnetron sputtering process, for example at a temperature less than about 400° C., including at about room temperature for example, less than about 30° C., and at a pressure of less than about 5 milliTorr. In another aspect of the invention, following formation of the barrier layer 28, preferably according to a magnetron sputtering process the remaining portion of the via openings are filled with an AlCu alloy filling 30, according to a low pressure magnetron sputtering process, preferably at pressures less than about 5 milliTorr, and at temperatures less than about 400° C., including at about room temperature for example, less than about 30° C. The AlCu preferably has a copper content of about 2 to about 10 atomic weight percent with respect to aluminum. In the case magnetron sputtering is used to form the barrier layer, the AlCu deposition may be performed in-situ improving metal adhesion to the barrier layer. Alternatively, the barrier layer 28 may be formed by a convention PVD process prior to depositing the AlCu by the low temperature/low pressure magnetron sputtering process. Referring to FIG. 1D, following formation of the AlCu layer 30, a conventional photolithographic patterning process is carried out to pattern metal lines over the vias followed by a metal etching process to form AlCu interconnect lines e.g., 32A and 32B contiguous with underlying via portions. Optionally, a second barrier layer 33A, the same or different material as the first barrier layer 28 may be blanket deposited over the AlCu interconnect lines e.g., 32A, and 32B by a conventional PVD process or the low pressure magnetron processes previously outlined, prior to forming an overlying IMD layer explained below. Advantageously, a CMP process and formation of a capping layer required in prior art damascene processes prior to forming the interconnect lines e.g., 32A and 32B is unnecessary according to the present invention. Still referring to FIG. 1D, a second dielectric insulating layer, also referred to as an inter-metal dielectric (IMD) layer 34, also referred to as metallization layer e.g., M2 following formation of metal interconnects, is formed over the AlCu interconnect lines e.g., 32A and 32B. The IMD layer 34 is preferably formed of FSG. An ARC layer (not shown) is preferably formed over the IMD layer 34 followed by a conventional photolithographic patterning process to pattern second via openings overlying the AlCu interconnect lines 32A and 32B respectively, followed by a conventional dry etching process to form second via openings 36A and 36B exposing the underlying interconnect lines e.g., 32A and 32B. Referring to FIG. 1E, a third barrier layer e.g., 33B the same or different material as the first and second barrier layers is then first formed to line the via openings followed by the low pressure/low temperature magnetron sputtering process carried out in the same manner as previously outlined to deposit AlCu layer 38 to fill the via openings 36A and 36B including a portion overlying the IMD layer 34 surface. A second photolithographic patterning and dry metal etching process is then carried out as previously outlined to form AlCu interconnect lines 40A and 40B contiguous with via portions. The previously outlined processes may then be sequentially repeated to form overlying metallization portions making up overlying metallization layers in a similar manner. Referring to FIG. 2, is shown a portion of an exemplary multi-level integrated circuit wiring structure according to an embodiment of the invention. For example, shown is PMD layer and metallization layers e.g., M1, M2, a portion of M3 and an uppermost metallization layer e.g., M7. In one embodiment, all or a portion of the metallization layers e.g., M1 through M7 as well as the PMD layer including contact via portion of the PMD metallization e.g., 44A are formed by carrying out the processes previously outlined in FIGS. 1A-1E for each of the metallization layers e.g., M1 through M7. It will be appreciated that the number of metallization layers may be more or less than 7. In another embodiment, at least the first two metallization layers e.g., M1 and M2, more preferably at least the first 3 metallization layers, e.g., M1 through M3 include metal interconnect lines e.g., 46A, 46B, and 46C overlying and contiguous with via portions e.g., 44A, 44B, and 44C, formed of AlCu according to preferred embodiments outlined in FIGS. 1A through 1E. The dielectric insulating layers (IMD layers) corresponding to the metallization layers e.g., M1 through M7 are preferably formed of FSG to add increased metal diffusion resistance and barrier layer adhesion. In another embodiment, the contact via portion e.g., 44A formed in the PMD layer to contact silicide portion 42A (e.g., S/D region- CMOS device not shown) formed on semiconductor substrate 42, is formed of tungsten by a conventional tungsten plug formation process followed by forming the overlying metallization portions at least through M3, of AlCu according to preferred embodiments. More preferably, however, the contact via e.g., 44A is formed of AlCu and is contiguous with interconnect line portion 46A as previously outlined. It will also be appreciated that metallization portions in M3 or above overlying an AlCu metallization portion e.g., interconnect line portion 46C may be formed by conventional copper damascene processes where the dielectric insulating layer may be formed of either FSG or a porous silicon oxide low-K material such as carbon doped oxide or OSG. In addition, the uppermost metallization later e.g., M7 is preferably formed of AlCu including contiguous metallization portion e.g., 48B overlying conductive line 48A e.g., AlCu formed according to preferred processes. It will be appreciated that all of the metallization layers including the PMD layer may be formed of AlCu according to preferred embodiments. Thus an improved method for forming wiring in large scale integrated circuitry has been presented whereby interconnect lines are formed with improved reliability and void free at low temperatures thereby reducing defects induced by higher temperature processes. In addition, the AlCu wiring has improved electromigration resistance compared to copper and/or tungsten and has no via/interconnect line interface electrical resistance within a metallization layer. Advantageously, the process according to the present invention avoids costly CMP processes to planarize a metallization layer e.g., in a damascene or dual damascene process prior to forming an overlying metallization layer and eliminates the need for capacitance contributing etch stop and capping layers between metallization layers. For example, it has been found that by using a low-temperature and low pressure magnetron sputtering process according to the present invention, high aspect ratio openings, for example greater than about 2.8 may be filled with the preferred AlCu alloys void free, with improved adhesion and lower electro-migration resistance and a lower via/interconnect line electrical resistance. This is especially advantageous in back-end-of-line wiring processes, since prior art processes carried out at higher temperatures e.g., greater than about 400° C. can lead to void formation and thermally induced defects in underlying metallization layers as well as undesired dopant diffusion in doped CMOS regions. Thus, the method and multi-level wiring structure of the present invention is especially advantageous for multi-level semiconductor devices having characteristic dimensions less than about 0.25 microns including logic circuits, memory circuits, analog circuits, as well as heterogeneous integrated circuits including embedded combinations of the foregoing. Referring to FIG. 3 is a process flow diagram including several embodiments of the present invention. In a first process 301, a semiconductor substrate including CMOS transistors with salicides contact areas is provided. In process 303, a PMD dielectric insulating layer is formed over the CMOS transistors. In process 305, first vias are formed in closed communication with salicide areas. In process 307, a first barrier layer is formed to line the first vias. In process 309, an AlCu layer is deposited by low temp process to backfill the vias according to preferred embodiments including a portion overlying the PMD layer. In process 311, AlCu interconnect lines are patterned and etched in the overlying AlCu portion. In process 313, a second barrier layer is formed over the AlCu interconnect lines. In process 315, an IMD dielectric insulating layer is formed over the interconnect lines. As indicated by process arrow 317, processes 307 through 315 are sequentially repeated to form AlCu vias and interconnect lines in overlying levels through at least the third metallization level (M3). The preferred embodiments, aspects, and features of the invention having been described, it will be apparent to those skilled in the art that numerous variations, modifications, and substitutions may be made without departing from the spirit of the invention as disclosed and further claimed below. | <SOH> BACKGROUND OF THE INVENTION <EOH>Metallization interconnects are critical to the proper electronic function of semiconductor devices. Several advances in integrated circuit manufacturing processing have been aimed at improving signal transport speed by reducing metal interconnect resistivities and improving resistance to electromigration effects. Copper has increasingly become a metal of choice in, for example, upper levels of metallization in a multi-level semiconductor device due to its low resistivity. Tungsten (W), however, has been used in the lower metallization layers, for example the PMD layer to form plugs or vias to contact underlying conductive areas including CMOS source and drain regions since it provides an effective diffusion barrier to metal diffusion from overlying copper metallization layers. Tungsten further has had acceptable resistance to electromigration in characteristic device dimensions of greater than about 0.25 microns and can effectively fill high aspect ratio vias by chemical vapor deposition (CVD) processes. As device characteristic dimensions shrink, however, the prior art practice of forming tungsten plugs in lower metallization layers creates several problems. For example, the cost and complexity of processing increases, requiring increasing complex processing including tungsten deposition, tungsten dry etchback and/or CMP planarization processes to avoid respectively, for example, voids in tungsten plugs, tungsten particle contamination, and the formation of tungsten metal stringers. In addition, the electrical performance properties of tungsten, including electrical resistance are less than adequate for characteristic device dimensions less than about 0.25 microns. Moreover, the high temperature deposition processes currently required for tungsten as well as overlying conventional copper metallization leads to undesirable defects in previously deposited metallization layers. Therefore, there is a need in the semiconductor processing art to develop an improved integrated circuit wiring structure and method for forming the same to achieve improved electrical performance as well as decreased processing complexity. It is therefore an object of the invention to provide an improved integrated circuit wiring structure and method for forming the same to achieve improved electrical performance as well as decreased processing complexity, while overcoming other shortcomings of the prior art. | <SOH> SUMMARY OF THE INVENTION <EOH>To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides a multi-level semiconductor device wiring interconnect structure and method of forming the same to improve electrical properties and reliability of wiring interconnects including an electromigration resistance and electrical resistance. In a first embodiment, the method includes forming a dielectric insulating layer over a conductive portion; forming a via opening in closed communication with the conductive portion; forming a first barrier layer to line the via opening; forming a layer of AlCu according to a sputtering process to fill the via opening to form an AlCu via including a portion overlying the first dielectric insulating layer; and, photolithographically patterning and dry etching the portion to form an AlCu interconnect line over the AlCu via. These and other embodiments, aspects and features of the invention will be better understood from a detailed description of the preferred embodiments of the invention which are further described below in conjunction with the accompanying Figures. | 20040330 | 20061010 | 20051006 | 77782.0 | 0 | LEE, HSIEN MING | BACK END IC WIRING WITH IMPROVED ELECTRO-MIGRATION RESISTANCE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,813,963 | ACCEPTED | Query progress estimation | A query progress indicator that provides an indication to a user of the progress of a query being executed on a database. The indication of the progress of the query allows the user to decide whether the query should be allowed to complete or should be aborted. One method that may be used to estimate the progress of a query that is being executed on a database defines a model of work performed during execution of a query. The total amount of work that will be performed during execution of the query is estimated according to the model. The amount of work performed at a given point during execution of the query is estimated according to the model. The progress of the query is estimated using the estimated amount of work at the given point in time and the estimated total amount of work. This estimated progress of query execution may be provided to the user. | 1. A method of estimating query progress, comprising: a) defining a model of work performed during execution of a query; b) estimating a total amount of work that will be performed according to the model during execution of the query; c) estimating an amount of work performed according to the model at a given point during the execution of the query; and d) estimating the progress of the query using the amount of work performed and the total amount of work. 2. The method of claim 1 further comprising displaying estimated progress of the query to a user. 3. The method of claim 1 wherein work performed during execution of a query is modeled as a number items returned by a query operator. 4. The method of claim 1 wherein work performed during execution of a query is modeled as a number of GetNext( ) calls by a query operator. 5. The method of claim 1 wherein the work performed during execution of the query is modeled as work performed by a driver node operator during execution of the query. 6. The method of claim 1 wherein work performed by a driver node operator is modeled as a number of items returned by the driver node operator. 7. The method of claim 1 wherein work performed by a driver node operator is modeled as a number of GetNext( ) calls by a driver node operator. 8. The method of claim 1 further comprising dividing a query execution plan into a set of pipelines and estimating the progress of each pipeline. 9. The method of claim 8 wherein the pipelines comprise sequences of non-blocking operators. 10. The method of claim 8 further comprising combining progress estimates for the pipelines to estimate the progress of the query. 11. The method of claim 8 further comprising initializing an estimate of the total amount of work that will be performed by a pipeline with an estimate from a query optimizer. 12. The method of claim 1 further comprising refining the initial estimate of the total work using feedback obtained during query execution. 13. The method of claim 8 further comprising identifying driver node operators of the pipeline and modeling the work performed during execution of the pipelines as work performed by the driver node operators. 14. The method of claim 8 further comprising modeling the work performed during execution of the pipelines as work performed by all operators in the pipeline. 15. The method of claim 8 further comprising identifying driver node operators of the pipeline and using information about the driver node operators obtained during execution to estimate a total amount of work that will be performed by all operators in the pipeline. 16. The method of claim 2 further comprising preventing decreasing progress estimations from being displayed to the user. 17. The method of claim 16 wherein decreasing progress estimations are prevented by using an upper bound on the total work that will be performed as an estimate of the total work that will be performed. 18. The method of claim 1 further comprising identifying a spill of tuples during query execution and adjusting the model of work to account for additional work that results from the spill of tuples. 19. The method of claim 10 further comprising assigning weights to the pipelines. 20. The method of claim 19 wherein the weights are based on relative execution rates of the pipelines. 21. The method of claim 1 further comprising updating an estimated total amount of work that will be performed during query execution. 22. The method of claim 1 wherein an estimated amount of work performed according to the model is updated at a plurality of points during query execution. 23. The method of claim 1 further comprising maintaining an upper bound and a lower bound on the on the total amount of work that will be performed and modifying an estimated total amount of work that will be performed when the estimated total amount of work that will be performed is outside a range defined by the upper bound and the lower bound. 24. The method of claim 3 further comprising maintaining an upper bound and a lower bound on the on a total number of items that will be returned by the query operator and modifying an estimated total number of items that will be returned by the query operator when the estimated total number of items that will be returned by the query operator is outside a range defined by the upper bound and the lower bound. 25. The method of claim 24 wherein a rule used for maintaining a bound on the total number of items that will be returned by the query operator is specific to the query operator. 26. The method of claim 25 wherein the query operator is a Group By operator and the rule used for maintaining an upper bound on a number of groups that will be returned by the Group By operator comprises subtracting a number of items returned by an immediately preceding operator in a query execution plan from an upper bound of the immediately preceding operator and adding a number of distinct values observed by the Group By operator. 27. The method of claim 25 wherein the query operator is a Hash Join operator and the rule used for maintaining an upper bound on the number of rows that will be returned by the Hash Join operator comprises subtracting a number of items returned by an immediately preceding operator in a query execution plan from an upper bound of the immediately preceding operator and multiplying a number of rows of a largest build partition. 28. The method of claim 24 further comprising setting the lower bound to a number of items returned by the query operator at a given point during query execution. 29. The method of claim 24 wherein the upper bound of the query operator is maintained using an upper bound of one or more preceding query operators in a query execution plan. 30. The method of claim 29 wherein the upper bound of the query operator is maintained using an upper bound of an immediately preceding query operator in the query execution plan. 31. The method of claim 24 wherein the upper bound of the query operator is maintained using a number of items returned by one or more preceding operators in a query execution plan at a given point during query execution. 32. The method of claim 31 wherein the upper bound of the query operator is maintained using a number of items returned by an immediately preceding query operator in the query execution plan. 33. The method of claim 24 wherein the upper bound of the query operator is maintained using a number of items returned by the query operator at a given point during query execution. 34. The method of claim 24 wherein upper and lower bounds are maintained for a plurality of query operators in a query execution plan and wherein a changes in bounds of query operators are periodically propagated to other query operators in the query execution plan. 35. Computer readable media comprising computer-executable instructions for performing the method of claim 1 36. In a computer system including a display, a user input facility, and an application for presenting a user interface on the display, a user interface comprising: a) a query progress indicator that provides an indication to a user of an execution state of a query; and b) a query end selector that allows the user to abort execution of the query. 37. The user interface of claim 36 wherein the query progress indicator provides a visual indication of a percentage of query execution that has been completed. 38. The user interface of claim 37 wherein the percentage of query execution that has been completed is estimated by dividing a number of tuples returned by the query by an estimated total number of tuples to be returned by the query. 39. The user interface of claim 37 wherein the percentage of query execution that has been completed is estimated by dividing a number of tuples returned by an operator by an estimated total number of tuples to be returned by the operator. 40. The user interface of claim 37 wherein the percentage of query execution that has been completed is estimated by dividing a GetNext( ) calls by a query operator by an estimated total number of GetNext( ) calls by the operator. 41. The user interface of claim 37 further comprising initializing the estimated total number of GetNext( ) calls with an estimate from a query optimizer. 42. The user interface of claim 41 wherein initial estimate of the total number of GetNext( ) calls is updated using feedback obtained during query execution. 43. The user interface of claim 36 the query progress indicator is prevented from providing an indication of decreasing query progress. 44. The user interface of claim 36 further comprising a tuple spill indicator that alerts a user when tuples spill to disk during query execution. 45. A system for providing an indication of query progress, comprising: a) a user input device enabling a user to begin execution of a query and abort execution of a query; b) a display; c) a data content that queries can be executed upon; d) a memory in which machine instructions are stored; e) a processor that is coupled to the user input device, to the display, to the data content, and to the memory, the processor executing the machine instructions to carry out a plurality of functions, including: i) executing a query upon the data content; ii) monitoring progress of the query; and iii) providing an indicator of query progress on the display. 46. The system of claim 45 wherein query progress is estimated as an amount of work performed at a current point of query execution divided by an estimated total amount of work. 47. The system of claim 45 wherein the processor identifies a spill of tuples during query execution and provides an indication of the spill on the display. 48. The system of claim 45 the indicator of query progress provides a visual indication of a percentage of query execution that has been completed. | FIELD OF THE INVENTION The present invention concerns a method of estimating the progress of queries executed on a database. BACKGORUND ART Decision support queries can be expensive and long-running. Today's database systems do not provide feedback to a user, such as a database administrator (DBA), on how much of a query's execution has been completed. That is, today's database systems are not able to provide a “progress bar” that indicates how much of a query has executed and how much of a query remains to be executed. While today's database management systems can provide much information about query execution at the end of the execution, typically the only information available during query execution is the number of output tuples generated thus far by the query, the execution plan for the query chosen by the optimizer at compile time, and the estimated cost and estimated cardinality of the query. However, this information is insufficient for reporting progress of query execution for the following reasons. The number of tuples output by a query at a given point during query execution does not provide an indication of what the total number of tuples output by the query will be. Moreover, for some queries, no tuple may be output until quite late in the query execution. Existing database systems include optimizers that use a cost model to compare different query evaluation plans. This cost model is not intended to be an accurate model of execution time. Optimizer estimates of cardinality are known to be susceptible to errors. There is a need for a method of estimating query progress. For long running queries, running estimations of query progress would be very useful. For example, an indication of query progress would help the DBA decide whether the query should be terminated or allowed to run to completion. SUMMARY The present disclosure concerns a query progress indicator that provides an indication to a user of the progress of a query being executed on a database. The indication of the progress of the query allows the user to decide whether the query should be allowed to complete or should be aborted. One method that may be used to estimate the progress of a query that is being executed on a database defines a model of work performed during execution of a query. The total amount of work that will be performed during execution of the query is estimated according to the model. The amount of work performed at a given point during execution of the query is estimated according to the model. The progress of the query is estimated using the estimated amount of work performed up to the given point and the estimated total amount of work. This estimated progress of query execution can be provided to the user. The work performed during execution of the query may be modeled in a variety of ways. For example, work performed during execution of a query could be modeled as a number items returned, such as tuples or groups returned, or a number of GetNext( ) calls. In one embodiment, the work performed during execution of the query is approximated as the work performed by a subset of operators of the query. For example, the work performed during execution of the query could be modeled as work performed by one or more driver node operators during execution of the query. In one embodiment, a query execution plan is divided into a set of pipelines, the progress of each pipeline is estimated, and the estimates from the pipelines are combined and returned as the progress of the query. The pipelines comprise sequences of non-blocking operators. In one embodiment, the total amount of work that will be performed by a pipeline is initialized with an estimate from a query optimizer or another source. In one embodiment, the initial estimate of total work is be refined using feedback obtained during query execution. For example, the total work can be refined by maintaining upper and lower bounds on the total work that will be performed. The initial estimate is then refined when it violates the upper or lower bound. Upper and lower bounds may be maintained for each of the operators in each pipeline with bound defining rules for each different type of operator. In one embodiment, the upper and lower bounds are defined in terms of a number of items returned so far by the query operator, the number of items returned so far by one or more preceding query operators, and/or the upper and/or lower bounds of one or more preceding operators. In one embodiment, changes in bounds of query operators are periodically propagated up the query execution plan to allow the bounds of following query operators in the execution plan to be updated. In one embodiment, driver node operators are identified for each pipeline. In this embodiment, the work performed during execution of the pipelines is modeled as work performed by the driver node operators. In one embodiment, weights are assigned to the pipelines that make up the query. These weights may be based on relative execution rates of the pipelines. In one embodiment, the method identifies a spill of tuples to disk during query execution. The model of work may be adjusted to account for additional work that results from the spill of tuples and/or an indicator may be provided that alerts the user that the spill has occurred. In one embodiment, computer readable instructions for performing a method for estimating query progress are stored on computer readable media. The computer readable instructions can be stored in a memory of a system for providing an indication of query progress. Such a system includes a user input device, a display, a data content, and a processor. The user input device enables a user to begin execution of a query and abort execution of a query. The processor is coupled to the user input device, to the display, to the data content, and to the memory. The processor executes the machine instructions to execute a query upon the data content, monitor progress of the query, and provide an indicator of query progress on the display. In one embodiment, the query progress indicator provides a visual indication of a percentage of query execution that has been completed. In one embodiment, decreasing progress estimations are prevented from being displayed. These and other objects, advantages, and features of an exemplary embodiment are described in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a database query progress indicator; FIG. 2 is a flow chart that illustrates a method of estimating query progress; FIG. 3 is a flow chart that illustrates a method of estimating query progress; FIG. 4 is an illustration of a query execution plan; FIG. 5 is an illustration of a query execution plan; FIG. 6 is a flow chart that illustrates a method of estimating query progress; FIG. 7 is an illustration of a query execution plan; FIG. 8 is an illustration of a query execution plan; FIG. 9 is an illustration of a query execution plan; FIG. 10 is a flow chart that illustrates a method of adjusting an optimizer estimate; FIG. 11 is an illustration of a query execution plan divided into pipelines; FIG. 12 is a flow chart that illustrates a method of adjusting an optimizer estimate; and FIG. 13 is a schematic depiction of a computer system used in practicing an exemplary embodiment of the disclosed method. DETAILED DESCRIPTION Query Progress Indicator FIG. 1 illustrates an example of a progress indicator 100 that provides an indication to a user of the progress of a query being executed on a database 102. The illustrated progress indicator 100 forms part of a user interface 104 of a database system 106. The illustrated progress indicator 100 includes a progress bar 108 and a numeric representation 110 of query progress. The illustrated user interface 104 includes a user input button 112 that facilitates aborting of the query. FIG. 2 is a flow chart that illustrates one method that can be used to estimate query. In this method, a model of work performed during query execution is defined 114. The total amount of work that will be performed during execution of the query is estimated 116 according to the model. The amount of work performed at a given or current point during execution of the query is estimated 118. The progress of the query is estimated 120 using the estimated amount performed at the given point and the estimated total amount of work. For example, the query progress is expressed as the estimated work performed up to the current point of execution divided by the estimated total work that will be performed during query execution. In the method illustrated by FIG. 2, query progress is reported in terms of work done in executing a query, rather than an amount of time left for the query to complete execution. Reporting the amount of time left for a query to complete execution requires modeling of runtime issues, such as time variations due to executing concurrent queries, caching, disk rates etc. These runtime issues make estimating the amount of time for a query to complete execution difficult. In the embodiment illustrated by FIG. 2, the direct influence of runtime issues is isolated by estimating what percentage of the total work of the query is completed at any instant, rather than estimating the amount of time that is required for the query to complete execution. In the embodiment illustrated by FIG. 1, query progress is presented as a single number or progress bar. Using a single number or progress bar to report the progress estimation is a paradigm that users are already familiar that is easy to understand/interpret. In another embodiment multiple progress estimation numbers or bars are presented for a query. For example, the progress of each node of a query execution plan can be presented. Model of Work Query progress estimation is difficult in its most general setting. Database systems can have widely fluctuating runtime conditions. This makes it difficult to develop a model of work that can be used to accurately model query execution time. In an exemplary embodiment, work W is modeled as a number of items, such as tuples or groups, returned by one or more query operators. In this application, query operators refers to physical operators in a query execution plan. This measure of work is independent of time and is invariant across query runs. In one embodiment, the model of work is based on the observation that in most existing database systems, query operators are usually implemented using an iterator model. In the iterator model, each physical query operator in the query execution plan exports a standard interface for query processing. The operators in this interface include Open( ), Close( ) and GetNext( ) calls. Each time a GetNext( ) operator is issued an item, such as a tuple or group is returned. Referring to FIG. 4, the work W is modeled 122 as the total number of GetNext( ) calls issued throughout the query pipeline including the root in one embodiment. The method counts 124 each GetNext( ) call K as a primitive operation of query processing and models 126 the total work done by the query as the total number N of GetNext( ) calls. Query progress is then estimated 128 by dividing the GetNext( ) count by the estimated total number of GetNext( ) operators. This model though simple has a number of advantages. This model can be applied to any SQL query as most modern database system do employ a demand driven model for query evaluation. This measure of work is invariant across multiple query runs. It is simple and hence can easily be analyzed. Difficulties Associated with Estimating Total Number of GetNext Calls The total number N of GetNext( ) calls that will be issued during query execution is not known until execution is complete. In an exemplary embodiment, the model of work W based on GetNext( ) calls is refined to ensure that an estimator E is within a constant factor of an ideal estimator I. At any point during execution, if the current number of GetNext( ) calls issued anywhere in the pipeline is a number k and the total number of GetNext( ) calls is a number N, the progress can be reported as a fraction (k/N). An ideal estimator I is one which has complete knowledge of the results of the query. Such an estimator would know the exact total number of GetNext( ) calls N and hence would predict progress accurately. At any given point in time, estimator E would have observed the execution until this given point and hence can compute the exact number k of GetNext( ) calls executed so far. The estimator E functions in an ‘online’ fashion in that it predicts a value for the total number of GetNext( ) calls N at every instant. To limit overhead, available to help the estimator E predict the total number of GetNext( ) calls N are limited in the exemplary embodiment. For instance, estimator E could obtain the exact value of the number of GetNext( ) calls N by executing the query, but the cost is prohibitive. As such, in an exemplary embodiment, estimator E method is limited to the class of estimators that obey the following restrictions. 1) The estimator E can access any information it has observed so far in the query evaluation. For example, the output of any operators in the execution tree. 2) The estimator E can use any available statistics that have been pre-computed by the database system. Given this class of estimators E, it is difficult to construct an estimator E such that the estimator E is guaranteed to always to estimate progress within a constant factor of the ideal estimator I. As an example, consider a database containing the following relations. 1. Relation A having a column v which has M elements chosen from the set {1, 2 . . . n} with each element occurring at-most once (M<=n). 2. Relation B having column v. where B=∪Bi (i=1 . . . n) where each Bi={i, i, . . . i} having N elements (column v all with the value i) where N≧c2*M (c is a constant). Thus the size of the database in this example is no more than n2, denoted O(n2). FIG. 4 illustrates an example of an execution plan for a query that joins 142 relation A with relation B on column v, and imposes 144a filter on A (A.v=i). An example of an execution plan 140 for this query is shown in FIG. 4. Assume an adversary exists that is free to re-order the tuples of table A during query execution, and consider a point in time during query execution when k tuples from A have been scanned. Assume an estimator E exists is guaranteed to always be within a constant factor c of the ideal estimator I. Let the exact total number of GetNext( ) calls that will be made for this query be D (thus I=k/D). Then: 1 c · k D ≤ E ≤ c · k D , or equivalently 1 c · k E ≤ D ≤ c · k E There are two possible values for D based on whether or not the value i is actually present in column A.v. Case 1: If the value i is present in A.v, then D=M+N+1 since the total number of GetNext( ) calls would include M for Table Scan of A, exactly one from the Filter node and N from the Join node). Since N≧c2.M, it follows that D>c2.M. Since k/E≧D/c, k/E>c*M Case 2: If the value i is not present in A.v then D=M (no tuple would flow out of the filter and join nodes). In this case, since D=M, and it follows that k/E≦c*M. Thus, the estimator E (after seeing k tuples of table A) by comparing the value of k/E to c*M can say with absolute certainty whether or not the tuple i is present in relation A. Since the adversary is free to reorder the tuples, it can be assumed with generality that tuple i is not among the k tuples scanned so far. So the only way estimator E can conclude that tuple i belongs to relation A is by obtaining this information from the statistics pre-computed by the database system. It is possible that the database may have pre-computed accurate statistics for certain queries (some tuple i values in the example). However, unless the database has pre-computed at least n bits, denoted Ω(n) bits, there would always exist some tuples i for which the estimator E is not within a constant factor of I. Thus, it is difficult to approximate the total number of GetNext( ) calls. Progress Estimation of Single Execution Pipelines In one embodiment, an estimator PROG estimates the progress of a query whose execution plan is a single pipeline by dividing the number ki GetNext( ) calls by a first operator OPi are a given point in time by an estimated total number Ni GetNext( ) calls by operator OPi. A pipeline is a sequence of non-blocking operators. For example, the query execution plan 140 illustrated by FIG. 4 is a single pipeline, because the Index Nested Loops Join 142, the Filter 144, the Index seek 146, and the Table Scan 148 are all non-blocking operators. For the sub-class of queries whose execution plan is a single pipeline, estimator PROG is within a constant factor of the ideal estimate I. Consider the class of queries whose execution plan is a single pipeline consisting of m operators: Op1→Op2 . . . →Opm. Typically, such a pipeline consists of unary physical operators. The only join operator that can execute within a single pipeline is the Index Nested Loops (INL) join since both the Hash Join and Sort-Merge Join are blocking. Let the total number of tuples that flow out of operator Opi at the end of query execution be Ni (i=1 . . . m). At any point during query execution, let the number of tuples that have flowed out of every operator (i.e. number of GetNext( ) calls invoked at that operator) be Ki (i=1 . . . m). Now, consider pipelines in which at any point of time Ki≧Ki+1. In other words, no operator in the pipeline can increase its incoming cardinality. Such a pipeline is referred to as a monotonically decreasing pipeline. Note that this also implies that Ni≧Ni+1. Examples of physical operators that could be part of a monotonically decreasing pipeline are table scans, filter operators and streaming aggregates. The Index Nested Loops Join would also satisfy the above property when the join looks up a key value (i.e. foreign key—key join). For the class of monotonically decreasing pipelines, the disclosed method utilizes an estimator PROG that is within a factor m of the ideal estimator I. If operator Op1 is either a table scan operator or an index scan operator, then the ideal estimator I would predict the progress as: I = ∑ i K i ∑ i N i The estimator has exact information on the numbers of tuples Ki's that have flowed out of every operator so far (which can be observed from query execution) and also information on the total number of tuples N1 to be returned by the operator Op1. The total number of tuples Ni returned by operator Op1 is known since cardinality estimates for a table scan or an index scan are typically accurate. The only other operator that could be operator Op1 for a query whose execution pipeline is a single pipeline is the Index Seek operator. Estimating the total number of tuples N1 for an Index Seek operator Op1 is discussed below. Accurately estimating the rest of the numbers Ni's of tuples returned by other types of operators is challenging. Consider two estimators E1, E2, each of which uses information that is known to be accurate and provides estimates that are within a constant factor of the ideal estimator I for the class of monotonically decreasing single pipeline queries. Estimator E1 is a pessimistic estimator which would always under-predict the progress. Estimator E2 is an optimistic estimator that always over-predicts the progress. Estimators E1 and E2 are defined as follows: Estimator E 1 : E 1 = ∑ i Ki N 1 · m Where N1 is the number of tuples that flow out of operator Op1 (the first operator in the pipeline), and m is the number of operators in the pipeline. Claim: For monotonically decreasing pipelines E1 is a lower bound on I within a factor m. Proof: E1/I=ΣiNi/(N1*m). Since, the pipeline is guaranteed to be monotonically decreasing we know that N1≦ΣiNi≦m. N1. In other words: 1/m≦E1/I≦1 or equivalently: I · 1 m ≤ E 1 ≤ I ( 1 ) Hence estimator E1 is always a lower bound of I within a factor m of the number of operators m in the pipeline. Estimator E 2 : E 2 = ∑ i = 1 m Ki N 1 + ∑ i = 2 m Ki Claim: For monotonically decreasing pipelines E2 is an upper bound on I within a factor m. Proof : E 2 I = ∑ i N i ∑ i N i + ∑ i = 2 k K i We know that: ( N 1 + ∑ i = 2 m Ki ) ≤ ∑ i Ni ≤ m · ( N 1 + ∑ i = 2 m Ki ) in other words we have 1≦E2/I≦m, or equivalently, I≦E2≦m·I (2) Hence estimator E2 is always an upper bound of I within a factor m. m is the number of operators m in the pipeline. In an exemplary embodiment, a progress estimator PROG estimates progress of the entire pipeline by just observing the progress of the first operator Op1. The progress estimator PROG estimates always lie between the estimates of E1 and E2 for the case of monotonically decreasing pipelines. As a result, estimator PROG approximates the ideal estimator I within a factor m (m is the number of operators in the pipeline). Even for the general class of all queries that execute in a single pipeline, the progress estimator PROG performs well in many conditions. Referring to FIG. 5, the estimator PROG is based on the assumption that a pipeline 150 is “driven” by the first operator 152 (i.e., the leaf node of the pipeline), which is referred to herein as a driver node in the pipeline. In other words, the estimator PROG approximates the progress of the overall pipeline as equivalent to the progress of the scan of the corresponding driver node of the pipeline. Thus: PROG = K 1 N 1 Claim: For monotonically decreasing pipelines, PROG always lies between estimators E1 and E2. Proof: Compare PROG to the estimators E1 and E2 defined above. ( PROG - E 1 ) = K 1 N 1 - ∑ i Ki m · N 1 . Cross multiplying, ( PROG - E 1 ) = N 1 · m · K 1 - N 1 · ( K 1 + K 2 + … K m ) N 1 · m · N 1 Since the pipeline is monotonically decreasing, m.K1≧(K1+K2+ . . . Km). Therefore, (PROG−E1)≧0 or PROG≧E1. From the definition of E2: E 2 = K 1 + ∑ i = 2 m Ki N 1 + ∑ i = 2 m Ki and since ∑ i = 2 m K i ≥ 0 , E 2 ≥ PROG . Thus, E1≦PROG≦E2. Using Equations (1) and (2) above: I m ≤ E 1 ≤ PROG ≤ E 2 ≤ m . I Thus for a pipeline that is monotonically decreasing, estimator PROG is always within a constant factor m of the ideal estimator I. The constant m is related to the number of operators in the pipeline. If a node other than the ‘driver’ node is used to monitor progress (some other operator Opi), then the corresponding total value Ni needs to be predicted at every instant. One advantage of using estimator PROG is the fact that both K1 and N1 are exact values when operator Opi is a table scan or an index scan. This reduces uncertainty and is likely to make the estimator more robust. Extending Estimator PROG In one embodiment, the PROG estimator is used for the case of single pipelines that are not necessarily limited to monotonically decreasing pipelines. In one embodiment, the PROG estimator is used for the case where the leaf node is not limited to a table scan or an index scan. Situations under which the estimator PROG is an accurate estimator are characterized below. In one embodiment, the PROG estimator is used to estimate the progress of general queries with execution plans that are a single pipeline. Estimator PROG is accurate for the general case of single pipelines. Consider the entire pipeline as a black box. Assume that the input to the pipeline consists of n tuples. Let Cj denote the total work done by the pipeline on tuple j. Then an accurate definition of the progress at any point after k tuples have been processed by the pipeline is: E = ∑ j = 1 k Cj ∑ j = 1 n Cj Let C′ denote the average work per tuple for the k tuples processed so far, and let C″ denote the average work per tuple for the remaining (n-k) tuples that have not yet been processed by the pipeline. The estimator PROG would predict the progress at any instant as k/n. Note that: E = k · C ′ k · C + ( n - k ) · C ′′ which is identical to PROG if C′═C”. In other words, if the average work per tuple processed so far is approximately equal to the average cost per tuple of the remaining tuples, the heuristic estimator PROG is accurate even for execution pipelines that are not monotonically decreasing. To this point in the disclosure, it has been assumed that the driver operator Op1 is a Table scan or an Index scan. When the query executes, the only other possibility is that the leaf node is an Index Seek. In this case the value N1 used for the driver node is no longer guaranteed to be an exact value. There could certainly be cases in which the optimizer estimate for N1 is very accurate. For instance a histogram could exist on the predicate column and the predicate could match the bucket boundaries or the predicate value could be based on one the values stored in an end biased histogram. However, the optimizer estimate for an Index Seek could be inaccurate. In one embodiment, the method relies on the optimizer for the initial estimate of value N1, but this estimate is refined based on execution feedback. It should be readily apparent that the initial estimate of value N1 can be obtained from a source other than the optimizer. In one embodiment, the method maintains upper bounds and lower bounds of expected cardinality estimates at any point during query execution. The method then refines the estimate of value N1 if it does not lie within these bounds. Progress Estimation of Arbitrary Ouery Plans The method illustrated by FIG. 6 extends to arbitrary query execution plans that include multiple pipelines. One method that estimates the progress of queries with execution plans that include multiple pipelines is illustrated by FIG. 6. In the embodiment illustrated by FIG. 6, the query's execution plan is divided 160 into a set of pipelines. The driver node is identified 162 for each pipeline. Query progress is estimated 164 for each pipeline. The progress of the pipelines is combined 166 to estimate progress of the query. The method illustrated by FIG. 6 is based on the observation that any query execution plan can be viewed as a set of pipelines. Each pipeline can be approximated as a scan of one or more ‘driver’ nodes. By monitoring what percentage of the work done at each driver node is complete, the disclosed method can estimate the overall progress of the query during execution. The method models an arbitrary execution plan as a set of single pipelines and uses estimator PROG for each individual pipeline in an exemplary embodiment. In one embodiment, the method for estimating query progress: (1) defines how to combine estimators for individual pipelines to obtain an estimator for the overall execution plan, (2) identifies pipelines and driver node(s) for each pipeline and initializes the cardinality of each pipeline and (3) refines the cardinality estimates of the driver nodes during query execution. Combining Estimators of Individual Pipelines Given an execution plan, the disclosed method models the query execution plan as a set of pipelines, and approximates each pipeline as a scan of one or more driver nodes. In an exemplary embodiment, the method levies the idea that the total work done is the sum of the work done in individual pipelines. Consider an execution plan in which there are a total of d driver nodes, and suppose the number of tuples that flow out of these nodes (i.e. number of GetNext( ) calls invoked on that node) at the end of query execution are N1 . . . Nd. If we assume each pipeline proceeds at approximately the same rate, then the estimator PROG can be generalized for the entire query plan as follows: PROG = ∑ i = 1 d K i ∑ i = 1 d N i where Ki's denote the current state (number of tuples processed) of the corresponding driver nodes during query execution. In one embodiment, the progress estimator PROG uses the total number of rows observed thus far by all the nodes of the pipeline (denoted Ktotal) and an estimated total number of rows that will be returned by all the nodes of the pipeline (denoted Ntotal). The total number Ktotal of rows observed thus far can be observed during execution of the query. The following example illustrates one way that the total number Ntotal of rows that will be returned can be estimated. Let Kd be the number of rows observed thus far for the driver nodes of the pipeline. In the example, Let Nd be the number of rows estimated for the driver nodes of the pipeline. Let Kd/Nd=f, where f denotes the estimated progress using driver nodes observed at any point during the query's execution. Using a hypothesis that progress estimation using the driver nodes is an accurate estimation of the progress of all the nodes, let Kd/Nd=Ktotal/Ntotal. From this, it follows that Ktotal/Ntotal=f Therefore at any point during the query's execution, we can estimate Ntotal=Ktotal/f. Thus the overall estimator PROG can be written as: PROG=Ktotal (summed up over all pipelines in the tree)/Ntotal (summed up over all pipelines in the tree) where Ntotal for each pipeline is estimated as described above. It should be readily apparent that a variety of other strategies could be employed to estimate total number Ntotal of rows that will be returned. Identifying Pipelines and Driver Nodes Given a starting node of a pipeline, the pipeline is defined as the longest sequence of non-blocking operators from the starting node. Thus all nodes in a pipeline execute together. Of course, the determination of whether or not a node (i.e., physical operator) is blocking depends on the specific operator. For example, an Index Nested Loops join is non-blocking, whereas a Hash Join is blocking. Given an execution plan, the method generates the corresponding set of pipelines by traversing the nodes of the tree in post order and accumulating pipelines using multiple stacks. Referring to FIGS. 5 and 7, given an execution plan, there are two possible kinds of pipelines. FIG. 5 shows a first type of pipeline 150 that is a linear chain of nodes in which there is a unique leaf node 152 that is picked as the driver. Referring to FIG. 7, another possible pipeline 170 comprises multiple input nodes 172 feeding into a single node 174. In the example of FIG. 7, this single node 174 Merge node in a Sort-Merge Join. In this case, all the leaf nodes would be considered driver nodes. When the execution plan of the query is not a single pipeline, the driver nodes are not limited to Table Scan, Index Scan and Index Seek operators. The following examples illustrate some sample execution plans and the corresponding driver nodes. FIG. 8 illustrates dividing a query execution plan 180 into pipelines. Assuming that A is the build side of the Hash Join 182 and B is the probe side, the pipelines are: {Table Scan A 184, Filter 186} 188, {Table Scan B 190, Hash Join 192, Index Nested Loops 194, Index Seek C 196} 198. The driver nodes for the respective pipelines are Table FIG. 9 illustrates the effect of Sort nodes on the progress estimation algorithm. For the query execution plan shown in FIG. 9, the pipelines identified for this query would be {Table Scan A} 200, {Table Scan B} 202 {Sort A, Sort B, Merge Join, Index Nested Loops, Index Seek C} 204 and the driver nodes would be Table Scan A 206, Table Scan B 208, Sort A 210, Sort B 212. Note however, that unlike a Hash Join, for a Sort-Merge Join, the scans of both inputs do need necessarily need to complete for the Sort-Merge Join to complete. Initializing and Refining Driver Node Cardinalities For driver nodes that are leaf nodes (e.g. Table/Index Scans) of the query execution tree, a fairly accurate estimate of cardinality can be obtained from the system catalogs prior to the start of execution of the pipeline. Difficulty arises when cardinality estimates are needed for driver nodes of pipelines that start with non-leaf nodes of the query execution tree (e.g., intermediate Sort nodes and Hash based Group-By nodes). In one embodiment illustrated by FIG. 10, the method relies on the query optimizer to estimate 214 the initial cardinality prior to start of query execution. However, these cardinality estimates can be erroneous. In the embodiment illustrated by FIG. 10, the method identifies 216 errors in the initial estimate and adjusts 218 the estimate accordingly. FIG. 11 illustrates an example of a query execution plan 220. Assuming a hash join is used where A is the build relation and B is the probe relation, the pipelines for the query are {Table Scan A, Filter, Hash Join} 222, {Table Scan B} 224, {Group-By} 226, and {Sort} 228. The driver nodes for the query would include the Sort node. To estimate the cardinality of the Sort operator, the optimizer needs to have accurate estimates on the filter, join and group-by operators. This is the traditional join cardinality estimation problem and distinct value estimation problem for the Group-By operator. As a result, the initial estimate of work done in the Sort 228 could be inaccurate, leading to an inaccurate progress estimation. In an exemplary embodiment, the initial estimates from the optimizer are refined using feedback obtained during query execution. A variety of techniques may be employed to refine the initial estimates from the optimizer. Cardinality estimates can be refined in different ways, depending on where the feedback information is extracted from. An example of one approach for refining the initial estimates is a conservative approach that ensures that inaccuracies are not introduced by the refinement process. In this embodiment, the current estimate Ni of any node is refined only if it is certain that the refinement will make the estimate more accurate. In one embodiment, this is achieved as follows: For each node in the execution plan, the upper and lower bounds UBi and LBi, on the cardinalities of the rows that can be output from a node i. These lower and upper bounds are adjusted as more information is obtained during query execution. The approach monitors whether the current estimate Ni is greater than or equal to the lower bound LBi and less than or equal to the upper bound UBi,. If it is found that the current estimate Ni lies outside the bounds, then the approach corrects the estimate Ni to a value within the bounds. In one embodiment, the value within the bounds is the value of the bound that was violated by the estimate Ni. In one embodiment, the effectiveness of this refinement is increased by quickly refining the bounds based on execution feedback. Refining an upper or lower bound for a particular node could potentially help refine the upper or lower bound of other nodes above the refined node in the execution tree. For example, in FIG. 11, suppose that at some point in time T during the query's execution, it is concluded that conclude that the upper bound for the Hash Join can be reduced from 1 million rows to 0.5 million rows. Suppose the upper bounds for the Group By and Sort nodes were 0.8 million rows. Then, based on the properties of Group-By and Sort nodes, it can also be concluded that each of their upper bounds cannot exceed 0.5 million rows. The lowering of the upper bound could help refine the estimates Ni at one or both of these nodes at time T. Note that even when estimator PROG uses only the driver node cardinalities for progress estimation, it may be useful to refine cardinalities of all nodes in the plan since these estimates could influence the estimates Ni of the driver nodes above it. In one embodiment, these bounds are propagated up the tree as soon as a change in the bound can be made for some node. In one embodiment, the frequency at which such propagation of refinement is done can be limited to control the overhead imposed by the propagation. For example, the bounds could be propagated a few times per second at roughly the granularity at which feedback is necessary to the user for a given application. Refining Uipper and Lower Bounds FIG. 12 illustrates one method of refining upper and lower bounds. In the embodiment illustrated by FIG. 12, each node in the execution tree is modified to keep track 230 of the current number k of tuples output from the operators. Upper and lower bounds are established 231 using the numbers of tuples output from the operators so far. The refinement determines 232 whether the optimizer estimate is within the bounds. If the current optimizer estimate for the node is outside the bounds, the optimizer is updated 234. If the estimate is within the bounds, the estimate is kept 236. This refinement can be applied to any node in the execution tree. In this embodiment, each node in the execution tree maintains upper bounds and lower bounds of expected cardinality estimates at any point during query execution. The optimizer estimate is refined appropriately if the estimate does not lie within these bounds. In one embodiment, the lower and upper bounds are initialized for all leaf nodes of the execution plan prior to query execution. Note that for Table and Index Scan nodes (leaf nodes), both the lower and upper bounds are typically exact and equal to the cardinality of the table (or index). These values can be obtained from system catalogs. The bounds can then be propagated to other nodes in the tree in a bottom up manner using operator specific propagation rules. Table 1, provides examples of propagation rules for refining upper and lower cardinality bounds that can be used for some common physical operators. In Table 1, Ki is the actual number of rows output from the operator thus far, UBi is the upper bound on the number of rows that can be output from the operator and LBi is the lower bound on the number of rows that can be output from the operator. These rules can be extended to include other physical operators. Once query execution begins, depending on the specific operator being executed, if a change in either lower or upper bound is possible for that operator, the bounds are updated for that operator. These bounds can be propagated up the execution plan tree at regular intervals. TABLE 1 Physical Lower Bound Upper Bound Operator i (Lbi) (UBi) Filter Ki (UBi−1 − Ki−1) + Ki Group By D (UBi−1 − Ki−1) + d (# distinct values observed thus far) Sort Ki−1 UBi−1 Nested Loop Ki (UBi−1 − Ki−1) + Ki Join i−1 refers to Outer Relation (Foreign Key) Nested Loop Ki (UBi−1 − Ki−1) · UBi−2 + Ki Join i−2 refers to Inner Relation (Not FK) Hash Join Ki (UBi−1 − Ki−1) · S (Not FK) S is # of rows of largest build partition Table/Index |T| |T| Scan (table T) (# of rows in table) Index Seek Ki |T| (table T) Note that for implementing the rules for certain operators such as Filter, Sort, NL Join (foreign-key) and Index Seek shown in Table 1, the refinement can be done completely at the iterator level. That is, the refinement can be performed without knowledge of how the operator is implemented. In other cases, refinement requires knowledge of how the operator is implemented. For the Group By operator which is blocking, if the number of distinct values d observed during the operator's execution thus far can be counted, then the lower bound can be refined to the number of distinct values d at that point in time. As another example of an operator specific refinement, consider a Hash Join between two relations A (build side) and B (probe side). Assume A has already been hashed into buckets, and suppose S is the number of tuples of the largest bucket. This information can be exploited during the probe phase to obtain a tighter upper bound since it is known that each row from relation B can produce at most S tuples after the join. Thus, by instrumenting operator specific data structures, refinement can be provided for operators like Hash Join and Group-By. In some cases the operator Opi is a Sort operator, which is blocking, and thus starts a new pipeline. In this case, the input to operator Opi would have been consumed while the previous pipeline, involving operator Opi-1, was executing. In this case, when operator Opi starts running, exact cardinality estimates are known for the operator's Opi input. The cardinality of the operator's Opi input is the same as its output, and does not need to be refined further. In one embodiment, the bounds of operator Opi can be refined while the previous operator Opi-1 is running by using the rule in Table 1. It is noted that: (a) Whenever an operator terminates, the upper and lower bounds of that operator are known exactly for the operator and can be propagated to other nodes. (b) Referential integrity constraints that may apply to some nodes (e.g., foreign key constraint applying to ajoin) can be leveraged to obtain tighter bounds. Monotonicity of Progress Bar A progress bar that is monotonically increasing is one where the percentage done does not decrease over time. Monotonicity is a desirable property from a user interface perspective. The ideal estimator I has perfect information of the values Ni and can therefore guarantee monotonicity. However, other techniques can only estimate the values Ni for the driver nodes and hence has to work with uncertainties. For example, the optimizer estimates could be wrong or there could be many runtime factors that cannot be predicted. However, there are conditions under which the disclosed progress estimator can guarantee that the estimates are always increasing with time. A first class of queries where estimator PROG is monotonic is the class of queries where all the driver nodes are table scans or index scans of the execution plan. Since the corresponding values Ni used in the denominator are exact values, the values Ni are guaranteed never to increase. Since the numerator can only increase over time, the estimator PROG is guaranteed to be non-decreasing. For example, the class of queries that can be evaluated using only a pipeline of hash joins would have this property, since none of the intermediate nodes in the plan are driver nodes. Estimator PROG may be monotonic even though one or more intermediate nodes in the execution plan is a driver node. A second class of queries where estimator PROG is monotonic is the class of queries where the estimated cardinalities Ni for the driver nodes are overestimates of the actual cardinality Ni for the nodes. When each estimated cardinality is an overestimate, estimator PROG will be monotonic. Another case where estimator PROG is monotonic is when there are two pipelines P1, P2 and pipeline P1 feeds into pipeline P2. Pipeline P1 has a Table/Index Scan as the driver node and pipeline P2 has a Sort node as the driver node. If pipeline P1 has the property that each row coming out of its driver node can result in at most one row feeding into the Sort node, then estimator PROG will be monotonic. While monotonocity is desirable, it is noted that there is a trade-off between ensuring monotonicity and the accuracy of progress estimation. When the estimated value Ni is an underestimate of the actual value Ni, the progress estimation can become non-monotonic. However, when estimated value Ni is an overestimate of the actual value Ni, monotonicity is not violated. In particular, if the estimated Ni is an upper-bound of the actual value Ni for each node, then monotonicity can be guaranteed. However, it is difficult to find tight upper-bounds so that accuracy of the estimator is not significantly compromised. For example, consider a query plan which performs a hash join of relations R1 and R2 and then sorts the result of the join. The upper-bounds for the scans for R1 and R2 (which are driver nodes) are tight, because the number of rows that will be scanned from each relation is known. However, obtaining a tight upper-bound on the estimate of the Sort node cardinality can be problematic. If the join is a foreign key join, it is known that an upper bound on the cardinality of the joined relation, and hence the Sort node, is the size of table with the foreign-key. Thus, this upper-bound can be used as the estimated value Ni for the Sort node and thereby guarantee monotonicity. However, if the upper-bound is a considerable overestimate of the actual value Ni for the Sort node, the accuracy of the estimator may be poor until most of the query has completed executing. A user may prefer progress estimates that are more accurate or may prefer progress estimates that are guaranteed to be monotonic. In one embodiment, both the estimated progress and the progress based on the upper-bounds (monotonic) are presented to the user. Progress computed using upper bounds is denoted as p1% and the corresponding progress estimate computed using estimates is denoted p2%. The percent done at any instant is not lower than value p1% and the current estimate is the value p2%. Note that value p1% is monotonic, whereas p2% may not be monotonic. Effect of Runtime Conditions The disclosed method models the query as a set of pipelines and approximates each pipeline as a scan of one or more ‘driver’ nodes. If the cardinality of the driver nodes are Ni, the estimator models the total work to be done as ΣiNi. In one embodiment, the disclosed estimator makes the following assumptions: (1) All pipelines and their driver nodes can be computed before the query starts execution. (2) Each pipeline executes at approximately the same rate (i.e., the work done per tuple in each pipeline is approximately the same). Hence the ΣiNi is valid measure of work. In this section, the impact on the accuracy of the estimator when these assumptions do not hold is discussed. In an exemplary embodiment, the estimator PROG is extended to handle such runtime effects. Spills Spills of tuples to disk can occur as a result of insufficient memory and result in more work. As an example, consider a join between two relations A and B, where the optimizer picks a hybrid hash join operator. Hybrid hash proceeds by building a hash table of A in memory. During the scan of relation A, if the memory budget of the hash join is exhausted, then certain buckets will be spilled to disk. When table B is used to probe the hash partitions, the tuples of B that hash to the buckets that are not memory resident are also written to disk. Bucket spilling is a runtime occurrence and hence one cannot predict the number of tuples that will be spilled to disk in advance. Query execution is modeled as comprising two parts to account for spills in one embodiment. One part processes the original relations and the other part processes the spilled partitions. The original query can be modeled as follows: Q=(A join B)∪(A′ join B′) where A′ and B′ denote the corresponding parts of relations A and B that have been spilled (0≦|A′|≦|A|, 0≦|B′|≦|B|). The driver nodes for query Q would include scans of A, B, A′ and B′. Thus the total work for Q would be |A|+|B|+|A′|+|B′|. One complication is that spilled portions |A′|, |B′| cannot be predicted at optimization time. The work (A′ join B′) could be sizable. For instance, consider the point of execution when the first phase of hash execution is over and none of the spilled partitions have been processed. At this point an estimator that ignores spills would estimate progress of (|A|+|B|/|A|+|B|) or 100%, irrespective of the fraction of relations that have been spilled. Another possibility is to assume the worst case and predict that |A′|=|A| and |B′|=|B|. Consider the case where there is sufficient memory to process the join (there are no hash spills), in this case until the hash phase is over, the estimator would always be off by a factor of 2. Thus, both these solutions are unsatisfactory. In an exemplary embodiment, the disclosed method deals with spills as follows. Whenever a tuple is spilled to disk (either from relation A or B) the denominator value (which denotes the total work) is incremented by one. That is, spilling to disk adds more unit of work to be done later and the denominator value is modified (increased) to reflect the expected cardinality of the driver nodes of those pipelines. Consider the point of execution where the first phase of hash processing is over and none of the spilled partitions have been processed. The modified estimator has incremented the denominator counter for each tuple that had been spilled and would estimate the progress as (|A|+|B|)/(|A|+|B|+|A′|+|B′|) which is correct as it accounts for the remaining tuples to be processed. When the spilled partitions are re-read the corresponding counts would be counted in the numerator and only when all the partitions have been processed will the estimator report the progress as 100%. This correction to the estimator works because of the symmetry of spills, i.e., exactly the same number of tuples that have been written to disk will be processed later. This modification to the original algorithm can be used for multiple recursion levels in a hash join pipeline. Spills could occur in other operators like hash-based Group-By or the merge phase in a Sort-Merge join if there are too many duplicates of a particular value. In general, a query can be considered as Q∪Q′ where Q′ accounts for the work done by the current query in handling data that is spilled. The estimator starts with the driver node counts for only Q, as query execution proceeds it keeps track of the work to be performed on Q′ by incrementing the total work suitably whenever any tuple is spilled to disk from any operator from the query. Non-Uniform Execution Rates Across Pipelines In one embodiment weights C are assigned to pipelines to account for non-uniform execution rates of pipelines that make up the query. In the embodiment, described above, an assumption of the estimator PROG was that all pipelines of the query execute at approximately the same rate. When this is the case, the sum of the expected cardinalities of the driver nodes is an accurate measure of work. But in certain cases, pipelines within the same execution plan could have widely varying execution rates. This could occur for the following reasons: (1) The number of operators could widely vary between pipelines. (2) Certain pipelines could have more expensive operators. (3) The portion of data touched by a particular pipeline could be read from a much slower disk or could be read entirely from the buffer pool, which could change the rate of execution drastically. To deal with this problem, the PROG estimator is extended as follows in one embodiment. In this embodiment, let the cardinality estimates for the d driver nodes in the execution plan be Ni (i=1 . . . d). Let Ci denote the relative per-tuple work of each pipeline. Then the progress would be reported as: PROG = ∑ i C i . K i ∑ i C i . N i In the case where all pipelines proceed at the same rate (i.e. Ci=1) the estimator PROG is unchanged. One complication is that the relative per-tuple work Ci values are not known until execution time. In one embodiment, the method starts with uniform relative rates (i.e. Ci=1 for all i) and adjusts the relative weights based on execution feedback. That is, the per-tuple cost Ci for each pipeline is adjusted as execution proceeds. Leveraged Technology Two existing technologies are leveraged to estimate query progress in an exemplary embodiment. The first technology is estimating cardinality of query expressions. Selectivity estimation and distinct value estimation enable query optimizers to pick a suitable query execution plan. In the exemplary embodiment, the estimator leverages cardinality estimation techniques used by the query optimizer to provide an initial estimates of cardinality of driver nodes in a pipeline. The second technology is the use of information gathered during query execution. In an exemplary embodiment, the progress estimator uses observed cardinality of operators in the execution tree to improve estimate of total work that needs to be done, while leaving the query execution plan unchanged. A second use of such information is to improve selectivity estimation of subsequent queries. In an exemplary embodiment, a progress bar is provided for arbitrary queries, such as arbitrary SQL queries. Providing a progress bar for arbitrary requires the total work required to execute a query to be accurately estimated. Queries in modern database systems are quite complex involving joins, nested sub-queries and aggregation. In the exemplary embodiments, the model of work used is not completely independent of the intermediate cardinalities of join, nested sub-query and aggregation operators, because a measure of work that is independent of such operators is likely to be too simplistic. For instance, a progress estimator that reports what fraction of nodes in the execution tree that have completed would be too simplistic. If a query is just a single pipeline of operators, for almost the entire duration of the execution of the query, all the operators are active. Thus, this strategy that bases the progress on number of operators that have completed, will not report any progress until near the very end of query execution. In an exemplary embodiment, the method deals with blocking operators. Assuming that an optimizer can predict the number of query results accurately at the start of query execution, a progress estimator that reports the fraction of query results that have been returned could still be very inaccurate. For example, in a pipeline of a number N of hash joins (which are blocking), the query results are not computed until the probe phase of the last hash join starts. Therefore, until that time, a progress estimator that reports the fraction of query results that have been returned would not report any progress irrespective of the number of joins executed. The method illustrated by FIG. 6 is based on the observation that any query execution plan can be viewed as a set of pipelines. Each pipeline can be approximated as a scan of one or more ‘driver’ nodes. By monitoring what percentage of the work done at each driver node is complete, the disclosed method can estimate the overall progress of the query during execution. The disclosed methods use a model for the total work done by a long running query and uses an estimator for the percentage of the query's work that has completed. This functionality is useful in today's database systems. One advantage of the disclosed progress estimation methods is that they are easy to implement in typical query processing engines that follow the iterator model. Another benefit of the disclosed progress estimation methods is that they are applicable to general SQL since the method deals with the execution plan level. Exemplary Operating Environment FIG. 9 and the following discussion are intended to provide a brief, general description of a suitable computing environment in which the invention may be implemented. Although not required, the invention will be described in the general context of computer-executable instructions, such as program modules, being executed by a personal computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. With reference to FIG. 9, an exemplary system for implementing the invention includes a general purpose computing device in the form of a conventional personal computer 20, including a processing unit 21, a system memory 22, and a system bus 24 that couples various system components including system memory 22 to processing unit 21. System bus 23 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. System memory 22 includes read only memory (ROM) 24 and random access memory (RAM) 25. A basic input/output system (BIOS) 26, containing the basic routines that help to transfer information between elements within personal computer 20, such as during start-up, is stored in ROM 24. Personal computer 20 further includes a hard disk drive 27 for reading from and writing to a hard disk, a magnetic disk drive 28 for reading from or writing to a removable magnetic disk 29 and an optical disk drive 30 for reading from or writing to a removable optical disk 31 such as a CD ROM or other optical media. Hard disk drive 27, magnetic disk drive 28, and optical disk drive 30 are connected to system bus 23 by a hard disk drive interface 32, a magnetic disk drive interface 33, and an optical drive interface 34, respectively. The drives and their associated computer-readable media provide nonvolatile storage of computer-readable instructions, data structures, program modules and other data for personal computer 20. Although the exemplary environment described herein employs a hard disk 27, a removable magnetic disk 29 and a removable optical disk 31, it should be appreciated by those skilled in the art that other types of computer-readable media which can store data that is accessible by computer, such as random access memories (RAMs), read only memories (ROMs), and the like may also be used in the exemplary operating environment. A number of program modules may be stored on the hard disk 27, magnetic disk 29, optical disk 31, ROM 24 or RAM 25, including an operating system 35, one or more application programs 36, other program modules 37, and program data 38. A database system 55 may also be stored on the hard disk, magnetic disk 29, optical disk 31, ROM 24 or RAM 25. A user may enter commands and information into personal computer 20 through input devices such as a keyboard 40 and pointing device 42. Other input devices may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to processing unit 21 through a serial port interface 46 that is coupled to system bus 23, but may be connected by other interfaces, such as a parallel port, game port or a universal serial bus (USB). A monitor 47 or other type of display device is also connected to system bus 23 via an interface, such as a video adapter 48. In addition to the monitor, personal computers typically include other peripheral output devices such as speakers and printers. Personal computer 20 may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer 49. Remote computer 49 may be another personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to personal computer 20, although only a memory storage device 50 has been illustrated in FIG. 9. The logical connections depicted in FIG. 9 include local area network (LAN) 51 and a widearea network (WAN) 52. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet. When using a LAN networking environment, personal computer 20 is connected to local network 51 through a network interface or adapter 53. When used in a WAN networking environment, personal computer 20 typically includes a modem 54 or other devices for establishing communication over wide area network 52, such as the Internet. Modem 54, which may be internal or external, is connected to system bus 23 via serial port interface 46. In a networked environment, program modules depicted relative to personal computer 20, or portions thereof, may be stored in remote memory storage device 50. It will be appreciated that the network connections shown are exemplary and other ways of establishing a communications link between the computers may be used. | <SOH> FIELD OF THE INVENTION <EOH>The present invention concerns a method of estimating the progress of queries executed on a database. | <SOH> SUMMARY <EOH>The present disclosure concerns a query progress indicator that provides an indication to a user of the progress of a query being executed on a database. The indication of the progress of the query allows the user to decide whether the query should be allowed to complete or should be aborted. One method that may be used to estimate the progress of a query that is being executed on a database defines a model of work performed during execution of a query. The total amount of work that will be performed during execution of the query is estimated according to the model. The amount of work performed at a given point during execution of the query is estimated according to the model. The progress of the query is estimated using the estimated amount of work performed up to the given point and the estimated total amount of work. This estimated progress of query execution can be provided to the user. The work performed during execution of the query may be modeled in a variety of ways. For example, work performed during execution of a query could be modeled as a number items returned, such as tuples or groups returned, or a number of GetNext( ) calls. In one embodiment, the work performed during execution of the query is approximated as the work performed by a subset of operators of the query. For example, the work performed during execution of the query could be modeled as work performed by one or more driver node operators during execution of the query. In one embodiment, a query execution plan is divided into a set of pipelines, the progress of each pipeline is estimated, and the estimates from the pipelines are combined and returned as the progress of the query. The pipelines comprise sequences of non-blocking operators. In one embodiment, the total amount of work that will be performed by a pipeline is initialized with an estimate from a query optimizer or another source. In one embodiment, the initial estimate of total work is be refined using feedback obtained during query execution. For example, the total work can be refined by maintaining upper and lower bounds on the total work that will be performed. The initial estimate is then refined when it violates the upper or lower bound. Upper and lower bounds may be maintained for each of the operators in each pipeline with bound defining rules for each different type of operator. In one embodiment, the upper and lower bounds are defined in terms of a number of items returned so far by the query operator, the number of items returned so far by one or more preceding query operators, and/or the upper and/or lower bounds of one or more preceding operators. In one embodiment, changes in bounds of query operators are periodically propagated up the query execution plan to allow the bounds of following query operators in the execution plan to be updated. In one embodiment, driver node operators are identified for each pipeline. In this embodiment, the work performed during execution of the pipelines is modeled as work performed by the driver node operators. In one embodiment, weights are assigned to the pipelines that make up the query. These weights may be based on relative execution rates of the pipelines. In one embodiment, the method identifies a spill of tuples to disk during query execution. The model of work may be adjusted to account for additional work that results from the spill of tuples and/or an indicator may be provided that alerts the user that the spill has occurred. In one embodiment, computer readable instructions for performing a method for estimating query progress are stored on computer readable media. The computer readable instructions can be stored in a memory of a system for providing an indication of query progress. Such a system includes a user input device, a display, a data content, and a processor. The user input device enables a user to begin execution of a query and abort execution of a query. The processor is coupled to the user input device, to the display, to the data content, and to the memory. The processor executes the machine instructions to execute a query upon the data content, monitor progress of the query, and provide an indicator of query progress on the display. In one embodiment, the query progress indicator provides a visual indication of a percentage of query execution that has been completed. In one embodiment, decreasing progress estimations are prevented from being displayed. These and other objects, advantages, and features of an exemplary embodiment are described in conjunction with the accompanying drawings. | 20040331 | 20090217 | 20051006 | 58587.0 | 0 | HICKS, MICHAEL J | QUERY PROGRESS ESTIMATION | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,031 | ACCEPTED | NON-INTRUSIVE PRESSURE SENSING DEVICE | A none intrusive pressure sensing device that clamps on to a pressure line and detects the internal pressure of the pressure line by detecting the resultant changes in the diameter of the pressure line. The clamp is held together by a fastener having a sensing element, such as a strain gage, that is able to detect the change in length of the fastener as the pressure line and the clamp expand and contract with the internal pressure of the pressure line. | 1. A non-intrusive pressure transducer for detecting a pressure in a pressure line, the pressure line having an inner diameter and an outer diameter, the pressure transducer comprising: a clamping cuff including a first arm having a first arm first end and a first arm second end, a second arm having a second arm first end and a second arm second end, the first and second arms being joined at the first portion first end and the second portion first end; a sensor fastener for connecting the first arm second end and the second arm second end such that the first cuff and the second cuff fit snugly over the outer diameter of the pressure line to form a clamping cuff assembly, the sensor fastener having a diameter and comprising at least one attached strain gage, the clamping cuff assembly expanding and contracting as the pressure line expands and contracts, the pressure line expanding and contracting as the pressure increases and decreases, a length of the sensor fastener changing as the clamping cuff assembly expands and contracts, the at least one strain gage detecting the length of the sensor fastener. 2. The non-intrusive pressure transducer of claim 1, wherein the sensor fastener is tensile. 3. The non-intrusive pressure transducer of claim 1, wherein the sensor fastener is compressive. 4. The non-intrusive pressure transducer of claim 1, wherein the at least one strain gage comprises four strain gages equally spaced over the diameter of the sensor fastener. 5. The non-intrusive pressure transducer of claim 1, wherein the sensor fastener comprises a load cell. 6. The non-intrusive pressure transducer of claim 1, wherein at least one of the first arm and the second arm comprises a flexible portion of high tensile strength. 7. The non-intrusive pressure transducer of claim 6, wherein the flexible portion is formed from chainmail. 8. A method of detecting a pressure in a pressure line with a non-intrusive pressure transducer, the pressure transducer including a clamping cuff and a sensor fastener, the clamping cuff including: including a first arm having a first arm first end and a first arm second end, a second arm having a second arm first end and a second arm second end, the first and second cuff arms being joined at the first arm first end and the second arm first end; and a sensor fastener to connect the first arm second end and the second arm second end, the sensor fastener including at least one attached strain gage, the method comprising: attaching the clamping cuff to the pressure line by fitting the first and second arms about the outer diameter of the pressure line; connecting the first arm second end and the second arm second end with the sensor fastener to form a clamping cuff assembly; allowing the clamping cuff assembly to expand and contract as the pressure increases and decreases and the pressure line expands and contracts accordingly, a length of the sensor fastener changing as the clamping cuff assembly expands and contracts; detecting the length of the sensor fastener via the at least one strain gage; and | FIELD OF THE INVENTION The invention relates to pressure sensors and, more particularly, relates to non-intrusive devices for detecting pressures of a pressurized fluid or gas in a pressure line without breaching a wall of the pressure line or contacting the fluid or gas inside the pressure line. BACKGROUND OF THE INVENTION Most conventional pressure transducers used to detect pressures in the pressure lines of machinery are intrusive, requiring exposure to the pressurized fluid or gas in the pressure line. This involves an assembly process requiring a breach in the wall of the pressure line or some other method of direct exposure of the pressure transducer to the pressurized fluid or gas. SUMMARY OF THE INVENTION The assembly processes for the intrusive transducers tend to increase assembly and maintenance costs for the machinery and to increase the potential for contamination of the fluid or gas. The complexity of some of the conventional non-intrusive pressure transducers tends to be costly and to make such transducers difficult to fabricate. The bulkiness of a remainder of the conventional non-intrusive pressure transducers tends to decrease the range of use, especially in machinery where space is at a premium. Described herein is a device and method for non-intrusively detecting an internal pressure of a pressure line. A clamp with two arms is closed over the outer diameter of the pressure line for a snug fit having first ends of the clamp arms pivotally connected and second ends of the clamp arms connected by a sensor fastener. As the internal pressure in the pressure line increases and decreases, the outer diameter of the pressure line expands and contracts causing a diameter of the clamp to expand and contract and the length of the sensor fastener to change. The sensor fastener includes a sensing element that detects the length of the sensor fastener as it changes with the pressure. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described in detail, with references to the following figures, wherein: FIG. 1 is a side view of an exemplary embodiment of the clamping cuff assembly of the invention; FIG. 2 is a front view of the clamping cuff assembly of FIG. 1; FIG. 3 is a top view of the clamping cuff assembly of FIG. 1; FIG. 4 is an exploded view of the clamping cuff assembly of FIG. 1; FIG. 5 is a view of an exemplary embodiment of a sensor fastener; FIG. 6 is a side view of a second embodiment of the clamping cuff assembly of the invention; FIG. 7 is a front view of the clamping cuff assembly of FIG. 6; FIG. 8 is a top view of the clamping cuff assembly of Fib. 6; FIG. 9 is a side view of a third embodiment of the clamping cuff assembly of the invention; FIG. 10 is a top view of the clamping cuff assembly of FIG. 9; and FIG. 11 is a functional diagram illustrating the connections between strain gages, a controller and a display. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a side view of an exemplary embodiment of the clamping cuff assembly of the invention. As illustrated in FIG. 1 as well as FIGS. 2-4, the clamping cuff assembly includes a clamping cuff 10 and a sensor fastener 20. The clamping cuff 10 includes: a first arm 11 having a first arm first end 11 a and a first arm second end 11b; a second arm 12 having a second arm first end 12a and a second arm second end 12b; a bolt 13 and a nut 14. The nut 14 and bolt 13 pivotally connect the first arm 11 and the second arm 12 via holes 11c and 12c in the first arm first end 11a and the second arm first end 12a, respectively, as illustrated in FIGS. 1-4. The first arm and second arms 11, 12 are made of strong and relatively rigid materials. These materials include, but are not limited to, aluminum and steel. As illustrated in FIG. 5, the sensor fastener 20 includes four strain gages 21a-21d, a nut 22 and a bolt 23 having a threaded portion 23a, a shank 23b and a head 23c. The nut 22 is a conventional locking nut. The four strain gages 21a-21d are attached at equal angular positions around the circumference of the shank 23b. The strain gages 21a-21d are then electrically connected to a conventional measuring device or controller 50 for receiving signals from the strain gages 21a-21d, converting those signals to read in units of pressure, and displaying the converted results on a display 40 as illustrated in FIG. 11. In operation, the first and second cuff arms 11, 12 are placed around the pressure line 30. The first arm second end 11b and the second arm second end 12b are then connected via the sensor fastener 20, slot 11d and slot 12d as illustrated in FIGS. 1-4. Finally the sensor fastener 20 is tightened, i.e., pre-loaded in tension for a snug fit between the pressure line 30 and the cuff assembly 10. As the pressure line 30 expands and contracts with increasing and decreasing internal pressure, the shank 23b lengthens and shortens accordingly as the sensor fastener 20 holds the cuff assembly 10 together via tension. Thus, the strain gages 21a-21d detect any changes in a length of the sensor fastener 20 as they, i.e., the strain gages 21a-21d, lengthen and shorten in concert with the shank 23b. FIG. 6 is a side view of a second embodiment of the clamping cuff assembly of the invention comprising: a first arm 111 having a first arm first end 111a and a first arm second end 111b; a second arm 112 having a second arm first end 112a and a second arm second end 112b; and a sensor fastener 120 including two nuts 122a, 122b, a screw 123, and four strain gages 121a-121d. The first arm second end 111b includes a slot 111d and the second arm second end 112b includes a hole 112d. The screw 123 includes a first connecting portion 123a, a second connecting portion 123b and a shank 123c. All other components remain the same as in the first embodiment. As illustrated in FIGS. 6 and 7, in this particular embodiment the first arm second end 111 and the second arm second end 112 extend past each other. Thus, in the second embodiment of the invention, the sensor fastener 120 is compressive as it holds the clamping cuff assembly 100 together via a compressive load. The compressive nature of the sensor fastener 120 is the primary functional difference between the first and second embodiments of the invention. The pivotal connection between the first arm first end 111a and the second arm first end 112a is established after the first arm 111 and the second arm 112 are placed in position about the pressure line 30 to avoid interference between the first arm second end 111b and the second arm second end 112b. In operation the first and second arms 111, 112 of the clamping cuff 100 are placed around the pressure line 30 and held in place by assembling the sensor fastener 120 as illustrated in FIGS. 6 and 7. The first arm first end 111a and the second arm first end 112a are then pivotally connected via the holes 111c and 112c using the nut 14 and the bolt 13. Finally, as indicated in FIG. 6, the sensor fastener 120 is assembled by: placing the first connecting portion 120a into the hole 112d; sliding the second connecting portion into the slot 111c such that nuts 122a and 122b are on opposite sides of the slot 111d; and adjusting the nuts 122a and 122b for a frictional connection to the opposite sides of the slot 111d as well as a compressive pre-load on the shank 120c. The sensor fastener 120 then, respectively, shortens and lengthens as the clamp 100 expands and contracts with the internal pressure of the pressure line 30. FIG. 9 illustrates a third exemplary embodiment of the invention. This embodiment is essentially the same as the first embodiment illustrated in FIG. 1. However in this embodiment the clamp 200 comprises a first flexible arm 211 with a first arm first end 211a and a first arm second end 211b; a second flexible arm 212 with a second arm first end 212a, and a second arm second end 212b. In this particular embodiment, the first ends 211a, 212a are directly joined and indistinguishable from each other as the first and second flexible arms comprise a single and continuous piece of flexible material. The flexible material may include, but is not limited to, nylon and leather. Having described the illustrated embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>Most conventional pressure transducers used to detect pressures in the pressure lines of machinery are intrusive, requiring exposure to the pressurized fluid or gas in the pressure line. This involves an assembly process requiring a breach in the wall of the pressure line or some other method of direct exposure of the pressure transducer to the pressurized fluid or gas. | <SOH> SUMMARY OF THE INVENTION <EOH>The assembly processes for the intrusive transducers tend to increase assembly and maintenance costs for the machinery and to increase the potential for contamination of the fluid or gas. The complexity of some of the conventional non-intrusive pressure transducers tends to be costly and to make such transducers difficult to fabricate. The bulkiness of a remainder of the conventional non-intrusive pressure transducers tends to decrease the range of use, especially in machinery where space is at a premium. Described herein is a device and method for non-intrusively detecting an internal pressure of a pressure line. A clamp with two arms is closed over the outer diameter of the pressure line for a snug fit having first ends of the clamp arms pivotally connected and second ends of the clamp arms connected by a sensor fastener. As the internal pressure in the pressure line increases and decreases, the outer diameter of the pressure line expands and contracts causing a diameter of the clamp to expand and contract and the length of the sensor fastener to change. The sensor fastener includes a sensing element that detects the length of the sensor fastener as it changes with the pressure. | 20040331 | 20060822 | 20051027 | 67577.0 | 0 | OEN, WILLIAM L | NON-INTRUSIVE PRESSURE SENSING DEVICE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,146 | ACCEPTED | Apparatus and method for detecting position of mobile robot | An apparatus and a method for detecting a position of a mobile robot in accordance with the present invention can accurately detect a position of a mobile robot by calculating time taken for each ultrasonic signal generated by ultrasonic signal oscillating means of a charging station to reach the mobile robot on the basis of a point of time at which an RF (Radio Frequency) signal emitted from the mobile robot is generated; calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance value between the ultrasonic signal oscillating means. | 1. A method for detecting a position of a mobile robot comprising: calculating time taken for each ultrasonic signal generated by ultrasonic signal generated means of a charging station to reach the mobile robot on the basis of a point of time at which a radio frequency (RF) emitted from the mobile robot is emitted, and calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance value between the ultrasonic signal oscillating means. 2. The method of claim 1, wherein the angle between the charging station and the mobile robot is calculated through triangulation based on the calculated distance value and the preset distance value between the ultrasonic signal oscillating means. 3. The method of claim 1, wherein the RF signal is emitted at preset time intervals. 4. The method of claim 1, further comprising prestoring a position number for discriminating a position of at least one ultrasonic means for receiving the ultrasonic signals, in order to detect a direction that the mobile robot proceeds. 5. The method of claim 1, further comprising adding a semidiameter of the mobile robot to the distance value between the charging station and the mobile robot. 6. The method of claim 1, wherein the distance value between the charging station and the mobile robot is detected through expression S=340[m/sec]×(T1−T2), wherein 340[m/sec] is sound velocity, T1 is time taken to receive an ultrasonic signal, and T2 is time taken to oscillate an ultrasonic signal after receiving an RF signal. 7. An apparatus for detecting a position of a mobile robot generates an RF (Radio Frequency) signal and ultrasonic signals, calculates reaching time taken for each ultrasonic signal to reach the mobile robot on the basis of a point of time at which the RF signal is generated and detects a position of the mobile robot based on the reaching time and a preset distance value between the ultrasonic signal oscillating means for oscillating the ultrasonic signals. 8. An apparatus for detecting a position of a mobile robot comprising: an RF generating means installed at a mobile robot and for emitting an RF (Radio Frequency) signal; an RF reception means installed at a charging station and for receiving the RF signal emitted by the RF generating means; ultrasonic signal oscillating means each installed at the charging station and for oscillating ultrasonic signals; a control means for controlling the ultrasonic signal oscillating means so that the ultrasonic signals are oscillated whenever the RF signal is received by the RF reception means; ultrasonic signal reception means installed on an outer circumferential surface of the mobile robot and for receiving the ultrasonic signals oscillated by the ultrasonic signal oscillating means; and a microcomputer installed in the mobile robot and for calculating a distance and an angle between the mobile robot and the charging station based on reaching time taken for each ultrasonic signals to reach the mobile robot and a preset distance value between the ultrasonic signals oscillating means. 9. The apparatus of claim 8, wherein the microcomputer compensates a position error of the mobile robot by checking the position of the mobile robot based on the calculated distance value and angle value. 10. The apparatus of claim 8, wherein the ultrasonic signal oscillating means are installed to be symmetric to each other in a horizontal direction of the charging station. 11. The apparatus of claim 8, wherein the ultrasonic signal oscillating means are installed to be symmetric to each other in vertical and horizontal directions at the charging station. 12. The apparatus of claim 8, wherein the microcomputer detects reaching time taken for each ultrasonic signal to be received by one or more ultrasonic signal reception means after being oscillated by the ultrasonic signal oscillating means on the basis of a point of time at which an RF signal, which is generated at preset time intervals, is generated; calculates a distance between the mobile robot and the charging station based on the detected reaching time; and calculates an angle between the mobile robot and the charging station through triangulation based on the detected reaching time and the preset distance value between the ultrasonic signal oscillating means. 13. The apparatus of claim 8, wherein the microcomputer further comprises a storing means for storing position numbers for discriminating positions of the ultrasonic signal reception means, and detects a direction that the mobile robot proceeds through the position number of the ultrasonic signal reception means which has received the ultrasonic signal. 14. The apparatus of claim 8, wherein when the ultrasonic signals are is received by two or more ultrasonic reception means, the microcomputer calculates reaching time taken for each ultrasonic signal to be received by the two or more ultrasonic signal reception means; selects two ultrasonic signal reception means which have received ultrasonic signals whose reaching time is the fastest, among the calculated reaching time values; and calculates a distance between the mobile robot and the charging station based on the reaching time of the ultrasonic signals which have been received by the two selected ultrasonic signal reception means. 15. The apparatus of claim 8, wherein the microcomputer detects the distance between the charging station and the mobile robot through expression S=340[m/sec]×(T1−T2), wherein 340[m/sec] is sound velocity, T1 is time taken to receive an ultrasonic signal, and T2 is time taken to oscillate an ultrasonic signal after receiving an RF signal. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile robot, and particularly, to an apparatus and a method for detecting a position of a mobile robot. 2. Description of the Background Art In general, a mobile robot, particularly, a robot cleaner is a device for automatically cleaning an area to be cleaned by sucking foreign substances such as dust or the like on a floor, while automatically moving along a wall surface of a room (e.g., living room, inner room or the like) of a private home without an operation of a user. The robot cleaner discriminates a distance between itself and an obstacle installed in a cleaning area, such as furniture, office supplies, a wall or the like, through a distance sensor, and selectively drives a motor for driving its left wheel and a motor for driving its right wheel depending on the discriminated distance, so that the robot cleaner automatically switches its direction to clean the cleaning area. Herein, the robot cleaner performs cleaning, moving in the cleaning area through map information stored in an internal storing device. Hereinafter, a mapping operation for generating the map information will now be described. First, the robot cleaner moves along a side surface of an operation space (e.g., wall surface of living room in private home), to calculate a distance and a direction between itself and a charging station installed on a wall, and determines its position based on the calculated distance value and direction value, to scan the operation space. Herein, the robot cleaner detects its current position by using an encoder installed at its wheel. The robot cleaner determines whether there is an obstacle between itself and the charging station. If there is no obstacle, the robot cleaner transmits/receives a signal to/from the charging station to scan an operation space. On the contrary, if there is an obstacle between the robot cleaner and the charging station, the robot cleaner scans another operation space first, and then, when the obstacle is eliminated, it transmits/receives a signal to/from the charging station to scan the operation space where the obstacle has eliminated. However, in the method of detecting a position of the robot cleaner by using the encoder, since the current position of the robot cleaner is searched using the encoder installed at the wheel, an error occurs by sliding of the wheel or an idle rotation. As another method for detecting a position of a robot cleaner in accordance with another conventional art, stickers or reflection plates with the same shapes are attached to an operation space (e.g., wall surface of living room of private home) at prescribed intervals, and the robot cleaner recognizes the sticker or the reflection plate by using a CCD camera to thereby compensate an error occurring by sliding of the wheel or an idle rotation, so that the robot cleaner recognizes a distance between itself and the charging station. However, in this method of detecting a position of the robot cleaner by using the sticker or the reflection plate, when illumination brightness of a cleaning area is changed or a subject having a shape similar to the sticker or the reflection plate is recognized, a distance error may be accumulated. In addition, when illumination brightness is higher or lower than a threshold, a CCD (charge-coupled device) camera cannot recognize the sticker or the reflection plate, and thus the robot cleaner cannot check its position. In addition, since the CCD cameral has to be attached to the robot cleaner, fabrication cost of the robot cleaner is increased. Techniques for a robot cleaner in accordance with conventional arts are also disposed in U.S. Pat. No. 5,440,216 and U.S. Pat. No. 5,646,494. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an apparatus and a method for detecting a position of a mobile robot capable of accurately detecting a position of the mobile robot by calculating reaching time taken for each ultrasonic signal to be received by the mobile robot after being oscillated by ultrasonic signal oscillating means of a charging station on the basis of an RF (radio frequency) signal emitted at certain time intervals and a distance value between the ultrasonic signal oscillating means and thus by detecting a position of the mobile robot based on the calculated values. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for detecting a position of a mobile robot comprising: calculating time taken for each ultrasonic signal generated by ultrasonic signal generated means of a charging station to reach the mobile robot on the basis of a point of time at which a RF (Radio Frequency) emitted from the mobile robot is emitted, and calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance value between the ultrasonic signal oscillating means. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for detecting a position of a mobile robot generating an RF (Radio Frequency) signal and ultrasonic signals, calculating reaching time taken for each ultrasonic signal to reach the mobile robot on the basis of a point of time at which the RF signal is generated, and detecting a position of the mobile robot based on the reaching time and a preset distance value between the ultrasonic signal oscillating means for oscillating the ultrasonic signals. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for detecting a position of a mobile robot comprising: an RF generating means installed at a mobile robot and for emitting an RF (Radio Frequency) signal; an RF reception means installed at a charging station and for receiving the RF signal emitted by the RF generating means; ultrasonic signal oscillating means each installed at the charging station and for oscillating ultrasonic signals; a control means for controlling the ultrasonic signal oscillating means so that the ultrasonic signals are oscillated whenever the RF signal is received by the RF reception means; ultrasonic signal reception means installed on an outer circumferential surface of the mobile robot and for receiving the ultrasonic signals oscillated by the ultrasonic signal oscillating means; and a microcomputer installed in the mobile robot and for calculating a distance and an angle between the mobile robot and the charging station based on reaching time taken for each ultrasonic signal to reach the mobile robot and a preset distance value between the ultrasonic signals oscillating means. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a unit of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: FIG. 1 is a block diagram showing a construction of an apparatus for detecting a position of a mobile robot in accordance with an embodiment of the present invention; FIG. 2 is a flow chart of a method for detecting a position of mobile robot in accordance with an embodiment of the present invention; and FIG. 3 is a schematic view showing a process of calculating a distance and an angle between a mobile robot and a charging station in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of an apparatus and a method for detecting a position of a mobile robot capable of accurately detecting a position of the mobile robot by calculating time taken for each ultrasonic signal generated by ultrasonic signal oscillating means of a charging station to reach the mobile robot, on the basis of a point of time at which an RF signal (Radio Frequency signal) is generated; calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance values between the ultrasonic signal oscillating means, will now be described in detail with reference to FIGS. 1 through 3. FIG. 1 is a block diagram showing a construction of an apparatus for detecting a position of a mobile robot in accordance with an embodiment of the present invention. As shown therein, an apparatus for detecting a position of a mobile robot in accordance with an embodiment of the present invention includes: an RF generating means 1 installed at a prescribed position of a mobile robot and for emitting an RF signal (radio frequency signal) for detecting a position of the mobile robot at certain time intervals; an RF reception means 2 installed at a prescribed position of a charging station fixed on a place such as a wall surface of a private home and for receiving the RF signal emitted by the RF generating means 1; first and second ultrasonic signal oscillating means 3, 4 each installed at a prescribed position of the charging station and for sequentially oscillating first and second ultrasonic signals for calculating a distance and an angle between the mobile robot and the charging station; a control means 5 installed at a prescribed position of the charging station and for controlling the first and second ultrasonic signal oscillating means 3, 4 so that the first and second ultrasonic signals are sequentially oscillated whenever the RF signal is received by the RF reception means 2; a plurality of ultrasonic signal reception means (Rx1˜Rxn) installed on an outer circumferential surface of the mobile robot at certain intervals therebetween and for sequentially receiving the first and second ultrasonic signals oscillated by the first and second oscillating means 3, 4; a microcomputer 6 installed inside the mobile robot and for calculating a distance and an angle between the mobile robot and the charging station based on reaching time of each of first and second ultrasonic signals and a preset distance value between the first and second ultrasonic signal oscillating means 3, 4; and a memory 7 for storing position numbers for discriminating the positions of the plurality of ultrasonic signal reception means (Rx1˜Rxn) and the preset distance value between the first and second ultrasonic signal oscillating means 3, 4. Hereinafter, operations of the apparatus for detecting a position of the mobile robot in accordance with an embodiment of the present invention will now be described. First, when the mobile robot moving in a cleaning area along a preset moving pattern, the microcomputer 6 controls the RF generating means 1 in order to detect positions of the mobile robot at preset time intervals. The RF generating means 1 generates an RF signal for detecting positions of the mobile robot at preset time intervals (e.g., at 3-second intervals) under the control of the microcomputer 6, and emits the generated RF signal. The RF reception means 2 positioned at the charging station receives the RF signal and outputs a first notifying signal for notifying that the RF signal has been received, to the control means 5 positioned at the charging station. At this time, the control means 5 controls the first and second ultrasonic signal oscillating means 3, 4, at preset time intervals based on the first notifying signal. The first and second ultrasonic signal oscillating means 3, 4 sequentially oscillate first and second ultrasonic signals under the control of the control means 5. Herein, a plurality of first and second ultrasonic signal oscillating means may be installed and also the plurality of first and second ultrasonic signal oscillating means may be installed at prescribed positions of the charging station to be symmetric to each other in a horizontal direction or may be installed at prescribed positions of the charging station to be symmetric to each other in vertical and horizontal directions. The charging station is fixedly installed on a wall surface of a private home or the like in order to charge a battery (not shown) of the mobile robot. Thereafter, the plurality of ultrasonic signal reception means (Rx1˜Rxn) installed at the mobile robot receives the sequentially-oscillated first and second ultrasonic signals and outputs a second notifying signal for notifying that the first and second ultrasonic signals have been received, to the microcomputer 6. Based on the second notifying signal the microcomputer 6 calculates the time taken for each of first and second ultrasonic signals to reach one or more ultrasonic signal reception means (Rx1˜Rxn) after being oscillated by the ultrasonic signal oscillating means 3, 4. Then, the microcomputer 6 calculates a distance and an angle between the mobile robot and the charging station based on the calculated reaching time and a preset distance value between the first and second ultrasonic signal oscillating means 3, 4, thereby detecting a current position of the mobile robot. Then, the microcomputer 6 compensates a current position error of the mobile robot based on the detected position value. In addition, the microcomputer 6 checks positions of the ultrasonic signal reception means (e.g., Rx1, Rx2) which have received the first and second ultrasonic signals, among the plurality of ultrasonic signal reception means (Rx1˜Rxn), by discriminating the pertinent ultrasonic signal reception means through the position numbers prestored in the memory 7. That is, the microcomputer 6 detects a direction that the mobile robot proceeds through the preset position number of the ultrasonic signal reception means which has received an ultrasonic signal. For example, an outer shape of the mobile robot is round, the rear of the mobile robot (opposite direction that the mobile robot proceeds) is zero degree, a first ultrasonic signal reception means (Rx1) is installed at a position of zero degree, and a second ultrasonic signal reception means (Rx2) is installed at a position apart from the first ultrasonic signal reception means at an interval of 30 degrees therebetween. That is, the first and second ultrasonic signal reception means (Rx1, Rx2) are adjacently installed. At this time, assuming that a position number of first ultrasonic signal reception means (Rx1) is “1”, and a position number of second ultrasonic signal reception means (Rx2) is “2”, when the first and second ultrasonic signals are received by the first and second ultrasonic signal reception means (Rx1, Rx2), the microcomputer 5 can accurately recognize that the mobile robot is moving in a direction opposite to the charging station through those position numbers since the first and second ultrasonic signal reception means (Rx1, Rx2) are installed at the rear of the outer circumferential surface of the mobile robot. Hereinafter, processes for calculating a distance and an angle between the mobile robot and the charging station will now be described. First, the microcomputer 6 detects reaching time taken for each of first and second ultrasonic signals to be received by one or more ultrasonic signal reception means (Rx1˜Rxn) after being sequentially oscillated by the first and second ultrasonic signal oscillating means 3, 4, on the basis of a point of time at which an RF signal, which is generated at preset time intervals, is generated. Then, the microcomputer 6 calculates a distance between the mobile robot and the charging station based on the detected reaching time. Herein, the first and second ultrasonic signals may be received by one ultrasonic signal reception means (e.g., Rx1) or may be received by two or more ultrasonic signal reception means (e.g., Rx1˜Rx3). For example, the microcomputer 6 detects reaching time taken for each of first and second ultrasonic signals to be received by one or more ultrasonic signal reception means (Rx1˜Rxn) after being oscillated by the first and second ultrasonic signal oscillating means 3, 4, on the basis of a point of time at which an RF signal, which is generated at preset time intervals, is generated. Then, the microcomputer 6 calculates a distance between the mobile robot and the charging station based on the detected reaching time. That is, when first and second ultrasonic signals are detected only in one ultrasonic signal reception means (Rx1), the microcomputer 6 calculates a distance value between the one ultrasonic signal reception means (Rx1) and the charging station based on the reaching time taken for each of first and second ultrasonic signals to be received by the one ultrasonic signal reception means (Rx1), and calculates an actual distance between the mobile robot and the charging station by adding a semidiameter of the mobile robot to the calculated distance value. In addition, an angle between the mobile robot and the charging station is calculated through triangulation based on the reaching time of each of first and second ultrasonic signals and a preset distance value between the first and second ultrasonic signal oscillating means 3, 4. On the other hand, when first and second ultrasonic signals are detected in two ultrasonic signal reception means (e.g., Rx1, Rx2), the microcomputer 6 calculates distances between the mobile robot and the charging station based on reaching time of each of first and second ultrasonic signals. Then, the microcomputer 6 calculates an angle between the mobile robot and the charging station through triangulation based on each obtained distance value and a preset distance value between the first and second ultrasonic signal oscillating means 3, 4. Herein, the microcomputer 6 detects a distance (s) between the ultrasonic signal reception means and the ultrasonic signal oscillating means through expression 1 below. S=340[m/sec]×(T1−T2) expression 1 Herein, 340[m/sec] is the sound velocity, T1 is time taken to receive an ultrasonic signal, and T2 is time taken to oscillate an ultrasonic signal after receiving an RF signal. Hereinafter, operations of an apparatus for detecting a position of a mobile robot in accordance with an embodiment of the present invention will now be described in detail with reference to FIGS. 2, 3. FIG. 2 is a flow chart of a method for detecting a position of a mobile robot in accordance with an embodiment of the present invention. FIG. 3 is a schematic view showing processes for calculating a distance and an angle between a mobile robot and a charging station in accordance with the present invention. First, when predetermined time elapses (S1), the RF generating means 1 generates an RF signal (S2). The RF signal is generated whenever predetermined time elapses. First and second ultrasonic signal oscillating means 3, 4 each installed at the charging station sequentially oscillate first and second ultrasonic signals on the basis of a point of time at which the RF signal is generated (S3). Herein, the first ultrasonic signal is oscillated earlier than the second ultrasonic signal. Accordingly, when detecting actual reaching time of the second ultrasonic signal oscillated when predetermined time elapses after the oscillation of the first ultrasonic signal, the microcomputer 6 detects the actual reaching time of the second ultrasonic signal by subtracting the predetermined time from the reaching time of the second ultrasonic signal including the predetermined time. Thereafter, the microcomputer 6 detects time (reaching time) taken for each of first and second ultrasonic signals to be received by one or more ultrasonic signal reception means, and then calculates a distance and an angle between the mobile robot and the charging station based on the detected reaching time and a preset distance value between the first and second ultrasonic signals oscillating means 3, 4. Herein, the first and second ultrasonic signals may be received by one, or two or more ultrasonic signal reception means according to a position of the mobile robot. Hereinafter, there will be sequentially described processes for detecting a position of a mobile robot when first and second ultrasonic signal are received by one ultrasonic signal reception means (e.g., Rx1) and received by two or more ultrasonic signal reception means (e.g., Rx1˜Rx3). First, the microcomputer 6 determines whether two or more ultrasonic signal reception means receive the first and second ultrasonic signals (S4). For example, when the first and second ultrasonic signal are detected only in one ultrasonic signal reception means (Rx1), the microcomputer 6 calculates a distance value between the one ultrasonic signal reception means (Rx1) and the charging station based on reaching time of the detected first and second ultrasonic signals. For example, the microcomputer 6 calculates reaching time of the first ultrasonic signal (S5) and calculates distances between the ultrasonic reception means (Rx1) and each first and second ultrasonic signal oscillating means 3, 4 (S6). In addition, by adding a semidiameter of the mobile robot to the distance value between the ultrasonic signal reception means (Rx1) and the charging station, the microcomputer 6 calculates an actual distance between the mobile robot and the charging station (S7). Herein, an angle between the mobile robot and the charging station is calculated through a triangulation based on a distance value between the ultrasonic signal reception means (Rx1) and the first ultrasonic signal oscillating means 3 of the charging station, a distance value between the ultrasonic signal reception means (Rx1) and the second ultrasonic signal oscillating means 4, and a preset distance value between the first and second ultrasonic signal oscillating means (S8). When first and second ultrasonic signals are received by two or more ultrasonic signals reception means (e.g., Rx1˜Rx3), the microcomputer 6 calculates reaching time of the first and second ultrasonic signals received by the two or more ultrasonic signal reception means (Rx1˜Rx3) (S9). In order to reduce a calculation amount of the microcomputer 6, the microcomputer 6 selects two ultrasonic signal reception means (e.g., Rx1 and Rx2) which have received ultrasonic signals reaching time of which are the fastest, among the calculated reaching time values (S10), and calculates distance values between the charging station and each of two selected ultrasonic signal reception means based on the reaching time of the first and second ultrasonic signals received by the two selected ultrasonic signal reception means (S11). In addition, by adding a semidiameter of the mobile robot to a distance value between the charging station and each of two selected ultrasonic signal reception means (e.g., Rx1 and Rx2), the microcomputer calculates an actual distance between the mobile robot and the charging station (S12). Thereafter, the microcomputer 6 calculates an angle between the mobile robot (e.g., Rx1 and Rx2) and the charging station through triangulation based on actual distance values between the charging station and the two selected ultrasonic reception means (e.g., Rx1 and Rx2) and a preset distance value between the first and second ultrasonic signal oscillating means 3, 4 (S13). In addition, the microcomputer 6 detects a direction that the mobile robot proceeds through position numbers of two ultrasonic signal reception means which have received the first and second ultrasonic signals, to check a current position of the mobile robot, and compensates a position error of the mobile robot depending on the checked position. Whenever predetermined time elapses (S1), the processes (S2˜S13) for detecting a position of the mobile robot is repeatedly performed. As so far described, an apparatus and a method for detecting a position of a mobile robot in accordance with the present invention can accurately detect a position of a mobile robot by calculating time taken for each ultrasonic signal generated by ultrasonic signal oscillating means of a charging station to reach the mobile robot on the basis of a point of time at which an RF (Radio Frequency) signal emitted from the mobile robot is generated; calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance value between the ultrasonic signal oscillation means. In addition, an apparatus and a method for detecting a position of a mobile robot in accordance with the present invention accurately detect a current position of a mobile robot without using a high-priced CCD camera, to thereby reduce fabrication cost of the mobile robot. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a mobile robot, and particularly, to an apparatus and a method for detecting a position of a mobile robot. 2. Description of the Background Art In general, a mobile robot, particularly, a robot cleaner is a device for automatically cleaning an area to be cleaned by sucking foreign substances such as dust or the like on a floor, while automatically moving along a wall surface of a room (e.g., living room, inner room or the like) of a private home without an operation of a user. The robot cleaner discriminates a distance between itself and an obstacle installed in a cleaning area, such as furniture, office supplies, a wall or the like, through a distance sensor, and selectively drives a motor for driving its left wheel and a motor for driving its right wheel depending on the discriminated distance, so that the robot cleaner automatically switches its direction to clean the cleaning area. Herein, the robot cleaner performs cleaning, moving in the cleaning area through map information stored in an internal storing device. Hereinafter, a mapping operation for generating the map information will now be described. First, the robot cleaner moves along a side surface of an operation space (e.g., wall surface of living room in private home), to calculate a distance and a direction between itself and a charging station installed on a wall, and determines its position based on the calculated distance value and direction value, to scan the operation space. Herein, the robot cleaner detects its current position by using an encoder installed at its wheel. The robot cleaner determines whether there is an obstacle between itself and the charging station. If there is no obstacle, the robot cleaner transmits/receives a signal to/from the charging station to scan an operation space. On the contrary, if there is an obstacle between the robot cleaner and the charging station, the robot cleaner scans another operation space first, and then, when the obstacle is eliminated, it transmits/receives a signal to/from the charging station to scan the operation space where the obstacle has eliminated. However, in the method of detecting a position of the robot cleaner by using the encoder, since the current position of the robot cleaner is searched using the encoder installed at the wheel, an error occurs by sliding of the wheel or an idle rotation. As another method for detecting a position of a robot cleaner in accordance with another conventional art, stickers or reflection plates with the same shapes are attached to an operation space (e.g., wall surface of living room of private home) at prescribed intervals, and the robot cleaner recognizes the sticker or the reflection plate by using a CCD camera to thereby compensate an error occurring by sliding of the wheel or an idle rotation, so that the robot cleaner recognizes a distance between itself and the charging station. However, in this method of detecting a position of the robot cleaner by using the sticker or the reflection plate, when illumination brightness of a cleaning area is changed or a subject having a shape similar to the sticker or the reflection plate is recognized, a distance error may be accumulated. In addition, when illumination brightness is higher or lower than a threshold, a CCD (charge-coupled device) camera cannot recognize the sticker or the reflection plate, and thus the robot cleaner cannot check its position. In addition, since the CCD cameral has to be attached to the robot cleaner, fabrication cost of the robot cleaner is increased. Techniques for a robot cleaner in accordance with conventional arts are also disposed in U.S. Pat. No. 5,440,216 and U.S. Pat. No. 5,646,494. | <SOH> SUMMARY OF THE INVENTION <EOH>Therefore, an object of the present invention is to provide an apparatus and a method for detecting a position of a mobile robot capable of accurately detecting a position of the mobile robot by calculating reaching time taken for each ultrasonic signal to be received by the mobile robot after being oscillated by ultrasonic signal oscillating means of a charging station on the basis of an RF (radio frequency) signal emitted at certain time intervals and a distance value between the ultrasonic signal oscillating means and thus by detecting a position of the mobile robot based on the calculated values. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for detecting a position of a mobile robot comprising: calculating time taken for each ultrasonic signal generated by ultrasonic signal generated means of a charging station to reach the mobile robot on the basis of a point of time at which a RF (Radio Frequency) emitted from the mobile robot is emitted, and calculating a distance between the charging station and the mobile robot based on the calculated reaching time; and calculating an angle between the charging station and the mobile robot based on the calculated distance value and a preset distance value between the ultrasonic signal oscillating means. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for detecting a position of a mobile robot generating an RF (Radio Frequency) signal and ultrasonic signals, calculating reaching time taken for each ultrasonic signal to reach the mobile robot on the basis of a point of time at which the RF signal is generated, and detecting a position of the mobile robot based on the reaching time and a preset distance value between the ultrasonic signal oscillating means for oscillating the ultrasonic signals. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for detecting a position of a mobile robot comprising: an RF generating means installed at a mobile robot and for emitting an RF (Radio Frequency) signal; an RF reception means installed at a charging station and for receiving the RF signal emitted by the RF generating means; ultrasonic signal oscillating means each installed at the charging station and for oscillating ultrasonic signals; a control means for controlling the ultrasonic signal oscillating means so that the ultrasonic signals are oscillated whenever the RF signal is received by the RF reception means; ultrasonic signal reception means installed on an outer circumferential surface of the mobile robot and for receiving the ultrasonic signals oscillated by the ultrasonic signal oscillating means; and a microcomputer installed in the mobile robot and for calculating a distance and an angle between the mobile robot and the charging station based on reaching time taken for each ultrasonic signal to reach the mobile robot and a preset distance value between the ultrasonic signals oscillating means. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. | 20040401 | 20091208 | 20050623 | 78428.0 | 0 | OLSEN, LIN B | APPARATUS AND METHOD FOR DETECTING POSITION OF MOBILE ROBOT | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,229 | ACCEPTED | Icemaker in refrigerator | Icemaker in a refrigerator for making ice automatically is disclosed. The icemaker in includes an ice tray provided to a door on the refrigerator for holding water, an ejector fitted adjacent to the ice tray so as to be rotatable by a motor for ejecting ice from the ice tray, means for detecting a rotation angle of the ejector, and a control part for controlling a rotation direction of the ejector based on information detected at the means. | 1. An icemaker in a refrigerator comprising: an ice tray provided to a door on the refrigerator for holding water; an ejector fitted adjacent to the ice tray so as to be rotatable by a motor for ejecting ice from the ice tray; means for detecting a rotation angle of the ejector; and, a control part for controlling a rotation direction of the ejector based on information detected at the means. 2. The icemaker as claimed in claim 1, further comprising: a dropper having a sloped surface covering a part of an upper part of the ice tray, and an overflow preventing member opposite to the dropper in the upper part of the ice tray. 3. The icemaker as claimed in claim 2, wherein the overflow preventing member is a panel extended upward by a length from the upper part of the ice tray. 4. The icemaker as claimed in claim 3, wherein the panel includes a curved surface facing an inside of the ice tray. 5. The icemaker as claimed in claim 3, wherein the panel is vertical. 6. The icemaker as claimed in claim 1, further comprising a heater for heating the ice tray when the water held in the ice tray is frozen. 7. The icemaker as claimed in claim 1, wherein the means includes; a magnet fitted to a rotating body rotatably interlocked with a shaft of the motor, and at least two sensors fitted to a plate spaced from each other, the plate being arranged opposite to the rotating body, each for sensing a magnetic flux when the magnet comes close thereto, to measure a rotation angle of the ejector. 8. The icemaker as claimed in claim 7, wherein the rotating body is a driven gear rotatably engaged with a driving gear connected to the shaft of the motor, for rotating with the ejector. 9. The icemaker as claimed in claim 7, wherein the sensors include; a first sensor for sensing an initial position of the ejector before the ejector ejects ice, and a second sensor for sensing a finish position when the ejector ejects the ice fully. 10. The icemaker as claimed in claim 9, wherein a distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. 11. The icemaker as claimed in claim 9, wherein the second sensor is fitted in a range of angle of 170°˜280° from the first sensor along a rotation direction of the rotating body. 12. The icemaker as claimed in claim 9, wherein the control part reverses the ejector when the second sensor senses the flux of the magnet. 13. The icemaker as claimed in claim 12, wherein the ejector reverses when the first sensor senses the flux of the magnet. 14. The icemaker as claimed in claim 9, further comprising a heater for heating the ice tray when water held in the ice tray is frozen. 15. The icemaker as claimed in claim 14, wherein the control part turns on the heater when water in the ice tray is frozen, and turns off when the second senor senses the flux of the magnet. 16. The icemaker as claimed in claim 14, wherein the sensors further include a third sensor fitted between the first sensor and the second sensor. 17. The icemaker as claimed in claim 16, wherein a distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. 18. The icemaker as claimed in claim 16, wherein the third sensor is fitted in a range of angle of 35°˜145° from the first sensor along a rotation direction of the rotating body. 19. The icemaker as claimed in claim 16, wherein the control part turns on the heater when water in the ice tray is frozen, and turns off when the third senor senses the flux of the magnet. | This application claims the benefit of the Korean Application No. P2003-66598, filed on Sep. 25, 2003, which is hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to refrigerators, and more particularly, to an icemaker in a refrigerator for making ice automatically. 2. Background of the Related Art The refrigerator is used for long time fresh storage of food. The refrigerator has food storage chambers each of which temperature is maintained in a low temperature state by a refrigerating cycle, for fresh storage of the food. There are a plurality of storage chambers of different characteristics, so that the user can select storage methods suitable for storage of various kinds of food, taking kinds and characteristics of food and required storage time periods into account. Of the storage chambers, the refrigerating chamber and the freezing chamber are typical. The refrigerating chamber is maintained at about 3° C.˜4° C. for long time fresh storage of food and vegetable, and the freezing chamber is maintained at a subzero temperature for long time storage of meat and fish in a frozen state, and making and storage of ice pieces. In the meantime, when it is intended to use ice, it is required to open a door on the refrigerating chamber, and take out the ice from an ice tray. In this case, the user is required to separate the ice from the ice tray, which is very difficult because the ice tray is at a very low temperature. SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an icemaker in a refrigerator that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. An object of the present invention is to provide an icemaker in a refrigerator, which makes ice pieces automatically for user's easy and convenient taking out of ice pieces. Other object of the present invention is to provide an icemaker of improved structure in a refrigerator, which can prevent splash of water from the icemaker when the door is opened or closed. Another object of the present invention is to provide an icemaker of improved structure in a refrigerator, having a structure that can prevent splash of water from an ice tray, in which an ejector that ejects ice pieces from an ice tray is made to be controlled easily by using a simple structure. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the icemaker in a refrigerator includes an ice tray provided to a door on the refrigerator for holding water, an ejector fitted adjacent to the ice tray so as to be rotatable by a motor for ejecting ice from the ice tray, means for detecting a rotation angle of the ejector, and a control part for controlling a rotation direction of the ejector based on information detected at the means. The icemaker further includes a dropper having a sloped surface covering a part of an upper part of the ice tray, and an overflow preventing member opposite to the dropper in the upper part of the ice tray. The overflow preventing member is a panel extended upward by a length from the upper part of the ice tray. The panel includes a curved surface facing an inside of the ice tray, or the panel is vertical. The icemaker further includes a heater for heating the ice tray when the water held in the ice tray is frozen. The means includes a magnet fitted to a rotating body rotatably interlocked with a shaft of the motor, and at least two sensors fitted to a plate spaced from each other, the plate being arranged opposite to the rotating body, each for sensing a magnetic flux when the magnet comes close thereto, to measure a rotation angle of the ejector. The rotating body is a driven gear rotatably engaged with a driving gear connected to the shaft of the motor, for rotating with the ejector. The sensors include a first sensor for sensing an initial position of the ejector before the ejector ejects ice, and a second sensor for sensing a finish position when the ejector ejects the ice fully. A distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. The second sensor is fitted in a range of angle of 170°˜280° from the first sensor along a rotation direction of the rotating body. The control part reverses the ejector when the second sensor senses the flux of the magnet. In this case, it is preferable that the ejector reverses until the first sensor senses the flux of the magnet. The control part turns on the heater when water in the ice tray is frozen, and turns off when the second senor senses the flux of the magnet. The sensors further include a third sensor fitted between the first sensor and the second sensor. In this instance, a distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. The third sensor is fitted in a range of angle of 35°˜145° from the first sensor along a rotation direction of the rotating body. The control part turns on the heater when water in the ice tray is frozen, and turns off when the third senor senses the flux of the magnet. It is to be understood that both the foregoing description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention claimed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings; FIG. 1 illustrates a perspective view showing an icemaker and container in accordance with a first preferred embodiment of the present invention; FIG. 2 illustrates a front view of a driving gear for rotating an ejector, and a driven gear having a magnet fitted thereto in the icemaker in FIG. 1; FIG. 3 illustrates a side view of the driving gear, the driven gear, and a plate having a sensor fitted thereto for sensing a flux of the magnet in FIG. 2; FIG. 4 illustrates a section of the icemaker and the container in FIG. 1, schematically; FIG. 5 illustrates a perspective view an icemaker and a container in accordance with a second preferred embodiment of the present invention; FIG. 6A illustrates a front view of a driving gear for rotating the ejector in FIG. 5, and a driven gear having a magnet fitted thereto; FIG. 6B illustrates a front view of a plate having sensors fitted thereto for sensing flux of the magnet in FIG. 6A; FIG. 7 illustrates a side view of the driving gear, the driven gear, and the plate in FIG. 6A or 6B, schematically; FIGS. 8A to 8C illustrate ejectors at initial positions; wherein FIG. 8A illustrates a section of the icemaker showing a position of the ejector, FIG. 8B illustrates a front view of a driving gear and a driven gear showing a position of a magnet, and FIG. 8C illustrates a front view of a plate showing a position of a first sensor for sensing a flux of the magnet in FIG. 8B; FIGS. 9A to 9C illustrate ejectors at positions at times a heater is turned off; wherein FIG. 9A illustrates a section of the icemaker showing a position of the ejector, FIG. 9B illustrates a front view of a driving gear, and a driven gear showing a position of a magnet, and FIG. 9C illustrates a front view of a plate showing a position of a third sensor for sensing a flux of the magnet in FIG. 9B; and FIGS. 10A to 10C illustrate ejectors at positions when the ejector finishes ejection of ice; wherein FIG. 10A illustrates a section of the icemaker showing a position of the ejector, FIG. 10B illustrates a front view of a driving gear, and a driven gear showing a position of a magnet, and FIG. 10C illustrates a front view of a plate showing a position of a second sensor for sensing a flux of the magnet in FIG. 10B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In describing the embodiments, same parts will be given the same names and reference numerals, and repetitive description of which will be omitted. FIG. 1 illustrates a perspective view showing an icemaker 100 and container 200 in accordance with a first preferred embodiment of the present invention. The icemaker makes a plurality of ice pieces by using cold air in the freezing chamber, and the container 200 holds the ice pieces made at the icemaker 100. Therefore, once the icemaker 100 and the container 200 of the present invention are provided to the refrigerator, the user can use the ice pieces easily. Structures of the icemaker 100 and the container 200 will be described in more detail with reference to the attached drawings. Referring to FIG. 1, the icemaker 100 is provided to, for an example, a freezing chamber of a refrigerator, and includes an ice tray 110, a water supplying part 120, an ejector 140, and a control box 130. The ice tray 110 is semicylindrical with an opened top for storage of water and ice. The ice tray 110 has partition ribs 111 which divide an inside space of the ice tray into many small spaces. As shown in FIG. 1, the partition ribs 111 are projected to a radial direction from an inside surface of the ice tray 110. The partition ribs 111 makes the ice tray 110 to produce a plurality of ice pieces at a time. The water supplying part 120 at one side of the ice tray 110 for supplying water to the ice tray 110. There are brackets 150 in a rear side of the ice tray 110 for fixing the icemaker 100 to the freezing chamber. The ejector 140, arranged adjacent to the ice tray 110, includes a shaft 141, and a plurality of fins 145. The shaft 141, on an axis of the ejector 140, is arranged over an inside of the ice tray 110 to cross a central part along a length direction thereof. The fins 145 extend from an outside circumferential surface of the shaft 141 to a radial direction of the shaft 141. It is preferable that the fins 145 are formed at regular intervals along the length direction of the shaft 141, particularly, one of the fins 145 are arranged to every small space in the ice tray 110 formed by the partition ribs 111. Referring to FIG. 1, the control box 130 is mounted at one outside surface of the ice tray 110. The control box 130 contains a motor (not shown), a driving gear 132, a driven gear 133, and the like, which will be described in more detail, with reference to FIGS. 2 and 3. The driving gear 132 is connected to a shaft 131 of the motor (not shown), and rotated by the motor. The driven gear 133, rotatably engaged with the driving gear 132, has the shaft 141 of the ejector 140 connected thereto. Therefore, when the motor is operated, the driving gear 132 and the driven gear 133, engaged with each other, rotate, to rotate the ejector 140, accordingly. Referring to FIG. 2, it is preferable that the driven gear 133 has more teeth than the driving gear 132, for slow ejection of ice from the ice tray 110 with the ejector 140 even if the shaft 131 of the motor rotates at a fast speed. In the meantime, in the icemaker 100 in accordance with a first preferred embodiment of the present invention, there is a device for detecting a rotation angle of the ejector 140 provided in the control box 130, which will be described with reference to FIGS. 2 and 3. Referring to FIG. 2, there is a magnet 134 fitted to a surface of a rotating body rotatable interlocked with the shaft 131 of the motor, for an example, the driven gear 133. There is a plate 135 arranged opposite to the rotating body, i.e., the driven gear 133 in the control box 130, additionally. The plate 135 has a sensor 136 for sensing a flux of the magnet 134 fitted thereto. The plate 135 is stationary and fixed to the control box 130. Therefore, when the driven gear 133 is rotated to bring the magnet 134 close to the sensor 136, the sensor 136 senses the flux of the magnet 134, such that the control part (not shown) detects a rotation angle of the ejector 140. In the meantime, referring to FIG. 1, there are a plurality of droppers 160 in a front part of the ice tray 110, i.e., in an upper part of a side opposite to a side the brackets 150 are fitted thereto. The droppers 160 extend from the upper part of front part of the ice tray 110 to a part close to the shaft 141. There are small gaps between adjacent droppers 160, through which the fins 145 pass respectively when the shaft 141 rotates. In the meantime, when the shaft 141 rotates, the ice in the ice tray 110 is pushed by the fins 145, separated from the ice tray 110, ejected through the opened top of the ice tray 110, and dropped on the droppers 160. The ice dropped onto the droppers 160 drops under the icemaker 100, and stored in the container 200 under the icemaker 100. According to this, it is required that the upper surfaces of the droppers 160 guide the ice separated from the ice tray 110 to drop downward, well. Therefore, as shown in FIG. 1, in the present invention, it is preferable that the upper surfaces of the droppers 160 are sloped such that parts adjacent to the shaft 141 are positioned higher than the front side of the ice tray 110. It is also required that a structure for preventing the ice pieces separated from the ice tray 110 by the fins 145 drop in a rear side of the ice tray 110. For this, as shown in FIG. 4, it is preferable that a rear side end of the ice tray 110 is positioned slightly higher than the shaft 141, so that the ice pieces, separated from the ice tray 110 as the ice pieces move to a rear side of the ice tray 110 by the fins 145, are guided to the front side of the ice tray 110, and drop on the upper surfaces of the droppers 160, naturally. In the meantime, as shown in FIG. 4, there is a heater 170 on an underside of the ice tray 110. When water supplied to the ice tray 110 is frozen, the heater 170 heats a surface of the ice tray 110 for a short period of time to melt the ice on a surface of the ice tray 110 slightly. Then, the ice pieces in the ice tray 110 are separated easily when the shaft 141 and the fins 145 are rotated. The icemaker 100 of the present invention may be provided with a temperature sensor (not shown), additionally. The temperature senor is fitted to one side of the ice tray 110, for measuring a surface temperature of the ice tray 110. Therefore, the control part (not shown) can determine if the water supplied to the ice tray 110 is frozen with reference to a surface temperature of the ice tray 110 measured with the temperature sensor. However, the icemaker 100 may not be provided with the temperature senor. In this case, the control part rotates the ejector 140 after a preset time period is passed after the supply of the water to the ice tray 110. In the meantime, referring to FIGS. 1 and 4, the container 200 is arranged under the icemaker 100, and has an open top for receiving and storage of the ice pieces dropped from the icemaker 100. Referring to FIGS. 1 and 4, the icemaker 100 of the present invention may be provided with a sensing arm 180 for measuring quantity of ice stored in the container 200, additionally. The sensing arm 180 moves up/down under the control of the control part (not shown) to measure quantity of ice in the container 200. For an example, the sensing arm moves down at regular intervals, when a move down distance of the sensing arm 180 is great if the quantity of ice stored in the container 200 is small, and, opposite to this, a move down distance of the sensing arm 180 is small if the quantity of ice stored in the container 200 is much. Thus, the control part can measures the quantity of ice stored in the container 200 with reference to the move down distance of the sensing arm 180. Thus, once the sensing arm 180 is provided to the icemaker 100, the icemaker 100 can continue or discontinue production of the ice depending on the quantity of the ice stored in the container 200. The operation of the icemaker in the refrigerator in accordance with a first preferred embodiment of the present invention will be described. When power is provided to the icemaker 100, the control part controls the motor to move the ejector 140 to an initial position. The initial position is a position (see FIG. 4) at which the fins 145 of the ejector 140 are set standby before the water supplied to the ice tray 110 is frozen. When the ejector 140 is positioned at the initial position, the sensing arm 180 is operated. If the control part (not shown) determines that there is shortage of ice in the container 200 as a result of operation of the sensing arm 180, water is supplied to the water supplying part 120 of the icemaker 100. The water supplied to the water supplying part 120 is filled in spaces between the partition ribs 111 of the ice tray 110, and frozen by cold air in the freezing chamber. According to this, many pieces of ice each having a fixed size are produced with the partition ribs 111 in the ice tray 110. Once the ice is produced, the control part puts the heater 170 into operation. In this instance, full freeze of the water in the ice tray 110 is determined with reference to a surface temperature of the ice tray 110 the temperature sensor measured, or pass of a preset time period. Upon putting the heater 170 into operation, the ice on the surface of the ice tray 110 melts slightly, and separated from the ice tray 110. Then, as the motor is operated, the shaft 141 and the fins 145 are rotated. Then, the fins 145 push the ice pieces between the partition ribs 111 in a circumferential direction of the ice tray 110, such that the ice pieces, separated from the ice tray fully by the fins 145, are ejected through the open top of the ice tray 110, and drop onto the droppers 160. The ice pieces dropped onto the droppers 160 move along the sloped upper surface of the droppers 160, until the ice pieces drops down to the container 200 under the icemaker 100. In the meantime, the motor keeps running during the ice ejection process. Therefore, the driven gear 133 keeps rotating in a clockwise direction in FIG. 4 together with the ejector 140. When the magnet 134 fitted to the driven gear 133 comes close to the sensor 136 as the driven gear keeps rotating, the sensor 136 senses a flux of the magnet 134. Then, determining that the ice pieces are ejected fully, the control part rotates the ejector 140 only to the initial position, and stops the ejector 140. After the ejector 140 stops at the initial position, the sensing arm 180 senses quantity of the ice in the container 200. If it is determined that there is shortage of ice still with the sensing arm 180, above process is repeated, to keep production of ice pieces, until a certain amount of ice pieces are filled in the container 200 when the control part stops production of the ice with reference to the quantity of ice sensed by the sensing arm 180. In the first embodiment described with reference to FIGS. 1 to 4, the icemaker 100 and the container 200 are provided to the freezing chamber of the refrigerator. Therefore, since the icemaker 100 and the container 200 occupy much of a volume of the freezing chamber, a space of the refrigerator can not be used, effectively. In order to resolve such a problem, an idea may be suggested in which the icemaker 100 and the container 200 are mounted on the door. However, this case causes the following another problem. For production of ice, water is supplied to the ice tray 110 of the icemaker 100. However, when the door is opened in a state water is supplied to the ice tray 110, the water in the ice tray 110 washes heavily within the ice tray 110 by an inertia force, and shaking. According to this, a problem of splash of water from the ice tray 110 is caused when the door is opened and closed. Therefore, the present invention suggests an icemaker of an improved structure which can prevent the splash of the water from the ice tray when the door is opened or closed, which will be described. FIG. 5 illustrates an icemaker 100 and a container 200 in accordance with a second preferred embodiment of the present invention. As shown in FIG. 5, structures of the icemaker 100 and the container 200 are similar to ones described with reference to FIG. 1. Therefore, the second embodiment will be described putting emphasis on characters of the second embodiment distinctive from the first embodiment hereafter. In describing the second embodiment, parts the same with the first embodiment will be given the same names and reference symbols. In order to prevent the splash of water from the icemaker 100, the icemaker 100 in accordance with a second preferred embodiment of the present invention is also provided with a dropper 165 of an improved structure that can prevent the splash of water, and having an overflow preventing member 190. The overflow preventing member 190 and the dropper 165 are provided opposite to each other in an upper part of the ice tray 110 for preventing splash of water from the ice tray 110 when the door on the refrigerator is opened or closed. Referring to FIG. 5, in the second embodiment, the dropper 165 covers a part of an upper part of the ice tray 110. That is, the dropper 165 is not provided with gaps for passing the fins 145 of the ejector 140. Therefore, even if water washes inside of the ice tray 110, the water does not splash over in the dropper side 165. The overflow preventing member 190 is arranged opposite to the dropper 165 in the upper part of the ice tray 110. The overflow preventing member 190 may have a form of a panel extended upward by a length from the upper part of the ice tray. The panel may be curved or flat. When the panel is curved, it is preferable that a surface facing an inside of the ice tray 110 is curved. Then, the water washing inside of the ice tray 110 is guided into the ice tray 110 after moving along the curved surface of the panel. If the panel is flat, it is preferable that the panel stands vertical in the upper part of the ice tray 110. When the overflow panel 190 is vertical, the ice tray 110 and the overflow preventing member 190 can be fabricated as one unit easily by using one mold. The overflow preventing member 190 and the dropper 165 without gap provided to the icemaker 100 in accordance with the second preferred embodiment of the present invention can prevent splash of water to an outside of the icemaker 100. According to this, the icemaker 100 and the container 200 can be mounted on the door of the refrigerator, thereby permitting effective use of the inside space of the refrigerator. In the meantime, once the dropper 165 of above structure is provided, the ejector 140 can not rotate in one direction. Because the fins 145 of the ejector 140 are caught at the dropper 165 when the ejector 140 rotates greater than an angle from the initial position. According to this, the second embodiment of the present invention provides a structure which reverses the ejector 140 once the ejector 140 rotates to a position at which the ice is ejected fully. For this, the icemaker 100 in accordance with the second embodiment of the present invention includes means for detecting a rotation angle of the ejector 140, and a control part for controlling a rotation direction of the ejector with reference to information detected at the means. The means includes a magnet 134, and at least two sensors for sensing a flux of the magnet 134 at positions different from each other, which will be described in detail with reference to the attached drawings. Referring to FIG. 6A, the magnet 134 is fitted to a rotating body rotatably interlocked with a shaft 131 of a motor (not shown). Though the rotating body is fabricated separately and provided in the control box 130, for making the structure simple, and the box 130 compact, it is preferable that the magnet 134 is fitted to the driven gear 133. For reference, the driven gear 133, engaged with the driving gear 132 connected to the shaft 131 of the motor, rotates with the ejector 140. The sensors are fitted to a plate 135, so that the sensors sense a flux when the magnet 134 comes close thereto. As shown in FIG. 6B, the plate 135 is arranged opposite to the rotating body, i.e., the driven gear 133, and the sensor are fitted to the plate 135 spaced from each other. In the second embodiment of the present invention, two or three sensors are provided, which will be described hereafter. At first, an embodiment with two sensors provided to the plate 135 will be described. The first sensor senses the initial position before the ejector 140 ejects ice, and the second sensor 138 senses a finish position at which the ejector 140 ejects ice, fully. It is required that the first sensor 137 and the second sensor 138 sense the flux accurately when the magnet 134 comes close thereto, respectively. For this, it is preferable that a distance from a rotation center of the rotating body, i.e., the driven gear 133 to the magnet 134 is the same with a distance from one point of the plate 135 opposite to the rotation center of the driven gear 133 to the first sensor 137 or the second sensor 138. In the meantime, the second senor 138 is arranged within a range of angle of approx. 170°˜280° from the first sensor 137 depending on a rotation direction of the rotating body, i.e., the driven gear 133. Because the ice pieces is ejected from the ice tray 110 fully when the fins 145 of the ejector 140 rotates to above range of angle. In the icemaker 100 with the two sensors, the control part determines that the ejector 140 ejects the ice fully when the second sensor 138 senses a flux after the ejector 140 is rotated. Therefore, the control part reverses the ejector 140 when the second sensor 138 senses the flux. Of course, the motor of the second embodiment is reversible. When the ejector 140 reverses for the first sensor 137 to sense the flux of the magnet 134, the control part determines that the ejector 140 is at the initial position. According to this, the control part stops the ejector 140 when the first sensor 137 senses the magnetic flux after the ejector 140 reverses. Once above structure is provided, if the ejector 140 ejects the ice fully, the ejector 140 stops at the initial position after the ejector 140 reverses. According to this, the icemaker 100 in accordance with the second embodiment of the present invention can control the ejector 140 easily only by using very simple structure. In the meantime, when the heater 170 is provided to the icemaker 100 in accordance with the second embodiment of the present invention, the control part turns on the heater 170 when water in the ice tray 110 is frozen, and turns off the heater 170 when the second sensor 138 senses the flux of the magnet. When the heater 170 is controlled thus, a heating time period of the heater 170 can be reduced, not only to reduce power consumption, but also to prevent temperature rise of the freezing chamber by the heater 170. Next, a case when three sensors are provided to the icemaker 100 in accordance with the second preferred embodiment of the present invention will be described. In this case, as shown in FIG. 6B, the plate 135 is provided with a third sensor 139 in addition to the first sensor 137 and the second sensor 138. Both the first sensor 137 and the second sensor 138 have the same positions and services with the first embodiment. However, in a case the icemaker 100 is provided with the two sensors, since the heater turns off when the second sensor senses the flux, in a case three sensors are provided, the heater 170 turns off when the third sensor 139 senses the flux. In the meantime, for accurate sensing of the flux of the magnet 134 at the third sensor 139, it is preferable that a distance from a rotation center of the driven gear 133 to the magnet 134 is the same with a distance from one point on the plate 135 opposite to the rotation center of the driven gear 133 to the third sensor 139. Referring to FIG. 6B, the third sensor 139 is arranged between the first sensor 137 and the second sensor 138. In more detail, the third sensor 139 is arranged in a range of angle of approx. 35°˜145° from the first sensor 137, depending on a rotation direction of the rotating body, i.e., the driven gear 133. In the icemaker 100 with the three sensors, when the third sensor 139 senses the flux after the ejector 140 rotates, the control part turns of the heater 170. When the second sensor 138 senses the flux as the ejector 140 keeps rotating, the control part, determining that the ice is ejected fully, reverses the ejector 140. When the first sensor 137 senses the flux after the ejector 140 reverses, the control part, determining that the ejector 140 is at the initial position, stops the ejector 140. When the three sensors are provided to the icemaker 100, the icemaker 100 can turn off the heater 170 earlier than a case when the icemaker 100 has two sensors. The operation of the icemaker 100 in accordance with a second preferred embodiment of the present invention having the foregoing structure will be described. In this instance, a process for producing ice in the icemaker 100, a process for the sensing arm measuring quantity of ice stored in the container 200, and the like are the same with the description given in the first embodiment. Therefore, only a process for the ejector 140 ejecting ice will be described. When power is provided to the icemaker 100, the ejector 140 is set at the initial position. In this instance, since a position the first sensor 137 senses the flux is the initial position, the control part can position the ejector 140 at the initial position, accurately. Positions of the fins 145, the magnet 134, and the sensors 137, 139, and 139 in a state the ejector 140 is at the initial position are shown well in FIGS. 8A˜8C. If water is supplied to the ice tray 110, and the ice is produced in a state the ejector 140 is at the initial position, the control part puts the heater 170 into operation. A surface temperature of the ice tray 110 rises as the heater 170 is operated, to separate the ice from the ice tray 110. Then, the control part puts the motor into operation, to rotate the ejector 140. Then, as the driven gear 133 rotates, a position of the magnet 134 also changes. The ejector 140 rotates until the magnet 134 comes to a position opposite to the third sensor 139. In this instance, positions of the fins 145, the magnet 134, and the sensors 137, 138, and 139 are illustrated in FIGS. 9A˜9C, well. When the third sensor 139 senses the flux, the control part turns off the heater 170. After the heater 170 is turned off, the ejector 140 keeps rotating. Accordingly, after a short time period, the magnet 134 faces the second sensor 138. In this instance, positions of the fins 145, the magnet 134, and the sensors 137, 138, and 139 are illustrated in FIGS. 10A˜10C, well. When the second senor 138 senses the flux, the control part, determining that the ice is ejected fully, reverses the ejector 140. In the meantime, in the case only two sensors 137, and 138 are provided to the icemaker 100, when the second sensor 138 senses the flux, the ejector 140 is rotated, and, at the same time with this, the heater 170 is turned off. If the first sensor 137 senses the flux of the magnet 134 again after the ejector 140 reverses, the control part, determining that the ejector 140 is at the initial position, stops the ejector 140. If there is shortage of ice in the container 200 in a state the ejector 140 is stopped, above process is repeated after water is supplied to the ice tray 110. However, if there is enough ice in the container 200, no water is supplied to the ice tray 110, to stop production of the ice. As has been described, the structure of the present invention has the following advantages. First, the automatic ejection of the many pieces of ice produced at the ice tray permits the user to take out ice pieces from the container any time with convenience and easy without giving an effort of separating the ice from the ice tray. Second, the dropper with the overflow preventing member and without the gaps provided to the ice tray can prevent splash of water in opening or closing of the door on the refrigerator. According to this, the icemaker can be mounted on the door on the refrigerator, and an inside space of the refrigerator can be used, effectively. Third, the ejector and the heater can be operated effectively, even with a simple structure having at least two sensors and one magnet. An operation time period of the heater can be shortened, to reduce an energy consumption. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to refrigerators, and more particularly, to an icemaker in a refrigerator for making ice automatically. 2. Background of the Related Art The refrigerator is used for long time fresh storage of food. The refrigerator has food storage chambers each of which temperature is maintained in a low temperature state by a refrigerating cycle, for fresh storage of the food. There are a plurality of storage chambers of different characteristics, so that the user can select storage methods suitable for storage of various kinds of food, taking kinds and characteristics of food and required storage time periods into account. Of the storage chambers, the refrigerating chamber and the freezing chamber are typical. The refrigerating chamber is maintained at about 3° C.˜4° C. for long time fresh storage of food and vegetable, and the freezing chamber is maintained at a subzero temperature for long time storage of meat and fish in a frozen state, and making and storage of ice pieces. In the meantime, when it is intended to use ice, it is required to open a door on the refrigerating chamber, and take out the ice from an ice tray. In this case, the user is required to separate the ice from the ice tray, which is very difficult because the ice tray is at a very low temperature. | <SOH> SUMMARY OF THE INVENTION <EOH>Accordingly, the present invention is directed to an icemaker in a refrigerator that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. An object of the present invention is to provide an icemaker in a refrigerator, which makes ice pieces automatically for user's easy and convenient taking out of ice pieces. Other object of the present invention is to provide an icemaker of improved structure in a refrigerator, which can prevent splash of water from the icemaker when the door is opened or closed. Another object of the present invention is to provide an icemaker of improved structure in a refrigerator, having a structure that can prevent splash of water from an ice tray, in which an ejector that ejects ice pieces from an ice tray is made to be controlled easily by using a simple structure. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the icemaker in a refrigerator includes an ice tray provided to a door on the refrigerator for holding water, an ejector fitted adjacent to the ice tray so as to be rotatable by a motor for ejecting ice from the ice tray, means for detecting a rotation angle of the ejector, and a control part for controlling a rotation direction of the ejector based on information detected at the means. The icemaker further includes a dropper having a sloped surface covering a part of an upper part of the ice tray, and an overflow preventing member opposite to the dropper in the upper part of the ice tray. The overflow preventing member is a panel extended upward by a length from the upper part of the ice tray. The panel includes a curved surface facing an inside of the ice tray, or the panel is vertical. The icemaker further includes a heater for heating the ice tray when the water held in the ice tray is frozen. The means includes a magnet fitted to a rotating body rotatably interlocked with a shaft of the motor, and at least two sensors fitted to a plate spaced from each other, the plate being arranged opposite to the rotating body, each for sensing a magnetic flux when the magnet comes close thereto, to measure a rotation angle of the ejector. The rotating body is a driven gear rotatably engaged with a driving gear connected to the shaft of the motor, for rotating with the ejector. The sensors include a first sensor for sensing an initial position of the ejector before the ejector ejects ice, and a second sensor for sensing a finish position when the ejector ejects the ice fully. A distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. The second sensor is fitted in a range of angle of 170°˜280° from the first sensor along a rotation direction of the rotating body. The control part reverses the ejector when the second sensor senses the flux of the magnet. In this case, it is preferable that the ejector reverses until the first sensor senses the flux of the magnet. The control part turns on the heater when water in the ice tray is frozen, and turns off when the second senor senses the flux of the magnet. The sensors further include a third sensor fitted between the first sensor and the second sensor. In this instance, a distance from a rotation center of the rotating body to the magnet is the same with a distance from a point of the plate opposite to the rotation center to each of the sensors. The third sensor is fitted in a range of angle of 35°˜145° from the first sensor along a rotation direction of the rotating body. The control part turns on the heater when water in the ice tray is frozen, and turns off when the third senor senses the flux of the magnet. It is to be understood that both the foregoing description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention claimed. | 20040401 | 20060530 | 20050331 | 58292.0 | 0 | TAPOLCAI, WILLIAM E | ICEMAKER IN REFRIGERATOR | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,305 | ACCEPTED | Composition for dyeing human keratin materials, comprising at least one fluorescent dye and at least one associative polymer, process therefor and use thereof | Disclosed herein are compositions comprising at least one fluorescent dye and at least one particular associative polymer, processes using this composition, and a device therefor. Further disclosed herein is the use of a composition comprising at least one fluorescent dye and at least one particular associative polymer for dyeing a human keratin material, such as artificially dyed or pigmented hair and dark skin, with a lightening effect. | 1. A composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium; and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide. 2. The composition according to claim 1, wherein the at least one associative polymer is chosen from those of cationic, nonionic, anionic and amphoteric nature. 3. The composition according to claim 1, wherein the associative polyurethane derivatives are anionic and comprise at least one unit derived from a monomer of the α,β-monoethylenically unsaturated carboxylic acid type. 4. The composition according to claim 1, wherein the associative polyurethane derivatives are cationic and correspond to the formula (Ia): R—X—(P)n-[L-(Y)m]r-L′-(P′)p—X′—R′ (Ia) wherein: R and R′, which may be identical or different, are each chosen from hydrophobic groups and a hydrogen atom; X and X′, which may be identical or different, are each chosen from groups comprising at least one amine functional group optionally bearing at least one hydrophobic group, and groups L″; L, L′ and L″, which may be identical or different, are each chosen from groups derived from a diisocyanate; P and P′, which may be identical or different, are each chosen from groups comprising at least one amine functional group optionally bearing at least one hydrophobic group; Y is chosen from hydrophilic groups; r is an integer ranging from 1 to 100; n, m and p, which may be identical or different, each range from 0 to 1000; provided that the molecule comprises at least one amine functional group chosen from protonated and quaternized amine functional groups and at least one hydrophobic group. 5. The composition according to claim 4, wherein r is an integer ranging from 1 to 50. 6. The composition according to claim 5, wherein r is an integer ranging from 1 to 25. 7. The composition according to claim 1, wherein the associative polyurethane derivatives are chosen from nonionic polyether polyurethanes. 8. The composition according to claim 1, wherein the associative cellulose derivatives are cationic and are chosen from celluloses and hydroxyethylcelluloses quaternized with at least one hydrophobic group. 9. The composition according to claim 1, wherein the associative cellulose derivatives are nonionic and are chosen from hydroxyethylcelluloses modified with at least one hydrophobic group. 10. The composition according to claim 1, wherein the associative polyvinyllactam derivatives are cationic and comprise: a) at least one monomer chosen from monomers of vinyllactam and alkylvinyllactam; b) at least one monomer chosen from monomers of formulae (II) and (III): wherein: X is chosen from an oxygen atom and NR6 radicals, R1 and R6, which may be identical or different, are each chosen from a hydrogen atom and linear and branched C1-C5 alkyl radicals, R2 is chosen from linear and branched C1-C4 alkyl radicals, R3, R4 and R5, which may be identical or different, are each chosen from a hydrogen atom, linear and branched C1-C30 alkyl radicals, and radicals of formula (IV): —(Y2)r—(CH2—CH(R7)—O)x—R8 (IV) Y, Y1 and Y2, which may be identical or different, are each chosen from linear and branched C2-C16 alkylene radicals, R7 is chosen from a hydrogen atom, linear and branched C1-C4 alkyl radicals, and linear and branched C1-C4 hydroxyalkyl radicals, R8 is chosen from a hydrogen atom and linear and branched C1-C30 alkyl radicals, p, q and r, which may be identical or different, are each 0 or 1, m and n, which may be identical or different, are each an integer ranging from 0 to 100, x is an integer ranging from 1 to 100, Z− is an anion chosen from organic and mineral acid anions, with the proviso that: at least one of the substituents chosen from R3, R4, R5 and R8 is chosen from linear and branched C9-C30 alkyl radicals, if m or n is other than zero, then q is equal to 1, and if m or n is equal to zero, then p or q is equal to 0. 11. The composition according to claim 1, wherein the associative polyvinyllactam derivatives are nonionic and are chosen from copolymers of vinylpyrrolidone and of at least one fatty-chain hydrophobic monomer. 12. The composition according to claim 1, wherein the associative unsaturated polyacid derivatives are chosen from anionic polymers comprising at least one hydrophilic unit of olefinic unsaturated carboxylic acid type and at least one hydrophobic unit of unsaturated carboxylic acid (C10-C30) alkyl ester type. 13. The composition according to claim 1, wherein the associative unsaturated polyacid derivatives are chosen from anionic polymers comprising among its monomers at least one α,β-monoethylenically unsaturated carboxylic acid and at least one ester of an α,β-monoethylenically unsaturated carboxylic acid and of an oxyalkylenated fatty alcohol. 14. The composition according to claim 12, wherein the carboxylic acid is chosen from acrylic acids and methacrylic acids. 15. The composition according to claim 13, wherein the carboxylic acid is chosen from acrylic acids and methacrylic acids. 16. The composition according to claim 1, wherein the at least one associative polymer is present in an amount ranging from 0.01% to 10% by weight, relative to the total weight of the composition. 17. The composition according to claim 16, wherein the at least one associative polymer is present in an amount ranging from 0.1% to 5% by weight, relative to the total weight of the composition. 18. The composition according to claim 1, wherein the optionally neutralized fluorescent dye is soluble in the cosmetic medium to at least 0.001 g/l at a temperature ranging from 15° C. to 25° C. 19. The composition according to claim 18, wherein the optionally neutralized fluorescent dye is soluble in the cosmetic medium to at least 0.5 g/l at a temperature ranging from 15° C. to 25° C. 20. The composition according to claim 19, wherein the optionally neutralized fluorescent dye is soluble in the cosmetic medium to at least 1 g/l at a temperature ranging from 15° C. to 25° C. 21. The composition according to claim 20, wherein the optionally neutralized fluorescent dye is soluble in the cosmetic medium to at least 5 g/l at a temperature ranging from 15° C. to 25° C. 22. The composition according to claim 1, wherein the at least one fluorescent dye chosen from dyes in the orange range. 23. The composition according to claim 1, wherein the at least one fluorescent dye provides a reflectance maximum that is in the wavelength range from 500 to 650 nanometers. 24. The composition according to claim 23, wherein the at least one fluorescent dye provides a reflectance maximum that is in the wavelength range from 550 to 620 nanometers. 25. The composition according to claim 1, wherein the at least one fluorescent dye is chosen from the fluorescent dyes belonging to the following families: naphthalimides; cationic and non-cationic coumarins; xanthenodiquinolizines; azaxanthenes; naphtholactams; azlactones; oxazines; thiazines; dioxazines; polycationic fluorescent dyes of azo, azomethine and methine types. 26. The composition according to claim 1, wherein the at least one fluorescent dye is chosen from dyes of the following formulae (F1), (F2), and (F3): wherein: R1 and R2, which may be identical or different, are each chosen from: a hydrogen atom; linear and branched alkyl radicals comprising from 1 to 10 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; aryl and arylalkyl radicals, wherein the aryl group comprises 6 carbon atoms and the alkyl radical comprises from 1 to 4 carbon atoms; the aryl radical is optionally substituted with at least alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; R1 and R2 may optionally be linked so as to form a heterocycle with the nitrogen atom and may comprise at least one other hetero atom, wherein the heterocycle is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals and optionally being interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; and R1 or R2 may optionally be engaged in a heterocycle comprising the nitrogen atom and one of the carbon atoms of the phenyl group bearing the nitrogen atom; R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and alkyl radicals comprising from 1 to 4 carbon atoms; R5, which may be identical or different, are each chosen from a hydrogen atom, halogen atoms and linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally interrupted with at least one hetero atom; R6, which may be identical or different, are each chosen from a hydrogen atom; halogen atoms; linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom and/or optionally substituted with at least one halogen atom; X is chosen from: linear and branched alkyl radicals comprising from 1 to 14 carbon atoms and alkenyl radicals comprising from 2 to 14 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom and/or optionally substituted with at least one halogen atom; 5- and 6-membered heterocyclic radicals optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms, optionally substituted with at least one hetero atom; optionally substituted with at least one aminoalkyl radical chosen from linear and branched aminoalkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted with at least one hetero atom; and optionally substituted with at least one halogen atom; fused and non-fused, aromatic and diaromatic radicals, optionally separated with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 4 carbon atoms, wherein at least one of the aryl radicals is optionally substituted with at least one halogen atom or with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 10 carbon atoms optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom; and a dicarbonyl radical; provided that the group X possibly bears at least one cationic charge; a is equal to 0 or 1; Y−, which may be identical or different, are each an anion chosen from organic and mineral anions; and n is an integer at least equal to 2 and at most equal to the number of cationic charges present in the fluorescent compound. 27. The composition according to claim 26, wherein in the formula (F3) defining R1 and R2, the linear and branched alkyl radicals are chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms. 28. The composition according to claim 26, wherein in the formula (F3) defining R1 and R2, the heterocycle is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms. 29. The composition according to claim 1, wherein the at least one fluorescent dye is present in an amount ranging from 0.01% to 20% by weight, relative to the total weight of the composition. 30. The composition according to claim 29, wherein the at least one fluorescent dye is present in an amount ranging from 0.05% to 10% by weight, relative to the total weight of the composition. 31. The composition according to claim 30, wherein the at least one fluorescent dye is present in an amount ranging from 0.1% to 5% by weight, relative to the total weight of the composition. 32. The composition according to claim 1, further comprising at least one non-fluorescent additional direct dye chosen from direct dyes of nonionic, cationic and anionic nature. 33. The composition according to claim 32, wherein the at least one additional direct dye is chosen from nitrobenzene dyes, azo dyes, anthraquinone dyes, naphthoquinone dyes, benzoquinone dyes, phenothiazine dyes, indigoid dyes, xanthene dyes, phenanthridine dyes, phthalocyanin dyes and triarylmethane-based dyes. 34. The composition according to claim 32, wherein the at least one additional direct dye is present in an amount ranging from 0.0005% to 12% by weight, relative to the total weight of the composition. 35. The composition according to claim 1, wherein the composition is in the form of a lightening dyeing shampoo. 36. The composition according to claim 1, further comprising at least one oxidation base chosen from para-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, ortho-aminophenols and heterocyclic bases, and the acid and base addition salts thereof. 37. The composition according to claim 36, wherein the at least one oxidation base is present in an amount ranging from 0.0005% to 12% by weight, relative to the total weight of the composition. 38. The composition according to claim 36, further comprising at least one coupler chosen from meta-phenylenediamines, meta-aminophenols, meta-diphenols and heterocyclic couplers, and the acid and base addition salts thereof. 39. The composition according to claim 38, wherein the at least one coupler is present in an amount ranging from 0.0001% to 10% by weight, relative to the total weight of the composition. 40. A ready-to-use composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium; at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; and at least one oxidizing agent; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide. 41. The composition according to claim 40, wherein the at least one oxidizing agent is chosen from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts, and enzymes. 42. The composition according to claim 41, wherein the persalts are chosen from perborates and persulphates. 43. The composition according to claim 41, wherein the enzymes are chosen from peroxidases and two-electron and four-electron oxidoreductases. 44. A process for dyeing human keratin fibers with a lightening effect, comprising: a) applying to said keratin fibers a composition for a time that is sufficient to develop desired coloration and lightening, wherein the composition comprises, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium; and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide, b) optionally rinsing the keratin fibers, c) optionally washing the keratin fibers with shampoo and rinsing the keratin fibers, and d) drying the keratin fibers or leaving the keratin fibers to dry. 45. The process according to claim 44, further comprising a preliminary operation comprising separately storing, on the one hand, said composition, and, on the other hand, a composition comprising, in a cosmetically acceptable medium, at least one oxidizing agent, mixing together the two compositions at the time of use, applying this mixture to the keratin fibers for a time that is sufficient to develop desired coloration, rinsing the keratin fibers, and optionally washing the keratin fibers with shampoo, rinsing the keratin fibers again, and drying the keratin fibers. 46. The process according to claim 44, wherein the human keratin fibers are hair with a tone height of less than or equal to 6. 47. The process according to claim 46, wherein the human keratin fibers are hair with a tone height of less than or equal to 4. 48. The process according to claim 44, wherein the human keratin fibers are artificially colored or pigmented. 49. A process for coloring dark skin with a lightening effect, comprising applying to the skin a composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium; and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide; and drying the skin or leaving the skin to dry. 50. A multi-compartment device for coloring and/or lightening keratin fibers, comprising at least one compartment comprising a composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium; and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide, and at least one other compartment comprising a composition comprising at least one oxidizing agent. 51. A method for dyeing a keratin material with a lightening effect comprising, applying to the keratin material a composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in said medium, and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives. 52. The method according to claim 51, wherein the at least one fluorescent dye is chosen from dyes in the orange range. 53. The method according to claim 51, wherein the at least one fluorescent dye provides a reflectance maximum that is in the wavelength range from 500 to 650 nanometers. 54. The method according to claim 53, wherein the at least one fluorescent dye provides a reflectance maximum that is in the wavelength range from 550 to 620 nanometers. 55. The method according to claim 51, wherein the at least one fluorescent dye is chosen from the fluorescent dyes belonging to the following families: naphthalimides; cationic and non-cationic coumarins; xanthenodiquinolizines; azaxanthenes; naphtholactams; azlactones; oxazines; thiazines; dioxazines; monocationic and polycationic fluorescent dyes of azo, azomethine and methine types. 56. The method according to claim 51, wherein the at least one fluorescent dye is chosen from dyes of the following formulae (F1), (F2), (F3), and (F4): wherein: R1 and R2, which may be identical or different, are each chosen from: a hydrogen atom; linear and branched alkyl radicals comprising from 1 to 10 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; aryl and arylalkyl radicals, wherein the aryl group comprises 6 carbon atoms and the alkyl radical comprises from 1 to 4 carbon atoms; the aryl radical is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; R1 and R2 may optionally be linked so as to form a heterocycle with the nitrogen atom and may comprise at least one other hetero atom, wherein the heterocycle is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals and is optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; and R1 or R2 may optionally be engaged in a heterocycle comprising the nitrogen atom and one of the carbon atoms of the phenyl group bearing said nitrogen atom; R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and alkyl radicals comprising from 1 to 4 carbon atoms; R5, which may be identical or different, are each chosen from a hydrogen atom, halogen atoms, and linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally interrupted with at least one hetero atom; R6, which may be identical or different, are each chosen from a hydrogen atom; halogen atoms; linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom and/or optionally substituted with at least one halogen atom; X is chosen from: linear and branched alkyl radicals comprising from 1 to 14 carbon atoms and alkenyl radicals comprising from 2 to 14 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; 5- and 6-membered heterocyclic radicals optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms, optionally substituted with at least one hetero atom; optionally substituted with at least one aminoalkyl radical chosen from linear and branched aminoalkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted with at least one hetero atom; and optionally substituted with at least one halogen atom; fused and non-fused, aromatic and diaromatic radicals, optionally separated with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 4 carbon atoms, wherein at least one of the aryl radicals is optionally substituted with at least one halogen atom or with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 10 carbon atoms optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom; and a dicarbonyl radical; provided that the group X possibly bears at least one cationic charge; a is equal to 0 or 1; Y−, which may be identical or different, are each an anion chosen from organic and mineral anions; n is an integer at least equal to 2 and at most equal to the number of cationic charges present in the fluorescent compound; and wherein R is chosen from methyl and ethyl radicals; R′ are each a methyl radical and X− is an anion. 57. The method according to claim 56, wherein in the formula (F3) defining R1 and R2, the linear and branched alkyl radicals are chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms. 58. The method according to claim 56, wherein in the formula (F3) defining R1 and R2, the heterocycle is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms. 59. The method according to claim 56, wherein in the formula (F4), X− is an anion chosen from chloride, iodide, sulphate, methasulphate, acetate, and perchlorate. 60. The method according to claim 51, wherein the at least one fluorescent dye is present in an amount ranging from 0.01% to 20% by weight, relative to the total weight of the composition. 61. The method according to claim 60, wherein the at least one fluorescent dye is present in an amount ranging from 0.05% to 10% by weight, relative to the total weight of the composition. 62. The method according to claim 61, wherein the at least one fluorescent dye is present in an amount ranging from 0.1% to 5% by weight, relative to the total weight of the composition. 63. The method according to claim 51, wherein the at least one associative polymer is present in an amount ranging from 0.01% to 10% by weight, relative to the total weight of the composition. 64. The method according to claim 63, wherein the at least one associative polymer is present in an amount ranging from 0.1% to 5% by weight, relative to the total weight of the composition. 65. The method according to claim 51, wherein the keratin material is chosen from artificially colored and pigmented keratin fibers and dark skin. 66. The method according to claim 65, wherein the keratin fibers are hair. 67. The method according to claim 66, wherein the hair has a tone height of less than or equal to 6. 68. The method according to claim 67, wherein the hair has a tone height of less than or equal to 4. | This application claims benefit of U.S. Provisional Application No. 60/468,080, filed May 6, 2003. Disclosed herein are compositions comprising at least one fluorescent dye and at least one associative polymer, and the processes and a device for using the composition. Further disclosed herein is the use of the composition comprising at least one fluorescent dye and at least one associative polymer to dye with a lightening effect human keratin materials, for example, keratin fibers such as artificially dyed or pigmented hair, and dark skin. It is common for individuals with dark skin to wish to lighten their skin and for this purpose to use cosmetic or dermatological compositions containing bleaching agents. The substances most commonly used as bleaching agents are hydroquinone and its derivatives, kojic acid and its derivatives, azelaic acid, and arbutin and its derivatives, alone or in combination with other active agents. However, these agents have some drawbacks. For example, they need to be used for a long time and in large amounts in order to obtain a bleaching effect on the skin. No immediate effect is observed upon applying compositions comprising them. In addition, hydroquinone and its derivatives are used in an amount that is effective to produce a visible bleaching effect. For example, hydroquinone is known for its cytotoxicity towards melanocyte. Moreover, kojic acid and its derivatives have the drawback of being expensive and consequently of not being able to be used in large amounts in products for commercial mass distribution. There is thus still a need for cosmetic compositions that allow a lighter, uniform, homogeneous skin tone of natural appearance to be obtained, and at the same time, these compositions can have satisfactory transparency after application to the skin. In the field of haircare, there are mainly two types of hair dyeing. The first type is semi-permanent dyeing or direct dyeing, which uses dyes capable of giving the hair's natural color a more or less pronounced modification that can withstand shampooing several times. These dyes are known as direct dyes and may be used in two different ways. The colorations may be performed by applying a composition comprising at least one direct dye directly to the keratin fibers, or by applying a mixture, prepared extemporaneously, of a composition comprising at least one direct dye with a composition comprising at least one oxidizing bleaching agent, which is, for example, aqueous hydrogen peroxide solution. Such a process is then termed “lightening direct dyeing.” The second type is permanent dyeing or oxidation dyeing. This can be performed with “oxidation” dye precursors, which are colorless or weakly colored compounds which, once mixed with oxidizing products, at the time of use, can give rise to colored compounds and dyes via a process of oxidative condensation. At least one direct dye is often used in combination with the oxidation bases and couplers in order to neutralize or attenuate the shades with too much of a red, orange or golden glint or, on the contrary, to accentuate these red, orange or golden glints. Among the available direct dyes, nitrobenzene direct dyes are not sufficiently strong, and indoamines, quinone dyes and natural dyes may have low affinity for keratin fibers and consequently lead to colorations that may not be sufficiently fast with respect to the various treatments to which the keratin fibers may be subjected, such as shampooing. In addition, there is a need to obtain a lightening effect on human keratin fibers. This lightening has conventionally been obtained via a process of bleaching the melanins of the hair via an oxidizing system generally comprising hydrogen peroxide optionally combined with persalts. This bleaching system may have the drawback of degrading the keratin fibers and of impairing their cosmetic properties. Therefore, there is still a need to solve at least one of the problems mentioned above, and, for example, to provide a composition that can have good dyeing affinity for keratin materials such as keratin fibers, good resistance properties with respect to external agents, such as with respect to shampooing, and that can also make it possible to obtain lightening without impairing the treated material, such as the keratin fibers. It has thus been found, surprisingly and unexpectedly, that the use of fluorescent dyes, such as those in the orange range, in the presence of particular associative polymers, can satisfy at least one of these needs. Disclosed herein is thus a composition comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in the medium and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives; provided that the composition does not comprise, as a fluorescent agent, 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide. Further disclosed herein is a process for dyeing human keratin fibers with a lightening effect, comprising: a) applying to the keratin fibers the composition disclosed herein for a time that is sufficient to develop a desired coloration and lightening, b) optionally rinsing the keratin fibers, c) optionally washing the keratin fibers with shampoo and optionally rinsing the keratin fibers, and d) drying or leaving the keratin fibers to dry. Further disclosed herein is the use of a composition for dyeing human keratin materials with a lightening effect, comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in the medium, and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives. Further disclosed herein is a multi-compartment device for dyeing and lightening keratin fibers, comprising at least one compartment comprising the composition disclosed herein, and at least one other compartment comprising a composition comprising at least one oxidizing agent. The compositions disclosed herein can, for example, allow better fixing of the fluorescent dye onto the keratin materials, which is reflected by an increased fluorescent effect and a lightening effect that is greater than that obtained with the fluorescent dye used alone. Better resistance of the result with respect to washing or shampooing can also be obtained. However, other characteristics and advantages of the present disclosure will emerge more clearly on reading the description and the examples that follow. Unless otherwise indicated, the limits of the ranges of values that are given in the description are included in these ranges. As has been mentioned previously, the composition disclosed herein comprises at least one fluorescent dye and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives. The associative polymers are hydrophilic polymers capable, in an aqueous medium, of reversibly combining together or with other molecules. Their chemical structure, for example, may comprise at least one hydrophilic region and at least one hydrophobic region. The term “hydrophobic group” means a radical or polymer comprising at least one chain chosen from saturated and unsaturated, linear and branched hydrocarbon-based chains. When it denotes a hydrocarbon-based radical, the hydrophobic group comprises at least 10 carbon atoms, such as from 10 to 30 carbon atoms, further such as from 12 to 30 carbon atoms, and even further such as from 18 to 30 carbon atoms. In one embodiment, the hydrocarbon-based group is derived from a monofunctional compound. By way of example, the hydrophobic group may be derived from a fatty alcohol such as stearyl alcohol, dodecyl alcohol and decyl alcohol. It may also be a hydrocarbon-based polymer, for example, polybutadiene. The associative polymers present in the composition disclosed herein may be of nonionic, anionic, cationic or amphoteric nature. Among the associative polyurethane derivatives that may be mentioned are, for example, anionic copolymers obtained by polymerization of: from 20% to 70% by weight of an α,β-monoethylenically unsaturated carboxylic acid, from 20% to 80% by weight of a non-surfactant α,β-monoethylenically unsaturated monomer different from the preceding monomer, and from 0.5% to 60% by weight of a nonionic monourethane, which is the product of reaction of a monohydroxylated surfactant with a monoethylenically unsaturated monoisocyanate. Such derivatives are described, for example, in European document EP 173 109, such as in Example 3. In one embodiment, this polymer is a methacrylic acid/methyl acrylate/ethoxylated (40 EO) behenyl alcohol dimethyl-meta-isopropenylbenzylisocyanate terpolymer as an aqueous 25% dispersion. This product is sold under the reference Viscophobe DB1000 by the company Amerchol. Mention may also be made of the cationic associative polyurethanes whose family has been described, for example, in French patent application FR 00/09609. It may be represented, for example, by the general formula (Ia) below: R—X-(P)n-[L-(Y)m]r-L′-(P′)p—X′—R′ (Ia) wherein: R and R′, which may be identical or different, are each chosen from hydrophobic groups and a hydrogen atom; X and X′, which may be identical or different, are each chosen from groups comprising at least one amine functional group optionally bearing at least one hydrophobic group, and a group L″; L, L′ and L″, which may be identical or different, are each chosen from groups derived from a diisocyanate; P and P′, which may be identical or different, are each chosen from groups comprising at least one amine functional group optionally bearing at least one hydrophobic group; Y is chosen from hydrophilic groups; r is an integer ranging from 1 to 100, such as from 1 to 50, and further such as from 1 to 25; n, m and p, which may be identical or different, each range from 0 to 1000; provided that the molecule comprises at least one amine functional group chosen from protonated and quaternized amine functional groups and at least one hydrophobic group. In one embodiment, the only hydrophobic groups of these polyurethanes are the groups R and R′ located at the chain ends. In another embodiment, the cationic associative polyurethane corresponds to the formula (Ia) described above, wherein: R and R′ are each chosen from hydrophobic groups, X and X′ are each a group L″, n and p range from 1 to 1000, and L, L′, L″, P, P′, Y and m have the meaning given in the above-mentioned formula (Ia). In yet another embodiment, the cationic associative polyurethane corresponds to the formula (Ia) above, wherein: R and R′ are each chosen from hydrophobic groups, X and X′ are each a group L″, n and p are 0, and L, L′, L″, Y and m have the meaning given in the above-mentioned formula (Ia). The fact that n and p are 0 means that these polymers do not comprise units derived from a monomer comprising at least one amine functional group incorporated into the polymer during the polycondensation. The protonated amine functional groups of these polyurethanes result from the hydrolysis of excess isocyanate functional groups, at the chain end, followed by alkylation of the primary amine functional groups formed with alkylating agents comprising at least one hydrophobic group, i.e., compounds of the type RQ or R′Q, wherein R and R′ are as defined above and Q is a leaving group such as a halide, a sulphate, etc. In yet another embodiment, the cationic associative polyurethane corresponds to the formula (Ia) above wherein: R and R′ are each chosen from hydrophobic groups, X and X′ are each a group comprising a quaternary amine functional group, n and p are zero, and L, L′, Y and m have the meaning given in the above-mentioned formula (Ia). The number-average molecular mass of the cationic associative polyurethanes ranges, for example, from 400 to 500 000, such as from 1000 to 400 000, and further such as from 1000 to 300 000 g/mol. When at least one of X and X′ is a group comprising at least one amine functional group chosen from tertiary and quaternary amine functional groups, at least one of X and X′ may be a group of one of the following formulae: wherein: R2 is a radical chosen from linear and branched alkylene radicals comprising from 1 to 20 carbon atoms, optionally comprising at least one ring chosen from saturated and unsaturated rings, and arylene radicals, wherein at least one of the carbon atoms is possibly replaced with a hetero atom chosen from N, S, O and P; R1 and R3, which may be identical or different, are each a radical chosen from linear and branched C1-C30 alkyl and alkenyl radicals, and aryl radicals, wherein at least one of the carbon atoms is possibly replaced with a hetero atom chosen from N, S, O and P; A− is a physiologically acceptable counterion. The groups L, L′ and L″ are each a group of formula: wherein: Z is —O—, —S— or —NH—; and R4 is a radical chosen from linear and branched alkylene radicals comprising from 1 to 20 carbon atoms, optionally comprising at least one ring chosen from saturated and unsaturated rings, and arylene radicals, wherein at least one of the carbon atoms is possibly replaced with a hetero atom chosen from N, S, O and P. The groups P and P′ may comprise at least one amine functional group and may each be a group of at least one of the following formulae: wherein: R5 and R7, which may be identical or different, have the same meanings as R2 defined above; R6, R8 and R9, which may be identical or different, have the same meanings as R1 and R3 defined above; R10 is a group chosen from linear and branched, optionally unsaturated alkylene groups possibly comprising at least one hetero atom chosen from N, O, S and P; and A− is a cosmetically acceptable counterion. With regard to the meaning of Y, the term “hydrophilic group” means a polymeric or non-polymeric water-soluble group. By way of example, when it is not a polymer, mention may be made of ethylene glycol, diethylene glycol and propylene glycol. When it is a hydrophilic polymer, in accordance with one embodiment, mention may be made, for example, of polyethers, sulphonated polyesters, sulphonated polyamides or a mixture of these polymers. The hydrophilic compound is, for example, a polyether, such as a poly(ethylene oxide) and a poly(propylene oxide). The cationic associative polyurethanes of the formula (Ia) disclosed herein may be formed from diisocyanates and from various compounds with functional groups comprising at least one labile hydrogen. The functional groups comprising at least one labile hydrogen may be chosen, for example, from alcohol, primary and secondary amine, and thiol functional groups, giving, after reaction with the diisocyanate functional groups, polyurethanes, polyureas and polythioureas, respectively. As used herein, the term “polyurethanes” includes these three types of polymers, namely polyurethanes, polyureas and polythioureas, and also copolymers thereof. A first type of compound involved in the preparation of the polyurethane of the formula (Ia) is a compound comprising at least one unit comprising at least one amine functional group. This compound may be multifunctional, for example, the compound may be difunctional, i.e., in one embodiment, this compound comprises two labile hydrogen atoms borne, for example, by a hydroxyl, primary amine, secondary amine or thiol functional group. A mixture of multifunctional and difunctional compounds in which the percentage of multifunctional compounds is low may also be used. As mentioned above, this compound may comprise more than one unit comprising at least one amine functional group. In this case, it is a polymer bearing a repetition of the unit comprising at least one amine functional group. Compounds of this type may be represented by the following formula: HZ-(P)n-ZH or HZ-(P′)p-ZH wherein Z, P, P′, n and p are as defined above. Examples of compounds comprising at least one amine functional group that may be mentioned include N-methyldiethanolamine, N-tert-butyldiethanolamine and N-sulphoethyldiethanolamine. A second compound involved in the preparation of the polyurethane of the formula (Ia) may be a diisocyanate corresponding to the formula O═C═N—R4—N═C═O wherein R4 is as defined above. Mention may be made, for example, of methylenediphenyl diisocyanate, methylenecyclohexane diisocyanate, isophorone diisocyanate, toluene diisocyanate, naphthalene diisocyanate, butane diisocyanate and hexane diisocyanate. A third compound that may be involved in the preparation of the polyurethane of the formula (Ia) is a hydrophobic compound intended to form the terminal hydrophobic groups of the polymer of the formula (Ia). This compound comprises at least one hydrophobic group and at least one functional group comprising a labile hydrogen, for example, a hydroxyl, primary or secondary amine, or thiol functional group. By way of example, this compound may be a fatty alcohol such as stearyl alcohol, dodecyl alcohol and decyl alcohol. When this compound comprises a polymeric chain, it may be, for example, α-hydroxylated hydrogenated polybutadiene. The hydrophobic group of the polyurethane of the formula (Ia) may also result from the quaternization reaction of the tertiary amine of the compound comprising at least one tertiary amine unit. Thus, the hydrophobic group is introduced via the quaternizing agent. This quaternizing agent may be a compound of the type RQ or R′Q, wherein R and R′ are as defined above and Q is a leaving group such as a halide or a sulphate, etc. The cationic associative polyurethane may also comprise at least one hydrophilic block. This block may be provided by a fourth type of compound involved in the preparation of the polymer. This compound may be multifunctional. For example, it may be difunctional. It is also possible to have a mixture of multifunctional and difunctional compounds in which the percentage of multifunctional compound is low. The functional groups comprising a labile hydrogen are chosen from alcohol, primary and secondary amine, and thiol functional groups. This compound may be a polymer terminated at the chain ends with one of these functional groups comprising a labile hydrogen. By way of example, when it is not a polymer, mention may be made of ethylene glycol, diethylene glycol and propylene glycol. When it is a hydrophilic polymer, mention may be made, for example, of polyethers, sulphonated polyesters and sulphonated polyamides, or a mixture of these polymers. The hydrophilic compound is, for example, a polyether such as a poly(ethylene oxide) or a poly(propylene oxide). The hydrophilic group termed Y in the formula (Ia) is optional. Specifically, the units comprising a quaternary amine or protonated functional group may suffice to provide the solubility or water-dispersibility required for this type of polymer in an aqueous solution. Although the presence of a hydrophilic group Y is optional, in one embodiment, the cationic associative polyurethanes disclosed herein comprise such a group. The associative polyurethane derivatives disclosed herein may also be nonionic polyether polyurethanes. For example, the polymers may comprise in their chain both hydrophilic blocks usually of polyoxyethylenated nature and hydrophobic blocks that may be chosen from aliphatic sequences alone and cycloaliphatic and aromatic sequences. In one embodiment, these polyurethane polyethers comprise at least two hydrocarbon-based lipophilic chains comprising from 6 to 30 carbon atoms, separated by a hydrophilic block, wherein the hydrocarbon-based chains are possibly pendent chains, or chains at the end of the hydrophilic block. For example, it is possible for at least one pendent chain to be included. In addition, the polymer may comprise at least one hydrocarbon-based chain at one end or at both ends of a hydrophilic block. The polyurethane polyethers may be multiblock, such as in triblock form. Hydrophobic blocks may be at each end of the chain (for example: triblock copolymer with a hydrophilic central block) or distributed both at the ends and in the chain (for example: multiblock copolymer). These same polymers may also be graft polymers or starburst polymers. The nonionic fatty-chain polyurethane polyethers may be triblock copolymers wherein the hydrophilic block is a polyoxyethylenated chain comprising from 50 to 1000 oxyethylene groups. The nonionic polyurethane polyethers comprise a urethane linkage between the hydrophilic blocks, whence arises the name. Also included in the nonionic hydrophobic-chain polyurethane polyethers may be those in which the hydrophilic blocks are linked to the hydrophobic blocks via other chemical bonds. Examples of nonionic hydrophobic-chain polyurethane polyethers that may be used herein include Rheolate 205® comprising a urea functional group, sold by the company Rheox, or Rheolate® 208, 204 or 212, and also Acrysol RM 184®. Mention may also be made of the product Elfacos T210® comprising a C12-C14 alkyl chain, and the product Elfacos T212® comprising a C18 alkyl chain, from Akzo. The product DW 1206B® from Rohm & Haas comprising a C20 alkyl chain and a urethane linkage, sold at a solids content of 20% in water, may also be used. It is also possible to use solutions or dispersions of these polymers, such as in water or in aqueous-alcoholic medium. Examples of such polymers that may be mentioned are Rheolate® 255, Rheolate® 278 and Rheolate® 244 sold by the company Rheox. The products DW 1206F and DW 1206J sold by the company Rohm & Haas may also be used. The polyurethane polyethers that may be used herein may also be chosen from those described in the article by G. Fonnum, J. Bakke and F k. Hansen, in 271 Colloid Polym. Sci 380-389 (1993). In one embodiment, a polyurethane polyether that may be obtained by polycondensation of at least three compounds comprising (i) at least one polyethylene glycol comprising from 150 to 180 mol of ethylene oxide, (ii) stearyl alcohol or decyl alcohol, and (iii) at least one diisocyanate may also be used. Such polyurethane polyethers are sold, for example, by the company Rohm & Haas under the names Aculyn 46® and Aculyn 44®. Aculyn 46® is a polycondensate of polyethylene glycol comprising 150 or 180 mol of ethylene oxide, of stearyl alcohol and of methylenebis(4-cyclohexyl isocyanate) (SMDI), at 15% by weight in a matrix of maltodextrin (4%) and water (81%); Aculyn 44® is a polycondensate of polyethylene glycol comprising 150 or 180 mol of ethylene oxide, of decyl alcohol and of methylenebis(4-cyclohexyl-isocyanate) (SMDI), at 35% by weight in a mixture of propylene glycol (39%) and water (26%). Among the polymers derived from associative celluloses that may be used herein, mention may be made, for example, of: quaternized cationic celluloses modified with groups comprising at least one hydrophobic chain chosen, for example, from alkyl, arylalkyl and alkylaryl groups comprising at least 8 carbon atoms, or mixtures thereof, quaternized cationic hydroxyethylcelluloses modified with groups comprising at least one hydrophobic chain chosen, for example, from alkyl, arylalkyl and alkylaryl groups comprising at least 8 carbon atoms, or mixtures thereof. The alkyl radicals borne by the above quaternized celluloses or hydroxyethylcelluloses comprise, for example, from 8 to 30 carbon atoms. The aryl radicals are, for example, chosen from phenyl, benzyl, naphthyl and anthryl groups. As examples of quaternized alkylhydroxyethylcelluloses comprising a C8-C30 hydrophobic chain, mention may be made of the products Quatrisoft LM 200®, Quatrisoft LM-X 529-18-A®, Quatrisoft LM-X 529-18B® (C12 alkyl) and Quatrisoft LM-X 529-8® (C18 alkyl) sold by the company Amerchol, and the products Crodacel QM®, Crodacel QL® (C12 alkyl) and Crodacel QS® (C18 alkyl) sold by the company Croda, nonionic cellulose derivatives such as hydroxyethylcelluloses modified with groups comprising at least one hydrophobic chain chosen, for example, from alkyl, arylalkyl and alkylaryl groups, or mixtures thereof, wherein the alkyl groups are chosen, for example, from C8-C22 alkyl groups, for instance the product Natrosol Plus Grade 330 CS® (C16 alkyl) sold by the company Aqualon, and the product Bermocoll EHM 100® sold by the company Berol Nobel, and cellulose derivatives modified with polyalkylene glycol ether alkyl phenol groups, such as the product Amercell Polymer HM-1500® sold by the company Amerchol. With regard to the associative polyvinyllactams that may be used herein, they may be chosen, for example, from those described in the document FR 0 101 106. The polymers are, for example, chosen from cationic polymers and may comprise: a) at least one monomer chosen from monomers of vinyllactam and alkylvinyllactam types; b) at least one monomer chosen from monomers of formulae (II) and (III) below: wherein: X is chosen from an oxygen atom and a radical NR6, R1 and R6, which may be identical or different, are each chosen from a hydrogen atom and linear and branched C1-C5 alkyl radicals, R2 is chosen from linear and branched C1-C4 alkyl radicals, R3, R4 and R5, which may be identical or different, are each chosen from a hydrogen atom, linear and branched C1-C30 alkyl radicals and radicals of formula (IV): —(Y2)r-(CH2—CH(R7)—O)x—R8 (IV) Y, Y1 and Y2, which may be identical or different, are each chosen from linear and branched C2-C16 alkylene radicals, R7is chosen from a hydrogen atom, linear and branched C1-C4 alkyl radicals, and linear and branched C1-C4 hydroxyalkyl radicals, R8 is chosen from a hydrogen atom and linear and branched C1-C30 alkyl radicals, p, q and r, which may be identical or different, are each 0 or 1, m and n, which may be identical or different, are each an integer ranging from 0 to 100, x is an integer ranging from 1 to 100, Z− is an anion chosen from organic and mineral acid anions, with the proviso that: at least one of the substituents R3, R4, R5 and R8 is chosen from linear and branched C9-C30 alkyl radicals, if m or n is other than zero, then q is equal to 1, and if m or n is equal to zero, then p or q is equal to 0. The poly(vinyllactam) polymers disclosed herein may be crosslinked or non-crosslinked and may also be block polymers. In one embodiment, the counterion Z− of the monomers of the formula (II) is chosen from halide ions, phosphate ions, the methosulphate ion and the tosylate ion. In another embodiment, R3, R4 and R5, which may be identical or different, are each chosen from a hydrogen atom and linear and branched C1-C30 alkyl radicals. In yet another embodiment, the monomer b) is a monomer of the formula (II) wherein, for example, m and n are equal to zero. The vinyllactam or alkylvinyllactam monomer is, for example, a compound of formula (V): wherein: s is an integer ranging from 3 to 6, R9 is chosen from a hydrogen atom and C1-C5 alkyl radicals, R10 is chosen from a hydrogen atom and C1-C5 alkyl radicals, with the proviso that at least one of the radicals R9 and R10 is a hydrogen atom. In one embodiment, the monomer of the formula (V) is vinylpyrrolidone. The poly(vinyllactam) polymers disclosed herein may also comprise at least one additional monomer, which is, for example, cationic or nonionic. As polymers that may be used herein, mention may be made, for example, of the following terpolymers comprising: (a) at least one monomer of the formula (V), (b) at least one monomer of the formula (II) wherein p=1, q=0, R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and C1-C5 alkyl radicals, and R5 is chosen from C9-C24 alkyl radicals, and (c) at least one monomer of the formula (III) wherein R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and C1-C5 alkyl radicals. In one embodiment, the terpolymers comprising, on a weight basis, from 40% to 95% of the monomer (a), from 0.1% to 55% of the monomer (c) and from 0.25% to 50% of the monomer (b) are used. Such polymers are described, for example, in patent application WO 00/68282. Poly(vinyllactam) polymers disclosed herein that may be used include, for example, vinylpyrrolidone/dimethylaminopropylmethacrylamide/dodecyldimethylmethacrylamidopropylammonium tosylate terpolymers, vinylpyrrolidone/dimethylaminopropylmethacrylamide/cocoyldimethylmethacrylamidopropyl-ammonium tosylate terpolymers, vinylpyrrolidone/dimethylaminopropylmethacrylamide/lauryldimethylmethacrylamidopropylammonium tosylate or chloride terpolymers. The vinylpyrrolidone/dimethylamino-propylmethacrylamide/lauryldimethylmethacrylamidopropylammonium chloride terpolymer is sold at a concentration of 20% in water by the company ISP under the name Styleze W20. The associative polyvinyllactam derivatives disclosed herein may also be nonionic copolymers of vinylpyrrolidone and of hydrophobic monomers comprising at least one hydrophobic chain, examples of which that may be mentioned include: the products Antaron V216® or Ganex V216® (vinylpyrrolidone/hexadecene copolymer) sold by the company ISP, and the products Antaron V220® or Ganex V220® (vinylpyrrolidone/eicosene copolymer) sold by the company ISP. Among the associative unsaturated polyacid derivatives that may be mentioned are those comprising at least one hydrophilic unit of olefinic unsaturated carboxylic acid type, and at least one hydrophobic unit of unsaturated carboxylic acid (C10-C30) alkyl ester type. These polymers are chosen, for example, from those in which the hydrophilic unit of olefinic unsaturated carboxylic acid type corresponds to the monomer of formula (VI) below: wherein R1 is H, CH3 or C2H5, (i.e., acrylic acid, methacrylic acid or ethacrylic acid units), and wherein the hydrophobic unit of unsaturated carboxylic acid (C10-C30) alkyl ester type corresponds to the monomer of formula (VII) below: wherein R2 is H, CH3 or C2H5 (i.e., acrylate, methacrylate or ethacrylate units); in one embodiment, R2 is H (acrylate units); in another embodiment, R2 is CH3 (methacrylate units); and R3 is chosen from C10-C30 alkyl radicals, such as C12-C22 alkyl radicals. Unsaturated carboxylic acid (C10-C30) alkyl esters comprise, for example, lauryl acrylate, stearyl acrylate, decyl acrylate, isodecyl acrylate, and dodecyl acrylate, and the corresponding methacrylates, lauryl methacrylate, stearyl methacrylate, decyl methacrylate, isodecyl methacrylate and dodecyl methacrylate. Anionic polymers of this type are described and prepared, for example, according to U.S. Pat. Nos. 3,915,921 and 4,509,949. In anionic associative polymers of this type, polymers that are used are, for example, those formed from a mixture of monomers comprising: (i) essentially acrylic acid, (ii) an ester of the formula (VII) described above wherein R2 is H or CH3, and R3 is an alkyl radical chosen from alkyl radicals comprising from 12 to 22 carbon atoms, and (iii) a crosslinking agent, which is a well-known copolymerizable polyethylenic unsaturated monomer, for instance diallyl phthalate, allyl (meth)acrylate, divinylbenzene, (poly)ethylene glycol dimethacrylate and methylenebisacrylamide. Among the anionic associative polymers of this type are, for example, those comprising from 95% to 60% by weight of acrylic acid (hydrophilic unit), from 4% to 40% by weight of C10-C30 alkyl acrylate (hydrophobic unit) and from 0 to 6% by weight of crosslinking polymerizable monomer, and those comprising from 98% to 96% by weight of acrylic acid (hydrophilic unit), from 1% to 4% by weight of C10-C30 alkyl acrylate (hydrophobic unit) and from 0.1% to 0.6% by weight of crosslinking polymerizable monomer, such as those described above. Among the above polymers, the products sold by the company Goodrich under the trade names Pemulen TR1®, Pemulen TR2® and Carbbpol 1382®, and the product sold by the company SEPPIC under the name Coatex SX® may, for example, be used. In one embodiment, Pemulen TR1® is used. Among the associative unsaturated polyacid derivatives that may also be mentioned are, for example, those comprising among their monomers an α,β-monoethylenically unsaturated carboxylic acid and an ester of an α,β-monoethylenically unsaturated carboxylic acid and of an oxyalkylenated fatty alcohol. In one embodiment, these polymers also comprise as monomer at least one ester of an α,β-monoethylenically unsaturated carboxylic acid and of a C1-C4 alcohol. Examples of polymers of this type that may be mentioned include Aculyn 22® sold by the company Rohm & Haas, which is a methacrylic acid/ethyl acrylate/stearyl methacrylate oxyalkylenated terpolymer. The concentration of the at least one associative polymer in the composition disclosed herein may range, for example, from 0.01% to 10% by weight such as from 0.1% to 5% by weight, relative to the total weight of the composition. In the case where the composition is ready-to-use, i.e., when it also comprises at least one oxidizing agent, the concentration of the at least one associative polymer present in the ready-to-use composition may range, for example, from 0.0025% to 10% by weight, such as from 0.025% to 10% by weight, relative to the total weight of the ready-to-use composition. The composition disclosed herein also comprises, as an essential constituent component, at least one fluorescent dye. As used herein, the term “fluorescent dye” means a dye which is a molecule that colors by itself, and thus absorbs light in the visible spectrum and possibly in the ultraviolet spectrum (wavelengths ranging from 360 to 760 nanometers), but which, in contrast with a standard dye, converts the absorbed energy into fluorescent light of a longer wavelength emitted in the visible region of the spectrum. A fluorescent dye as disclosed herein is to be differentiated from an optical brightener. Optical brighteners, which are also known as brighteners, fluorescent brighteners, fluorescent brightening agents, fluorescent whitening agents, whiteners or fluorescent whiteners, are colorless transparent compounds, which do not dye because they do not absorb light in the visible region, but only in the ultraviolet region (wavelengths ranging from 200 to 400 nanometers), and convert the absorbed energy into fluorescent light of a longer wavelength emitted in the visible region of the spectrum; the color impression is then generated solely by purely fluorescent light that is predominantly blue (wavelengths ranging from 400 to 500 nanometers). Finally, the fluorescent dye as disclosed herein is soluble in the medium of the composition. It should be pointed out that the fluorescent dye differs therein from a fluorescent pigment, which itself is insoluble in the medium of the composition. In one embodiment, the fluorescent dye used herein, which is optionally neutralized, is soluble in the medium of the composition to at least 0.001 g/l, such as at least 0.5 g/l, further such as at least 1 g/l and, even further such as at least 5 g/l at a temperature ranging from 15 to 25° C. Moreover, as disclosed herein, the composition does not comprise, as fluorescent dye, a 2-[2-(4-dialkylamino)phenylethenyl]-1-alkylpyridinium wherein the alkyl radical of the pyridinium nucleus is a methyl or ethyl radical, the alkyl radical of the benzene nucleus is a methyl radical, and the counterion is a halide. In one embodiment, the composition does not comprise, as fluorescent dye, a compound chosen from azo, azomethine and methine monocationic heterocyclic fluorescent dyes. The fluorescent dyes disclosed herein are, for example, dyes in the orange range. In one embodiment, the fluorescent dyes disclosed herein lead to a reflectance maximum that is in the wavelength range from 500 to 650 nanometers such as in the wavelength range from 550 to 620 nanometers. Some of the fluorescent dyes disclosed herein are compounds that are known per se. As examples of fluorescent dyes that may be used, mention may be made, for example, of the fluorescent dyes belonging to the following families: naphthalimides; cationic and non-cationic coumarins; xanthenodiquinolizines (such as sulphorhodamines); azaxanthenes; naphtholactams; azlactones; oxazines; thiazines; dioxazines; polycationic fluorescent dyes of azo, azomethine and methine types, alone or as mixtures. For example, the fluorescent dyes of the following families can be used: naphthalimides; cationic and non-cationic coumarins; azaxanthenes; naphtholactams; azlactones; oxazines; thiazines; dioxazines; polycationic fluorescent dyes of azo, azomethine and methine types, alone or as mixtures. Further, for example, the following may be mentioned among the fluorescent dyes: Brilliant Yellow B6GL sold by the company Sandoz and having the following formula (F1): Basic Yellow 2, or Auramine O, sold by the companies Prolabo, Aldrich or Carlo Erba and having the following formula (F2): 4,4′-(imidocarbonyl)bis(N,N-dimethylaniline) monohydrochloride—CAS number 2465-27-2. Mention may also be made of the compounds having the following formula (F3): wherein: R1 and R2, which may be identical or different, are each chosen from: a hydrogen atom; linear and branched alkyl radicals comprising from 1 to 10 carbon atoms such as from 1 to 4 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; aryl and arylalkyl radicals, wherein the aryl group comprises 6 carbon atoms and the alkyl radical comprises from 1 to 4 carbon atoms; the aryl radical is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; R1 and R2 may optionally be linked so as to form a heterocycle with the nitrogen atom and may comprise at least one other hetero atom, wherein the heterocycle is optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals, such as those comprising from 1 to 4 carbon atoms, and is optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; and R1 or R2 may optionally be engaged in a heterocycle comprising the nitrogen atom and one of the carbon atoms of the phenyl group bearing the nitrogen atom; R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and alkyl radicals comprising from 1 to 4 carbon atoms; R5, which may be identical or different, are each chosen from a hydrogen atom, halogen atoms, and linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally interrupted with at least one hetero atom; R6, which may be identical or different, are each chosen from a hydrogen atom; halogen atoms; and linear and branched alkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom and/or optionally substituted with at least one halogen atom; X is chosen from: linear and branched alkyl radicals comprising from 1 to 14 carbon atoms and alkenyl radicals comprising from 2 to 14 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms and groups comprising at least one hetero atom and/or optionally substituted with at least one halogen atom; 5- and 6-membered heterocyclic radicals optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms, optionally substituted with at least one hetero atom; optionally substituted with at least one aminoalkyl radical chosen from linear and branched aminoalkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted with at least one hetero atom; and optionally substituted with at least one halogen atom; fused and non-fused, aromatic and diaromatic radicals, optionally separated with at least one alkyl radical comprising from 1 to 4 carbon atoms, wherein at least one of the aryl radicals is optionally substituted with at least one halogen atom or with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 10 carbon atoms optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom; and a dicarbonyl radical; provided that the group X possibly bears at least one cationic charge; a is equal to 0 or 1; Y−, which may be identical or different, are each an anion chosen from organic and mineral anions; and n is an integer at least equal to 2 and at most equal to the number of cationic charges present in the fluorescent compound. As used herein, the term “hetero atom” is an oxygen or nitrogen atom. Among the groups bearing such hetero atoms that may be mentioned, inter alia, are hydroxyl, alkoxy, carbonyl, amino, ammonium, amido (—N—CO—) and carboxyl (—O—CO— or —CO—O—) groups. With regard to the alkenyl groups, they comprise at least one unsaturated carbon-carbon bond (—C═C—). In one embodiment, they comprise only one carbon-carbon double bond. In the formula (F3), the radicals R1 and R2, which may be identical or different, are chosen, for example, from: a hydrogen atom; alkyl radicals comprising from 1 to 10 carbon atoms, such as from 1 to 6 carbon atoms, and further such as from 1 to 4 carbon atoms, optionally interrupted with at least one oxygen atom or optionally substituted with at least one entity chosen from hydroxyl, amino and ammonium radicals and chlorine and fluorine atoms; benzyl and phenyl radicals optionally substituted with at least one radical chosen from alkyl and alkoxy radicals comprising from 1 to 4 carbon atoms such as from 1 to 2 carbon atoms; and with the nitrogen atom, heterocyclic radicals of the pyrrolo, pyrrolidino, imidazolino, imidazolo, imidazolium, pyrazolino, piperazino, morpholino, morpholo, pyrazolo and triazolo types, optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 4 carbon atoms optionally interrupted and/or substituted with at least one entity chosen from nitrogen and oxygen atoms and groups bearing at least one atom chosen from nitrogen and oxygen atoms. With regard to the abovementioned amino or ammonium radicals, the radicals borne by the nitrogen atom may be identical or different and may, for example, be chosen from a hydrogen atom, C1-C10 alkyl radicals, such as C1-C4 alkyl radicals and arylalkyl radicals, wherein, for example, the aryl radical comprises 6 carbon atoms and the alkyl radical comprises from 1 to 10 carbon atoms, such as from 1 to 4 carbon atoms. In one embodiment, the radicals R1 and R2, which may be identical or different, are each chosen from a hydrogen atom; linear and branched C1-C6 alkyl radicals; C2-C6 alkyl radicals substituted with at least one hydroxyl radical; C2-C6 alkyl radicals bearing at least one group chosen from amino and ammonium groups; C2-C6 chloroalkyl radicals; C2-C6 alkyl radicals interrupted with at least one entity chosen from an oxygen atom and groups bearing at least one oxygen atom (for example, ester); aromatic radicals, for example, phenyl, benzyl and 4-methylphenyl radicals; heterocyclic radicals such as pyrrolo, pyrrolidino, imidazolo, imidazolino, imidazolium, piperazino, morpholo, morpholino, pyrazolo and triazolo radicals, optionally substituted with at least one radical chosen from C1-C6 alkyl and aromatic radicals. In another embodiment, the radicals R1 and R2, which may be identical or different, are each chosen from a hydrogen atom, linear and branched C1-C6 alkyl radicals such as methyl, ethyl, n-butyl and n-propyl radicals; 2-hydroxyethyl radicals; alkyltrimethylammonium and alkyltriethylammonium radicals, wherein the alkyl radical is chosen from linear C2-C6 alkyl radicals; (di)alkylmethylamino and (di)alkylethylamino radicals, wherein the alkyl radical is chosen from linear C1-C6 alkyl radicals; —CH2CH2Cl; —(CH2)nOCH3 and —(CH2)n-OCH2CH3 wherein n is an integer ranging from 2 to 6; —CH2CH2—OCOCH3; and —CH2CH2COOCH3. In yet another embodiment, the radicals R1 and R2, which may be identical or different, (for example, which are identical), are each chosen from a methyl radical and an ethyl radical. The radicals R1 and R2, which may be identical or different, may also be chosen from heterocyclic radicals of the pyrrolidino, 3-aminopyrrolidino, 3-(dimethyl)-aminopyrrolidino, 3-(trimethyl)aminopyrrolidino, 2,5-dimethylpyrrolo, 1H-imidazolo, 4-methylpiperazino, 4-benzylpiperazino, morpholo, 3,5-(tert-butyl)-1H-pyrazolo, 1H-pyrazolo and 1H-1,2,4-triazolo types. The radicals R1 and R2, which may be identical or different, may also be chosen and be linked so as to form a heterocycle chosen from heterocycles of formulae (I) and (II) below: wherein R′ is chosen from a hydrogen atom, C1-C3 alkyl radicals, —CH2CH2OH, and —CH2CH2OCH3. In one embodiment, R5, which may be identical or different, are each chosen from a hydrogen atom, fluorine and chlorine atoms, and linear and branched alkyl radicals comprising from 1 to 4 carbon atoms optionally interrupted with at least one atom chosen from oxygen and nitrogen atoms. The substituent R5, if it is other than hydrogen, is, for example, in at least one position chosen from positions 3 and 5 relative to the carbon of the ring bearing the nitrogen substituted with the radicals R1 and R2. In one embodiment, the substituent R5 is in position 3 relative to that carbon. For example, the radicals R5, which may be identical or different, are each chosen from a hydrogen atom; linear and branched C1-C4 alkyl radicals; —O—R51 radicals wherein R51 is chosen from linear C1-C4 alkyl radicals; —R52—O—CH3 radicals wherein R52 is chosen from linear C2-C3 alkyl radicals; —R53—N(R54)2 radicals wherein R53 is chosen from linear C2-C3 alkyl radicals and R54, which may be identical or different, are chosen from a hydrogen atom and a methyl radical. Further, for example, R5, which may be identical or different, is chosen from hydrogen, methyl and methoxy radicals. In one embodiment, R5 is a hydrogen atom. In another embodiment, the radicals R6, which may be identical or different, are each chosen from a hydrogen atom; linear and branched C1-C4 alkyl radicals; —X′ radicals, wherein X′ is chosen from chlorine, bromine and fluorine atoms; —R61—O—R62 radicals wherein R61 is chosen from linear C2-C3 alkyl radicals and R62 is a methyl radical; —R63—N(R64)2 radicals wherein R63 is chosen from linear C2-C3 alkyl radicals and R64, which may be identical or different, are each chosen from a hydrogen atom and a methyl radical; —N(R65)2 radicals wherein R65, which may be identical or different, are each chosen from a hydrogen atom and linear C2-C3 alkyl radicals; —NHCO R66 radicals wherein R66 is chosen from C1-C2 alkyl radicals, C1-C2 chloroalkyl radicals, radicals —R67—NH2, —R67—NH(CH3), —R67—N(CH3)2, —R67—N+(CH3)3, and —R67—N+(CH2CH3)3 wherein R67 is chosen from C1-C2 alkyl radicals. The substituent R6, if it is other than hydrogen, is, for example, in at least one position chosen from positions 2 and 4 relative to the nitrogen atom of the pyridinium ring. In one embodiment, the substituent R6 is in position 4 relative to that nitrogen atom. For example, these radicals R6, which may be identical or different, are each chosen from a hydrogen atom and methyl and ethyl radicals. In one embodiment, R6 is a hydrogen atom. Radicals R3 and R4, which may be identical or different, are each, for example, chosen from a hydrogen atom and alkyl radicals comprising from 1 to 4 carbon atoms. In one embodiment, radicals R3 and R4 are each a methyl radical. In another embodiment, radicals R3 and R4 are each a hydrogen atom. As mentioned above, X is chosen, for example, from: linear and branched alkyl radicals comprising from 1 to 14 carbon atoms and alkenyl radicals comprising from 2 to 14 carbon atoms, optionally interrupted and/or substituted with at least one entity chosen from hetero atoms, and groups bearing at least one hetero atom, and optionally substituted with at least one halogen atom; 5- and 6-membered heterocyclic radicals optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms; optionally substituted with at least one aminoalkyl radical chosen from linear and branched aminoalkyl radicals comprising from 1 to 4 carbon atoms, optionally substituted with at least one hetero atom; and optionally substituted with at least one halogen atom; fused and non-fused, aromatic and diaromatic radicals, optionally separated with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 4 carbon atoms, wherein at least one of the aryl radicals is optionally substituted with at least one halogen atom or with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 10 carbon atoms optionally substituted and/or interrupted with at least one entity chosen from hetero atoms and groups bearing at least one hetero atom; and a dicarbonyl radical. In addition, the group X may bear at least one cationic charge. Thus, X may be chosen, for example, from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms and alkenyl radicals comprising from 2 to 14 carbon atoms, may be substituted and/or interrupted with at least one entity chosen from oxygen and nitrogen atoms and groups bearing at least one hetero atom, and may be substituted with at least one atom chosen from fluorine and chlorine atoms. Among the groups of this type that may be mentioned, for example, are hydroxyl, alkoxy (such as with a radical R of the C1-C4 alkyl type), amino, ammonium, amido, carbonyl and carboxyl groups (—COO— or —O—CO—) such as with a radical of alkyloxy type. The nitrogen atom, if present, may be in a quaternized or non-quaternized form. In this case, the other radical or the other two radicals borne by the quaternized or non-quaternized nitrogen atom can be identical or different and may be chosen from a hydrogen atom and C1-C4 alkyl radicals, such as a methyl radical. In one embodiment, the group X is chosen from 5- and 6-membered heterocyclic radicals of the imidazolo, pyrazolo, triazino and pyridino types, optionally substituted with at least one alkyl radical chosen from linear and branched alkyl radicals comprising from 1 to 14 carbon atoms, such as from 1 to 10 carbon atoms, and further such as from 1 to 4 carbon atoms; optionally substituted with at least one aminoalkyl radical chosen from linear and branched aminoalkyl radicals comprising from 1 to 10 carbon atoms, and such as from 1 to 4 carbon atoms, optionally substituted with at least one group comprising at least one hetero atom (such as a hydroxyl radical); and optionally substituted with at least one halogen atom. For example, the amino group can be linked to the heterocycle. In another embodiment, the group X is chosen from aromatic radicals comprising, for example, 6 carbon atoms, fused and non-fused diaromatic radicals comprising, for example, from 10 to 12 carbon atoms, possibly separated with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 4 carbon atoms, wherein at least one of the aryl radicals is optionally substituted with at least one entity chosen from halogen atoms and alkyl radicals comprising from 1 to 10 carbon atoms, such as from 1 to 4 carbon atoms, optionally interrupted with at least one entity chosen from oxygen and nitrogen atoms and groups comprising at least one hetero atom, for example, carbonyl, carboxyl, amido, amino and ammonium radicals. The aromatic radical, such as a phenyl radical, is linked to the groups CR3R4 via bonds in positions 1,2, 1,3 or 1,4 such as in positions 1,3 and 1,4. If the phenyl radical linked via bonds in positions 1,4 bears one or two substituents, this or these substituent(s) is(are), for example, located in position 1,4 relative to one of the groups CR3R4. If the phenyl radical linked via bonds in positions 1,3 bears one or two substituents, this or these substituent(s) is (are), for example, located in position 1 and/or 3 relative to one of the groups CR3R4. In the case where the radical is diaromatic, it is, for example, non-fused and comprises two phenyl radicals possibly separated with a single bond (i.e., a carbon of each of the two rings) or with an alkyl radical, such as of CH2 or C(CH3)2 type. In one embodiment, the aromatic radicals do not bear a substituent. It should be noted that the diaromatic radical is linked to the groups CR3R4 via bonds in positions 4,4′. The groups X that are suitable may be chosen, for example, from linear and branched alkyl radicals comprising from 1 to 13 carbon atoms, such as methylene, ethylene, propylene, isopropylene, n-butylene, pentylene and hexylene; 2-hydroxypropylene and 2-hydroxy-n-butylene; C1-C13 alkylene radicals substituted or interrupted with at least one entity chosen from nitrogen and oxygen atoms, and groups bearing at least one hetero atom (for example, hydroxyl, amino, ammonium, carbonyl and carboxyl), such as —CH2CH2OCH2CH2—, 1,6-dideoxy-d-mannitol, —CH2N+(CH3)2CH2—, —CH2CH2N+(CH3)2—(CH2)6N+(CH3)2—CH2CH2—, —CO—CO—, 3,3-dimethylpentylene, 2-acetoxyethylene, butylene-1,2,3,4-tetraol; —CH═CH—; aromatic and diaromatic radicals substituted with at least one entity chosen from alkyl radicals, groups bearing at least one hetero atom and halogen atoms, such as 1,4-phenylene, 1,3-phenylene, 1,2-phenylene, 2,6-fluorobenzene, 4,4′-biphenylene, 1,3-(5-methylbenzene), 1,2-bis(2-methoxy)benzene, bis(4-phenyl)methane, methyl 3,4-benzoate and 1,4-bis(amidomethyl)phenyl; radicals of heterocyclic type such as pyridine, and derivatives thereof such as 2,6-bispyridine, imidazole, imidazolium and triazine. In one embodiment, X is chosen from linear and branched C1-C13 alkyl radicals; —CH2CH(OH)CH2—; —CH2CH(Cl)CH2—; —CH2CH2—OCOCH2—; —CH2CH2COOCH2—, -Ra-O-Rb- radicals wherein Ra is chosen from linear C2-C6 alkyl radicals and Rb is chosen from C1-C2 alkyl radicals; Rc-N(Rd)-Re- radicals wherein Rc is chosen from C2-C9 alkyl radicals, Rd is chosen from a hydrogen atom and C1-C2 alkyl radicals and Re is chosen from C1-C6 alkyl radicals; -Rf-N+(Rg)2-Rh- radicals wherein Rf is chosen from linear C2-C9 alkyl radicals, Rg, which may be identical or different, (for example, which are identical), are each chosen from C1-C2 alkyl radicals and Rh is chosen from linear C1-C6 alkyl radicals; and —CO—CO—. X may furthermore be chosen, for example, from imidazole radicals, optionally substituted with at least one alkyl radical chosen from alkyl radicals comprising from 1 to 14 carbon atoms, such as from 1 to 10 carbon atoms and further such as from 1 to 4 carbon atoms, for example, the divalent radicals having the following formula (III): wherein Ri and Rj, which may be identical or different, are each chosen from linear C1-C6 alkyl radicals; X may similarly be chosen, for example, from the divalent triazine-based radicals below: In one embodiment, X may be chosen from the divalent aromatic radicals below: In the formula (F3) of these fluorescent compounds, Y− is an anion chosen from organic and mineral anions. If there are several anions Y−, these anions may be identical or different. Among the anions of mineral origin that may be mentioned, examples include anions derived from halogen atoms, such as chlorides and iodides, sulphates and bisulphates, nitrates, phosphates, hydrogen phosphates, dihydrogen phosphates, carbonates and bicarbonates. Among the anions of organic origin that may be mentioned, examples include anions derived from the salts of saturated or unsaturated, aromatic or non-aromatic monocarboxylic or polycarboxylic, sulphonic or sulphuric acids, optionally substituted with at least one entity chosen from hydroxyl and amino radicals, and halogen atoms. Non-limiting examples that are suitable for use include acetates, hydroxyacetates, aminoacetates, (tri)chloroacetates, benzoxyacetates, propionates and derivatives bearing at least one chlorine atom, fumarates, oxalates, acrylates, malonates, succinates, lactates, tartrates, glycolates, citrates, benzoates and derivatives bearing at least one radical chosen from methyl and amino radicals, alkyl sulphates, tosylates, benzenesulphonates, toluene-sulphonates, etc. In one embodiment, Y−, which may be identical or different, are each chosen from chloride, sulphate, methosulphate and ethosulphate. Finally, the integer n is at least equal to 2 and at most equal to the number of cationic charges present in the fluorescent compound. For example, the fluorescent compounds that have just been described in detail are symmetrical compounds. These compounds may be synthesized by reacting, in a first step, α-picoline with a reagent comprising two leaving groups that may be chosen from halogen atoms, such as bromine and chlorine, or groups of tolylsulphonyl or methanesulphonyl type. This first step may take place in the presence of a solvent, for instance dimethylformamide. The number of moles of α-picoline is generally in the range of 2 per mole of reagent comprising the leaving groups. In addition, the reaction is usually performed at the reflux temperature of the reagent and/or of the solvent if a solvent is present. The product derived from this first step is then placed in contact with a corresponding aldehyde having the following formula: wherein R1, R2 and R6 have the same meanings as indicated above in the formula (F3). In this case, the reaction may be performed in the presence of a suitable solvent, which is, for example, at reflux. The radicals R1 and R2 of the aldehyde may have the meaning indicated in the formula (F3) described previously. It is also possible to use an aldehyde wherein the radicals R1 R2 and R6 are hydrogen atoms and to perform, in accordance with standard methods, the substitution of these hydrogen atoms with suitable radicals as described in the general formula once the second step is complete. Reference may be made, for example, to syntheses as described in U.S. Pat. No. 4,256,458. The at least one fluorescent dye present in the composition disclosed herein may range, for example, from 0.01% to 20% by weight, such as from 0.05% to 10% by weight, and further such as from 0.1% to 5% by weight, relative to the total weight of the composition. The cosmetically acceptable medium generally comprises water or a mixture of water and at least one organic solvent chosen from common organic solvents. Among the solvents that are suitable for use, mention may be made, for example, of alcohols such as ethyl alcohol, isopropyl alcohol, benzyl alcohol and phenylethyl alcohol, glycols and glycol ethers, for instance ethylene glycol monomethyl ether, monoethyl ether and monobutyl ether, propylene glycol and ethers thereof, for instance propylene glycol monomethyl ether, butylene glycol, dipropylene glycol and diethylene glycol alkyl ethers, for instance diethylene glycol monoethyl ether and monobutyl ether, and polyols, for instance glycerol. Polyethylene glycols and polypropylene glycols, and mixtures of all these compounds, may also be used. The at least one solvent, if present, is in an amount ranging, for example, from 1% to 40% by weight such as from 5% to 30% by weight relative to the total weight of the composition. The pH of the composition disclosed herein ranges, for example, from 3 to 12, such as from 5 to 11. It may be adjusted to the desired value by means of acidifying or basifying agents. Examples of acidifying agents that may be mentioned include mineral or organic acids, for instance hydrochloric acid, orthophosphoric acid, sulphuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid and lactic acid, and sulphonic acids. Examples of basifying agents that may be mentioned include aqueous ammonia, alkaline carbonates, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine and derivatives thereof, sodium hydroxide, potassium hydroxide and the compounds of formula (A) below: wherein W is a propylene residue optionally substituted with at least one entity chosen from a hydroxyl group and C1-C6 alkyl radicals; R1 R2, R3 and R4, which may be identical or different, are each chosen from a hydrogen atom and C1-C6 alkyl and C1-C6 hydroxyalkyl radicals. In one embodiment, the composition may comprise, in addition to the at least one fluorescent dye, at least one additional non-fluorescent direct dye chosen from those of nonionic, cationic or anionic nature, which may be chosen, for example, from nitrobenzene dyes. The following red or orange nitrobenzene direct dyes are, for example, suitable for use: 1-hydroxy-3-nitro-4-N-(γ-hydroxypropyl)aminobenzene, N-(β-hydroxyethyl)amino-3-nitro-4-aminobenzene, 1-amino-3-methyl-4-N-(β-hydroxyethyl)amino-6-nitrobenzene, 1-hydroxy-3-nitro-4-N-(β-hydroxyethyl)aminobenzene, 1,4-diamino-2-nitrobenzene, 1-amino-2-nitro-4-methylaminobenzene, N-(β-hydroxyethyl)-2-nitro-para-phenylenediamine, 1-amino-2-nitro-4-(β-hydroxyethyl)amino-5-chlorobenzene, 2-nitro-4-aminodiphenylamine, 1-amino-3-nitro-6-hydroxybenzene, 1-(β-aminoethyl)amino-2-nitro-4-(β-hydroxyethyloxy)benzene, 1-(β,γ-dihydroxypropyl)oxy-3-nitro-4-(β-hydroxyethyl)aminobenzene, 1-hydroxy-3-nitro-4-aminobenzene, 1-hydroxy-2-amino-4,6-dinitrobenzene, 1-methoxy-3-nitro-4-(β-hydroxyethyl)aminobenzene, 2-nitro-4′-hydroxydiphenylamine, and 1-amino-2-nitro-4-hydroxy-5-methylbenzene. The composition disclosed herein may also comprise, in addition to or in replacement for these nitrobenzene dyes, at least one additional direct dye chosen from yellow, green-yellow, blue and violet nitrobenzene dyes, azo dyes, anthraquinone, naphthoquinone and benzoquinone dyes, indigoid dyes, and triarylmethane-based dyes. The at least one additional direct dye may, for example, be chosen from basic dyes, among which mention may be made, for example, of the dyes known in the Color Index, 3rd edition, under the names “Basic Brown 16”, “Basic Brown 17”, “Basic Yellow 57”, “Basic Red 76”, “Basic Violet 10”, “Basic Blue 26” and “Basic Blue 99”, and acidic direct dyes, among which mention may be made, for example, of the dyes known in the Color Index, 3rd edition, under the names “Acid Orange 7”, “Acid Orange 24”, “Acid Yellow 36”, Acid Red 33”, “Acid Red 184”, “Acid Black 2”, “Acid Violet 43” and “Acid Blue 62”, and cationic direct dyes such as those described in patent applications WO 95/01772, WO 95/15144 and EP-A-0 714 954. Among the additional yellow and green-yellow nitrobenzene direct dyes that may be mentioned, for example, are the compounds chosen from: 1-β-hydroxyethyloxy-3-methylamino-4-nitrobenzene, 1-methylamino-2-nitro-5-(β,γ-dihydroxypropyl)oxybenzene, 1-(β-hydroxyethyl)amino-2-methoxy-4-nitrobenzene, 1-(β-aminoethyl)amino-2-nitro-5-methoxybenzene, 1,3-di(β-hydroxyethyl)amino-4-nitro-6-chlorobenzene, 1-amino-2-nitro-6-methylbenzene, 1-(β-hydroxyethyl)amino-2-hydroxy-4-nitrobenzene, N-(β-hydroxyethyl)-2-nitro-4-trifluoromethylaniline, 4-(β-hydroxyethyl)amino-3-nitrobenzenesulphonic acid, 4-ethylamino-3-nitrobenzoic acid, 4-(β-hydroxyethyl)amino-3-nitrochlorobenzene, 4-(β-hydroxyethyl)amino-3-nitromethylbenzene, 4-(β,γ-dihydroxypropyl)amino-3-nitrotrifluoromethylbenzene, 1-(β-ureidoethyl)amino-4-nitrobenzene, 1,3-diamino-4-nitrobenzene, 1-hydroxy-2-amino-5-nitrobenzene, 1-amino-2-[tris(hydroxymethyl)methyl]amino-5-nitrobenzene, 1-(β-hydroxyethyl)amino-2-nitrobenzene, and 4-(β-hydroxyethyl)amino-3-nitrobenzamide. Among the additional blue or violet nitrobenzene direct dyes that may be mentioned, for example, are the compounds chosen from: 1-(β-hydroxyethyl)amino-4-N,N-bis(β-hydroxyethyl)amino-2-nitrobenzene, 1-(γ-hydroxypropyl)amino-4,N,N-bis(β-hydroxyethyl)amino-2-nitrobenzene, 1-(β-hydroxyethyl)amino-4-(N-methyl-N-β-hydroxyethyl)amino-2-nitrobenzene, 1-(β-hydroxyethyl)amino-4-(N-ethyl-N-β-hydroxyethyl)amino-2-nitrobenzene, 1-(β,γ-dihydroxypropyl)amino-4-(N-ethyl-N-β-hydroxyethyl)amino-2-nitrobenzene, 2-nitroparaphenylenediamines having the following formula: wherein: R6 is chosen from C1-C4 alkyl radicals, and β-hydroxyethyl, β-hydroxypropyl and γ-hydroxypropyl radicals; R5 and R7, which may be identical or different, are each chosen from β-hydroxyethyl, β-hydroxypropyl, γ-hydroxypropyl and β,γ-dihydroxypropyl radicals, provided that at least one of the radical chosen from radicals R5, R6 and R7 is a γ-hydroxypropyl radical and R6 and R7 are not simultaneously able to denote a β-hydroxyethyl radical when R6 is a γ-hydroxypropyl radical, such as those described in the document FR 2 692 572. When present, the at least one additional direct dye is present in an amount ranging, for example, from 0.0005% to 12% by weight, such as from 0.005% to 6% by weight relative to the total weight of the composition. When it is intended for oxidation dyeing, the composition disclosed herein comprises, in addition to the at least one fluorescent dye, at least one oxidation base chosen from the oxidation bases conventionally used for oxidation dyeing and among which mention may be made, for example, of para-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, ortho-aminophenols and heterocyclic bases, and the acid or base addition salts thereof. Among the para-phenylenediamines that may be mentioned, for example, are para-phenylenediamine, para-tolylenediamine, 2-chloro-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,5-dimethyl-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine, N,N-diethyl-para-phenylenediamine, N,N-dipropyl-para-phenylenediamine, 4-amino-N,N-diethyl-3-methylaniline, N,N-bis(β-hydroxyethyl)-para-phenylenediamine, 4-N,N-bis(β-hydroxyethyl)amino-2-methylaniline, 4-N,N-bis(β-hydroxyethyl)amino-2-chloroaniline, 2-β-hydroxyethyl-para-phenylenediamine, 2-fluoro-para-phenylenediamine, 2-isopropyl-para-phenylenediamine, N-(β-hydroxypropyl)-para-phenylenediamine, 2-hydroxymethyl-para-phenylenediamine, N,N-dimethyl-3-methyl-para-phenylenediamine, N-ethyl-N-(β-hydroxyethyl)-para-phenylenediamine, N-(β,γ-dihydroxypropyl)-para-phenylenediamine, N-(4′-aminophenyl)-para-phenylenediamine, N-phenyl-para-phenylenediamine, 2-β-hydroxyethyloxy-para-phenylenediamine, 2-β-acetylaminoethyloxy-para-phenylenediamine, N-(β-methoxyethyl)-para-phenylenediamine and 4′-aminophenyl-1-(3-hydroxy)pyrrolidine, and the acid or base addition salts thereof. Among the para-phenylenediamines mentioned above, examples include para-phenylenediamine, para-tolylenediamine, 2-isopropyl-para-phenylenediamine, 2-β-hydroxyethyl-para-phenylenediamine, 2-β-hydroxyethyloxy-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, N,N-bis(β-hydroxyethyl)-para-phenylenediamine, 2-chloro-para-phenylenediamine and 2-β-acetylaminoethyloxy-para-phenylenediamine, and the acid or base addition salts thereof. Among the bis(phenyl)alkylenediamines that may be mentioned, for example, are N,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)-1,3-diaminopropanol, N,N ′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)ethylenediamine, N,N′-bis(4-aminophenyl)tetramethylenediamine, N,N′-bis(β-hydroxyethyl)-N,N′-bis(4-aminophenyl)tetramethylenediamine, N,N′-bis(4-methylaminophenyl)tetramethylenediamine, N,N′-bis(ethyl)-N,N′-bis(4′-amino-3′-methylphenyl)ethylenediamine and 1,8-bis(2,5-diaminophenoxy)-3,5-dioxaoctane, and the acid or base addition salts thereof. Among the para-aminophenols that may be mentioned, for example, are para-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol, 4-amino-3-hydroxymethylphenol, 4-arriino-2-methylphenol, 4-amino-2-hydroxymethylphenol, 4-amino-2-methoxymethylphenol, 4-amino-2-aminomethylphenol, 4-amino-2-(β-hydroxyethylaminomethyl)phenol and 4-amino-2-fluorophenol, and the acid or base addition salts thereof. Among the ortho-aminophenols that may be mentioned, for example, are 2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol and 5-acetamido-2-aminophenol, and the acid or base addition salts thereof. Among the heterocyclic bases that may be mentioned, for example, are pyridine derivatives, pyrimidine derivatives and pyrazole derivatives, and the acid or base addition salts thereof. When present, the at least one oxidation base is present in an amount ranging, for example, from 0.0005% to 12% by weight, such as from 0.005% to 6% by weight relative to the total weight of the composition. When it is intended for oxidation dyeing, the composition disclosed herein may also comprise, in addition to the at least one fluorescent dye and the at least one oxidation base, at least one coupler so as to modify or to enrich with glints the shades obtained using the at least one fluorescent dye and the at least one oxidation base. The at least one coupler that may be used in the composition disclosed herein may be chosen from the couplers conventionally used in oxidation dyeing, and among which mention may be made, for example, of meta-phenylenediamines, meta-aminophenols, meta-diphenols and heterocyclic couplers, and the acid or base addition salts thereof. The at least one coupler disclosed herein may be, for example, chosen from 2-methyl-5-aminophenol, 5-N-(β-hydroxyethyl)amino-2-methylphenol, 3-aminophenol, 1,3-dihydroxybenzene, 1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene, 2,4-diamino-1-(β-hydroxyethyloxy)benzene, 2-amino-4-(β-hydroxyethylamino)-1-methoxybenzene, 1,3-diaminobenzene, 1,3-bis(2,4-diaminophenoxy)propane, sesamol, α-naphthol, 6-hydroxyindole, 4-hydroxyindole, 4-hydroxy-N-methylindole, 6-hydroxyindoline, 2,6-dihydroxy-4-methylpyridine, 1H-3-methylpyrazol-5-one, 1-phenyl-3-methylpyrazol-5-one, 2,6-dimethylpyrazolo[1,5-b]-1,2,4-triazole, 2,6-dimethyl[3,2-c]-1,2,4-triazole and 6-methylpyrazolo[1,5-a]benzimidazole, and the acid and base addition salts thereof. When present, the at least one coupler is present in an amount ranging from 0.0001% to 10% by weight such as from 0.005% to 5% by weight, relative to the total weight of the composition. In general, the acid addition salts that may be used in the context of the compositions disclosed herein (oxidation bases and couplers) are chosen, for example, from hydrochlorides, hydrobromides, sulphates, citrates, succinates, tartrates, tosylates, benzenesulphonates, lactates and acetates. The base addition salts that may be used in the context of the compositions disclosed herein (oxidation bases and couplers) are chosen, for example, from the addition salts with alkali metals, alkaline-earth metals, ammonia and organic amines, including alkanolamines and the compounds of formula (VIII). The composition disclosed herein may also comprise at least one adjuvant chosen from various conventionally used adjuvants, such as anionic, cationic, nonionic, amphoteric and zwitterionic surfactants and mixtures thereof, anionic, cationic, nonionic, amphoteric andzwitterionic polymers other than those disclosed herein, and mixtures thereof, mineral thickeners, antioxidants, penetrating agents, sequestering agents, fragrances, buffers, dispersants, conditioners, for instance cations, volatile and non-volatile, modified and unmodified silicones, film-forming agents, ceramides, preserving agents, stabilizers and opacifiers. Non-associative organic thickening polymers may also be added. When at least one surfactant is present, such as of nonionic, anionic or amphoteric type, it is present in an amount ranging, for example, from 0.01% to 30% by weight relative to the weight of the composition. Needless to say, a person skilled in the art will take care to select this or these optional additional compound(s) such that the advantageous properties intrinsically associated with the composition disclosed herein are not, or are not substantially, adversely affected by the envisaged addition(s). The composition disclosed herein may be in various forms, such as in the form of liquids, shampoos, creams or gels, or in any other suitable form. In one embodiment, the composition is in the form of a lightening dye shampoo comprising a cosmetically acceptable aqueous medium. In the composition disclosed herein, when at least one oxidation base is used, optionally in the presence of at least one coupler, or when the at least one fluorescent dye is used in the context of a lightening direct dyeing, then the composition disclosed herein may also comprise at least one oxidizing agent. The at least one oxidizing agent may be chosen, for example, from hydrogen peroxide, urea peroxide, alkali metal bromates, persalts such as perborates and persulphates, and enzymes such as peroxidases and two-electron or four-electron oxidoreductases. In one embodiment, the at least one oxidizing agent is chosen from hydrogen peroxide and enzymes. Further disclosed herein is the use of a composition for dyeing a human keratin material with a lightening effect, comprising, in a cosmetically acceptable medium, at least one fluorescent dye that is soluble in the medium and at least one associative polymer chosen from associative polyurethane derivatives, associative cellulose derivatives, associative polyvinyllactam derivatives and associative unsaturated polyacid derivatives. In the context of this use, the at least one fluorescent dye may be chosen from the fluorescent dyes belonging to the following families: naphthalimides; cationic and non-cationic coumarins; xanthenodiquinolizines (such as sulphorhodamines); azaxanthenes; naphtholactams; azlactones; oxazines; thiazines; dioxazines; monocationic or polycationic fluorescent dyes of azo, azomethine and methine types, alone or as mixtures. For example, the compounds of formulae F1, F2 and F3 already described may be used. It is similarly possible to use the compounds of formula (F4) below: wherein R is chosen from methyl and ethyl radicals; R′ is a methyl radical and X− is an anion chosen, for example, from chloride, iodide, sulphate, methosulphate, acetate and perchlorate. An example of a compound of this type that may be mentioned is the Photosensitizing Dye NK-557 sold by the company Ubichem, wherein R is an ethyl radical, R′ is a methyl radical and X− is an iodide. Everything that has been described previously regarding the natures and contents of the various additives present in the composition remains valid and will not be repeated in this section. As used herein, the term “human keratin materials” includes the skin, the hair, the nails, the eyelashes and the eyebrows, such as dark skin and artificially colored or pigmented hair. Further as used herein, the term “dark skin” means a skin whose lightness L* measured in the CIEL L*a*b* system is less than or equal to 45, such as less than or equal to 40, given that L*=0 is equivalent to black and L*=100 is equivalent to white. The skin types corresponding to this lightness are, for example, African skin, afro-American skin, hispano-American skin, Indian skin and North African skin. As used herein, the term “artificially dyed or pigmented hair” means hair whose tone height is less than or equal to 6 (dark blond) such as less than or equal to 4 (chestnut-brown). The lightening of the hair is evaluated by the “tone height”, which characterizes the degree or level of lightening. The notion of “tone” is based on the classification of the natural shades, one tone separating each shade from the shade immediately following or preceding it. This definition and the classification of the natural shades are well known to hairstyling professionals and are published in the book “Sciences des traitements capillaires [Hair treatment sciences]” by Charles Zviak, 1988, published by Masson, pp. 215 and 278. The tone heights range from 1 (black) to 10 (light blond), one unit corresponding to one tone; the higher the figure, the lighter the shade. Further disclosed herein is a process for dyeing human keratin fibers with a lightening effect, comprising: a) applying to the keratin fibers a composition disclosed herein for a time that is sufficient to develop the desired coloration and lightening, b) optionally rinsing the keratin fibers, c) optionally washing the keratin fibers with shampoo and optionally rinsing the keratin fibers, d) drying the keratin fibres or leaving the keratin fibers to dry. Also disclosed herein is a process for coloring dark skin with a lightening effect, comprising applying to the skin a composition disclosed herein and drying the skin leaving the skin to dry. Everything that has been described previously regarding the various constituent components of the composition remains valid, and reference may be made thereto. For example, the processes disclosed herein are suitable for treating human keratin fibers, such as artificially colored and pigmented hair, or dark skin. In one embodiment, the keratin fibers that may be treated with the process as disclosed herein have a tone height of less than or equal to 6 (dark blond) such as less than or equal to 4 (chestnut-brown). Furthermore, a dark skin capable of being treated in accordance with the disclosure has a lightness L*, measured in the CIEL L*a*b* system, of less than or equal to 45 such as less than or equal to 40. In a first embodiment, the process of dyeing fibers with a lightening effect is performed with a composition that does not comprise any oxidation dyes or coupler and in the absence of oxidizing agent. In a second embodiment, the process of dyeing fibers with a lightening effect is performed with a composition that does not comprise any oxidation dyes or coupler, but in the presence of at least one oxidizing agent. According to one embodiment of the dyeing process disclosed herein, at least one composition as defined above is applied to the keratin fibers, such as the hair, for a time that is sufficient to develop the desired coloration and lightening, after which the fibers are rinsed, optionally washed with shampoo, rinsed again and dried. According to a second embodiment of the dyeing process disclosed herein, at least one composition as defined above is applied to the keratin fibers, such as the hair, without final rinsing. According to a third embodiment of the dyeing process disclosed herein, the dyeing process comprises a preliminary operation comprising separately storing, on the one hand, a composition disclosed herein comprising, in addition to the at least one fluorescent dye and the at least one associative polymer, optionally at least one oxidation base and/or at least one coupler, and, on the other hand, a composition comprising, in a cosmetically acceptable medium, at least one oxidizing agent, then mixing them together at the time of use, and applying to the keratin fibers, such as the hair, the mixture for a time that is sufficient to develop the desired coloration, rinsing the keratin fibers, optionally washing the keratin fibers with shampoo, rinsing again and drying the keratin fibers. The time required to develop the coloration and to obtain the lightening effect on the keratin fibers, such as the hair, may range from 5 to 60 minutes, such as from 5 to 40 minutes. The temperature required to develop the coloration and to obtain the lightening effect may range from room temperature (15 to 25° C.) to 80° C., such as from 15 to 40° C. Also disclosed herein is a multi-compartment device for dyeing keratin fibers, such as the hair, with a lightening effect, comprising at least one compartment comprising a composition disclosed herein, and at least one other compartment comprising a composition comprising at least one oxidizing agent. This device may be equipped with a means for applying the desired mixture to the keratin fibers, such as the devices described in French Patent No. 2 586 913. It should be noted that the composition disclosed herein, if used to treat keratin fibers, such as chestnut-brown hair, makes it possible to achieve the following results: If the reflectance of the hair is measured when it is irradiated with visible light in the wavelength range from 400 to 700 nanometers, and if the curves of reflectance as a function of the wavelength are compared for hair treated with the composition disclosed herein and untreated hair, it is found that the reflectance curve corresponding to the treated hair, in a wavelength range from 500 to 700 nanometers, is higher than that corresponding to the untreated hair. This means that, in the wavelength range from 500 to 700 nanometers, such as from 540 to 700 nanometers, there is at least one range in which the reflectance curve corresponding to the treated hair is higher than the reflectance curve corresponding to the untreated hair. The term “higher than” means a difference of at least 0.05%, such as a difference of at least 0.1% of reflectance. However, there may be, within the wavelength range from 500 to 700 nanometers such as from 540 to 700 nanometers, one or more ranges in which the reflectance curve corresponding to the treated fibers is either superimposable on or lower than the reflectance curve corresponding to the untreated fibers. In one embodiment, the wavelength at which the difference is maximal between the reflectance curve for the treated hair and that for the untreated hair is in the wavelength range from 500 to 650 nanometers such as in the wavelength range from 550 to 620 nanometers. In addition, the composition disclosed herein is, for example, capable of lightening the hair and the skin in a shade which, measured in the CIEL L*a*b* system, has a variable b* of greater than or equal to 6, with a b*/absolute value of a* ratio of greater than 1.2 according to the selection test described below. Selection Test The composition is applied to chestnut-brown keratin fibers, such as the hair, at a rate of 10 grams of composition per 1 gram of chestnut-brown fibers. The composition is spread on so as to cover all of the fibers. The composition is left to act for 20 minutes at room temperature (20 to 25° C.). The fibers are then rinsed with water and then washed with a shampoo based on lauryl ether sulphate. They are then dried. The spectrocolorimetric characteristics of the fibers are then measured in order to determine the L*a*b* coordinates. In the CIEL L*a*b* system, a* and b* indicate two color axes: a* indicates the green/red color axis (+a* is red, −a* is green) and b* indicates the blue/yellow color axis (+b* is yellow and −b* is blue); values close to zero for a* and b* correspond to grey shades. Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. The examples that follow are intended to illustrate the disclosure without, however, limiting its scope. EXAMPLES Fluorescent Compound 93 g of 2-picoline were reacted with 120 g of 1,6-dibromohexane in dimethylformamide at 110° C. for 5 hours. The precipitated product was recovered and filtered off. 109 g of the product obtained above were dissolved in methanol and 82.82 g of p-dimethylaminobenzaldehyde were added in two portions, in the presence of pyrrolidine. The mixture was then left for 30 minutes. The product was recovered in precipitated form. Analysis by mass spectroscopy: 266. Elemental analysis: C, 62.43%; H, 6.40%; Br, 23.07%; N, 8.09%. The formula is as follows: C36H44N4.2Br. Compositions Composition 1 2 Fluorescent compound 1% 1% Aculyn 44 (*) 0.5% — Styleze W20 (**) — 0.5% Distilled water qs 100% qs 100% (*) associative polyurethane derivative (**) associative polyvinyllactam derivative The percentages are expressed by weight of active material. Coloration The compositions were each applied to a lock of natural chestnut-brown hair (tone height 4) with a leave-in time of 20 minutes. The locks were then rinsed and dried under a hood for 30 minutes. A marked lightening effect was observed on the locks. | 20040401 | 20070424 | 20050210 | 68296.0 | 0 | ELHILO, EISA B | COMPOSITION FOR DYEING HUMAN KERATIN MATERIALS, COMPRISING AT LEAST ONE FLUORESCENT DYE AND AT LEAST ONE ASSOCIATIVE POLYMER, PROCESS THEREFOR AND USE THEREOF | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,324 | ACCEPTED | COOLING WATER SCALE AND CORROSION INHIBITION | A methods for inhibiting silica scale formation and corrosion in aqueous systems where soluble silica (SiO2) can be maintained at residuals below 200 mg/L, but more preferably maintained at greater than 200 mg/L as SiO2, without silica scale and with control of deposition of source water silica accumulations as high as 4000 mg/L (cycled accumulation) from evaporation and concentration of source water. The methods of the present invention also provide highly effective inhibition of corrosion for carbon steel, copper, copper alloy, and stainless steel alloys. The methods of the present invention comprise pretreatment removal of hardness ions from the makeup source water, maintenance of electrical conductivity, and elevating the pH level of the aqueous environment. Thereafter, specified water chemistry residual ranges are maintained in the aqueous system to achieve inhibition of scale and corrosion. | 1. A method for controlling silica or silicate scale formation in an aqueous heat transfer water system with silica contributed by source water, the methods of the present invention comprising the steps: a) removing hardness ions from said source water; b) controlling the conductivity of said aqueous system water such that said aqueous system water possesses a measurable conductivity of at least 1 μmhos; c) elevating and maintaining the pH of said aqueous system water such that said aqueous system water possesses a pH of approximately 9.0 or greater; and d) providing a metallic heat transfer surface and cyclically contacting said aqueous system water thereabout. 2. The method of claim 1 wherein in step a), said hardness ions comprise ions of calcium and magnesium. 3. The method of claim 1 wherein said aqueous system water contains soluble SiO2 residual that is at least 125 mg/L. 4. The method of claim 3 wherein said aqueous system water contains soluble SiO2 in excess of 200 mg/L. 5. The methods of the present invention of claim 3 wherein in step a), said hardness ions are removed in amounts equal to or less than approximately 20% of the SiO2 present within said source water. 6. The methods of the present invention of claim 3 wherein in step a), said hardness ions are removed in amounts equal to or less than approximately 5% of the SiO2 present within said source water. 7. The method of claim 1 wherein in step c), said pH is maintained at 9.6 or higher. 8. The method of claim 1 wherein in step a), said hardness ions are removed via a method selected from the group consisting of ion exchange, selective ion removal with reverse osmosis, reverse osmosis, electro chemical removal, chemical precipitation, evaporation and distillation. 9. The method of claim 1 wherein in step c), said pH is increased by adding an alkali agent. 10. The method of claim 9 wherein said alkali agent comprises sodium hydroxide. 11. The method of claim 1 wherein in step c), said pH is elevated by evaporating a portion of said aqueous system water. 12. The method of claim 1 wherein in step c), said pH is elevated by distilling a portion of said aqueous system water. 13. The method of claim 1 wherein in step c), said aqueous heat transfer water system comprises water utilized for cooling processes, water utilized for cooling tower systems, water utilized for evaporative cooling, water utilized for cooling lakes or ponds, water utilized for enclosed or secondary cooling and heating loops. 14-26. (canceled) 27. The method of claim 1 wherein prior to step a), said methods of the present invention comprises the step: a) analyzing said source water to determine the concentration of SiO2 present therein. 28. (canceled) 29. The method of claim 1 wherein in step b), said conductivity of said aqueous system water is controlled such that said aqueous system water possesses a conductivity of at least 500 μmhos. 30. (canceled) 31. The method of claim 1, wherein said source water contains silica in an amount of 4000 mg/L or less. 32. (canceled) | CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part of U.S. patent application (Ser. No. not yet assigned) filed on Jan. 9, 2004, entitled Cooling Water Scale and Corrosion Inhibition. STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT Not Applicable BACKGROUND OF THE INVENTION Silica is one of the major scale and fouling problems in many processes using water. Silica is difficult to deal with because it can assume many low solubility chemical forms depending on the water chemistry and metal surface temperature conditions. Below about pH 9.0, monomeric silica has limited solubility (125-180 mg/L as SiO2) and tends to polymerize as these concentrations are exceeded to form insoluble (amorphous) oligomeric or colloidal silica. At higher pH, particularly above about pH 9.0, silica is soluble at increased concentrations of the monomeric silicate ion or in the multimeric forms of silica. Since conversion can be slow, all of these forms may exist at any one time. The silicate ion can react with polyvalent cations like magnesium and calcium commonly present in process waters to produce salts with very limited solubility. Thus it is common for a mixture of many forms to be present: monomeric, oligomeric and colloidal silica; magnesium silicate, calcium silicate and other silicate salts. In describing this complex system, it is common practice to refer to the mixture merely as silica or as silica and silicate. Herein these terms are used interchangeably. To address such problem, methods for controlling deposition and fouling of silica or silicate salts on surfaces in a aqueous process have been derived and include: 1) inhibiting precipitation of the material from the process water; 2) dispersing precipitated material after it has formed in the bulk water; 3) maintaining an aqueous chemical environment that supports formation of increased residuals of soluble silica species; and 4) producing a non-adherent form of silica precipitants in the bulk water. The exact mechanism by which specific scale inhibition methods of the present inventions function is not well understood. In industrial application, most scale and corrosion control methods used in aqueous systems typically rely on the addition of a scale and corrosion inhibitor in combination with controlled wastage of system water to prevent scale and corrosion problems. In this regard, the major scale formation potentials are contributed by the quantity of hardness (calcium and magnesium) and silica ions contributed by the source water, while the major corrosive potential results from the ionic or electrolytic strength in the system water. Treatment methods to minimize corrosion have further generally relied on the addition of chemical additives that inhibit corrosion through suppression of corrosive reactions occurring at either the anode or the cathode present on the metal surface, or combinations of chemical additives that inhibit reactions at both the anode and cathode. The most commonly applied anodic inhibitors include chromate, molybdate, orthophosphate, nitrite and silicate whereas the most commonly applied cathodic inhibitors include polyphosphate, zinc, organic phosphates and calcium carbonate. In view of toxicity and environmental concerns, the use of highly effective heavy metal corrosion inhibitors, such as chromate, have been strictly prohibited and most methods now rely on a balance of the scale formation and corrosive tendencies of the system water and are referred to in the art as alkaline treatment approaches. This balance, as applied in such treatment approaches, is defined by control of system water chemistry with indices such as LSI or Ryznar, and is used in conjunction with combinations of scale and corrosion inhibitor additives to inhibit scale formation and optimize corrosion protection at maximum concentration of dissolved solids in the source water. These methods, however, are still limited by the maximum concentration of silica and potential for silicate scale formation. Moreover, corrosion rates are also significantly higher than those available with use of heavy metals such as chromate. Along these lines, since the use of chromate and other toxic heavy metals has been restricted, as discussed above, corrosion protection has generally been limited to optimum ranges of 2 to 5 mils per year (mpy) for carbon steel when treating typical source water qualities with current corrosion control methods. Source waters that are high in dissolved solids or are naturally soft are even more difficult to treat, and typically have even higher corrosion rates. In an alternative approach, a significant number of methods of the present inventions for controlling scale rely on addition of acid to treated systems to control pH and reduce scaling potentials at higher concentrations of source water chemistry. Such method allows for conservation of water through modification of the concentrated source water, while maintaining balance of the scale formation and corrosive tendencies of the water. Despite such advantages, these methods have the drawback of being prone to greater risk of scale and/or corrosion consequences with excursions with the acid/pH control system. Moreover, there is an overall increase in corrosion potential due to the higher ionic or electrolytic strength of the water that results from addition of acid ions that are concentrated along with ions in the source water. Lower pH corrosion control methods further rely on significantly higher chemical additive residuals to offset corrosive tendencies, but are limited in effectiveness without the use of heavy metals. Silica concentration must still be controlled at maximum residuals by system water wastage to avoid potential silica scaling. In a further approach, source water is pretreated to remove hardness ions in a small proportion of systems to control calcium and magnesium scale potentials. These applications, however, have still relied on control of silica residuals at previous maximum guideline levels through water wastage to prevent silica scale deposits. Corrosion protection is also less effective with softened water due to elimination of the balance of scale and corrosion tendency provided by the natural hardness in the source water. Accordingly, there is a substantial need in the art for methods that are efficiently operative to inhibit corrosion and scale formation that do not rely upon the use of heavy metals, extensive acidification and/or water wastage that are known and practiced in the prior art. There is additionally a need in the art for such processes that, in addition to being efficient, are extremely cost-effective and environmentally safe. Exemplary of those processes that would likely benefit from such methods would include cooling water processes, cooling tower systems, evaporative coolers, cooling lakes or ponds, and closed or secondary cooling and heating loops. In each of these processes, heat is transferred to or from the water. In evaporative cooling water processes, heat is added to the water and evaporation of some of the water takes place. As the water is evaporated, the silica (or silicates) will concentrate and if the silica concentration exceeds its solubility, it can deposit to form either a vitreous coating or an adherent scale that can normally be removed only by laborious mechanical or chemical cleaning. Along these lines, at some point in the above processes, heat is extracted from the water, making any dissolved silicate less soluble and thus further likely to deposit on surfaces, thus requiring removal. Accordingly, a method for preventing fouling of surfaces with silica or silicates, that further allows the use of higher levels of silica/silicates for corrosion control would be exceptionally advantageous. In this respect for cooling water, an inhibition method has long been sought after that would enable silica to be used as a non-toxic and environmentally friendly corrosion inhibitor. To address these specific concerns, the current practice in these particular processes is to limit the silica or silicate concentration in the water so that deposition from these compounds does not occur. For example in cooling water, the accepted practice is to limit the amount of silica or silicates to about 150 mg/L, expressed as SiO2. Reportedly, the best technology currently available for control of silica or silicates in cooling water is either various low molecular weight polymers, various organic phosphate chemistries, and combinations thereof. Even with use of these chemical additives, however, silica is still limited to 180 mg/L in most system applications. Because in many arid areas of the U.S. and other parts of the world make-up water may contain from 50-90 mg/L silica, cooling water can only be concentrated 2 to 3 times such levels before the risk of silica or silicate deposition becomes too great. A method that would enable greater re-use or cycling of this silica-limited cooling water would be a great benefit to these areas. SUMMARY OF THE INVENTION The present invention specifically addresses and alleviates the above-identified deficiencies in the art. In this regard, the invention relates to methods for controlling silica and silicate fouling problems, as well as corrosion of system metallurgy (i.e. metal substrates) in aqueous systems with high concentrations of dissolved solids. More particularly, the invention is directed to the removal of hardness ions from the source water and control of specified chemistry residuals in the aqueous system to inhibit deposition of magnesium silicate and other silicate and silica scales on system surfaces, and to inhibit corrosion of system metallurgy. To that end, we have unexpectedly discovered that the difficult silica and silicate scaling problems that occur in aqueous systems when silica residuals exceed 125 mg/L, and more preferably are approaching or greater than 200 mg/L as SiO2, to as high as 4000 mg/L of silica accumulation (cycled accumulation from source water), can be controlled by initially removing hardness ions (calcium and magnesium) from the makeup source water (i.e., water fed to the aqueous system) using pretreatment methods of the present inventions known in the art, such as through the use of ion exchange resins, selective ion removal with reverse osmosis, reverse osmosis, electrochemical removal, chemical precipitation, or evaporation/distillation. Preferably, the pretreatment methods of the present invention will maintain the total hardness in the makeup water at less than 20% of the makeup silica residual (mg/L SiO2), as determined from an initial assessment of the source water. In some embodiments, the total hardness ions will be maintained at less than 5% of the makeup silica residual. When source makeup water is naturally soft, with less than 10 mg/L hardness as CaCO3, pretreatment removal of hardness ions may be bypassed in some systems. Thereafter, the conductivity (non-neutralized) in the aqueous system is controlled such that the same is maintained at some measurable level (i.e., at least 1 μmhos and the pH of the source water elevated to a pH of approximately 9.0, and preferably 9.6, or higher. With respect to the latter, the pH may be adjusted by the addition of an alkaline agent, such as sodium hydroxide, or by simply removing a portion of the aqueous system water through such well known techniques or processes as evaporation and/or distillation. In a related application, we have unexpectedly discovered that the excessive corrosion of carbon steel, copper, copper alloys, and stainless steel alloys in aqueous systems due to high ionic strength (electrolytic potential) contributed by dissolved solids source water or highly cycled systems can likewise be controlled by the methods of the present inventions of the present invention. In such context, the methods of the present invention comprises removing hardness ions (calcium and magnesium) from the makeup source water using known pretreatment methods of the present inventions, such as ion exchange resins, selective ion removal with reverse osmosis, reverse osmosis, electrochemical removal, chemical precipitation, or evaporation/distillation. The pretreatment methods of the present invention will preferably maintain the total hardness ratio in the makeup water at less than 20%, and preferably at least less than 5%, of the makeup silica residual (mg/L SiO2), as determined from an initial analysis of the source water. When source makeup water is naturally soft, with less than 10 mg/L hardness as CaCO3, pretreatment removal of hardness ions may be bypassed in some systems. Thereafter, the conductivity (non-neutralized) in the aqueous system is controlled such that the same is maintained at some measurable level (i.e., at least 1 μmhos). Alkalinity is then controlled as quantified by pH at 9.0 or higher, with a pH of 9.6 being more highly desired in some applications along with control of soluble silica at residual concentrations approaching or exceeding 200 mg/L, but not less than 10 mg/L, with control at more highly desired residuals in some applications approaching or exceeding 300 mg/L as SiO2. With respect to the latter, the SiO2 may be adjusted by the addition of a silica/silicate agent, such as sodium silicate, or by simply removing a portion of the aqueous system water through such well known techniques or processes as evaporation and/or distillation. DETAILED DESCRIPTION OF THE INVENTION The detailed description set forth below is intended as a description of the presently preferred embodiment of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the functions and sequences of steps for constructing and operating the invention. It is to be understood, however, that the same or equivalent functions and sequences may be accomplished by different embodiments and that they are also intended to be encompassed within the scope of the invention. According to the present invention, there is disclosed methods for inhibiting silica and silicate scale in aqueous systems and providing exceptional metal corrosion protection that comprise the removal of hardness from the makeup source water prior to being fed into the aqueous system and thereafter controlling the aqueous system within specified water chemistry control ranges. Specifically, hardness ions (calcium and magnesium) are removed from the makeup source water using pretreatment methods known in the art, which include methods such as ion exchange resins, selective ion removal with reverse osmosis, reverse osmosis, electrochemical removal, chemical precipitation, or evaporation/distillation. Multivalent metal ions such as those from iron, copper, zinc, barium, and aluminum are usually at low concentrations in treated municipal and well source waters used for make up to cooling systems. These low level concentrations will not typically require removal if the total concentration of these metals in addition to hardness ions (calcium and magnesium) following pretreatment are below the maximum ratio specified based on source water silica residual. However, some water sources such as well, reclaimed or untreated surface waters may have higher residuals of these metals as well as other objectionable materials. Such waters may require pretreatment with alternative methods for reduction of these multivalent metal ions in addition to the pretreatment methods specified by the method for removal of calcium and magnesium multivalent metal ions. The pretreatment methods will preferably maintain the total hardness ratio in the makeup water at less than 20% of the makeup silica residual (mg/L SiO2). In a more highly preferred embodiment, the pretreatment methods will maintain the total hardness ions present in the makeup water at less than 5% of the makeup silica residual. As will be appreciated by those skilled in the art, the silica residual can be readily determined by utilizing known techniques, and will preferably be determined prior to the application of the methods of the present invention. Along these lines, when source makeup water is naturally soft, with less than 10 mg/L hardness as CaCO3, pretreatment removal of hardness ions may be bypassed in some systems. Conductivity (non-neutralized) is established in the aqueous system such that at least some measurable conductivity is present, which is defined as at least 1 μmhos and preferably at least 500 μmhos. Control of conductivity may be conducted through control or elimination of blowdown wastage from the system. In a more highly preferred embodiment, conductivity will be maintained between 10,000 and 150,000 μmhos. Conductivity levels attained in method treated systems will depend upon system capability to concentrate source water, level of dissolved solids (conductivity) in the pre-treated or natural source water, and potential addition of adjunct alkalinity or chemical to attain required control residuals. The higher level of ionic strength in the more highly preferred embodiment control range of 10,000 to 150,000 μmhos will increase the solubility of multivalent metal salts that are less soluble at lower ionic strengths of other methods of the present inventions. This residual control parameter also provides indirect control of silica and alkalinity (pH) residuals contributed by concentration of available silica and alkalinity in the pre-treated or natural source water or by addition of adjunct forms of these chemicals. Aqueous system pH is maintained at 9.0 or greater as contributed by the cycled accumulation of alkalinity from the source water or through supplemental addition of an alkalinity adjunct, such as sodium hydroxide, to the system when required. The minimum pH will provide increased solubility of silica and control of silicate scale and support corrosion protection for metals. Along these lines, in certain preferred embodiments of the present invention, the pH may be raised and maintained to a level of 9.6 of higher. To support corrosion inhibition, soluble silica residuals will preferably be maintained in the aqueous system at levels approaching or exceeding 200 mg/L, but not less than 10 mg/L, as contributed by the cycled accumulation of silica from the source water or through supplemental addition of adjunct forms of silica to the system when required. In certain applications, such levels may be maintained at levels of greater than 300 mg/L. A 200 mg/L minimum residual of soluble silica will support corrosion inhibition for metals, and more particularly, inhibit corrosion of carbon steel to less than 0.3 mpy and less than 0.1 mpy for copper, copper alloys and stainless steel alloys present in the aqueous system. The method will control carbon steel corrosion at less than 5 mpy (less than 0.3 mpy for copper) in treated systems controlled at silica residuals less than 200 mg/l (as SiO2), with reduction of source water multivalent metal ions (hardness) to specified residuals and pH control at 9.0 or greater. With respect to the mechanisms by which the methods of the present inventions effectively achieve their results, excess source water silica (beyond the soluble residuals attained with specified pH control) is probably adsorbed as non-adherent precipitates that form following reaction with small amounts of metals (Ca, Mg, Fe, Al, Zn) or solids introduced by source water or scrubbed from the air by the tower system. This is the probable result of the expanded solubility of the monomeric and multimeric species of silica with the methods of the present invention that impede polymerization of excess silica until it reacts with these incrementally introduced adsorption materials to form small quantities of non-adherent precipitants. The adsorption and precipitation of high ratios of silica on small amounts of solids such as magnesium hydroxide has been demonstrated by the Freundlich isotherms, and is common experience in water treatment chemical precipitation processes. The small quantity of precipitate is removed from the circulating water through settling in the tower basin or drift losses. Control of the lower solubility hardness scale formations and resultant nucleation sites on cooling system surfaces are controlled with the methods disclosed herein, through pretreatment removal of the majority of the scale forming (hardness) metal ions and control of system water at the specified higher ionic strength control ranges. The higher level of ionic strength in the preferred control range increases the solubility of scale forming metal salts. Such approach is well suited to address a further complication in controlling silica and silicate fouling brought about from the phenomena that colloidal silica tends to be more soluble as temperature is raised, while the polyvalent metal salts of the silicate ion tend to be less soluble with increasing temperature. As a result, control or minimization of polyvalent metals in the aqueous solution will prohibit formation of the insoluble salts on heat transfer surfaces, and promote increased solubility of other forms of silica at the elevated temperatures of heat transfer surfaces. The present methods thereby eliminate potential reaction of insoluble silica forms with hardness scale or metal salt deposits on system surfaces and their nucleation sites that initiate silica or silicate scale formations. The method will control silica scale formation in treated systems with silica residuals exceeding those permitted by prior art (maximum solubility 125 to 180 mg/l monomeric silica), with reduction of source water multivalent metal ions (hardness) to specified residuals and pH control at 9.0 or higher. The higher residuals of soluble silica and higher pH levels maintained via the present methods of the present inventions provide highly effective polarization (corrosion barrier formation) and exceptional corrosion protection for carbon steel, copper, copper alloy and stainless steel metals (less than 0.3 mpy for mild steel, and less than 0.1 mpy copper, copper alloy, and stainless steel). Moderately higher corrosion rates may be acceptable to end users when low silica source waters do not permit attainment of residuals approaching or exceeding 200 mg/l SiO2 in the method treated water at the system's maximum attainable source water concentrations. Such moderately elevated corrosion levels are superior or equivalent to current art. Comparable corrosion rates for carbon steel in aqueous systems with existing methods of the present inventions are optimally in the range of 2 to 5 mpy. When pH is increased to levels higher than 9.0, and residuals of silica are increased, approaching 200 mg/l SiO2, corrosion levels will be reduced to those levels disclosed in Applicants' co-pending patent application (Ser. No. not yet assigned), the teachings of which are incorporated herein by reference. Maximum attainable source water concentrations may be limited by low evaporative load and/or uncontrollable system water losses (such as tower drift). If the end user does require lower corrosion rates, such results are attainable by supplemental addition of adjunct silica to the cooling water to provide residuals approaching or greater than 200 mg/L SiO2. Though not fully understood, several corrosion inhibition mechanisms are believed to be contributing to the metals corrosion protection provided by the methods of the present invention, and the synergy of both anodic and cathodic inhibition functions may contribute to the corrosion inhibition process. Control at lower silica residuals probably reduces the effectiveness of corrosion inhibition due to reduction of available monomeric silica and converted multimeric forms of silica that provide anodic corrosion inhibition to metals with the method. Higher concentrations of silica and higher pH levels will provide increased multimeric silica residual concentrations for optimum anodic protection afforded by the method. Operating at lower soluble silica concentrations will also reduce the corrosion inhibition effectiveness of method treated systems if pretreatment upsets lead to elevated hardness levels in the source water exceeding those specified in the method, since high source water residuals of hardness salts can then more easily absorb and deplete the reduced multimeric silica residuals formed by the method at low silica residual conditions. In this regard, an anodic corrosion inhibitor mechanism results from increased residuals of soluble silica provided by the present methods, particularly in the multimeric form. Silicates inhibit aqueous corrosion by hydrolyzing to form negatively charged colloidal particles. These particles migrate to anodic sites and precipitate on the metal surfaces where they react with metallic ion corrosion products. The result is the formation of a self-repairing gel whose growth is self-limited through inhibition of further corrosion at the metal surface. Unlike the monomeric silica form normally found in source water that fails to provide effective corrosion inhibition, the methods of the present invention provide such beneficial effect by relying upon the presence and on control of total soluble silica residuals, with conversion of natural monomeric silica to the multimeric forms of silica at much higher levels, through application of the combined control ranges as set forth above. In this respect, the removal of most source water calcium and magnesium ions is operative to prevent reaction and adsorption of the multimeric silica forms on the metal oxide or metal salt precipitates from source water, which is believed to be an important contribution to the effectiveness of this corrosion inhibition mechanism afforded by the present invention. The resultant effective formation and control of the multimeric silica residuals with such methods of the present invention has not heretofore been available. In addition to an anodic corrosion inhibition mechanism, a cathodic inhibition mechanism is also believed to be present. Such inhibition is caused by an increased hydroxyl ion concentration provided with the higher pH control range utilized in the practice of the present invention. In this regard, iron and steel are generally considered passive to corrosion in the pH range of 10 to 12. The elevated residual of hydroxyl ions supports equilibrium with hydroxyl ion produced during oxygen reduction at the cathode, and increases hydroxyl ion availability to react with iron to form ferrous hydroxide. As a consequence, ferrous hydroxide precipitates form at the metal surface due to very low solubility. The ferrous hydroxide will further oxidize to ferric oxide, but these iron reaction products remain insoluble at the higher pH levels attained by implementing the methods described herein to polarize or form a barrier that limits further corrosion. At the 9 to 10 pH range (as utilized in the practice of the present invention), effective hydroxyl ion passivation of metal surfaces may be aided by the pretreatment reduction of hardness ions (calcium and magnesium) in the source water that may compete with this reaction and interfere with metal surface barrier formation. Galvanized steel and aluminum may be protected in general by the silicate corrosion inhibitor mechanism discussed herein, but protective films may be destabilized at water-air-metal interfaces. Steel, copper, copper alloy, stainless steel, fiberglass, and plastic are thus ideal aqueous system materials for application of the methods of the present inventions of the present invention. The extensive improvement in corrosion protection provided by the methods of the present invention is not normally attainable with prior art methods when they utilize significantly higher residuals of aggressive ions (e.g., chloride and sulfate) and the accompanying greater ionic or electrolytic strength present in the aqueous system water. This may result from either use of acid for scale control and/or concentration of source water ions in the aqueous system. As is known, corrosion rates generally increase proportionately with increasing ionic strength. Accordingly, through the ability to protect system metals exposed to this increased electrolytic corrosion potential, opportunity for water conservation and environmental benefits that result with elimination of system discharge used with previous methods to reduce corrosion or scaling problems in aqueous systems can be readily realized through the practice of the methods disclosed herein. Indeed, significant water conservation can still be obtained with the method, even operating with silica residuals less than 200 mg/L, through elimination of blowdown wastage and subsequent concentration of source water dissolved solids (conductivity) to higher levels, without silicate scale formation or excessive corrosion. Still further, the methods of the present inventions of the present invention can advantageously provide gradual removal of hardness scale deposits from metal surfaces. This benefit is accomplished through both pretreatment removal of the majority of the scale forming (hardness) metal ions and control of system water at the specified higher ionic strength control ranges. Solubility of hardness salts is increased by the higher ionic strength (conductivity) provided by the present methods of the present invention, which has been determined with high solids water such as seawater, and may contribute to the increased solubility of deposits present within the aqueous environment so treated. Studies conducted with hardness scale coated metal coupons in treated systems demonstrated a significant deposit removal rate for CaCO3 scale films in ten days. Control of source water hardness at lower specified residuals will probably be required to achieve optimum rate of hardness scale removal. Furthermore, the present methods advantageously prohibits microorganism propagation due to the higher pH and dissolved solids levels that are attained. Biological fouling potentials are thus significantly reduced. In this regard, the methods of the present inventions disclosed herein create a chemical environment that inhibits many microbiological species that propagate at the pH and dissolved solids chemistry ranges used with previous treatment approaches. The reduction in aqueous system discharge as further provided as a by product of the present invention also permits use of residual biocides at more effective and economical dosages that impede development of problem concentrations of any microbiological species that are resilient in the aqueous environment generated through the practice of the methods of the present inventions disclosed herein. A still further advantage of the methods of the present invention include the ability of the same to provide a lower freeze temperature in the aqueous system, comparable to ocean water, and avert potential mechanical damage from freezing and/or operational restrictions for systems located in freeze temperature climates. Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts and steps described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices and methods of the present inventions within the spirit and scope of the invention. For example, since the methods of the present invention provides both effective silicate scale control and corrosion inhibition when using high silica or high dissolved solids source waters, extensive variation in source water quality can be tolerated. These source waters might otherwise be unacceptable and uneconomical for use in such aqueous systems. In addition, such modifications may include, for example, using other conventional water treatment chemicals along with the methods of the present invention, and could include other scale inhibitors, such as for example phosphonates, to control scales other than silica, corrosion inhibitors, biocides, dispersants, defoamers and the like. As will be appreciated, however, control at lower conductivity levels may reduce the effectiveness of the method in removing existing hardness deposits, lowering of system water freeze temperature, and prohibition of microorganism propagation. Accordingly, the present invention should be construed as broadly as possible. As an illustration, below there are provided non-restrictive examples of an aqueous water system that has been treated with methods conforming to the present invention. EXAMPLES OF SILICATE SCALE INHIBITOR METHOD The following analytical tests were performed on a cooling tower system treated with the methods of the present invention to demonstrate the efficacy of the present invention for controlling the solubility of silica and silicate species, and preventing scale deposition of these species. Two samples of each of the following: 1) varying source water; 2) the resultant treated system water; and 3) tower sump insoluble accumulations, for a total of six samples were analyzed from different operating time frames. Although the exact mechanism of action of the process is not completely understood, the methods of the present invention minimize the turbidity of the treated water, which is considered a demonstration of an effective silica and silicate scale inhibitor. Methods that produce treated water of less than eight nephelometric turbidity units (NTU) are considered improvements over the current available technology. Turbidity measurements (Table 1) performed on samples taken from the cooling systems, before and after filtration through a 0.45-micron filter, illustrate effective silicate inhibition in the treated water. The turbidity levels are well below typical cooling tower systems, in particular at such high concentrations (80 COC), and indicate the methods of the present invention provide controlled non-adherent precipitation of excess silica and other insoluble materials entering the system. Clean heat exchanger surfaces have confirmed that the method silica precipitation is non-adherent. The precipitated silica forms are contained in the cooling tower sump. However, the volume of precipitant and scrubbed accumulations in the tower sump were not appreciably greater than previous treatment methods due to reduction of insoluble multivalent metal salt precipitates by pretreatment removal. TABLE 1 Tower Water Turbidity Analyses Sample No. 1: (Turbidity, NTU) Neat, 4 NTU; Filtered, 2 NTU Sample No. 2: (Turbidity, NTU) Neat, 3 NTU The cooling tower and makeup water analytical tests performed in Table 2 and Table 3 illustrate the effectiveness of the methods of the present invention in maintaining higher levels of soluble silica in the cooling tower system when parameters are controlled within the specified pH and low makeup hardness ranges. Soluble silica residuals are present at 306 and 382 mg/L in these tower samples at the respective 9.6 and 10.0 pH levels. The lower cycles of concentration (COC) for silica in these tower samples, as compared to the higher cycled residuals for soluble chemistries (chloride, alkalinity, conductivity), indicate that excess silica is precipitating as non-adherent material, and accumulating in the tower basin. This is confirmed by the increased ratio of silica forms found in tower basin deposit analyses. System metal and heat exchange surfaces were free of silica or other scale deposits. TABLE 2 Cooling Tower Sample No. 1/Makeup/Residual Ratios (COC) Makeup SAMPLE/TESTS Tower (soft) COC Conductivity, 33,950 412 82.4 μmhos (Un-neutralized) pH 10.01 8.23 NA Turbidity, NTUs Neat 3 0.08 NA Filtered (0.45μ) — — — Copper, mg/L Cu ND ND NA Zinc, mg/L ND ND NA Silica, mg/L SiO2 382 9.5 40.2 Calcium, mg/L 16.0 0.20 NA CaCO3 Magnesium, mg/L 3.33 0.05 NA CaCO3 Iron, mg/L Fe ND ND NA Aluminum, mg/L Al ND ND NA Phosphate, mg/L ND ND NA PO4 Chloride, mg/L 6040 80 75.5 Tot. Alkalinity, 13200 156 84.6 mg/L ND = Not Detectable; NA = Not Applicable; COC = Cycles of Concentration TABLE 3 Cooling Tower Sample No. 2/Makeup/Residual Ratios (COC) Makeup SAMPLE/TESTS Tower (soft) COC Conductivity, 66,700 829 80 μmhos (Un-neutralized) pH 9.61 7.5 NA Turbidity, NTUs Neat 4 0.08 NA Filtered (0.45μ) 2 — — Zinc, mg/L ND ND NA Silica, mg/L SiO2 306.4 11 28 Calcium, mg/L 21.5 0.20 NA CaCO3 Magnesium, mg/L 0.65 0.05 NA CaCO3 Iron, mg/L Fe ND ND NA Aluminum, mg/L Al ND ND NA Phosphate, mg/L ND ND NA PO4 ND = Not Detectable; NA = Not Applicable; COC = Cycles of Concentration Microscopic and chemical analysis of deposit samples from accumulated residue in the tower basin of a system treated by present methodology are shown in Exhibit 1 and Exhibit 2. Both analyses illustrate the significant ratio of silica materials in the deposit. The major proportion of this silica is the probable result of silica adsorption or reaction with insoluble precipitates of multivalent metals as they concentrated in the tower water. Visual inspections of heat transfer equipment in the system treated by this method have confirmed that it has remained free of silica and other scale deposits. System heat transfer efficiencies were also maintained at minimum fouling factor levels. Exhibit 1 MICROSCOPICAL ANALYSIS - POLARIZED LIGHT MICROSCOPY DEPOSIT DESIGNATION: Cooling Tower Basin Deposit % ESTIMATED CONSTITUENTS >30 Amorphous silica, including assorted diatoms, probably including amorphous magnesium silicate; calcium carbonate (calcite) 1-2 Assorted clay material including feldspar; hydrated iron oxide; carbonaceous material <1 Silicon dioxide (quartz); assorted plant fibers; unidentified material including possibly aluminum oxide (corundum) Exhibit 2 CHEMICAL ANALYSIS - DRIED SAMPLE DEPOSIT DESIGNATION: Cooling Tower Basin Deposit % ESTIMATED CONSTITUENTS 12.1 CaO 8.5 MgO 5.2 Fe3O4 3.7 Fe2O3 <0.5 Al2O3 13.2 Carbonate, CO2 51.1 SiO2 5.7 Loss on Ignition Most probable combinations: Silica ˜54%, Calcium Carbonate ˜32%, Oxides of Iron ˜9%, Mg and Al Oxides ˜5%. EXAMPLES OF CORROSION INHIBITION METHODS OF THE PRESENT INVENTION The data in Table 4 illustrate the effectiveness of the methods of the present invention in inhibiting corrosion for carbon steel and copper metals evaluated by weight loss coupons in the system. No pitting was observed on coupon surfaces. Equipment inspections and exchanger tube surface testing have confirmed excellent corrosion protection. Comparable corrosion rates for carbon steel in this water quality with existing methods of the present inventions are optimally in the range of 2 to 5 mpy. TABLE 4 CORROSION TEST DATA Specimen Type Carbon Steel Copper Test location Tower Loop Tower loop Exposure period 62 Days 62 Days Corrosion Rate (mpy) 0.3 <0.1 EXAMPLES OF SCALE DEPOSIT REMOVAL The data in Table 5 illustrate harness (CaCO3) scale removal from metal surfaces in a tower system treated with the methods of the present invention through coupon weight loss reduction. Standard metal coupons that were scaled with CaCO3 film were weighed before and after ten days of exposure and the visible removal of most of the scale thickness. The demonstrated CaCO3 weight loss rate will provide gradual removal of hardness scale deposits that have occurred in a system prior to method treatment. TABLE 5 SCALE DEPOSIT REMOVAL TEST DATA Specimen Type Carbon Steel Copper Test location Tower Loop Tower loop Exposure period 10 Days 10 Days Scale Removal (mpy) 8.3 8.1 | <SOH> BACKGROUND OF THE INVENTION <EOH>Silica is one of the major scale and fouling problems in many processes using water. Silica is difficult to deal with because it can assume many low solubility chemical forms depending on the water chemistry and metal surface temperature conditions. Below about pH 9.0, monomeric silica has limited solubility (125-180 mg/L as SiO 2 ) and tends to polymerize as these concentrations are exceeded to form insoluble (amorphous) oligomeric or colloidal silica. At higher pH, particularly above about pH 9.0, silica is soluble at increased concentrations of the monomeric silicate ion or in the multimeric forms of silica. Since conversion can be slow, all of these forms may exist at any one time. The silicate ion can react with polyvalent cations like magnesium and calcium commonly present in process waters to produce salts with very limited solubility. Thus it is common for a mixture of many forms to be present: monomeric, oligomeric and colloidal silica; magnesium silicate, calcium silicate and other silicate salts. In describing this complex system, it is common practice to refer to the mixture merely as silica or as silica and silicate. Herein these terms are used interchangeably. To address such problem, methods for controlling deposition and fouling of silica or silicate salts on surfaces in a aqueous process have been derived and include: 1) inhibiting precipitation of the material from the process water; 2) dispersing precipitated material after it has formed in the bulk water; 3) maintaining an aqueous chemical environment that supports formation of increased residuals of soluble silica species; and 4) producing a non-adherent form of silica precipitants in the bulk water. The exact mechanism by which specific scale inhibition methods of the present inventions function is not well understood. In industrial application, most scale and corrosion control methods used in aqueous systems typically rely on the addition of a scale and corrosion inhibitor in combination with controlled wastage of system water to prevent scale and corrosion problems. In this regard, the major scale formation potentials are contributed by the quantity of hardness (calcium and magnesium) and silica ions contributed by the source water, while the major corrosive potential results from the ionic or electrolytic strength in the system water. Treatment methods to minimize corrosion have further generally relied on the addition of chemical additives that inhibit corrosion through suppression of corrosive reactions occurring at either the anode or the cathode present on the metal surface, or combinations of chemical additives that inhibit reactions at both the anode and cathode. The most commonly applied anodic inhibitors include chromate, molybdate, orthophosphate, nitrite and silicate whereas the most commonly applied cathodic inhibitors include polyphosphate, zinc, organic phosphates and calcium carbonate. In view of toxicity and environmental concerns, the use of highly effective heavy metal corrosion inhibitors, such as chromate, have been strictly prohibited and most methods now rely on a balance of the scale formation and corrosive tendencies of the system water and are referred to in the art as alkaline treatment approaches. This balance, as applied in such treatment approaches, is defined by control of system water chemistry with indices such as LSI or Ryznar, and is used in conjunction with combinations of scale and corrosion inhibitor additives to inhibit scale formation and optimize corrosion protection at maximum concentration of dissolved solids in the source water. These methods, however, are still limited by the maximum concentration of silica and potential for silicate scale formation. Moreover, corrosion rates are also significantly higher than those available with use of heavy metals such as chromate. Along these lines, since the use of chromate and other toxic heavy metals has been restricted, as discussed above, corrosion protection has generally been limited to optimum ranges of 2 to 5 mils per year (mpy) for carbon steel when treating typical source water qualities with current corrosion control methods. Source waters that are high in dissolved solids or are naturally soft are even more difficult to treat, and typically have even higher corrosion rates. In an alternative approach, a significant number of methods of the present inventions for controlling scale rely on addition of acid to treated systems to control pH and reduce scaling potentials at higher concentrations of source water chemistry. Such method allows for conservation of water through modification of the concentrated source water, while maintaining balance of the scale formation and corrosive tendencies of the water. Despite such advantages, these methods have the drawback of being prone to greater risk of scale and/or corrosion consequences with excursions with the acid/pH control system. Moreover, there is an overall increase in corrosion potential due to the higher ionic or electrolytic strength of the water that results from addition of acid ions that are concentrated along with ions in the source water. Lower pH corrosion control methods further rely on significantly higher chemical additive residuals to offset corrosive tendencies, but are limited in effectiveness without the use of heavy metals. Silica concentration must still be controlled at maximum residuals by system water wastage to avoid potential silica scaling. In a further approach, source water is pretreated to remove hardness ions in a small proportion of systems to control calcium and magnesium scale potentials. These applications, however, have still relied on control of silica residuals at previous maximum guideline levels through water wastage to prevent silica scale deposits. Corrosion protection is also less effective with softened water due to elimination of the balance of scale and corrosion tendency provided by the natural hardness in the source water. Accordingly, there is a substantial need in the art for methods that are efficiently operative to inhibit corrosion and scale formation that do not rely upon the use of heavy metals, extensive acidification and/or water wastage that are known and practiced in the prior art. There is additionally a need in the art for such processes that, in addition to being efficient, are extremely cost-effective and environmentally safe. Exemplary of those processes that would likely benefit from such methods would include cooling water processes, cooling tower systems, evaporative coolers, cooling lakes or ponds, and closed or secondary cooling and heating loops. In each of these processes, heat is transferred to or from the water. In evaporative cooling water processes, heat is added to the water and evaporation of some of the water takes place. As the water is evaporated, the silica (or silicates) will concentrate and if the silica concentration exceeds its solubility, it can deposit to form either a vitreous coating or an adherent scale that can normally be removed only by laborious mechanical or chemical cleaning. Along these lines, at some point in the above processes, heat is extracted from the water, making any dissolved silicate less soluble and thus further likely to deposit on surfaces, thus requiring removal. Accordingly, a method for preventing fouling of surfaces with silica or silicates, that further allows the use of higher levels of silica/silicates for corrosion control would be exceptionally advantageous. In this respect for cooling water, an inhibition method has long been sought after that would enable silica to be used as a non-toxic and environmentally friendly corrosion inhibitor. To address these specific concerns, the current practice in these particular processes is to limit the silica or silicate concentration in the water so that deposition from these compounds does not occur. For example in cooling water, the accepted practice is to limit the amount of silica or silicates to about 150 mg/L, expressed as SiO 2 . Reportedly, the best technology currently available for control of silica or silicates in cooling water is either various low molecular weight polymers, various organic phosphate chemistries, and combinations thereof. Even with use of these chemical additives, however, silica is still limited to 180 mg/L in most system applications. Because in many arid areas of the U.S. and other parts of the world make-up water may contain from 50-90 mg/L silica, cooling water can only be concentrated 2 to 3 times such levels before the risk of silica or silicate deposition becomes too great. A method that would enable greater re-use or cycling of this silica-limited cooling water would be a great benefit to these areas. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention specifically addresses and alleviates the above-identified deficiencies in the art. In this regard, the invention relates to methods for controlling silica and silicate fouling problems, as well as corrosion of system metallurgy (i.e. metal substrates) in aqueous systems with high concentrations of dissolved solids. More particularly, the invention is directed to the removal of hardness ions from the source water and control of specified chemistry residuals in the aqueous system to inhibit deposition of magnesium silicate and other silicate and silica scales on system surfaces, and to inhibit corrosion of system metallurgy. To that end, we have unexpectedly discovered that the difficult silica and silicate scaling problems that occur in aqueous systems when silica residuals exceed 125 mg/L, and more preferably are approaching or greater than 200 mg/L as SiO 2 , to as high as 4000 mg/L of silica accumulation (cycled accumulation from source water), can be controlled by initially removing hardness ions (calcium and magnesium) from the makeup source water (i.e., water fed to the aqueous system) using pretreatment methods of the present inventions known in the art, such as through the use of ion exchange resins, selective ion removal with reverse osmosis, reverse osmosis, electrochemical removal, chemical precipitation, or evaporation/distillation. Preferably, the pretreatment methods of the present invention will maintain the total hardness in the makeup water at less than 20% of the makeup silica residual (mg/L SiO 2 ), as determined from an initial assessment of the source water. In some embodiments, the total hardness ions will be maintained at less than 5% of the makeup silica residual. When source makeup water is naturally soft, with less than 10 mg/L hardness as CaCO 3 , pretreatment removal of hardness ions may be bypassed in some systems. Thereafter, the conductivity (non-neutralized) in the aqueous system is controlled such that the same is maintained at some measurable level (i.e., at least 1 μmhos and the pH of the source water elevated to a pH of approximately 9.0, and preferably 9.6, or higher. With respect to the latter, the pH may be adjusted by the addition of an alkaline agent, such as sodium hydroxide, or by simply removing a portion of the aqueous system water through such well known techniques or processes as evaporation and/or distillation. In a related application, we have unexpectedly discovered that the excessive corrosion of carbon steel, copper, copper alloys, and stainless steel alloys in aqueous systems due to high ionic strength (electrolytic potential) contributed by dissolved solids source water or highly cycled systems can likewise be controlled by the methods of the present inventions of the present invention. In such context, the methods of the present invention comprises removing hardness ions (calcium and magnesium) from the makeup source water using known pretreatment methods of the present inventions, such as ion exchange resins, selective ion removal with reverse osmosis, reverse osmosis, electrochemical removal, chemical precipitation, or evaporation/distillation. The pretreatment methods of the present invention will preferably maintain the total hardness ratio in the makeup water at less than 20%, and preferably at least less than 5%, of the makeup silica residual (mg/L SiO 2 ), as determined from an initial analysis of the source water. When source makeup water is naturally soft, with less than 10 mg/L hardness as CaCO 3 , pretreatment removal of hardness ions may be bypassed in some systems. Thereafter, the conductivity (non-neutralized) in the aqueous system is controlled such that the same is maintained at some measurable level (i.e., at least 1 μmhos). Alkalinity is then controlled as quantified by pH at 9.0 or higher, with a pH of 9.6 being more highly desired in some applications along with control of soluble silica at residual concentrations approaching or exceeding 200 mg/L, but not less than 10 mg/L, with control at more highly desired residuals in some applications approaching or exceeding 300 mg/L as SiO 2 . With respect to the latter, the SiO 2 may be adjusted by the addition of a silica/silicate agent, such as sodium silicate, or by simply removing a portion of the aqueous system water through such well known techniques or processes as evaporation and/or distillation. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20050927 | 20050714 | 63101.0 | 1 | HRUSKOCI, PETER A | COOLING WATER SCALE AND CORROSION INHIBITION | SMALL | 1 | CONT-ACCEPTED | 2,004 |
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10,814,375 | ACCEPTED | Integrated circuit with metal layer having carbon nanotubes and methods of making same | A method of fabricating an integrated circuit comprises forming or providing a solution containing carbon nanotubes and forming a metal layer utilizing the solution. | 1. A method of fabricating an integrated circuit comprising: forming or providing a solution containing carbon nanotubes; and forming a metal layer utilizing the solution. 2. The method of claim 1 wherein the solution containing carbon nanotubes comprises: carbon nanotube suspensions; and metal ions. 3. The method of claim 2 wherein the carbon nanotube suspensions comprise single wall, arm chair carbon nanotubes. 4. The method of claim 2 wherein the solution containing carbon nanotubes further comprises a support electrolyte. 5. The method of claim 2 wherein the solution containing carbon nanotubes further comprises a reducing agent. 6. The method of claim 5 wherein the reducing agent is a reducing agent selected from the group consisting of hyphophosphite, amino-borane, formaldehyde, glyoxylic acid, hydrazine and redox pairs. 7. The method of claim 6 wherein the redox pairs is a redox pair selected from the group consisting of (Ti3+, Ti2+) and (Fe2+,Fe3+). 8. The method of claim 2 wherein the solution containing carbon nanotubes further comprises a complexing agents. 9. The method of claim 8 wherein the complexing agent is a complexing agent selected from the group consisting of tartrate, citric acid and ethylenediaminetetra-acetic acid. 10. The method of claim 2 wherein the metal ions are metal ions selected from the group consisting of copper, silver, gold, aluminum, tin, indium, nickel, cobalt, iron, cadmium, chromium, ruthenium, rhodium, rhenium, antimony, bismuth, platinum, zinc, palladium, manganese, iridium, osmium, molybdenum, tungsten and alloys of the afore enumerated metals. 11. The method of claim 2 wherein the carbon nanotube suspension comprises: a plurality of single-walled, arm chair carbon nanotubes; and a solvent selected from the group consisting of water, ethanol, methanol and ethyleneglycol. 12. The method of claim 1 wherein said forming of the metal layer comprises electroplating a substrate using the solution. 13. The method of claim 1 wherein said forming of the metal layer comprises electroless of a substrate using the solution. 14. The method of claim 1 wherein said forming of the metal layer comprises electrophoresis of a substrate using the solution. 15. The method of claim 14 further comprising annealing the electrophoresed substrate. 16. The method of claim 1 wherein said forming of the metal layer comprises spinning the solution onto the substrate. 17. The method of claim 16 further comprising annealing the substrate with the spun-on solution. 18. The method of claim 1 further comprising removing excess materials. 19. The method of claim 1 further comprising deposition of a passivation layer on the metal layer. 20. An integrated circuit comprising: a substrate comprising silicon; and one or more metal layers, at least one metal layer comprising copper and carbon nanotubes wherein the at least one metal layer is formed utilizing a solution containing carbon nanotubes. 21. The integrated circuit of claim 20 wherein the solution containing carbon nanotubes is deposited on an oxide layer with dual damascene features. 22. The integrated circuit of claim 20 wherein forming the metal layer comprises electroless plating of a substrate using solution containing carbon nanotubes. 23. The integrated circuit of claim 20 wherein forming the metal layer comprises electroplating of a substrate using solution containing carbon nanotubes. 24. The integrated circuit of claim 20 wherein forming the metal layer comprises electrophoresis of a substrate using solution containing carbon nanotubes. 25. The integrated circuit of claim 20 wherein the forming the metal layer comprises spinning the solution containing carbon nanotubes onto a substrate. 26. A system comprising: a semiconductor component including; a substrate comprising silicon; and one or more metal layers, at least one metal layer comprising copper and carbon nanotubes wherein the at least one metal layer is formed utilizing a solution containing carbon nanotubes.; a networking interface; and at least one bus coupled between the semiconductor component and networking interface to facilitate data exchange between the semiconductor component and networking interface. 27. The system of claim 26 wherein the solution containing carbon nanotubes is deposited on an oxide layer with dual damascene features. 28. The system of claim 26 wherein forming the metal layer comprises electroplating of a substrate using solution containing carbon nanotubes. 29. The system of claim 26 wherein the semiconductor component is a component selected from the group consisting of a processor and a memory. 30. The system of claim 26 wherein the system is a system selected from a group consisting of a mobile phone, a digital camera, a set-top box, a CD player, and a DVD player. | FIELD OF THE INVENTION The present invention relates in general to the field of integrated circuits and, in particular, to their fabrication. BACKGROUND OF INVENTION Metal layers in integrate circuits are utilized to electrically interconnect various devices fabricated on a substrate. Resistance of the materials utilized in the metal layers affect the speed with which signals can propagate between these devices. To improve the propagation of signals, copper has taken over as the primary metal in use in high speed design applications. Nevertheless, even with increase conductivity of copper, vis-á-vis aluminum, speed issues with copper interconnect exist. For example, as copper conductor features continue to decrease in size, the conductivity resistance associated with the copper conductors increases causing a decrease in speed of signals on these size decreased signal traces. Another problem that affects the propagation of signals is an increase in the electromigration resistance. As conductor feature sizes continue to decrease copper electromigration resistance is limited by such things as surface diffusion and voids. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the present invention will be described referencing the accompanying drawings in which like references denote similar elements, and in which: FIG. 1 illustrates a cross sectional view of a portion of an integrated circuit having a dial damascene features. FIG. 2 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with one embodiment. FIG. 3 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. FIG. 4 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with yet another embodiment. FIG. 5 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. FIG. 6 illustrates is a block diagram of a system including a component formed employing one of the processes of FIG. 2-5, in accordance with one embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS Various aspects of illustrative embodiments of the invention will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments. The phrase “in one embodiment” is used repeatedly. The phrase generally does not refer to the same embodiment; however, it may. The terms “comprising”, “having” and “including” are synonymous, unless the context dictates otherwise. Carbon nanotubes, depending on their configuration, may exhibit various electrical properties. For example, in one configuration, carbon nanotubes may act as semiconductors. In another configuration, carbon nanotubes act as conductors. Specifically, single wall carbon nanotubes in an arm chair configuration exhibit a number of metallic characteristics. Among these metallic characteristics, a number of properties are of particular interest with respect to their possible use as part of a metal layer. Single wall, arm chair carbon nanotubes have been shown to have high electrical and thermal conductivity, e.g. higher than copper. Composite single wall carbon nanotube and copper material have also been shown to have higher electrical conductivity than copper. In addition, single wall carbon nanotubes have high electromigration resistance. Composite single wall carbon nanotube and copper materials have also been shown to have higher electromigration resistance than copper. Disclosed herein are methods of fabricating integrated circuit having conduction layer with potentially higher electrical and thermal conductivity and/or higher electromigration resistance than the prior art. These methods include electro- and electroless plating of metals, electrophoresis and spin on. While the discussion below is focused around the metallization in a dual damascene process, it will be appreciated that the disclosed method can be utilized to provide conductive material application in other integrated circuit processes. FIG. 1 illustrates a cross sectional view of a portion of an integrated circuit having a dual damascene feature, in accordance with one embodiment. The integrated circuit includes a substrate 110. Active components of a circuit are formed on substrate 110. Further, one or more layers of metal are formed to provide for interconnect between the active components. An oxide layer 120 is fabricated on an etch stop layer 125. The oxide layer 120 comprises two layers; one used as a via layer 130 and one as a trench layer 140. One of several methods may be utilized to create the trenches 145 and vias 135. In the via-first method, both layers 130 140 may be etched creating vias 135. Next, the trench layer 140 only may be etched creating trenches 145 for the layer of interconnect. A barrier layer 150 may be placed on the oxide to separate the metallization layer from the oxide layer to prevent interaction between the two layers. A seed layer 160 is then placed on the barrier layer 150. A metal layer 170 is then placed on the seed layer 160. As discussed in more detail below, the metal layer 170 comprises carbon nanotubes. For each of the above processes, a chemical mechanical process may be utilized to planarize the surface of the particular layer. FIG. 2 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with one embodiment. Illustrated is a method for forming an interconnect utilizing co-electroplating to form a metal layer with carbon nanotubes. As illustrated, a substrate with active components is first formed 210. Next, deposition of a dielectric layer, to facilitate formation of interconnects to interconnect the active components, is performed. Further, formation of dual damascene features in the dielectric layer, by using e.g. operations of lithography and etching, is performed 220. Next, a barrier layer and a seed layer are deposited 230. The barrier layer may comprise a material such as tantalum, tantalum nitride, tantalum silicon nitride, titanium nitride, titanium silicon nitride, tungsten nitride, tungsten silicon nitride, cobalt tungsten phosphide or other materials of the like. The barrier layer may be deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or plating. In various embodiments, the seed layer is deposited on the barrier layer. This seed layer may comprise a material such as copper or its alloys. Examples of these include CuAl, CuSn, Culn, CuCd or other materials of the like. The seed layer may be deposited utilizing PVD, CVD or plating. Next, metals containing carbon nanotubes are electroplated to the seed layer 240. In various embodiments, the carbon nanotubes are single wall, arm chair carbon nanotubes, and the electroplating process is a Co-electroplating process. In various embodiments, the electroplating is performed utilizing solutions containing metal ions such as Cu, Ag, Au, Al, Sn, In, Ni, Co, Fe, Cd, Cr, Ru, Rh, Re, Sb, Bi, Pt, Zn, Pd, Mn, Ir, Os, Mo, W, their alloys or other materials of the like. The solution may also contain one or more support electrolyte such as sulfuric acid, sulfonic acid, potassium hydroxide and the like. In particular, the solution further contains (single wall, arm chair) carbon nanotubes suspensions. Carbon nanotubes may be suspended in solvents such as water, ethanol, methanol, ethyleneglycol, and so forth. Suspension can be effectuated by e.g. sonication. Carbon nanotubes can be also made soluble by their functionalization. For example, the carbon nanotubes may be treated with H2SO4 or HNO3 to create a COOH functional group. This may be followed by treatment with S(O)Cl2/H2N—R—SH to create a C(O)N(H)—R—SH functional group. This may be further treated with a reducing agent such as H2PtCl6 to create carbon nanotubes covered with platinum particles. In an alternative embodiment, the solution additionally comprises complexing agents such as ethylenediaminetetra-acetic acid (EDTA), tartrate, citric acid or other materials of the like. Suitable (single wall, arm chair) carbon nanotube suspensions include, but are not limited to, those available from various vendors such as Carbon Nanotechnologies Inc., of Houston Tex. After the metal layer is fabricated, chemical mechanical polish (CMP) or electropolish may be utilized to remove excess materials 250. Further, a passivation or stop etch layer may be optionally deposited on top of the metallization layer 260. In one embodiment, the passivation/etch stop layer may comprise SiN, SiC, electroless cobalt, or other materials of the like. As needed, the procedures 220-260 may be repeated to add additional interconnects. FIG. 3 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. Illustrated is a method for forming an interconnect utilizing electroless plating to deposit a metal layer with carbon nanotubes. As previously, a substrate with active components is formed 310. The substrate may then be planerized utilized CMP. Then, deposition of a dielectric layer to facilitate formation of interconnects to interconnect the active components may be performed. Further, dual damascene features may be formed in the dielectric layer by using e.g. operations of lithography and etching 320. As with the previous embodiment, barrier and seed layers may then be deposited 330. The barrier layer may comprise a material such as tantalum, tantalum nitride, tantalum silicon nitride, titanium nitride, titanium silicon nitride, tungsten nitride, tungsten silicon nitride, cobalt tungsten phosphide, or other materials of the like. The barrier layer may be deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or plating. The seed layer is deposited on the barrier layer. The seed layer may comprise a material made of catalytic material for electroless deposition. Examples of these include copper, cobalt, nickel, gold, platinum, rhodium, ruthenium, silver, palladium, iron, and the like. The seed layer may be deposited utilizing PVD, CVD or plating. Metals containing carbon nanotubes are electrolessly plated to the seed layer to produce an interconnect layer 340. In various embodiments, the carbon nanotubes comprise single wall, arm chair carbon nanotubes, and the electroless plating process comprises a co-electroless plating process. The electroless plating is performed utilizing solutions containing metal ions such as Cu, Ag, Au, Al, Sn, In, Ni, Co, Fe, Cd, Cr, Ru, Rh, Re, Sb, Bi, Pt, Zn, Pd, Mn, Ir, Os, Mo, W, their alloys and the like. The solution may also contain reducing agents, complexing agents and carbon nanotubes suspensions. As discussed previously, various techniques may be utilized to produce the carbon nanotubes suspensions. Reducing agents may comprise compounds such as hyphophosphite, amino-borane, formaldehyde, glyoxylic acid, hydrazine, redox pairs such as Ti3+/Ti4+, Fe2+/Fe3+, or other materials of the like. Complexing agents may comprise compounds such as EDTA, tartrate, citric acid, or other materials of the like. As previously stated, after the metal layer has been laid down, chemical mechanical polish (CMP) or electropolish may be utilized to remove excess materials 350. Deposition of a passivation/etch stop layer may be optionally made on top of the metal layer 360. The passivation/etch stop layer may comprise SiN, SiC, electroless cobalt, or other materials of the like. As needed, the procedures discussed above may be repeated to add additional interconnects. FIG. 4 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with yet another embodiment. Illustrated is a method for forming an interconnect utilizing electrophoresis to deposit a metal layer with carbon nanotubes. As with the previous embodiments, a substrate with active components is formed 410. Deposition of a dielectric layer to facilitate formation of interconnects to interconnect the active components is performed. Further, dual damascene features are formed in the dielectric layer by using e.g. operations of lithography and etching 420. As with the previous embodiments, a barrier layer and seed layer are deposited 430. The barrier layer may comprise a material such as tantalum, tantalum nitride, tantalum silicon nitride, titanium nitride, titanium silicon nitride, tungsten nitride, tungsten silicon nitride, cobalt tungsten phosphide or other materials of the like. The barrier layer may be deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or plating. The seed layer is deposited on the barrier layer. Examples of seed materials include copper, cobalt, nickel, gold, platinum, rhodium, ruthenium, silver, palladium, iron and the like. The seed layer may be deposited utilizing PVD, CVD or plating. Next, electrophoresis of metal particles utilizing solutions comprising metals particles such as Cu, Ag, Au, Al, Sn, In, Ni, Co, Fe, Cd, Cr, Ru, Rh, Re, Sb, Bi, Pt, Zn, Pd, Mn, Ir, Os, Mo, W, their allows or other materials of the like, including carbon nanotubes, is performed 440. In various embodiments, the metal particles are 10 to 50 nanometers. In various embodiments, carbon nanotubes are single wall, arm chair carbon nanotubes. The solution may also comprise ligands making the metal particles and the carbon nanotubes charged. The solution may further comprise support electrolyte such as H2O, ethyleneglycol or other materials of the like. An example of such suitable solutions include, but are not limited to, those provided by ALD Nanosolutions, Inc. After the electrophoresis of the metal particles containing carbon nanotubes, an annealing process may be applied 450. This process is performed to melt the metal particles containing the carbon nanotubes. The process may be performed at a range of temperatures (e.g. 200 to 500 degree C.) for a period from 1 to 200 minutes. As with the previous embodiments, a CMP or electropolish may be performed to remove excess material 460. A passiviation/etch stop layer may optionally be deposited on top of the metal layer 470. The above process may be repeated for additional interconnects. FIG. 5 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. Illustrated is a method for forming an interconnect, utilizing spin-on to deposit a metal layer with carbon nanotubes. As with the previous embodiments, a substrate with active components is formed 510. Deposition of a dielectric layer to facilitate formation of interconnects to interconnect the active components may be performed. Further, dual damascene features are formed in the dielectric layer by using e.g. operations of lithography and etching 520. As with the previous embodiments, a barrier layer and a seed layer are deposited 530. The barrier layer may comprise a material such as tantalum, tantalum nitride, tantalum silicon nitride, titanium nitride, titanium silicon nitride, tungsten nitride, tungsten silicon nitride, cobalt tungsten phosphide or other materials of the like. The barrier layer may be deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or plating. Similarly, as with several previous embodiments, the seed layer is deposited on the barrier layer. The seed layer may comprise a material made of catalytic material for electroless deposition. Examples of these include copper, cobalt, nickel, gold, platinum, rhodium, ruthenium, silver, palladium, iron and the like. The seed layer may be deposited utilizing PVD, CVD or plating. Spin on of metal particles utilizing solutions comprising metals particles such as Cu, Ag, Au, Al, Sn, In, Ni, Co, Fe, Cd, Cr, Ru, Rh, Re, Sb, Bi, Pt, Zn, Pd, Mn, Ir, Os, Mo, W, their alloys or other materials of the like, including carbon nanotubes, is performed 540. In various embodiments, the metal particles are 10 to 50 nanometers in size. In various embodiments, the carbon nanotubes are single wall, arm chair carbon nanotubes. In various embodiments, spin on may be performed at substrate rotation speed of about 20-100 rpm for about 1-5 min at room temperature. An example of such suitable solutions include, but are not limited to, those provided by NSI Corp. The solution may also comprise ligands and carbon nanotubes charged. The solution may further comprise support electrolyte such as H2O, ethyleneglycol or other materials of the like. After the spin-on of the metal particles containing carbon nanotubes, an annealing process may be applied 550. This process is performed to melt the metal particles containing the carbon nanotubes. The process may be performed at a range of temperatures (e.g. 200 to 500 degree C.) for a period from 1 to 200 minutes. As with the previous embodiments, a CMP or electropolish may be performed to remove excess materials 560. A passiviation/etch stop layer may be optionally deposited on top of the interconnect lines 570. The above process may be repeated for additional interconnects. Discussed above are methods of fabricating materials which has the potential of exhibiting high electrical and thermal conductivity and/or high electromigration resistance. The resulting metal structures containing (single wall, arm chair) carbon nanotubes dispersed therein to contribute to the increase of, among other things, electrical conductivity. FIG. 6 illustrates is a block diagram of a system 600 including at least one component with metal layers containing carbon nanotubes. As shown, the system 600 includes a processor 610 and temporary memory 620, such as SDRAM and DRAM, on high-speed bus 605. High-speed bus is connected through bus bridge 630 to input/output (I/O) bus 615. I/O bus 615 connects permanent memory 640, such as flash devices and fixed disk device, networking interface 660 and I/O devices 650 to each other and bus bridge 630. At least one of the components, e.g. processor 610, temporary memory 620, and so forth, is formed having e.g. interconnect, with metal layers having carbon nanotubes. More over, in various embodiments, the carbon nanotubes are single wall, arm chair, carbon nanotubes. In various embodiments, the metal layers with the carbon nanotubes are formed using one of the earlier described processes. In various embodiments, system 600 may be a hand held computing device, a mobile phone, a digital camera, a tablet computer, a laptop computer, a desktop computer, a set-top box, a CD player, a DVD player, or a server. Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiment shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof. | <SOH> BACKGROUND OF INVENTION <EOH>Metal layers in integrate circuits are utilized to electrically interconnect various devices fabricated on a substrate. Resistance of the materials utilized in the metal layers affect the speed with which signals can propagate between these devices. To improve the propagation of signals, copper has taken over as the primary metal in use in high speed design applications. Nevertheless, even with increase conductivity of copper, vis-á-vis aluminum, speed issues with copper interconnect exist. For example, as copper conductor features continue to decrease in size, the conductivity resistance associated with the copper conductors increases causing a decrease in speed of signals on these size decreased signal traces. Another problem that affects the propagation of signals is an increase in the electromigration resistance. As conductor feature sizes continue to decrease copper electromigration resistance is limited by such things as surface diffusion and voids. | <SOH> BRIEF DESCRIPTION OF DRAWINGS <EOH>Embodiments of the present invention will be described referencing the accompanying drawings in which like references denote similar elements, and in which: FIG. 1 illustrates a cross sectional view of a portion of an integrated circuit having a dial damascene features. FIG. 2 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with one embodiment. FIG. 3 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. FIG. 4 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with yet another embodiment. FIG. 5 shows a flowchart illustrating a method for creating portions of an integrated circuit design, in accordance with another embodiment. FIG. 6 illustrates is a block diagram of a system including a component formed employing one of the processes of FIG. 2-5 , in accordance with one embodiment. detailed-description description="Detailed Description" end="lead"? | 20040330 | 20071127 | 20051006 | 75824.0 | 0 | PAREKH, NITIN | INTEGRATED CIRCUIT WITH METAL LAYER HAVING CARBON NANOTUBES AND METHODS OF MAKING SAME | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,415 | ACCEPTED | Incorporation by reference | A jack includes a base having a pair of spaced apart side members with a substantially horizontally oriented platform overlying a forward portion of the base. A pair of support arms pivotably connect the platform to the side members, and a lift arm is pivotably connected between the platform and the side members. A driver assembly mounted to a rear portion of the base in response to manual actuation moves the platform between a lowered and a plurality elevated positions while maintaining the horizontal orientation of the platform. | 1. A jack comprising a cast metal base having a pair of spaced apart, unitary, rigid, substantially planar side members each with a lower edge, at least a portion of each said lower edge adapted to rest on ground during use of the jack, each side member having a forward segment and a rear segment, the forward segments being separated by a predetermined distance and being substantially parallel, and each forward segment having a front end, a rear end, and a predetermined length, said predetermined length of each forward segment being substantially equal and said front ends being in substantial alignment and said rear ends being in substantial alignment, a substantially horizontally oriented, cast metal platform having a forward end, a rear end, opposed sides, and an upper surface adapted to support a load in an elevated position with the entire load above ground level, said platform having a width that is substantially equal to said predetermined distance and a length that is substantially equal to said predetermined length, a pair of support arms each connected between one side member and the platform, each support arm having one end pivotably connected to the forward end of the platform and another end pivotably connected to an intermediary portion of a forward segment one the side member to which said support arm is connected, a cast metal lift arm having a forward end pivotably connected to the rear end of the platform at a central portion thereof and a rear end pivotably mounted between the rear segments of the side members, and a driver assembly mounted to the base between the rear segments of the side members, said driver assembly including a hydraulic cylinder having ram element coupled to the lift arm, said ram element in response to manual actuation moving substantially horizontal causing the platform to move between a lowered position and a plurality of different elevated positions, said support arms and lift arm moving in unison and substantially parallel to each other so said platform maintains a substantially horizontal orientation as the platform moves between lowered and elevated positions. 2. The jack of claim 1 where said load has a maximum weight of 2500 pounds. 3. The jack of claim 1 including a detachable, elongated safety stop member that is manually detached and, when in an elevated position, is located so that at least a portion thereof engages a top edge of the base if the platform abruptly returns to the lowered position. 4. The jack of claim 1 including an axle that extends between the forward ends of the forward segments, said axle carrying a pair of wheels. 5. The jack of claim 4 where at least one of the wheels lie outboard of one side member. 6. The jack of claim 1 including a wheel attached to the rear segment of each side member, 7. (cancelled) 8. The jack of claim 1 including a detachable handle for actuating the driver assembly. 9. The jack of claim 1 where the base includes cast metal wheel mounts that are detachably connected to the rear segments of the base. 10. The jack of claim 1 where each rear segment includes a cast metal wheel mount that is integral therewith. 11. The jack of claim 1 where said lift arm is coupled to the driver assembly through at least one link connected to the rear end of the lift arm. 13. A jack comprising a pair of spaced apart, cast metal, unitary side members, each side member having a forward segment and a rear segment, the forward segments being substantially parallel and in substantial registration, the rear segments being substantially parallel and in substantial registration, and a substantially horizontally oriented, cast metal, platform that is mounted above the side members to move between a lowered position and a plurality of elevated positions, a pair of support arms, each support arm having one end pivotably connected the platform and an opposed end pivotably connected to one of the forward segments of the side members, and a manually actuated driver assembly connected to a cast metal lift arm that is positioned lengthwise along a longitudinal axis of the jack, said lift arm having one end pivotably connected to the platform and an opposed end pivotably connected between the rear segments of the side members, said lift arm in response to the actuation of the driver assembly moving the platform between lowered and elevated positions, with said platform being maintained by said support arms and said lift arm in a horizontal orientation as said platform moves between lowered and elevated positions. 14. The jack of claim 13 where the platform has a substantially rectangular-shaped configuration. 15. The jack of claim 15 where the platform includes a marginal frame with a hollow interior. 16. The jack of claim 13 where the side members, platform, and lift arm are made from cast aluminum. 17. The jack of claim 13 where the driver assembly includes a fluid reservoir, a pair of caps at opposed side of the reservoir, a hydraulic cylinder having ram element coupled to the lift arm and in communication with the fluid reservoir, said ram element in response to being actuated moving the lift arm so the platform is moved between lowered and elevated positions, one cap being coupled the rear segment of one of the side member and the other cap being coupled the rear segment of the other of the side member. 18. The jack of claim 17 where the one cap fits within an opening in the rear segment of said one side member and the other cap fits within an opening in the rear segment of said other side member. 19. The jack of claim 13 where a brace is attached to each rear segment of each side member. 20. The jack of claim 13 where a first stiffening element extends between front ends of each of said forward segments and a second stiffening element extends between rear ends of each of said forward segments. 21. A jack comprising a pair of spaced apart side members with at least portions of lower edges thereof resting on ground during use of the jack, each side member including a forward segment and a rear segment, the forward and rear segments of the side members being substantially parallel at least one stiffening element extending between the side members, and a substantially horizontally oriented platform having a substantially rectangular-shape with front corners and rear corners, said platform being mounted above the side members to move between a lowered position and a plurality of elevated positions, a pair of support arms each connected between one side member and the platform, one support arm having a first end pivotably connected at or near one front corner of the platform and a second end pivotably connected to the forward segment of one side member and the other support arm having a first end pivotably connected at or near the other front corner of the platform and a second end pivotably connected to the forward segment of the other side member, a manually actuated driver assembly connected to a lift arm that is positioned lengthwise along a longitudinal axis of the jack, said lift arm having one end pivotably connected to the platform between the rear corners and an opposed end pivotably connected between the rear segments of the side members, said lift arm in response to the actuation of the driver assembly moving the platform between lowered and elevated positions, with said platform being maintained by said support arms and said lift arm in a horizontal orientation as said platform moves between lowered and elevated positions. 22. A jack comprising a pair of spaced apart rigid, substantially planar side members with at least portion of lower edges thereof adapted to rest on the ground during use of the jack, each side member having a bend therein to form a forward segment and a rear segment, said forward segments being substantially parallel to each other and said rear ends being substantial parallel to each other, said forward segments separated by a predetermined distance and having predetermined equal lengths, a substantially horizontally oriented platform having a forward end, a rear end, opposed sides, and an upper surface adapted to support a load in an elevate position with the entire load above ground level, said platform having a width that is substantially equal to said predetermined distance and a length that is substantially equal to said predetermined lengths, a pair of support arms each connected between one side member and the platform, each support arm having one end pivotably connected to the forward end of the platform and another end pivotably connected to the forward segment of the side member to which said support arm is connected, a lift arm having a forward end pivotably connected to the rear end of the platform at a central portion thereof and a rear end pivotably mounted between the rear segments of the side members, a driver assembly mounted to the rear segment of the base between the rear segments of the side members, said driver assembly in response to manual actuation moving said support arms and lift arm substantially in parallel so said platform maintains a substantially horizontal orientation as it moves between lowered and elevated positions, 23. A jack comprising a cast aluminum base having a pair of spaced apart, unitary side members, each side member having a forward segment and a rear segment, the forward segments being separated by a predetermined distance at forward ends thereof, said forward segments being substantially parallel and each having a predetermined length, said predetermined lengths being substantially equal, a substantially horizontally oriented, cast aluminum platform having a forward end, a rear end and an upper surface adapted to support a load in an elevated position with the entire load above ground level, said platform having a width that is substantially equal to said predetermined distance and a length that is substantially equal to said predetermined length, a pair of support arms each connected between one side member and the platform, each support arm having one end pivotably connected to the forward end of the platform and another end pivotably connected to the forward segment of the side member to which said support arm is connected, a cast aluminum lift arm having a forward end pivotably connected to the rear end of the platform at a central portion thereof and a rear end having a first section pivotably connected to one side member at the rear segment thereof and a second section pivotably connected to the other side member at the rear segment thereof, a driver assembly mounted to the rear segment of the base between the side members, said driver assembly including a hydraulic cylinder having ram element coupled to the lift member, said ram element in response to manual actuation moving substantially horizontal causing the platform to move between lowered elevated positions. 24. A jack comprising a base having a pair of spaced apart, unitary side members, each side member having a forward segment, an intermediate segment, and a rear segment, said rear segments being separated by a predetermined distance, said forward segments having at least one stiffening element extending between them and a brace member abutting an outer side of each said intermediate segment, a substantially horizontally oriented, platform overlying and being disposed between the side members, a pair of support arms, each support arm having one end pivotably connected to the platform and another end pivotably connected to one of the side members, a unitary lift arm having a forward end pivotably connected to the platform and a rear end pivotably connected between the rear segments, said rear end of the lift arm having a width that is substantially equal to said predetermined distance separating said rear segments, and a driver assembly mounted to the rear segments that upon actuation moves the platform between a lowered position and a plurality of different elevated positions, said platform maintaining a substantially horizontal orientation as said platform moves between lowered and elevated positions. 25. A jack comprising a base having a pair of spaced apart, unitary, side members that are substantially mirror images of each other, each side member having a forward segment, and a rear segment, said forward segments being in substantial registration and defining at least partially a substantially rectangular space having predetermined dimensions, a substantially horizontally oriented, unitary platform having a substantially rectangular shape with dimensions that are slightly less than the dimensions of said rectangular space, a pair of support arms, each support arm having one end pivotably connected to the platform and another end pivotably connected to one of the side members, a unitary lift arm having a forward end pivotably connected to the platform and a rear end pivotably connected to the rear segments of the side members, said lift arm being positioned lengthwise along a longitudinal axis of the jack, a driver assembly mounted to the rear segment of the base between the side members that in response to manual actuation moves the platform between a lowered and a plurality elevated positions while maintaining the substantial horizontal orientation of the platform. 26. The jack of claim 25 where said substantially rectangular space has a length from 10 to 25 inches and a length width from 10 to 25 inches. 27. The jack of claim 25 where said base has an length of from 30 to 40 inches and the forward segments comprise at least 50 percent of the length of the base and the rear segments comprise at least no more than 25 percent of the length of the base. 28. The jack of claim 25 where said side members, platform and lift arm comprise cast aluminum. 29. The jack of claim 25 where said platform includes a marginal frame with a hollow interior. 30. A jack including a base having a pair of spaced apart substantially planar side members in registration, said base having a front portion and a rear portion narrower than the front portion, a substantially horizontally oriented, substantially rectangular platform overlying a front portion of the base and substantially covering the entire front portion, a pair of support arms each having one end pivotably connect the platform and another end connected to tone of the side members, a lift arm having one end pivotably connected to the platform and another end connected to the rear portion of the base, said lift arm being positioned lengthwise along a longitudinal axis of the jack, and a driver assembly mounted to a rear portion of the base that in response to manual actuation moves the platform between a lowered and a plurality elevated positions, said support arms and lift arm moving in parallel upon actuation of the drive assembly to maintain the platform horizontally oriented. | INCORPORATION BY REFERENCE The inventors incorporate herein by reference any and all U.S. patents, U.S. patent applications, and other documents cited or referred to in this application or cited or referred to in the U.S. patents and U.S. patent applications incorporated herein by reference. DEFINITIONS The words “comprising,” “having,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. “Rectangular-shape” includes square-shape. BACKGROUND OF INVENTION U.S. Pat. No. 6,561,487 discloses a personal vehicle jack having a platform for lifting a personal vehicle such as a motorcycle, all terrain vehicle (ATV), or personal watercraft. The jack is designed to lift the entire vehicle off the floor or ground, with the vehicle balanced on a platform. This jack has stabilizing arms connected to a base to provide side-to-side stability, i.e. to prevent tipping over sideways, and lifting arms for elevating the platform in response to manual actuation of a hydraulic cylinder that operates a substantially vertically orientated ram. A user actuates the jack by stepping on a foot pedal. SUMMARY OF INVENTION This invention has one or more features as discussed subsequently herein. After reading the following section entitled “DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THIS INVENTION,” one will understand how the features of this invention provide its benefits. The benefits of this invention include, but are not limited to: (a) a light weight, compact and sturdy jack, (b) lower costs to manufacture due to reduction in parts and use of conventional components, and (c) ease of assembly. Without limiting the scope of this invention as expressed by the claims that follow, some, but not necessarily all, of its features are: One, the jack of this invention in one embodiment is designed to lift a maximum load weight of about 2500 pounds and weighs less than about 85 pounds. In an elevate position, the entire load is above ground level. Two, the jack includes a base that may be cast of metal, for example, aluminum. The base may have a pair of spaced apart, unitary, rigid, substantially planar side members each with a lower edge, at least a portion of each lower edge being adapted to rest on ground during use of the jack. Three, each side member may have a forward segment and a rear segment. The side members may each be bent to form the forward and rear segments. The rear segments may lie inward from the forward segments. The forward segments may be separated by a first predetermined distance and may be substantially parallel and in substantial registration. Each forward segment may have a front end, a rear end, and a predetermined length. The predetermined length of each forward segment may be substantially equal and the front ends may be in substantial alignment and the rear ends may be in substantial alignment. The rear segments may be substantially parallel, separated by a second predetermined distance that is less than the first predetermined distance. The rear segments may be in substantial registration. A stiffening element, for example, an axle may extend between the forward ends of the forward segments, and the axle may carry a pair of wheels that lie outboard of the side members. The rear segments may also include one or more wheels. Four, each side member may include an intermediate segment between its forward and rear segments. The intermediate segments may slant inward towards each other to connect the forward segment and rear segment of each side member. The side members may be mirror images of each other. Five, the base may have a length of from about 30 to about 40 inches and the forward segments may comprise at least about 50 percent of the length of the base and the rear segments comprise no more than about 50 percent of the length of the base. The intermediate segments may comprise no more than about 25 percent of the length of the base. Six, the jack includes a substantially horizontally oriented platform that may be cast metal, for example, aluminum. The platform may have a forward end, a rear end, opposed sides, and an upper surface adapted to support a load in an elevated position with the entire load above ground level. The platform may have a width that is substantially equal to the predetermined distance between the forward segments and a length that is substantially equal to the predetermined length of the forward segments. The platform may include a marginal frame with a hollow interior. This platform may have a substantially rectangular-shaped configuration with dimensions that are about equal to or slightly less than the dimensions of a rectangular space defined by the forward segments. For example, this substantially rectangular space situated between the forward segments may have a length from about 10 to about 25 inches and a width from about 10 to about 25 inches. Seven, a pair of support arms may each be connected between one side member and the platform. Each support arm may have one end pivotably connected to the forward end of the platform and another end pivotably connected to an intermediary portion of a forward segment of the side member to which the support arm is connected. Eight, a lift arm elevates the platform. The lift arm includes a forward end pivotably connected to the platform. This forward end may be connected to the rear end of the platform at a central portion thereof. The lift arm includes also a rear end pivotably mounted between the rear segments of the side members. The lift arm may be positioned lengthwise along a longitudinal axis of the jack. Nine, a driver assembly actuates the lift arm. This driver assembly may be mounted to the base between the rear segments of the side members. The driver assembly may include a hydraulic cylinder having ram element coupled to the lift arm. The ram element in response to manual actuation moves substantially horizontal, causing the platform to move between a lowered position and a plurality of different elevated positions. Ten, the support arms and lift arm move in unison and substantially parallel to each other so said platform maintains a substantially horizontal orientation as it moves between lowered and elevated positions. Eleven, the jack may include a detachable, elongated safety stop member that is manually detached and, when in an elevated position, is located so that at least a portion thereof engages a top edge of the base if the platform abruptly returns to the lowered position. In other words, the drive assembly fails, and the platform rapidly falls towards the ground, the safety stop member breaks this fall. These features are not listed in any rank order nor is this list intended to be exhaustive. DESCRIPTION OF DRAWING Some embodiments of this invention, illustrating all its features, will now be discussed in detail. These embodiments depict the novel and non-obvious jack of this invention as shown in the accompanying drawing, which is for illustrative purposes only. This drawing includes the following figures (FIGS.), with like numerals indicating like parts: FIG. 1 is a left hand perspective view of a jack according to one embodiment of this invention. FIG. 2 is a right hand perspective view of the jack shown in FIG. 1. FIG. 3 is a top plan view of the jack in FIG. 1. FIG. 4 is a side view of the jack in FIG. 1. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 3 illustrating movement of the support arms, platform, lift arm, and handle. FIG. 5A is an enlarged, fragmentary view taken along line 5A in FIG. 5. FIG. 6 is an exploded, perspective view of the jack shown in FIG. 2. FIG. 7 is a perspective view of a drive assembly according to one embodiment of this invention. FIG. 8 is an exploded, perspective view of the drive assembly shown in FIG. 7. FIG. 9 is a perspective view of a grip pad according to an embodiment of this invention showing the underside of the grip pad. FIG. 10 is a perspective view of a support arm according to an embodiment of this invention showing the underside of the support arm. FIG. 11 is a perspective view showing the underside of the jack depicted in FIG. 1, with one side of the base removed. FIG. 12 is a perspective view of the lift arm according to an embodiment of this invention. DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THIS INVENTION As shown in FIGS. 1-4 and 6, one embodiment of this invention, a jack 10, includes a base 12, a horizontally oriented platform 18 when the jack is resting on ground that overlies a front portion of the base, a pair of support arms 114, 116 connecting to the platform and base, and a lift arm 14 connected between the platform and a drive assembly 16 mounted at or near a rear portion of the base. In accordance with one feature of this invention, the jack is light-weight, weighing less than about 85 pounds, and is designed to lift a light weight load such as a personal vehicle completely off the ground. Typically, the load does not exceed about 2500 pounds. Moreover, to reduce costs, standard components are used such as the drive assembly 16, commonly used in floor jacks that lift, for example, one end of an automobile but are not suited to lift a personal vehicle completely off the ground. To reduce weight, the base 12, platform 18, and lift arm 14 are cast from aluminum. Using such cast metal components not only reduces weight, but also eliminates many parts commonly found in conventional personal vehicle jacks. As illustrated best in FIG. 6, the base 12 includes two separate components, a left side 80 and a right side 90, that are substantially mirror images of each other. Each side 80, 90 has a forward substantially planar segment 82, 92, a substantially planar rear segment 84, 94 that lies inward of the forward segment, and a substantially planar intermediate segment 86, 96 that connects the forward and rear segments. There are substantially triangular shaped outer braces 88, 98 (FIG. 3) integral with exteriors of the sides 80, 90, respectively, the brace 88 extending along the exterior of the intermediate segment 86 and its adjacent rear segment 84 and the brace 98 extending along the exteriors of the intermediate segment 96 and its adjacent rear segment 94. As best illustrated in FIG. 3 and 11, there is a substantially wedge shaped inner brace 87, 97 integral with the interiors of each side 80, 90, respectively. The inner braces 87, 97 each comprise a block having a triangular portion 87a, 97a, a rectangular portion 87b, 97b integral with triangular portion, and a flange 87c, 97c. As best depicted in FIG. 11, each flange 87c, 97c along with an adjacent portion of a side 80, 90, as the case may be, form a yoke Y1. There are holes 182a in each of these flanges 87c, 97c that are aligned with each other and with adjacent holes 182 in the sides 80, 90. The rectangular portions 87b, 97b are integral with the forward segments 82, 92 (FIG. 3) and the triangular portions 87a, 97a (FIG. 3) are integral with the intermediate segments 86, 96, respectively. The flanges 87c, 97c may be located at about the midpoint of the left 80 and right 90 sides, respectively. As illustrated best in FIGS. 3 and 6, the forward segments 82, 92 are parallel, of equal lengths, in registration, and equidistance from the longitudinal axis X (FIG. 3) of the jack 10. Each forward segment 82, 92 forms a substantially vertical wall when the jack 10 is resting on ground, with a hole 82a, 92a (FIG. 6) nearby the fronts 82b, 92b (FIG. 6), respectively, a hole 180 (only one shown) nearby the intermediate segment 86, 96, respectively. As shown in FIG. 3, the forward segments 82 and 92 lie outward O of the platform 18 where the distance between the forward segments is slightly greater than the width w1 (FIG. 3) of the platform. The distance d1 between the forward segments 82, 92 is from about 10 to about 25 inches and the length l1 of each forward segments 82, 92 is from about 10 to about 25 inches. These dimensions define a rectangular area over which the platform 18 lies and the platform may be substantially rectangular and have dimensions about equal to or slightly less (no more than about 5 percent) than this area. As illustrated best in FIGS. 3 and 6, the rear segments 84 and 94, which are parallel and of equal lengths and in registration. Each form a substantially vertical wall when the jack 10 is resting on ground, with a hole 84a, 94a nearby the fronts 84b, 94b (FIG. 6) and tops 84c, 94c (FIG. 6) of each segment and another hole 84d, 94d nearby the middle bottom 84e, 94e of each segment. The rear segments 84 and 94 each lie laterally between the forward segments 82, 92 and straddle the longitudinal axis X of the jack 10. Each rear segment may be equidistance from this axis, typically from about 5 to about 10 inches from the longitudinal axis X. The intermediate segments 86 and 96 may slant inward towards each other to connect the forward segments 82, 92 and rear segments 84, 94, respectively. These intermediate segments 86 and 96 form substantially vertical walls and they have equal lengths from about 8 to about 12 inches. The forward segments 82 and 92, intermediate segments 86 and 96, and rear segments 84 and 94 may slope upward from the forward to rear segments to increase gradually in height. The height of these segments typically ranges from about 3 to about 7 inches. As shown best in FIGS. 1 and 6, the platform 18, which may be cast from aluminum, comprises (a) a substantially rectangular, horizontally oriented, rectangular frame 48 having a pair of yokes 50, 52 each near a front corner of the platform and extending from an underside 48e (FIG. 11) of the forward end 48a of the platform, (b) a central, rectangular shaped opening 54, (c) pair of opposed sides 48c, 48d, and (d) a yoke Y2 (FIG. 11) including a pair of opposed, parallel walls 60, 62 extending along the underside 48e of the platform inward from the rear end 48b of the platform. An open end 50a, 52a (FIG. 1) of each yoke 50, 52 faces downward, and a pair of arms 50b, 50c and 52b, 52c (FIG. 6) of each yoke has a hole 50d, 50e and 52d, 52e, respectively. Each of the sides 48c and 48d has a horizontally orientated hole 56a, 58a near the rear end 48b of the platform 18. Each wall 60 and 62 extends from the rear end 48b of the platform 18 to the rectangular opening 54 of the platform, and each has a hole 60a, 62a that is aligned with the holes 56a, 58a of the outer, opposed sides 48c and 48d. These walls 60 and 62 (FIGS. 2 and 11) are equidistance from the longitudinal axis X and they are separated by a distance that is substantially equal the width w2 (FIG. 12) of the forward end of the lift arm 14. This width w2 ranges from about 3 to about 6 inches. U-shaped tie elements 64 may be attached to the forward end 48a and rear end 48b of the platform 18. Elastic bands (not shown) are wrapped or tie to these tie elements 64 (FIG. 1) and the vehicle being balanced on the platform 18 to hold the vehicle securely to the platform. A pair of laterally adjustable grips pads 64 (FIGS. 1 and 6) may be connected to the top side 18a of the platform 18. As illustrated in FIG. 9, each grip pad 64 comprises a metal plate 66 with a coating 68 preferably made from a non-slippery substance such as rubber applied to the top side 66a of the metal plate, and a pair of spaced-apart metal blocks 70, 72 located on the bottom side 66b of each of the metal plates. A threaded cylinder 70a, 72a extends outward from each of the metal blocks 70, 72, respectively. The grip pads 64 may be coupled to the platform 18 by inserting the threaded cylinders 70a, 72a through slots 74a, 74b, 74c, 74d of the platform, respectively, and attaching a nut (not shown) to each of the threaded cylinders. The location of each of the grip pads 64 on the platform 18 may be varied by sliding the threaded cylinders 70a, 72a along the slots 74a, 74b, 74c, 74d until a desired position is achieved. This provides more or less exposure of the rectangular opening 54 as may be need to accommodate the undercarriage of a vehicle being supported by the platform 18 or to better balance the vehicle on the platform. Wheels 100, 102, 104 and 106 may be attached to the base 12. A stiffening rod 108, also functioning as an axle, may be attached to the left side 80 and right side 90 of the base 12 by passing a left end 108a and right end 108b of the rod through holes 82a, 92a, respectively. A secondary stiffening rod 107 may also extended between the left side 80 and right side 90 nearby the junctions between the forward segments 82 and 92 and the intermediate segments 86 and 96 of these sides. The front wheels 100, 102 may be attached to the rod 108 outboard of the left side 80 and right side 90. Referring to FIG. 3, the front wheels 100, 102 also each lie outward O of the platform 18. The rear wheels 104, 106 are caster type wheels and may be detachably connected to the rear segments 84, 94 of the base 12 by wheel mounts 110, 112 (FIG. 6). These wheel mounts 110, 112 are screwed or otherwise attached to the outer sides 80a, 90a of the rear segments 84, 94 of the base, respectively. In another embodiment, the wheel mounts may be integral (not detachable) with the rear segments 84, 94 of the base 12. Referring to FIG. 3, each of the wheel mounts 110, 112 lie inside of the forward segments 82, 92 of the base 12 but are outboard of the rear segments 84, 94. As shown best in FIGS. 2, 6 and 10, a pair of support arms 114 and 116 each have opposed ends pivotably connected to the base 12 and platform 18. The support arms 114, and 116 each comprise an elongated bar having horizontally, orientated holes 114a, 114b (FIG. 10) and 116a, 116b at opposed ends 114c, 114d and 116c, 116d, respectively. A cylindrical stop member 118, 120 may be located in a channel 114e, 116e of each support arm 114, 116, nearby ends 114d and 116d, respectively. Pivot pins P1 (FIG. 5) extend through holes 114a, 116a in the support arms 114, 116 and the holes 50d, 50e and 52d, 52e in the yokes 50, 52 along the forward end 48b of the platform 18. In a similar manner, pivot pins P2 (FIG. 5) extend through holes 114b and 116b and the holes 180 in the sides 80,90 and the holes 182a in the flanges 87c, 97c. Each support arm 114, 116 is thus pivotably connected at opposed ends to the platform 18 and intermediary portions of the forward segments 82,92 of the base 12. Referring to FIGS. 6, 11 and 12, the lift arm 14 is a rigid, unitary member that may be cast from aluminum. It is connected to pivot at its opposed forward end 14a and rear end 14b respectively to the platform 18 and the drive assembly 16. The lift arm 14 includes a left triangular wall 124 and a right triangular wall 122 that are substantially parallel. It also includes a front connector 126 at the forward end 14a, a middle connector 128, and rear connecter 130 at the rear end 14b; all extending between the walls 122 and 124 substantially at a right angle. These triangular walls 122, 124 each have a horizontally orientated hole 125, 127 near the front ends 122a, 124a aligned with each other, a horizontally orientated hole 146, 148, near the rear of these walls aligned with each other, and a horizontally orientated hole 200, 202 between the middle connector 128 and the rear end 14b of the lift arm. The rear connector 130 provides a housing for the drive assembly 16. As best shown in FIGS. 11 and 12, the rear connector 130 includes a top plate 132 (FIGS. 1 and 2), a rear wall 134 and a parallel front wall 134a, each having concave edges E1 and E2 respectively, and a left sidewall 136 and a right sidewall 138. The top plate 132 is U-shaped and is flush with the top edges of the triangular walls 122 and 124. The top plate 132 is open-ended facing forward F. The rear wall 134 is U-shaped, having an open end facing towards the bottom sides 122d, 124d of the triangular walls 122 and 124. The sidewalls 136 and 138 are spaced from adjacent portions of the rear segments 84 and 94 to provide a space for links 150 and 152 of the drive assembly 16. There is in each sidewall 136,138 a horizontally, orientated hole 140 (only one shown in FIG. 12) passing therethrough. The holes 140 in each of these sidewalls 136 and 138 are aligned. There are holes 141 (only one shown in FIG. 12) in the triangular walls 122 and 124 that are aligned with the holes 140. A cylindrical boss 144a (only one shown in FIG. 12) projects outward from each of the triangular walls 122 and 124 near the rear end 14b and there are holes 144 in each of these bosses that are aligned. As illustrated in FIG. 3, the bosses 144a act as spacers to maintain the rear segments 84,94 and the triangular walls 122, 124 a fixed distance way from each other. As shown in FIG. 3, to connect the forward end 14a of the lift arm 14 to a central portion of the rear of the platform 18, the holes 125 and 127 at the forward end of the lift arm 14 are aligned with the holes 60a, 62a in the walls 60, 62 of the yoke Y2 (FIG. 11) and a pivot pin P3 is then inserted into these aligned holes. In an alternate embodiment, the forward end l4a of the lift arm 14 may be pivotably connected to the platform 18 using a rod that passes through holes 125 and 127 of the lift arm, holes 60a and 62a, as well as holes 56a and 58a, of the platform. The rear end 14b of the lift arm 14 is pivotably connected to the base 12 by a dowel 172 that extends through the aligned holes 144 in the bosses 144a. The opposed ends 172a and 172b respectively of the dowel 172 are received in the aligned holes 84a and 94a in the rear segments 84 and 94. When the drive assembly 16 actuates the lift arm 14, the lift arm pivots about the dowel 172. As depicted in FIGS. 5A, 7 and 8, the drive assembly 16 is of a conventional design and includes a ram 19 disposed within a cylinder 20, a fluid chamber 22, and a manually operated pump 24. The longitudinal axis of the cylinder 20 is substantially horizontally orientated. The pump 24 is partially disposed within the fluid chamber 22, and includes a detachable handle 26, a pump core 28, pump case 30, a spring 32, a piston cover 34 and a discharge valve rod 36 for a valve (not shown). The handle 26 is attached to the pump case 30 by a handle base 25. The cylinder 20 is encased in a sleeve 38 and it extends from the front side 22a of the fluid chamber 22. This cylinder 20 has, for example, a circular cross-section. The fluid chamber 22 has an internal cavity (not shown) holding hydraulic fluid and a pair of cylindrical caps 40, 42, closing the cavity, each cap having a threaded portion 40a, 42a, respectively, that is used to attach the caps to a main body 44 of the fluid chamber. The main body 44 may be box-like in shape, having a left wall 44a and a right wall 44b separated by a distance that is about equal to the distance between the two rear segments 84 and 94 of the base 12. By inserting the caps 40 and 42 into the holes 84d and 94d, respectively, the drive assembly 16 is connected between the rear segments 84 and 94 abutting, respectively, the left wall 44a and right wall 44b (FIG. 8) of the drive assembly 16. A removable fluid plug 46 seals an access port 46a that enables fluid to be put into the fluid chamber 22. The ram 19 is mounted to slide forward and rearward within the cylinder 20 and the cross-section of the ram may be identical in shape as the interior I of the cylinder. While one embodiment of a drive assembly 16 is described, other types of drive assemblies may be used such as described in U.S. Pat. Nos. 2,629,583, 3,807,694, and 4,018,421. The sleeve 38 abuts the upper edges E1 and E2 of the rear and front walls 134 and 134a, respectively The lift arm 14 is connected to the drive assembly 16 by means of a U-shaped member 157 including a block 154 having a pair of fingers 154a, 154b, each pivotably connected to one of a pair of links 150 and 152 that extend towards the main body 44 of the fluid chamber 22. The block 154 is connected to a front end 19a (FIG. 7) of the ram 19. Each link 150, 152 comprises an elongated, rigid bar each having opposed holes 153 and 156, and 158 and 160, respectively. The fingers 154a and 154b, fit into the holes 153 and 158, respectively, with the fingers serving as pivot pins. The other ends of the links 150 and 152 are pivotably attached to the rear connecter 130. A pivot pin P4 is aligned with the aligned holes 140 and 141 respectively in the left sidewall 136 of the rear connector 130 and right triangular wall 122 and these aligned holes are aligned with the hole 156 in the link 150. This pivot pin P4 extends through these aligned holes 140, 141, and 156. A pivot pin P5 is aligned with the aligned holes 140 and 141 respectively in the right sidewall 138 of the rear connector 130 and left triangular wall 124 and these aligned holes are aligned with the hole 160 in the link 152. This pivot pin P5 extends through these aligned holes 140, 141, and 160. Referring to FIG. 5, with the platform 18 in its lowered position shown in dotted lines, the drive assembly 16 is manually actuated to move the platform to one of a plurality of different elevated positions shown in solid lines. The ram 19 is now in a fully retracted condition. To achieve this the user moves the handle 26 first in a downward stroke in a clockwise (CW) direction whereby fluid is moved by the pump 24 from the fluid chamber 22 into the cylinder 20. Moving the handle 26 in an upward stroke in a counter-clockwise (CW) direction does nothing. When fluid enters the cylinder 20, the ram 19 moves outward along the longitudinal axis of the cylinder, pushing the block 154 outward towards the main body 44 of the fluid chamber 22, causing the links 150 and 152 to pull on the lift arm 14. This causes the lift arm 14 to pivot about the dowel 172, rotating in a clockwise direction as viewed in FIG. 5 to move the platform 18 from the lowered position to the elevated position. As the lift arm 14 rotates, the support arms 114 and 116 rotate in unison therewith and parallel thereto maintaining the platform 18 substantially horizontal as it is elevated. Repeatedly reciprocating the handle 26 in the clockwise and counter-clockwise direction will continue to elevate the platform 18. Stop members (not shown) are located on the base 12 to limit rotation of the handle 26. To lower the platform 18 to return it to its lowered position shown in dotted lines in FIG. 5, the handle 26 is twisted to actuate the discharge valve rod 36, allowing fluid to move slowly from the cylinder 20 into the fluid chamber 22, with the platform lowering as the fluid returns to the fluid chamber. The handle 26 has a sufficient length to allow a user that is standing upright to actuate the handle without having to significantly adjust his or her posture. When the platform 18 is elevated, it is desirable to prevent its returning to the lowered position in the event a failure occurs in the drive assembly 16, for example, hydraulic fluid rapidly escaping from the cylinder 20. One way is to provide a safety stop member such as, for example, a detachable, elongated shaft 206 that is mounted to the base 12 for example. With the platform 18 elevated, the shaft 206 is detached and inserted in the aligned holes 200 and 202. If the platform 18 suddenly moves downward because of the failure in the drive assembly 16, the outer ends 206a and 206b of the shaft 206 are located to engage a top edge of the base 12 to prevent the elevated platform from abruptly returning to the lowered position shown in solid lines in FIG. 5. SCOPE OF THE INVENTION The above presents a description of the best mode contemplated of carrying out the present invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use this invention. This invention is, however, susceptible to modifications and alternate constructions from that discussed above which are fully equivalent. Consequently, it is not the intention to limit this invention to the particular embodiments disclosed. On the contrary, the intention is to cover all modifications and alternate constructions coming within the spirit and scope of the invention as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of the invention: | <SOH> BACKGROUND OF INVENTION <EOH>U.S. Pat. No. 6,561,487 discloses a personal vehicle jack having a platform for lifting a personal vehicle such as a motorcycle, all terrain vehicle (ATV), or personal watercraft. The jack is designed to lift the entire vehicle off the floor or ground, with the vehicle balanced on a platform. This jack has stabilizing arms connected to a base to provide side-to-side stability, i.e. to prevent tipping over sideways, and lifting arms for elevating the platform in response to manual actuation of a hydraulic cylinder that operates a substantially vertically orientated ram. A user actuates the jack by stepping on a foot pedal. | <SOH> SUMMARY OF INVENTION <EOH>This invention has one or more features as discussed subsequently herein. After reading the following section entitled “DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THIS INVENTION,” one will understand how the features of this invention provide its benefits. The benefits of this invention include, but are not limited to: (a) a light weight, compact and sturdy jack, (b) lower costs to manufacture due to reduction in parts and use of conventional components, and (c) ease of assembly. Without limiting the scope of this invention as expressed by the claims that follow, some, but not necessarily all, of its features are: One, the jack of this invention in one embodiment is designed to lift a maximum load weight of about 2500 pounds and weighs less than about 85 pounds. In an elevate position, the entire load is above ground level. Two, the jack includes a base that may be cast of metal, for example, aluminum. The base may have a pair of spaced apart, unitary, rigid, substantially planar side members each with a lower edge, at least a portion of each lower edge being adapted to rest on ground during use of the jack. Three, each side member may have a forward segment and a rear segment. The side members may each be bent to form the forward and rear segments. The rear segments may lie inward from the forward segments. The forward segments may be separated by a first predetermined distance and may be substantially parallel and in substantial registration. Each forward segment may have a front end, a rear end, and a predetermined length. The predetermined length of each forward segment may be substantially equal and the front ends may be in substantial alignment and the rear ends may be in substantial alignment. The rear segments may be substantially parallel, separated by a second predetermined distance that is less than the first predetermined distance. The rear segments may be in substantial registration. A stiffening element, for example, an axle may extend between the forward ends of the forward segments, and the axle may carry a pair of wheels that lie outboard of the side members. The rear segments may also include one or more wheels. Four, each side member may include an intermediate segment between its forward and rear segments. The intermediate segments may slant inward towards each other to connect the forward segment and rear segment of each side member. The side members may be mirror images of each other. Five, the base may have a length of from about 30 to about 40 inches and the forward segments may comprise at least about 50 percent of the length of the base and the rear segments comprise no more than about 50 percent of the length of the base. The intermediate segments may comprise no more than about 25 percent of the length of the base. Six, the jack includes a substantially horizontally oriented platform that may be cast metal, for example, aluminum. The platform may have a forward end, a rear end, opposed sides, and an upper surface adapted to support a load in an elevated position with the entire load above ground level. The platform may have a width that is substantially equal to the predetermined distance between the forward segments and a length that is substantially equal to the predetermined length of the forward segments. The platform may include a marginal frame with a hollow interior. This platform may have a substantially rectangular-shaped configuration with dimensions that are about equal to or slightly less than the dimensions of a rectangular space defined by the forward segments. For example, this substantially rectangular space situated between the forward segments may have a length from about 10 to about 25 inches and a width from about 10 to about 25 inches. Seven, a pair of support arms may each be connected between one side member and the platform. Each support arm may have one end pivotably connected to the forward end of the platform and another end pivotably connected to an intermediary portion of a forward segment of the side member to which the support arm is connected. Eight, a lift arm elevates the platform. The lift arm includes a forward end pivotably connected to the platform. This forward end may be connected to the rear end of the platform at a central portion thereof. The lift arm includes also a rear end pivotably mounted between the rear segments of the side members. The lift arm may be positioned lengthwise along a longitudinal axis of the jack. Nine, a driver assembly actuates the lift arm. This driver assembly may be mounted to the base between the rear segments of the side members. The driver assembly may include a hydraulic cylinder having ram element coupled to the lift arm. The ram element in response to manual actuation moves substantially horizontal, causing the platform to move between a lowered position and a plurality of different elevated positions. Ten, the support arms and lift arm move in unison and substantially parallel to each other so said platform maintains a substantially horizontal orientation as it moves between lowered and elevated positions. Eleven, the jack may include a detachable, elongated safety stop member that is manually detached and, when in an elevated position, is located so that at least a portion thereof engages a top edge of the base if the platform abruptly returns to the lowered position. In other words, the drive assembly fails, and the platform rapidly falls towards the ground, the safety stop member breaks this fall. These features are not listed in any rank order nor is this list intended to be exhaustive. | 20040331 | 20061121 | 20051006 | 63405.0 | 2 | WILSON, LEE D | JACK | SMALL | 0 | ACCEPTED | 2,004 |
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10,814,476 | ACCEPTED | Method and device for the continuous measurement of the wear of a tire | A method for the continuous measurement of the wear of a tire comprises the steps of measuring a capacitance or an electrical resistance within a tread pattern element of the tire, and deducing the height of the element with the aid of an equation relating the capacitance or resistance to the height, and devices for implementing the method. | 1. A method for the continuous measurement of the wear of a tire, comprising the steps of: measuring capacitance or electrical resistance in a tread pattern element of the tire, and deducing the height of the element from an equation relating the capacitance or resistance to the height. 2. A method according to claim 1, wherein the step of measuring capacitance or resistance values is effected by an acquisition module, said acquisition module being provided within the tire. 3. A method according to claim 2, wherein the tire is fitted on an automobile vehicle and is mounted on a wheel thereof, the step of measuring capacitance or resistance in the tread pattern element is effected by remotely energizing the acquisition module with an interrogation module mounted on one of the wheel or a fixed part of the vehicle close to the wheel, and the method further comprises the step of transmitting to the interrogation circuit the capacitance or resistance measurement acquired by the module through an inductance coupled to the acquisition module. 4. A method according to claim 1, wherein the tire is fitted to an automobile vehicle and is mounted on a wheel thereof, the step of measuring capacitance is effected by determining an in-tune frequency of a passive resonance circuit comprising at least one capacitor formed by the tread pattern element and an inductance connected to the capacitor in the tread of the tire using an interrogation circuit mounted on the wheel or on a fixed part of the vehicle close to the wheel. 5. A tread pattern element of a tread for a tire, the element comprising a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element in a direction normal to the crown, the crown being intended, when the tire is rolling on a rolling surface, to be in contact at one time or another with the surface, wherein the element comprises at least two conducting layers disposed face to face with one another and having a same height and at least one insulating layer consisting respectively of electrically conducting and insulating rubber compositions, the at least one insulating layer being disposed between mutually adjacent conducting layers, the at least one insulating layer having a height which is equal to one of a full height of the conducting layers to form at least one capacitor or less than the full height of the conducting layers to form at least one electrical resistance, said at least one capacitor or resistor having a capacitance or resistance value representative of the height of the element. 6. A tread pattern element according to claim 5, wherein the at least two conducting layers are positioned with one end at a level with the crown and the at least one insulating layer is positioned with one end at one of a level with the crown to form the capacitor or a level below the crown to form the resistor. 7. A tread pattern element according to claim 5, wherein the at least two conducting layers and the at least one insulating layer are positioned with one end at a level with the base. 8. A tread pattern element according to claim 5, wherein the at least two conducting layers and the at least one insulating layer are rectangular and stacked against one another to form a parallelepiped shape. 9. A tread pattern element according to claim 5, wherein the at least two conducting layers and the at least one insulating layer are cylindrically shaped and positioned coaxially one against the other to form a solid cylinder. 10. A tread pattern element of a tread for a tire, the element comprising a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element in a direction normal to the crown, the crown being intended, when the tire is rolling on a rolling surface, to be in contact with the surface, wherein the element comprises an electrically insulating rubber composition and at least two identical wires embedded in the rubber composition and positioned parallel to one another, the at least two identical wires being electrically conducting to form at least one capacitor whose dielectric and armature plates are formed respectively by the insulating composition and by the wires, the capacitor having a capacitance value representative of the height (H) of the element. 11. A tread pattern element according to claim 10, wherein the wires extend from a level with the base at one end to a level with the crown at an opposite end. 12. A tread for a tire, comprising at least one tread pattern element having a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element in a direction normal to the crown, the crown being intended, when the tire is rolling on a rolling surface, to be in contact at one time or another with the surface, wherein the element comprises at least two conducting layers disposed face to face with one another and having a same height and at least one insulating layer consisting respectively of electrically conducting and insulating rubber compositions, the at least one insulating layer being disposed between mutually adjacent conducting layers, the at least one insulating layer having a height which is equal to one of a full height of the conducting layers to form at least one capacitor or less than the full height of the conducting layers to form at least one electrical resistance, said at least one capacitor or resistor having a capacitance or resistance value representative of the height of the element, the tread further comprising an insulating layer arranged radially underneath the tread pattern element to cover a whole of the base of the tread pattern element to insulate the tread pattern element electrically from adjacent rubber composition in the tread. 13. A tread according to claim 12, further comprising an electronic acquisition module connected to the at least one pattern element underneath the pattern element, said electronic acquisition module being adapted to measure one of the capacitance or resistance value and to deduce therefrom a height (H) of the at least one tread pattern element. 14. A tread according to claim 13, wherein the acquisition module is further adapted to emit signals representative of one of the capacitance or resistance value towards a central unit mounted inside a vehicle fitted with the tire. 15. A tread according to claim 13, wherein the acquisition module is further adapted to be remotely energized by an interrogation circuit mounted on one of the wheel or a fixed part of the vehicle close to the wheel, and to cooperate by coupling with an inductance located in the tread, so as to transmit to the interrogation circuit the capacitance measurement acquired by the module. 16. A tire comprising a tread having at least one tread pattern element having a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element in a direction normal to the crown, the crown being intended, when the tire is rolling on a rolling surface, to be in contact at one time or another with the surface, wherein the element comprises at least two conducting layers disposed face to face with one another and having a same height and at least one insulating layer consisting respectively of electrically conducting and insulating rubber compositions, the at least one insulating layer being disposed between mutually adjacent conducting layers, the at least one insulating layer having a height which is equal to one of a full height of the conducting layers to form at least one capacitor or less than the full height of the conducting layers to form at least one electrical resistance, said at least one capacitor or resistor having a capacitance or resistance value representative of the height of the element, the tread further comprising an insulating layer arranged radially underneath the tread pattern element to cover a whole of the base of the tread pattern element to insulate the tread pattern element electrically from adjacent rubber composition in the tread. 17. A tire and wheel assembly for an automobile vehicle, comprising a tire and a wheel on which the tire is fitted, the tire having a tread with a plurality of tread pattern elements each comprising a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element in a direction normal to the crown, the crown being intended, when the tire rolls over a rolling surface, to be in contact with the surface at one time or another, wherein at least one tread pattern element comprises at least two conducting layers disposed face to face with one another and having a common height and at least one insulating layer, the at least two conducting layers comprising an electrically conducting rubber composition and the at least one insulating layer comprising an electrically insulating rubber composition, wherein two mutually adjacent conducting layers are separated by an insulating layer which extends the height of the respective conducting layers in a direction normal to that of the crown, such that the element defines a capacitor having a capacitance value representative of a height (H) of the element, the tread further comprising a resonance circuit comprising an inductance mounted underneath the tread pattern element and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit mounted permanently on the wheel, the interrogation circuit having a frequency scanning energy generator and detection means designed to detect the frequency at which the circuits are in tune, to deduce from that tuned frequency the capacitance value of the capacitor, and to deduce from that capacitance value the height (H) of the tread pattern element. 18. A tire and wheel assembly according to claim 17, wherein the interrogation circuit comprises a frequency scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit, and a resistance. 19. A tire and wheel assembly according to claim 18, wherein said means for detecting the tuning frequency are mounted across the terminals of the resistance to measure the voltage between those terminals. 20. A tire and wheel assembly for an automobile vehicle comprising a tire and a wheel on which the tire is fitted, the tire having a tread which comprises tread pattern elements each with a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element, the crown being intended when the tire is rolling on a rolling surface to be in contact with the surface at one time or another, wherein at least one of the tread pattern elements comprises at least two conducting layers disposed face to face and of the same height and at least one insulating layer, the at least two conducting layers being formed of an electrically conducting rubber composition and the at least one insulating layer being formed of an electrically insulating rubber composition, wherein, mutually adjacent conducting layers are separated from one another by an interposed insulating layer which extends a full height of the conducting layers in a direction normal to that of the crown, so that the element defines a capacitor whose capacitance value is representative of the height (H) of the element, the tread further comprising an acquisition module adapted to measure the capacitance value and which is remotely energized by an interrogation circuit mounted on one of the wheel or a fixed part of the vehicle close to the wheel, and an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit comprising means for deducing from the measured capacitance value height (H) of the tread pattern element and for communicating with a central unit provided in the cockpit of the vehicle. 21. An automobile vehicle having tires whose respective treads each have tread pattern elements, each tread pattern element having a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element, the crown being intended when the tire is rolling on a rolling surface to be in contact with the surface at one time or another, wherein at least one tread pattern element in each tire comprises at least two conducting layers disposed face to face and having a same height and at least one insulating layer, the at least two conducting layers being formed of an electrically conducting rubber composition and the at least one insulating layer being formed of an electrically insulating rubber composition, wherein mutually adjacent conducting layers are separated from one another by an interposed insulating layer which extends a full height of the conducting layers in a direction normal to that of the crown, so that the element defines a capacitor whose capacitance value is representative of height (H) of the element, the tread of each tire further comprising a resonance circuit comprising an inductance mounted underneath the tread pattern element and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit attached permanently to a fixed part of the vehicle close to the tire, the interrogation circuit being provided with a frequency-scanning energy generator and detection means provided for detecting the frequency at which the circuits are in tune, for deducing from this tuned frequency the capacitance value of the capacitor, and for deducing from this capacitance value the height (H) of the tread pattern element, the interrogation circuit also being designed to communicate with a central unit provided in the cockpit of the vehicle. 22. An automobile vehicle according to claim 21, wherein the interrogation circuit comprises a frequency-scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit and a resistance. 23. An automobile vehicle according to claim 22, wherein said means for detecting the tuned frequency are mounted across the terminals of the resistance to measure the voltage across the terminals. 24. An automobile vehicle fitted with tires whose respective treads each have tread pattern elements, each tread pattern element having a base and a crown connected to one another by at least one lateral face which defines a height (H) of the element, the crown being intended when the tire is rolling on a rolling surface to be in contact with the surface at one time or another, wherein at least one tread pattern element of at least one tread comprises at least two conducting layers arranged face to face and having a same height and at least one insulating layer, the at least two conducting layers being formed of an electrically conducting rubber composition and the at least one insulating layer being formed of an electrically insulating rubber composition, mutually adjacent conducting layers being separated from one another by an insulating layer which extends a full height of the conducting layers in a direction normal to that of the crown, so that the element defines a capacitor whose capacitance value is representative of a height (H) of the element, the at least one tread having an acquisition module adapted to measure the capacitance value and which is remotely energized by an interrogation circuit attached permanently to a fixed part of the vehicle close to the tire, and an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit comprising means for deducing from this capacitance value the height (H) of the tread pattern element, the interrogation circuit also being designed to communicate with a central unit provided in the cockpit of the vehicle. | BACKGROUND OF THE INVENTION The present invention concerns a method for the continuous measurement of the wear of a tire. The invention also concerns an element of a tread pattern for a tire which is provided with means to enable continuous measurement of the wear of the element during the rolling of the tire over a rolling surface, a tread comprising the element, and a tire comprising the tread. The invention also concerns a fitted assembly for an automobile vehicle, and such a vehicle which comprises means for measuring the wear of the tire continuously and in real time. It is known to provide devices for detecting wear of the tread patterns of tires for automobile vehicles. German Patent DE-A-197 45 734 (see FIGS. 2 and 3 thereof) discloses a tire whose tread comprises in its mass a plurality of metallic wires which form electrically conducting loops that extend respectively to different heights within a pattern rib of the tread, and which are connected to a detection circuit underneath the rib. During the rolling of a vehicle fitted with this tire, these loops are broken one after the other to form open switches and the detection circuit delivers a signal representative of these breaks to an evaluation unit present in the vehicle. A major disadvantage of this wear detector is that the wear is detected discontinuously because it is a function of the number of loops successively broken (i.e. the number of open switches). Another disadvantage of this wear detector is that it seems very difficult for a person engaged in the field to manufacture it in a precise manner. In the context of the present description, the “fixed part” of a vehicle will be understood as the chassis of the vehicle and the suspension rods, as opposed to the “rotating parts” which include the wheels, tires and hubs. SUMMARY OF THE INVENTION One aspect of the present invention is a method for the continuous measurement of the wear of a tire, i.e., one which enables the wear to be measured at any time, whether during rolling of a vehicle fitted with the tire, or else when the vehicle is at rest. According to the invention, this method consists in measuring the capacitance or electrical resistance inside a tread pattern element of the tire, and deducing the height of the element by virtue of an equation relating the capacitance or resistance to the height. Preferably, the process consists in using as the tread pattern element an element formed such that its capacitance or resistance is directly proportional to the height of the element. In other words, the height is a linear function of the capacitance or resistance. Consequently, the acquisition module does not require a complex algorithm (linear transfer function) to measure the height of the tread pattern element. In this description “tread pattern element” means any relief element of the tire tread which is intended to be in contact with the rolling surface at any time (i.e. from when rolling begins, or after wear of the element has started). Thus, the element can consist of a block of substantially parallelepiped or cylindrical shape, or a “rib” or circumferential ridge whose cross-section varies (i.e. extending over all or part of the circumference of the tread). According to one example embodiment of the invention, the method consists in effecting the capacitance or resistance measurement by providing within the tire an electronic acquisition module which is connected to the tread pattern element underneath the tread. According to a first embodiment of the invention in which the tire is mounted on a wheel and fitted to an automobile vehicle, the method consists essentially in effecting a capacitance measurement relating to the pattern element, by determining the tuning frequency of a passive resonance circuit comprising at least one capacitor formed by the pattern element and an inductance connected to the capacitor in the tread of the tire, by means of an interrogation circuit mounted on the wheel or on a fixed part of the vehicle that is adjacent to the wheel. According to a second embodiment of the invention in which the tire is again mounted on a wheel and fitted on an automobile vehicle, the method consists in effecting a capacitance measurement relating to the tread pattern by remote energizing of the acquisition module via an interrogation circuit mounted on the wheel or on a fixed part of the vehicle that is adjacent to the wheel, and transmitting to the interrogation circuit the capacitance measurement acquired by the module via an inductance coupled within the tire to the acquisition module. According to a first example embodiment of the invention, the method consists in measuring the capacitance within the tread pattern element, by providing that at least one capacitor is formed in the element. A capacitor in accordance with the invention can consist of electrically conducting plates forming armatures separated from one another by an electrically insulating rubber composition which forms a dielectric for the capacitor. Each of these plates can be metallic, consisting for example of copper or brass or another metal compatible with the rubber used, or it can consist of an electrically conducting rubber composition, for example one containing a sufficient quantity of carbon black as the reinforcing filler. A capacitor can alternatively consist of metallic wires, for example of copper or brass. Note that the use of a capacitor in the tread pattern element enables the energy consumed to be minimized, since the reactive power characterizes the capacitor. This energy consumption can advantageously be minimized by interrogating the acquisition module when the vehicle is stopped (for example, each time it is started, by inserting the ignition key), by means of a central unit mounted inside the vehicle. According to a second example embodiment of the invention, the method consists in measuring the resistance in the tread pattern element, by providing that at least one electrical resistance is formed in the element. As before, the resistance can comprise electrically conducting plates (metallic, or of electrically conducting rubber) or else metallic wires such as those mentioned earlier. Preferably, the plates mentioned above in relation to the capacitor or resistance are flat; however, other shapes or contours are possible. Another purpose of this invention is to propose a tread pattern element for a tire, the element comprising a base and a crown connected to one another by at least one lateral face which defines the height of the element, the crown being intended, when the tire is rolling over a rolling surface, to be in contact with the ground at one time or another, and such that in relation to an acquisition module to which it is connected, the structure of the element makes it possible to measure the wear of the tread continuously. To that end, a tread pattern element according to the invention comprises n conducting layers face to face with one another and of the same height (n being an integer≧2) and n−1 insulating layer(s) which consist respectively of electrically conducting and insulating rubber compositions, two adjacent conducting layers being separated from one another by an insulating layer which extends a complete height of the conducting layers (case (i)) or part of the height of the conducting layers (case (ii)) in a direction normal to that of the crown, such that the element defines at least one capacitor in the case (i) or at least one electrical resistance in the case (ii), which respectively have a capacitance C or resistance R value representative of the height of the element. It follows that the height of the tread pattern element can be determined at any time during rolling from the value of the capacitance of the capacitor(s) or resistance(s) that it forms, this capacitance or resistance value being measurable by an electronic acquisition module which is connected to the tread pattern element underneath the latter, inside the tread. Note that in the case where the pattern element consists of a circumferential “rib” or ridge of given cross-section, the aforesaid conducting or insulating layers extend over the full circumference of the tread. Note also that the capacitors or resistors formed in such tread pattern elements advantageously consist of the rubber compositions customarily used for making tire treads, which facilitates the fabrication of the treads and so minimizes their cost. Furthermore, when the capacitor or resistor is made of rubber, this imparts better cohesion to the tread of the corresponding tire (compared with the cohesion between metallic parts and rubber parts). The improved cohesion results in performances of the tire, such as wear or grip, which are not appreciably degraded during rolling. According to an example embodiment of the invention, the conducting layers are positioned with one end on a level with the crown, and each insulating layer has one end on a level with the crown in the case (i) capacitor or the one end a distance away from the crown in the case (ii) resistor. As a result, the wear of the tread pattern element can be measured continuously from the beginning of rolling, for a tread pattern element in contact with the rolling surface from the time rolling begins. The conducting layers on the one hand, and the at least one insulating layer on the other hand, have a radially-inner end on a level with the base. According to a first embodiment of the invention, the conducting layers and insulating layer(s) are rectangular and are stacked over one another so as to impart a parallelepiped shape to the element. A tread pattern element according to this embodiment of the invention can form a capacitor, if it consists of two electrically conducting layers of rectangular shape (whether parallel or not) applied against an electrically insulating layer such that the three layers are face to face and all three have a first end on a level with the base, and a second, opposite end on a level with the crown. The armature plates and the dielectric of the capacitor consist respectively of the conducting layers and the insulating layer. As a variant, a tread pattern element according to the invention can form several capacitors in series, for example comprising three electrically conducting layers which are identical and of rectangular shape, with two electrically insulating layers applied respectively between a first and a second pair of adjacent conducting layers. All these layers are again face to face with one another with a first end on a level with the base on the one hand and a second opposite end on a level with the crown on the other hand. The armature plates and the dielectric of this capacitor consist respectively of the conducting layers and the insulating layers. A tread pattern element according to the invention can also form a resistance, comprising two identical and rectangular electrically conducting layers applied on an electrically insulating layer, such that the layers are face to face with one another and all three have a first end on a level with the base of the tread pattern element. The insulating layer only partially extends the height of the conducting layers, so that the conducting layers are connected to one another by a third, median conducting layer which extends the insulating layer to a given height (representing the height of the wear to be measured) in the direction of the crown of the tread pattern element, the three conducting layers having radially outer ends on a level with the crown. In a second embodiment according to the invention, the conducting and insulating layer(s) are concentric and are positioned one inside the other, whether or not they are closed upon themselves. For example, the layers can be cylindrical and positioned coaxially against one another, so as to confer upon the element the geometry of a solid cylinder or part-cylinder. A tread pattern element according to this variant of the invention can for example form a capacitor, and consists of cylindrical and coaxial layers of the same height comprising two electrically conducting layers between which is applied an electrically insulating layer, such that these layers are face to face and having a first end on a level with the base and a second opposite end on a level with the crown. The armature plates and the dielectric of this capacitor consist respectively of the conducting layers and the insulating layer. According to another aspect of the invention, the element consists of an electrically insulating rubber composition in which are embedded at least two identical, electrically conducting wires parallel to one another, so as to form at least one capacitor (a single capacitor, or several capacitors arranged in series) whose dielectric and armature plates are formed respectively by the insulating composition and the wires, the capacitor having a capacitance value at any moment which is representative of the height of the element at that moment. According to an example embodiment of the invention, the wires have a first end on a level with the base, and an opposite end on a level with the crown. It follows that the height of this tread pattern element can be determined during rolling, from the capacitance value of the capacitor(s) that it forms, this capacitance being measured by an electronic acquisition module connected to the tread pattern element under the latter, within the tread. A tread of a tire according to the invention is such that it comprises at least one tread pattern element such as one of those described above. Note that when the tread pattern element consists of a capacitor or resistance formed of the conducting layers and insulating layer(s) of rubber and if the composition of the tread or the tread underlayer has a reduced resistivity (for example, similar to that of the conducting layers), then the tread or its underlayer must necessarily also comprise an insulating layer arranged radially underneath the tread pattern element so as to cover its base entirely, whose purpose is to insulate the tread pattern element electrically from the tread or underlayer composition. This insulating layer, whose thickness is advantageously small, can for example consist of a rubber composition whose resistivity is analogous to that of the at least one insulating layer of the capacitor or resistance forming the tread pattern element (i.e. with resistivity for example between 1012 and 1015 Ω.cm). According to another characteristic of the invention, the tread comprises in its mass an electronic acquisition module which is connected to the at least one element underneath the latter and is designed to measure the value of the capacitance or resistance of the capacitor(s) in the case (i) or of the resistance(s) in the case (ii), and to deduce therefrom the height of the at least one tread pattern element during the rolling of the tire. For example, the acquisition module can also be designed to emit signals representative of the capacitance or resistance values towards a central unit mounted inside a vehicle fitted with the tire. According to a variant embodiment of the invention, the acquisition module is also designed to be remotely energized by an interrogation circuit mounted on the wheel or on a fixed part of the vehicle adjacent to the wheel, and to cooperate by coupling with an inductance provided within the tread so as to transmit to the interrogation circuit the capacitance measurement acquired by the module. A tire according to the invention is such that it comprises a tread such as that described above. According to an example embodiment of the invention, the tire is such that its tread comprises, as the pattern element according to the invention, a circumferential “rib” or ridge extending all round the circumference of the tread. According to another example embodiment of the invention, the tire is such that its tread comprises, as the pattern element according to the invention, an element consisting of a “wear indicator”, i.e. an element for example in the form of a block or ridge whose height is substantially less than that of the other tread pattern elements. A further purpose of the present invention is to propose a mounted assembly for an automobile vehicle comprising a tire and a wheel on which the tire is fitted, the tire comprising a tread having pattern elements each with a base and a crown connected to one another by at least one lateral face and which define the height of the element, the crown being intended, when the tire is rolling on a rolling surface, to be in contact at one time or another with the surface, at least one of the tread pattern elements of the tire having n conducting layers face to face with one another and of the same height (n being an integer≧2) and n−1 insulating layer(s), which consist respectively of electrically conducting layers and insulating layer(s) of rubber, such that two adjacent conducting layers are separated from one another by an insulating layer which extends to the height of the conducting layers in a direction normal to that of the crown, in such manner that the element defines a capacitor whose capacitance value is representative of the momentary height of the element. According to a “passive” embodiment of the invention (passive components in the tire), this mounted assembly is such that the tread has in its mass a resonance circuit one of whose elements is the capacitor. The resonance circuit is such that its resonance frequency is a function of the capacitance of the capacitor. For example, the resonance circuit comprises an inductance mounted under the tread pattern element, and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit which is attached permanently to the wheel and is provided with a frequency-scanning energy generator and means of detection provided to detect the frequency at which the circuits are in tune, so as to deduce from this tuned frequency the capacitance value of the capacitor and to deduce from that value the height of the tread pattern element. The interrogation circuit can for example comprise a frequency-scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit and a resistance, and the means for detecting the tuning frequency are for example mounted at the terminals of the resistance to measure the voltage between those terminals. According to another, “active” embodiment of the invention (active components in the tire, in contrast to the “passive” mode), the mounted assembly is such that the tire tread has in its mass, on the one hand an acquisition module designed to measure the capacitance value and which is remotely energized by an interrogation circuit mounted on the wheel, and on the other hand an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit comprising means for deducing the height of the tread pattern element from the capacitance value. Note that in accordance with these two embodiments, the interrogation circuit can for example be mounted on the valve fitted to the wheel (and in this case one speaks of an instrumented valve), on a module for measuring the internal pressure of the tire that can be fitted to the wheel, more generally on an existing device mounted on the wheel, or even at a given location in the surface over which the wheel rolls. A further aspect of the present invention is an automobile vehicle provided with tires whose respective treads each comprise tread pattern elements, each element comprising a base and a crown connected to one another by at least one lateral face which defines the height of the element, the crown being intended, when the tire is rolling on a rolling surface, to be in contact with the ground at one time or another, and the vehicle comprising means for continuously measuring the wear of at least one of the tires, such means not including any electrically active component at all in the tire, at least one tread pattern element of at least one of the tires comprising n conducting layers face to face and of the same height (n being an integer≧2) and n−1 insulating layer(s) which consist respectively of electrically conducting layers and insulating layer(s) of rubber, two adjacent conducting layers being separated from one another by an insulating layer which covers them entirely in a direction normal to the crown, in such manner that the element defines a capacitor whose capacitance value is representative of the height of the element. According to an embodiment of the invention, the vehicle is such that the tread of the at least one tire has in its mass a resonance circuit comprising an inductance mounted underneath the tread pattern element and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit attached to a fixed part of the vehicle close to the tire, and the interrogation circuit is provided with a frequency-scanning energy generator and with detection means to detect the in-tune frequency between the circuits, in order to deduce from that tuned frequency the capacitance value of the capacitor and, from that capacitance value, to deduce the height of the pattern element, the interrogation circuit also being designed to communicate with a central unit provided in the cockpit of the vehicle. Note that this tire has in its mass only electrically passive components. According to an example embodiment of the invention, the interrogation circuit comprises a frequency-scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit, and a resistance, and the resonance frequency detection means are mounted for example at the terminals of the resistance to measure the voltage between those terminals. According to another embodiment of the invention, the vehicle is such that the tread of the at least one tire has in its mass, on the one hand an acquisition module designed to measure the capacitance value and which is remotely energized by an interrogation circuit attached to a fixed part of the vehicle adjacent to the tire, and on the other hand an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit having means for deducing the height of the tread pattern element from this capacitance value, and the interrogation circuit also being able to communicate with a central unit provided in the cockpit of the vehicle. The aforesaid characteristics of the present invention, and others, will be better understood on reading the following description of an example embodiment of the invention, which is given for illustrative and non-limiting purposes, the description relating to the attached drawings which show: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, perspective view of a tread pattern element according to a first example of a first embodiment of the invention FIG. 2 is a schematic, perspective view of a tread pattern element according to a second example of the first embodiment of the invention; FIG. 3 is a schematic, perspective view of a tread pattern element according to a second embodiment of the invention; FIG. 4 is a schematic, perspective view of a tread pattern element according to a third example of the first embodiment of the invention; FIG. 5 is a schematic, perspective view of a tread pattern element according to a third embodiment of the invention; FIG. 6 is an experimental graph illustrating, for four tread pattern elements having the same geometry (represented in the medallion) identical to that of FIG. 1 and centered on the same circumferential plane of a tire, the relation between the height of each of the four pattern elements and the capacitance of the capacitor constituted by that element; FIG. 7 is an experimental graph illustrating, for four other tread pattern elements having the same geometry (represented in the medallion) identical to that of FIG. 4 and centered on the same circumferential plane of a tire, the relation between the height of each of the four pattern elements and the capacitance of the capacitor constituted by that element; and FIG. 8 is a schematic, perspective view of a system according to an example embodiment of the invention, for determining the height of a tread pattern element. DETAILED DESCRIPTION In this example, the tread pattern element 1 in FIG. 1 has a parallelepiped shape. It is delimited by a base 2, a crown 3 intended to evolve against the ground during the rolling of a tire whose tread comprises such an element 1, and lateral faces 4 which connect the crown 3 to the base 2. This tread pattern element 1 consists of two electrically conducting layers 5a and 5b which are identical and of rectangular shape (of height H and width L), which are applied against an electrically insulating layer 6 (of thickness e) so that the layers 5a, 5b and 6 are face to face with one another and each extends in height from a level with the base 2 at one end, to a level with the crown 3 at the opposite end. As can be seen in FIG. 1, this stack of layers 5a, 5b and 6 forms a capacitor whose armature plates and dielectric consist respectively of the conducting layers 5a and 5b and of the insulating layer 6. The capacitance of this capacitor is given by the formula: C = ɛ 0 ɛ r LH e ( 1 ) where εo is the permittivity of a vacuum and εr is the relative permittivity of the dielectric. It follows that the height H of the tread pattern elements of a rolling tire can be determined from the value of the corresponding capacitor's capacitance, that capacitance being measurable for example by an electric acquisition module connected to the element 1 under the latter, within the tread. The acquisition module can be adapted to emit signals representative of these capacitance measurements, towards a central unit mounted inside the vehicle equipped with the tire and designed to inform the driver continuously about the wear of the tread pattern elements 1. Tests carried out on tires four tread pattern elements 1 of which, aligned in the circumferential direction, have the capacitor structure described in relation to FIG. 1, satisfactorily confirm this relation of proportionality between the height H (in mm) and the capacitance C (expressed in arbitrary units), as shown by the graph of FIG. 6 in which the four “bunches” of points obtained correspond to these four tread pattern elements 1. The tread pattern element 1 of the tire represented in a medallion in FIG. 6, which is of parallelepiped shape, has an initial height Hi of 8 mm, a width of 20 mm, a depth of 20 mm and an insulating layer 6 of thickness e equal to 2 mm. The composition of the rubber used in each of the four tread pattern elements 1 for the insulating layer 6 is of the type used in the treads of the “MXT ENERGY” brand tires, i.e. having a resistivity between 1012 and 1015 Ω.cm. This composition is based on a blend of a styrene/butadiene copolymer prepared in solution (S-SBR) and a polybutadiene (BR), and comprises 80 phr of “ZEOSIL 1165 MP” silica as the reinforcing filler. The rubber composition used for the conducting layers 5a and 5b has a resistivity close to 108 Ω.cm, and is based on a S-SBR/BR blend containing 60 phr of “N234” carbon black as the reinforcing filler. The curve represents the results obtained for the wear of the tire. The direction of the wear has been indicated by the arrow U. For the description of the next figures, the numerical indexes used have been increased by 10 to identify elements whose structure or function are analogous to the elements described earlier in relation to FIG. 1. The tread pattern element 11 of FIG. 2 differs from the element 1 of FIG. 1 only in that it consists of three electrically conducting layers 15a, 15b and 15c, which are identical and of rectangular shape (of height H and width L), with two electrically insulating layers 16a and 16b (of respective thickness e1 and e2) respectively applied, on the one hand between the conducting layers 15a and 15b, and on the other hand between the conducting layers 15b and 15c. These layers 15a, 16a, 15b, 16b, 15c are again face to face with one another and extend in height from a level with the base 12 at one end to a level with the crown 13 at the opposite end, so that the stack forms two capacitors arranged in series, whose armature plates and dielectrics consist respectively of two adjacent conducting layers 15a and 15b or 15b and 15c, and of the insulating layers 16a or 16b. The total capacitance C of the capacitors is given by the formula: C = ɛ 0 ɛ r LH e 1 + e 2 ( 2 ) As before, it follows that the height H of the tread pattern elements 11 of a rolling tire can be determined at any time from the total capacitance value of the corresponding capacitors, that capacitance being measurable for example by an electronic acquisition module connected to the capacitor formed by the element 11 underneath the latter, inside the tread. This acquisition module can be designed to emit signals representative of the capacitance measurements towards a central unit inside the vehicle, which is intended to inform the driver continuously about the wear of the elements 11. The tread pattern element 21 of FIG. 3 has in this example a cylindrical shape, delimited by a base 22, a crown 23 and lateral faces 24, in the manner of the element 1 of FIG. 1. This tread pattern element 21 consists of cylindrical and coaxial layers 25a, 25b, 26 (having the same height H), which comprise two electrically conducting layers 25a and 25b between which is applied an electrically insulating layer 26, such that these layers 25a, 25b and 26 are face to face with one another and each extend in height from a level with the base 22 at one end to a level with the crown 23 at the opposite end. The radially internal conducting layer 25a and the insulating layer 26 have radii R1 and R2 respectively (and consequently, the insulating layer 26 has thickness equal to R2-R1). As can be seen from FIG. 3, this stack of layers 25a, 25b, 26 forms a capacitor, whose armature plates and dielectric consist respectively of the conducting layers 25a and 25b, and of the insulating layer 26. The capacitance C of this capacitor is given by the formula: C = 2 π ɛ 0 ɛ r H Log ( R 2 R 1 ) ( 3 ) As before, it follows that the height of the tread pattern elements 21 of a rolling tire can be determined at any time, from the capacitance value of the corresponding capacitor, which can for example be measured by an electronic acquisition module connected to the capacitor formed by the element 21 underneath the latter, inside the tread. The acquisition model can be designed to emit signals representative of these capacitance measurements towards a central unit inside the vehicle, which is intended to inform the driver continuously about the wear of the elements 21. In the example of FIG. 4, the tread pattern element 31 has a parallelepiped shape, delimited by a base 32, a crown 33 and lateral faces 34. This tread pattern element 31 comprises two electrically conducting layers 35a and 35b, which are identical and of rectangular shape (of width L), which are applied against an electrically insulating layer (of thickness e and height Ho) such that the layers 35a, 35b and 36 are face to face with one another and are at a first end on a common level with the base 32 of the element 31. As can be seen in FIG. 4, the insulating layer 36 only partially covers each of the conducting layers 35a and 35b, so that the conducting layers are connected to one another by a third, intermediate conducting layer 35c (also of thickness e) which extends the insulating layer 36 by a height H towards the crown 33 of the element 31, the three conducting layers 35a, 35b, 35c each having an upper end on a common level with the crown 33. It follows from the presence of the intermediate conducting layer 35c and the insulating layer 36 between the conducting layers 35a and 35b, that the element 31 forms an electrical resistance whose value satisfies, to the first order, the formula: R = ρ e LH ( 4 ) where p is the resistivity of the conducting layer 35c. By defining the tread pattern element 31 as presenting a height, relative to the immediately adjacent surfaces of the tire tread (these reference surfaces are represented in FIG. 4 by broken lines), which is equal to the height H of the intermediate conducting layer 35c, it follows from formula (4) that the height H of the tread pattern elements 31 of a rolling tire can be determined at any time for the value of the corresponding resistance, the resistance being measurable for example by an electronic acquisition model connected to the resistance formed by the element 31 underneath the latter, inside the tread. This acquisition module can be designed to emit signals representative of these resistance measurements towards a central unit inside the vehicle, which is intended to inform the driver continuously about the wear of the elements 31. Note that the wear of the tread pattern element 31 that corresponds to zero value of the height H of the intermediate conducting layer 35c (i.e. the relative height of this element 31), is reached for a theoretically infinite (in practice very high) value of the resistance R, and is then equivalent to a capacitor capacitance. Tests carried out on tires, four tread pattern elements 31 of which, aligned in the circumferential direction, have the resistance structure described above in relation to FIG. 4, satisfactorily confirm this relation of proportionality between the relative height H and the resistance R, as shown by the graph of FIG. 7 in which the four “bunches” of points obtained correspond to the four tread pattern elements 31. In this graph of FIG. 7, the resistance R is measured as a function of the total height Ho+H (the pattern element 31 has an initial relative height Hi of 5 mm and an insulating layer 36 of thickness e equal to 2 mm and height Ho equal to 3 mm). The wear direction is indicated by the arrow U. The rubber composition used in this tread pattern element 31 for the insulating layer 36 is of the tire used in the tread of the “MXT ENERGY” brand tires, i.e. its resistivity is between 1012 and 1015 Ω.cm. This composition is based on a S-SBR/BR blend and it contains 80 phr of “ZEOSIL 1165 MP” silica as the reinforcing filler. The rubber composition for the conducting layers 25a, 35b and 35c has a resistivity close to 108 Ω.cm, is based on a S-SBR/BR blend, and contains 60 phr of “N234”0 carbon black as the reinforcing filler. The tread pattern element 41 of FIG. 5 has in this example a parallelepiped shape delimited by a base 42, a crown 43 and lateral faces 44. This tread pattern element 41, of height H and width L, consists of an electrically insulating rubber composition 46 in which are embedded two identical wires 45a and 45b (shown as dotted lines in FIG. 5) parallel to one another and electrically conducting, so as to form a capacitor whose dielectric and armature plates are formed respectively by the insulating composition 46 and the wires 45a and 45b. The wires 45a and 45b are positioned a distance e apart and each wire has the same diameter D and the same height H, such that they extend from a level with the base 42 at one end to a level with the crown 43 of the element 41 at an opposite end. The capacitance C of this capacitor is given by the formula: C = π ɛ 0 ɛ r H Arcch ( e D ) ( 5 ) in which Arcch is the argument function of the hyperbolic cosine. As before, it follows that the height H of the tread pattern elements H of a rolling tire can be determined at any time from the capacitance value of the corresponding capacitor, which capacitance can be measured for example by an electronic acquisition module connected to the capacitor formed by the element 41 underneath the latter, inside the tread. The acquisition module can be designed to emit signals representative of these capacitance measurements towards a central unit inside the vehicle, which is intended to inform the driver continuously about the wear of the elements 41. FIG. 8 illustrates an example embodiment according to the invention of a system 50 for the continuous measurement in real time of the wear of a tire tread 60 during rolling, the system 50 being designed for fitting in an automobile vehicle. The tread 60, which is shown partially and in perspective in FIG. 8, comprises a plurality of tread pattern elements 61 at least one of which confirms to the present invention and forms a capacitor whose capacitance value C is proportional to the height of the element 61. The capacitor 61 can for example be of the type described with reference to any of FIGS. 1, 2 or 3 (in the example of FIG. 8 it is a capacitor according to FIG. 1). It is understood that several, or even all the tread pattern elements 61 of the tread 60 could consist of such capacitors according to the invention. The measurement system 50 comprises on the one hand an interrogation circuit 70 (or primary circuit), and on the other hand a resonance circuit 80 (or secondary circuit) coupled electromagnetically to the primary circuit and located in the tread 60. The interrogation circuit 70 is mounted permanently on a fixed part of the vehicle (not shown), such as the mudguard adjacent to the tire, or else it can be mounted on the wheel itself, for example on the valve or on an internal pressure measurement module with which the wheel is provided. In this example embodiment, the interrogation circuit 70 comprises a frequency scanning energy generator 71, a resistance 72, a capacitor 73, and an antenna 74 formed by an inductance. Note that this circuit 70 could have no resistance 72, i.e. it could consist of a capacitor 73 associated with an inductance 74. The resonance circuit 80, which is electrically passive, is an “LC” circuit comprising an antenna 81 formed by an inductance connected to the armature plates 65a and 65b of the capacitor formed by the tread pattern element 61. This inductance 81 is located under the element 61, inside the tread 60, and is coupled (see arrow C) to the inductance 74 of the circuit 70. The interrogation circuit 70 is provided with means 75 for detecting the in-tune frequencies fo (also known as resonance frequencies fr) between the resonance circuit 80 and the interrogation circuit 70. The detection means 75 are connected across the terminals of the resistance 72 and is for example designed to measure the voltage amplitude across those terminals, which passes through an optimum (energy absorption) when there is a frequency match fo between the two circuits. The system 50 operates as follows to measure the height H of the tread pattern element 61. The energizing frequency of the generator 71 is varied continuously, and the voltage across the terminals of the resistance 72 is measured to determine the frequency fo at which the resonance circuit 80 is tuned to the interrogation circuit coupled to it. From this value fo, the value of the capacitance C of the capacitor formed by the element 61 is deduced, using the equation linking the tuned frequency fo (or tuned pulsation ωo) and the capacitance C: {overscore (ω)}o2LC=1 (L being the self-induction coefficient of the inductance 81), so that if {overscore (ω)}=2πƒo: (2πƒo)2LC=1. From this, the aforesaid height H is deduced using one or other of the aforesaid formulas (1), (2) or (3) given with reference to FIGS. 1, 2 and 3. Note that the system 50 for measuring the height H of the tread pattern element 61 is designed to measure indirectly the capacitance C of the capacitor formed by the element 61 (via the tuned frequency fo), in contrast to the aforesaid acquisition module mentioned in relation to FIGS. 1, 2, 3 and 5, which measures the capacitance directly. Moreover, this system 50 has an advantage in that it comprises only one, passive electrical circuit within the tire, since the wear is detected remotely (whether on a fixed part of the vehicle, or on the wheel). The method and devices according to the invention have the decisive advantage of indicating the wear of a tire at all times. Of course, it is not necessary to effect this wear measurement all the time, but at various time intervals. The invention has been described in terms of preferred principles, embodiments, and structures for the purposes of description and illustration. Those skilled in the art will understand that substitutions may be made and equivalents found without departing from the scope of the invention as defined by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention concerns a method for the continuous measurement of the wear of a tire. The invention also concerns an element of a tread pattern for a tire which is provided with means to enable continuous measurement of the wear of the element during the rolling of the tire over a rolling surface, a tread comprising the element, and a tire comprising the tread. The invention also concerns a fitted assembly for an automobile vehicle, and such a vehicle which comprises means for measuring the wear of the tire continuously and in real time. It is known to provide devices for detecting wear of the tread patterns of tires for automobile vehicles. German Patent DE-A-197 45 734 (see FIGS. 2 and 3 thereof) discloses a tire whose tread comprises in its mass a plurality of metallic wires which form electrically conducting loops that extend respectively to different heights within a pattern rib of the tread, and which are connected to a detection circuit underneath the rib. During the rolling of a vehicle fitted with this tire, these loops are broken one after the other to form open switches and the detection circuit delivers a signal representative of these breaks to an evaluation unit present in the vehicle. A major disadvantage of this wear detector is that the wear is detected discontinuously because it is a function of the number of loops successively broken (i.e. the number of open switches). Another disadvantage of this wear detector is that it seems very difficult for a person engaged in the field to manufacture it in a precise manner. In the context of the present description, the “fixed part” of a vehicle will be understood as the chassis of the vehicle and the suspension rods, as opposed to the “rotating parts” which include the wheels, tires and hubs. | <SOH> SUMMARY OF THE INVENTION <EOH>One aspect of the present invention is a method for the continuous measurement of the wear of a tire, i.e., one which enables the wear to be measured at any time, whether during rolling of a vehicle fitted with the tire, or else when the vehicle is at rest. According to the invention, this method consists in measuring the capacitance or electrical resistance inside a tread pattern element of the tire, and deducing the height of the element by virtue of an equation relating the capacitance or resistance to the height. Preferably, the process consists in using as the tread pattern element an element formed such that its capacitance or resistance is directly proportional to the height of the element. In other words, the height is a linear function of the capacitance or resistance. Consequently, the acquisition module does not require a complex algorithm (linear transfer function) to measure the height of the tread pattern element. In this description “tread pattern element” means any relief element of the tire tread which is intended to be in contact with the rolling surface at any time (i.e. from when rolling begins, or after wear of the element has started). Thus, the element can consist of a block of substantially parallelepiped or cylindrical shape, or a “rib” or circumferential ridge whose cross-section varies (i.e. extending over all or part of the circumference of the tread). According to one example embodiment of the invention, the method consists in effecting the capacitance or resistance measurement by providing within the tire an electronic acquisition module which is connected to the tread pattern element underneath the tread. According to a first embodiment of the invention in which the tire is mounted on a wheel and fitted to an automobile vehicle, the method consists essentially in effecting a capacitance measurement relating to the pattern element, by determining the tuning frequency of a passive resonance circuit comprising at least one capacitor formed by the pattern element and an inductance connected to the capacitor in the tread of the tire, by means of an interrogation circuit mounted on the wheel or on a fixed part of the vehicle that is adjacent to the wheel. According to a second embodiment of the invention in which the tire is again mounted on a wheel and fitted on an automobile vehicle, the method consists in effecting a capacitance measurement relating to the tread pattern by remote energizing of the acquisition module via an interrogation circuit mounted on the wheel or on a fixed part of the vehicle that is adjacent to the wheel, and transmitting to the interrogation circuit the capacitance measurement acquired by the module via an inductance coupled within the tire to the acquisition module. According to a first example embodiment of the invention, the method consists in measuring the capacitance within the tread pattern element, by providing that at least one capacitor is formed in the element. A capacitor in accordance with the invention can consist of electrically conducting plates forming armatures separated from one another by an electrically insulating rubber composition which forms a dielectric for the capacitor. Each of these plates can be metallic, consisting for example of copper or brass or another metal compatible with the rubber used, or it can consist of an electrically conducting rubber composition, for example one containing a sufficient quantity of carbon black as the reinforcing filler. A capacitor can alternatively consist of metallic wires, for example of copper or brass. Note that the use of a capacitor in the tread pattern element enables the energy consumed to be minimized, since the reactive power characterizes the capacitor. This energy consumption can advantageously be minimized by interrogating the acquisition module when the vehicle is stopped (for example, each time it is started, by inserting the ignition key), by means of a central unit mounted inside the vehicle. According to a second example embodiment of the invention, the method consists in measuring the resistance in the tread pattern element, by providing that at least one electrical resistance is formed in the element. As before, the resistance can comprise electrically conducting plates (metallic, or of electrically conducting rubber) or else metallic wires such as those mentioned earlier. Preferably, the plates mentioned above in relation to the capacitor or resistance are flat; however, other shapes or contours are possible. Another purpose of this invention is to propose a tread pattern element for a tire, the element comprising a base and a crown connected to one another by at least one lateral face which defines the height of the element, the crown being intended, when the tire is rolling over a rolling surface, to be in contact with the ground at one time or another, and such that in relation to an acquisition module to which it is connected, the structure of the element makes it possible to measure the wear of the tread continuously. To that end, a tread pattern element according to the invention comprises n conducting layers face to face with one another and of the same height ( n being an integer≧2) and n −1 insulating layer(s) which consist respectively of electrically conducting and insulating rubber compositions, two adjacent conducting layers being separated from one another by an insulating layer which extends a complete height of the conducting layers (case (i)) or part of the height of the conducting layers (case (ii)) in a direction normal to that of the crown, such that the element defines at least one capacitor in the case (i) or at least one electrical resistance in the case (ii), which respectively have a capacitance C or resistance R value representative of the height of the element. It follows that the height of the tread pattern element can be determined at any time during rolling from the value of the capacitance of the capacitor(s) or resistance(s) that it forms, this capacitance or resistance value being measurable by an electronic acquisition module which is connected to the tread pattern element underneath the latter, inside the tread. Note that in the case where the pattern element consists of a circumferential “rib” or ridge of given cross-section, the aforesaid conducting or insulating layers extend over the full circumference of the tread. Note also that the capacitors or resistors formed in such tread pattern elements advantageously consist of the rubber compositions customarily used for making tire treads, which facilitates the fabrication of the treads and so minimizes their cost. Furthermore, when the capacitor or resistor is made of rubber, this imparts better cohesion to the tread of the corresponding tire (compared with the cohesion between metallic parts and rubber parts). The improved cohesion results in performances of the tire, such as wear or grip, which are not appreciably degraded during rolling. According to an example embodiment of the invention, the conducting layers are positioned with one end on a level with the crown, and each insulating layer has one end on a level with the crown in the case (i) capacitor or the one end a distance away from the crown in the case (ii) resistor. As a result, the wear of the tread pattern element can be measured continuously from the beginning of rolling, for a tread pattern element in contact with the rolling surface from the time rolling begins. The conducting layers on the one hand, and the at least one insulating layer on the other hand, have a radially-inner end on a level with the base. According to a first embodiment of the invention, the conducting layers and insulating layer(s) are rectangular and are stacked over one another so as to impart a parallelepiped shape to the element. A tread pattern element according to this embodiment of the invention can form a capacitor, if it consists of two electrically conducting layers of rectangular shape (whether parallel or not) applied against an electrically insulating layer such that the three layers are face to face and all three have a first end on a level with the base, and a second, opposite end on a level with the crown. The armature plates and the dielectric of the capacitor consist respectively of the conducting layers and the insulating layer. As a variant, a tread pattern element according to the invention can form several capacitors in series, for example comprising three electrically conducting layers which are identical and of rectangular shape, with two electrically insulating layers applied respectively between a first and a second pair of adjacent conducting layers. All these layers are again face to face with one another with a first end on a level with the base on the one hand and a second opposite end on a level with the crown on the other hand. The armature plates and the dielectric of this capacitor consist respectively of the conducting layers and the insulating layers. A tread pattern element according to the invention can also form a resistance, comprising two identical and rectangular electrically conducting layers applied on an electrically insulating layer, such that the layers are face to face with one another and all three have a first end on a level with the base of the tread pattern element. The insulating layer only partially extends the height of the conducting layers, so that the conducting layers are connected to one another by a third, median conducting layer which extends the insulating layer to a given height (representing the height of the wear to be measured) in the direction of the crown of the tread pattern element, the three conducting layers having radially outer ends on a level with the crown. In a second embodiment according to the invention, the conducting and insulating layer(s) are concentric and are positioned one inside the other, whether or not they are closed upon themselves. For example, the layers can be cylindrical and positioned coaxially against one another, so as to confer upon the element the geometry of a solid cylinder or part-cylinder. A tread pattern element according to this variant of the invention can for example form a capacitor, and consists of cylindrical and coaxial layers of the same height comprising two electrically conducting layers between which is applied an electrically insulating layer, such that these layers are face to face and having a first end on a level with the base and a second opposite end on a level with the crown. The armature plates and the dielectric of this capacitor consist respectively of the conducting layers and the insulating layer. According to another aspect of the invention, the element consists of an electrically insulating rubber composition in which are embedded at least two identical, electrically conducting wires parallel to one another, so as to form at least one capacitor (a single capacitor, or several capacitors arranged in series) whose dielectric and armature plates are formed respectively by the insulating composition and the wires, the capacitor having a capacitance value at any moment which is representative of the height of the element at that moment. According to an example embodiment of the invention, the wires have a first end on a level with the base, and an opposite end on a level with the crown. It follows that the height of this tread pattern element can be determined during rolling, from the capacitance value of the capacitor(s) that it forms, this capacitance being measured by an electronic acquisition module connected to the tread pattern element under the latter, within the tread. A tread of a tire according to the invention is such that it comprises at least one tread pattern element such as one of those described above. Note that when the tread pattern element consists of a capacitor or resistance formed of the conducting layers and insulating layer(s) of rubber and if the composition of the tread or the tread underlayer has a reduced resistivity (for example, similar to that of the conducting layers), then the tread or its underlayer must necessarily also comprise an insulating layer arranged radially underneath the tread pattern element so as to cover its base entirely, whose purpose is to insulate the tread pattern element electrically from the tread or underlayer composition. This insulating layer, whose thickness is advantageously small, can for example consist of a rubber composition whose resistivity is analogous to that of the at least one insulating layer of the capacitor or resistance forming the tread pattern element (i.e. with resistivity for example between 10 12 and 10 15 Ω.cm). According to another characteristic of the invention, the tread comprises in its mass an electronic acquisition module which is connected to the at least one element underneath the latter and is designed to measure the value of the capacitance or resistance of the capacitor(s) in the case (i) or of the resistance(s) in the case (ii), and to deduce therefrom the height of the at least one tread pattern element during the rolling of the tire. For example, the acquisition module can also be designed to emit signals representative of the capacitance or resistance values towards a central unit mounted inside a vehicle fitted with the tire. According to a variant embodiment of the invention, the acquisition module is also designed to be remotely energized by an interrogation circuit mounted on the wheel or on a fixed part of the vehicle adjacent to the wheel, and to cooperate by coupling with an inductance provided within the tread so as to transmit to the interrogation circuit the capacitance measurement acquired by the module. A tire according to the invention is such that it comprises a tread such as that described above. According to an example embodiment of the invention, the tire is such that its tread comprises, as the pattern element according to the invention, a circumferential “rib” or ridge extending all round the circumference of the tread. According to another example embodiment of the invention, the tire is such that its tread comprises, as the pattern element according to the invention, an element consisting of a “wear indicator”, i.e. an element for example in the form of a block or ridge whose height is substantially less than that of the other tread pattern elements. A further purpose of the present invention is to propose a mounted assembly for an automobile vehicle comprising a tire and a wheel on which the tire is fitted, the tire comprising a tread having pattern elements each with a base and a crown connected to one another by at least one lateral face and which define the height of the element, the crown being intended, when the tire is rolling on a rolling surface, to be in contact at one time or another with the surface, at least one of the tread pattern elements of the tire having n conducting layers face to face with one another and of the same height ( n being an integer≧2) and n −1 insulating layer(s), which consist respectively of electrically conducting layers and insulating layer(s) of rubber, such that two adjacent conducting layers are separated from one another by an insulating layer which extends to the height of the conducting layers in a direction normal to that of the crown, in such manner that the element defines a capacitor whose capacitance value is representative of the momentary height of the element. According to a “passive” embodiment of the invention (passive components in the tire), this mounted assembly is such that the tread has in its mass a resonance circuit one of whose elements is the capacitor. The resonance circuit is such that its resonance frequency is a function of the capacitance of the capacitor. For example, the resonance circuit comprises an inductance mounted under the tread pattern element, and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit which is attached permanently to the wheel and is provided with a frequency-scanning energy generator and means of detection provided to detect the frequency at which the circuits are in tune, so as to deduce from this tuned frequency the capacitance value of the capacitor and to deduce from that value the height of the tread pattern element. The interrogation circuit can for example comprise a frequency-scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit and a resistance, and the means for detecting the tuning frequency are for example mounted at the terminals of the resistance to measure the voltage between those terminals. According to another, “active” embodiment of the invention (active components in the tire, in contrast to the “passive” mode), the mounted assembly is such that the tire tread has in its mass, on the one hand an acquisition module designed to measure the capacitance value and which is remotely energized by an interrogation circuit mounted on the wheel, and on the other hand an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit comprising means for deducing the height of the tread pattern element from the capacitance value. Note that in accordance with these two embodiments, the interrogation circuit can for example be mounted on the valve fitted to the wheel (and in this case one speaks of an instrumented valve), on a module for measuring the internal pressure of the tire that can be fitted to the wheel, more generally on an existing device mounted on the wheel, or even at a given location in the surface over which the wheel rolls. A further aspect of the present invention is an automobile vehicle provided with tires whose respective treads each comprise tread pattern elements, each element comprising a base and a crown connected to one another by at least one lateral face which defines the height of the element, the crown being intended, when the tire is rolling on a rolling surface, to be in contact with the ground at one time or another, and the vehicle comprising means for continuously measuring the wear of at least one of the tires, such means not including any electrically active component at all in the tire, at least one tread pattern element of at least one of the tires comprising n conducting layers face to face and of the same height ( n being an integer≧2) and n −1 insulating layer(s) which consist respectively of electrically conducting layers and insulating layer(s) of rubber, two adjacent conducting layers being separated from one another by an insulating layer which covers them entirely in a direction normal to the crown, in such manner that the element defines a capacitor whose capacitance value is representative of the height of the element. According to an embodiment of the invention, the vehicle is such that the tread of the at least one tire has in its mass a resonance circuit comprising an inductance mounted underneath the tread pattern element and the capacitor to whose armature plates the inductance is connected, the resonance circuit being coupled to an interrogation circuit attached to a fixed part of the vehicle close to the tire, and the interrogation circuit is provided with a frequency-scanning energy generator and with detection means to detect the in-tune frequency between the circuits, in order to deduce from that tuned frequency the capacitance value of the capacitor and, from that capacitance value, to deduce the height of the pattern element, the interrogation circuit also being designed to communicate with a central unit provided in the cockpit of the vehicle. Note that this tire has in its mass only electrically passive components. According to an example embodiment of the invention, the interrogation circuit comprises a frequency-scanning energy generator, a capacitor, an inductance coupled to the inductance of the resonance circuit, and a resistance, and the resonance frequency detection means are mounted for example at the terminals of the resistance to measure the voltage between those terminals. According to another embodiment of the invention, the vehicle is such that the tread of the at least one tire has in its mass, on the one hand an acquisition module designed to measure the capacitance value and which is remotely energized by an interrogation circuit attached to a fixed part of the vehicle adjacent to the tire, and on the other hand an inductance coupled to the acquisition module to transmit to the interrogation circuit the capacitance measurement acquired by the module, the interrogation circuit having means for deducing the height of the tread pattern element from this capacitance value, and the interrogation circuit also being able to communicate with a central unit provided in the cockpit of the vehicle. The aforesaid characteristics of the present invention, and others, will be better understood on reading the following description of an example embodiment of the invention, which is given for illustrative and non-limiting purposes, the description relating to the attached drawings which show: | 20040331 | 20080729 | 20050127 | 72051.0 | 0 | ALLEN, ANDRE J | METHOD AND DEVICE FOR THE CONTINUOUS MEASUREMENT OF THE WEAR OF A TIRE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,488 | ACCEPTED | CONTROLLED PRESSURE FUEL NOZZLE INJECTOR | A multi-staged gas turbine engine fuel supply fuel injector includes at least first and second staged fuel injection circuits having first and second fuel injection points. At least first and second fuel nozzle valves operable to open at different first and second crack open pressures are controllably connected to the first and second staged fuel injection circuits, respectively. A single fuel supply manifold is connected to all of the fuel nozzle valves. A single fuel signal manifold is controllably connected to all of the first and second fuel nozzle valves. The fuel injector includes a valve housing containing the fuel nozzle valves. | 1. A fuel injector comprising: a valve housing, a hollow stem depending from the housing, at least one fuel nozzle assembly supported by the stem, at least first and second staged fuel injection circuits in the fuel injector, each of the first and second staged fuel injection circuits having first and second fuel injection points, at least first and second fuel nozzle valves controllably connected to the first and second staged fuel injection circuits respectively, the first and second fuel nozzle valves being operable to open at different first and second crack open pressures respectively, the housing including a single fuel supply connector connected in fuel supply relationship with the first and second fuel nozzle valves and a single fuel signal connector connected in pressure supply relationship with the first and second fuel nozzle valves, and the housing including a single fuel supply connector connected in fuel supply relationship with the first and second fuel nozzle valves and a single fuel signal connector connected in pressure supply relationship with the first and second fuel nozzle valves. 2. A fuel injector as claimed in claim 1 further comprising the first injection point of the first staged fuel injection circuit being a tip orifice in a fuel injector tip of a pilot nozzle of the fuel injector and the second fuel injection points of the second staged fuel injection circuits located in a main nozzle of each of the fuel injectors. 3. A fuel injector as claimed in claim 2 wherein the main nozzle is annular and has radially extending spray orifices located at the second staged fuel injection circuits. 4. A fuel injector as claimed in claim 3 further comprising: internal fuel flow passages of the first and second staged fuel injection circuits extending through the annular main nozzle, clockwise and counterclockwise extending annular legs extending circumferentially from at least a first one of the internal fuel flow passages through the main nozzle, and the first injection points of the first staged fuel injection circuits located at spray orifices extending from the annular legs through at least one of the plates. 5. A fuel injector as claimed in claim 4 wherein the annular legs have waves. 6. A fuel injector as claimed in claim 5 wherein the waves are parallel. 7. A fuel injector as claimed in claim 6 wherein the spray orifices are located in alternating ones of the first and second waves so as to be substantially aligned along a circle. 8. A fuel injector as claimed in claim 2 further comprising: the first and second staged fuel injection circuits extending at least in part through a fuel injector conduit, the fuel injector conduit extending between the housing through the stem to the nozzle assembly, the fuel injector conduit comprising at least one feed strip having at least one bonded together pair of lengthwise extending plates, each of the plates having widthwise spaced apart and lengthwise extending parallel grooves, and the plates being bonded together such that opposing grooves in each of the plates are aligned forming internal fuel flow passages of the first and second staged fuel injection circuits through the length of the strip from an inlet end to an outlet end. 9. A fuel injector as claimed in claim 8 further comprising: the internal fuel flow passages extending through the feed strip and the annular main nozzle, clockwise and counterclockwise extending annular legs extending circumferentially from at least a first one of the internal fuel flow passages through the main nozzle, and the first injection points of the first staged fuel injection circuits located at spray orifices extending from the annular legs through at least one of the plates. 10. A fuel injector as claimed in claim 9 wherein the annular legs have waves. 11. A fuel injector as claimed in claim 10 wherein the waves are parallel. 12. A fuel injector as claimed in claim 11 wherein the spray orifices are located in alternating ones of the first and second waves so as to be substantially aligned along a circle. 13. A fuel injector comprising: a valve housing, a hollow stem depending from the housing, at least one fuel nozzle assembly supported by the stem, first, second, and third staged fuel injection circuits in the fuel injector, the first, second, and third staged fuel injection circuits extending at least in part through a fuel injector conduit, the fuel injector conduit extending between the housing through the stem to the nozzle assembly, each of the first, second, and third staged fuel injection circuits having first, second, and third fuel injection points, first, second, and third fuel nozzle valves controllably connected to the first, second, and third staged fuel injection circuits respectively, the first, second, and third fuel nozzle valves being operable to open at different first, second, and third crack open pressures respectively, the housing including a single fuel supply connector connected in fuel supply relationship with the first and second fuel nozzle valves and a single fuel signal connector connected in pressure supply relationship with the first and second fuel nozzle valves, the fuel injector conduit comprising a single feed strip having a single bonded together pair of lengthwise extending plates, each of the plates having widthwise spaced apart and lengthwise extending parallel grooves, and the plates being bonded together such that opposing grooves in each of the plates are aligned forming internal fuel flow passages of the first, second, and third staged fuel injection circuits through the length of the strip from an inlet end to an outlet end. 14. A fuel injector as claimed in claim 13 further comprising: the first staged fuel injection circuit being a pilot fuel circuit in an annular main nozzle, the second staged fuel injection circuit being a main nozzle first fuel circuit in the main nozzle, and the third staged fuel injection circuit being a main nozzle second fuel circuit in the main nozzle. 15. A fuel injector as claimed in claim 14 further comprising: the first fuel injection points of the first staged fuel injection circuits are tip orifices in fuel injector tips of pilot nozzles of the fuel injectors, and the second and third fuel injection points are spray orifices in main nozzle first and second fuel circuits respectively in the main nozzles of the fuel injectors. 16. A fuel injector as claimed in claim 15 further comprising further comprising the main nozzle fluidly connected to the outlet end of the feed strip and integrally formed with the feed strip from the bonded together pair of lengthwise extending plates. 17. A fuel injector as claimed in claim 16 further comprising: clockwise and counterclockwise extending annular legs extending circumferentially from at least one of the internal fuel flow passages in each of the main nozzle first and second fuel circuits in the annular main nozzle, the clockwise and counterclockwise extending annular legs of the main nozzle first and second fuel circuits having parallel first and second waves respectively, and the spray orifices are located in alternating ones of the first and second waves so as to be substantially aligned along a circle. | BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to gas turbine engine combustor fuel injectors and, more particularly, such fuel injectors for use in staged fuel supply systems. In order to lower emissions, gas turbine engines are using lean burning combustors which require turning on and off independent fuel circuits over a range of operating conditions including engine power level and environmental conditions. This is often referred to as fuel staging and is required to keep a local fuel/air ratio of the engine within a narrow range defined at its upper limit by NOx emissions and at its lower limit by a flame-out boundary. Current engines use multiple individually controlled centralized staging valves with multiple fuel supply manifolds which deliver fuel to the fuel nozzles. There is one fuel supply manifold for each stage, thus, each fuel nozzle has multiple fuel supply connections, one for each stage. In order to prevent coking, fuel must be either drained from or continuously circulated in the unstaged manifold. These multi-manifold fuel systems are cumbersome and require many looped or bent fuel supply tubes of multiple shapes and sizes to feed the differential staged fuel nozzles. It is desirable to have a fuel system with a single fuel manifold and a fuel injector containing the differential staged fuel nozzles. Fuel systems with multiple centralized staging valves are expensive and engine designers are always striving to build more reliable fuel systems with better operability response. Centralized staging fuel systems exhibit droop in speed during acceleration because unstaged fuel manifolds in such systems must be pressurized and empty volumes filled before fuel flow is attained in the circuit. It is highly desirable to reduce speed droop. Fuel injectors, such as in gas turbine engines, direct pressurized fuel from a manifold to one or more combustion chambers. Fuel injectors also prepare the fuel for mixing with air prior to combustion. Each injector typically has an inlet fitting connected to the manifold, a tubular extension or stem connected at one end to the fitting, and one or more spray nozzles connected to the other end of the stem for directing the fuel into the combustion chamber. A fuel conduit or passage (e.g., a tube, pipe, or cylindrical passage) extends through the stem to supply the fuel from the inlet fitting to the nozzle. Appropriate valves and/or flow dividers can be provided to direct and control the flow of fuel through the nozzle. The fuel injectors are often placed in an evenly-spaced annular arrangement to dispense (spray) fuel in a uniform manner into the combustor chamber. BRIEF DESCRIPTION OF THE INVENTION A multi-staged gas turbine engine fuel supply system fuel injector includes at least first and second staged fuel injection circuits. Each of the first and second staged fuel injection circuits has first and second fuel injection points and at least first and second fuel nozzle valves controllably connected to the first and second staged fuel injection circuits, respectively. The first and second fuel nozzle valves are operable to open at different first and second crack open pressures, respectively. The first and second fuel nozzle valves are located in a valve housing of the injector which includes a single fuel supply connector connected in fuel supply relationship with the first and second fuel nozzle valves and a single fuel signal connector connected in pressure supply relationship with the first and second fuel nozzle valves. In one embodiment of the fuel injectors, the first fuel injection points of the first staged fuel injection circuits are tip orifices in a fuel injector tips of pilot nozzles of the fuel injectors. The second fuel injection points of the second staged fuel injection circuits are spray orifices in main nozzles of the fuel injectors. The system may further include third staged fuel injection circuits having third fuel injection points in the fuel injectors. The third fuel injection points may also be in the main nozzles of the fuel injectors. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematical view illustration of a multi-staged gas turbine engine fuel supply system with only a single fuel supply manifold and only a single fuel signal manifold. FIG. 2 is a schematical view illustration of a three stage gas turbine engine fuel supply system with only a single fuel supply manifold and only a single fuel signal manifold. FIG. 3 is a schematical view illustration of a gas turbine engine fuel supply system with dual two stage fuel injectors with only a single fuel supply manifold. FIG. 4 is a schematical view illustration of a gas turbine engine fuel supply system with dual three stage fuel injectors with only a single fuel supply manifold. FIG. 5 is a cross-sectional view illustration of a gas turbine engine combustor with an exemplary embodiment of a triple staged fuel injector. FIG. 6 is an enlarged cross-sectional view illustration of the fuel injector with the fuel nozzle assembly illustrated in FIG. 5. FIG. 7 is an enlarged cross-sectional view illustration of the fuel nozzle assembly illustrated in FIG. 6. FIG. 8 is a perspective view illustration of the fuel injector illustrated in FIG. 6. FIG. 9 is a cross-sectional view illustration of the fuel strip taken though 9-9 illustrated in FIG. 6. FIG. 10 is a top view illustration of a plate used to form the fuel strip illustrated in FIG. 5. FIG. 11 is a schematic illustration of fuel circuits of the fuel injector illustrated in FIG. 5. FIG. 12 is a perspective view illustration of the fuel strip with the fuel circuits illustrated in FIG. 11. FIGS. 13-16 are schematical view illustrations of two valves illustrating operation of a two valve three stage gas turbine engine fuel supply system for use with only a single fuel supply manifold and only a single fuel signal manifold. DETAILED DESCRIPTION OF THE INVENTION Schematically illustrated in FIG. 1 is an exemplary embodiment of a multi-staged gas turbine engine fuel supply system 8 that provides fuel to first and second staged fuel injection circuits 411 and 412 of each of a plurality of fuel injectors 10. Each of the first and second staged fuel injection circuits 411 and 412 has first and second fuel injection points 413 and 414. First and second fuel nozzle valves 415 and 416 are controllably connected to the first and second staged fuel injection circuits 411 and 412, respectively. A fuel supply circuit 431 includes a single fuel supply manifold 409 connected in fuel supplying relationship to all of the fuel nozzle valves 415 and 416. The first and second fuel nozzle valves 415 and 416 are operable to open at different first and second crack open pressures 419 and 420, respectively, as indicated by the different arrow lengths representing the different crack open pressures. All of the first and second fuel nozzle valves 415 and 416 are controllably connected to a single fuel signal manifold 16 in a signal circuit 433. A more particular exemplary embodiment of the fuel injectors 10 illustrated in FIG. 1 includes the first fuel injection points 413 of the first staged fuel injection circuits 411 being tip orifices 55 in a fuel injector tips 57 of pilot nozzles 58 of the fuel injectors 10 as illustrated in FIGS. 5 and 7. The second fuel injection points 414 of the second staged fuel injection circuits 412 are spray orifices 106 in main nozzles 59 of the fuel injectors 10 illustrated in FIGS. 5 and 7. The system 8 may further include third staged fuel injection circuits 460 having third fuel injection points 462 in the fuel injectors 10 as illustrated in FIG. 2. Third fuel nozzle valves 480 having third crack open pressures 482 are in the third staged fuel injection circuits 460. The system may have more than three staged fuel injection circuits 460 and more than three staged fuel injection points 462 in the fuel injectors 10. The exemplary embodiments of the system 8 illustrated in FIGS. 1 and 2 further includes a differential pressure measuring means 418 for sensing a differential pressure DCPFN between a signal pressure 417 of the signal circuit 433 and a fuel supply pressure 427 of the fuel supply circuit 431. A fuel controller 421 in feedback signal relationship to the differential pressure measuring means 418 controls a pressure regulator 422 controllably connected to the fuel controller 421. The fuel controller 421 by controlling the pressure regulator 422 controls and regulates pressure through the signal circuit 433 and, thus, controls the crack open pressures sent to the fuel nozzle valves from the single fuel signal manifold 16 in the signal circuit 433. The first fuel nozzle valves 415 open and remain open when the pressure in the signal circuit 433 equals or exceeds the first crack open pressure 419. The second fuel nozzle valves 416 open and remain open when the pressure in the signal circuit 433 equals or exceeds the second crack open pressures 420. This eliminates the need for multiple fuel and signal lines to each injector for each stage. A fuel pump 441 is connected in fuel supplying relationship to a fuel metering valve 437 which is connected in fuel supplying relationship to the fuel supply manifold 409. The fuel metering valve 437 is controllably connected to the fuel controller 421. A first pressure input line 435 leads from between the pressure regulator 422 and the signal circuit 433 to the differential pressure measuring means 418. A second pressure input line 436 leads from a point in the fuel supply circuit 431 between the fuel metering valve 437 and the fuel supply manifold 409 to the differential pressure measuring means 418. The differential pressure measuring means 418 is typically a pressure transducer. The pressure transducer may be mechanical or electrical. The fuel pump 441 has a pump outlet 443 connected in fuel pressure supplying relationship to the pressure regulator 422 and also connected in fuel supplying relationship to the fuel metering valve 437. The pressure regulator 422 is also connected in fuel pressure sink relationship by a pressure regulator return line 450 to a booster pump inlet 452 to the booster pump 451 for use during transient conditions or operations. The pressure regulator 422 is a three way servo and is operable to open up the pressure regulator return line 452 when the pressure regulator 422 is set to a closed or off position. Note that a closed or off position does not fully shut off flow through to the fuel signal manifold 16. A pump bypass line 439 leads from the pump outlet 443 to a pump bypass line inlet 440 to the fuel pump 441 and has a bypass valve 445 therein. A signal fuel return line 447 leads from the fuel signal manifold 16 to a signal fuel return inlet 442 to the fuel pump 441. A return line orifice 449 is disposed in the signal fuel return line 447. The return line orifice 449 allows fuel to keep flowing in the signal manifold 409 and avoid coking in the nozzles and lowers pressure gain across the pressure regulator 422 during engine operation. The fuel pump 441 includes a booster pump 451 upstream of and in serial flow relationship to a main pump 453. The pump bypass line inlet 440 is disposed between the booster and main pumps 451 and 453. The signal fuel return line 447 leads from the fuel signal manifold 16 to the signal fuel return inlet 442 to the fuel pump 441 at the booster pump inlet 452 to the booster pump 451. Schematically illustrated in FIGS. 3 and 4 are exemplary embodiments of a multi-staged gas turbine engine controlled pressure fuel supply system 8 that has two or more pluralities of staged fuel injectors 10. The system 8 is illustrated for providing fuel to first and second staged fuel injection circuits 411 and 412 of each of first and second pluralities 406 and 408, respectively, of fuel injectors 10. Each of the first and second pluralities, or more if so provided, may be turned on or off with the other or others turned on. This may be used for circumferential staging. The system 8 illustrated in FIG. 3 is for a double two stage system and the system 8 illustrated in FIG. 4 is for a double three stage system. The fuel supply circuit 431 for both the double two and three stage systems includes a single fuel supply manifold 409 connected in fuel supplying relationship to all of the fuel nozzle valves 415 and 416 for the first and second fuel injection points 413 and 414 of both the first and second pluralities 406 and 408 of the fuel injectors 10 as illustrated in FIGS. 3 and 4. Fuel injectors 10 of the first plurality 406 are interdigitated with fuel injectors 10 of the second plurality 408 such that circumferentially adjacent fuel injectors 10 are from different ones of the first and second pluralities 406 and 408 of the fuel injectors 10. The first and second fuel nozzle valves 415 and 416 are operable to open at different first and second crack open pressures 419 and 420, respectively, as indicated by the different arrow lengths representing the different crack open pressures in the double two stage system illustrated in FIG. 3. Crack open pressures of the first and second fuel nozzle valves 415 and 416 may be the same or different for the first and second pluralities 406 and 408 of the fuel injectors 10. Alternatively, scheduling the opening and closing of the first and second fuel nozzle valves 415 and 416 may be the same or different for the first and second pluralities 406 and 408. The first and second fuel nozzle valves 415 and 416 for the first plurality 406 of fuel injectors 10 are controllingly connected in fuel supply relationship to the first and second fuel injection points 413 and 414, respectively, in the first plurality 406 of fuel injectors 10. The first and second fuel nozzle valves 415 and 416 of the first plurality 406 of fuel injectors 10 are controllably connected to a first fuel signal manifold 456 in a first signal circuit 464 for the first plurality 406 of fuel injectors 10. The first and second fuel nozzle valves 415 and 416 of the second plurality 408 of fuel injectors 10 are controllingly connected in fuel supply relationship to the first and second fuel injection points 413 and 414 respectively in the second plurality 408 of fuel injectors 10. The first and second fuel nozzle valves 415 and 416 for the second plurality 408 of fuel injectors 10 are controllably connected to a second fuel signal manifold 458 in a second signal circuit 478 of the second plurality 408 of fuel injectors 10. The fuel pump 441 is connected in fuel supplying relationship to a fuel metering valve 437 which is connected in fuel supplying relationship to the fuel supply manifold 409. The fuel metering valve 437 of this embodiment located within and controlled by the fuel controller 421. The fuel controller 421 also contains and controls the bypass valve 445 in the pump bypass line 439 leading from the pump outlet 443 to the pump bypass line inlet 440 to the fuel pump 441. First and second signal fuel return lines 347 and 348 leads from the first and second fuel signal manifold 456 and 458, respectively, to the signal fuel return inlet 442 to the fuel pump 441. First and second return line orifices 349 and 350 are disposed in the first and second signal fuel return lines 347 and 348, respectively. The system 8 illustrated in FIGS. 3 and 4 further include a first differential pressure measuring means 468 for sensing a first differential pressure DCPFNl between a first signal pressure 472 of the first signal circuit 464 and a fuel supply pressure 427 of the fuel supply circuit 431. A second differential pressure measuring means 470 is used for sensing a second differential pressure DCPFN2 between a second signal pressure 474 of a second signal circuit 478 and a fuel supply pressure 427 of the fuel supply circuit 431. A fuel nozzle controller 423 is in feedback signal relationship to the first and second differential pressure measuring means 468 and 470 and controls first and second pressure regulators 492 and 494, respectively, which are controllably integrated into the fuel nozzle controller 423. The fuel nozzle controller 423 by controlling the first and second pressure regulators 492 and 494 controls and regulates pressure through the first and second signal circuits 464 and 478 and, thus, controls the pressures sent to the fuel nozzle valves to crack them open and close them. The first fuel nozzle valves 415 open and remain open when the pressure in the signal circuit 433 equals or exceeds the first crack open pressure 419. The second fuel nozzle valves 416 open and remain open when the pressure in the signal circuit 433 equals or exceeds the second crack open pressures 420. The system 8 illustrated in FIG. 4, includes third staged fuel injection circuits 460 having third fuel injection points 462 in the fuel injectors 10. Third fuel nozzle valves 480 having third crack open pressures 482 are in the third staged fuel injection circuits 460. The system may have more than three staged fuel injection circuits 460 and more than three staged fuel injection points 462 in the fuel injectors 10. Illustrated in FIG. 5 is an exemplary embodiment of a combustor 15 including a combustion zone 18 defined between and by annular, radially outer and radially inner liners 20 and 22, respectively. The outer and inner liners 20 and 22 are located radially inwardly of an annular combustor casing 26 which extends circumferentially around outer and inner liners 20 and 22. The combustor 15 also includes an annular dome 34 mounted upstream from outer and inner liners 20 and 22. The dome 34 defines an upstream end 36 of the combustion zone 18 and a plurality of mixer assemblies 40 (only one is illustrated) are spaced circumferentially around the dome 34. Each mixer assembly 40 helps to support pilot and main nozzles 58 and 59, respectively, of one of the fuel injectors 10. The mixer assemblies 40 together with the pilot and main nozzles deliver a mixture of fuel and air to the combustion zone 18. Each mixer assembly 40 has a nozzle axis 52 about which the pilot and main nozzles 58 and 59 are circumscribed. The exemplary fuel injector 10 illustrated in FIG. 5 has three fuel valve receptacles 19 designed to accommodate the first, second, and third fuel nozzle valves 415, 416, and 480 within a valve housing 43 of the fuel injector 10. The first, second, and third staged fuel injection circuits 411, 412, and 460 are illustrated in FIGS. 5, 6, and 7 more specifically as a pilot fuel circuit 288 for the pilot nozzle 58, and main nozzle first and second fuel circuits 280 and 282 for the main nozzles 59 of the fuel injectors 10, respectively. The first, second, and third fuel nozzle valves 415, 416, and 480 (not illustrated in FIGS. 5-7) controllably supply fuel from the single fuel supply manifold 409 to the pilot fuel circuit 288, the main nozzle first fuel circuit 280 and the main nozzle second fuel circuit 282, respectively. The first fuel injection points 413 of the first staged fuel injection circuits 411 are tip orifices 55 in a fuel injector tips 57 of pilot nozzles 58 of the fuel injectors 10. The second and third fuel injection points 414 and 462 are spray orifices 106 in main nozzle first and second fuel circuits 280 and 282 in the main nozzles 59 of the fuel injectors 10. Illustrated schematically in FIGS. 13-16 is the operation of a two valve three stage gas turbine engine fuel supply system 8. The first and second fuel nozzle valves 415 and 416 are used to controllably supply fuel to the tip orifices 55 in the fuel injector tips 57 of pilot nozzles 58 and the spray orifices 106 in the main nozzles 59 of the fuel injectors 10, respectively. The second fuel nozzle valve 416 includes a main fuel inlet port 502 connectable in fuel supply relationship to a main fuel outlet port 506 and a supplemental pilot inlet port 500 connectable in fuel supply relationship to a supplemental pilot outlet port 504. A second spool 508 slideably disposed within the second fuel nozzle valve 416 includes upper and lower peripheral passages 509 and 511 around the second spool 508. The single fuel supply manifold 409 is connected in fuel supply relationship to the main fuel inlet port 502 and the supplemental pilot inlet port 500. The main fuel inlet port 502 is connectable in fuel supply relationship to the main fuel outlet port 506 through the lower peripheral passage 511 around the second spool 508. The supplemental pilot inlet port 500 is connectable in fuel supply relationship to the supplemental pilot outlet port 504 through the upper peripheral passage 509 around the second spool 508. The supplemental pilot inlet port 500 provides a pilot cutback on the second valve 416 to reduce fuel flow to the first valve and subsequently to the pilot nozzles 58. The second spool 508 is biased by a second spring 507 and moved by the differential pressure DCPFN between the signal pressure 417 of the signal circuit 433 and a fuel supply pressure 427 of the fuel supply circuit 431. A first spool 514 having a third peripheral passage 513 is slideably disposed within the first fuel nozzle valve 415. The first fuel nozzle valve 415 includes a pilot fuel inlet port 510 connectable in fuel supply relationship through the third peripheral passage 513 to a pilot fuel outlet port 512. The single fuel supply manifold 409 and the supplemental pilot outlet port 504 of the second valve 416 are connected in fuel supply relationship to the pilot fuel inlet port 510. The first spool 514 is biased by a first spring 517 and moved by the differential pressure DCPFN between the signal pressure 417 of the signal circuit 433 and a fuel supply pressure 427 of the fuel supply circuit 431. The first and second springs 517 and 507 have different resistances and, hence, provide different crack open pressures for the first and second fuel nozzle valves 415 and 416. FIG. 13 illustrates both the first and second fuel nozzle valves 415 and 416 in the shutoff position for which the differential pressure DCPFN between the signal pressure 417 of the signal circuit 433 and the fuel supply pressure 427 of the fuel supply circuit 431 is 0. A cutback orifice 524 in the signal circuit 433 between the first fuel nozzle valve 415 and the fuel signal manifold 16 prevents banging or unwanted high pressure oscillations in the signal circuit 433 and the fuel signal manifold 16. The second spool 508 in the second fuel nozzle valve 416 blocks fuel flow through the main fuel inlet port 502 and on to the main nozzle 59. The first spool 514 in the first fuel nozzle valve 415 blocks fuel flow through the pilot fuel inlet port 510 and on to the pilot nozzle 58. FIG. 14 illustrates the first and second fuel nozzle valves 415 and 416 set for no main nozzle fuel flow to the main nozzle 59 and a relatively high or full pilot fuel flow to the pilot nozzle 58. The second spool 508 is positioned in the second fuel nozzle valve 416 to block fuel flow through the main fuel inlet port 502 and on to the main nozzle 59. This position of the second spool 508 does allow fuel flow through the supplemental pilot inlet port 500, through the peripheral passage 509, around the second spool 508, to the supplemental pilot outlet port 504, and to the pilot nozzle 58. The first spool 514 in the first fuel nozzle valve 415 is positioned to allow fuel flow directly from the single fuel signal manifold 16 through the cutback orifice 524 and from the supplemental pilot outlet port 504 through the pilot fuel inlet port 510 and on to the pilot nozzle 58. This mode or stage of operation provides full fuel flow through the pilot nozzle 58 and no fuel flow through the main nozzle 59. FIG. 15 illustrates the first and second fuel nozzle valves 415 and 416 set for full main nozzle fuel flow to the main nozzle 59 and a relatively high pilot fuel flow to the pilot nozzle 58. The second spool 508 is positioned in the second fuel nozzle valve 416 to allow fuel flow through the main fuel inlet port 502 and on to the main nozzle 59 and through the supplemental pilot inlet port 500, through the peripheral passage 509, around the second spool 508, to the supplemental pilot outlet port 504, and to the pilot nozzle 58. The first spool 514 in the first fuel nozzle valve 415 is positioned to allow fuel flow directly from the single fuel signal manifold 16 through the cutback orifice 524 and from the supplemental pilot outlet port 504 through the pilot fuel inlet port 510 and on to the pilot nozzle 58. This mode or stage of operation provides full fuel flow through the pilot nozzle 58 and full fuel flow through the main nozzle 59. FIG. 16 illustrates the first and second fuel nozzle valves 415 and 416 set for full main nozzle fuel flow to the main nozzle 59 and a relatively low or partial pilot fuel flow to the pilot nozzle 58. This mode also referred to as pilot cutback. The second spool 508 is positioned in the second fuel nozzle valve 416 to allow fuel flow through the main fuel inlet port 502 and on to the main nozzle 59. The second spool 508 is also positioned in the second fuel nozzle valve 416 to block fuel flow through the supplemental pilot inlet port 500 and on to the supplemental pilot outlet port 504 and eventually to the pilot nozzle 58. The first spool 514 in the first fuel nozzle valve 415 is positioned to allow fuel flow directly from the single fuel signal manifold 16 through the cutback orifice 524 and through the pilot fuel inlet port 510 and on to the pilot nozzle 58. Thus, the pilot nozzle 58 does not get the fullest possible fuel flow the system 8 is capable of. The exemplary embodiment of the fuel injector 10, illustrated in FIGS. 5 and 6, has a fuel nozzle assembly 12 (more than one radially spaced apart nozzle assemblies may be used) that includes the pilot and main nozzles 58 and 59, respectively, for directing fuel into the combustion zone of a combustion chamber of a gas turbine engine. The fuel injector 10 includes a nozzle mount or flange 30 adapted to be fixed and sealed to the combustor casing 26. A hollow stem 32 is integral with or fixed to the flange 30 (such as by brazing or welding) and supports the fuel nozzle assembly 12 and the mixer assembly 40. Referring to FIGS. 6 and 8, the hollow stem 32 has an inlet assembly 41 disposed above or within an open upper end of a chamber 39 and is integral with or fixed to flange 30 such as by brazing. Inlet assembly 41 is part of the valve housing 43 with the hollow stem 32 depending from the housing. The housing 43 includes a single fuel supply connector 484 for connecting the single fuel supply manifold 409 to the first, second, and third fuel nozzle valves 415, 416, and 480. The housing 43 further includes a single fuel signal connector 486 for connecting the single fuel signal manifold 16 to the first, second, and third fuel nozzle valves 415, 416, and 480 which are illustrated schematically in FIGS. 2 and 11. The inlet assembly 41 is operable to receive fuel for combustion and signal pressure for cracking open the nozzle valves from the fuel supply manifold 409 and the fuel signal manifold 16, respectively. The first, second, and third fuel nozzle valves 415, 416, and 480 control fuel flow through the main nozzle first and second fuel circuits 280 and 282 for feeding the main nozzle fuel circuits 102 lead to spray orifices 106. The second fuel injection points 414 of the second staged fuel injection circuits 412 are tip orifices 55 in a fuel injector tips 57 of pilot nozzles 58 of the fuel injectors 10 as illustrated in FIGS. 6 and 7. The nozzle assembly 12 includes the pilot and main nozzles 58 and 59, respectively. Generally, the pilot and main nozzles 58 and 59 are used during normal and extreme power situations, while only the pilot nozzle is used during start-up and part power operation. A flexible fuel injector conduit 60 having at least one elongated feed strip 62 is used to provide fuel from the inlet assembly 41 to the nozzle assembly 12. The feed strip 62 is a flexible feed strip formed from a material which can be exposed to combustor temperatures in the combustion chamber without being adversely affected. Referring to FIGS. 9 and 10, the feed strip 62 has a bonded together pair of lengthwise extending first and second plates 76 and 78. Each of the first and second plates 76 and 78 has a single row 80 of widthwise spaced apart and lengthwise extending parallel grooves 84. The plates are bonded together such that opposing grooves 84 in each of the plates are aligned forming internal fuel flow passages 90 through the feed strip 62 from an inlet end 66 to an outlet end 69 of the feed strip 62. A pilot nozzle extension 54 extends aftwardly from the main nozzle 59 and is fluidly connected to a fuel injector tip 57 of the pilot nozzle 58 by the pilot feed tube 56 as further illustrated in FIGS. 6 and 7. The fuel injector tip 57 has a tip orifice 55 that is a fuel injection point of the pilot fuel circuit 288. The pilot fuel circuit 288, the main nozzle first fuel circuit 280, and the main nozzle second fuel circuit 282 are formed by the internal fuel flow passages 90 through the feed strip 62. The feed strip 62 feeds the main nozzle 59 and the pilot nozzle 58 as illustrated in FIGS. 6 and 7. Referring to FIG. 6, the feed strip 62 has a substantially straight radially extending middle portion 64 between the inlet end 66 and the outlet end 69. A straight header 104 of the fuel injector conduit 60 extends transversely (in an axially aftwardly direction) away from the outlet end 69 of the middle portion 64 and leads to an annular main nozzle 59 which is secured, thus, preventing deflection. The inlet end 66 is fixed within the valve housing 43. The header 104 is generally parallel to the nozzle axis 52 and leads to the main nozzle 59. The feed strip 62 has an elongated essentially flat shape with substantially parallel first and second side surfaces 70 and 71 and a rectangular cross-sectional shape 74 as illustrated in FIG. 9. Referring to FIGS. 6 and 12, the inlets 63 at the inlet end 66 of the feed strip 62 are in fluid flow communication with or fluidly connected to first and second fuel inlet ports 46 and 47, respectively, in the inlet assembly 41 to direct fuel into the main nozzle fuel circuit 102 and the pilot fuel circuit 288. The inlet ports feed the multiple internal fuel flow passages 90 in the feed strip 62 to the pilot nozzle 58 and main nozzle 59 in the nozzle assembly 12 as well as provide cooling circuits for thermal control in the nozzle assembly. The header 104 of the nozzle assembly 12 receives fuel from the feed strip 62 and conveys the fuel to the main nozzle 59 and, where incorporated, to the pilot nozzle 58 through the main nozzle fuel circuits 102 as illustrated in FIGS. 11 and 12. The feed strip 62, the main nozzle 59, and the header 104 therebetween are integrally constructed from the lengthwise extending first and second plates 76 and 78. The main nozzle 59 and the header 104 may be considered to be elements of the feed strip 62. The fuel flow passages 90 of the main nozzle fuel circuits 102 run through the feed strip 62, the header 104, and the main nozzle 59. The fuel passages 90 of the main nozzle fuel circuits 102 lead to spray orifices 106 and through the pilot nozzle extension 54 which is operable to be fluidly connected to the pilot feed tube 56 to feed the pilot nozzle 58 as illustrated in FIGS. 5, 6, and 12. The parallel grooves 84 of the fuel flow passages 90 of the main nozzle fuel circuits 102 are etched into adjacent surfaces 210 of the first and second plates 76 and 78 as illustrated in FIGS. 9 and 10. Referring to FIGS. 9-12, the main nozzle first and second fuel circuits 280 and 282 each include clockwise and counterclockwise extending annular legs 284 and 286, respectively, in the main nozzle 59. The spray orifices 106 extend from the annular legs 284 and 286 through one or both of the first and second plates 76 and 78. The spray orifices 106 radially extend outwardly through the first plate 76 of the main nozzle 59 which is the radially outer one of the first and second plates 76 and 78. The clockwise and counterclockwise extending annular legs 284 and 286 have parallel first and second waves 290 and 292, respectively. The spray orifices 106 are located in alternating ones of the first and second waves 290 and 292 so as to be substantially circularly aligned along a circle 300. The first and second fuel nozzle valves 415 and 416 control fuel to the clockwise and counterclockwise extending annular legs 284 and 286 in the main nozzle first and second fuel circuits 280 and 282 in the main nozzle 59. Thus, the spray orifices 106 in one of the first and second waves 290 and 292 may be shutoff while the spray orifices 106 in the other one of the first and second waves 290 and 292 can be left spraying fuel so that only every other one or alternating ones of the spray orifices 106 around the circle 300 are supplying fuel for combustion. The main nozzle fuel circuits 102 also include a looped pilot fuel circuit 288 which feeds the pilot nozzle extension 54. The looped pilot fuel circuit 288 includes clockwise and counterclockwise extending annular pilot legs 294 and 296, respectively, in the main nozzle 59. See U.S. Pat. No. 6,321,541 for information on nozzle assemblies and fuel circuits between bonded plates. Referring to FIGS. 11 and 12, the internal fuel flow passages 90 down the length of the feed strips 62 are used to feed fuel to the main nozzle fuel circuits 102. Fuel going into each of the internal fuel flow passages 90 in the feed strips 62 and the header 104 into the pilot and main nozzles 58 and 59 is controlled by the first, second, and third fuel nozzle valves 415, 416, and 480. The header 104 of the nozzle assembly 12 receives fuel from the feed strips 62 and conveys the fuel to the main nozzle 59. The main nozzle 59 is annular and has a cylindrical shape or configuration. Referring to FIGS. 9 and 10, the flow passages, openings and various components of the spray devices in plates 76 and 78 can be formed in any appropriate manner such as by etching and, more specifically, chemical etching. The chemical etching of such plates should be known to those skilled in the art and is described for example in U.S. Pat. No. 5,435,884. The etching of the plates allows the forming of very fine, well-defined, and complex openings and passages, which allow multiple fuel circuits to be provided in the feed strips 62 and main nozzle 59 while maintaining a small cross-section for these components. The plates 76 and 78 can be bonded together in surface-to-surface contact with a bonding process such as brazing or diffusion bonding. Such bonding processes are well-known to those skilled in the art and provides a very secure connection between the various plates. Diffusion bonding is particularly useful as it causes boundary cross-over (atom interchange) between the adjacent layers. Referring to FIGS. 5 and 7, each mixer assembly 40 includes a pilot mixer 142, a main mixer 144, and a centerbody 143 extending therebetween. The centerbody 143 defines a chamber 150 that is in flow communication with, and downstream from, the pilot mixer 142. The pilot nozzle 58 is supported by the centerbody 143 within the chamber 150. The pilot nozzle 58 is designed for spraying droplets of fuel downstream into the chamber 150. The main mixer 144 includes main axial swirlers 180 located upstream of main radial swirlers 182 located upstream from the spray orifices 106. The pilot mixer 142 includes a pair of concentrically mounted pilot swirlers 160. The pilot swirlers 160 are illustrated as axial swirlers and include an inner pilot swirler 162 and an outer pilot swirler 164. The inner pilot swirler 162 is annular and is circumferentially disposed around the pilot nozzle 58. Each of the inner and outer pilot swirlers 162 and 164 includes a plurality of inner and outer pilot swirling vanes 166 and 168, respectively, positioned upstream from pilot nozzle 58. Referring more particularly to FIG. 7, an annular pilot splitter 170 is radially disposed between the inner and outer pilot swirlers 162 and 164 and extends downstream from the inner and outer pilot swirlers 162 and 164. The pilot splitter 170 is designed to separate pilot mixer airflow 154 traveling through inner pilot swirler 162 from airflow flowing through the outer pilot swirler 164. Splitter 170 has a converging-diverging inner surface 174 which provides a fuel-filming surface during engine low power operations. The splitter 170 also reduces axial velocities of the pilot mixer airflow 154 flowing through the pilot mixer 142 to allow recirculation of hot gases. The inner pilot swirler vanes 166 may be arranged to swirl air flowing therethrough in the same direction as air flowing through the outer pilot swirler vanes 168 or in a first circumferential direction that is opposite a second circumferential direction that the outer pilot swirler vanes 168 swirl air flowing therethrough. Referring more particularly to FIG. 5, the main mixer 144 includes an annular main nozzle housing 190 that defines an annular cavity 192. The main mixer 144 is a radial inflow mixer concentrically aligned with respect to the pilot mixer 142 and extends circumferentially around the pilot mixer 142. The main mixer 144 produces a swirled main mixer airflow 156 along the nozzle housing 190. The annular main nozzle 59 is circumferentially disposed between the pilot mixer 142 and the main mixer 144. More specifically, main nozzle 59 extends circumferentially around the pilot mixer 142 and is radially located outwardly of the centerbody 143 and within the annular cavity 192 of the nozzle housing 190. Referring more particularly to FIG. 7, the nozzle housing 190 includes spray wells 220 through which fuel is injected from the spray orifices 106 of the main nozzle 59 into the main mixer airflow 156. Annular radially inner and outer heat shields 194 and 196 are radially located between the main nozzle 59 and an outer annular nozzle wall 172 of the nozzle housing 190. The inner and outer heat shields 194 and 196 includes radially inner and outer walls 202 and 204, respectively, and there is a 360 degree annular gap 200 therebetween. The inner and outer heat shields 194 and 196 each include a plurality of openings 206 aligned with the spray orifices 106 and the spray wells 220. The inner and outer heat shields 194 and 196 are fixed to the stem 32 in an appropriate manner, such as by welding or brazing. The main nozzle 59 and the spray orifices 106 inject fuel radially outwardly into the cavity 192 though the openings 206 in the inner and outer heat shields 194 and 196. An annular slip joint seal 208 is disposed in each set of the openings 206 in the inner heat shield 194 aligned with each one of the spray orifices 106 to prevent cross-flow through the annular gap 200. The annular slip joint seal 208 may be attached to the inner wall 202 of the inner heat shield 194 by a braze or other method. See U.S. patent application Ser. Nos. 10/161,911, entitled “FUEL INJECTOR LAMINATED FUEL STRIP”, filed Jun. 4, 2002; Ser. No. 10/422,265 entitled “DIFFERENTIAL PRESSURE INDUCED PURGING FUEL INJECTOR WITH ASYMMETRIC CYCLONE”, filed Apr. 24, 2003; and Ser. No. 10/356,009, entitled “COOLED PURGING FUEL INJECTORS”, filed Jan. 31, 2003 for background information on nozzle assemblies and fuel circuits between bonded plates. While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein and, it is therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention. Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH> | <SOH> BRIEF DESCRIPTION OF THE INVENTION <EOH>A multi-staged gas turbine engine fuel supply system fuel injector includes at least first and second staged fuel injection circuits. Each of the first and second staged fuel injection circuits has first and second fuel injection points and at least first and second fuel nozzle valves controllably connected to the first and second staged fuel injection circuits, respectively. The first and second fuel nozzle valves are operable to open at different first and second crack open pressures, respectively. The first and second fuel nozzle valves are located in a valve housing of the injector which includes a single fuel supply connector connected in fuel supply relationship with the first and second fuel nozzle valves and a single fuel signal connector connected in pressure supply relationship with the first and second fuel nozzle valves. In one embodiment of the fuel injectors, the first fuel injection points of the first staged fuel injection circuits are tip orifices in a fuel injector tips of pilot nozzles of the fuel injectors. The second fuel injection points of the second staged fuel injection circuits are spray orifices in main nozzles of the fuel injectors. The system may further include third staged fuel injection circuits having third fuel injection points in the fuel injectors. The third fuel injection points may also be in the main nozzles of the fuel injectors. | 20040331 | 20051018 | 20051006 | 87082.0 | 0 | GARTENBERG, EHUD | CONTROLLED PRESSURE FUEL NOZZLE INJECTOR | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,541 | ACCEPTED | Market expansion through optimized resource placement | A company's ability to expand its market presence by delivering value to emerging and immature markets is influenced by its ability to develop a rich and differentiated value net within these emerging markets. Techniques are disclosed for making resource placement decisions in an objective manner, using results from a value chain analysis. Geographies or locations that are candidates for the resource placement are analyzed in terms of a set of criteria which, in preferred embodiments, are directed toward identifying strengths and weaknesses of each location as part of an overall value chain. | 1. A method of determining resource placement, comprising steps of: determining a set of business objectives for one or more candidate locations; developing one or more objective measurements for each business objective; performing value chain analyses for a product or service to be provided, thereby determining what types of resources will potentially improve the analyzed value chain; developing cost factors pertaining to placing the determined resources in the candidate locations; applying computations that consider the business objectives, according to the developed objective measurements, along with the developed cost factors, to select a particular location from among the candidate locations; and assigning the determined resources to the particular location. 2. The method according to claim 1, wherein the applying step further comprises the step of estimating and accounting for any lag time characteristics discovered while performing the value chain analyses. 3. The method according to claim 1, wherein the assigned resources are information technology personnel. 4. The method according to claim 1, wherein the assigned resources comprise monetary investments in the particular location. 5. A method of analyzing resource placement, comprising steps of: identifying a plurality of candidate locations for placement of resources; identifying a plurality of criteria with which a decision is to be made for placement of the resources; selecting weights that may be used in computations for reflecting business objectives of a company for which the decision is to be made; creating a product profile that specifies values for first selected ones of the identified criteria; creating a geography profile for each of the identified candidate locations, where each geography profile specifies location-specific values for second selected ones of the identified criteria; and using the values specified in the product profile, the values specified in the geography profiles, and the weights to compute one or more location-specific resource placement scores for each of the candidate locations. 6. The method according to claim 5, further comprising the step of selecting one of the candidate locations using the computed location-specific resource placement scores. 7. The method according to claim 6, further comprising the step of placing the resources in the selected one of the candidate locations. 8. The method according to claim 5, further comprising the steps of: selecting a plurality of the candidate locations using the computed location-specific resource placement scores; and placing the resources in the selected plurality of candidate locations. 9. The method according to claim 5, wherein: a single candidate location is identified instead of a plurality thereof; a single geography profile is created for this single candidate location; and the using step uses the values specified in the product profile, the values specified in the single geography profile, and the weights to evaluate how suitable the single candidate location is for the placement of the resources. 10. The method according to claim 5, further comprising the step of defining objective measurements for the identified criteria. 11. The method according to claim 10, further comprising the step of using the defined objective measurements when specifying the location-specific values in the geography profiles. 12. A system for assigning resources, comprising: means for determining a set of business objectives for one or more candidate locations; means for developing one or more objective measurements for each business objective; means for performing value chain analyses for a product or service to be provided, thereby determining what types of resources will potentially improve the analyzed value chain; means for developing cost factors pertaining to placing the determined resources in the candidate locations; means for applying computations that consider the business objectives, according to the developed objective measurements, along with the developed cost factors, to select a particular location from among the candidate locations; and means for assigning the determined resources to the particular location. 13. A computer program product for analyzing resource placement, the computer program product embodied on one or more computer-readable media and comprising computer-readable program code means for carrying out steps of: identifying a plurality of candidate locations for placement of resources; identifying a plurality of criteria with which a decision is to be made for placement of the resources; selecting weights that may be used in computations for reflecting business objectives of a company for which the decision is to be made; creating a product profile that specifies values for first selected ones of the identified criteria; creating a geography profile for each of the identified candidate locations, where each geography profile specifies location-specific values for second selected ones of the identified criteria; and using the values specified in the product profile, the values specified in the geography profiles, and the weights to compute one or more location-specific resource placement scores for each of the candidate locations. 14. A method of providing a resource placement determination service, comprising steps of: identifying a plurality of candidate locations for placement of resources; identifying a plurality of criteria with which a decision is to be made for placement of the resources; creating a product profile that specifies values for first selected ones of the identified criteria; creating a geography profile for each of the identified candidate locations, where each geography profile specifies location-specific values for second selected ones of the identified criteria; using the values specified in the product profile and the values specified in the geography profiles to compute one or more location-specific resource placement scores for each of the candidate locations; and charging a fee for carrying out one or more of the steps of identifying the plurality of candidate locations, identifying the plurality of criteria, creating the product profile, creating each of the geography profiles, and using the values. 15. A method of providing a resource placement validation service, comprising steps of: identifying a location that has been selected for placement of resources; identifying a plurality of criteria pertaining to placement of the resources in an arbitrary location, as if the identified location had not been selected; creating a product profile that specifies values for first selected ones of the identified criteria; creating a geography profile for the selected location, where the geography profile specifies location-specific values for second selected ones of the identified criteria; using the values specified in the product profile and the values specified in the geography profile to compute one or more location-specific resource placement scores for the selected location; and charging a performance fee for carrying out one or more of the steps of identifying the location, identifying the plurality of criteria, creating the product profile, creating the geography profile, and using the values. 16. The method according to claim 15, further comprising the steps of: making a recommendation, based on the one or more computed location-specific resource placement scores, as to the selected location; and charging a recommendation fee for carrying out the step of making the recommendation, where the recommendation fee may be in addition to, or in place of, the performance fee. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to expanding markets for products and services by making resource placement decisions in an objective manner, and deals more particularly with techniques for comparing one or more locations to a set of criteria that are directed toward identifying market strengths and weaknesses of the location(s) as part of an overall value chain. 2. Description of the Related Art Many countries or localities represent an untapped or an emerging market for the sale and adoption of information technology (“IT”). Often, these same countries are simultaneously experiencing a high growth rate in the availability of skills supportive of IT. Connections between a company's business and marketing strategy (and its related decisions) and its resource placement strategy (and its related decisions) may be revealed by examining and understanding the value chain in which the company participates. A value chain is defined as a sequence or network of transactions and mutually-beneficial relationships occurring between companies in the delivery of value to an end customer. Value chains have also been referred to as supply chains and value nets. Economists as far back as Adam Smith have described in great detail how value chains work, especially with regard to how such chains allow for and encourage specialization of business roles, and how they also drive more responsive business systems over time. As an example, consider a simple value chain that corresponds to a hardware supply chain, wherein a wholesale hardware manufacturer supplies a hardware product directly to a retailer who in turn sells it to an end customer. The hardware manufacturer receives value from the retailer because the retailer enables the manufacturer's products to reach the marketplace; this link in the value chain provided by the retailer supports and sustains further orders for the products provided by the manufacturer, thereby causing an increase not only in the manufacturer's revenue but also in the revenue of the retailer. The retailer receives value from the hardware manufacturer in terms of obtaining products that will meet needs of customers in this marketplace. The end customer receives value from the retailer, who provides the customer with an opportunity to buy the needed product, and in turn, the retailer receives value from the customer from the sale of the products. Other benefits may also result, such as increased market presence or brand awareness, and so forth. Symbiotic relationships thus exist between entities in the value chain. More complicated value chains, which may be recursive in some cases, are seen in the IT field. FIG. 1 illustrates representative entities in a sample IT-related value chain. A plurality of components 110 may be required in this particular chain, for example, and these components may be adapted for use with a plurality of operating systems 120. In the more general case, a number of entities (see, for example, reference number 130 in FIG. 1) may be involved in creating one or more IT solutions 140, which may be marketed through one or more distribution channels 150. With these simple examples, it should be clear how companies become part of a value chain and also how they become dependent on both the upstream and downstream vitality and growth of other links in the chain. No company in a mature and free market is likely to own the entire chain of value. In fact, economists use the complexity of a value chain as one indicator of a market's (and a country's) economic maturity. It therefore follows that a company's ability to expand its market presence by delivering value to emerging and immature markets is influenced and limited by its ability to develop a rich and differentiated value net within these emerging markets. Accordingly, it is desirable to provide techniques that leverage a value chain analysis approach for determining optimal resource placement, particularly in emerging IT markets. SUMMARY OF THE INVENTION An object of the present invention is to provide techniques for leveraging a value chain analysis approach to determine optimal resource placement in order to expand markets. Another object of the present invention is to provide techniques for determining optimal resource placement in emerging IT markets. A further object of the present invention is to make resource placement decisions using objective criteria. Another object of the present invention is to provide techniques for determining optimal resource placement decisions using business growth and marketing, rather than purely cost-oriented, objectives. Yet another object of the present invention is to objectively select among a plurality of candidate locations for resource placement. Another object of the present invention is to provide techniques for comparing labor localities using cost as well as marketing/growth criteria and objectives. A further object of the present invention is to provide techniques for presenting resource placement decision factors in a manner that improves acceptance and understanding of the placement decision by the overall work force and the marketplace. Other objects and advantages of the present invention will be set forth in part in the description and in the drawings which follow and, in part, will be obvious from the description or may be learned by practice of the invention. To achieve the foregoing objects, and in accordance with the purpose of the invention as broadly described herein, embodiments of the present invention may be provided as methods, systems, and/or computer program products. In one aspect, preferred embodiments comprise determining a company's business objectives, preferably in terms of candidate locations; developing objective measurements for those business objectives; performing value chain analyses for products/services to be provided by the company; deciding what types of human resources may improve the value chain; estimating and accounting for lag time characteristics, if any, that may be found in the value chain; developing cost factors, and bounds or limits on those factors, as appropriate; performing analyses that use the marketing factors as well as the cost factors; and assigning the human resources accordingly. This aspect is illustrative, but not limiting, of the scope of the present invention. The present invention may also be used advantageously in methods of doing business. For example, a company may provide a service for assessing products and candidate locations, thereby suggesting where the client should place its human resources. As another example, a company may implement a service whereby another company's resource placement decisions can be validated prior to implementation. When provided for a fee, a service of either type may be provided under various revenue models, such as pay-per-use billing, a subscription service, monthly or other periodic billing, and so forth. The present invention will now be described with reference to the following drawings, in which like reference numbers denote the same element throughout. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates entities in a sample value chain for IT products; FIG. 2 depicts various techniques for increasing a product's gross profits; FIGS. 3 and 8 provide flowcharts depicting actions that are preferably carried out when using preferred embodiments of the present invention; FIG. 4 depicts sample assessment criteria for a hypothetical product for which a resource placement decision is to be made; FIG. 5 provides an example showing how objective measurements for a particular criterion may be defined; FIG. 6 depicts sample values of a product profile, and FIG. 9 depicts sample values of two geography profiles, where these profiles are illustrative of those created according to preferred embodiments of invention; FIG. 7 contains a set of sample correlator values of the type that may be used for weighting computations carried out during a resource placement determination; and FIG. 10 (comprising FIGS. 10A-10E) provides sample scores that are illustrative of the types of scores that may be computed, using preferred embodiments of the present invention, to objectively analyze candidate locations for resource placement. DESCRIPTION OF PREFERRED EMBODIMENTS Building a market presence and base of skills in an emerging market is important, especially for products and services which move through a complex value chain, such as IT products. Having such a presence in an emerging market provides many advantages. It provides pragmatic information and insight into the business problems occurring within a target market. It also provides language skills, and serves to initiate useful and financially profitable two-way relationships with local businesses and business partners. Techniques for pursuing marketing objectives, supported in part by labor placement and sourcing decisions, would allow a business to pursue its overall business strategy in a more balanced and integrated manner. Management decisions regarding the placement and sourcing of labor resources (referred to hereinafter as resource placement or labor placement decisions) have traditionally and largely hinged on lowering employee-related expenses. Recent trends in placing work in other countries, sometimes called “off-shoring,” reveal a similar focus on the expense side of the balance sheet. Yet such a cost-centered approach in handling employee-related decisions misses a broader, more value-laden, and more integrated approach in executing a company's overall business strategy—one in which marketing and growth objectives of the company are primary, with cost and expense objectives being of lesser importance in labor placement decisions. Value chains were discussed above, and a sample IT value chain was depicted in FIG. 1. In the same manner and for the same general reasons that businesses are considered integral links in a value chain, employees may also be considered as part of a large value chain. For example, each employee enables (to a greater or lesser extent, depending on their location in a value chain) other employees in the value chain. Their skills and specialties allow other employees in the chain to in turn specialize and to provide incremental and unique value to the chain. Some employees, based on the skills they provide to the chain of value, enable other links and even other value chains to exist. For example, a software developer can support other links in the value chain by not only directly contributing a software product or components thereof, but also by serving the sales force during technical discussions with a customer. Moreover, that same developer can also provide other developers in other companies (e.g., independent software vendors or “ISVs”, systems integrators, etc.) with instruction, consulting, or with programming assets in order to take advantage of the developer's software. In this way, one link in the chain supports others in the chain. In the case where development resources are company employees, benefits in the value chain exist by exploiting or leveraging the employees' influence in such areas as technical instruction (by formal and/or informal means), writing technical articles or white papers, mentoring, providing a local knowledge source, consulting with customers, and so forth—all in conjunction with benefits contributed by those in sales, marketing, and/or system integration roles. If software products are delivered via business partners, then the same software developer influences are available, and a company may benefit by achieving even tighter linkages with the business partner. For example, the company may leverage the business partner to not only perform development work for the company but to also provide other functions such as technical sales or pre-sales support, marketing, and/or installation activities that take advantage of the skills gained by the business partner, thereby augmenting capabilities of the company's own employees. The term “spiral partners” is used herein when referring to this special type of business partner. It can be especially valuable to train spiral partners in a company's products by engaging with them in a vendor relationship to build skills that may contribute, in this manner, to aspects of the company's business beyond the initial delivery of the product. As a result, the skills base of the vendor may thereby expand and support additional needs that exist within the value chain (e.g., supporting needs and activities that are “downstream”, in terms of the value chain, of the product development effort). In contrast, there are other employees and jobs, generally near the end of the value chain, which provide little additional enabling value to the chain (e.g., call center and service representatives). Employees in these jobs still provide irreplaceable value to the chain, but they typically have little ability to enlarge the chain beyond their immediate contribution. Understanding where companies and their employees sit in a value chain is important to making resource placement decisions, and as disclosed herein, those decisions are preferably made by coupling human resource placement decisions to current and future growth and marketing objectives. In so doing, a company can develop a more optimal, balanced, and more growth-oriented resource placement strategy. The desired effect and focus of such employment decisions are preferably based on market share expansion and/or other types of growth opportunities and, in contrast to prior art techniques, are no longer merely determined by cost factors. Decisions about where to locate a company's labor force may be influenced by a number of related factors, including (but not limited to) the availability of a skilled labor force, government regulations and incentives, tax laws, education levels of the labor pool, language fluency, relative cost of living, ease of access, maturity of the distribution system, the cost of capital, labor cost, and/or labor attrition. These factors typically vary by country and also generally vary over time. In addition, market factors may also be considered in the labor placement decision. Examples of these market factors include (but are not limited to) the presence of suppliers, the presence of competitors, and/or the maturity of the market for a company's products. Preferred embodiments of the present invention determine optimal resource placement using results from a value chain analysis, objectively analyzing candidate locations by considering a company's market and revenue objectives in addition to using standard cost-oriented decision criteria. Labor placement decisions thus directly support market expansion objectives rather than mere labor expense objectives. Further, these placement decisions are based on the maturity, complexity, and overall strength of the value chain in the emerging markets, both in terms of employee skill base and the presence of ready business partners. This market approach is in contrast to prior art techniques for base resource placement decisions, which do not consider an overall value chain but instead are focused primarily on reducing labor costs. See FIG. 2, where techniques for increasing a product's gross profits are illustrated graphically. As shown therein at reference number 200, a sample product “X” may have a certain base cost or expense and a certain base revenue, and subtracting the cost from the revenue yields the gross profit for product “X”. Lowering the product's expenses, as illustrated as 210, does not increase revenue. Thus, the gross profit is increased only to the extent that the costs can be decreased. Alternatively, efforts can be directed toward adding selected skills to areas of a company or value net that is producing or delivering product “X”. For example, additional sales staff can be added to increase revenue. This approach, however, necessarily increases cost, as shown at 220. As will be obvious, to increase gross profit when using this approach, the increase in revenue generated by the added skills must exceed the increase to the product's cost. Reference number 230 illustrates the approach used by embodiments of the present invention, where a value chain is improved by leveraging resources in an optimized manner. A goal of this approach is to increase revenue and to reduce costs at the same time, providing a double benefit to gross profits. The behaviors illustrated at 230 are particularly likely to result in appropriately-selected emerging markets because the value chains are less mature and the competitive forces are less well-tuned and arrayed. According to preferred embodiments, a value chain analysis is built using a set of business and marketing objectives. The particular objectives to be used in an assessment are preferably specific to each value chain, although certain criteria may apply generally to a broad spectrum of analysis efforts. In preferred embodiments, criteria-specific weightings may be applied in order to account for nuances of a particular value chain. For example, cost factors of placing resources in a location may be weighted in light of market and growth opportunities that exist for a company's products in a target location or area (referred to herein generally as a location). And, more than one candidate location may be evaluated for a particular resource placement decision, such that an objective selection can be made among the candidates. (It should be noted that while discussions herein are prarily in terms of resource placement for software products, the disclosed techniques may also be used advantageously with other types of products as well as with services and with combinations of products and services.) Accordingly, a primary goal of an assessment conducted using techniques of the present invention is to provide a recommendation on where to locate which types of labor and in what quantities. A complementary goal is to improve a company's business position by focusing on any gaps or shortfalls that may present in the value chain at the candidate locations. Location-specific scores are computed to assist in reaching these goals, as will now be described with reference to FIGS. 3-10. FIG. 3 provides a flowchart that illustrates, at a high level, actions that are preferably carried out when establishing an assessment process according to preferred embodiments. At Block 300, a set of assessment criteria are determined. These criteria will be used when gathering input for the resource placement decision. Preferably, the criteria comprise factors that affect linkages in the value chain and are instrumental in influencing—for a specific product, product family, or brand for which a placement decision is being analyzed—the desirability of each candidate location. (References herein to evaluating a product are intended to include evaluations of products or services comprising a family or brand.) Objective measurements for the criteria are defined (as discussed in more detail with reference to Block 310, below). Preferred embodiments strive to eliminate subjectivity, and these objective measurements are key to accomplishing that goal. In preferred embodiments, each criterion will be rated with a numeric value to reflect how well a candidate location meets that criterion, using the objective measurements. The numeric value is preferably selected from a predetermined range, and is subsequently provided as input to an algorithm (or algorithms) that generates scores for ranking the candidate locations. Preferably, a range of 1 to 5 is used for measuring each of the criteria. In the examples used herein, a value of 5 indicates the best case, and 1 represents the worst case. The relative importance to the product under evaluation, or the relative significance or strength, of appropriate ones of the criteria is preferably determined (Block 305), and a numeric value is preferably assigned accordingly, thereby forming what is referred to herein as a “product profile”. In preferred embodiments, a range of 1 to 5 is used, where 5 indicates a criterion that is extremely important to this product and 1 indicates a criterion that is of very little importance. (The “appropriate ones” of the criteria are discussed in more detail with reference to the sample product profile in FIG. 6.) In practice, a multiple-choice entry technique (such as a graphical user interface representation having selectable radio buttons) is preferably provided for entry of the values in the product profile. In Block 310, objective measurements for each criterion are determined, as discussed above. In preferred embodiments, ensuring that the measurements will be objective is facilitated by developing textual descriptions for each numeric value in the selectable range. These textual descriptions are designed to assist candidate location assessors in performing an objective, rather than subjective, assessment. Preferably, the textual descriptions are defined so that a criterion will be assigned a score of 3 if the candidate location meets requirements for that criterion, a score of 4 if the product exceeds requirements, and a score of 5 if the product significantly exceeds requirements. On the other hand, the descriptions preferably indicate that a candidate location that has minor deviations from the requirements of a criterion (but fails to completely meet requirements) will receive a score of 2 for that criterion, and a candidate location that has significant deviations from the requirements for the criterion will receive a score of 1. Assigning the values, based on these objective measurements, occurs during an assessment of candidate locations, as discussed below with reference to FIG. 8, and the set of values assigned to each candidate location are referred to herein as a “geography profile”. One or more correlators may be defined (Block 315), where each correlator serves as a weight in an algorithm or algorithms, enabling each measurement criterion to have a variable influence on the score or scores that will be computed when evaluating candidate locations. Preferably, correlators are defined in terms of the business objectives that are important to the company seeking to make a resource placement decision. (Accordingly, the sample data in FIG. 7 illustrates use of market share, revenue, and cost reduction as example business objectives for which correlators are defined.) In the examples provided herein, correlators are defined as values between +1.0 and −1.0, and are separately assigned for market share, revenue, and cost reduction. Use of correlators is discussed in more detail below, with reference to FIG. 7. The manner in which the individual correlatQr values are chosen does not form part of the present invention, and an iterative approach may be used if desired. By appropriate selection of the product profile values and correlators, the location-specific resource placement scores determined during the assessment process can be tuned to more precisely reflect the requirements of the evaluated product. Block 320 indicates that a questionnaire is preferably developed for use when gathering data for the candidate locations. A written questionnaire may be used to solicit information that will subsequently be provided as input to an algorithm or algorithms; alternatively, information may be submitted directly into an electronic questionnaire. In preferred embodiments, the electronic questionnaire corresponds to a spreadsheet or other type of automated data entry mechanism (such as a prompting wizard application that will lead a user through entry of information) that can both receive inputs and apply algorithmic manipulations to the entered data to create scores or rankings for the candidate locations. (Or, separate programmatic means may be used for entering the data and for applying the algorithmic manipulations, without deviating from the scope of the present invention.) See the discussion of FIG. 8, below, for more information regarding how the location-specific information is used. A process may be defined (Block 325) for gathering the measurement data that will be used in the assessment. This may further comprise identifying sources of relevant information for each candidate location, such as census data or other government reports describing the available labor pool in that location. One or more algorithms or computational steps are preferably defined (Block 330) to use the measurement data for computing one or more location-specific scores for resource placement. As noted above, preferred embodiments encapsulate the algorithm(s) in a spreadsheet or other automated technique. Optionally, one or more trial assessments may then be conducted (Block 335) to validate the criteria, weights, measurements, and/or algorithms. For example, one or more existing products for which a resource placement decision has already been made may be assessed, and the results thereof may be analyzed to determine whether an appropriate set of factors has been put in place. If necessary, adjustments may be made, and the process of FIG. 3 may be repeated. By way of example, sample criteria 400 for a hypothetical product are shown in FIG. 4. A set of skills 410 which are deemed to be important for this product are enumerated. As shown in the example, the evaluation of local skills needs to address the following criteria: design/development skills; test (i.e., product debugging) skills; maintenance/support skills; skills in programming languages (and in particular, skills in C, C++, and Java™ programming languages); ability to use several operating systems (and in particular, Windows™, Linux™, and AIX® operating systems); and language fluency in English, Chinese, and Japanese. So, for example, if availability of design/development skills is extremely important to this product, then a value of 5 would be assigned to this criterion in the product profile, and if a candidate location significantly exceeds the requirements for design/development skills, then that location would be assigned a value of 5 in its geography profile for purposes of the assessment. (FIG. 8 provides sample values for geography profiles of two hypothetical candidate locations.) Returning briefly to the topic of value chains, when placing resources in an emerging market, it is important to ensure that those resources reflect the right set of skills at the right time in the right order, thereby enabling the value chain to function and mature in an optimal manner. For example, rather than placing only a group of software developers into an emerging market, linkages in the value chain can often be strengthened by placing employees in other job categories within the value chain—such as software testers, maintenance/support personnel, and software integrators—in that location as well. The software developers, as an example, may be able to perform better if they are located relatively near the software testers. Similarly, the software testers may perform better if they are located relatively near the software developers, and so forth. Accordingly, the assessment criteria shown in the example (see reference number 410) include different types of job categories, and by considering each of the included job categories when assessing each candidate location, costs and benefits of placing resources can be assessed in terms of the overall value chain. This is in contrast to making resource placement decisions by considering costs of the various job categories in isolation, as is typically done in the prior art. (As will be obvious, the job categories to be included in a particular assessment may vary, and therefore the categories shown at 410 are by way of illustration only.) Turning again to FIG. 4, reference number 420 identifies a set of criteria that pertains to economic data of the overall marketplace, and reference 430 identifies corresponding criteria that pertain to the candidate locations (where the term “geography” is used in FIG. 4 to refer to a candidate location). In this example, the economic data of importance comprises the worldwide (“WW”) market opportunity for the product; the worldwide compound growth rate (“CGR”); and the worldwide market share for the product, as well as corresponding location-specific values thereof. If the product opportunity is significant on a worldwide basis, or perhaps significantly exceeds the opportunity for other potential products, then a value of 5 would be used in the product profile. And, if the product opportunity in a particular location is very low or insignificant, then a value of 1 would be used in the geography profile for that location. Environmental information pertaining to the locations is represented at reference number 440, and in this example, includes personnel cost (which preferably covers salary, training, benefits, and so forth); general business cost (which preferably includes any required taxes that must be paid in this location, costs of dealing with applicable regulations and laws, and other required overhead expenditures); an estimate of the expected degree of attrition in the labor pool in this location; and the growth rate in applicable skills. As noted in the commentary in FIG. 4, a value of 1 should be assigned in the geography profile if expected attrition is high, thereby effectively disfavoring this location; by contrast, a value of 5 should be assigned if expected attrition is low. Factors such as the number of college graduates per year who have relevant skills may be factored into the location-specific value assigned to the environmental growth rate when constructing a geography profile. Criteria for product sales and delivery are specified at 450. In this example, the criteria pertain to identifying the means by which the company seeking to place its labor resources delivers product to the end customer in the selected location, utilizing the following: direct product integration, support, and sales force; via business partners; and via spiral partners, which were discussed above. Recognizing how the product is delivered can be important in determining where to strengthen the linkages in the value chain. Finally, a set of sample criteria 460 is included that pertains to products that compete with the product for which a resource placement decision is to be made. In this example, the worldwide strength of the competition and the strength within each geography is to be measured, along with the degree to which the local labor pool is already ingrained in competing technology. As will be obvious, additional and/or different criterion may be used, and embodiments using different criteria are considered to be within the scope of the present invention. An example showing how objective measurements for a particular criterion may be defined is provided in FIG. 5. This example 500 corresponds to the criterion shown at reference number 411 of FIG. 4; see reference number 510, where the descriptive text associated with the criterion has been entered. In this example, additional text is provided at 520 to clarify the purpose of this criterion, and a set of one or more points to be considered when evaluating how well a candidate location meets requirements for this criterion is provided at 530. Measurement guidelines 540 are provided, stating the 5 possible values for each criterion along with text explaining how to select among the values. It is to be understood that the information in FIG. 5 is merely illustrative, and other approaches may be used without deviating from the scope of the present invention. As one example, the information shown at 530 might be further defined in terms of the values. That is, rather than setting out a set of general guidelines, as illustrated, a specification might be provided such as “Assign a value of 1 if Java programming skills are not available; assign a value of 2 if Java programming skills are available to a limited degree; . . . ”. Preferably, information of the type shown in FIG. 5 is readily available to assist users during an evaluation. Help information may be generated from information illustrated for the definition 520, information required 530, and/or measurement guidelines 540. Or, a user interface display might (for example) present the items from information required 530, along with radio buttons or checkboxes that can be activated by the user to indicate how well the candidate location meets these objectives. (The user may be allowed to directly enter numeric values that will be used during an assessment, or the numeric values may be programmatically generated based on selections the user makes. For example, if a user is presented with checkboxes for the 7-items shown at reference number 530 of the sample data, but is unable to check any of those boxes as being met for a candidate location, then underlying logic may assign a value of 1 for this criterion, indicating that the location deviates significantly from the required skills.) FIG. 6 shows values for a sample product profile, using the sample criteria from FIG. 4. (Note that profile values are not deemed appropriate for the criteria which are generally categorized as geography marketplace 430 and geography environment 440.) As can be seen from the sample product profile 600, availability of design/development skills 601 and fluency in English 602 are both assigned a value of 5, indicating that these criteria are considered to be extremely important to this hypothetical product. On the other hand, language fluency in Chinese and Japanese is considered unimportant to this product; see reference number 603. Sample correlator values 700 are provided in FIG. 7, and are presented alongside the corresponding criteria from FIG. 4. As noted above, correlators ranging between +1.0 and −1.0 are used as weights in preferred embodiments, and as shown in FIG. 7, correlator values are provided (by way of example) for revenue, market share, and reducing overall cost. Correlator values are used, in combination with values from the product profile and geography profile, to create numeric values that factor into the candidate location scores. In preferred embodiments, at least one correlator must be defined for each criteria. A negative number indicates an inverse correlation (i.e., one that negatively affects the desired output value) and a positive number indicates a positive correlation (i.e., one that positively affects the desired output value). A very strong correlation would have a value approaching 1.0, whereas a very weak correlation might have a value of 0.1, no correlation would have a value of 0, and so forth. Note that a negative correlator number is used in the examples for the criterion pertaining to strength of the company's competition in market share and revenue, as shown in rows 740 and 750 of FIG. 7, such that the assessment computations used in preferred embodiments generate a higher positive score in locations where the competitor does poorly. This positive score will therefore aid in favoring this candidate location over one where the competitor is entrenched. Note also that a relatively high negative correlator has been assigned to attrition, as it pertains to a company's cost reduction goals. See reference number 732. This indicates that attrition has a large negative impact on ability to reduce costs, and a candidate location having a high value in its geography profile for the attrition criterion will therefore receive a lowered score when the (negative) result of multiplying the cost reduction correlator by the attrition value is factored into subsequent computations. Once the information discussed with reference to the flowchart in FIG. 3 (and illustrated by FIGS. 4-7) has been obtained, it is then combined with location-specific information to generate the resource placement scores. This juxtaposition is depicted in the flowchart of FIG. 8. In Block 800, the candidate location or locations are identified. Relevant information for those locations is gathered (Block 805) or otherwise obtained, preferably by consulting sources identified during the processing of Block 325 of FIG. 3. Using that information, values are assigned to the criteria (except, in preferred embodiments, for those criteria that pertain to the product on a worldwide basis) for each candidate location at Block 810, thereby forming location-specific geography profiles. As discussed above, a value of 1 to 5 is assigned, in preferred embodiments, to indicate how well that particular candidate location does regarding each of the appropriate criteria. Preferably, the objective measurement information created at Block 310 of FIG. 3 (an example of which is shown at reference numbers 530 and 540 in FIG. 5) is used during Block 810 when selecting each value, and data entry techniques such as selectable radio buttons numbered 1 through 5 may be provided. At this point, preferred embodiments have the input data that is needed by the algorithm(s), and computations are then performed (Block 815) to create the location-specific scores. These scores are then provided to the user (Block 820), for example by displaying values on a graphical display and/or printing a report that contains this information. FIG. 9 illustrates two sample geography profiles 900, 910, and shows how the values therein relate to the corresponding assessment criteria provided in FIG. 4. Values used to create these profiles 900, 910 are provided at Block 810 of FIG. 8. As shown by the example in FIG. 9, the two hypothetical candidate locations are considered equal in terms of the availability of skills pertaining to the Linux and AIX operating systems (see reference numbers 901 and 911), while pronounced differences are found in other criteria such as the strength of the competition in each location (see reference numbers 903 and 913). A number of different scores may be computed based on the product profile, geography profiles, and correlators. (Alternative embodiments of the present invention may omit use of correlators, without deviating from the inventive concepts disclosed herein.) Scores computed in preferred embodiments will now be described with reference to the example values shown in FIGS. 10A-10E. In FIG. 10A, a per-location score referred to herein as a “skills gap′” score is illustrated. In preferred embodiments, a set of skill gap numbers is computed by subtracting each geography profile value from the corresponding product profile value for each criteria that pertains to local skills (where local skills criteria are shown, by way of example, at reference number 410 in FIG. 4). Column 1000 in FIG. 10A shows the individual skill gap numbers for the candidate location “A” and column 1010 shows the numbers for candidate location “B”. Note that if there is no gap for a particular one of the criteria (i.e., the subtraction operation is not a positive number), its skill gap number is set to 0 in preferred embodiments. For example, geography profile 900 of FIG. 9 indicates that test skills and Chinese language skills (having values of 5, in both cases) found in this candidate location exceed what is required for the product represented by product profile 600 in FIG. 6 (which has corresponding values of 3 and 1, respectively). Thus, there is no “gap” in skills for these criteria; the skill gap numbers are therefore set to 0 in column 1000, as shown at 1001 and 1002. Once the skill gap numbers are computed for each candidate location, they are preferably summed to create the overall skill gap score for that location. This overall skill gap score can then be compared among the candidate locations. For the 13 sample local skills criteria against which the two geography profiles 900, 910 of FIG. 9 were evaluated, the resulting skill gap scores are 10 and 14, respectively, thus indicating that candidate location “B” has a larger skills gap than candidate location “A”. See row 1240 of FIG. 10E, where the overall skills gap scores are presented. FIG. 10B shows 3 sets (i.e., 6 columns) of location-specific values that are computed using the correlator values in combination with the product profile and geography profiles. In preferred embodiments, an algorithm appropriate for each of the criteria pertaining to local skills is utilized in these computations (and the algorithms may vary from one criteria to another). In the example shown in FIG. 10B, the following algorithm is used for each of the local skills criteria: i. The geography profile value is subtracted from the corresponding product profile value. ii. If the result is 0 (i.e., there is no skills gap), then a fixed value of 5 is assigned (thereby strongly favoring the candidate location associated with this geography profile in subsequent computations). iii. Otherwise, computations are performed using each of the correlators in combination with the corresponding product profile value and geography profile value. The details of the particular computation are not material to the present invention, and different computations may be deemed useful in different embodiments of the present invention. Using this algorithm, the values in column 1020 therefore represent computations performed using as input the following: the product profile values (illustrated in FIG. 6); the geography profile values for candidate location “A” (illustrated in column 900 of FIG. 9); and the market share correlator values (illustrated in column 710 of FIG. 7). As stated above, preferred embodiments use only those values, in each case, that pertain to local skills. Similarly, the values in column 1030 represent computations performed using these same inputs, except that the geography profile values for candidate location “B” are used now instead of the values for candidate location “A”. The values in columns 1040 and 1050 use the same inputs as columns 1020 and 1030, except that the revenue correlator values (illustrated in column 720 of FIG. 7) are now substituted for the market share correlator values. Finally, the values in columns 1060 and 1070 use the same inputs as columns 1020 and 1030, except that the cost reduction correlator values (illustrated in column 730 of FIG. 7) are substituted for the market share correlator values. (Since values for the cost reduction correlators are not provided, in the sample data shown in FIG. 7, the algorithm that computes values for columns 1060 and 1070 sets each result to 0.) In preferred embodiments, normalized values are computed for each of the sets (i.e., columns) of values in FIG. 10B by summing the values in each set and then dividing that sum by the number of values in the set. The normalized values for the sample data are shown in rows 1080 and 1090 of FIG. 10B. Turning next to FIG. 10C, a per-location score referred to herein as an “opportunity gap′” score is illustrated. In preferred embodiments, a set of opportunity gap numbers is computed by subtracting each geography profile value from the corresponding product profile value for each criteria that pertains to the marketplace (where these marketplace-related criteria are shown, by way of example, at reference numbers 420 and 430 in FIG. 4). In other words, these computations seek to evaluate the opportunity that may exist, within each of the candidate locations, for the product being assessed. Column 1100 in FIG. 10C shows the individual opportunity gap numbers for the candidate location “A” and column 1110 shows the numbers for candidate location “B”. Note that if there is no gap for a particular one of the criteria (i.e., the subtraction operation is not a positive number), its opportunity gap number is set to 0 in preferred embodiments. The values shown in columns 1100 and 1110 may be better understood by referring to the sample product profile 600 in FIG. 6 and the sample geography profiles 900, 910 in FIG. 9. The worldwide market opportunity value of 3 (see reference number 604 in FIG. 6) is subtracted from the location-specific market opportunity value of 5 (see reference number 902 in FIG. 9) for geography profile 900, resulting in an opportunity gap number of 2. In other words, this candidate location is perceived to have significant opportunities for the product being analyzed (as indicated by the opportunity value of 5), whereas the worldwide opportunity for that product is average (as indicated by the opportunity value of 3). The opportunity gap number of 2 that corresponds to this result is shown at reference number 1101 in FIG. 10C. Similarly, by subtracting the worldwide CGR value of 3 from the location-specific CGR value of 4 from geography profile 910, an opportunity gap number of 1 results. This value is shown at reference number 1111 in FIG. 10C. Once the opportunity gap numbers are computed for each candidate location, they are preferably summed to create the overall opportunity gap score for that location. This overall opportunity gap score can then be compared among the candidate locations. For the 3 sample marketplace-related skills criteria against which the two geography profiles 900, 910 of FIG. 9 were evaluated, the resulting opportunity gap scores are 4 and 2, respectively, thus indicating that candidate location “A” has a larger opportunity gap than candidate location “B”. See row 1230 of FIG. 10E, where the overall opportunity gap scores are presented. Several additional scores that may be generated will now be discussed. In preferred embodiments, the normalized values within each column shown in FIGS. 10B and 10D are summed, for each candidate location, and these results are shown in rows 1200, 1210, and 1220 of FIG. 10E. Thus, the value of 7.07 in column 1180 of row 1200 is the sum of normalized values 2.20 (from column 1020 of FIG. 10B), and from column 1120 of FIG. 10D, the values 0.67, 0.55, 2.20. and 1.45. The value of 6.37 in column 1190 of row 1200 represents the sum of normalized values from column 1030 of FIG. 10B and column 1130 of FIG. 10D. Since values in the columns 1020 and 1120, as well as 1030 and 1130, were created using the market share correlator values from column 710 of FIG. 7, the values in row 1200 therefore represent overall location-specific market share scores. Similarly, the value 8.99 in column 1180 of row 1210 is created by summing the normalized values from columns 1040 of FIGS. 10B and 1140 of FIG. 10D, and the value 7.83 in column 1190 of this row is created by summing the normalized values from columns 1050 of FIG. 10B and 1150 of FIG. 10D. These summed values were created using the revenue correlator values from column 720 of FIG. 7, and therefore the values in row 1210 represent overall location-specific revenue scores. Finally, the value 3.33 in column 1180 of row 1220 is created by sumnming the normalized values from columns 1060 of FIGS. 10B and 1160 of FIG. 10D, and the value 3.51 in column 1190 of this row is created by summing the normalized values from columns 1070 of FIGS. 10B and 1170 of FIG. 10D. These summed values were created using the cost reduction correlator values from column 730 of FIG. 7, and therefore the values in row 1220 represent overall location-specific cost reduction scores. The location-specific scores shown in FIG. 10E (which may be generally referred to as “resource placement scores”) may be analyzed in a number of ways to determine which candidate location should be selected as the optimal location for placement of human resources. Considering only the opportunity gap score, a large opportunity gap suggests that focus on that candidate location may be a high priority (and this may be true even when a different candidate location seems preferably if considering only the skills gap score). Taking another approach, a low overall skill gap score would be preferable for swiftly completing a development activity (or another activity that may be reflected with alternative choices for local skills 410). Considering both gap scores together, a high skill gap score combined with a high opportunity gap score would suggest that additional investment in increasing the skills in that location would benefit the company seeking to place its resources by capturing an increased amount of the unfulfilled opportunity. For the scores shown in rows 1200, 1210, and 1220 of FIG. 10E, a higher value indicates that this candidate location is preferable because of opportunity for improving market share, revenue, and cost considerations, respectively. Algorithms may be used, if desired, that manipulate a plurality of location-specific scores (such as those shown in FIG. 10E) to yield a single score per location (e.g., by weighting skills gap scores with opportunity gap scores and so forth). It may also be desirable, in some cases, to compute scores over subsets of the criteria, although this has not been illustrated herein. Block 820 of FIG. 8 stated that the computed scores will be presented to the user. This may comprise presenting all of the information shown in FIGS. 10A-10E, or some subset thereof, such as presenting only the scores from FIG. 10E. Optionally, techniques such as spider graph techniques may be used to overlay all of the scores on a single graph. Spider graphs, which are well known in the art (and are therefore not described herein in detail) enable organizing the scores by groupings of the assessment criteria (e.g., by the groups represented generally at 410, 420, 430, 440, 450, and 460 in FIG. 4), normalizing those values, and presenting the results graphically to allow the user to more readily compare alternatives. Scores computed using embodiments of the present invention may alternatively be used for purposes other than making an immediate decision as to placement of human resources. For example, if an assessment of candidate locations identifies skills that are consistently lacking, it may be desirable to make investments in one or more of these locations, such as providing funding to universities or providing equipment that is necessary for obtaining required practical experience, thereby proactively assisting the location(s) in closing the skills gap. Although a certain lag time will necessarily accrue before an actual improvement in available skills, the anticipated improvement may optionally be factored into a revised assessment of the location(s). As has been demonstrated, techniques disclosed herein provide novel ways of making decisions about resource placement, where marketing and growth opportunities are considered rather than simply seeking to minimize cost and expense. When an appropriate emerging market is identified as the optimal choice for resource placement, using comparisons and computations of the type which have been described herein, costs are typically reduced at the same time that revenues are increased, thereby providing an additional benefit to the company. Particular types of computations have been discussed herein with reference to the sample data that were used in describing operation of preferred embodiments. It should be noted that these computations are merely illustrative of the algorithmic manipulations that may be performed using techniques of preferred embodiments. It should be noted that the criteria that are important to resource placement decisions for a particular product, product family, or brand may change over time. In addition, the relative importance thereof may change. Therefore, embodiments of the present invention preferably provide flexibility in the assessment process and, in particular, in the criteria that are measured, in the values specified in a product profile, in how the measurements are weighted, and/or in how a product's assessment score is calculated using this information. Similarly, flexibility is preferably provided for updating geography profiles which may have been entered for candidate locations in order to reflect changed location-specific information. Furthermore, while preferred embodiments have been discussed with reference to evaluating at least two candidate locations, in order to select among those candidates, it may alternatively be advantageous to evaluate a single location (e.g., to determine how well this location meets a product's requirements). Or, a single location may be compared against benchmark values that represent (for example) a hypothetical location or a location in which resources for this product have already been placed. These alternative approaches are deemed to be within the scope of the present invention. Although preferred embodiments have been described as considering marketing and cost objectives being treated identically among the candidate locations, in alternative embodiments, objectives may be prioritized differently for different locations. For example, costs of the labor pool may vary significantly among the candidate locations: while a personnel cost criterion is depicted as having a single set of associated correlator values (see reference number 731 in FIG. 7), this criterion might be subdivided into more than one criteria, where different correlator values can then be assigned such that the personnel cost in each target location can be weighted differently, thereby allowing for further variations in the location-specific results. The disclosed techniques may also be used advantageously in methods of doing business. For example, these techniques may be used to provide a resource placement determination service, or to implement a third-party service whereby another company's resource placement decisions can be validated prior to implementation. Fees may optionally be charged for the assessments that are performed. Various revenue models may used for a fee-based service, such as pay-per-use billing, a subscription service, monthly or other periodic billing, and so forth. As will be appreciated by one of skill in the art, embodiments of techniques of the present invention may be provided as methods, systems, or computer program products. Accordingly, an implementation of techniques of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, an implementation of techniques of the present invention may take the form of a computer program product which is embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein. The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart and/or block diagram block or blocks. While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims shall be construed to include preferred embodiments and all such variations and modifications as fall within the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to expanding markets for products and services by making resource placement decisions in an objective manner, and deals more particularly with techniques for comparing one or more locations to a set of criteria that are directed toward identifying market strengths and weaknesses of the location(s) as part of an overall value chain. 2. Description of the Related Art Many countries or localities represent an untapped or an emerging market for the sale and adoption of information technology (“IT”). Often, these same countries are simultaneously experiencing a high growth rate in the availability of skills supportive of IT. Connections between a company's business and marketing strategy (and its related decisions) and its resource placement strategy (and its related decisions) may be revealed by examining and understanding the value chain in which the company participates. A value chain is defined as a sequence or network of transactions and mutually-beneficial relationships occurring between companies in the delivery of value to an end customer. Value chains have also been referred to as supply chains and value nets. Economists as far back as Adam Smith have described in great detail how value chains work, especially with regard to how such chains allow for and encourage specialization of business roles, and how they also drive more responsive business systems over time. As an example, consider a simple value chain that corresponds to a hardware supply chain, wherein a wholesale hardware manufacturer supplies a hardware product directly to a retailer who in turn sells it to an end customer. The hardware manufacturer receives value from the retailer because the retailer enables the manufacturer's products to reach the marketplace; this link in the value chain provided by the retailer supports and sustains further orders for the products provided by the manufacturer, thereby causing an increase not only in the manufacturer's revenue but also in the revenue of the retailer. The retailer receives value from the hardware manufacturer in terms of obtaining products that will meet needs of customers in this marketplace. The end customer receives value from the retailer, who provides the customer with an opportunity to buy the needed product, and in turn, the retailer receives value from the customer from the sale of the products. Other benefits may also result, such as increased market presence or brand awareness, and so forth. Symbiotic relationships thus exist between entities in the value chain. More complicated value chains, which may be recursive in some cases, are seen in the IT field. FIG. 1 illustrates representative entities in a sample IT-related value chain. A plurality of components 110 may be required in this particular chain, for example, and these components may be adapted for use with a plurality of operating systems 120 . In the more general case, a number of entities (see, for example, reference number 130 in FIG. 1 ) may be involved in creating one or more IT solutions 140 , which may be marketed through one or more distribution channels 150 . With these simple examples, it should be clear how companies become part of a value chain and also how they become dependent on both the upstream and downstream vitality and growth of other links in the chain. No company in a mature and free market is likely to own the entire chain of value. In fact, economists use the complexity of a value chain as one indicator of a market's (and a country's) economic maturity. It therefore follows that a company's ability to expand its market presence by delivering value to emerging and immature markets is influenced and limited by its ability to develop a rich and differentiated value net within these emerging markets. Accordingly, it is desirable to provide techniques that leverage a value chain analysis approach for determining optimal resource placement, particularly in emerging IT markets. | <SOH> SUMMARY OF THE INVENTION <EOH>An object of the present invention is to provide techniques for leveraging a value chain analysis approach to determine optimal resource placement in order to expand markets. Another object of the present invention is to provide techniques for determining optimal resource placement in emerging IT markets. A further object of the present invention is to make resource placement decisions using objective criteria. Another object of the present invention is to provide techniques for determining optimal resource placement decisions using business growth and marketing, rather than purely cost-oriented, objectives. Yet another object of the present invention is to objectively select among a plurality of candidate locations for resource placement. Another object of the present invention is to provide techniques for comparing labor localities using cost as well as marketing/growth criteria and objectives. A further object of the present invention is to provide techniques for presenting resource placement decision factors in a manner that improves acceptance and understanding of the placement decision by the overall work force and the marketplace. Other objects and advantages of the present invention will be set forth in part in the description and in the drawings which follow and, in part, will be obvious from the description or may be learned by practice of the invention. To achieve the foregoing objects, and in accordance with the purpose of the invention as broadly described herein, embodiments of the present invention may be provided as methods, systems, and/or computer program products. In one aspect, preferred embodiments comprise determining a company's business objectives, preferably in terms of candidate locations; developing objective measurements for those business objectives; performing value chain analyses for products/services to be provided by the company; deciding what types of human resources may improve the value chain; estimating and accounting for lag time characteristics, if any, that may be found in the value chain; developing cost factors, and bounds or limits on those factors, as appropriate; performing analyses that use the marketing factors as well as the cost factors; and assigning the human resources accordingly. This aspect is illustrative, but not limiting, of the scope of the present invention. The present invention may also be used advantageously in methods of doing business. For example, a company may provide a service for assessing products and candidate locations, thereby suggesting where the client should place its human resources. As another example, a company may implement a service whereby another company's resource placement decisions can be validated prior to implementation. When provided for a fee, a service of either type may be provided under various revenue models, such as pay-per-use billing, a subscription service, monthly or other periodic billing, and so forth. The present invention will now be described with reference to the following drawings, in which like reference numbers denote the same element throughout. | 20040331 | 20110607 | 20051006 | 74940.0 | 0 | ANDERSON, FOLASHADE | MARKET EXPANSION THROUGH OPTIMIZED RESOURCE PLACEMENT | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,683 | ACCEPTED | Method and system for sharing storage space on a computer | An application and method for transmitting copies of data to a remote back-up site for storage, and for retrieving copies of the previously stored data from the remote back-up site. A user designates files from an originating computer for which to transfer copies to a destination computer. The originating computer transfer designated data to portable computer readable medium for storage. The portable medium is physically delivered to the destination user. The destination user uploads the stored data to the destination computer. The destination computer authenticates the uploaded data. If the data is authenticated, the destination computer stores copies of the designated files. | 1. A method for facilitating the transfer of back-up copies of one or more files from a first computer to a second computer; comprising: designating files from the first computer for which back-up copies will be transferred to the second computer; selectively transferring the designated files and file data from the first computer to the second computer via a communication network or from the first computer to a portable computer readable medium based on a total size of the files being transferred; receiving, at the second computer, the selectively transferred files and file data, wherein said received file data includes authentication data for determining whether the first computer is authorized to store back-up copies on the second computer; and storing, at the second computer, the received files when the first computer is determined to be authorized. 2. The method of claim 1, wherein the designated files and file data are transferred from the first computer to a portable computer readable medium when the total size of the files to be transferred is greater than a target amount, said target amount defined by a user of the first computer. 3. The method of claim 2 further including: delivering the portable computer readable medium to a user of the destination computer; and transferring the files from the delivered portable computer readable medium to the second computer for storage. 4. The method of claim 1, wherein designating files includes displaying a first input form on a display linked to the first computer, said first input form receiving input data from a user, and said input data designating the one or more files to be copied and transferred to the portable computer readable medium. 5. The method of claim 1, wherein first transferring files include encrypting the designated files prior to transferring the designated files to the portable computer readable medium. 6. The method of claim 1 wherein transferring files includes transferring authentication data to the portable computer readable medium. 7. The method of claim 6, wherein the receiving includes retrieving first authentication data from the portable computer readable medium and retrieving second authentication data from the second computer, wherein said first authentication data defines a first password and said second authentication data defines a second password, and comparing the first password to the second password to determine if the passwords match, and wherein the one or more files are stored on the second computer if the first and second passwords are determined to match. 8. The method of claim 7 further including: retrieving, at the second computer, a first identification tag from the portable computer readable medium, said identification tag being randomly generated by the first computer to identify the one or more files to be transferred from the portable computer readable medium to the second computer; sending an authentication request including the first identification tag to the first computer via the communication network; receiving, at the first computer, the authentication request and the first identification tag; comparing, at the first computer, the received first identification tag with an second identification tag being stored on the originating computer to determine if the tags match, wherein the second identification tag corresponds to a tag previously generated by the first computer to identify a particular file or particular set files being transferred to a portable computer readable medium; requesting, at the first computer, input from an originating user to confirm back-up is authorized if there is a matching tag; sending a reply including the user input to the second computer via the communication network; and determining whether the first computer is authorized as a function of the user input included in the reply. 9. The method of claim 1 wherein storing files includes retrieving storage amount data and file storage data from a destination database, said storage amount data defining a maximum amount of storage space available on the second computer for storing files transferred from the first computer, and said file storage data specifying a current amount of storage space on the second computer being used for storing files from the first computer, and wherein storing files further comparing the storage amount data to file storage data to determine if storage space is available, and wherein the back-up copies of the one or more designated files stored on the portable computer readable medium are stored on the second computer if storage space is determined to be available. 10. The method of claim 1, wherein designating files for transfer further includes: designating a destination identifier associated with the second computer; designating storage schedule data for back-up copies; and storing the back-up copies of the designated one or more files, the designated destination identifier, and/or the designated storage schedule data in an originating database. 11. The method of claim 10, wherein designating files includes displaying a first input form on a display linked to the first computer, said first input form receiving input data from a user, and said input data designating the one or more files to be copied and transferred to the second computer, designating the one or more back-up times, and/or designating the destination identifier. 12. The method of claim 1 further comprising: retrieving one or more stored files from the second computer in response to a request received from the originating user; transferring the retrieved files to the portable computer medium; and delivering the portable computer medium to the originating user. 13. A method for facilitating the transfer of back-up copies of one or more files from a first computer to a second computer; comprising: designating files from the first computer for which back-up copies will be transferred to the second computer; identifying a location of the second computer; transferring the files from the verified first computer to a portable computer readable medium; selectively delivering the portable computer readable medium to a user of the destination computer based on an amount of data in the one or more files to be transferred, wherein the portable computer readable medium is physically delivered to the destination user when the amount of data to be transferred is greater than or equal to a target amount, and wherein the one or more files are transferred from the first computer to the second computer via a communication network when the amount of data to be transferred is less than the target amount. 14. The method of claim 13 wherein the originating user determines the target amount. | CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application No. 10/682,355; filed Oct. 9, 2003. FIELD OF THE INVENTION The invention relates to a system and method in which two or more users back-up computer files by agreeing to share storage space on the their computers. In particular, the invention relates to a system and method for selectively transferring encrypted copies of files from an originating computer to storage space on a destination computer. BACKGROUND OF THE INVENTION It is common practice for computer users to store computer file data on computer readable medium (CRM) such as CD-ROMs, digital versatile disks (DVD), magnetic cassettes, magnetic tape, magnetic disk storage, or magnetic hard disk drives. However, data stored on such storage devices can be lost due to fire, flood, theft, or any other event that adversely affects the storage medium. Therefore, it is often wise to generate a back-up copy of computer file data for storage at an off-site location in order to prevent destruction of both the original data and the back-up copy by the same catastrophic event. However, current methods of generating and maintaining back-up copies of file data are often inefficient. For example, some existing back-up operations involve creating a copy of all the data stored on the CRM. Although this method provides complete protection, it can be time consuming and can cause unnecessary wear on the mechanical components of the disk drive. Moreover, storage space could be saved at the back-up site by allowing the user at the origination site to designate one or more files for storage at a destination site. Some systems require physically transporting the storage medium containing the back-up copy to the back-up site. Such transportation may lead to further expense and opportunities for media damage. In addition, these prior methods do not provide an efficient system and method for retrieving the stored data from the off-site location. Moreover, prior online data storage systems are located at known sites on the Internet, and are therefore vulnerable to attack from malicious persons (i.e., hackers) attempting to access and/or modify data stored on such systems. In particular, these existing storage systems do not allow computer users to communicate with other computer users via a communication network, such as the Internet, for the purpose of storing back-up data on the other's computer. Thus, the need exists for a method and system for securely transmitting copies of data to a remote back-up site for storage, for retrieving copies of the previously stored data from the remote back-up site, and for verifying the transported data. A need also exists for a back-up system in which additional equipment is not required and one or more users share storage space on their computers. A need also exists to make it more difficult, if not impossible, for malicious users to identify a remote back-up site for particular users. SUMMARY OF THE INVENTION The invention meets the above needs and overcomes one or more deficiencies in the prior art by providing an improved application and method for securely transmitting copies of data to a remote back-up site for storage. In one embodiment, the invention utilizes an application that allows a user to predefine a schedule for automatically transmitting encrypted copies of files from an originating computer to a selected destination computer for storage. By predefining a schedule for transmitting encrypted copies of files to the destination computer, the invention allows encrypted copies of files to be transmitted without affecting user experience on either computer. In other words, the transfer of encrypted copies of files from the originating computer to the destination computer can occur automatically, and without the users of either computer being aware that the transfer is occurring. The features of the present invention described herein are less laborious and easier to implement than currently available techniques as well as being economically feasible and commercially practical In accordance with one aspect of the invention, a method is provided for facilitating the transfer of back-up copies of one or more files portable computer readable medium from a first computer to a second computer. The method includes designating files from the first computer for which back-up copies will be transferred to the second computer. The method includes transferring the files from the first computer to a portable computer readable medium. The method also includes delivering the portable computer readable medium to the destination user. The method further includes transferring the files from the delivered portable computer readable medium to the second computer for storage. In accordance with another aspect of the invention, a method is provided method for facilitating the transfer of back-up copies of one or more files from a first computer to a second computer. The method includes designating files from the first computer for which back-up copies will be transferred to the second computer. The method includes identifying a location of the second computer. The method includes transferring the files from first computer to a portable computer readable medium. The method includes selectively delivering the portable computer readable medium to a user of the destination computer based on a total size of the files being transferred. The portable computer readable medium is delivered to the destination user when the total size of the files is greater than or equal to a predetermined file size. The method includes selectively transferring the files from the first computer to the second computer via a communication network when the total size of the files is less than the predetermined file size. Alternatively, the invention may comprise various other methods and apparatuses. Other features will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a back-up system wherein copies of files stored on an originating computer are encrypted and transferred to a destination computer. FIG. 1A is a screen shot illustrating an exemplary validation form of the invention. FIG. 1B is a screen shot illustrating an exemplary destination identification form of the invention. FIG. 2 is a block diagram illustrating the components of an application that allows files stored on the originating computer to be retrieved, encrypted and transferred to the destination computer. FIG. 2A is a screen shot illustrating an exemplary file designation form of the invention. FIGS. 2B and 2C are screen shots illustrating an exemplary storage schedule forms of the invention. FIG. 2D is a screen shot illustrating an exemplary form for defining an encryption pass phrase. FIG. 2E is a screen shot illustrating an exemplary form for electing to retrieve a group of files or to retrieve individual files from storage. FIG. 3 is a block diagram illustrating the components of an application that allows encrypted copies of files stored on the destination computer to be transferred to an originating computer and decrypted. FIG. 3A is a screen shot illustrating an exemplary destination storage amount form of the invention. FIG. 3B is a screen shot illustrating an exemplary authentication form of the invention. FIG. 4 is an exemplary flow diagram illustrating a method for transferring copies of files from an originating computer to a destination computer according to one preferred embodiment of the invention. FIG. 5 is an exemplary flow diagram illustrating a method for retrieving back-up copies from a destination computer according to one preferred embodiment of the invention. FIG. 6 is a block diagram illustrating a back-up system wherein initial copies of files stored on an originating computer are encrypted and stored on a portable medium for manual transfer to a destination computer. FIG. 7 is an exemplary flow chart illustrating a method for transferring back-up copies of one or more files from the originating computer to a portable storage medium for delivery to the destination user. FIG. 8 is an exemplary flow chart illustrates a method for verifying that the originating user desires to transfer back-up copies of one or more files from the originating computer to a portable storage medium for delivery to the destination user. Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1, an exemplary block diagram illustrates a back-up system 100 for transferring copies of files from an originating computer 102 to a destination computer 104. The originating computer 102 and destination computer 104 are coupled to a data communication network 106 such as the Internet (or the World Wide Web) to allow the originating computer 102 and destination computer 104 to communicate. In the example of FIG. 1, the invention employs an application that allows a user to designate files from the originating computer for which back-up copies will be transferred to the destination computer 104, and allows the originating computer 102 to retrieve back-up files from the destination computer 104. The application of the invention also allows the originating computer to receive back-up copies of files from the destination computer 104. The originating computer 102 is linked to an originating computer-readable medium (CRM) 112. The originating CRM 112 contains an originating application 114, and stores one or more files 116. An originating user 118, using an originating user-interface (UI) 120 linked to the originating computer 102 designates one or more files 116 stored on the originating CRM 112 for which to transfer copies to a destination CRM 122 for storage. For example, the UI 120 may include a display 124 such as a computer monitor for viewing forms requesting input from the user, and an input device 126 such as a keyboard or a pointing device (e.g., a mouse, trackball, pen, or touch pad) for entering data into such an input form. The destination computer 104 is linked to a destination CRM 122. The destination CRM 122 contains a destination application 115, and may store one or more encrypted files 128 previously transferred from the originating CRM 112. A destination user 130 using a destination UI 132 linked to the destination computer 104 allocates the originating user 118 an amount of storage space on the destination CRM 122. For example, after the destination user 130 has agreed to become a storage partner with the originating user 118, the destination user 130 use an input device 135 to enter data into an input form being displayed on the destination display 134 to allocate the originating user 118 10 megabytes of storage space on the destination CRM. Alternatively, the destination user 130 may allocate the originating user 118 all of the storage space on the destination CRM 122 (e.g., an entire hard drive). Notably, the originating application 114 and the destination application 115 are the same application. In other words, the application of the invention possesses dual functionality to allow the same application to be used on both the originating computer 102 and the destination computer 104. In one embodiment, a front end server (server) 108, also referred to as “web server” or “network server,” is also coupled to the communication network 106, and allows communication between the server 108 and the originating computer 102, and between the server 108 and the destination computer 104. In this example, the originating computer 102 and the destination computer 104 download the originating application 114 and destination application 115, respectively, from the server 108 using the File Transfer Protocol (FTP). However, the application of the invention can also be obtained through any other commercial transaction. The originating computer 102 and the destination computer 104 can also retrieve identification data from the server 108 using the Hypertext Transfer Protocol (HTTP). As known to those skilled in the art, FTP is a protocol commonly used on the Internet to exchange copying and/or transferring files to and from remote computer systems, and HTTP is a protocol commonly used on the Internet to exchange information. As described in more detail below, identification data includes an application identification code and an Internet protocol address associated with a particular computer. The server 108 is coupled to a back-up database 131 that store identification data. For example, the back-up database 131 contains an Internet Protocol (IP) address and unique application identification code (ID) for each of the originating and destination computers. As known to those skilled in the art, the IP address uniquely identifies a computer when it is connected to the Internet via an Internet Service Provider (ISP). In one embodiment, after a user loads the application of the invention for use on a particular computer by downloading or other copying, the server 108 emails the user an application ID. The user then submits the application ID back to the server 108 via a validation form 140 such as illustrated in FIG. 1A to validate the application, and to associate the submitted application ID with the particular computer to which the application was downloaded. During this initial communication session, or any subsequent communication session, between computer and the server 108, the server 108 records and stores the IP address of the computer submitting the application ID in the back-up database 131. The server 108 also executes an assigning routine 133 to assign the submitted application ID to the computer from which the application ID was submitted. Thereafter, the application ID and corresponding IP address associated with that particular computer are maintained in the server database 131. As a result, the server 108 can be used to obtain an IP address associated with the destination computer 104. For example, the originating user 118 submits the destination ID to the server 108 via an identification form 142 such as shown in FIG. 1B to identify the IP address of the destination computer 104. The server 108 executes an identification program 136 to verify that the submitted application ID is valid, and then queries the server database 131 to identify the last known IP address associated with destination computer 104. As described below in FIG. 2, the destination ID and corresponding IP address are also maintained in the originating computer 102. Moreover, the server 108 obtains the IP address of the originating computer 102 when the originating user is requesting the IP address of an existing partner. As known to those skilled in the art, ISP providers frequently change the IP address assigned to a particular computer. As a result, the originating computer 102 may not be able to establish a connection with the destination computer 104. To verify that the originating computer 102 has the correct IP address stored for the destination computer 104, the originating user 118 contacts the server 108 in order to obtain the last known IP address of the existing partner's computer. During this subsequent communications session between the originating computer 102 and the server 108, the server 108 again obtains and stores the IP address of the originating computer 102. Likewise, if the destination user 130 has sent a similar IP request to the server 108 for any computer sharing space with destination computer 104, the server 108 will also have the IP address of the destination computer at the time the IP request was made. Thus, the originating computer 102 can obtain the latest known IP address of the destination computer 104 from the server 108, and can attempt to establish a communication session with the destination computer 104 via the latest known IP address. Notably, the server 108 is optional, as indicated by reference character 150, and is not necessary component of the back-up system 100 for transferring files between the origination and destination computers. In other words, if the originating computer 102 has the IP address of the destination computer stored in memory (e.g., originating database 204), the originating computer 102 can communicate directly with the destination computer, and there is no need to communicate with the server 108. Referring now to FIG. 2, a block diagram illustrates the components of a originating application 114 that allows files 202 (e.g., files 116) stored on the originating computer 102 to be designated, encrypted, and transferred to the destination computer 104 according to one preferred embodiment of the invention. In this embodiment, the origination application 114 uses an originating database 204 and an originating program 206 to transfer copies of files 202 from the originating computer 102 to the destination computer 104. The originating database 204 stores file designation data 208, destination identification (ID) data 210, and storage schedule data 212, and authentication data 213. The originating program 206 includes originating designating instructions 214 for designating files to back-up (i.e., copy to destination computer), identifying instructions 218 for identifying the destination computer, and transferring instructions 220 for transferring the encrypted files 202 to the destination computer. Originating designating instructions 214 include instructions for displaying a file transfer designation form 215 such as shown in FIG. 2A on the display 124. In this case, the file designation transfer form 215 allows the originating user 118 to select one or more file extensions (e.g., .txt, .doc, etc.). This allows the user to designate all files from the originating CRM 216 (e.g. CRM 112) having the one or more selected file extensions for copying to the destination computer 104. In alternate embodiment (not shown), the user selects files from a list files (e.g., file list box showing files on computer), or the user uses a keyboard to type a specific file name. The files 202 designated by the user are stored as file designation data 208 in the originating database 204. Originating designation instructions 214 also include instructions for displaying a storage schedule form 217, 219 such as shown in FIGS. 2B and 2C, respectively, to the user on the display 124. The storage schedule form 217 allows the user to designate storage schedule data 212. The storage schedule data 212 identifies one or more back-up times for transferring copies of designated files from the originating CRM 216 to the destination computer. For example, the originating user 118 uses the originating UI 120 to enter a specific time(s) of day, or time interval into the storage schedule form 217 to define a personal back-up schedule for one or more files designated for back-up on a particular destination computer 104. Importantly, it is not necessary to communicate to the partner the content, the subject matter, or any information about the files. Identifying instructions 218 include instructions for displaying the destination identification form 142 (see FIG. 1B). The destination identification form 142 allows the user to identify the particular destination computer 104 to which to transfer copies the designated files. In this case, a “partner” (i.e., user of a particular destination computer) is identified and added to the originating database 204 by entering the unique application ID (i.e., destination ID) that corresponds to the particular originating application 114 stored on the destination computer 104. The originating user 118 obtains the application ID corresponding to the particular destination computer 104 (i.e., destination ID) by communicating (e.g., verbal communication, email, etc.) with the partner (i.e., destination user). As described above, the destination ID is a unique identification code assigned to the destination computer 104 when the originating application 114 is purchased or downloaded from the server 108. The destination ID provides access to the corresponding IP address of the destination computer 104 through a lookup function executed against the back-up database 131 maintained by the server (i.e., server database) or a third party. Originating transferring instructions 220 include instructions for initiating a communication session with the destination computer 104 in response to input received from a user 118 to transfer copies of the designated files to the destination computer 104. Originating transferring instructions 220 also include instructions for encrypting the copies of the designating files prior to transferring copies to the destination computer 104. In one embodiment, the originating application 114 utilizes a Triple Data Encryption Standard (3DES) to secure (i.e., encrypt) the contents of the files prior to transfer. Before encryption instructions can be executed, the user must first supply a pass phrase via an encryption validation form 221 (see FIG. 2D) that is then cryptographically hashed and stored in the user's registry. Thereafter, the hashed pass phrase is used to encrypt and decrypt files stored on partners' computers. If the pass phrase is lost and cannot be remembered, the files stored remotely cannot be decrypted. After the files have been encrypted, the transfer instructions 200 execute and read destination ID data 210 in the originating database 204 to identify the destination computer 104, and then transfers the encrypted copies of the designated files to the identified destination computer 104. Once stored on the destination computer 104, the encrypted files 128 are meaningless to the partner. Even the file names are “hash codes” that are only meaningful to originating computer. In other words, the partner cannot discern the content or names of the files that have been stored on the destination computer by the originating user. Although encrypting the files is not necessary, if encryption is not used, files stored on a given partner's computer may possibly be viewed with a hex editor or other utility. Originating transferring instructions 220 also include instructions for automatically initiating a communication session with the destination computer 104 in response to storage schedule data. For example, after the originating user 118 assigns a schedule to a particular destination computer's (i.e., partner's) configuration, the originating computer 102 initiates a communication session with the destination computer 104 to transfer encrypted copies of the designated files. Thereafter, back up can occur automatically at the back-up time(s) specified in the storage schedule data. In one embodiment, automatic back-up only occurs on files that have been changed. Importantly, automatic back-up allows the transfer of encrypted copies of files 202 from the originating computer 102 to the destination computer 104 to take place without the users of computers 102, 104 being aware that the transfer is occurring. The originating program 206 also includes destination-designating instructions 222 for designating files to retrieve from the destination computer 102, and retrieving instructions 224 for retrieving the designated files from the destination computer 104. Destination designating instructions 222 include instructions for displaying a file retrieval form 225 (see FIG. 2E) to allow the user to retrieve a group of files or individual files. File retrieval designation forms (not shown) are similar to file transfer designation forms. More specifically, the user can designate a group of files (e.g., files having the same file type extension) for retrieval (e.g., FIG. 2A), or the user can particular files by file name. The files entered or selected by the user 118 are then stored as destination file designation data 226 in the originating database 204. Retrieving instructions 224 use the previously identified IP address associated with the particular application ID of the destination computer 104 to initiate a communication session between the originating computer 102 and the destination computer 104 to retrieve the designated files from the destination computer. As described above in reference to FIG. 1, if the IP address of the destination computer has changed, the originating application 114 can contact the server 108 and submit the previously obtained destination ID of the destination computer 104 to query the server's database 131 for the latest IP address of the destination computer 104. The server 108 not only delivers the last known IP address of the desired application ID, but also stores the IP address of the computer submitting the application ID. In this way, the server 108 maintains the latest IP address for that particular computer in the server database 131. In one preferred embodiment, the retrieving instructions 224 further include instructions for decrypting retrieved encrypted files. The originating application 114 can also utilize the Triple Data Encryption Standard (3DES) to decrypt the contents of the encrypted files. Receiving instructions 226 include instructions for initiating a communication session with the destination computer 104 in response to a transfer request received from the destination computer 104 to transfer copies of the designated files on the destination computer 104 to the originating computer. Referring now to FIG. 3, a block diagram illustrates components of a destination application 115 allowing encrypted copies of files 302 received from an originating computer 102 to be stored on the destination computer 104. In this embodiment, the destination application 115 uses a destination database 304, and a destination program 306 to store of back-up copies of files from the originating computer 102 onto the destination computer 104. The destination database 304 includes file storage data 308, storage amount data 310, and authentication data 312. File storage data 308 identifies encrypted files and/or post-transfer data regarding files received from the originating computer 102 and stored on the destination CRM 314 (e.g., CRM 122). For instance, post-transfer data includes the total amount of disk space currently being used to store back-up copies of files from the originating computer. The storage amount data 310 identifies an amount of storage space (i.e., disk space) on the destination CRM 314 that the destination user 130 has authorized for use by the originating user 118. The destination user 130 can allocate the originating user 118 a few megabytes or an entire hard drive of storage space on the destination computer 104. For example, the destination user 130 uses a storage amount form 315 such as shown in FIG. 3A to enter an amount of storage space that has been mutually agreed upon by both users 118, 130. The authentication data 312 includes authentication information used to verify that the originating user 118 is authorized to store files on the destination computer 104, and/or retrieve files from the destination computer 104. The destination program 306 includes file storage instructions 316, authentication instructions 318, and transferring instructions. The destination program 306 can be executed by the destination user 130, or by the originating program 206. For instance, the destination user 130 executes the storage instructions 316 to define and authorize a maximum amount of storage space on the destination CRM 314 for storing files from the originating computer 102. In another embodiment, the storage instructions 316 include instructions for determining whether sufficient storage space is available on the destination CRM 314 to store copies of files from the originating computer 102. For example, upon execution, the storage instructions retrieve file storage data 308 identifying the amount of disk space currently being used to store copies of files from the originating computer 102 (e.g., post transfer data). The storage instructions 316 then compare the storage amount data 310 defined by the destination user 130 to the file storage data 308 to determine if storage space is available. If sufficient storage space is available, the one or more files are stored on the destination CRM 314. If sufficient storage space is not available, the storage instructions 316 display a message on the originating display that informs the originating user that there is insufficient storage space. The originating user 118 executes the destination program 306 by executing the retrieval instructions 224. As discussed above in reference to FIG. 2, when the retrieving instructions 224 are executed, a communication link is established between the destination and originating computers to selectively retrieve one or more encrypted files. After the communication link is established, the retrieving instructions 224 read the destination file storage data 226 from the originating database 206, and retrieve one or more encrypted files from the destination CRM 314. Thereafter, the destination transferring instructions 320 transfers the designated encrypted files to the originating computer 102. Authentication instructions 318 include instructions for determining whether the originating user 118 is authorized to store files on the destination CRM 314, and/or is authorized to retrieve files from the destination CRM 314. For example, when the originating computer 102 contacts the destination computer 104 for a communication session, the destination computer 104 executes authentication instructions 318. The authentication instructions 318 include instructions for retrieving previously defined authentication data such as a password. For example, after the originating user 118 and destination user 130 have agreed to become storage partners, they each define a mutually agreed pass phrase to store as authentication data in the originating database 204 and destination database 304, respectively. In one embodiment, an authentication form 321 such as shown in FIG. 3B is used by both users 118, 130 to enter the mutually agreed upon password. The authentication instructions 318 also include instructions for comparing the authentication data 213 stored in the originating database 204 to the authentication data 314 stored in the destination database 304. If the authentication data 213 stored in the originating database matches the authentication data 314 stored in the destination database 304, the originating application 114 is allowed to access the destination CRM 314 for file storage and/or file retrieval. By comparing the predefined authentication data, the user 118 is not required to enter a password during future back-up session between the originating computer 102 and the destination computer 104. Referring now to FIG. 4, a flow chart illustrates a method for transferring back-up copies of one or more files from the originating computer 102 to the destination computer 104. At 402, the user uses UI 118 to designate files from the originating computer 102 for which to transfer copies to the destination computer 104. At an optional step 404, the user uses the UI 118 to define file parameter data for the designated files. For instance, the user may use the UI 118 to define back up schedule data. Back up schedule data includes specific times and/or intervals for transferring the designated files. As described above, authentication data may include a password, or pass phrase, that has been mutually agreed upon between partners. At 405, the user uses UI 118 to define identification data to identify the destination computer. Identification data includes a unique application ID (i.e., destination ID) that corresponds to the particular destination application 115 stored on the destination computer. At 406, the originating application 114 uses the identification data to determine the location of the destination computer 104. As described above, the destination ID provides access to the corresponding IP address of the destination computer 104 through a lookup function executed against the database 131 maintained by the server. At 408, the user uses the UI to define whether the transfer of back-up copies to the destination computer initiates manually or automatically. The originating application 114 determines whether the user has defined the transfer of back-up copies to occur manually or automatically at 409. If the application determines the transfer of back-up copies is defined to occur manually at 409, the originating application 114 waits for the user to initiate a transfer request at 410. For example, the user uses a mouse to click a transfer button on a form (not shown) being displayed to the user via the display, and the originating computer request a communication session with destination computer having the identified IP address. The destination application 115 receives the transfer request at 411. At 412, the destination application 115 authenticates the transfer request to determine whether the originating computer is authorized to transfer files to the destination computer 104 for storage. As an example, authentication may involve comparing authentication data received from the originating computer along with the transfer request to authentication data stored on the destination computer 104. As described above in reference to FIG. 2, authentication data includes a password previously defined by users 118, 130 and stored in the originating database 204 and destination database 304, respectively. If authentication data from the originating computer 102 does not match the authentication data stored on the destination computer 104, the originating computer 102 is not authenticated at 412, and the destination application 115 alerts the user that the password is invalid at 413. If the entered password matches the authentication data stored on the destination computer 104, the originating user is authenticated at 412. In one embodiment, after the destination computer 104 receives a transfer request from the originating computer 102, the destination computer 104 generates a random number and sends it to the originating computer 104. The originating computer 102 performs a one-way hash function on the random number and the locally-stored password and sends the result back. The destination computer then computes the same function and compares the results. In this way, the originating computer can be authenticated without revealing the password. As known to those skilled in the art, a one way hash function is used to generate a cryptographically-secure message, and is a function that is easy to compute in the forward direction, but computationally infeasible to invert. After the originating computer is authenticated, the destination computer determines whether sufficient storage space is available for storing back-up copies at 414. For example, the destination compares the amount disk space required for storing the back-up copies to storage amount data defining an amount of disk space the destination user has allocated to the particular originating user. If sufficient storage space is determined available at 414, the back-up copies are stored on the destination computer at 416. If sufficient storage space is determined not available at 414, the originating user is alerted that there is insufficient storage space at 418. If the application determines the transfer of back-up copies is defined to occur automatically at 409, the originating computer retrieves storage schedule data and authentication data, and automatically initiates a transfer request for transferring back-up copies of the designated files to the identified destination computer at the times defined by the storage schedule data at 419. The destination application 115 receives the transfer request at 420. At 422, the destination application 115 authenticates the transfer request to determine whether the originating computer 102 is authorized to transfer files to the destination computer for storage. Again, authentication may involve comparing authentication data stored on the originating computer 102 to authentication data stored on the destination computer 104. If the authentication data stored on the originating computer 102 does not match the authentication data stored on the destination computer 104, the originating computer is not authenticated at 422, and the destination application 115 alerts the user that the password is invalid at 424. If the authentication data stored on the originating computer 102 matches the authentication data stored on destination computer 104, the originating computer is authenticated at 420, and the destination application 115 determines whether sufficient storage space for storing back-up copies is available at 426. If sufficient storage space is available, the back-up copies are encrypted and stored on the destination computer at 428. If sufficient storage space is not available, the originating user is alerted that there is insufficient storage space at 430. Referring now to FIG. 5, a flow chart illustrates a method for transferring back-up copies of one or more files from the destination computer 104 to the originating computer 102. At 502, the user uses UI 124 to designate files (e.g., back-up copies) to retrieve from the destination computer 104. At 504, the originating application 114 retrieves identification data stored in the originating database 108 to determine the location (i.e., IP address) of the destination computer 104, and submits a retrieval request to the identified destination computer 104 via the communication network. The destination application 115 receives the retrieval request for the designated files at 506. At 508, the destination application 115 authenticates the retrieval request. For example, authentication data stored on destination computer is compared to authentication data submitted from the originating computer along with the retrieval request. If the authentication data received from the originating computer 102 is determined to match authentication data stored on destination computer 104, the user is authenticated at 508, and the destination application 115 transfers the requested files to the originating computer for decryption at 510. If the authentication data received from the originating computer 102 is determined not to match authentication data stored on destination computer 104 the user is not authenticated at 508, and the user is alerted of that the authentication process has failed at 512. Referring now to FIG. 6, a block diagram illustrates a back-up system 600 wherein copies of files stored on an originating computer are encrypted and stored on a portable medium for manual transfer to a destination computer. As known to those skilled in the art, regardless of the connection type (e.g., broadband, dial-up, etc.) there are limits to the rate at which data can be transferred over communication networks such as the Internet. As a result, when the originating user 118 transfers large amounts of data (e.g., file data of 1 Gigabyte (GB) or more) to the destination computer 104 for back-upback-up, the transfer may require several hours. Although the back-upback-up stream system 100 allows data transfer to occur without the knowledge of destination user 130, due to the amount of time required for transferring large amounts of data, such transfers are more likely to be interrupted, for example, by a network time-out, or power interruption to either the originating computer 102 or the destination computer 104. In this embodiment, rather than transferring designated files directly to the destination computer 104 via the network 106, the originating user 118 initially transfers the designated files to a portable computer readable medium (portable medium) 602 such as zip drive, tape, Compact Disc (CD) or Digital Versatile Disk (DVD). For example, if the user desires to back-up files having a total file size that exceed 1 GB, the user may decide to transfer the files via a portable medium due to a previous experience (e.g., network time out) while backing up files of similar size. In such a case, prior to transferring copies of the designated files to the portable medium 602, the originating application 114 executes originating transferring instructions 220, as described above in reference to FIG. 2, to encrypt copies of the designating files. Thereafter, the originating user 118 delivers the portable medium 602 having the encrypted file data to the storage partner (i.e., destination user 130), and the destination user 130 uploads or transfers the encrypted files from the portable medium 602 to the destination CRM 112. The delivery, as indicated by reference character 604, takes place, for example, via mail, courier service, or some other manual means of physically transporting the medium 602 from first a geographical location to a second geographical location. The transfer instructions 200 also transfer authentication data from the originating computer 102 to the portable medium 602. Again, as described above in reference to FIG. 3, the authentication data 312 includes authentication information used to verify that the originating user 118 is authorized to store files on the destination computer 104, and/or retrieve files from the destination computer 104. After the destination user 130 receives the portable medium 602, as indicated by phantom lines, the user 130 initiates transfer of the files stored on the portable medium 602 to the destination computer 130. As shown in FIG. 3, the destination application 114 includes file storage instructions 316. In this embodiment, the file storage instructions 316 include instructions for determining whether sufficient storage space is available on the destination CRM 314 to store copies of files stored on portable medium 602. The storage instructions 316 then compare the storage amount data 310 defined by the destination user 130 to the file storage data 308 to determine if storage space is available. If sufficient storage space is available, the one or more files are stored on the destination CRM 314. If sufficient storage space is not available, the storage instructions 316 display a message on the destination computer display to inform the destination user 130 that there is insufficient storage space. In response to such a message, the destination user 130 can allocate more storage space, as described above in reference to FIG. 3, or discontinue the transfer process and notify the originating user 118 that his or her storage capacity has been reached. As described above in reference to FIG. 3, the destination application includes authentication instructions 318 for comparing the authentication data 213 stored in the originating database 204 to the authentication data 312 stored in the destination database 304. In this embodiment, authentication instructions 318 compare authentication data 312 transferred to the portable medium 602 from the originating computer 102 to the authentication data stored in the destination database 304. If the authentication data 213 stored in the originating database 204 matches the authentication data 314 stored in the destination database 304, the originating user 118 is authenticated to access the destination CRM 314 for file storage. By comparing the predefined authentication data, imposters or non-storage partners are prevented from tricking an unsuspecting destination user 130 into transferring unauthorized data onto the destination computer 104. Notably, when authentication data such as the mutually agreed upon passphrase is transferred to the portable computer readable medium, the method of delivery should be secured and/or trusted. If the method of delivery is not secure, the portable medium 602 could be lost or stolen, and thereby potentially recoverable by a malicious user. In another preferred embodiment, after the originating user 118 elects to store data on a portable computer readable medium 602, the originating application 114 generates a unique identification tag (ID tag) 605. The ID tag 605 is used to identify a particular file or group of files being transferred to the portable computer readable medium at a particular time. In this embodiment, the ID tag 605 includes a randomly generated set of numbers and/or characters (e.g., key), and volume identification data. For example, a randomly generated alphanumeric value “AA0121” corresponds to a set of files the originating user transferred to the portable computer readable medium on Monday, Mar. 2, 2004, and the alphanumeric value “AB0132” corresponds to a next set of files that the originating user transferred to the portable computer readable medium on Mar. 20, 2004. Volume identification data identifies, a particular version of file data being transferred. The originating application 114 stores the ID tag 605 in the originating database 204 of the originating computer 102, and the transferring instructions 220 transfer the ID tag 605, to the portable computer readable medium 602 for storage. As described above, after the destination user 130 initiates transfer of the files and file data, including the ID tag 605 from the portable medium 602 to the destination computer 130, the destination application 115 executes the authentication instructions 318. In this embodiment, the authentication instructions 318 include instructions for verifying that the originating user 118 desires to back-up the one or more files identified by the ID tag 605. More specifically, the authentication instructions 318 use the previously identified IP address associated with the particular application ID of the originating computer 102 to initiate a communication session, via the communication network 106, between the originating computer 102 and the destination computer 104. As described above, the application ID is a unique identification code assigned to the originating computer 102 when the originating application 114 is purchased or downloaded from the server 10, and provides access to the corresponding IP address of the originating computer 102 through a lookup function executed against the back-up database 131 maintained by the server (i.e., server database) or a third party. The authentication instructions 318 send the ID tag 605 obtained from the portable medium 602 back to the alleged originating computer 102 via the network 106, which then sends a reply back to the destination computer 104 via the network 106 either allowing the file copy transaction to occur or not to occur. The originating application 114 is responsive to the received ID tag 605 to query the originating database 204 for that particular ID tag 605. If the ID tag 605 is found, the originating application 114 displays, for example, a dialog box (not shown) on the display of the originating computer 102 listing the one or more files associated with the ID tag 605, and presents a message to the originating user 118 such as “ARE THES FILES AUTHORIZED FOR BACK-UP.”. For example, if the user desires to proceed with back-up, the user 118 left clicks a “Yes” button in the dialog box, and a reply is sent to the destination computer 104 that the files are authorized for back-up. If the ID tag 605 is not found, or the user 118 does not wish to proceed with back-up (e.g., left clicks a “No” button in the dialog box), the originating application 114 sends a reply back to the destination computer 102, via the network 106, that the files are not authorized for back-up. This allows the originating user 118 to verify that the proper data set is attempting to be loaded on the destination computer. Moreover, this prevents the destination user 130 from maliciously or accidentally waiting a period of time (e.g., week, month, etc.) and transferring the data again, thereby potentially overwriting back-up data stored during the interim. In another embodiment (not shown), the key portion (i.e., randomly generated number) of the ID tag 605 is used in a symmetric key encryption process to encrypt the contents of entire disc, and destination computer initiates a communication session with the originating computer 102 to requests the tag. In turn, the originating computer could either deny it (e.g., expired) or provide it, which would then allow the disc load to proceed. Subsequent transfer of smaller data amounts can be transferred via the communication network, such as described above in reference to FIGS. 1-5. Moreover, transferring large amounts of data manually essentially jump-starts the transfer of smaller amounts of data over the communication network 106. In other words, small increments of data can be transferred in less time. In the event the originating user 118 loses significant amounts of data, the destination user 130 (i.e., storage partner) could transfer copies of encrypted files to the portable medium 602 and deliver it the originating user 118. Notably, although the destination user 130 can transfer data to or from the portable medium 602, the partner (i.e., destination user) cannot discern the content or names of the files that have been stored on the portable medium 602 by the originating user. Referring now to FIG. 7, a flow chart illustrates a method for transferring back-up copies of one or more files from the originating computer 102 to a portable storage medium for delivery to the destination user. At 702, the originating user uses UI 120 to designate files (e.g., back-up copies) to transfer to a portable medium such as a CD. The originating application encrypts the designated files at 704. At 706, the encrypted files are transferred to the portable medium for storage. The portable medium is delivered to the destination user at 708. For example, the originating user sends the portable medium to the destination user via the United States Postal Service. At 710, the destination user executes storage instructions to upload the encrypted data stored on the portable medium to the destination computer for storage. The storage instructions determine whether sufficient storage space is available on the destination computer for storing the encrypted files stored on the portable medium at 712. If sufficient storage space is not available, the destination user is alerted that there is insufficient storage space at 714. If sufficient storage space is determined to be available at 712, the destination computer 104 executes authenticating instructions at 716 to authenticate (i.e., verify) that the originating computer 102 is authorized to store data on destination computer 104. As described above in reference to FIG. 2 and FIG. 4, authentication data includes a password previously defined by users 118, 130 and stored in the originating database 204 and destination database 304, respectively. If authentication data from the originating computer 102 does not match the authentication data stored on the destination computer 104, the originating computer 102 is not authenticated at 717, and the destination application 115 alerts the user 130 that the originating computer 102 is not authorized to store data at 718. If the entered password matches the authentication data stored on the destination computer 104, the originating computer 102 is authenticated at 717, and the encrypted files are transferred and stored on the destination computer at 720. Referring now to FIG. 8, a flow chart illustrates an additional method for authenticating that the originating user 118 desires to transfer back-up copies of one or more files from the originating computer 102 to a portable storage medium for delivery to the destination user. In addition to password authentication data, authentication data includes ID tag data. As described above in reference to FIG. 6, an ID tag 605 is stored in the originating database 204 of the originating computer and stored on the portable computer readable medium 602. In this case, after the destination user 130 executes storage instructions to upload the encrypted data stored on the portable medium 602 to the destination computer 104 for storage, the destination application 115 executes authentication instructions (See FIG. 7). At 802, the destination application 115 retrieves identification data stored on the portable computer readable medium 602 to determine the location (i.e., IP address) of the originating computer 102. The destination computer 104 submits an authentication request, which includes the ID tag 605, to the identified originating computer 104 via the communication network at 803. At 804, the originating computer 114 is responsive to the received ID tag 605 to query the originating database 204 for that particular ID tag 605. If the ID tag 605 is found at 806, the originating application 114 prompts the originating user 118 to confirm that back-up of the listed files is desired at 808. If the user 118 confirms that back-up of the listed files is desired at 808, the originating application 114 sends a reply back to the destination computer 104 via the network 106 that the files are authorized for back-up at 810. If the ID tag 605 is not found at 806, or the user 118 does not confirm that back-up of the listed files is desired at 808, the originating application 114 sends a reply back to the destination computer 104 via the network 106 that the files are not authorized for back-up at 810. As various changes could be made in the above products and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. | <SOH> BACKGROUND OF THE INVENTION <EOH>It is common practice for computer users to store computer file data on computer readable medium (CRM) such as CD-ROMs, digital versatile disks (DVD), magnetic cassettes, magnetic tape, magnetic disk storage, or magnetic hard disk drives. However, data stored on such storage devices can be lost due to fire, flood, theft, or any other event that adversely affects the storage medium. Therefore, it is often wise to generate a back-up copy of computer file data for storage at an off-site location in order to prevent destruction of both the original data and the back-up copy by the same catastrophic event. However, current methods of generating and maintaining back-up copies of file data are often inefficient. For example, some existing back-up operations involve creating a copy of all the data stored on the CRM. Although this method provides complete protection, it can be time consuming and can cause unnecessary wear on the mechanical components of the disk drive. Moreover, storage space could be saved at the back-up site by allowing the user at the origination site to designate one or more files for storage at a destination site. Some systems require physically transporting the storage medium containing the back-up copy to the back-up site. Such transportation may lead to further expense and opportunities for media damage. In addition, these prior methods do not provide an efficient system and method for retrieving the stored data from the off-site location. Moreover, prior online data storage systems are located at known sites on the Internet, and are therefore vulnerable to attack from malicious persons (i.e., hackers) attempting to access and/or modify data stored on such systems. In particular, these existing storage systems do not allow computer users to communicate with other computer users via a communication network, such as the Internet, for the purpose of storing back-up data on the other's computer. Thus, the need exists for a method and system for securely transmitting copies of data to a remote back-up site for storage, for retrieving copies of the previously stored data from the remote back-up site, and for verifying the transported data. A need also exists for a back-up system in which additional equipment is not required and one or more users share storage space on their computers. A need also exists to make it more difficult, if not impossible, for malicious users to identify a remote back-up site for particular users. | <SOH> SUMMARY OF THE INVENTION <EOH>The invention meets the above needs and overcomes one or more deficiencies in the prior art by providing an improved application and method for securely transmitting copies of data to a remote back-up site for storage. In one embodiment, the invention utilizes an application that allows a user to predefine a schedule for automatically transmitting encrypted copies of files from an originating computer to a selected destination computer for storage. By predefining a schedule for transmitting encrypted copies of files to the destination computer, the invention allows encrypted copies of files to be transmitted without affecting user experience on either computer. In other words, the transfer of encrypted copies of files from the originating computer to the destination computer can occur automatically, and without the users of either computer being aware that the transfer is occurring. The features of the present invention described herein are less laborious and easier to implement than currently available techniques as well as being economically feasible and commercially practical In accordance with one aspect of the invention, a method is provided for facilitating the transfer of back-up copies of one or more files portable computer readable medium from a first computer to a second computer. The method includes designating files from the first computer for which back-up copies will be transferred to the second computer. The method includes transferring the files from the first computer to a portable computer readable medium. The method also includes delivering the portable computer readable medium to the destination user. The method further includes transferring the files from the delivered portable computer readable medium to the second computer for storage. In accordance with another aspect of the invention, a method is provided method for facilitating the transfer of back-up copies of one or more files from a first computer to a second computer. The method includes designating files from the first computer for which back-up copies will be transferred to the second computer. The method includes identifying a location of the second computer. The method includes transferring the files from first computer to a portable computer readable medium. The method includes selectively delivering the portable computer readable medium to a user of the destination computer based on a total size of the files being transferred. The portable computer readable medium is delivered to the destination user when the total size of the files is greater than or equal to a predetermined file size. The method includes selectively transferring the files from the first computer to the second computer via a communication network when the total size of the files is less than the predetermined file size. Alternatively, the invention may comprise various other methods and apparatuses. Other features will be in part apparent and in part pointed out hereinafter. | 20040331 | 20080408 | 20050127 | 62517.0 | 7 | LEE, WILSON | METHOD AND SYSTEM FOR SHARING STORAGE SPACE ON A COMPUTER | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,814,790 | ACCEPTED | Refrigerator and method for controlling the same | A refrigerator including a control unit for a condenser fan in connection with operation of a compressor if an outdoor temperature sensor is out of order. Since the condenser fan is driven in connection with the operation of the compressor, a trip phenomenon of the compressor generated due an overload of the compressor can be prevented, which results in stable operation of the refrigerator as well as increased reliability of the refrigerator. | 1. A refrigerator comprising: a compressor; a condenser; a condenser fan; an outdoor temperature sensor; and a control unit for determining whether the compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order and controlling the condenser fan in connection with operation of the compressor. 2. The refrigerator as set forth in claim 1, further comprising at least one built-in temperature sensor for detecting temperature of a freezing chamber and/or a refrigerating chamber, wherein the control unit calculates the operation load of the refrigerator based on the temperature of the freezing chamber and/or the refrigerating chamber detected by the at least one built-in temperature sensor. 3. The refrigerator as set forth in claim 1, wherein the outdoor temperature sensor includes a negative temperature characteristic thermistor and resistors. 4. A method for controlling a refrigerator, comprising: supplying a power; diagnosing disorder of an outdoor temperature sensor; determining whether a compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order; and controlling a condenser fan in connection with operation of the compressor. 5. The method as set forth in claim 1, wherein a voltage of the outdoor temperature sensor is compared to a reference voltage, and the disorder of the outdoor temperature sensor is diagnosed based on a result of the comparison. | CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of Korean Patent Application No. 2004-21496, filed on Mar. 30, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator and a method for controlling the same, and, more particularly, to a refrigerator and a method for controlling the same, which is capable of controlling a condenser fan in connection with operation of a compressor when an outdoor temperature sensor is out of order. 2. Description of the Related Art A refrigerator generates cold air required for refrigeration or freezing, by using a cooling system including a compressor, a condenser, an expansion unit, an evaporator, a condenser fan, various kinds of sensors for collecting information required to perform a cooling operation, etc. In the cooling system, the evaporator is disposed inside a body typically partitioned into a refrigerating chamber and a freezing chamber, and the compressor, the condenser, the condenser fan and the like are installed in a machine room under the body. The refrigerator employing such a cooling system performs self-diagnosis for components of the refrigerator before a normal cooling operation is performed. In the self-diagnosis, if an outdoor sensor is found to short or open, disorder of the outdoor sensor is alerted by a buzzer or a light emitting lamp. Simultaneously, operation of the condenser fan driven depending on the outdoor sensor is stopped since temperature obtained through the outdoor sensor is different from actual outdoor temperature. Then, when the compressor is driven according to operation load of the cooling system, it suffers from an overload as cooling function of the condenser is remarkably deteriorated due to the stoppage of the condenser fan. Particularly, when the temperature of the compressor rises excessively as the outdoor temperature becomes very high in the summer, an overload protector provided to protect the compressor operates to cut off a power supply, which results in a trip phenomenon wherein the operation of the compressor is compulsorily stopped. Since it takes a long time for this trip phenomenon of the compressor to disappear, reliability of the refrigerator is lowered and normal operation of the refrigerator for refrigerating or freezing food or beverages is hindered. SUMMARY OF THE INVENTION Therefore, it is an aspect of the invention to provide a refrigerator and a method for controlling the same, which is capable of preventing a trip phenomenon of a compressor by driving a condenser fan in connection with operation of the compressor if an outdoor temperature sensor is out of order. In accordance with one aspect of the present invention, there is provided a refrigerator comprising: a compressor; a condenser; a condenser fan; an outdoor temperature sensor; and a control unit for determining whether the compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order and controlling the condenser fan in connection with operation of the compressor. The refrigerator may further comprise at least one built-in temperature sensor for detecting temperature of a freezing chamber and/or a refrigerating chamber and the control unit calculates the operation load of the refrigerator based on the temperature of the freezing chamber and/or the refrigerating chamber detected by the at least one built-in temperature sensor. The outdoor temperature sensor may include a negative temperature characteristic thermistor and resistors. In accordance with another aspect of the present invention, there is provided a method for controlling a refrigerator, comprising: supplying a power; diagnosing disorder of an outdoor temperature sensor; determining whether a compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order; and controlling a condenser fan in connection with operation of the compressor. A voltage of the outdoor temperature sensor may be compared to a reference voltage, and the disorder of the outdoor temperature sensor is diagnosed based on a result of the comparison. BRIEF DESCRIPTION OF THE DRAWINGS The above aspects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings, in which: FIG. 1 is a block diagram showing a configuration of a refrigerator according to the present invention; FIG. 2 is an electrical circuit of an outdoor temperature sensor of FIG. 1; and FIG. 3 is a flow chart illustrating a method for controlling a refrigerator in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the annexed drawings. In a refrigerator in accordance with the present invention, a freezing chamber (not shown) and a refrigerating chamber (not shown) are provided with respective evaporators. A refrigerant cycle is configured by connecting each evaporator to a compressor, a condenser, an expansion valve, etc. by means of a refrigerant pipe. In addition, each evaporator is provided with a defrosting heater and a temperature sensor. As shown in FIG. 1, the refrigerator of the present invention includes various kinds of sensors required to perform cooling operation, that is, a freezing chamber sensor 10 for detecting the temperature of the freezing chamber, a refrigerating chamber sensor 12 for detecting the temperature of the freezing chamber, a freezing chamber evaporator temperature sensor 14 installed in the evaporator of the freezing chamber for detecting the temperature of the evaporator, a refrigerating chamber evaporator temperature sensor 16 installed in the evaporator of the refrigerating chamber for detecting the temperature of the evaporator, and an outdoor temperature sensor 18 for detecting outdoor temperature. These sensors provide information on the detected temperature to a control unit 1. A power supply 20 supplies power for each of components including the control unit 1 and the sensors. Upon receiving the power, the control unit 1 makes a self-diagnosis for disorder of the sensors to find the sensors open or short by comparing a voltage of each sensor to a preset voltage. After completing the self-diagnosis, the control unit 1 determines operation load of the refrigerator based on temperature information received from the sensors, drives a condenser fan 22, a compressor 24, a freezing chamber fan 26, and a refrigerating chamber fan 28 to perform cooling operation of the refrigerator, and drives a freezing chamber defrosting heater 30 and a refrigerating chamber defrosting heater 32 for performing defrosting operation of the refrigerator. A display unit 34 displays the operation state of the refrigerator and so on. The outdoor temperature sensor 18 includes resistors R1 and R2 for dividing an operating voltage Vcc, and a negative temperature characteristic (NTC) thermistor Th connected between a joining point between the resistors R1 and R2 and a ground. An outdoor detection signal corresponding to temperature detected by the thermistor Th is applied to the control unit 1 via the resistor R2. The control unit 1 converts the outdoor detection signal into a digital signal to recognize the outdoor temperature based on the converted temperature signal, i.e., a voltage value of the outdoor temperature sensor. The resistance of the thermistor Th depends on the outdoor temperature and, accordingly, the voltage of the outdoor temperature sensor is applied to the control unit 1. The control unit 1 makes a self-diagnosis for disorder of the outdoor temperature sensor by comparing the voltage value of the sensor to a preset voltage value. For example, the control unit 1 determines that the sensor is out of order due to short of the sensor, if the sensor voltage is less than the preset voltage value (e.g., 0.6 V), which results in detection of temperature higher than the actual outdoor temperature, and determines that the sensor is out of order due to open of the sensor, if the sensor voltage is more than the preset voltage value (e.g., 4.5 V), which results in detection of temperature lower than the actual outdoor temperature. When the disorder of the outdoor temperature sensor is diagnosed, the control unit 1 display the sensor disorder through the display unit 34 such that a user can read the sensor disorder. Although the sensor disorder takes place, since it does not indicate a critical defect by which it is difficult to make perform cooling operation of the refrigerating chamber and the freezing chamber, it is necessary to continue to drive the compressor in order to continue the cooling operation to refrigerate or freeze food or beverages until the disordered sensor is repaired or changed. In other words, if temperatures of the freezing chamber and the refrigerating chamber are higher than respective preset temperatures, the compressor is driven to supply cold air into the chambers in order to lower the temperatures of the chambers and is stopped when the temperatures of the chambers fall under the respective preset temperatures due to the cooling operation. The control unit 1 drives the condenser fan 22 in connection with the operation of the compressor when the outdoor temperature sensor is out of order, which will be described below with reference to FIG. 3. First, the refrigerator is powered on in operation 40. The control unit 1 is supplied with an operating voltage through the power supply 20 and checks a voltage value of the outdoor temperature sensor in operation 42. The control unit 1 compares the voltage value of the outdoor temperature sensor to a preset voltage value (for example, 0.6 V or 4.5 V) to determine whether the sensor is open or short in operation 44. As a result of the determination, if the sensor voltage is less than a preset lowest limit voltage (for example, 0.6 V) or more than a preset upper limit voltage (for example, 4.5 V), that is, if the sensor is open or short, the control unit 1 displays the disorder of the sensor on the display unit 34, compares temperatures detected by the freezing chamber temperature sensor 10 and the refrigerating chamber temperature sensor 12 to respective preset temperatures, and calculates the operation load of the refrigerator based a result of the comparison in operation 46. Next, the control unit 1 determines whether the compressor is driven or not based on the calculated operation load in operation 48. As a result of the determination in operation 48, if it is determined that the compressor is required to be driven as the temperatures of the chambers are higher than the respective preset temperatures and the operation load is large, the control unit 1 drives the condenser fan 22 at the same time as driving the compressor 24. Accordingly, although the outdoor temperature cannot be detected by the outdoor temperature sensor, the trip phenomenon of the compressor can be prevented since the condenser fan is driven as the compressor is driven in operation 50. As a result of the determination in operation 48, if it is determined that the compressor is not required to be driven as the operation load is not large, the control unit 1 stops the compressor 24 and the condenser fan 22 in operation 52. On the other hand, as a result of the determination in operation 44, if it is determined that the outdoor temperature sensor is not open or short, the control unit 1 controls the compressor and the condenser fan based on the outdoor temperature detected by the outdoor temperature sensor. As apparent from the above description, since the condenser fan is driven in connection with the operation of the compressor if the outdoor temperature sensor is out of order, the trip phenomenon of the compressor generated due an overload of the compressor can be prevented, which results in stable operation of the refrigerator as well as increase of reliability of the refrigerator. Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to a refrigerator and a method for controlling the same, and, more particularly, to a refrigerator and a method for controlling the same, which is capable of controlling a condenser fan in connection with operation of a compressor when an outdoor temperature sensor is out of order. 2. Description of the Related Art A refrigerator generates cold air required for refrigeration or freezing, by using a cooling system including a compressor, a condenser, an expansion unit, an evaporator, a condenser fan, various kinds of sensors for collecting information required to perform a cooling operation, etc. In the cooling system, the evaporator is disposed inside a body typically partitioned into a refrigerating chamber and a freezing chamber, and the compressor, the condenser, the condenser fan and the like are installed in a machine room under the body. The refrigerator employing such a cooling system performs self-diagnosis for components of the refrigerator before a normal cooling operation is performed. In the self-diagnosis, if an outdoor sensor is found to short or open, disorder of the outdoor sensor is alerted by a buzzer or a light emitting lamp. Simultaneously, operation of the condenser fan driven depending on the outdoor sensor is stopped since temperature obtained through the outdoor sensor is different from actual outdoor temperature. Then, when the compressor is driven according to operation load of the cooling system, it suffers from an overload as cooling function of the condenser is remarkably deteriorated due to the stoppage of the condenser fan. Particularly, when the temperature of the compressor rises excessively as the outdoor temperature becomes very high in the summer, an overload protector provided to protect the compressor operates to cut off a power supply, which results in a trip phenomenon wherein the operation of the compressor is compulsorily stopped. Since it takes a long time for this trip phenomenon of the compressor to disappear, reliability of the refrigerator is lowered and normal operation of the refrigerator for refrigerating or freezing food or beverages is hindered. | <SOH> SUMMARY OF THE INVENTION <EOH>Therefore, it is an aspect of the invention to provide a refrigerator and a method for controlling the same, which is capable of preventing a trip phenomenon of a compressor by driving a condenser fan in connection with operation of the compressor if an outdoor temperature sensor is out of order. In accordance with one aspect of the present invention, there is provided a refrigerator comprising: a compressor; a condenser; a condenser fan; an outdoor temperature sensor; and a control unit for determining whether the compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order and controlling the condenser fan in connection with operation of the compressor. The refrigerator may further comprise at least one built-in temperature sensor for detecting temperature of a freezing chamber and/or a refrigerating chamber and the control unit calculates the operation load of the refrigerator based on the temperature of the freezing chamber and/or the refrigerating chamber detected by the at least one built-in temperature sensor. The outdoor temperature sensor may include a negative temperature characteristic thermistor and resistors. In accordance with another aspect of the present invention, there is provided a method for controlling a refrigerator, comprising: supplying a power; diagnosing disorder of an outdoor temperature sensor; determining whether a compressor is operated or not based on operation load of the refrigerator if the outdoor temperature sensor is out of order; and controlling a condenser fan in connection with operation of the compressor. A voltage of the outdoor temperature sensor may be compared to a reference voltage, and the disorder of the outdoor temperature sensor is diagnosed based on a result of the comparison. | 20040401 | 20060411 | 20051006 | 98236.0 | 0 | NORMAN, MARC E | REFRIGERATOR AND METHOD FOR CONTROLLING THE SAME | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,938 | ACCEPTED | Poly(azine)-based charge transport materials | An improved organophotoreceptor comprises an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (a) a charge transport material having the formula where X1 and X2 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (b) a charge generating compound. Corresponding electrophotographic apparatuses, imaging methods, and methods of forming the charge transport material are described. | 1. An organophotoreceptor comprising an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (a) a charge transport material comprising a polymer having the formula: where X1 and X2 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (b) a charge generating compound. 2. An organophotoreceptor according to claim 1 wherein R1 and R2 comprise, each independently, an [(N,N-disubstituted)amino]aryl group. 3. An organophotoreceptor according to claim 1 wherein X1 and X2, each independently, comprise a —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 4. An organophotoreceptor according to claim 3 wherein X1 is a —Y4—CH2— group, and X2 is a —Y5—CH2CH(Y6H)CH2—Y1-Z1-Y2-Z2-Y3—CH2CH(Y7H)— group where Y1, Y2, Y3, Y4, Y5, Y6, and Y7 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1, and Z2, are, each independently, an aromatic group. 5. An organophotoreceptor according to claim 4 wherein Y1, Y2, and Y3 are, each independently, S; and Z1, and Z2, are, each independently, a phenylene group. 6. An organophotoreceptor according to claim 1 wherein the photoconductive element further comprises a second charge transport material. 7. An organophotoreceptor according to claim 6 wherein the second charge transport material comprises an electron transport compound. 8. An organophotoreceptor according to claim 1 wherein the photoconductive element further comprises a binder. 9. An electrophotographic imaging apparatus comprising: (a) a light imaging component; and (b) an organophotoreceptor oriented to receive light from the light imaging component, the organophotoreceptor comprising an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (i) a charge transport material comprising a polymer having the formula where X1 and X2 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (ii) a charge generating compound. 10. An electrophotographic imaging apparatus according to claim 9 wherein R1 and R2 comprise, each independently, an [(N,N-disubstituted)amino]aryl group. 11. An electrophotographic imaging apparatus according to claim 9 wherein X1 and X2, each independently, comprise a —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 12. An electrophotographic imaging apparatus according to claim 11 wherein X1 is a —Y4—CH2— group, and X2 is a —Y5—CH2CH(Y6H)CH2—Y1-Z1-Y2-Z2-Y3—CH2CH(Y7H)— group where Y1, Y2, Y3, Y4, Y5, Y6, and Y7 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1 and Z2, are, each independently, an aromatic group. 13. An electrophotographic imaging apparatus according to claim 9 wherein the photoconductive element further comprises a second charge transport material. 14. An electrophotographic imaging apparatus according to claim 13 wherein second charge transport material comprises an electron transport compound. 15. An electrophotographic imaging apparatus according to claim 9 further comprising a toner dispenser. 16. An electrophotographic imaging process comprising; (a) applying an electrical charge to a surface of an organophotoreceptor comprising an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising (i) a charge transport material comprising a polymer having the formula where X1 and X2 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (ii) a charge generating compound. (b) imagewise exposing the surface of the organophotoreceptor to radiation to dissipate charge in selected areas and thereby form a pattern of charged and uncharged areas on the surface; (c) contacting the surface with a toner to create a toned image; and (d) transferring the toned image to substrate. 17. An electrophotographic imaging process according to claim 16 wherein R1 and R2 comprise, each independently, an [(N,N-disubstituted)amino]aryl group. 18. An electrophotographic imaging process according to claim 16 wherein X1 and X2, each independently, comprise a —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 19. An electrophotographic imaging process according to claim 18 wherein X1 is a —Y4—CH2— group, and X2 is a —Y5—CH2CH(Y6H)CH2—Y1-Z1-Y2-Z2-Y3—CH2CH(Y7H)— group where Y1, Y2, Y3, Y4, Y5, Y6, and Y7 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1 and Z2, are, each independently, an aromatic group. 20. An electrophotographic imaging process according to claim 16 wherein the photoconductive element further comprises a second charge transport material. 21. An electrophotographic imaging process according to claim 20 wherein the second charge transport material comprises an electron transport compound. 22. An electrophotographic imaging process according to claim 16 wherein the photoconductive element further comprises a binder. 23. An electrophotographic imaging process according to claim 16 wherein the toner comprises colorant particles. 24. A charge transport material comprising a polymer having the formula where X1 and X2 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one. 25. A charge transport material according to claim 24 wherein R1 and R2 comprise, each independently, an [(N,N-disubstituted)amino]aryl group. 26. A charge transport material according to claim 24 wherein X1 and X2, each independently, comprise a —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 27. A charge transport material according to claim 26 wherein X1 is a —Y4—CH2— group, and X2 is a —Y5—CH2CH(Y6H)CH2—Y1-Z1-Y2-Z2-Y3—CH2CH(Y7H)— group where Y1, Y2, Y3, Y4, Y5, Y6, and Y7 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1, and Z2, are, each independently, an aromatic group. 28. A charge transport material according to claim 27 wherein Y1, Y2, and Y3 are, each independently, S; and Z1, and Z2, are, each independently, a phenylene group 29. A charge transport material according to claim 24 wherein Ar is an aromatic C6H3 group. 30. A method for forming a polymeric charge transport material, the method comprising the step of co-polymerizing a bridging compound having a bridging group and at least two functional groups with a charge transport material having the formula: where X3 and X4 are, each independently, a linking group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and E1 and E2 are, each independently, a reactive ring group. 31. A method for forming a polymeric charge transport material according to claim 30 wherein E1 and E2 are, each independently, an epoxy group, a thiiranyl group, an aziridino group, or an oxetanyl group. 32. A method for forming a polymeric charge transport material according to claim 30 wherein X3 and X4 are, each independently, a —(CH2)p— group, where p is an integer between 1 and 10, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRg group, a CRh group, a CRiRj group, or a SiRkR1 where Rg, Rh, Ri, Rj, Rk, and R1 are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 33. A method for forming a polymeric charge transport material according to claim 32 wherein X3 and X4, each independently, are O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group. 34. A method for forming a polymeric charge transport material according to claim 30 wherein the at least two functional groups, each independently, are selected from the group consisting of a hydroxyl group, a thiol group, amino groups, and a carboxyl group. 35. A method for forming a polymeric charge transport material according to claim 30 wherein the bridging group comprises a —(CH2)k— group, where k is an integer between 1 and 30, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRm group, a CRn group, a CRoRp group, or a SiRqRr where Rm, Rn, Ro, Rp, Rq, and Rr are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group. 36. A method for forming a polymeric charge transport material according to claim 30 wherein the bridging compound is selected from the group consisting of a diol, a dithiol, a diamine, a dicarboxlyic acid, a hydroxylamine, an amino acid, a hydroxyl acid, a thiol acid, a hydroxythiol, and a thioamine. 37. A method for forming a polymeric charge transport material according to claim 30 wherein R1 and R2 comprise, each independently, an [(N,N-disubstituted)amino]aryl group. | FIELD OF THE INVENTION This invention relates to organophotoreceptors suitable for use in electrophotography and, more specifically, to organophotoreceptors having a charge transport materials comprising a polymer having repeating aromatic azine groups. Furthermore, the invention further relates to methods for forming a charge transport material comprising a polymer having repeating aromatic azine groups. BACKGROUND OF THE INVENTION In electrophotography, an organophotoreceptor in the form of a plate, disk, sheet, belt, drum or the like having an electrically insulating photoconductive element on an electrically conductive substrate is imaged by first uniformly electrostatically charging the surface of the photoconductive layer, and then exposing the charged surface to a pattern of light. The light exposure selectively dissipates the charge in the illuminated areas where light strikes the surface, thereby forming a pattern of charged and uncharged areas, referred to as a latent image. A liquid or solid toner is then provided in the vicinity of the latent image, and toner droplets or particles deposit in the vicinity of either the charged or uncharged areas to create a toned image on the surface of the photoconductive layer. The resulting toned image can be transferred to a suitable ultimate or intermediate receiving surface, such as paper, or the photoconductive layer can operate as an ultimate receptor for the image. The imaging process can be repeated many times to complete a single image, for example, by overlaying images of distinct color components or effect shadow images, such as overlaying images of distinct colors to form a full color final image, and/or to reproduce additional images. Both single layer and multilayer photoconductive elements have been used. In single layer embodiments, a charge transport material and charge generating material are combined with a polymeric binder and then deposited on the electrically conductive substrate. In multilayer embodiments, the charge transport material and charge generating material are present in the element in separate layers, each of which can optionally be combined with a polymeric binder, deposited on the electrically conductive substrate. Two arrangements are possible for a two-layer photoconductive element. In one two-layer arrangement (the “dual layer” arrangement), the charge-generating layer is deposited on the electrically conductive substrate and the charge transport layer is deposited on top of the charge generating layer. In an alternate two-layer arrangement (the “inverted dual layer” arrangement), the order of the charge transport layer and charge generating layer is reversed. In both the single and multilayer photoconductive elements, the purpose of the charge generating material is to generate charge carriers (i.e., holes and/or electrons) upon exposure to light. The purpose of the charge transport material is to accept at least one type of these charge carriers and transport them through the charge transport layer in order to facilitate discharge of a surface charge on the photoconductive element. The charge transport material can be a charge transport compound, an electron transport compound, or a combination of both. When a charge transport compound is used, the charge transport compound accepts the hole carriers and transports them through the layer with the charge transport compound. When an electron transport compound is used, the electron transport compound accepts the electron carriers and transports them through the layer with the electron transport compound. Organophotoreceptors may be used for both dry and liquid electrophotography. There are many differences between dry and liquid electrophotography. A significant difference is that a dry toner is used in dry electrophotography, whereas a liquid toner is used in liquid electrophotography. A potential advantage of liquid electrophotography is that it can provide a higher resolution and thus sharper images than dry electrophotography because liquid toner particles can be generally significantly smaller than dry toner particles. As a result of their smaller size, liquid toners are able to provide images of higher optical density than dry toners. In liquid electrophotography, the organophotoreceptor is in contact with the liquid carrier of a liquid toner while the toner dries or pending transfer to a receiving surface. As a result, the charge transport material in the photoconductive element may be removed by extraction by the liquid carrier. Over a long period of operation, the amount of the charge transport material removed by extraction may be significant and, therefore, detrimental to the performance of the organophotoreceptor. SUMMARY OF THE INVENTION This invention provides organophotoreceptors having good electrostatic properties such as high Vacc and low Vdis. This invention also provides organophotoreceptors comprising a charge transport material having reduced extraction by liquid carriers. In a first aspect, an organophotoreceptor comprises an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (a) a charge transport material comprising a polymer having the formula: where X1 and X2 are, each independently, a linking group, such as —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group, such as an aromatic C6H3 group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (b) a charge generating compound. The asterisks (*) indicate terminal groups of the polymer of Formula (I), which may vary between different polymer units depending on the state of the particular polymerization process at the end of the polymerization step. The organophotoreceptor may be provided, for example, in the form of a plate, a flexible belt, a flexible disk, a sheet, a rigid drum, or a sheet around a rigid or compliant drum. In one embodiment, the organophotoreceptor includes: (a) a photoconductive element comprising the charge transport material, the charge generating compound, a second charge transport material, and a polymeric binder; and (b) the electrically conductive substrate. In a second aspect, the invention features an electrophotographic imaging apparatus that comprises (a) a light imaging component; and (b) the above-described organophotoreceptor oriented to receive light from the light imaging component. The apparatus can further comprise a toner dispenser, such as a liquid toner dispenser. The method of electrophotographic imaging with photoreceptors containing the above noted charge transport materials is also described. In a third aspect, the invention features an electrophotographic imaging process that includes (a) applying an electrical charge to a surface of the above-described organophotoreceptor; (b) imagewise exposing the surface of the organophotoreceptor to radiation to dissipate charge in selected areas and thereby form a pattern of at least relatively charged and uncharged areas on the surface; (c) contacting the surface with a toner, such as a liquid toner that includes a dispersion of colorant particles in an organic liquid, to create a toned image; and (d) transferring the toned image to a substrate. In a fourth aspect, the invention features a charge transport material comprising a polymer having Formula (I) above. In a fifth aspect, the invention features a method for forming a polymeric charge transport material, the method comprising the step of co-polymerizing a bridging compound having a bridging group and at least two functional groups with a charge transport material having the formula: where X3 and X4 are, each independently, a linking group, such as a —(CH2)p— group, where p is an integer between 1 and 10, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRg group, a CRh group, a CRiRj group, or a SiRkR1 where Rg, Rh, Ri, Rj, Rk, and Rl are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group, such as an aromatic C6H3 group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and E1 and E2 are, each independently, a reactive ring group, such as an epoxy group, a thiiranyl group, an aziridino group, and an oxetanyl group. In some embodiments, the bridging group is a —(CH2)k— group, where k is an integer between 1 and 30, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRm group, a CRn group, a CRoRp group, or a SiRqRr where Rm, Rn, Ro, Rp, Rq, and Rr are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group. In other embodiments, the functional groups, each independently, are a hydroxyl group, a thiol group, a carboxyl group, and an amino group. The invention provides suitable charge transport materials for organophotoreceptors featuring a combination of good chemical and electrostatic properties. These photoreceptors can be used successfully with toners, including liquid toners, to produce high quality images. The high quality of the imaging system can be maintained after repeated cycling. Other features and advantages of the invention will be apparent from the following description of the particular embodiments thereof, and from the claims. DETAILED DESCRIPTION OF THE INVENTION An organophotoreceptor as described herein has an electrically conductive substrate and a photoconductive element including a charge generating compound and a charge transport material comprising a polymer having repeating aromatic azine groups. These charge transport materials have desirable properties as evidenced by their performance in organophotoreceptors for electrophotography. In particular, the charge transport materials of this invention have high charge carrier mobilities and good compatibility with various binder materials, and possess excellent electrophotographic properties. The organophotoreceptors according to this invention generally have a high photosensitivity, a low residual potential, and a high stability with respect to cycle testing, crystallization, and organophotoreceptor bending and stretching. The organophotoreceptors are particularly useful in laser printers and the like as well as fax machines, photocopiers, scanners and other electronic devices based on electrophotography. The use of these charge transport materials is described in more detail below in the context of laser printer use, although their application in other devices operating by electrophotography can be generalized from the discussion below. To produce high quality images, particularly after multiple cycles, it is desirable for the charge transport materials to form a homogeneous mixture with the polymeric binder and remain approximately homogeneously distributed through the organophotoreceptor material during the cycling of the material. In addition, it is desirable to increase the amount of charge that the charge transport material can accept (indicated by a parameter known as the acceptance voltage or “Vacc”), and to reduce retention of that charge upon discharge (indicated by a parameter known as the discharge voltage or “Vdis”). Charge transport materials may comprise monomeric molecules (e.g., N-ethyl-carbazolo-3-aldehyde-N-methyl-N-phenyl-hydrazone, dimeric molecules (e.g., disclosed in U.S. Pat. Nos. 6,140,004 and 6,670,085), or polymeric compositions (e.g., poly(vinylcarbazole)). Furthermore, the charge transport materials can be classified as a charge transport compound or an electron transport compound. There are many charge transport compounds and electron transport compounds known in the art for electrophotography. Non-limiting examples of charge transport compounds include, for example, pyrazoline derivatives, fluorene derivatives, oxadiazole derivatives, stilbene derivatives, enamine derivatives, enamine stilbene derivatives, hydrazone derivatives, carbazole hydrazone derivatives, (N,N-disubstituted)arylamines such as triaryl amines, polyvinyl carbazole, polyvinyl pyrene, polyacenaphthylene, and the charge transport compounds described in U.S. Pat. Nos. 6,689,523, 6,670,085, and 6,696,209, and U.S. patent application Ser. Nos. 10/431,135, 10/431,138, 10/699,364, 10/663,278, 10/699,581, 10/449,554, 10/748,496, 10/789,094, 10/644,547, 10/749,174, 10/749,171, 10/749,418, 10/699,039, 10/695,581, 10/692,389, 10/634,164, 10/663,970, 10/749,164, 10/772,068, 10/749,178, 10/758,869, 10/695,044, 10/772,069, 10/789,184, 10/789,077, 10/775,429, 10/775,429, 10/670,483, 10/671,255, 10/663,971, 10/760,039. All the above patents and patent applications are incorporated herein by reference. Non-limiting examples of electron transport compounds include, for example, bromoaniline, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-indeno[1,2-b]thiophene-4-one, and 1,3,7-trinitrodibenzo thiophene-5,5-dioxide, (2,3-diphenyl-1-indenylidene)malononitrile, 4H-thiopyran-1,1-dioxide and its derivatives such as 4-dicyanomethylene-2,6-diphenyl-4H-thiopyran-1,1-dioxide, 4-dicyanomethylene-2,6-di-m-tolyl-4H-thiopyran-1,1-dioxide, and unsymmetrically substituted 2,6-diaryl-4H-thiopyran-1,1-dioxide such as 4H-1,1-dioxo-2-(p-isopropylphenyl)-6-phenyl-4-(dicyanomethylidene)thiopyran and 4H-1,1-dioxo-2-(p-isopropylphenyl)-6-(2-thienyl)-4-(dicyanomethylidene)thiopyran, derivatives of phospha-2,5-cyclohexadiene, alkoxycarbonyl-9-fluorenylidene)malononitrile derivatives such as (4-n-butoxycarbonyl-9-fluorenylidene)malononitrile, (4-phenethoxycarbonyl-9-fluorenylidene)malononitrile, (4-carbitoxy-9-fluorenylidene)malononitrile, and diethyl(4-n-butoxycarbonyl-2,7-dinitro-9-fluorenylidene)malonate, anthraquinodimethane derivatives such as 11,11,12,12-tetracyano-2-alkylanthraquinodimethane and 11,11-dicyano-12,12-bis(ethoxycarbonyl)anthraquinodimethane, anthrone derivatives such as 1-chloro-10-[bis(ethoxycarbonyl)methylene]anthrone, 1,8-dichloro-10-[bis(ethoxycarbonyl) methylene]anthrone, 1,8-dihydroxy-10-[bis(ethoxycarbonyl)methylene] anthrone, and 1-cyano-10-[bis(ethoxycarbonyl)methylene)anthrone, 7-nitro-2-aza-9-fluroenylidene-malononitrile, diphenoquinone derivatives, benzoquinone derivatives, naphtoquinone derivatives, quinine derivatives, tetracyanoethylenecyanoethylene, 2,4,8-trinitro thioxantone, dinitrobenzene derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, nitroanthraquinone derivatives, dinitroanthraquinone derivatives, succinic anhydride, maleic anhydride, dibromo maleic anhydride, pyrene derivatives, carbazole derivatives, hydrazone derivatives, N,N-dialkylaniline derivatives, diphenylamine derivatives, triphenylamine derivatives, triphenylmethane derivatives, tetracyano quinodimethane, 2,4,5,7-tetranitro-9-fluorenone, 2,4,7-trinitro-9-dicyanomethylene fluorenone, 2,4,5,7-tetranitroxanthone derivatives, 2,4,8-trinitrothioxanthone derivatives, 1,4,5,8-naphthalene bis-dicarboximide derivatives as described in U.S. Pat. Nos. 5,232,800, 4,468,444, and 4,442,193 and phenylazoquinolide derivatives as described in U.S. Pat. No. 6,472,514. In some embodiments of interest, the electron transport compound comprises an (alkoxycarbonyl-9-fluorenylidene)malononitrile derivative, such as (4-n-butoxycarbonyl-9-fluorenylidene)malononitrile, and 1,4,5,8-naphthalene bis-dicarboximide derivatives. Although there are many charge transport materials available, there is a need for other charge transport materials to meet the various requirements of particular electrophotography applications. In electrophotography applications, a charge-generating compound within an organophotoreceptor absorbs light to form electron-hole pairs. These electrons and holes can be transported over an appropriate time frame under a large electric field to discharge locally a surface charge that is generating the field. The discharge of the field at a particular location results in a surface charge pattern that essentially matches the pattern drawn with the light. This charge pattern then can be used to guide toner deposition. The charge transport materials described herein are especially effective at transporting charge, and in particular holes from the electron-hole pairs formed by the charge generating compound. In some embodiments, a specific electron transport compound or charge transport compound can also be used along with the charge transport material of this invention. The layer or layers of materials containing the charge generating compound and the charge transport materials are within an organophotoreceptor. To print a two dimensional image using the organophotoreceptor, the organophotoreceptor has a two dimensional surface for forming at least a portion of the image. The imaging process then continues by cycling the organophotoreceptor to complete the formation of the entire image and/or for the processing of subsequent images. The organophotoreceptor may be provided in the form of a plate, a flexible belt, a disk, a rigid drum, a sheet around a rigid or compliant drum, or the like. The charge transport material can be in the same layer as the charge generating compound and/or in a different layer from the charge generating compound. Additional layers can be used also, as described further below. In some embodiments, the organophotoreceptor material comprises, for example: (a) a charge transport layer comprising the charge transport material and a polymeric binder; (b) a charge generating layer comprising the charge generating compound and a polymeric binder; and (c) the electrically conductive substrate. The charge transport layer may be intermediate between the charge generating layer and the electrically conductive substrate. Alternatively, the charge generating layer may be intermediate between the charge transport layer and the electrically conductive substrate. In further embodiments, the organophotoreceptor material has a single layer with both a charge transport material and a charge generating compound within a polymeric binder. The organophotoreceptors can be incorporated into an electrophotographic imaging apparatus, such as laser printers. In these devices, an image is formed from physical embodiments and converted to a light image that is scanned onto the organophotoreceptor to form a surface latent image. The surface latent image can be used to attract toner onto the surface of the organophotoreceptor, in which the toner image is the same or the negative of the light image projected onto the organophotoreceptor. The toner can be a liquid toner or a dry toner. The toner is subsequently transferred, from the surface of the organophotoreceptor, to a receiving surface, such as a sheet of paper. After the transfer of the toner, the surface is discharged, and the material is ready to cycle again. The imaging apparatus can further comprise, for example, a plurality of support rollers for transporting a paper receiving medium and/or for movement of the photoreceptor, a light imaging component with suitable optics to form the light image, a light source, such as a laser, a toner source and delivery system and an appropriate control system. An electrophotographic imaging process generally can comprise (a) applying an electrical charge to a surface of the above-described organophotoreceptor; (b) imagewise exposing the surface of the organophotoreceptor to radiation to dissipate charge in selected areas and thereby form a pattern of charged and uncharged areas on the surface; (c) exposing the surface with a toner, such as a liquid toner that includes a dispersion of colorant particles in an organic liquid to create a toner image, to attract toner to the charged or discharged regions of the organophotoreceptor; and (d) transferring the toner image to a substrate. As described herein, an organophotoreceptor comprises a charge transport material having the formula: where X1 and X2 are, each independently, a linking group, such as —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, R, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one. A heterocyclic group includes any monocyclic or polycyclic (e.g., bicyclic, tricyclic, etc.) ring compound having at least a heteroatom (e.g., O, S, N, P, B, Si, etc.) in the ring. An aromatic group can be any conjugated ring system containing 4n+2 pi-electrons. There are many criteria available for determining aromaticity. A widely employed criterion for the quantitative assessment of aromaticity is the resonance energy. Specifically, an aromatic group has a resonance energy. In some embodiments, the resonance energy of the aromatic group is at least 10 KJ/mol. In further embodiments, the resonance energy of the aromatic group is greater than 0.1 KJ/mol. Aromatic groups may be classified as an aromatic heterocyclic group which contains at least a heteroatom in the 4n+2 pi-electron ring, or as an aryl group which does not contain a heteroatom in the 4n+2 pi-electron ring. The aromatic group may comprise a combination of aromatic heterocyclic group and aryl group. Nonetheless, either the aromatic heterocyclic or the aryl group may have at least one heteroatom in a substituent attached to the 4n+2 pi-electron ring. Furthermore, either the aromatic heterocyclic or the aryl group may comprise a monocyclic or polycyclic (such as bicyclic, tricyclic, etc.) ring. Non-limiting examples of the aromatic heterocyclic group are furanyl, thiophenyl, pyrrolyl, indolyl, carbazolyl, benzofuranyl, benzothiophenyl, dibenzofuranyl, dibenzothiophenyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, tetrazinyl, petazinyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, acridinyl, phenanthridinyl, phenanthrolinyl, anthyridinyl, purinyl, pteridinyl, alloxazinyl, phenazinyl, phenothiazinyl, phenoxazinyl, phenoxathiinyl, dibenzo(1,4)dioxinyl, thianthrenyl, and a combination thereof. The aromatic heterocyclic group may also include any combination of the above aromatic heterocyclic groups bonded together either by a bond (as in bicarbazolyl) or by a linking group (as in 1,6 di(10H-10-phenothiazinyl)hexane). The linking group may include an aliphatic group, an aromatic group, a heterocyclic group, or a combination thereof. Furthermore, either an aliphatic group or an aromatic group within a linking group may comprise at least one heteroatom such as O, S, Si, and N. Non-limiting examples of the aryl group are phenyl, naphthyl, benzyl, or tolanyl group, sexiphenylene, phenanthrenyl, anthracenyl, coronenyl, and tolanylphenyl. The aryl group may also include any combination of the above aryl groups bonded together either by a bond (as in biphenyl group) or a linking group (as in stilbenyl, diphenyl sulfone, an arylamine group). The linking group may include an aliphatic group, an aromatic group, a heterocyclic group, or a combination thereof. Furthermore, either an aliphatic group or an aromatic group within a linking group may comprise at least one heteroatom such as O, S, Si, and N. Substitution is liberally allowed on the chemical groups to affect various physical effects on the properties of the compounds, such as mobility, sensitivity, solubility, stability, and the like, as is known generally in the art. In the description of chemical substituents, there are certain practices common to the art that are reflected in the use of language. The term group indicates that the generically recited chemical entity (e.g., alkyl group, phenyl group, aromatic group, etc.) may have any substituent thereon which is consistent with the bond structure of that group. For example, where the term ‘alkyl group’ is used, that term would not only include unsubstituted linear, branched and cyclic alkyls, such as methyl, ethyl, isopropyl, tert-butyl, cyclohexyl, dodecyl and the like, but also substituents having heteroatom, such as 3-ethoxylpropyl, 4-(N,N-diethylamino)butyl, 3-hydroxypentyl, 2-thiolhexyl, 1,2,3-tribromoopropyl, and the like, and aromatic group, such as phenyl, naphthyl, carbazolyl, pyrrole, and the like. However, as is consistent with such nomenclature, no substitution would be included within the term that would alter the fundamental bond structure of the underlying group. For example, where a phenyl group is recited, substitution such as 2- or 4-aminophenyl, 2- or 4-(N,N-disubstituted)aminophenyl, 2,4-dihydroxyphenyl, 2,4,6-trithiophenyl, 2,4,6-trimethoxyphenyl and the like would be acceptable within the terminology, while substitution of 1,1,2,2,3,3-hexamethylphenyl would not be acceptable as that substitution would require the ring bond structure of the phenyl group to be altered to a non-aromatic form. Where the term moiety is used, such as alkyl moiety or phenyl moiety, that terminology indicates that the chemical material is not substituted. Where the term alkyl moiety is used, that term represents only an unsubstituted alkyl hydrocarbon group, whether branched, straight chain, or cyclic. Organophotoreceptors The organophotoreceptor may be, for example, in the form of a plate, a sheet, a flexible belt, a disk, a rigid drum, or a sheet around a rigid or compliant drum, with flexible belts and rigid drums generally being used in commercial embodiments. The organophotoreceptor may comprise, for example, an electrically conductive substrate and on the electrically conductive substrate a photoconductive element in the form of one or more layers. The photoconductive element can comprise both a charge transport material and a charge generating compound in a polymeric binder, which may or may not be in the same layer, as well as a second charge transport material such as a charge transport compound or an electron transport compound in some embodiments. For example, the charge transport material and the charge generating compound can be in a single layer. In other embodiments, however, the photoconductive element comprises a bilayer construction featuring a charge generating layer and a separate charge transport layer. The charge generating layer may be located intermediate between the electrically conductive substrate and the charge transport layer. Alternatively, the photoconductive element may have a structure in which the charge transport layer is intermediate between the electrically conductive substrate and the charge generating layer. The electrically conductive substrate may be flexible, for example in the form of a flexible web or a belt, or inflexible, for example in the form of a drum. A drum can have a hollow cylindrical structure that provides for attachment of the drum to a drive that rotates the drum during the imaging process. Typically, a flexible electrically conductive substrate comprises an electrically insulating substrate and a thin layer of electrically conductive material onto which the photoconductive material is applied. The electrically insulating substrate may be paper or a film forming polymer such as polyester (e.g., polyethylene terephthalate or polyethylene naphthalate), polyimide, polysulfone, polypropylene, nylon, polyester, polycarbonate, polyvinyl resin, polyvinyl fluoride, polystyrene and the like. Specific examples of polymers for supporting substrates included, for example, polyethersulfone (STABAR™ S-100, available from ICI), polyvinyl fluoride (Tedlar®, available from E.I. DuPont de Nemours & Company), polybisphenol-A polycarbonate (MAKROFOL™, available from Mobay Chemical Company) and amorphous polyethylene terephthalate (MELINAR™, available from ICI Americas, Inc.). The electrically conductive materials may be graphite, dispersed carbon black, iodine, conductive polymers such as polypyrroles and Calgon® conductive polymer 261 (commercially available from Calgon Corporation, Inc., Pittsburgh, Pa.), metals such as aluminum, titanium, chromium, brass, gold, copper, palladium, nickel, or stainless steel, or metal oxide such as tin oxide or indium oxide. In embodiments of particular interest, the electrically conductive material is aluminum. Generally, the photoconductor substrate has a thickness adequate to provide the required mechanical stability. For example, flexible web substrates generally have a thickness from about 0.01 to about 1 mm, while drum substrates generally have a thickness from about 0.5 mm to about 2 mm. The charge generating compound is a material that is capable of absorbing light to generate charge carriers (such as a dye or pigment). Non-limiting examples of suitable charge generating compounds include, for example, metal-free phthalocyanines (e.g., ELA 8034 metal-free phthalocyanine available from H.W. Sands, Inc. or Sanyo Color Works, Ltd., CGM-X01), metal phthalocyanines such as titanium phthalocyanine, copper phthalocyanine, oxytitanium phthalocyanine (also referred to as titanyl oxyphthalocyanine, and including any crystalline phase or mixtures of crystalline phases that can act as a charge generating compound), hydroxygallium phthalocyanine, squarylium dyes and pigments, hydroxy-substituted squarylium pigments, perylimides, polynuclear quinones available from Allied Chemical Corporation under the trade name INDOFAST™ Double Scarlet, INDOFAST™ Violet Lake B, INDOFAST™ Brilliant Scarlet and INDOFAST™ Orange, quinacridones available from DuPont under the trade name MONASTRAL™ Red, MONASTRAL™ Violet and MONASTRAL™ Red Y, naphthalene 1,4,5,8-tetracarboxylic acid derived pigments including the perinones, tetrabenzoporphyrins and tetranaphthaloporphyrins, indigo- and thioindigo dyes, benzothioxanthene-derivatives, perylene 3,4,9,10-tetracarboxylic acid derived pigments, polyazo-pigments including bisazo-, trisazo- and tetrakisazo-pigments, polymethine dyes, dyes containing quinazoline groups, tertiary amines, amorphous selenium, selenium alloys such as selenium-tellurium, selenium-tellurium-arsenic and selenium-arsenic, cadmium sulphoselenide, cadmium selenide, cadmium sulphide, and mixtures thereof. For some embodiments, the charge generating compound comprises oxytitanium phthalocyanine (e.g., any phase thereof), hydroxygallium phthalocyanine or a combination thereof. The photoconductive layer of this invention may optionally contain a second charge transport material which may be a charge transport compound, an electron transport compound, or a combination of both. Generally, any charge transport compound or electron transport compound known in the art can be used as the second charge transport material. An electron transport compound and a UV light stabilizer can have a synergistic relationship for providing desired electron flow within the photoconductor. The presence of the UV light stabilizers alters the electron transport properties of the electron transport compounds to improve the electron transporting properties of the composite. UV light stabilizers can be ultraviolet light absorbers or ultraviolet light inhibitors that trap free radicals. UV light absorbers can absorb ultraviolet radiation and dissipate it as heat. UV light inhibitors are thought to trap free radicals generated by the ultraviolet light and after trapping of the free radicals, subsequently to regenerate active stabilizer moieties with energy dissipation. In view of the synergistic relationship of the UV stabilizers with electron transport compounds, the particular advantages of the UV stabilizers may not be their UV stabilizing abilities, although the UV stabilizing ability may be further advantageous in reducing degradation of the organophotoreceptor over time. The improved synergistic performance of organophotoreceptors with layers comprising both an electron transport compound and a UV stabilizer are described further in copending U.S. patent application Ser. No. 10/425,333 filed on Apr. 28, 2003 to Zhu, entitled “Organophotoreceptor With A Light Stabilizer,” incorporated herein by reference. Non-limiting examples of suitable light stabilizer include, for example, hindered trialkylamines such as Tinuvin 144 and Tinuvin 292 (from Ciba Specialty Chemicals, Terrytown, N.Y.), hindered alkoxydialkylamines such as Tinuvin 123 (from Ciba Specialty Chemicals), benzotriazoles such as Tinuvan 328, Tinuvin 900 and Tinuvin 928 (from Ciba Specialty Chemicals), benzophenones such as Sanduvor 3041 (from Clariant Corp., Charlotte, N.C.), nickel compounds such as Arbestab (from Robinson Brothers Ltd, West Midlands, Great Britain), salicylates, cyanocinnamates, benzylidene malonates, benzoates, oxanilides such as Sanduvor VSU (from Clariant Corp., Charlotte, N.C.), triazines such as Cyagard UV-1164 (from Cytec Industries Inc., N.J.), polymeric sterically hindered amines such as Luchem (from Atochem North America, Buffalo, N.Y.). In some embodiments, the light stabilizer is selected from the group consisting of hindered trialkylamines having the following formula: where R1, R2, R3, R4, R6, R7, R8, R10, R11, R12, R13, R14, R15 are, each independently, hydrogen, alkyl group, or ester, or ether group; and R5, R9, and R14 are, each independently, alkyl group; and X is a linking group selected from the group consisting of —O—CO—(CH2)m—CO—O— where m is between 2 to 20. The binder generally is capable of dispersing or dissolving the charge transport material (in the case of the charge transport layer or a single layer construction), the charge generating compound (in the case of the charge generating layer or a single layer construction) and/or an electron transport compound for appropriate embodiments. Examples of suitable binders for both the charge generating layer and charge transport layer generally include, for example, polystyrene-co-butadiene, polystyrene-co-acrylonitrile, modified acrylic polymers, polyvinyl acetate, styrene-alkyd resins, soya-alkyl resins, polyvinylchloride, polyvinylidene chloride, polyacrylonitrile, polycarbonates, polyacrylic acid, polyacrylates, polymethacrylates, styrene polymers, polyvinyl butyral, alkyd resins, polyamides, polyurethanes, polyesters, polysulfones, polyethers, polyketones, phenoxy resins, epoxy resins, silicone resins, polysiloxanes, poly(hydroxyether) resins, polyhydroxystyrene resins, novolak, poly(phenylglycidyl ether)-co-dicyclopentadiene, copolymers of monomers used in the above-mentioned polymers, and combinations thereof. Specific suitable binders include, for example, polyvinyl butyral, polycarbonate, and polyester. Non-limiting examples of polyvinyl butyral include BX-1 and BX-5 from Sekisui Chemical Co. Ltd., Japan. Non-limiting examples of suitable polycarbonate include polycarbonate A which is derived from bisphenol-A (e.g. Iupilon-A from Mitsubishi Engineering Plastics, or Lexan 145 from General Electric); polycarbonate Z which is derived from cyclohexylidene bisphenol (e.g. Iupilon-Z from Mitsubishi Engineering Plastics Corp, White Plain, N.Y.); and polycarbonate C which is derived from methylbisphenol A (from Mitsubishi Chemical Corporation). Non-limiting examples of suitable polyester binders include ortho-polyethylene terephthalate (e.g. OPET TR-4 from Kanebo Ltd., Yamaguchi, Japan). Suitable optional additives for any one or more of the layers include, for example, antioxidants, coupling agents, dispersing agents, curing agents, surfactants, and combinations thereof. The photoconductive element overall typically has a thickness from about 10 microns to about 45 microns. In the dual layer embodiments having a separate charge generating layer and a separate charge transport layer, charge generation layer generally has a thickness form about 0.5 microns to about 2 microns, and the charge transport layer has a thickness from about 5 microns to about 35 microns. In embodiments in which the charge transport material and the charge generating compound are in the same layer, the layer with the charge generating compound and the charge transport composition generally has a thickness from about 7 microns to about 30 microns. In embodiments with a distinct electron transport layer, the electron transport layer has an average thickness from about 0.5 microns to about 10 microns and in further embodiments from about 1 micron to about 3 microns. In general, an electron transport overcoat layer can increase mechanical abrasion resistance, increases resistance to carrier liquid and atmospheric moisture, and decreases degradation of the photoreceptor by corona gases. A person of ordinary skill in the art will recognize that additional ranges of thickness within the explicit ranges above are contemplated and are within the present disclosure. Generally, for the organophotoreceptors described herein, the charge generation compound is in an amount from about 0.5 to about 25 weight percent, in further embodiments in an amount from about 1 to about 15 weight percent, and in other embodiments in an amount from about 2 to about 10 weight percent, based on the weight of the photoconductive layer. The charge transport material is in an amount from about 10 to about 80 weight percent, based on the weight of the photoconductive layer, in further embodiments in an amount from about 35 to about 60 weight percent, and in other embodiments from about 45 to about 55 weight percent, based on the weight of the photoconductive layer. The optional second charge transport material, when present, can be in an amount of at least about 2 weight percent, in other embodiments from about 2.5 to about 25 weight percent, based on the weight of the photoconductive layer, and in further embodiments in an amount from about 4 to about 20 weight percent, based on the weight of the photoconductive layer. The binder is in an amount from about 15 to about 80 weight percent, based on the weight of the photoconductive layer, and in further embodiments in an amount from about 20 to about 75 weight percent, based on the weight of the photoconductive layer. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges of compositions are contemplated and are within the present disclosure. For the dual layer embodiments with a separate charge generating layer and a charge transport layer, the charge generation layer generally comprises a binder in an amount from about 10 to about 90 weight percent, in further embodiments from about 15 to about 80 weight percent and in some embodiments in an amount from about 20 to about 75 weight percent, based on the weight of the charge generation layer. The optional charge transport material in the charge generating layer, if present, generally can be in an amount of at least about 2.5 weight percent, in further embodiments from about 4 to about 30 weight percent and in other embodiments in an amount from about 10 to about 25 weight percent, based on the weight of the charge generating layer. The charge transport layer generally comprises a binder in an amount from about 20 weight percent to about 70 weight percent and in further embodiments in an amount from about 30 weight percent to about 50 weight percent. A person of ordinary skill in the art will recognize that additional ranges of binder concentrations for the dual layer embodiments within the explicit ranges above are contemplated and are within the present disclosure. For the embodiments with a single layer having a charge generating compound and a charge transport material, the photoconductive layer generally comprises a binder, a charge transport material, and a charge generation compound. The charge generation compound can be in an amount from about 0.05 to about 25 weight percent and in further embodiment in an amount from about 2 to about 15 weight percent, based on the weight of the photoconductive layer. The charge transport material can be in an amount from about 10 to about 80 weight percent, in other embodiments from about 25 to about 65 weight percent, in additional embodiments from about 30 to about 60 weight percent and in further embodiments in an amount from about 35 to about 55 weight percent, based on the weight of the photoconductive layer, with the remainder of the photoconductive layer comprising the binder, and optionally additives, such as any conventional additives. A single layer with a charge transport composition and a charge generating compound generally comprises a binder in an amount from about 10 weight percent to about 75 weight percent, in other embodiments from about 20 weight percent to about 60 weight percent, and in further embodiments from about 25 weight percent to about 50 weight percent. Optionally, the layer with the charge generating compound and the charge transport material may comprise a second charge transport material. The optional second charge transport material, if present, generally can be in an amount of at least about 2.5 weight percent, in further embodiments from about 4 to about 30 weight percent and in other embodiments in an amount from about 10 to about 25 weight percent, based on the weight of the photoconductive layer. A person of ordinary skill in the art will recognize that additional composition ranges within the explicit compositions ranges for the layers above are contemplated and are within the present disclosure. In general, any layer with an electron transport layer can advantageously further include a UV light stabilizer. In particular, the electron transport layer generally can comprise an electron transport compound, a binder, and an optional UV light stabilizer. An overcoat layer comprising an electron transport compound is described further in copending U.S. patent application Ser. No. 10/396,536 to Zhu et al. entitled, “Organophotoreceptor With An Electron Transport Layer,” incorporated herein by reference. For example, an electron transport compound as described above may be used in the release layer of the photoconductors described herein. The electron transport compound in an electron transport layer can be in an amount from about 10 to about 50 weight percent, and in other embodiments in an amount from about 20 to about 40 weight percent, based on the weight of the electron transport layer. A person of ordinary skill in the art will recognize that additional ranges of compositions within the explicit ranges are contemplated and are within the present disclosure. The UV light stabilizer, if present, in any one or more appropriate layers of the photoconductor generally is in an amount from about 0.5 to about 25 weight percent and in some embodiments in an amount from about 1 to about 10 weight percent, based on the weight of the particular layer. A person of ordinary skill in the art will recognize that additional ranges of compositions within the explicit ranges are contemplated and are within the present disclosure. For example, the photoconductive layer may be formed by dispersing or dissolving the components, such as one or more of a charge generating compound, the charge transport material of this invention, a second charge transport material such as a charge transport compound or an electron transport compound, a UV light stabilizer, and a polymeric binder in organic solvent, coating the dispersion and/or solution on the respective underlying layer and drying the coating. In particular, the components can be dispersed by high shear homogenization, ball-milling, attritor milling, high energy bead (sand) milling or other size reduction processes or mixing means known in the art for effecting particle size reduction in forming a dispersion. The photoreceptor may optionally have one or more additional layers as well. An additional layer can be, for example, a sub-layer or an overcoat layer, such as a barrier layer, a release layer, a protective layer, or an adhesive layer. A release layer or a protective layer may form the uppermost layer of the photoconductor element. A barrier layer may be sandwiched between the release layer and the photoconductive element or used to overcoat the photoconductive element. The barrier layer provides protection from abrasion to the underlayers. An adhesive layer locates and improves the adhesion between a photoconductive element, a barrier layer and a release layer, or any combination thereof. A sub-layer is a charge blocking layer and locates between the electrically conductive substrate and the photoconductive element. The sub-layer may also improve the adhesion between the electrically conductive substrate and the photoconductive element. Suitable barrier layers include, for example, coatings such as crosslinkable siloxanol-colloidal silica coating and hydroxylated silsesquioxane-colloidal silica coating, and organic binders such as polyvinyl alcohol, methyl vinyl ether/maleic anhydride copolymer, casein, polyvinyl pyrrolidone, polyacrylic acid, gelatin, starch, polyurethanes, polyimides, polyesters, polyamides, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polycarbonates, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl formal, polyacrylonitrile, polymethyl methacrylate, polyacrylates, polyvinyl carbazoles, copolymers of monomers used in the above-mentioned polymers, vinyl chloride/vinyl acetate/vinyl alcohol terpolymers, vinyl chloride/vinyl acetate/maleic acid terpolymers, ethylene/vinyl acetate copolymers, vinyl chloride/vinylidene chloride copolymers, cellulose polymers, and mixtures thereof. The above barrier layer polymers optionally may contain small inorganic particles such as fumed silica, silica, titania, alumina, zirconia, or a combination thereof. Barrier layers are described further in U.S. Pat. No. 6,001,522 to Woo et al., entitled “Barrier Layer For Photoconductor Elements Comprising An Organic Polymer And Silica,” incorporated herein by reference. The release layer topcoat may comprise any release layer composition known in the art. In some embodiments, the release layer is a fluorinated polymer, siloxane polymer, fluorosilicone polymer, silane, polyethylene, polypropylene, polyacrylate, or a combination thereof. The release layers can comprise crosslinked polymers. The release layer may comprise, for example, any release layer composition known in the art. In some embodiments, the release layer comprises a fluorinated polymer, siloxane polymer, fluorosilicone polymer, polysilane, polyethylene, polypropylene, polyacrylate, poly(methyl methacrylate-co-methacrylic acid), urethane resins, urethane-epoxy resins, acrylated-urethane resins, urethane-acrylic resins, or a combination thereof. In further embodiments, the release layers comprise crosslinked polymers. The protective layer can protect the organophotoreceptor from chemical and mechanical degradation. The protective layer may comprise any protective layer composition known in the art. In some embodiments, the protective layer is a fluorinated polymer, siloxane polymer, fluorosilicone polymer, polysilane, polyethylene, polypropylene, polyacrylate, poly(methyl methacrylate-co-methacrylic acid), urethane resins, urethane-epoxy resins, acrylated-urethane resins, urethane-acrylic resins, or a combination thereof. In some embodiments of particular interest, the release layers are crosslinked polymers. An overcoat layer may comprise an electron transport compound as described further in copending U.S. patent application Ser. No. 10/396,536, filed on Mar. 25, 2003 to Zhu et al. entitled, “Organoreceptor With An Electron Transport Layer,” incorporated herein by reference. For example, an electron transport compound, as described above, may be used in the release layer of this invention. The electron transport compound in the overcoat layer can be in an amount from about 2 to about 50 weight percent, and in other embodiments in an amount from about 10 to about 40 weight percent, based on the weight of the release layer. A person of ordinary skill in the art will recognize that additional ranges of composition within the explicit ranges are contemplated and are within the present disclosure. Generally, adhesive layers comprise a film forming polymer, such as polyester, polyvinylbutyral, polyvinylpyrrolidone, polyurethane, polymethyl methacrylate, poly(hydroxy amino ether) and the like. Barrier and adhesive layers are described further in U.S. Pat. No. 6,180,305 to Ackley et al., entitled “Organic Photoreceptors for Liquid Electrophotography,” incorporated herein by reference. Sub-layers can comprise, for example, polyvinylbutyral, organosilanes, hydrolyzable silanes, epoxy resins, polyesters, polyamides, polyurethanes, cellulosics, and the like. In some embodiments, the sub-layer has a dry thickness between about 20 Angstroms and about 20,000 Angstroms. Sublayers containing metal oxide conductive particles can be between about 1 and about 25 microns thick. A person of ordinary skill in the art will recognize that additional ranges of compositions and thickness within the explicit ranges are contemplated and are within the present disclosure. The charge transport materials as described herein, and photoreceptors including these compounds, are suitable for use in an imaging process with either dry or liquid toner development. For example, any dry toners and liquid toners known in the art may be used in the process and the apparatus of this invention. Liquid toner development can be desirable because it offers the advantages of providing higher resolution images and requiring lower energy for image fixing compared to dry toners. Examples of suitable liquid toners are known in the art. Liquid toners generally comprise toner particles dispersed in a carrier liquid. The toner particles can comprise a colorant/pigment, a resin binder, and/or a charge director. In some embodiments of liquid toner, a resin to pigment ratio can be from 1:1 to 10:1, and in other embodiments, from 4:1 to 8:1. Liquid toners are described further in Published U.S. Patent Applications 2002/0128349, entitled “Liquid Inks Comprising A Stable Organosol,” and 2002/0086916, entitled “Liquid Inks Comprising Treated Colorant Particles,” and U.S. Pat. No. 6,649,316, entitled “Phase Change Developer For Liquid Electrophotography,” all three of which are incorporated herein by reference. Charge Transport Material As described herein, an organophotoreceptor comprises a charge transport material having the formula where X1 and X2 are, each independently, a linking group, such as —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Rc, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group; R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one. With respect to Formula (I), substitution is liberally allowed, especially on X1, X2, and Ar. Variation of the substituents, such as an aromatic group, an alkyl group, a heterocyclic group, and a ring group such as a benzo group, on on X1, X2, and Ar can result in various physical effects on the properties of the compounds, such as mobility, solubility, compatibility, stability, spectral absorbance, dispersibility, and the like, including, for example, substitutions known in the art to effect particular modifications. In some embodiments, the organophotoreceptors as described herein can comprise an improved charge transport material of Formula (I) where X1 is a —Y4—CH2— group, and X2 is a —Y5—CH2CH(Y6H)CH2-Y1-Z1-Y2-Z2-Y3—CH2CH(Y7H)— group where Y1, Y2, Y3, Y4, Y5, Y6, and Y7 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1 and Z2, are, each independently, an aromatic group. In other embodiments, X1 is a —O—CH2— group, X2 is a —OCH2CH(OH)CH2—Y1-Z1-Y2-Z2-Y3—CH2CH(OH)— group. In further embodiments, X1 is a —O—CH2— group and X2 is a —OCH2CH(OH)CH2S—(C6H4)S(C6H4)SCH2CH(OH)— group. In additional embodiments, Ar is an aromatic C6H3 group; and R1 and R2, each independently, comprise an aromatic group, such as an [(N,N-disubstituted)amino]aryl group. Specific, non-limiting examples of suitable charge transport materials within Formula (I) of the present invention have the following structures: where n is a distribution of integers between 1 and 100,000 with an average value of greater than one. Synthesis of Charge Transport Materials The synthesis of the charge transport materials of this invention can be prepared by the following multi-step synthetic procedure, although other suitable synthetic procedures can be used by a person of ordinary skill in the art based on the disclosure herein. The letter groups in the structures shown in the synthetic procedure below are defined as follows: X1, X2, X3 and X4 are, each independently, a linking group, such as a —(CH2)m— group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRa group, a CRb group, a CRcRd group, or a SiReRf where Ra, Rb, Re, Rd, Re, and Rf are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group. Ar comprises an aromatic group. R1, R2, and R3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group. The term n is a distribution of integers between 1 and 100,000 with an average value of greater than one. Q1, Q2, Q3, and Q4 are, each independently, a functional group, such as a hydroxyl group, a thiol group, a carboxyl group, and an amino group, that reacts with a reactive ring group. E1 and E2 are, each independently, a reactive ring group, such as an epoxy group, a thiiranyl group, an aziridino group, and an oxetanyl group. General Synthetic Procedure The first step is the hydrazone formation reaction between an aldehyde or a ketone with an excess of hydrazine (H2N—NH2) to form the corresponding hydrazone of Formula (IV). The reaction can be catalyzed with acids, such as sulfuric acid and hydrochloric acid. In the second step, the hydrazone of Formula (IV) may react with an aromatic aldehyde or ketone having two functional groups (Q1 and Q2 that can react with a reactive ring group) to form the corresponding azine compound of Formula (III). Q1 and Q2 can be the same or different. In some embodiments, Q1 and Q2, each independently, are selected from the group consisting of hydroxyl group, thiol group, carboxyl group, and an amino group. The reaction can be catalyzed with acids, such as sulfuric acid and hydrochloric acid. In the third step, the azine compound of Formula (III) may react with at least an organic halide comprising one reactive ring group in the presence of an alkaline to form the corresponding azine compound of Formula (II) having two reactive ring groups (E1 and E2). E1 and E2 can be the same or different. If E1 and E2 are desired to be the same, one organic halide having one reactive ring group may be used. If E1 and E2 are desired to be different, the azine compound of Formula (III) may react with two different organic halides having one reactive ring group, either simultaneously or sequentially. The desired product may be isolated and purified by the convention purification techniques, such as column chromatography, thin layer chromatography, and recrystallization. The reactive ring group may be selected from the group consisting of heterocyclic ring groups which have a higher strain energy than its corresponding open-ring structure. The conventional definition of strain energy is that it represents the difference in energy between the actual molecule and a completely strain-free molecule of the same constitution. More information about the origin of strain energy can be found in the article by Wiberg et al., “A Theoretical Analysis of Hydrocarbon Properties: II Additivity of Group Properties and the Origin of Strain Energy,” J. Am. Chem. Soc. 109, 985 (1987). The above article is incorporated herein by reference. The heterocyclic ring group may have 3, 4, 5, 7, 8, 9, 10, 11, or 12 members, in further embodiments 3, 4, 5, 7, or 8 members, in some embodiment 3, 4, or 8 members, and in additional embodiments 3 or 4 members. Non-limiting examples of such heterocyclic ring are cyclic ethers (e.g., epoxides and oxetane), cyclic amines (e.g., aziridine), cyclic sulfides (e.g., thiirane), cyclic amides (e.g., 2-azetidinone, 2-pyrrolidone, 2-piperidone, caprolactam, enantholactam, and capryllactam), N-carboxy-α-amino acid anhydrides, lactones, and cyclosiloxanes. The chemistry of the above heterocyclic rings is described in George Odian, “Principle of Polymerization,” second edition, Chapter 7, p. 508-552 (1981), incorporated herein by reference. In some embodiments of interest, E1 and E2, each independently, are selected from the group consisting of an epoxy group, a thiiranyl group, an aziridino group, and an oxetanyl group. In some embodiments, at least one of the E1 and E2 groups is an epoxy group. Non-limiting examples of suitable organic halide comprising an epoxy group as the reactive ring group are epihalohydrins, such as epichlorohydrin. The organic halide comprising an epoxy group can also be prepared by the epoxidation reaction of the corresponding alkene having a halide group. Such epoxidation reaction is described in Carey et al., “Advanced Organic Chemistry, Part B: Reactions and Synthesis,” New York, 1983, pp. 494-498, incorporated herein by reference. The alkene having a halide group can be prepared by the Wittig reaction between a suitable aldehyde or keto compound and a suitable Wittig reagent. The Wittig and related reactions are described in Carey et al., “Advanced Organic Chemistry, Part B: Reactions and Synthesis,” New York, 1983, pp. 69-77, which is incorporated herein by reference. The various preparation procedures of epoxy compounds have been disclosed in U.S. patent application Ser. Nos. 10/749,178, 10/634,164, 10/695,581, 10/663,970, and 10/692,389, and U.S. Provisional Patent Application Nos. 60/444,001 and 60/459,150. All the above application references are incorporated herein by reference. In other embodiments, at least one of the E1 and E2 groups is a thiiranyl group. An epoxy compound, such as those described above, can be converted into the corresponding thiiranyl compound by refluxing the epoxy compound and ammonium thiocyanate in tetrahydrofuran. Alternatively, the corresponding thiiranyl compound may be obtained by passing a solution of the above-described epoxy compound through 3-(thiocyano)propyl-functionalized silica gel (commercially available form Aldrich, Milwaukee, Wis.). Alternatively, a thiiranyl compound may be obtained by the thia-Payne rearrangement of a corresponding epoxy compound. The thia-Payne rearrangement is described in Rayner, C. M. Synlett 1997, 11; Liu, Q. Y.; Marchington, A. P.; Rayner, C. M. Tetrahedron 1997, 53, 15729; Ibuka, T. Chem. Soc. Rev. 1998, 27, 145; and Rayner, C. M. Contemporary Organic Synthesis 1996, 3, 499. All the above four articles are incorporated herein by reference. In further embodiments, at least one of the E1 and E2 groups is an aziridinyl group. An aziridine compound may be obtained by the aza-Payne rearrangement of a corresponding epoxy compound, such as one of those epoxy compounds described above. The thia-Payne rearrangement is described in Rayner, C. M. Synlett 1997, 11; Liu, Q. Y.; Marchington, A. P.; Rayner, C. M. Tetrahedron 1997, 53, 15729; and Ibuka, T. Chem. Soc. Rev. 1998, 27, 145. All the above three articles are incorporated herein by reference. Alternatively, an aziridine compound may be prepared by the addition reaction between a suitable nitrene compound and a suitable alkene. Such addition reaction is described in Carey et al., “Advanced Organic Chemistry, Part B: Reactions and Synthesis,” New York, 1983, pp. 446-448, incorporated herein by reference. In additional embodiments, at least one of the E1 and E2 groups is an oxetanyl group. An oxetane compound may be prepared by the Paterno-Buchi reaction between a suitable carbonyl compound and a suitable alkene. The Paterno-Buchi reaction is described in Carey et al., “Advanced Organic Chemistry, Part B: Reactions and Synthesis,” New York, 1983, pp. 335-336, incorporated herein by reference. The order of Steps 1-3 may be modified by a person of ordinary skill in the art based on the disclosure herein. For example, Step 1 and Step 2 may be reversed. In the other words, the aromatic aldehyde or ketone having two functional groups may react first with an excess of hydrazine to form the corresponding hydrazone, which then reacts with the aldehyde or ketone to form the corresponding azine of Formula (III). Another example is that Step 2 and Step 3 may be reversed so that the aromatic aldehyde or ketone having two reactive functional groups may react with an organic halide first and then with the hydrazone of Formula (IV) to form the corresponding azine of Formula (II). The fourth step is the co-polymerization of the corresponding azine compound of Formula (II) having two reactive ring groups (E1 and E2) with a bridging compound (Q3-Z-Q4) in the presence of triethylamine to form the corresponding charge transport material of Formula (I). The bridging compound has a bridging group Z and at least two functional groups (Q3 and Q4), such as a hydroxyl group, a thiol group, an amino group, and a carboxyl group, that are reactive towards the reactive ring groups E1 and E2. Non-limiting examples of the bridging group Z include —(CH2)k— groups, where k is an integer between 1 and 30, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NRm group, a CRn group, a CRoRp group, or a SiRqRr where Rm, Rn, Ro, Rp, Rq, and Rr are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group. The bridging compound may be a diol, a dithiol, a diamine, a dicarboxylic acid, a hydroxylamine, an amino acid, a hydroxyl acid, a thiol acid, a hydroxythiol, or a thioamine. Non-limiting examples of suitable dithiol are 4,4′-thiobisbenzenethiol, 1,4-benzenedithiol, 1,3-benzenedithiol, sulfonyl-bis(benzenethiol), 2,5-dimecapto-1,3,4-thiadiazole, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, and 1,6-hexanedithiol. Non-limiting examples of suitable diols are 2,2′-bi-7-naphtol, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 10,10-bis(4-hydroxyphenyl)anthrone, 4,4′-sulfonyldiphenol, bisphenol, 4,4′-(9-fluorenylidene)diphenol, 1,10-decanediol, 1,5-pentanediol, diethylene glycol, 4,4′-(9-fluorenylidene)-bis(2-phenoxyethanol), bis(2-hydroxyethyl) terephthalate, bis[4-(2-hydroxyethoxy)phenyl] sulfone, hydroquinone-bis (2-hydroxyethyl)ether, and bis(2-hydroxyethyl) piperazine. Non-limiting examples of suitable diamine are diaminoarenes, and diaminoalkanes. Non-limiting examples of suitable dicarboxylic acid are phthalic acid, terephthalic acid, adipic acid, and 4,4′-biphenyldicarboxylic acid. Non-limiting examples of suitable hydroxylamine are p-aminophenol and fluoresceinamine. Non-limiting examples of suitable amino acid are 4-aminobutyric acid, phenylalanine, and 4-aminobenzoic acid. Non-limiting examples of suitable hydroxyl acid are salicylic acid, 4-hydroxybutyric acid, and 4-hydroxybenzoic acid. Non-limiting examples of suitable hydroxythiol are monothiohydroquinone and 4-mercapto-1-butanol. Non-limiting example of suitable thioamine is p-aminobenzenethiol. Non-limiting example of suitable thiol acid are 4-mercaptobenzoic acid and 4-mercaptobutyric acid. Almost all of the above bridging compounds are available commercially from Aldrich and other chemical suppliers. X1 and X2 in Formula (I) are produced by the two ring-opening reactions between X3-E1 and Q3, and between X4-E2 and Q4. X1 and X2 may be parsed based on X3, E1, Q3, X4, E2, and Q4 in many different ways reasonable to a person skill in the art. A non-limiting example of reasonable parsing is that X1 is X3-E1′-Q3′ where E1′-Q3′ is the ring-opening reaction product between E1 and Q3; and X2 is X4-E2′-Q4′-Z where E2′-Q4′ is the ring-opening reaction product between E2 and Q4. Another non-limiting example of reasonable parsing is that X1 is X3; and X2 is X4-E2′-Q4′-Z-Q′3-E′1 where E2′-Q4′ is the ring-opening reaction product of E2 and Q4 and E1′-Q3′ is the ring-opening reaction product between E1 and Q3. In some embodiments, Z comprises a Y1-Z1-Y2-Z2-Y3— group where Y1, Y2, and Y3 are, each independently, O, S, or NR where R is H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and Z1, and Z2, are, each independently, an aromatic group. In further embodiments, Y1, Y2, and Y3 are, each independently, S; and Z1, and Z2, are, each independently, a phenylene group. Although ring-opening reactions between reactive ring groups and functional groups that are reactive toward the reactive ring groups are disclosed in the fourth step above for the co-polymerization, other suitable synthetic reactions between two different functional groups that are reactive toward each other may be utilized for the co-polymerization in the fourth step. For example, Q3 and Q4 may be, each independently, hydroxyl or amine groups (or, each independently, carboxylic acid or halide groups) and E1 and E2 may be, each independently, carboxylic acid or halide groups (or, each independently, hydroxyl or amine groups) that react with the hydroxyl or amine groups (or carboxylic acid or halide groups) to produce a charge transport material of Formula (I) where X1 and X2 comprise, each independently, an ester or amide group respectively, or a combination thereof. Another example is that Q3 and Q4 may be amino groups (or carbonyl groups) and E1 and E2 may be carbonyl groups (or amino groups) that react with the amino groups (or carbonyl groups) to produce a charge transport material of Formula (I) where X1 and X2 comprise, each independently, an imine group. A further example is that Q3 and Q4 may be isocyanate groups (or, each independently, hydroxyl, thiol, or amine groups) and E1 and E2 may be, each independently, hydroxyl, thiol, or amine groups (or isocyanate groups) that react with the isocyanate groups (or hydroxyl, thiol, or amine groups) to produce a charge transport material of Formula (I) where X1 and X2 comprise, each independently, a urethane, thiocarbamate, or urea group respectively, or a combination thereof. Other suitable reactions can be used by a person of ordinary skill in the art based on the disclosure herein. The invention will now be described further by way of the following examples. EXAMPLES Example 1 Synthesis and Characterization Charge Transport Materials This example describes the synthesis and characterization of Compound (1). The characterization involves chemical characterization of the compound. The electrostatic characterization, such as mobility and ionization potential, of the materials formed with the compound is presented in a subsequent example. Bis(4,4′-diethylamino)benzophenone Hydrazone A solution of bis(4,4′-diethylamino)benzophenone (108.1 g, 0.335 mol, from Aldrich), hydrazine monohydrate (98%, 244 ml, 5 mol, from Aldrich), and 10 ml of concentrated hydrochloric acid (from Aldrich) in 250 ml of 2-propanol was added to a 1000 ml 3-neck round bottom flask equipped with a reflux condenser and a mechanical stirrer. The solution was refluxed for approximately 6 hours with an intensive stirring until bis(4,4′-diethylamino)benzophenone disappeared. The solution was allowed to stand overnight. The crystals that formed upon standing were removed by filtration and then washed with 2-propanol to yield 79.2 g (70%) of bis(4,4′-diethylamino)benzophenone hydrazone. The melting point of the product was found to be 124-126° C. (recrystallized from 2-propanol). The 1H-NMR spectrum (100 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 7.37 (d, J=9.0 Hz, 2H, Ar); 7.14 (d, J=8.8 Hz, 2H, Ar); 6.74 (d, J=8.8 Hz, 2H, Ar); 6.58 (d, J=9.0 Hz, 2H, Ar); 4.85 (s, br, 2H, NH2); 3.36 (m, 8H, N(CH2CH3)2; and 1.17 (m, 12H, N(CH2CH3)2). An elemental analysis yielded the following results in weight percent: C, 74.49; H, 7.68; N, 15.12, which compared with the following calculated values for C21H30N4 in weight percent: C, 74.52; H, 8.93; N, 16.55. 4,4′-Bis(diethylamino)benzophenone 2,4-Dihydroxybenzaldehyde Azine A mixture of bis(4,4′-diethylamino)benzophenone hydrazone (33.6 g, 0.1 mol, obtained previously), 2,4-dihydroxybenzaldehyde (15.1 g, 0.1 mol, obtained from Aldrich) and 40 ml of methanol was added to a 100 ml 3-neck round bottom flask equipped with a reflux condenser and a mechanical stirrer. The mixture was refluxed for 0.5 hour until one of the starting material disappeared. The solution was cooled to room temperature. The crystals formed in the cooled solution were filtered and washed repeatedly with methanol and dried at 50° C. in a vacuum oven for 5 hours to yield 36 g (79%) of crude product. The product was recrystallized from a mixture of dioxane and methanol in a volume ratio of 1:2. The product had a melting point of 205-206.5° C. The 1H-NMR spectrum (100 MHz) of the product in CDCl3 and two drops of DMSO-d6 was characterized by the following chemical shifts (δ, ppm): 11.74 (s, 1H, OH); 9.44 (s, 1H, OH); 8.55 (s, 1H, N═CH); 7.51 (d, 2H, Ar); 7.35-6.98 (m, 3H, Ar); 6.80-6.48 (m, 4H, Ar); 6.48-6.18 (m, 2H, Ar); 3.35 (q, 8H, CH2CH3, J=7.5 Hz); and 1.15 (m, 12H, CH2CH3). An elemental analysis yielded the following results in weight percent: C, 73.11; H, 7.28; N, 12.10 which, compared with calculated values for C28H34N4O2 in weight percent of: C, 73.33; H 7.47; N 12.22. 4,4′-Bis(diethylamino)benzophenone 2,4-Bis(1,2-epoxypropoxy)benzaldehyde Azine A mixture of 4,4′-bis(diethylamino)benzophenone 2,4-dihydroxybenzaldehyde_azine (33 g, 0.072 mol) and epichlorohydrin (85 ml, 1.1 mmol, commercially available from Aldrich) was stirred vigorously at 30-35° C. for 5 hours until the starting dihydroxy compound and its monosubstituted compound disappeared. During the 5-hour period, 12.2 g (0.22 mol) of powdered 85% potassium hydroxide and 3.6 g (28.8 mmol) of anhydrous sodium sulfate were added in three portions while the reaction mixture was kept at 20-25° C. After the termination of the reaction, the mixture was cooled to room temperature and filtered. The organic filtrate was treated with ethyl acetate and washed with distilled water until the washed water reached a neutral pH. Then, the organic layer was dried over anhydrous magnesium sulfate, treated with activated charcoal, and filtered. The solvents were removed and the residue was subjected to chromatography (silica gel, grade 62, 60-200 mesh, 150 Å, obtained from Aldrich) using a mixture of acetone and hexane in a volume ratio of 1:4 as the eluant. Fractions containing the product were collected and evaporated to yield 25.0 g (63%) of an oily residue. The oily residue crystallized after standing at room temperature for one month. The 1H-NMR spectrum (100 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 8.95 (s, 1H, CH═N); 8.02-7.18 (m, 5H, Ar); 6.80-6.32 (m, 6H, Ar); 4.44-3.64 (m, 6H, OCH2CH); 3.39 (q, 8H, N(CH2CH3)2); 3.04-2.68 (m, 4H, CH2 of oxirane); and 1.22 (m, 12H, N(CH2CH3)2). An elemental analysis yielded the following results in weight percent: C, 71.37; H, 7.28; and N, 9.65, which compared with calculated values for C34H42N4O4 in weight percent of: C, 71.55; H, 7.42; and N, 9.82. Compound (1) A mixture of 4,4′-bis(diethylamino)benzophenone 2,4-bis(1,2-epoxypro-poxy)benzaldehyde azine (1.61 g, 2.83 mmol), 4,4′-thiobisbenzenethiol (0.709 g, 2.8 mmol, from Aldrich, Milwaukee, Wis.) and triethylamine (0.2 ml, 1.415 mmol, from Aldrich, Milwaukee, Wis.) was refluxed in 20 ml of tetrahydrofuran (THF) under argon for 60 hours. The reaction mixture was cooled to room temperature and filtered through a layer of silica gel (3-4 cm thick, grade 62, 60-200 mesh, 150 Å) and the silica gel was washed with THF. The THF solution was concentrated to 15-20 ml by evaporation and then poured into 20-fold excess of methanol with intensive stirring. The resulted precipitate was filtered off and washed repeatedly with methanol and dried in a vacuum oven at 50° C. for 5 hours. The yield of the product was 1.4 g (60.4%). Example 2 Charge Mobility Measurements This example describes the measurement of charge mobility and ionization potential for charge transport materials, specifically Compound (1) above. Sample 1 A mixture of 0.1 g of the Compound (1) and 0.1 g of polycarbonate Z was dissolved in 2 ml of tetrahydrofuran. The solution was coated on a polyester film with a conductive aluminum layer by a dip roller. After the coating was dried for 1 hour at 80° C., a clear 10 μm thick layer was formed. The hole mobility of the sample was measured and the results are presented in Table 1. Mobility Measurements Each sample was corona charged positively up to a surface potential U and illuminated with 2 ns long nitrogen laser light pulse. The hole mobility μ was determined as described in Kalade et al., “Investigation of charge carrier transfer in electrophotographic layers of chalkogenide glasses,” Proceeding IPCS 1994: The Physics and Chemistry of Imaging Systems, Rochester, N.Y., pp. 747-752, incorporated herein by reference. The hole mobility measurement was repeated with appropriate changes to the charging regime to charge the sample to different U values, which corresponded to different electric field strength inside the layer E. This dependence on electric field strength was approximated by the formula μ=μ0eα{square root}{square root over (E)} Here E is electric field strength, μ0 is the zero field mobility and α is Pool-Frenkel parameter. Table 1 lists the mobility characterizing parameters μ0 and α values and the mobility value at the 6.4x105 V/cm field strength as determined by these measurements for the four samples. TABLE 1 Ionization μ0 μ(cm2/V · s) α Potential Sample (cm2V · s) at 6.4 · 105 V/cm (cm/V)0.5 (eV) Sample 1/ 3.0 × 10−12 1.7 × 10−9 ˜0.0079 5.42 Compound (1) Example 3 Ionization Potential Measurements This example describes the measurement of the ionization potential for the charge transport material described in Example 1. To perform the ionization potential measurements, a thin layer of charge transport material about 0.5 μm thickness was coated from a solution of 2 mg of charge transport material in 0.2 ml of tetrahydrofuran on a 20 cm2 substrate surface. The substrate was an aluminized polyester film coated with a 0.4 μm thick methylcellulose sub-layer. Ionization potential was measured as described in Grigalevicius et al., “3,6-Di(N-diphenylamino)-9-phenylcarbazole and its methyl-substituted derivative as novel hole-transporting amorphous molecular materials,” Synthetic Metals 128 (2002), p. 127-131, incorporated herein by reference. In particular, each sample was illuminated with monochromatic light from the quartz monochromator with a deuterium lamp source. The power of the incident light beam was 2-5·10−8 W. A negative voltage of −300 V was supplied to the sample substrate. A counter-electrode with the 4.5×15 mm2 slit for illumination was placed at 8 mm distance from the sample surface. The counter-electrode was connected to the input of a BK2-16 type electrometer, working in the open input regime, for the photocurrent measurement. A 10−15-10−12 amp photocurrent was flowing in the circuit under illumination. The photocurrent, I, was strongly dependent on the incident light photon energy hν. The I0.5=f(hν) dependence was plotted. Usually, the dependence of the square root of photocurrent on incident light quanta energy is well described by linear relationship near the threshold (see references “Ionization Potential of Organic Pigment Film by Atmospheric Photoelectron Emission Analysis,” Electrophotography, 28, Nr. 4, p. 364 (1989) by E. Miyamoto, Y. Yamaguchi, and M. Yokoyama; and “Photoemission in Solids,” Topics in Applied Physics, 26, 1-103 (1978) by M. Cordona and L. Ley, both of which are incorporated herein by reference). The linear part of this dependence was extrapolated to the hν axis, and the Ip value was determined as the photon energy at the interception point. The ionization potential measurement has an error of ±0.03 eV. The ionization potential value is given in Table 1 above. As understood by those skilled in the art, additional substitution, variation among substituents, and alternative methods of synthesis and use may be practiced within the scope and intent of the present disclosure of the invention. The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the claims. Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>In electrophotography, an organophotoreceptor in the form of a plate, disk, sheet, belt, drum or the like having an electrically insulating photoconductive element on an electrically conductive substrate is imaged by first uniformly electrostatically charging the surface of the photoconductive layer, and then exposing the charged surface to a pattern of light. The light exposure selectively dissipates the charge in the illuminated areas where light strikes the surface, thereby forming a pattern of charged and uncharged areas, referred to as a latent image. A liquid or solid toner is then provided in the vicinity of the latent image, and toner droplets or particles deposit in the vicinity of either the charged or uncharged areas to create a toned image on the surface of the photoconductive layer. The resulting toned image can be transferred to a suitable ultimate or intermediate receiving surface, such as paper, or the photoconductive layer can operate as an ultimate receptor for the image. The imaging process can be repeated many times to complete a single image, for example, by overlaying images of distinct color components or effect shadow images, such as overlaying images of distinct colors to form a full color final image, and/or to reproduce additional images. Both single layer and multilayer photoconductive elements have been used. In single layer embodiments, a charge transport material and charge generating material are combined with a polymeric binder and then deposited on the electrically conductive substrate. In multilayer embodiments, the charge transport material and charge generating material are present in the element in separate layers, each of which can optionally be combined with a polymeric binder, deposited on the electrically conductive substrate. Two arrangements are possible for a two-layer photoconductive element. In one two-layer arrangement (the “dual layer” arrangement), the charge-generating layer is deposited on the electrically conductive substrate and the charge transport layer is deposited on top of the charge generating layer. In an alternate two-layer arrangement (the “inverted dual layer” arrangement), the order of the charge transport layer and charge generating layer is reversed. In both the single and multilayer photoconductive elements, the purpose of the charge generating material is to generate charge carriers (i.e., holes and/or electrons) upon exposure to light. The purpose of the charge transport material is to accept at least one type of these charge carriers and transport them through the charge transport layer in order to facilitate discharge of a surface charge on the photoconductive element. The charge transport material can be a charge transport compound, an electron transport compound, or a combination of both. When a charge transport compound is used, the charge transport compound accepts the hole carriers and transports them through the layer with the charge transport compound. When an electron transport compound is used, the electron transport compound accepts the electron carriers and transports them through the layer with the electron transport compound. Organophotoreceptors may be used for both dry and liquid electrophotography. There are many differences between dry and liquid electrophotography. A significant difference is that a dry toner is used in dry electrophotography, whereas a liquid toner is used in liquid electrophotography. A potential advantage of liquid electrophotography is that it can provide a higher resolution and thus sharper images than dry electrophotography because liquid toner particles can be generally significantly smaller than dry toner particles. As a result of their smaller size, liquid toners are able to provide images of higher optical density than dry toners. In liquid electrophotography, the organophotoreceptor is in contact with the liquid carrier of a liquid toner while the toner dries or pending transfer to a receiving surface. As a result, the charge transport material in the photoconductive element may be removed by extraction by the liquid carrier. Over a long period of operation, the amount of the charge transport material removed by extraction may be significant and, therefore, detrimental to the performance of the organophotoreceptor. | <SOH> SUMMARY OF THE INVENTION <EOH>This invention provides organophotoreceptors having good electrostatic properties such as high V acc and low V dis . This invention also provides organophotoreceptors comprising a charge transport material having reduced extraction by liquid carriers. In a first aspect, an organophotoreceptor comprises an electrically conductive substrate and a photoconductive element on the electrically conductive substrate, the photoconductive element comprising: (a) a charge transport material comprising a polymer having the formula: where X 1 and X 2 are, each independently, a linking group, such as —(CH 2 ) m — group, where m is an integer between 1 and 20, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NR a group, a CR b group, a CR c R d group, or a SiR e R f where R a , R b , R c , R d , R e , and R f are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group, such as an aromatic C 6 H 3 group; R 1 , R 2 , and R 3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and n is a distribution of integers between 1 and 100,000 with an average value of greater than one; and (b) a charge generating compound. The asterisks (*) indicate terminal groups of the polymer of Formula (I), which may vary between different polymer units depending on the state of the particular polymerization process at the end of the polymerization step. The organophotoreceptor may be provided, for example, in the form of a plate, a flexible belt, a flexible disk, a sheet, a rigid drum, or a sheet around a rigid or compliant drum. In one embodiment, the organophotoreceptor includes: (a) a photoconductive element comprising the charge transport material, the charge generating compound, a second charge transport material, and a polymeric binder; and (b) the electrically conductive substrate. In a second aspect, the invention features an electrophotographic imaging apparatus that comprises (a) a light imaging component; and (b) the above-described organophotoreceptor oriented to receive light from the light imaging component. The apparatus can further comprise a toner dispenser, such as a liquid toner dispenser. The method of electrophotographic imaging with photoreceptors containing the above noted charge transport materials is also described. In a third aspect, the invention features an electrophotographic imaging process that includes (a) applying an electrical charge to a surface of the above-described organophotoreceptor; (b) imagewise exposing the surface of the organophotoreceptor to radiation to dissipate charge in selected areas and thereby form a pattern of at least relatively charged and uncharged areas on the surface; (c) contacting the surface with a toner, such as a liquid toner that includes a dispersion of colorant particles in an organic liquid, to create a toned image; and (d) transferring the toned image to a substrate. In a fourth aspect, the invention features a charge transport material comprising a polymer having Formula (I) above. In a fifth aspect, the invention features a method for forming a polymeric charge transport material, the method comprising the step of co-polymerizing a bridging compound having a bridging group and at least two functional groups with a charge transport material having the formula: where X 3 and X 4 are, each independently, a linking group, such as a —(CH 2 ) p — group, where p is an integer between 1 and 10, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NR g group, a CR h group, a CR i R j group, or a SiR k R 1 where R g , R h , R i , R j , R k , and R l are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group; Ar comprises an aromatic group, such as an aromatic C 6 H 3 group; R 1 , R 2 , and R 3 comprise, each independently, H, an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, or a heterocyclic group; and E 1 and E 2 are, each independently, a reactive ring group, such as an epoxy group, a thiiranyl group, an aziridino group, and an oxetanyl group. In some embodiments, the bridging group is a —(CH 2 ) k — group, where k is an integer between 1 and 30, inclusive, and one or more of the methylene groups is optionally replaced by O, S, N, C, B, Si, P, C═O, O═S═O, an NR m group, a CR n group, a CR o R p group, or a SiR q R r where R m , R n , R o , R p , R q , and R r are, each independently, a bond, H, a hydroxyl group, a thiol group, a carboxyl group, an amino group, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heterocyclic group, an aromatic group, or a part of a ring group, such as cycloalkyl groups or a benzo group. In other embodiments, the functional groups, each independently, are a hydroxyl group, a thiol group, a carboxyl group, and an amino group. The invention provides suitable charge transport materials for organophotoreceptors featuring a combination of good chemical and electrostatic properties. These photoreceptors can be used successfully with toners, including liquid toners, to produce high quality images. The high quality of the imaging system can be maintained after repeated cycling. Other features and advantages of the invention will be apparent from the following description of the particular embodiments thereof, and from the claims. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20080122 | 20051006 | 75028.0 | 0 | GOODROW, JOHN L | POLY(AZINE)-BASED CHARGE TRANSPORT MATERIALS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,939 | ACCEPTED | Ice detector for improved ice detection at near freezing condition | An ice detector for providing a signal indicating ice formation includes a probe protruding into an airflow. The probe extends into the airflow from a strut. The strut has one or more features which allow the probe to accrete ice at a higher temperature than would conventionally be possible. Strut features can include a notch formed therein in an upwind direction relative to the probe, and a curved surface adjacent a point of extension of the probe from the strut. | 1. An ice detector for providing a signal indicating ice formation, the ice detector comprising: a probe protruding into an airflow; and a strut from which the probe extends into the airflow, the strut having a notch formed therein in an upwind direction relative to the probe. 2. The ice detector of claim 1, wherein the notch is disposed and arranged such that it causes the airflow to increase in turbulence prior to reaching the probe, thereby increasing heat transfer from the probe to lower the actual temperature of the probe. 3. The ice detector of claim 2, wherein the notch is formed as a cylindrical shaped cavity in a surface of the strut adjacent to a point of extension of the probe from the strut. 4. The ice detector of claim 2, wherein the notch is formed as a v-shaped cavity. 5. The ice detector of claim 2, wherein the notch is formed as a rectangular shaped cavity. 6. The ice detector of claim 2, wherein the surface of the strut adjacent to the point of extension of the probe is a curved surface that accelerates the airflow before it reaches the probe. 7. The ice detector of claim 2, and further comprising a mounting flange to which the strut is coupled, the mounting flange being configured to be fixed to a surface of an aircraft. 8. The ice detector of claim 7, wherein the probe extends from the strut at an inclined angle relative to a direction that is perpendicular to the mounting flange. 9. The ice detector of claim 2, wherein the probe has a longitudinally extending shape. 10. The ice detector of claim 9, wherein the probe has a substantially cylindrical shape. 11. The ice detector of claim 9, wherein the probe has an ice accreting edge at a distal end of the probe. 12. The ice detector of claim 11, wherein the probe further comprises a flat tip at the distal end of the probe providing the ice accreting edge. 13. The ice detector of claim 9, wherein the probe is a magnetostrictive probe. 14. The ice detector of claim 13, and further comprising excitation and sensing circuitry which vibrates the probe and detects changes in a frequency of vibration of the probe caused by accretion of ice on the probe. 15. An ice detector for providing a signal indicating ice formation, the ice detector comprising: a probe protruding into an airflow; a strut from which the probe extends into the airflow, the strut having a curved surface adjacent a point of extension of the probe from the strut, the curved surface being positioned in an upwind direction relative to the probe to accelerate the airflow before it reaches the probe. 16. The ice detector of claim 15, wherein the probe has a longitudinally extending shape and an ice accreting edge at a distal end of the probe. 17. The ice detector of claim 16, wherein the probe further comprises a flat tip at the distal end of the probe providing the ice accreting edge. 18. The ice detector of claim 15, wherein the probe has a substantially cylindrical shape. 19. The ice detector of claim 15, wherein the strut has a notch formed therein in the upwind direction relative to the probe, the notch being disposed and arranged such that it causes the airflow to increase in turbulence prior to reaching the probe, thereby increasing heat transfer from the probe to lower an actual temperature of the probe. 20. The ice detector of claim 19, wherein the notch is formed as a cylindrical shaped cavity in the curved surface. 21. The ice detector of claim 15, wherein the probe is a magnetostrictive probe, the ice detector further comprising excitation and sensing circuitry which vibrates the probe and detects changes in a frequency of vibration of the probe caused by accretion of ice on the probe. | CROSS-REFERENCE TO RELATED APPLICATIONS Reference is hereby made to the following co-pending and commonly assigned patent application filed on even date herewith: U.S. Application Serial No. ______ entitled “ICE DETECTOR FOR IMPROVED ICE DETECTION AT NEAR FREEZING CONDITION”, which is incorporated by reference in its entirety. BACKGROUND OF THE INVENTION The present invention relates to vibrating type ice detectors for use with aircraft and in any other locations where the detection of ice is of importance. More particularly, the present invention relates to ice detector configurations that increase the critical temperature limit of an ice detector probe to provide earlier ice detection. Existing ice detectors are useful in near freezing temperature conditions for detecting the formation of ice on the detector, and providing a warning of the ice formation prior to the formation of ice on the wings, engine nacelles, and other control surfaces of an aircraft. A frequently used type of ice detector is a vibrating ice detector. Vibrating type ice detectors use a vibrating probe upon which ice accumulates. Typically, the probe is a cylindrical probe having a hemispherical end. Examples of vibrating type ice detectors are described, for example, in U.S. Pat. Nos. 3,341,835 entitled ICE DETECTOR by F. D. Werner et al.; 4,553,137 entitled NON-INSTRUSIVE ICE DETECTOR by Marxer et al.; 4,611,492 entitled MEMBRANE TYPE NON-INTRUSIVE DETECTOR by Koosmann; 6,269,320 entitled SUPERCOOLED LARGE DROPLET ICE DETECTOR by Otto; and 6,320,511 entitled ICE DETECTOR CONFIGURATION FOR IMPROVED ICE DETECTION AT NEAR FREEZING CONDITIONS by Cronin et al., which are herein incorporated by reference in their entirety. The ability of ice detectors to provide a warning of ice formation prior to formation of ice on the wings, engine nacelles, or other control surface of an aircraft is dependent upon the critical temperature of the ice detector probe and the critical temperature of the aircraft wings or control surface. The critical temperature is defined as the ambient static temperature at or above which none of the supercooled liquid water droplets in a cloud will freeze when they impinge on a structure. Stated another way, the critical temperature is the temperature above which no ice will form (or below which ice will form) on a structure (such as an aircraft wing or an ice detector probe) given its configuration and other atmospheric conditions. The critical temperature can be different for different structures, and specifically for a typical airfoil configuration and for a conventional ice detector, at the same airspeed. Since the critical temperature of an ice detector probe is the temperature below which ice will begin to form on the probe, thus defining the upper temperature limit at which the ice detector will not detect icing conditions, it is of significant interest in the design of ice detectors. Ensuring that the critical temperature of the ice detector probe is above the critical temperature of the wings or other control surfaces of an aircraft is a continuing challenge, particularly with newer airfoil designs. Therefore, a vibrating type ice detector having a probe with an increased critical temperature would be a significant improvement in the art. Other ice accretion improving features would similarly be significant improvements in the ice detector art. The present invention addresses one or more of the above-identified problems and/or provides other advantages over prior art ice detectors. SUMMARY OF THE INVENTION An ice detector for providing a signal indicating ice formation includes a probe protruding into an airflow. The probe extends into the airflow from a strut. The strut has one or more features which allow the probe to accrete ice at a higher temperature than would conventionally be possible. Also, the probe can include surface roughness features that further improve ice detection. Surface roughness features on the probe include ice accreting edges at a distal end of the probe and features arranged on a side surface of the probe which cause the airflow to increase in turbulence, thereby decreasing the temperature of the probe. Decreasing the temperature of the probe, along with increasing the critical temperature of the probe, improves ice accretion on the probe, and thereby ice detection. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary schematic front view of an aircraft having an ice detector made according to the present invention installed thereon. FIG. 2-1 is a side view of an ice detector made according to an embodiment of the present invention. FIG. 2-2 is a top view of the ice detector illustrated in FIG. 2-1. FIG. 2-3 is a rear view of the ice detector illustrated in FIGS. 2-1 and 2-2. FIG. 3 is a plot illustrating critical temperature difference as a function of true airspeed for one exemplary ice detector in accordance with the present invention. FIG. 4 is a plot illustrating critical static temperature as a function of true airspeed for both a conventional ice detector and for an ice detector in accordance with the present invention. FIGS. 5-1 and 5-2 are diagrammatic illustrations of an alternate probe configuration in accordance with some embodiments of ice detectors of the present invention. FIGS. 6-1 and 6-2 are diagrammatic illustrations of a second alternate probe configuration in accordance with some embodiments of ice detectors of the present invention. FIGS. 7-1 and 7-2 are diagrammatic illustrations of a third alternate probe configuration in accordance with some embodiments of the ice detectors of the present invention. FIGS. 8-1 and 8-2 are diagrammatic illustrations of a fourth alternate probe configuration in accordance with some embodiments of the ice detectors of the present invention. FIGS. 9-1 though 9-4 are diagrammatic illustrations of further alternate probe modifications, in accordance with other embodiments of the ice detectors of the present invention, which can be used to increase the critical temperature of the probe. FIGS. 10-1 through 10-5 are diagrammatic illustrations of alternate probe tip configurations that can be used in embodiments of the ice detectors of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a typical aircraft indicated at 10 is of conventional design, and includes an airfoil cross-section shaped wing 12. An ice detector probe assembly 14 (ice detector 14), made according to the present invention, is supported on the skin or outer wall 16 of the aircraft. The ice detector 14 is positioned relative to the wing 12 at a known location that is selected to provide for detection of ice as air flows past the wing and the aircraft skin 16. FIGS. 2-1 through 2-3 illustrate an embodiment of the ice detector 14 in accordance with the present invention. As shown, ice detector 14 includes a generally cylindrical probe 20 mounted onto a strut 30. Strut 30 is fixed to a mounting flange 42, which is supported by the aircraft skin 16 (not shown in FIGS. 2-2 and 2-3). A housing 46, typically located on the interior of the aircraft below skin 16, houses suitable excitation and sensing circuitry illustrated generally at 50, which is of conventional design. As in conventional vibrating type ice detectors, probe 20 may be of the magnetostrictive type, and is vibrated, in directions as indicated by the double arrow 22, by the excitation porting of circuitry 50. The sensing portion of the circuitry 50 will detect any change in the natural frequency of vibration caused by ice accretion on the surface of the probe 20. Surface temperature of an object such as probe 20 is related to the velocity at which fluid flows past it. A first aspect of the present invention is based in part upon the recognition that this effect can be used to lower the static temperature of the surface of the ice detector probe 20. To this end, strut 30 includes a curved forward upper surface 32. Curved forward upper surface 32 of strut 30 is positioned in front of probe 20 such that airflow, which approaches probe 20 traveling generally in the direction represented by arrow 60, passes by curved forward upper surface 32 before reaching probe 20. Curved forward upper surface 32 accelerates the airflow before it reaches probe 20, thereby lowering the static temperature of the surface of probe 20. This in turn increases the critical temperature of probe 20, allowing ice to form on probe 20 prior to its formation on the wings of the aircraft. Surface roughness and surface disturbances can cause the boundary layer of a fluid near a surface to become turbulent or separate, changing the heat transfer from the surface. Generally, turbulent airflow improves heat transfer. Specifically, increasing the amount of turbulence in the fluid surrounding it increases heat transfer from a cylinder, such as probe 20. A second aspect of the present invention is based in part upon the recognition that this effect can be used to lower the overall temperature of probe 20. In accordance with this second aspect of the present invention, a cut or step 34 is formed in strut 30 ahead of probe 20. This cut or step 34, which is also referred to as a notch, is illustrated in FIG. 2-2, and is represented diagrammatically in FIG. 2-1 by dashed lines 36. In an exemplary embodiment, the notch is a circular/cylindrical cut, step or cavity in the surface of strut 30 in front of probe 20 (in an upwind direction). such that airflow approaching probe 20 becomes more turbulent prior to reaching the probe. In a more particular embodiment, notch 34 is formed ahead of probe 20 in curved forward upper surface 32 of the strut adjacent to a point of extension of the probe from the strut. However, notch 34 need not be used in conjunction with curved forward upper surface 32 in all embodiments. Instead, either of these features can be used separately from the other. Notch 34 creates a swirling turbulent wake that impinges on probe 20, increasing the heat transfer and lowering the overall temperature of the probe. Flow separation from the corners on the strut also increases the turbulence. While a circular or cylindrical notch is used in exemplary embodiments of the present invention, other types of notches can be used to increase the turbulence in the airflow impinging on probe 20. For example, notch shapes such as v-shaped notches, rectangular-shaped notches, etc., can be positioned ahead of probe 20 on strut 30 in order to increase the turbulence in the airflow impinging upon probe 20. As fluid flow accelerates around a sharp corner, it separates from the surface, decreasing the local static temperature at the corner, and thus potentially increasing the local liquid water content at that point through the process of recirculation. It has been observed in wind tunnel testing that ice accretes first at the edges of square corners, such as the flat tip of an ice detector strut. A third aspect of the present invention is based in part upon the recognition that this effect can be used to accrete ice on probe 20 at a higher temperature than would otherwise be possible. As such, generally cylindrical probe 20 includes a flat tip 40 at its distal end providing generally square corners 42 at the intersection of the flat tip and. the remaining surfaces of the cylinder, which are in some embodiments substantially orthogonally oriented. The flat tip probe 20 accretes ice at higher temperatures as compared to more conventional hemispherical tipped probes. In testing, accretion of ice on the tip of probe 20 has been found to have the most significant effect on the vibrating probe frequency. It is has also been found that inclining the probe increases the critical temperature to some extent. In ice detector 14, strut 30 is inclined such that it forms an angle Φ relative to an axis 70 which is perpendicular to mounting flange 42. Probe 20 is shown as being inclined relative to axis 72 by an angle θ. In some embodiments, axes 70 and 72 are parallel (i.e., both perpendicular to flange 42), and angles Φ and θ are substantially equal, but this need not be the case. As an example, angles Φ and θ range between 0° and 30° in one embodiment. However, the present invention is not limited to any specific ranges of these angles. In the exemplary embodiment of ice detector 14 illustrated in FIGS. 2-1 through 2-3, the curved forward upper surface of strut 30, the circular notch 34 formed in strut 30, the flat tipped probe 20, and the probe inclination are used in combination to significantly increase the critical temperature of the probe. For example, the critical temperature of the probe was seen to increase by between 0.5° C. and more than 1° C., depending upon airspeed. These results were verified using icing wind tunnel testing. Referring now to FIG. 3, shown is a plot illustrating critical temperature improvements as a function of airspeed using ice detectors of the present invention. The plot shows the critical temperature difference between prototype ice detectors of the present invention relative to a standard ice detector tested at the same time. The critical temperature difference of an operating prototype ice detector (with electronics) as shown in FIGS. 2-1 through 2-3 is represented by the square symbols in FIG. 3. The data for the operating prototype was recorded from the frequency output of the detector. The diamond symbols in FIG. 3 correspond to the critical temperature of a non-operating prototype (no electronics) ice detector of the present invention, where the data is based upon when ice was visually seen to form on the probe. The critical temperature difference results shown in FIG. 3 are based upon wind tunnel test data. In the wind tunnel testing used to obtain the data illustrated in FIG. 3, for various airspeeds the temperature was raised until ice no longer formed.on the ice detector probe, and this temperature at which ice no longer formed was recorded. Then, the temperature was lowered until ice again formed on the ice detector probe, and this temperature at which ice again formed was recorded. FIG. 3 illustrates a trend of improved (increased) critical temperatures as a second order function of airspeed for the ice detectors of the present invention. Referring now to FIG. 4, shown is a plot of critical static temperature as a function of airspeed for both a standard prior art ice detector (represented by circular symbols) and for an ice detector as shown in FIGS. 2-1 through 2-3 (represented by square symbols). Consistent with the results shown in FIG. 3, the plot of FIG. 4 illustrates that, as airspeed increases, the critical temperature of the ice detector of the present invention decreases at a slower rate than does the critical temperature of the prior art ice detector. Thus, the relative improvement of the ice detector of the present invention over the prior art ice detector increases as a function of airspeed. Referring now to FIGS. 5-1 and 5-2, shown is probe 200-1 which is an alternate or more particular embodiment of probe 20 described above. As discussed, the present invention utilizes the fact that surface roughness and disturbances cause the boundary layer of a fluid near a surface to become turbulent or separate, changing the heat transfer from the surface. Probe 200-1 is configured to further utilize this phenomenon. Probe 200-1 includes a bump, ridge or other protruding surface roughness feature 205 on a surface of the cylinder. The feature 205 is located in some embodiments between 40° and 80° on either side of the centerline of the probe. The centerline of the probe is indicated in FIG. 5-1 by the airflow direction arrow 60. As can be seen in the static temperature contours of FIG. 5-2, static temperature is lowered near feature 205. This is due to the flow separation at the boundary layer caused by feature 205. Asymmetric flow lowers static temperature opposite the feature 205 relative to a standard cylindrical probe. A cold spot also develops where the boundary layer reattaches after the feature, and ice tends to accrete there due to runback and impingement influenced by the flow separation. The bump or feature itself collects ice more efficiently than the cylinder, starting a nucleation site that ices sooner. Another alternative probe 200-2 is shown in FIGS. 6-1 and 6-2. Probe 200-2 includes a surface roughness feature 210 in the form of a slot formed into the cylindrical probe body, instead of in the form of a protrusion from the probe body as was used in probe 200-1. Again, as seen in the static temperature contours of FIG. 6-2, the static temperature of the probe decreases in the vicinity of feature 210. FIGS. 7-1 and 7-2 illustrate similar improvements in a probe 200-3 having a pair of surface roughness features 210-1 and 210-2 in the form of slots formed asymmetrically into the cylindrical probe body relative to the centerline. FIGS. 8-1 and 8-2 illustrate an embodiment in which probe 200-4 includes multiple dimples 215 (dimples 215-1 through 215-6 are shown) formed in the probe body. In this embodiment, the dimples are arranged symmetrically relative to the centerline of the probe represented by airflow direction arrow 60. Dimples 215 can alternatively be slots similar to those shown in probes 200-2 and 200-3, or they can be longitudinally extending like slots 210, but of a lesser length. Symmetrical arrangement of surface roughness features may be necessary in some embodiments to balance vibrational modes of the probe. In yet other embodiments of the invention, the probes are modified with various other surface roughness features in order to cause turbulence and flow separation to cool the probe. For example FIG. 9-1 illustrates probe 200-5 including surface roughness features 220 formed in a crosshatch pattern on the probe body. Surface roughness features 220 can be machine tooled into the probe, or formed by other processes. In another example embodiment, probe 200-6 shown in FIG. 9-2 includes surface roughness features 230 in the form of circumferentially arranged ridges formed perpendicular to the longitudinal axis of the probe. These ridges can act as cooling fins for cooling the probe. Once again, these surface roughness features can be formed using machine tooling techniques or other processes. In yet another embodiment illustrated in FIG. 9-3, probe 200-7 includes surface roughness features 240 in the form of rows or columns of dimples or holes. In a still further embodiment illustrated in FIG. 9-4, probe 200-8 includes surface roughness features 250 in the form of holes or apertures formed in the probe body. The surface roughness features 250 can be arranged either symmetrically or asymmetrically on the probe. In some embodiments, the holes or apertures that form features 250 are open to an interior passageway 260 within probe 200-8. A vacuum source 270 or other mechanism for achieving a lower pressure within passageway 260 than exists outside of probe 200-8 can then be utilized to apply suction through the holes or apertures forming features 250. In these embodiments, the suction can be used to keep the boundary layer of air attached and laminar to the probe where desired, while boundary layer separation can be achieved elsewhere on the probe using other surface roughness features. As discussed above with reference to FIGS. 2-1 through 2-3, modification of the tip of probe 20 from a conventional hemispherical shape to a flat tip with sharp corners improves ice accretion on the probe tip. The sharp corners accelerate the fluid flow at the corner as the fluid flow separates, decreasing the local static temperature at the edge, and perhaps increasing the local liquid water content at that point. While the flat tip probe configuration has been found to be particularly useful in promoting ice accretion, other non-hemispherical tip configurations providing sharp edges or transitions can also be used in accordance with embodiments of the invention. Also, sharp edges can be formed elsewhere on the probe body, but it has been found that the tip of a vibrating probe is most sensitive to ice accretion. FIGS. 10-1 through 10-5 each illustrate an end and side view of different probe configurations having sharp edges or transitions at the distal tip. These configurations or features can also be considered surface roughness features since they depart from conventional cylindrical, hemispherically tipped probes having substantially smooth and continuous surfaces. However, these features largely take advantage of a different phenomenon than the surface roughness features described above. In each of these configurations, the sharp edges accrete ice at a higher ambient temperature than would be possible under identical conditions with a conventional hemispherical tipped probe. FIG. 10-1 illustrates probe 20 from FIG. 2-1 through 2-3 having flat tip 40 producing sharp edges 42. Shown in FIG. 10-2 is a probe 300-1 which is an alternate or more particular embodiment of probe 20 described above. Probe 300-1 includes first and second longitudinally extending probe sections 305 and 310 that form a sharp edge in the form of a step 315 between the two probe sections. In one embodiment, step 315 is made by forming probe section 310 to be smaller than probe section 305. For example, each of probe sections 305 and 310 can be half of conventional cylindrical shaped probes with hemispherical shaped tips, but with probe section 310 being shorter and/or of a smaller. radius than probe section 305. Other forms of steps can also be used. Further, the probe sections can be formed from different materials having differing thermal conductivities, but it is not necessary that the probe sections be formed from different materials. Shown in FIG. 10-3 is a probe 300-2 which is an alternate or more particular embodiment of probe 20 described above. Probe 300-2 includes a probe main body 325 and a probe extension or nipple 330 extending from the top or distal end of the probe main body. Probe extension 330 has, in this example embodiment, a flat tip surface 331 and one or more side surfaces 332 that form a sharp corner 333 at their intersections. In the illustrated embodiment, probe extension 330 is a cylindrical probe extension from a conventional. cylindrical shaped probe main body 325 having a hemispherical shaped tip. Shown in FIGS. 10-4 and 10-5 is a probe 300-3 that is another alternative or more particular embodiment of probe 20. Probe 300-3 includes a probe main body 350 and a ridge member 355. From an end view of probe 300-3, ridge member 355 extends longitudinally from the top of probe main body 350 in a direction that is approximately perpendicular to the longitudinal axis of probe main body 350. Ridge member 355 can be of a variety of different shapes, and need not actually extend along a longitudinal axis. FIG. 10-4 illustrates the probe with the ridge member 355 oriented orthogonal to the direction of airflow such that it forms a cross flow ridge. FIG. 10-5 illustrates the probe with the ridge member 355 oriented parallel to the direction of airflow such that it forms an in-line flow ridge. In either orientation, ridge member 355 provides sharp corners 356 that function as described with reference to other embodiments to accrete ice. In the illustrated embodiment, probe main body 350 is similar to a conventional cylindrical shaped probe having a hemispherical shaped tip. In the illustrated embodiment, ridge member 355 can be formed in an arcuate or semi-circular shape as shown in FIG. 10-5. However, other shapes can be used to provide the ridge member. For example, in alternate embodiments, ridge member 355 can be of a rectangular prism shape, and portions of probe main body 350 can be removed to allow ridge member 355 to extend laterally through the probe main body. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to vibrating type ice detectors for use with aircraft and in any other locations where the detection of ice is of importance. More particularly, the present invention relates to ice detector configurations that increase the critical temperature limit of an ice detector probe to provide earlier ice detection. Existing ice detectors are useful in near freezing temperature conditions for detecting the formation of ice on the detector, and providing a warning of the ice formation prior to the formation of ice on the wings, engine nacelles, and other control surfaces of an aircraft. A frequently used type of ice detector is a vibrating ice detector. Vibrating type ice detectors use a vibrating probe upon which ice accumulates. Typically, the probe is a cylindrical probe having a hemispherical end. Examples of vibrating type ice detectors are described, for example, in U.S. Pat. Nos. 3,341,835 entitled ICE DETECTOR by F. D. Werner et al.; 4,553,137 entitled NON-INSTRUSIVE ICE DETECTOR by Marxer et al.; 4,611,492 entitled MEMBRANE TYPE NON-INTRUSIVE DETECTOR by Koosmann; 6,269,320 entitled SUPERCOOLED LARGE DROPLET ICE DETECTOR by Otto; and 6,320,511 entitled ICE DETECTOR CONFIGURATION FOR IMPROVED ICE DETECTION AT NEAR FREEZING CONDITIONS by Cronin et al., which are herein incorporated by reference in their entirety. The ability of ice detectors to provide a warning of ice formation prior to formation of ice on the wings, engine nacelles, or other control surface of an aircraft is dependent upon the critical temperature of the ice detector probe and the critical temperature of the aircraft wings or control surface. The critical temperature is defined as the ambient static temperature at or above which none of the supercooled liquid water droplets in a cloud will freeze when they impinge on a structure. Stated another way, the critical temperature is the temperature above which no ice will form (or below which ice will form) on a structure (such as an aircraft wing or an ice detector probe) given its configuration and other atmospheric conditions. The critical temperature can be different for different structures, and specifically for a typical airfoil configuration and for a conventional ice detector, at the same airspeed. Since the critical temperature of an ice detector probe is the temperature below which ice will begin to form on the probe, thus defining the upper temperature limit at which the ice detector will not detect icing conditions, it is of significant interest in the design of ice detectors. Ensuring that the critical temperature of the ice detector probe is above the critical temperature of the wings or other control surfaces of an aircraft is a continuing challenge, particularly with newer airfoil designs. Therefore, a vibrating type ice detector having a probe with an increased critical temperature would be a significant improvement in the art. Other ice accretion improving features would similarly be significant improvements in the ice detector art. The present invention addresses one or more of the above-identified problems and/or provides other advantages over prior art ice detectors. | <SOH> SUMMARY OF THE INVENTION <EOH>An ice detector for providing a signal indicating ice formation includes a probe protruding into an airflow. The probe extends into the airflow from a strut. The strut has one or more features which allow the probe to accrete ice at a higher temperature than would conventionally be possible. Also, the probe can include surface roughness features that further improve ice detection. Surface roughness features on the probe include ice accreting edges at a distal end of the probe and features arranged on a side surface of the probe which cause the airflow to increase in turbulence, thereby decreasing the temperature of the probe. Decreasing the temperature of the probe, along with increasing the critical temperature of the probe, improves ice accretion on the probe, and thereby ice detection. | 20040331 | 20060912 | 20051006 | 98158.0 | 0 | DINH, TIEN QUANG | ICE DETECTOR FOR IMPROVED ICE DETECTION AT NEAR FREEZING CONDITION | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,814,971 | ACCEPTED | Stabilized polycarbonate polyester composition | A stabilized thermoplastic resin composition is disclosed which comprises structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester and a combination of at least two quenchers, wherein said quencher is selected from a group consisting of phosphorus compound, carboxylic acid, derivates of carboxylic acids, epoxy functional polymers and boron compound. Also disclosed is a stabilized thermoplastic resin composition comprising: structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester, an epoxy functional polymers and a combination of at least one quenchers, wherein said quencher is selected from a group consisting of phosphorus compounds, carboxylic acid compounds, polyols, and boron compounds. In addition the composition disclosed possess good optical properties, thermal properties and stability. | 1. A stabilized thermoplastic resin composition comprising: structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester and a combination of at least two quenchers, wherein said quencher is selected from a group consisting of phosphorus compounds, carboxylic acid compounds, epoxy functioned polymers, polyols, and boron compounds. 2. The composition of claim 1, wherein said polycarbonate comprises repeating units of the formula: wherein R1 is a divalent aromatic radical derived from a dihydroxyaromatic compound of the formula HO-D-OH, wherein D has the structure of formula: wherein A1 represents an aromatic group; E comprises a sulfur-containing linkage, sulfide, sulfoxide, sulfone; a phosphorus-containing linkage, phosphinyl, phosphonyl; an ether linkage; a carbonyl group; a tertiary nitrogen group; a silicon-containing linkage; silane; siloxy; a cycloaliphatic group; cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, methylcyclohexylidene, 2-[2.2.1]-bicycloheptylidene, neopentylidene, cyclopentadecylidene, cyclododecylidene, adamantylidene; an alkylene or alkylidene group, which group may optionally be part of one or more fused rings attached to one or more aromatic groups bearing one hydroxy substituent; an unsaturated alkylidene group; or two or more alkylene or alkylidene groups connected by a moiety different from alkylene or alkylidene and selected from the group consisting of an aromatic linkage, a tertiary nitrogen linkage; an ether linkage; a carbonyl linkage; a silicon-containing linkage, silane, siloxy; a sulfur-containing linkage, sulfide, sulfoxide, sulfone; a phosphorus-containing linkage, phosphinyl, and phosphonyl; R1 independently at each occurrence comprises a mono-valent hydrocarbon group, alkenyl, allyl, alkyl, aryl, aralkyl, alkaryl, or cycloalkyl; Y1 independently at each occurrence is selected from the group consisting of an inorganic atom, a halogen; an inorganic group, a nitro group; an organic group, a monovalent hydrocarbon group, alkenyl, allyl, alkyl, aryl, aralkyl, alkaryl, cycloalkyl, and an alkoxy group; the letter “m” represents any integer from and including zero through the number of replaceable hydrogens on A1 available for substitution; the letter “p” represents an integer from and including zero through the number of replaceable hydrogens on E available for substitution; the letter “t” represents an integer equal to at least one; the letter “s” represents an integer equal to either zero or one; and “u” represents any integer including zero. 3. The composition of claim 2, wherein the dihydroxyaromatic compound from which D is derived is bisphenol A. 4. The composition of claim 1, wherein the polyester is derived from structural units comprising at least one substituted or unsubstituted aliphatic diols, or substituted or unsubstituted cycloaliphatic diol and at least one substituted or unsubstituted aromatic dicarboxylic acid or substituted or unsubstituted aliphatic dicarboxylic acid. 5. The composition of claim 1, wherein said polyester is at least one selected form a group consisting of poly(alkylene phthalate)s, poly(cycloalkylene phthalate)s, poly(alkylene dicarboxylate)s, polyesteramide copolymers, copolyesters derived from structural units comprising at least one alkyl diol, or cycloaliphatic diols, and at least one aromatic acids, aliphatic acids and cycloaliphatic acids. 6. The composition of claim 1, wherein said polyester is at least one selected from a group consisting of poly(ethylene terephthalate), poly(butylene terephthalate), poly(propylene terephthalate), poly(cyclohexanedimethanol terephthalate), poly(cyclohexanedimethanol-terephthalic acid-ethylene glycol), poly(butylene-2,6-napthalate), poly(ethylene-2,6-naphthalate), poly(butylene dicarboxylate) and combinations thereof. 7. The composition of claim 1, wherein said thermoplastic resin composition comprises structural units derived from polyester and polycarbonate in a range of about 90 to 10 percent by weight of polyester and 10 to 90 percent by weight of polycarbonate. 8. The composition of claim 1, wherein said thermoplastic resin composition comprises structural units derived from polyester and polycarbonate in a range of about 75 to 25 percent by weight of polyester and 25 to 75 percent by weight of polycarbonate. 9. The composition of claim 1, wherein said phosphorus compound is at least one selected from the group consisting of oxo acids, organo phosphates, acid phosphate metal salts, acid organo phosphites, diphosphites, esters of phosphoric acid, salts of phosphoric acids arylphosphonic acid, metal salts of phosphites. 10. The composition of claim 9, wherein said phosphorus compound is at least one selected from the group consisting of phosphorus oxo acids, esters of phosphoric acid, salts of phosphoric acids and arylphosphonic acid. 11. The composition of claim 1, wherein said boron compound is boric acid. 12. The composition of claim 1, wherein said polyol is of the formula R16—(OH)r wherein, R16 is at least one selected from a group consisting of substituted or unsubstituted aliphatic moiety, a substituted or unsubstituted aliphatic-aromatic moiety having from 2 to 20 carbon atoms and r is a positive integer having a value of from 2 up to the number of replaceable hydrogen atoms present on R5. 13. The composition of claim 12, wherein said polyol is an acyclic aliphatic polyhydric alkanol. 14. The composition of claim 12, wherein said polyol is hexahydric alcohol. 15. The composition of claim 12, wherein said polyol is at least one selected form the group consisting of mannitol, butanediol, cyclohexane dimethanol, 1,3-propanediol glycerol, 1,2-pentanediol, 1,3,5-cyclohexanetriol, sorbitol, inositol and combinations thereof. 16. The composition of claim 1, wherein said carboxylic acid is of the formula wherein X1 is 0 or NH; X2 is OR18 when X1 is NH and X2 is OR18 or NHR18 when X1 is 0; Z is CH or a substituted or unsubstituted aromatic carbocyclic radical; R17 is hydrogen or a substituted or unsubstituted hydrocarbon-based radical; R18 is selected from a group consisting of hydrogen, alkyl, aryl, radicals having up to 10 carbon atoms. 17. The composition of claim 16, wherein said carboxylic acid derivative is at least one selected from a group consisting of alkyl salicylate, aryl salicylate, salicylamide, glycine, mailc acid, mandelic acid, dibutyl tartrate and combinations thereof. 18. The composition of claim 1, wherein said epoxy functional polymers comprise of at least one epoxy-functional alkyl acrylic monomer and at least one functional or non-functional styrenic and/or alkyl acrylic monomer. 19. The composition of claim 18, wherein said epoxy functional polymers is an epoxy-functional styrene (meth)acrylic copolymers comprises at least one epoxy functional (meth)acrylic monomer and at least one non-functional styrenic and/or (meth)acrylic monomer. 20. The composition of claim 1, wherein said thermoplastic resin composition has a yellowness index of less than about 10. 21. The composition of claim 1, wherein said optically clear resin composition transmits about greater than 85 percent light in the region of about 250 nm to about 300 nm. 22. The composition of claim 1, wherein said optically clear resin composition has a haze value about less than 15. 23. The composition of claim 1, wherein said composition may optionally comprise additional components, said additional components is selected from a group consisting of anti-oxidants, flame retardants, reinforcing materials, colorants, mold release agents, fillers, nucleating agents, UV light stabilizers, heat stabilizers, lubricants, and combinations thereof. 24. An article comprising the composition of claim 1. 25. A process to prepare a stabilized thermoplastic resin composition comprising: structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester and a combination of at least two quenchers, wherein said quencher is selected from a group consisting of phosphorus compound, carboxylic acid, derivates of carboxylic acids, epoxy functioned polymers and boron compound wherein said process comprises the steps of: a. melting said polycarbonate and polyester to form a molten mixture; b. extruding said molten mixture in an extruder to form an extrudate; and c. molding said extrudate. 26. The process according to claim 25, further comprising the step of pelletizing the extrudate. 27. The process according to claim 25, wherein said melting is carried out at in temperature range between about 225° C. and about 300° C. 28. The process according to claim 25, wherein said extruding is carried out at a temperature range between about 200° C. and about 250° C. 29. The process according to claim 25, wherein said melting may optionally be carried out in presence of a catalyst. 30. The process according to claim 25, wherein said catalyst is at least one selected from the group consisting of alkali metal and alkaline earth metal salts of aromatic dicarboxylic acids, alkali metal and alkaline earth metal salts of aliphatic dicarboxylic acids, Lewis acids, metal oxides, their coordination complexes and mixtures thereof. 31. A stabilized thermoplastic resin composition comprising: structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester, an epoxy functional polymers and a combination of at least one quenchers, wherein said quencher is selected from a group consisting of phosphorus compounds, carboxylic acid compounds, polyols, and boron compounds. 32. The composition of claim 31, wherein said epoxy functional polymers comprise of at least one epoxy-functional alkyl acrylic monomer and at least one functional or non-functional styrenic and/or alkyl acrylic monomer. 33. The composition of claim 31, wherein said epoxy functional polymers is an epoxy-functional styrene (meth)acrylic copolymers comprises at least one epoxy functional (meth)acrylic monomer and at least one non-functional styrenic and/or (meth)acrylic monomer. 34. An article made from the composition of claim 31. | CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application Ser. No. 60/524148 filed on Nov. 21, 2003, which is incorporated herein by reference in its entirety BACKGROUND OF THE INVENTION This invention relates to a stabilized thermoplastic resin composition, a method to synthesize the composition and articles made from the compositions. Polycarbonate is a useful engineering plastic for parts requiring clarity, high toughness, and, in some cases, good heat resistance. However, polycarbonate also has some important deficiencies, among them poor chemical and stress crack resistance, poor resistance to sterilization by gamma radiation, and poor processability. Blends of polyesters with polycarbonates provide thermoplastic compositions having improved properties over those based upon either of the single resins alone. Moreover, such blends are often more cost effective than polycarbonate alone. The miscibility of PC with the polyesters gives the blends the clarity needed, but this is restricted to (semi)aliphatic polyesters such as poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) or a glycolized copolyester such as polyethylene glycol cyclohexane dimethanol terephthalate (PCTG). PCT patent application no. WO 02/38675 discloses a thermoplastic composition comprising PC, PCCD, and an impact modifier. U.S. Pat. No. 4,188,314, U.S. Pat. No. 4,125,572; U.S. Pat. No. 4,391,954; U.S. Pat. No. 4,786,692; U.S. Pat. Nos. 4,897,453, and 5,478,896 relate to blends of an aromatic polycarbonate and poly cyclohexane dimethanol phthalate. U.S. Pat. No. 4,125,572 relates to a blend of polycarbonate, polybutylene terephthalate (PBT) and an aliphatic/cycloaliphatic iso/terephthalate resin. U.S. Pat. No. 6,281,299 discloses a process for manufacturing transparent polyester/polycarbonate compositions, wherein the polyester is fed into the reactor after bisphenol A is polymerized to a polycarbonate. Moldable crystalline resin compositions such as polycarbonate-polyester blends are desirable for many applications. On exposure to high temperature and humidity, such blends may exhibit relatively poor hydrolytic stability. Another problem associated with these blends is due to ester-carbonate interchange, also known as trans esterification, which may lead to loss of mechanical properties. Catalyst quenchers are typically used to prevent such interchange reactions. However these catalyst quenchers can also promote degradation of polymer chains and contribute to decrease in hydrolytic stability. Conventionally phosphorus derivatives such as phosphoric acid, phosphates have been used as quenchers. U.S. Pat. Nos. 4,532,290, 4,555,540, 4,401,804, U.S. Pat. No. 20,030,032,725, describes the phosphorous-containing compounds include phosphoric acid, certain organic phosphorous compounds such as distearyl pentaerythritol diphosphate, mono or dihydogen phosphate are useful in deactivating metallic catalyst residues. The use of phosphite stabilizers is not satisfactory because of the tendency to be unstable to both hydrolysis and oxidation. U.S. Pat. No. 4,452,933 teaches the use of hydroxy or amino substituted carboxylic acid derivatives such as Methyl salicylate, Malic acid, Glycine or dibutyl tartrate to effectively inhibit ester-carbonate interchange reaction. The U.S. Pat. No. 4,560,722 discloses a stabilized polycarbonate polyester blend with boric acid as a stabilizer. EP Patent 02 72417 teaches the use of polyols as a color stabilizer stabilizing the polycarbonate polyester composition. U.S. Pat. No. 5,087,665 Chung et al. disclose a method of improving the hydrolytic stability of blends of polycarbonate and polyethylene terephthalate, by adding polyethylene to the blends. U.S. Pat. Nos. 5,411,999 and 5,596,049 describe the use of epoxy based material in conjugation with the catalyst quenchers to promote hydrolytic stability. However, a disadvantage is that the epoxy compounds were used in combination with metal catalyst, such as sodium stearate, which in turn may result in loss in polycarbonate molecular weight. U.S. Pat. No. 4,760,107 teaches a addition of a combination of an epoxide with polyols to polycarbonate polyester blends for color retention properties. European Patent Nos. EP 0 273149 and EP 0 497 818, describe additions of epoxy oligomeric materials to certain polyesters, disclose thermal stability in glass reinforced and/or flame-retarded polyester formulations. U.S. Pat. 5,300,546 relates to polyester compositions with mineral fillers giving a ceramic feel which have improved hydrolytic stability and melt viscosity stability. There is a continuing need for polycarbonate polyester blends having a good balance of optical property, processability, solvent resistance and hydrostability in addition to good mechanical and thermal properties. BRIEF DESCRIPTION OF THE INVENTION The present inventors have unexpectedly discovered a thermoplastic resin composition comprising structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester and a combination of at least two quenchers, wherein said quencher is selected from a group consisting of phosphorus compound, carboxylic acid, derivates of carboxylic acids, epoxy functional polymers and boron compound. Also disclosed is a synthesis method for the optically clear thermoplastic resin compositions of the present invention and articles derived from said composition. In an embodiment of the present invention discloses a stabilized thermoplastic resin composition comprising: structural units derived from at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester, an epoxy functional polymers and a combination of at least one quenchers, wherein said quencher is selected from a group consisting of phosphorus compounds, carboxylic acid compounds, polyols, and boron compounds. In another embodiment of the present invention the stabilized composition of the present invention has improved properties. Various other features, aspects, and advantages of the present invention will become more apparent with reference to the following description, examples, and appended claims. DETAILED DESCRIPTION OF THE INVENTION The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included herein. In this specification and in the claims, which follow, reference will be made to a number of terms which shall be defined to have the following meanings. The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. As used herein the term “polycarbonate” refers to polycarbonates incorporating structural units derived from one or more dihydroxy aromatic compounds and includes copolycarbonates and polyester. As used herein the term “PCCD” is defined as poly(cyclohexane-1,4-dimethylene cyclohexane-1,4-dicarboxylate). A component of the blend of the invention is an aromatic polycarbonate. The aromatic polycarbonate resins suitable for use in the present invention, methods of making polycarbonate resins and the use of polycarbonate resins in thermoplastic molding compounds are well-known in the art, see,.generally, U.S. Pat. Nos. 3,169,121, 4,487,896 and 5,411,999, the respective disclosures of which are each incorporated herein by reference. Polycarbonates useful in the invention comprise repeating units of the formula (I) wherein R1 is a divalent aromatic radical derived from a dihydroxyaromatic compound of the formula HO-D-OH, wherein D has the structure of formula: wherein A1 represents an aromatic group including, but not limited to, phenylene, biphenylene, naphthylene, and the like. In some embodiments E may be an alkylene or alkylidene group including, but not limited to, methylene, ethylene, ethylidene, propylene, propylidene, isopropylidene, butylene, butylidene, isobutylidene, amylene, amylidene, isoamylidene, and the like. In other embodiments when E is an alkylene or alkylidene group, it may also consist of two or more alkylene or alkylidene groups connected by a moiety different from alkylene or alkylidene, including, but not limited to, an aromatic linkage; a tertiary nitrogen linkage; an ether linkage; a carbonyl linkage; a silicon-containing linkage, silane, siloxy; or a sulfur-containing linkage including, but not limited to, sulfide, sulfoxide, sulfone, and the like; or a phosphorus-containing linkage including, but not limited to, phosphinyl, phosphonyl, and the like. In other embodiments E may be a cycloaliphatic group including, but not limited to, cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, methylcyclohexylidene, 2-[2.2.1]-bicycloheptylidene, neopentylidene, cyclopentadecylidene, cyclododecylidene, adamantylidene, and the like; a sulfur-containing linkage, including, but not limited to, sulfide, sulfoxide or sulfone; a phosphorus-containing linkage, including, but not limited to, phosphinyl or phosphonyl; an ether linkage; a carbonyl group; a tertiary nitrogen group; or a silicon-containing linkage including, but not limited to, silane or siloxy. R1 independently at each occurrence comprises a monovalent hydrocarbon group including, but not limited to, alkenyl, allyl, alkyl, aryl, aralkyl, alkaryl, or cycloalkyl. In various embodiments a monovalent hydrocarbon group of R1 may be halogen-substituted, particularly fluoro- or chloro-substituted, for example as in dichloroalkylidene, particularly gem-dichloroalkylidene. Y1 independently at each occurrence may be an inorganic atom including, but not limited to, halogen (fluorine, bromine, chlorine, iodine); an inorganic group containing more than one inorganic atom including, but not limited to, nitro; an organic group including, but not limited to, a monovalent hydrocarbon group including, but not limited to, alkenyl, allyl, alkyl, aryl, aralkyl, alkaryl, or cycloalkyl, or an oxy group including, but not limited to, OR2 wherein R2 is a monovalent hydrocarbon group including, but not limited to, alkyl, aryl, aralkyl, alkaryl, or cycloalkyl; it being only necessary that Y1 be inert to and unaffected by the reactants and reaction conditions used to prepare the polymer. In some particular embodiments Y1 comprises a halo group or C1-C6 alkyl group. The letter “m” represents any integer from and including zero through the number of replaceable hydrogens on A1 available for substitution; “p” represents an integer from and including zero through the number of replaceable hydrogens on E available for substitution; “t” represents an integer equal to at least one; “s” represents an integer equal to either zero or one; and “u” represents any integer including zero. In dihydroxy-substituted aromatic hydrocarbons in which D is represented by formula (II) above, when more than one Y1 substituent is present, they may be the same or different. The same holds true for the R1 substituent. Where “s” is zero in formula (II) and “u” is not zero, the aromatic rings are directly joined by a covalent bond with no intervening alkylidene or other bridge. The positions of the hydroxyl groups and Y1 on the aromatic nuclear residues A1 can be varied in the ortho, meta, or para positions and the groupings can be in vicinal, asymmetrical or symmetrical relationship, where two or more ring carbon atoms of the hydrocarbon residue are substituted with Y1 and hydroxyl groups. In some particular embodiments the parameters “t”, “s”, and “u” each have the value of one; both A1 radicals are unsubstituted phenylene radicals; and E is an alkylidene group such as isopropylidene. In some particular embodiments both A1 radicals are p-phenylene, although both may be o- or m-phenylene or one o- or m-phenylene and the other p-phenylene. In some embodiments of dihydroxy-substituted aromatic hydrocarbons E may be an unsaturated alkylidene group. Suitable dihydroxy-substituted aromatic hydrocarbons of this type include those of the formula (III): where independently each R4 is hydrogen, chlorine, bromine or a C1-30 monovalent hydrocarbon or hydrocarbonoxy group, each Z is hydrogen, chlorine or bromine, subject to the provision that at least one Z is chlorine or bromine. Suitable dihydroxy-substituted aromatic hydrocarbons also include those of the formula (IV): where independently each R4 is as defined hereinbefore, and independently Rg and Rh are hydrogen or a C1-30 hydrocarbon group. In some embodiments of the present invention, dihydroxy-substituted aromatic hydrocarbons that may be used comprise those disclosed by name or formula (generic or specific) in U.S. Pat. Nos. 2,991,273, 2,999,835, 3,028,365, 3,148,172, 3,153,008, 3,271,367, 3,271,368, and 4,217,438. In other embodiments of the invention, dihydroxy-substituted aromatic hydrocarbons comprise bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, 1,4-dihydroxybenzene, 4,4′-oxydiphenol, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 4,4′-(3,3,5-trimethylcyclohexylidene)diphenol; 4,4′-bis(3,5-dimethyl)diphenol, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane; 4,4-bis(4-hydroxyphenyl)heptane; 2,4′-dihydroxydipenylmethane; bis(2-hydroxyphenyl)methane; bis(4-hydrocyphenyl)methane; bis(4-hydroxy-5-nitrophenyl)methane; bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane; 1,2-bis(4-hydroxyphenyl)ethane; 1,1-bis(4-hydroxy-2-chlorophenyl)ethane; 2,2-bis(3-phenyl-4-hydroxyhenyl)propane; 2,2-bis(4-hydroxy-3-methylphenyl)propane; 2,2-bis(4-hydroxy-3-ethylphenyl)propane; 2,2-bis(4-hydroxy-3-isopropylphenyl)propane; 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane; 3,5,3′,5′-tetrachloro-4,4′-dihydroxyphenyl)propane; bis(4-hydroxyphenyl)cyclohexylmethane; 2,2-bis(4-hydroxyphenyl)-1-phenylpropane; 2,4′-dihydroxyphenyl sulfone; dihydroxy naphthalene; 2,6-dihydroxy naphthalene; hydroquinone; resorcinol; C1-3 alkyl-substituted resorcinols; methyl resorcinol, catechol, 1,4-dihydroxy-3-methylbenzene; 2,2-bis(4-hydroxyphenyl)butane; 2,2-bis(4-hydroxyphenyl)-2-methylbutane; 1,1-bis(4-hydroxyphenyl)cyclohexane; 4,4′-dihydroxydiphenyl; 2-(3-methyl-4-hydroxyphenyl-2-(4-hydroxyphenyl)propane; 2-(3,5-dimethyl-4-hydroxyphenyl)-2-(4-hydroxyphenyl)propane; 2-(3-methyl-4-hydroxyphenyl)-2-(3,5-dimethyl-4-hydroxyphenyl)propane; bis(3,5-dimethylphenyl-4-hydroxyphenyl)methane; 1,1-bis(3,5-dimethylphenyl-4-hydroxyphenyl)ethane; 2,2-bis(3,5-dimethylphenyl-4-hydroxyphenyl)propane; 2,4-bis(3,5-dimethylphenyl-4-hydroxyphenyl)-2-methylbutane; 3,3-bis(3,5-dimethylphenyl-4-hydroxyphenyl)pentane; 1,1-bis(3,5-dimethylphenyl-4-hydroxyphenyl)cyclopentane; 1,1-bis(3,5-dimethylphenyl-4-hydroxyphenyl)cyclohexane; bis(3,5-dimethyl-4-hydroxyphenyl) sulfoxide, bis(3,5-dimethyl-4-hydroxyphenyl) sulfone and bis(3,5-dimethylphenyl-4-hydroxyphenyl)sulfide. In a particular embodiment the dihydroxy-substituted aromatic hydrocarbon comprises bisphenol A. In some embodiments of dihydroxy-substituted aromatic hydrocarbons when E is an alkylene or alkylidene group, said group may be part of one or more fused rings attached to one or more aromatic groups bearing one hydroxy substituent. Suitable dihydroxy-substituted aromatic hydrocarbons of this type include those containing indane structural units such as represented by the formula (V), which compound is 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol, and by the formula (VI), which compound is 1-(4-hydroxyphenyl)-1,3,3-trimethylindan-5-ol: Also included among suitable dihydroxy-substituted aromatic hydrocarbons of the type comprising one or more alkylene or alkylidene groups as part of fused rings are the 2,2,2′,2′-tetrahydro-1,1′,spirobi[1H-indene]diols having formula (VII): wherein each R6 is independently selected from monovalent hydrocarbon radicals and halogen radicals; each R7, R8, R9, and R10 is independently C1-6 alkyl; each R11 and R12 is independently H or C1-6 alkyl; and each n is independently selected from positive integers having a value of from 0 to 3 inclusive. In a particular embodiment the 2,2,2′,2′-tetrahydro-1,1′-spirobi[1H-indene]diol is 2,2,2′,2′-tetrahydro-3,3,3′,3′-tetramethyl-1,1′-spirobi[1H-indene]-6,6′-diol (sometimes known as “SBI”). Mixtures of alkali metal salts derived from mixtures of any of the foregoing dihydroxy-substituted aromatic hydrocarbons may also be employed. The term “alkyl” as used in the various embodiments of the present invention is intended to designate both linear alkyl, branched alkyl, aralkyl, cycloalkyl, bicycloalkyl, tricycloalkyl and polycycloalkyl radicals containing carbon and hydrogen atoms, and optionally containing atoms in addition to carbon and hydrogen, for example atoms selected from Groups 15, 16 and 17 of the Periodic Table. The term “alkyl” also encompasses that alkyl portion of alkoxide groups. In various embodiments normal and branched alkyl radicals are those containing from 1 to about 32 carbon atoms, and include as illustrative non-limiting examples C1-C32 alkyl optionally substituted with one or more groups selected from C1-C32 alkyl, C3-C15 cycloalkyl or aryl; and C3-C15 cycloalkyl optionally substituted with one or more groups selected from C1-C32 alkyl. Some particular illustrative examples comprise methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tertiary-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl. Some illustrative non-limiting examples of cycloalkyl and bicycloalkyl radicals include cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, bicycloheptyl and adamantyl. In various embodiments aralkyl radicals are those containing from 7 to about 14 carbon atoms; these include, but are not limited to, benzyl, phenylbutyl, phenylpropyl, and phenylethyl. In various embodiments aryl radicals used in the various embodiments of the present invention are those substituted or unsubstituted aryl radicals containing from 6 to 18 ring carbon atoms. Some illustrative non-limiting examples of these aryl radicals include C6-C15 aryl optionally substituted with one or more groups selected from C1-C32 alkyl, C3-C15 cycloalkyl or aryl. Some particular illustrative examples of aryl radicals comprise substituted or unsubstituted phenyl, biphenyl, toluyl and naphthyl. Mixtures comprising two or more hydroxy-substituted hydrocarbons may also be employed. In some particular embodiments mixtures of at least two monohydroxy-substituted alkyl hydrocarbons, or mixtures of at least one monohydroxy-substituted alkyl hydrocarbon and at least one dihydroxy-substituted alkyl hydrocarbon, or mixtures of at least two dihydroxy-substituted alkyl hydrocarbons, or mixtures of at least two monohydroxy-substituted aromatic hydrocarbons, or mixtures of at least two dihydroxy-substituted aromatic hydrocarbons, or mixtures of at least one monohydroxy-substituted aromatic hydrocarbon and at least one dihydroxy-substituted aromatic hydrocarbon, or mixtures of at least one monohydroxy-substituted alkyl hydrocarbon and at least one dihydroxy-substituted aromatic hydrocarbon may be employed. In yet another, the polycarbonate resin is a linear polycarbonate resin that is derived from bisphenol A and phosgene. In an alternative embodiment, the polycarbonate resin is a blend of two or more polycarbonate resins. The aromatic polycarbonate may be prepared in the melt, in solution, or by interfacial polymerization techniques well known in the art. For example, the aromatic polycarbonates can be made by reacting bisphenol-A with phosgene, dibutyl carbonate or diphenyl carbonate. Such aromatic polycarbonates are also commercially available. In one embodiment, the aromatic polycarbonate resins are commercially available from General Electric Company, e.g., LEXAN™ bisphenol A-type polycarbonate resins. The preferred polycarbonates are preferably high molecular weight aromatic carbonate polymers have an intrinsic viscosity (as measured in methylene chloride at 25° C.) ranging from about 0.30 to about 1.00. deciliters per gram. Polycarbonates may be branched or unbranched and generally will have a weight average molecular weight of from about 10,000 to about 200,000, preferably from about 20,000 to about 100,000 as measured by gel permeation chromatography. It is contemplated that the polycarbonate may have various known end groups. In one embodiment the optically clear thermoplastic composition comprises polyesters. Methods for making polyester resins and the use of polyester resins in thermoplastic molding compositions are known in the art. Conventional polycondensation procedures are described in the following, see, generally, U.S. Pat. Nos. 2,465,319, 5,367,011 and 5,411,999, the respective disclosures of which are each incorporated herein by reference. Typically polyester resins include crystalline polyester resins such as polyester resins derived from an aliphatic or cycloaliphatic diol, or mixtures thereof, containing from 2 to about 10 carbon atoms and at least one aromatic dicarboxylic acid. Preferred polyesters are derived from an aliphatic-diol and an dicarboxylic acid and have repeating units according to structural formula (VIII) wherein, R′ is an alkyl radical compromising a dehydroxylated residue derived from an aliphatic or cycloaliphatic diol, or mixtures thereof, containing from 2 to about 20 carbon atoms. R is an aryl radical comprising a decarboxylated residue derived from an aromatic dicarboxylic acid. In one embodiment of the present invention the polyester could be an aliphatic polyester where at least one of R′ or R is a cycloalkyl containing radical. The polyester is a condensation product where R′ is the residue of an aryl, alkane or cycloalkane containing diol having 6 to 20 carbon atoms or chemical equivalent thereof, and R is the decarboxylated residue derived from an aryl, aliphatic or cycloalkane containing diacid of 6 to 20 carbon atoms or chemical equivalent thereof. The polyester resins are typically obtained through the condensation or ester interchange polymerization of the diol or diol equivalent component with the diacid or diacid chemical equivalent component. The diacids meant to include carboxylic acids having two carboxyl groups each useful in the preparation of the polyester resins of the present invention are preferably aliphatic, aromatic, cycloaliphatic. Examples of diacids are cyclo or bicyclo aliphatic acids, for example, decahydro naphthalene dicarboxylic acids, norbornene dicarboxylic acids, bicyclo octane dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid or chemical equivalents, and most preferred is trans-1,4-cyclohexanedicarboxylic acid or a chemical equivalent. Linear dicarboxylic acids like adipic acid, azelaic acid, dicarboxyl dodecanoic acid, and succinic acid may also be useful. Chemical equivalents of these diacids include esters, alkyl esters, e.g., dialkyl esters, diaryl esters, anhydrides, salts, acid chlorides, acid bromides, and the like. Examples of aromatic dicarboxylic acids from which the decarboxylated residue R may be derived are acids that contain a single aromatic ring per molecule such as, e.g., isophthalic or terephthalic acid, 1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether, 4,4′-bisbenzoic acid and mixtures thereof, as well as acids contain fused rings such as, e.g., 1,4- or 1,5-naphthalene dicarboxylic acids. In a preferred embodiment, the dicarboxylic acid precursor of residue R is terephthalic acid or, alternatively, a mixture of terephthalic and isophthalic acids. Some of the diols useful in the preparation of the polyester resins of the present invention are straight chain, branched, or cycloaliphatic alkane diols and may contain from 2 to 12 carbon atoms. Examples of such diols include but are not limited to ethylene glycol; propylene glycol, i.e., 1,2- and 1,3-propylene glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl, 1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol; 2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin, dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularly its cis- and trans-isomers; triethylene glycol; 1,10-decane diol; and mixtures of any of the foregoing. Preferably, a cycloaliphatic diol or chemical equivalent thereof and particularly 1,4-cyclohexane dimethanol or its chemical equivalents are used as the diol component. Chemical equivalents to the diols include esters, such as dialkylesters, diaryl esters, and the like. Typically the polyester resin may comprise one or more resins selected from linear polyester resins, branched polyester resins and copolymeric polyester resins. Suitable linear polyester resins include, e.g., poly(alkylene phthalate)s such as, e.g, poly(ethylene terephthalate) (“PET”), poly(butylene terephthalate) (“PBT”), poly(propylene terephthalate) (“PPT”), poly(cycloalkylene phthalate)s such as, e.g., poly(cyclohexanedimethanol terephthalate) (“PCT”), poly(alkylene naphthalate)s such as, e.g., poly(butylene-2,6-naphthalate) (“PBN”) and poly(ethylene-2,6-naphthalate) (“PEN”), poly(alkylene dicarboxylate)s such as, e.g., poly(butylene dicarboxylate). In a preferred embodiment suitable copolymeric polyester resins include, e.g., polyesteramide copolymers, cyclohexanedimethanol-terephthalic acid-isophthalic acid copolymers and cyclohexanedimethanol-terephthalic acid-ethylene glycol (“PCTG”) copolymers. The polyester component can, without limitation, comprise the reaction product of a glycol portion comprising 1,4-cyclohexanedimethanol and ethylene glycol, wherein the 1,4-cyclohexanedimethanol is greater than 50 mole percent based on the total moles of 1,4-cyclohexanedimethanol and ethylene glycol with an acid portion comprising terephthalic acid, or isophthalic acid or mixtures of both acids. The polyester component may be prepared by procedures well known to those skilled in this art, such as by condensation reactions. The condensation reaction may be facilitated by the use of a catalyst, with the choice of catalyst being determined by the nature of the reactants. The various catalysts for use herein are very well known in the art and are too numerous to mention individually herein. Generally, however, when an alkyl ester of the dicarboxylic acid compound is employed, an ester interchange type of catalyst is preferred, such as Ti(OC4H9)6 in n-butanol. In one embodiment copolyester in the subject invention is a copolyester as described above wherein the cyclohexanedimethanol portion has a predominance over ethylene glycol, preferably is about greater than 55 molar percent of cyclohexanedimethanol based on the total mole percent of ethylene glycol and 1,4-cyclohexanedimethanol, and the acid portion is terephthalic acid. In another embodiment of the present invention the polyester comprises structural units derived from terephthalic acid and a mixture of 1,4-cyclohexane dimethanol and ethylene glycol, wherein said cyclohexanedimethanol is greater than about 60 mole percent based on total moles of 1,4-cyclohexane dimethanol and ethylene glycol. In another embodiment, the polyester resin has an intrinsic viscosity of from about 0.4 to about 2.0 dl/g as measured in a 60:40 phenol/tetrachloroethane mixture at 23°-30° C. In one embodiment the stabilized composition of the present invention may optionally comprise at least one epoxy-functional polymer. The epoxy polymer is an epoxy functional (alkyl)acrylic monomer and at least one non-functional styrenic and/or (alkyl)acrylic monomer. In one embodiment of the present invention the epoxy polymer has at least one epoxy-functional (meth)acrylic monomer and at least one non-functional styrenic and/or (meth)acrylic monomer. These quenchers are characterized by relatively low molecular weights. In another embodiment the quenchers are epoxy-functional styrene (meth)acrylic copolymers produced from monomers of at least one epoxy functional (meth)acrylic monomer and at least one non-functional styrenic and/or (meth)acrylic monomer. As used herein, the term (meth) acrylic includes both acrylic and methacrylic monomers. Non limiting examples of epoxy-functional (meth)acrylic monomers include both acrylates and methacrylates. Examples of these monomers include, but are not limited to, those containing 1,2-epoxy groups such as glycidyl acrylate and glycidyl methacrylate. Other suitable epoxy-functional monomers include allyl glycidyl emer, glycidyl ethacrylate, and glycidyl itoconate. Suitable acrylate and methacrylate monomers include, but are not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-amyl acrylate, i-amyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, i-amyl methacrylate, s-butyl-methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, and isobornyl methacrylate. Non-functional acrylate and non-functional methacryl ate monomers include butyl acrylate, butyl methacryl ate, methyl methacrylate, iso-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 15 isobomyl acrylate and isobornyl methacrylate and combinations thereof are particularly suitable. Styrenic monomers for use in the present invention include, but are not limited to, styrene, alpha-methyl styrene, vinyl toluene, p-methyl styrene, t-butyl styrene, o-chlorostyrene, vinyl pyridine, and mixtures of these species. In certain embodiments the styrenic monomers for use in the present invention are 20 styrene and alpha-methyl styrene. In one embodiment of the present invention the epoxy functional polymer may also be used as a quencher. In one embodiment the claimed invention a catalyst may optionally be employed. If used, the catalyst can be any of the catalysts commonly used in the prior art such as alkaline earth metal oxides such as magnesium oxides, calcium oxide, barium oxide and zinc oxide; alkali and alkaline earth metal salts; a Lewis catalyst such as tin or tinanium compounds; a nitrogen-containing compound such as tetra-alkyl ammonium hydroxides used like the phosphonium analogues, e.g., tetra-alkyl phosphonium hydroxides or acetates. The Lewis acid catalysts and the catalysts can be used simultaneously. Inorganic compounds such as the hydroxides, hydrides, amides, carbonates, phosphates, borates, etc., of alkali metals such as sodium, potassium, lithium, cesium, etc., and of alkali earth metals such as calcium, magnesium, barium, etc., can be cited such as examples of alkali or alkaline earth metal compounds. Examples include sodium stearate, sodium carbonate, sodium acetate, sodium bicarbonate, sodium benzoate, sodium caproate, or potassium oleate. In one embodiment of the invention, the catalyst is selected from one of phosphonium salts or ammonium salts (not being based on any metal ion) for improved hydrolytic stability properties. In another embodiment of the invention, the catalyst is selected from one of: a sodium stearate, a sodium benzoate, a sodium acetate, and a tetrabutyl phosphonium acetate. In yet another embodiment of the present invention the catalysts is selected independently from a group of sodium stearate, zinc stearate, calcium stearate, magnesium stearate, sodium acetate, calcium acetate, zinc acetate, magnesium acetate, manganese acetate, lanthanum acetate, lanthanum acetylacetonate, sodium benzoate, sodium tetraphenyl borate, dibutyl tinoxide, antimony trioxide, sodium polystyrenesulfonate, PBT-ionomer, titanium isoproxide and tetraammoniumhydrogensulfate and mixtures thereof. In one embodiment of the present invention the thermoplastic composition comprises a mixture of stabilizers. In one embodiment of the present invention the thermoplastic resin composition comprises stabilizing additives. In another embodiment the stabilizing additives is a quenchers are used in the present invention to stop the polymerization reaction between the polymers. Quenchers are agents inhibit activity of any catalysts that may be present in the resins to prevent an accelerated interpolymerization and degradation of the thermoplastic. The suitability of a particular compound for use as a stabilizer and the determination of how much is to be used as a stabilizer may be readily determined by preparing a mixture of the polyester resin component and the polycarbonate and determining the effect on melt viscosity, gas generation or color stability or the formation of interpolymer. In one embodiment of the present invention the thermoplastic composition comprises at least two quenchers wherein the said quenchers are selected from a group consisting of phosphorous containing compounds, boric containing acids, aliphatic or aromatic carboxylic acids i.e., organic compounds the molecule of which comprises at least one carboxy group, anhydrides, polyols, and epoxy polymer. The choice of the quencher is essential to avoid color formation and loss of clarity of the thermoplastic composition. In one embodiment of the invention, the catalyst quenchers are phosphorus containing derivatives, such as organic phosphites as well as phosphorous acid. Examples include but are not limited to diphosphites, phosphonates, metaphosphoric acid; arylphosphinic and arylphosphonic acids. It should be noted that some quenchers, as in the class of phosphites, also provide the thermoplastic resin additional desirable properties, e.g., fire resistance. The favored stabilizers include an effective amount of an acidic phosphate salt; an acid, alkyl, aryl or mixed phosphite having at least one acidic hydrogen; a Group IB or Group IIB metal phosphate salt; a phosphorus oxo acid, a metal acid pyrophosphate or a mixture thereof. The acidic phosphate salts include sodium dihydrogen phosphate, mono zinc phosphate, potassium hydrogen phosphate, calcium dihydrogen phosphate and the like. The phosphites may be of the formula IX: where R13, R14 and R15 are independently selected from the group consisting of hydrogen, alkyl and aryl with the proviso that at least one of R13 R14 and R15 is hydrogen. The phosphate salts of a Group IB or Group IIB metal include zinc phosphate and the like. The phosphorus oxo acids include phosphorous acid, phosphoric acid, polyphosphoric acid or hypophosphorous acid. The polyacid pyrophosphates may be of the formula X: MzxHyPnO3n+1 (X) wherein M is a metal, x is a number ranging from 1 to 12 and y is a number ranging 1 to 12, n is a number from 2 to 10, z is a number from 1 to 5 and the sum of (zx)+y is equal to n+2. The preferred M is an alkaline or alkaline earth metal. The most preferred quenchers are oxo acids of phosphorus or acidic organo phosphorus compounds. In one embodiment of the present invention the quenchers are polyols that are admixed with the poly-carbonate and polyester. They may be represented by the formula XI. R16—(OH)r (XI) wherein, R16 is a substituted or unsubstituted aliphatic moiety, a substituted or unsubstituted aliphatic—aromatic moiety, preferably containing from 2 to about 20 carbon atoms and r is a positive integer having a value of from 2 up to the number of replaceable hydrogen atoms present on R16, preferably having a value of from 2 to about 12. In one embodiment of the present invention with the proviso that when R16 is a substituted or unsubstituted aliphatic-aromatic moiety the hydroxyl groups are bonded to the aliphatic portion of said moiety. In one embodiment of the invention the R16 is a substituted or unsubstituted aliphatic moieties include but not restricted to the acylic aliphatics and the cyclo-aliphatics. The acylic aliphatic moieties are preferably those containing from 2 to about 20 carbon atoms in either a straight chain or branched chain. In one embodiment of the present invention the cyclic aliphatic moieties are preferably those containing from 4 to about 8 ring carbon atoms. In another embodiment of the invention the cyclic aliphatic moieties may contain alkyl substituent groups on the ring carbon atoms, and the hydroxyl groups may be bonded to either the ring carbon atoms or to the alkyl substituent groups, or to both. In yet another embodiment R16 is a substituted or unsubstituted aliphatic-aromatic moieties containing an aromatic portion which preferably contains from 6 to 12 ring carbon atoms, which include but not limited to phenyl, naphthyl, and biphenyl, and an aliphatic portion bonded to the ring carbon atoms of the aromatic portion, with the hydroxyl groups being present only the aliphatic portion. In one embodiment the polyols of formula XI are the acylic aliphatic polyhydric alkanols, with the hexahydric alkanols being preferred. Preferred polyols of this type are those wherein the hydroxyl groups are bonded to different carbon atoms of the acylic aliphatic moiety. Some illustrative non-limiting examples of polyols represented by formula XI include cyclo-hexane dimethanol, butanediol, mannitol, sorbitol, 1,3-propanediol, glycerol, 1,2-cyclopentanediol, inositol, 1,3,5-cylcohexanetriol, 1,2,3,4,5-penta-hydrocypentane, and 1,1,2,2-tetrahydroxyethane. According to the present invention, the quencher may be a carboxylic acid derivative having the above formula XII. wherein X1 may be either zero or NH, X2 may be either OR18 or NHR18 and is always the former when X1 is NH. The R18 may be hydrogen, alkyl, aryl, radicals having up to 10 carbon atoms. In one embodiment Z may be CH or a substituted or unsubstituted aromatic carbocyclic radical. The substituents on the ring do not materially affect the character of the substituted carboxylic acid derivative for the purposes of this invention. The R17 is either hydrogen or a hydrocarbon-based radical including but not limited to both hydrocarbon and substituted hydrocarbon radicals, provided the substituents satisfy the above criterion. Most often, R17 is hydrogen, alkyl, or aryl radical that may contain substituents such as hydroxy, carboxy and carbalkoxy. In one embodiment the carbalkoxy radical is COOR18. In one embodiment of the present invention the substituted carboxylic acid derivatives used according to this invention may be but not limited to alpha.-hydroxy or alpha-amino aliphatic acid derivatives or o-hydroxy or o-amino aromatic acid derivatives. Illustrative compounds of this type are alkyl salicylate like for example, methyl salicylate, ethyl salicylate, aryl salicylate, salicylamide, glycine, malic acid, mandelic acid and dibutyl tartrate. The amount of the quencher added to the thermoplastic composition is an amount that is effective to stabilize the thermoplastic composition. In one embodiment the amount is at least about 0.001 weight percent, preferably at least about 0.01 weight percent based on the total amounts of said thermoplastic resin compositions. In another embodiment the amount of quencher mixture present should not exceed about 0.1 weight percent, preferably it should not exceed about 0.05 weight percent. In another embodiment the amount of quencher is in a range between about 25 and about 2000 parts per million percent based on the total amounts of the said thermoplastic composition. In yet another embodiment the amount of quencher is in a range between about 50 and about 1500 parts per million percent based on the total amounts of the said thermoplastic composition. In general, if less than about 0.01 weight percent of quencher mixture is present there is no appreciable stabilization of the thermoplastic composition. If a large amount of the quencher is used than some of the advantageous properties of the thermoplastic composition may be adversely affected. The amount of quencher used is thus an amount which is effective to stabilize the composition therein but insufficient to substantially deleteriously affect substantially most of the advantageous properties of said composition. The composition of the present invention may optionally include additional components which do not interfere with the previously mentioned desirable properties but enhance other favorable properties such as anti-oxidants, flame retardants, reinforcing materials, colorants, mold release agents, fillers, nucleating agents, UV light and heat stabilizers, lubricants, and the like. Additionally, additives such as antioxidants, minerals such as talc, clay, mica, barite, wollastonite and other stabilizers including but not limited to UV stabilizers, such as benzotriazole, supplemental reinforcing fillers such as flaked or milled glass, and the like, flame retardants, pigments or combinations thereof may be added to the compositions of the present invention. Flame-retardant additives are desirably present in an amount at least sufficient to reduce the flammability of the polyester resin, preferably to a UL94 V-0 rating. The amount will vary with the nature of the resin and with the efficiency of the additive. In general, however, the amount of additive will be from 2 to 30 percent by weight based on the weight of resin. A preferred range will be from about 15 to 20 percent. Typically halogenated aromatic flame-retardants include tetrabromobisphenol A polycarbonate oligomer, polybromophenyl ether, brominated polystyrene, brominated BPA polyepoxide, brominated imides, brominated polycarbonate, poly (haloaryl acrylate), poly (haloaryl methacrylate), or mixtures thereof. Examples of other suitable flame retardants are brominated polystyrenes such as polydibromostyrene and polytribromostyrene, decabromobiphenyl ethane, tetrabromobiphenyl, brominated alpha, omega-alkylene-bis-phthalimides, e.g. N,N′-ethylene-bis-tetrabromophthalimide, oligomeric brominated carbonates, especially carbonates derived from tetrabromobisphenol A, which, if desired, are end-capped with phenoxy radicals, or with brominated phenoxy radicals, or brominated epoxy resins. The flame retardants are typically used with a synergist, particularly inorganic antimony compounds. Such compounds are widely available or can be made in known ways. Typical, inorganic synergist compounds include Sb2O5, SbS3, sodium antimonate and the like. Especially preferred is antimony trioxide (Sb2O3). Synergists such as antimony oxides, are typically used at about 0.5 to 15 by weight based on the weight percent of resin in the final composition. Also, the final composition may contain polytetrafluoroethylene (PTFE) type resins or copolymers used to reduce dripping in flame retardant thermoplastics. Other additional ingredients may include antioxidants, and UV absorbers, and other stabilizers. Antioxidants include i) alkylated monophenols, for example: 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(alpha-methylcyclohexyl)-4,6 dimethylphenol, 2,6-di-octadecyl-4-methylphenol, 2,4,6,-tricyclohexyphenol, 2,6-di-tert-butyl-4-methoxymethylphenol; ii) alkylated hydroquinones, for example, 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butyl-hydroquinone, 2,5-di-tert-amyl-hydroquinone, 2,6-diphenyl-4octadecyloxyphenol; iii) hydroxylated thiodiphenyl ethers; iv) alkylidene-bisphenols; v) benzyl compounds, for example, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene; vi) acylaminophenols, for example, 4-hydroxy-lauric acid anilide; vii) esters of beta-(3,5-di-tert-butyl-4-hydroxyphenol)-propionic acid with monohydric or polyhydric alcohols; viii) esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols; vii) esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl) propionic acid with mono-or polyhydric alcohols, e.g., with methanol, diethylene glycol, octadecanol, triethylene glycol, 1,6-hexanediol, pentaerythritol, neopentyl glycol, tris(hydroxyethyl) isocyanurate, thiodiethylene glycol, N,N-bis(hydroxyethyl) oxalic acid diamide. Typical, UV absorbers and light stabilizers include i) 2-(2′-hydroxyphenyl)-benzotriazoles, for example, the 5′methyl-,3′5′-di-tert-butyl-,5′-tert-butyl-,5′(1,1,3,3-tetramethylbutyl)-,5-chloro-3′5′-di-tert-butyl-,5-chloro-3′tert-butyl-5′methyl-,3′sec-butyl-5′tert-butyl-,4′-octoxy,3′,5′-ditert-amyl-3′5′-bis-(alpha, alpha-dimethylbenzyl)-detivatives; ii) 2.2 2-Hydroxy-benzophenones, for example, the 4-hydroxy-4-methoxy-,4-octoxy,4-decloxy-,4-dodecyloxy-,4-benzyloxy,4,2′,4′-trihydroxy-and 2hydroxy-4,4′-dimethoxy derivative, and iii) esters of substituted and unsubstituted benzoic acids for example, phenyl salicylate, 4-tert-butylphenyl-salicilate, octylphenyl salicylate, dibenzoylresorcinol, bis-(4-tert-butylbenzoyl)-resorcinol, benzoylresorcinol, 2,4-di-tert-butyl-phenyl-3,5-di-tert-butyl-4-hydroxybenzoate and hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate. Phosphites and phosphonites stabilizers, for example, include triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tris(nonyl-phenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite tristearyl sorbitol triphosphite, and tetrakis(2,4-di-tert-butylphenyl)4,4′-biphenylene diphosphonite. Dyes or pigments may be used to give a background coloration. Dyes are typically organic materials that are soluble in the resin matrix while pigments may be organic complexes or even inorganic compounds or complexes which are typically insoluble in the resin matrix. These organic dyes and pigments include the following classes and examples: furnace carbon black, titanium oxide, phthalocyanine blues or greens, anthraquinone dyes, scarlet 3b Lake, azo compounds and acid azo pigments, quinacridones, chromophthalocyanine pyrrols, halogenated phthalocyanines, quinolines, heterocyclic dyes, perinone dyes, anthracenedione dyes, thioxanthene dyes, parazolone dyes, polymethine pigments and others. The range of composition of the thermoplastic resin of the present invention is from about 10 to 90 weight percent of the polycarbonate component, 90 to about 10 percent by weight of the polyester component. In one embodiment, the composition comprises about 25-75 weight percent polycarbonate and 75-25 weight percent of the polyester component. PROCESSING The method of blending the compositions can be carried out by conventional techniques. One convenient method comprises blending the polyester or polycarbonate and other ingredients in powder or granular form, extruding the blend and comminuting into pellets or other suitable shapes. The ingredients are combined in any usual manner, e.g., by dry mixing or by mixing in the melted state in an extruder, on a heated mill or in other mixers. Colorants may be added to the extruder downstream of the feed port. The thermoplastic resin of this invention can be processed by various techniques including but not limited to injection molding, blow molding, extrusion into sheet, film or profiles, compression molding. In one embodiment the blend of the present invention, polycarbonate, polyester, and optional additives thereof, is polymerized by extrusion at a temperature ranging from about 225 to 350° C. for a sufficient amount of time to produce a copolymer characterized by a single Tg. In the present invention, either a single or twin screw extruder can be used. The extruder should be one having multiple feeding points, allowing the catalyst quencher to be added at a location down-stream in the extruder. In one embodiment the process is a one pass process wherein all the components were mixed together and added in the feeder. In another embodiment the process is a one pass process wherein the catalyst is added at the beginning of the extrusion process via an upstream feeding point, and the quencher is added at the later portion of the extruder process via a downstream feeding point. Since the quencher is added downstream after the completion of the reaction, it has little or no impact on the haze of the composition. In one embodiment the catalyst is added at the beginning of the extrusion process via an upstream feeding point. The colored clear thermoplastic resin are then reloaded into the extruder and the quencher is added to the blend in the second pass via a downstream feeding point. Since the catalyst quencher is added downstream after the completion of the reaction, it has little or no impact on the haze of the composition. The residence time can be up to about 45 to 90 seconds. The rate at which polycarbonate, polyester and optional additives are delivered into the extruder for melt mixing depends on the design of the screws of the extruder. Characteristic residence times for the single-pass and double-pass extrusion process of the invention varies according to extrusion operating parameters, the screw design. The molten mixture of the optically clear thermoplastic resin composition so formed to particulate form, example by pelletizing or grinding the composition. The composition of the present invention can be molded into useful articles by a variety of means by many different processes to provide useful molded products such as injection, extrusion, rotation, foam molding calender molding and blow molding and thermoforming, compaction, melt spinning form articles. The thermoplastic composition of the present invention has additional properties of good mechanical properties, color stability, oxidation resistance, good flame retardancy, good processability, i.e. short molding cycle times, good flow, and good insulation properties. The articles made from the composition of the present invention may be used widely in house ware objects such as food containers and bowls, home appliances, as well as films, electrical connectors, electrical devices, computers, building and construction, outdoor equipment, trucks and automobiles. EXAMPLES Without further elaboration, it is believed that one skilled in the art can, using the description herein, utilize the present invention to its fullest extent. The following examples are included to provide additional guidance to those skilled in the art in practicing the claimed invention. The examples provided are merely representative of the work that contributes to the teaching of the present application. While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. Accordingly, these examples are not intended to limit the invention, as defined in the appended claims, in any manner. In the following examples values for glass transition temperatures (Tg) were determined by differential scanning calorimetry (DSC) at a heating rate of 20° C. per minute. Weight average molecular weights were measured by gel permeation chromatography (GPC) versus polystyrene standards using chloroform as solvent. The GPC column was a Mixed-C column with dimensions 300 millimeters (mm)×7.5 mm available from Polymer Laboratories. Yellow index or YI was measured on a Gardner Colorimeter model XL-835. The percentage transmission and haze were determined in accordance with test method ASTM D-1003. Melt volume rate was measured as per ISO Standard 1133, 265° C., 240 seconds, 2.16 Kg, and 0.0825 inch orifice. The heat distortion temperature (also known as HDT) test were performed by placing HDT samples edgewise, at load of 1.8 MPa and heating rate of 120C./hr (degree celsius/hr). Environmental stress cracking resistance was measured making tensile bars of the samples and they were subjected to a constant strain, these were then kept in an oven at 60° C. and the defects on the surface like cracks, crazes were checked. Flexural properties were measured using ISO 178 method. Flexural modulus was measured by ASTM D970 method at room temperature. Chemical resistance was measured on an extruded test piece (thickness=2.5 mm) was secured in 1% distortion jig and exposed various solvents for two days and the elongation at break was measured. The tensile properties were determined using ISO 527 and the Izod Impact were measured using the standard ISO 180/U method. Examples 1-11 In these example, 70 weight percent of polycarbonate available from General Electric Company as Lexan® polycarbonate resin was blended with a PCTG polyester from Eastman Chemicals (30 weight percent) and varying levels of a mixture of quenchers. The blends were compounded at 270° C. on a WP25 mm co-rotating twin screw extruder, yielding a pelletized composition. Compounding was carried out at a feed rate of about 15 kilo gram per hour and a screw speed of about 300 rotations per minute. Blends of polycarbonate and polyesters with quencher combinations have been prepared. The resulting pellets were dried for at least four hours at 100° C. before injection molding into ASTM/ISO test specimens on an 80 ton, four oz. injection molding machine operated at a temperature of about 280° C. Samples molded from the blends were tested for optical properties like % Transmission, % haze and yellow index. MVR is measure for all the blends and those samples were exposed to heat and humidity (80° C. and 80% RH) and MVR is measured after about seven days to measure the degradation in the blend which will in turn relate to hydrostability of the material. The results are indicated in Table 1. TABLE 1 PC/PCTG thermoplastic compositions with varying combinations of quenchers. Quencher 1 Quencher 2 Quencher 3 MVR- MVR-1 (ppm) (ppm) (ppm) YI Initial Wk % Change % T % H Ex. 1 H3PO4 (50) Malic Acid (50) — 2.99 9.5 11.5 21.05 90 3.57 Ex. 2 H3PO4 (50) Methyl Salicylate — 3.19 9.1 10.7 17.58 89.9 2.43 (50) Ex. 3 H3PO4 (33) Methyl Salicylate — 3.17 9 9.8 8.89 89.9 3.64 (50) Ex. 4 H3PO4 (17) Methyl Salicylate Boric acid 3.1 8.35 9.67 15.81 91 1.17 (33) (50) Ex. 5 H3PO4 (50) — Boric acid 2.1 8.65 10.7 23.70 91 1.04 (50) Ex. 6 — Methyl Salicylate Boric acid 4.6 8.3 9.3 12.05 90.7 0.96 (50) (50) Ex. 7 H3PO4 (25) — Boric acid 3.1 8.55 9.55 11.70 91 0.95 (75) Ex. 8 H3PO4 (25) Methyl Salicylate Boric acid- 2.8 8.7 9.65 10.92 91 1.78 (50) (25) Ex. 9 H3PO4 (50) Phenyl — 2.9 — — — 91 0.74 Phosphonic acid (50) Ex. 10 H3PO4 (50) Mannitol (100) — 2.02 — — — 91 0.93 Ex. 11 H3PO4 (50) Mannitol (150) — 2.04 — — — 91 0.95 Comparative Examples CEx.1-CEx.9 In these example, 70 weight percent of polycarbonate available from General Electric Company as Lexan® polycarbonate resin was blended with a PCTG polyester from Eastman Chemicals (30 weight percent) and varying levels of single quenchers. The blends were compounded at 270° C. on a WP25 mm co-rotating twin screw extruder, yielding a pelletized composition. Compounding was carried out at a feed rate of about 15 kilo gram per hour and a screw speed of about 300 rotations per minute. The resulting pellets were dried for at least four hours at 100° C. before injection molding into ASTM/ISO test specimens on an 80 ton, four oz. injection molding machine operated at a temperature of about 280° C. Samples molded from the blends were tested for optical properties like % Transmission, % haze and yellow index. MVR is measure for all the blends and those samples were exposed to heat and humidity (80° C. and 80% RH) and MVR is measured after about seven days to measure the degradation in the blend which will in turn related to hydrostability of the material. The results are indicated in Table 2. TABLE 2 % Change MVR- MVR-1 after 1 Quencher (ppm) YI Initial Wk Wk % T % H CEx. 1 Ph Acid (75) 2.3 11.85 14.9 25.74 88.55 2.05 CEx. 2 Malic Acid (250) 5.35 9.1 10.1 10.99 88.7 3.35 CEx. 3 Methyl Salicylate (100) 8.3 8.7 9.6 10.34 88.4 2.93 CEx. 4 Zinc Phosphate (500) 9.78 8.9 9.6 7.87 87.2 8.9 CEx. 5 Boric Acid (100) 4.6 8.55 9.25 8.19 90 1.2 CEx. 6 Sodium di-hydrogen ortho phosphate 5.52 8.7 9.5 9.20 86.87 12.47 (500) CEx. 7 Mannitol (200) 2.3 9.85 10.75 9.14 89.05 1.61 CEx. 8 D-Sorbitol (200) 1.58 9.5 10.25 7.89 89.3 2.47 CEx. 9 Phenyl Phosphonic acid (100) 3 8.9 10.1 13.48 88.9 0.95 Chemical resistance of the polycarbonate-PCTG blends is measured with respect to the elongation at break values for the samples after exposure to chemicals for two days. The percentage of the quenchers present in the composition is indicated. The data is given in Table 3. TABLE 3 Retention of Elongation at Break after two days of exposure (%) 1% Epoxy 2% Epoxy Chemical 75% H3PO4 polymer polymer No exposure 100 100 100 Oleic acid No strain 71 87 90 1% strain 4 15 17 Coppertone No strain 79 96 5 1% strain 47 2 2 Windex No strain 83 78 86 1% strain 5 4 4 Cascade No strain 89 96 96 1% strain Breaks 93 94 Vegetable oil No strain 81 92 86 1% strain 104 50 88 These data shows that thermoplastic compositions of the invention with a mixture of quenchers have beneficial properties and a balance of optical property, processability, solvent resistance and hydrostability in addition to good mechanical and thermal properties. While the invention has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present invention. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims. All Patents and published articles cited herein are incorporated herein by reference. | <SOH> BACKGROUND OF THE INVENTION <EOH>This invention relates to a stabilized thermoplastic resin composition, a method to synthesize the composition and articles made from the compositions. Polycarbonate is a useful engineering plastic for parts requiring clarity, high toughness, and, in some cases, good heat resistance. However, polycarbonate also has some important deficiencies, among them poor chemical and stress crack resistance, poor resistance to sterilization by gamma radiation, and poor processability. Blends of polyesters with polycarbonates provide thermoplastic compositions having improved properties over those based upon either of the single resins alone. Moreover, such blends are often more cost effective than polycarbonate alone. The miscibility of PC with the polyesters gives the blends the clarity needed, but this is restricted to (semi)aliphatic polyesters such as poly(cyclohexane dimethanol cyclohexane dicarboxylate) (PCCD) or a glycolized copolyester such as polyethylene glycol cyclohexane dimethanol terephthalate (PCTG). PCT patent application no. WO 02/38675 discloses a thermoplastic composition comprising PC, PCCD, and an impact modifier. U.S. Pat. No. 4,188,314, U.S. Pat. No. 4,125,572; U.S. Pat. No. 4,391,954; U.S. Pat. No. 4,786,692; U.S. Pat. Nos. 4,897,453, and 5,478,896 relate to blends of an aromatic polycarbonate and poly cyclohexane dimethanol phthalate. U.S. Pat. No. 4,125,572 relates to a blend of polycarbonate, polybutylene terephthalate (PBT) and an aliphatic/cycloaliphatic iso/terephthalate resin. U.S. Pat. No. 6,281,299 discloses a process for manufacturing transparent polyester/polycarbonate compositions, wherein the polyester is fed into the reactor after bisphenol A is polymerized to a polycarbonate. Moldable crystalline resin compositions such as polycarbonate-polyester blends are desirable for many applications. On exposure to high temperature and humidity, such blends may exhibit relatively poor hydrolytic stability. Another problem associated with these blends is due to ester-carbonate interchange, also known as trans esterification, which may lead to loss of mechanical properties. Catalyst quenchers are typically used to prevent such interchange reactions. However these catalyst quenchers can also promote degradation of polymer chains and contribute to decrease in hydrolytic stability. Conventionally phosphorus derivatives such as phosphoric acid, phosphates have been used as quenchers. U.S. Pat. Nos. 4,532,290, 4,555,540, 4,401,804, U.S. Pat. No. 20,030,032,725, describes the phosphorous-containing compounds include phosphoric acid, certain organic phosphorous compounds such as distearyl pentaerythritol diphosphate, mono or dihydogen phosphate are useful in deactivating metallic catalyst residues. The use of phosphite stabilizers is not satisfactory because of the tendency to be unstable to both hydrolysis and oxidation. U.S. Pat. No. 4,452,933 teaches the use of hydroxy or amino substituted carboxylic acid derivatives such as Methyl salicylate, Malic acid, Glycine or dibutyl tartrate to effectively inhibit ester-carbonate interchange reaction. The U.S. Pat. No. 4,560,722 discloses a stabilized polycarbonate polyester blend with boric acid as a stabilizer. EP Patent 02 72417 teaches the use of polyols as a color stabilizer stabilizing the polycarbonate polyester composition. U.S. Pat. No. 5,087,665 Chung et al. disclose a method of improving the hydrolytic stability of blends of polycarbonate and polyethylene terephthalate, by adding polyethylene to the blends. U.S. Pat. Nos. 5,411,999 and 5,596,049 describe the use of epoxy based material in conjugation with the catalyst quenchers to promote hydrolytic stability. However, a disadvantage is that the epoxy compounds were used in combination with metal catalyst, such as sodium stearate, which in turn may result in loss in polycarbonate molecular weight. U.S. Pat. No. 4,760,107 teaches a addition of a combination of an epoxide with polyols to polycarbonate polyester blends for color retention properties. European Patent Nos. EP 0 273149 and EP 0 497 818, describe additions of epoxy oligomeric materials to certain polyesters, disclose thermal stability in glass reinforced and/or flame-retarded polyester formulations. U.S. Pat. 5,300,546 relates to polyester compositions with mineral fillers giving a ceramic feel which have improved hydrolytic stability and melt viscosity stability. There is a continuing need for polycarbonate polyester blends having a good balance of optical property, processability, solvent resistance and hydrostability in addition to good mechanical and thermal properties. | <SOH> BRIEF DESCRIPTION OF THE INVENTION <EOH>The present inventors have unexpectedly discovered a thermoplastic resin composition comprising structural units derived at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester and a combination of at least two quenchers, wherein said quencher is selected from a group consisting of phosphorus compound, carboxylic acid, derivates of carboxylic acids, epoxy functional polymers and boron compound. Also disclosed is a synthesis method for the optically clear thermoplastic resin compositions of the present invention and articles derived from said composition. In an embodiment of the present invention discloses a stabilized thermoplastic resin composition comprising: structural units derived from at least one substituted or unsubstituted polycarbonate, at least one substituted or unsubstituted polyester, an epoxy functional polymers and a combination of at least one quenchers, wherein said quencher is selected from a group consisting of phosphorus compounds, carboxylic acid compounds, polyols, and boron compounds. In another embodiment of the present invention the stabilized composition of the present invention has improved properties. Various other features, aspects, and advantages of the present invention will become more apparent with reference to the following description, examples, and appended claims. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20070814 | 20050526 | 72528.0 | 0 | BUTTNER, DAVID J | STABILIZED POLYCARBONATE POLYESTER COMPOSITION | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,207 | ACCEPTED | Controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster | Controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster that include receiving in the content server from the network device a key management block for the cluster, a unique data token for the cluster, and an encrypted cluster id and calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. In typical embod0iments, calculating a binding key includes calculating a management key from the key management block for the cluster; calculating a content server device key from the management key and the content server device id; decrypting the encrypted cluster id with the content server device key; and calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. | 1. A method for controlling the delivery of broadcast encryption content for a network cluster from a content server outside the cluster, the method comprising: receiving in the content server from a network device a key management block for the cluster, a unique data token for the cluster, and a encrypted cluster id; and calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. 2. The method of claim 1 wherein calculating a binding key further comprises: calculating a management key from the key management block for the cluster; calculating a content server device key from the management key and the content server device id; decrypting the encrypted cluster id with the content server device key; and calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. 3. The method of claim 2 wherein calculating a content server device key further comprises hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. 4. The method of claim 2 wherein calculating the binding key with the management key, the unique data token for the cluster, and the cluster id further comprises hashing, with a one way cryptographic hashing algorithm, the management key, the unique data token for the cluster, and the cluster id. 5. The method of claim 1 further comprising encrypting in the network device a cluster id in dependence upon a content server device id for the content server. 6. The method of claim 5 further comprising receiving in the network device a content server device id. 7. The method of claim 5 wherein encrypting a cluster id further comprises: calculating a content server device key; and encrypting the cluster id with the content server device key. 8. The method of claim 7 wherein calculating a content server device key further comprises hashing, with a one way hash algorithm, the management key and the content server device id. 9. The method of claim 1 further comprising: encrypting the content for the cluster with a title key; encrypting the title key with the binding key; and packaging the encrypted title key with the encrypted content for the cluster. 10. A system for controlling the delivery of broadcast encryption content for a network cluster from a content server outside the cluster, the system comprising: means for receiving in the content server from a network device a key management block for the cluster, a unique data token for the cluster, and a encrypted cluster id; and means for calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. 11. The system of claim 10 wherein means for calculating a binding key further comprises: means for calculating a management key from the key management block for the cluster; means for calculating a content server device key from the management key and the content server device id; means for decrypting the encrypted cluster id with the content server device key; and means for calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. 12. The system of claim 11 wherein means for calculating a content server device key further comprises means for hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. 13. The system of claim 11 wherein means for calculating the binding key with the management key, the unique data token for the cluster, and the cluster id further comprises means for hashing, with a one way cryptographic hashing algorithm, the management key, the unique data token for the cluster, and the cluster id. 14. The system of claim 10 further comprising means for encrypting in the network device a cluster id in dependence upon a content server device id for the content server. 15. The system of claim 14 further comprising means for receiving in the network device a content server device id. 16. The system of claim 14 wherein means for encrypting a cluster id further comprises: means for calculating a content server device key; and means for encrypting the cluster id with the content server device key. 17. The system of claim 16 wherein means for calculating a content server device key further comprises means for hashing, with a one way hash algorithm, the management key and the content server device id. 18. The system of claim 10 further comprising: means for encrypting the content for the cluster with a title key; means for encrypting the title key with the binding key; and means for packaging the encrypted title key with the encrypted content for the cluster. 19. A computer program product for controlling the delivery of broadcast encryption content for a network cluster from a content server outside the cluster, the computer program product comprising: a recording medium; means, recorded on the recording medium, for receiving in the content server from a network device a key management block for the cluster, a unique data token for the cluster, and a encrypted cluster id; and means, recorded on the recording medium, for calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. 20. The computer program product of claim 19 wherein means, recorded on the recording medium, for calculating a binding key further comprises: means, recorded on the recording medium, for calculating a management key from the key management block for the cluster; means, recorded on the recording medium, for calculating a content server device key from the management key and the content server device id; means, recorded on the recording medium, for decrypting the encrypted cluster id with the content server device key; and means, recorded on the recording medium, for calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. 21. The computer program product of claim 20 wherein means, recorded on the recording medium, for calculating a content server device key further comprises means, recorded on the recording medium, for hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. 22. The computer program product of claim 20 wherein means, recorded on the recording medium, for calculating the binding key with the management key, the unique data token for the cluster, and the cluster id further comprises means, recorded on the recording medium, for hashing, with a one way cryptographic hashing algorithm, the management key, the unique data token for the cluster, and the cluster id. 23. The computer program product of claim 19 further comprising means, recorded on the recording medium, for encrypting in the network device a cluster id in dependence upon a content server device id for the content server. 24. The computer program product of claim 23 further comprising means, recorded on the recording medium, for receiving in the network device a content server device id. 25. The computer program product of claim 23 wherein means, recorded on the recording medium, for encrypting a cluster id further comprises: means, recorded on the recording medium, for calculating a content server device key; and means, recorded on the recording medium, for encrypting the cluster id with the content server device key. 26. The computer program product of claim 25 wherein means, recorded on the recording medium, for calculating a content server device key further comprises means, recorded on the recording medium, for hashing, with a one way hash algorithm, the management key and the content server device id. 27. The computer program product of claim 19 further comprising: means, recorded on the recording medium, for encrypting the content for the cluster with a title key; means, recorded on the recording medium, for encrypting the title key with the binding key; and means, recorded on the recording medium, for packaging the encrypted title key with the encrypted content for the cluster. | BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the invention is data processing, or, more specifically, methods, systems, and products for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster. 2. Description of Related Art With the advent of consumer digital technology, content such as music and movies are no longer bound to the physical media that carry it. Advances in consumer digital technology presents new challenges to content owners such as record labels, studios, distribution networks, and artists who want to protect their intellectual property from unauthorized reproduction and distribution. Recent advances in broadcast encryption offer an efficient alternative to more traditional solutions based on public key cryptography. In comparison with public key methods, broadcast encryption requires orders of magnitude less computational overhead in compliant devices. In addition, broadcast encryption protocols are one-way, not requiring any low-level handshakes, which tend to weaken the security of copy protection schemes. IBM has developed a content protection system based on broadcast encryption called extensible Content Protection, referred to as “xCP.” xCP supports a trusted domain called a ‘cluster’ that groups together a number of compliant devices. Content can freely move among these devices, but it is useless to devices that are outside the cluster. Each compliant device is manufactured with a set of device keys. A key management block (“KMB”) is a data structure containing an encryption of a management key using every compliant device key in the set of device keys for a compliant device. That is, a KMB contains a multiplicity of encrypted instances of a management key, one for every device key in the set of device keys for a device. Each compliant device, using one of its own device keys, is capable of extracting an encrypted management key from a key management block and decrypting it. That is, the management key for a cluster is calculated from the key management block, and it is the ability to calculate a management key from a key management block that distinguishes compliant devices. A cluster is a private domain. Compliant devices can join a cluster. Some compliant devices in a cluster have specialized functions. Most devices do not store key management blocks; they read key management blocks from the cluster. A ‘kmbserver,’ however, is a device that stores the key management block and can update it. ‘Authorizers’ are network devices that can authorize other devices to join a cluster. In a compliant cluster, when a consumer purchases a device and installs it in his home, the device automatically determines which cluster is currently present, identifies an authorizer, and asks to join the cluster. In this specification, a network device that supports both an authorizer and an kmbserver is called a ‘cluster server.’ Each piece of content or each content stream in the home is protected with a unique key. These keys are called title keys. Each title key is encrypted with a master key for the particular home, called a binding key. To play protected content, a device reads the encrypted title key embedded in the content file and decrypts it with the binding key. Then, with the title key, the device decrypts the content itself. The binding key is calculated as the cryptographic hash of three quantities: the management key, the cluster ID, and a hash of the cluster's authorization table. The cluster ID is a unique identification code for a cluster established at cluster startup. The network authorization table is a simple file whose records represent the list of devices in the cluster. Content providers need a binding key for a cluster to encrypt title keys to provide content encrypted so that it can only be decrypted by devices in the cluster. One way to get a cluster's binding key to a content server is for the content server to join the cluster. A content server, acting as a compliant device, may join a cluster as follows: The content server broadcasts a “whosthere” message to a cluster network. A cluster server answers with an “imhere” message, including cluster name, cluster server deviceID, cluster server device type, the cluster KMB, and a hash of a cluster authorization table. The content server downloads the KMB from the cluster server. The content server computes the cluster management key from the KMB and its own device keys. The content server computes a message authorization code (“MAC”) by cryptographically hashing the management key with the content server's deviceID and the content server's device type code. The content server sends an authorization request to the cluster server, including the content server's deviceID and device type. The cluster server computes the management key using the KMB and its own device keys. This management key is the same as the management key computed by the content server. The cluster server computes the MAC using the content server's deviceID and device type, verifying the MAC received from the content server. If the MAC matches, the cluster server adds the content server to its authorization table. The cluster server sends an ‘authorized’ message to the content server, including an encrypted clusterID, encrypted with a content server key created by hashing the management key and the content server's deviceID. The content server generates the content server key by hashing the management key and the content server's deviceID and uses the content server key to decrypt the encrypted clusterID. The content server downloads the new authorization table from the cluster server. The content server computes the binding key for the cluster by hashing the management key, a hash of the new authorization table, and the clusterID. There are some drawbacks to this procedure. The content server broadcasts messages to clusters, which is not an appropriated procedure for a content server to perform. In addition, this procedure adds the content server as a device in the cluster, counting as a device against any maximum device count and changing the authorization table for the cluster. Moreover, the procedure is lengthy. There is an ongoing need for improvement therefore in procedures for controlling broadcast encryption of content for a network cluster from a content server outside the cluster. SUMMARY OF THE INVENTION Methods, systems, and products are disclosed for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster that include receiving in the content server from the network device a key management block for the cluster, a unique data token for the cluster, and an encrypted cluster id and calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. In typical embodiments, calculating a binding key includes calculating a management key from the key management block for the cluster; calculating a content server device key from the management key and the content server device id; decrypting the encrypted cluster id with the content server device key; and calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. In typical embodiments, calculating a content server device key includes hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. In typical embodiments, calculating the binding key with the management key, the unique data token for the cluster, and the cluster id includes hashing, with a one way cryptographic hashing algorithm, the management key, the unique data token for the cluster, and the cluster id. Typical embodiments also include encrypting in the network device a cluster id in dependence upon a content server device id for the content server. Many embodiments also include receiving in the network device a content server device id. In typical embodiments, encrypting a cluster id includes calculating a content server device key and encrypting the cluster id with the content server device key. In typical embodiments, calculating a content server device key includes hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. Typical embodiments also include encrypting the title key with the binding key; embedding the encrypted title key in content for the cluster; and encrypting with a title key the content for the cluster. The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 sets forth a line drawing of an exemplary network architecture in which methods and systems according to embodiments of the present invention may be implemented. FIG. 2 sets forth a data flow diagram illustrating an exemplary method for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster. FIG. 3 sets forth a data flow diagram illustrating an exemplary method of calculating a binding key. FIG. 4 sets forth a data flow diagram illustrating an exemplary method for encrypting a cluster id in a network device. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Introduction The present invention is described to a large extent in this specification in terms of methods for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster. Persons skilled in the art, however, will recognize that any computer system that includes suitable programming means for operating in accordance with the disclosed methods also falls well within the scope of the present invention. Suitable programming means include any means for directing a computer system to execute the steps of the method of the invention, including for example, systems comprised of processing units and arithmetic-logic circuits coupled to computer memory, which systems have the capability of storing in computer memory, which computer memory includes electronic circuits configured to store data and program instructions, programmed steps of the method of the invention for execution by a processing unit. The invention also may be embodied in a computer program product, such as a diskette or other recording medium, for use with any suitable data processing system. Embodiments of a computer program product may be implemented by use of any recording medium for machine-readable information, including magnetic media, optical media, or other suitable media. Persons skilled in the art will immediately recognize that any computer system having suitable programming means will be capable of executing the steps of the method of the invention as embodied in a program product. Persons skilled in the art will recognize immediately that, although most of the exemplary embodiments described in this specification are oriented to software installed and executing on computer hardware, nevertheless, alternative embodiments implemented as firmware or as hardware are well within the scope of the present invention. Controlling Delivery of Broadcast Encryption Content for a Network Cluster from a Content Server Outside the Cluster Methods, systems, and products are disclosed for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster that operate generally by providing the content server with enough information for it to package content for a specific cluster. FIG. 1 sets forth a line drawing of an exemplary network architecture in which methods and systems according to embodiments of the present invention may be implemented. The network of FIG. 1 includes an xPC compliant network cluster (320) that includes several xPC compliant network devices including an MP3 player (108), a television (110), a DVD player (106), and a personal computer (104). The network cluster supports a key management block (308) for the cluster, an authorization table (102) that identifies all the devices currently authorized to join the cluster, a binding key (316) for the cluster, and a cluster ID (416). The key management block (308) is a data structure containing an encryption of a management key with every compliant device key. That is, the key management block contains a multiplicity of encrypted instances of a management key, one for every device key in the set of device keys for a device. The binding key (316) for the cluster is calculated as a cryptographic hash of a management key, a cluster ID, and a unique data token for the cluster. The management key for the cluster is calculated from the key management block (308) and device keys. The network of FIG. 1 includes a content server (318) that is capable of encrypting content with title keys provided to it by content providers, content owners, or a legal licensing authority. Content server (318) is also capable of calculating a binding key for a cluster, given enough information about the cluster, and using the binding key to encrypt a title key and package it with encrypted contents. More particularly, content server (318) may control broadcast encryption of content for a network cluster (320) from outside the cluster by receiving from a network device in the cluster a key management block (308) for the cluster (320), a unique data token for the cluster (320), and an encrypted cluster id. The content server is capable of using the key management block (308) for the cluster (320), the unique data token for the cluster (320), and the encrypted cluster id to calculate the binding key for the cluster. For further explanation, FIG. 2 sets forth a data flow diagram illustrating an exemplary method for controlling delivery of broadcast encryption content for a network cluster (320) from a content server (318) outside the cluster (320) that includes receiving (302) in the content server (318) from the network device (322) a key management block (308) for the cluster (320), a unique data token (310) for the cluster (320), and an encrypted cluster id (312). The unique data token (310) typically is produced by the network device (322) as a data value to be unique to the cluster at the time when it is received (302) in the content server (318). Examples of unique data tokens include a random number generated in the network device, a hash of an authorization table for the cluster, and others as will occur to those of skill in the art. The method of FIG. 2 also includes calculating (304) a binding key (316) for the cluster (320) in dependence upon the key management block (308) for the cluster (320), the unique data token (310) for the cluster (320), and the encrypted cluster id (312). The method of FIG. 2 also includes encrypting (328) the content (334) for the cluster with a title key (330), encrypting (324) the title key (330) with the binding key (316); and packaging (326) the encrypted title key (332) with the encrypted content (336) for the cluster. In the example of FIG. 2, the message structure (306) for the key management block (308), the unique data token (310), and the encrypted cluster id (312) is referred to as a ‘customize message’ because the effect of encrypting the content for the cluster with a title key, encrypting the title key with the binding key, and packaging the encrypted title key with the encrypted content for the cluster is to create content that is ‘customized’ in that only devices in that cluster can decrypt it. Encrypting the content for the cluster with a title key, encrypting the title key with the binding key, and packaging the encrypted title key with the encrypted content for the cluster prepares content for distribution to a requesting network device. This procedure involves no authentication of a requesting device by the content server because the process produces content encrypted with a title key that is in turn encrypted with a binding key so that the title key can only be decrypted in a network device in a cluster using that exact binding key. The content server may freely offer the content to any device that requests it. Only devices in a cluster having that binding key can decrypt the content. The content server may calculate the binding key for a cluster, encrypt content for the cluster, and download the content all as part of a single overall transaction, for example, on a pay per view or pay per file type of transaction, where the content server does not retain the binding key beyond the duration of the single transaction. Alternatively, the content server may provide a subscription service, for example, in which it advantageously retains a cluster's binding key for a longer period of time. In such a case, the content server advantageously associates with the binding key in computer memory an identifier for the cluster, such as, for example, a requesting device ID or a base URL for the requesting device communicated to the content server as part of an initial handshake, for example. FIG. 3 sets forth a data flow diagram illustrating an exemplary method of calculating (304) a binding key (316) that includes calculating (402) a management key (410) from the key management block (308) for the cluster. A key management block may be implemented, for example, as a matrix of encrypted management keys, that is, a matrix made of the encryption of the management key using each different device key. A network device, in this example, content server (318), that knows a position in the matrix that was encrypted with its device key can calculate a management key by decrypting the value found at that position. The result is the management key. The method of FIG. 3 also includes calculating (404) a content server device key (414) from the management key (410) and the content server device id (412). In the method of FIG. 3, calculating (404) a content server device key (414) is carried out by hashing, with a one way cryptographic hash algorithm, the management key (410) and the content server device id (412). The method of FIG. 3 also includes decrypting (406) the encrypted cluster id (312) with the content server device key (414). The method of FIG. 3 also includes calculating (408) the binding key (316) with the management key (410), the unique data token (310) for the cluster, and the cluster id (416). In the method of FIG. 3, calculating (408) the binding key (316) with the management key (410), the unique data token (310) for the cluster, and the cluster id (416) is carried out by hashing, with a one way cryptographic hashing algorithm, the management key (410), the unique data token (310) for the cluster, and the cluster id (416). FIG. 4 sets forth a data flow diagram illustrating an exemplary method for encrypting (504) in the network device (322) a cluster id (416) in dependence upon a content server device id (412) for the content server (318). The method of FIG. 4 includes receiving (502) in the network device (322) a content server device id (412) from a content server (318). Alternatively, the network device receives the content server device ID (412) by retrieving the content server device ID from a content server device ID table, a network location, an on-line directory, or from any other source as will occur to those of skill in the art. In the method of FIG. 4, encrypting (504) a cluster ID (416) includes calculating (506) a content server device key (414) and encrypting (508) the cluster id (416) with the content server device key (414). In the method of FIG. 4, calculating (506) a content server device key (414) is carried out by hashing (510), with a one way cryptographic hash algorithm, the management key (410) and the content server device id (412). For further explanation, a use case is presented that illustrates a content server calculating a binding key for a cluster where the content server's device ID is provided to a network device in the cluster as part of an initial handshake: A network device sends a request for a binding server to prepare content for use in the device's cluster. The content server sends its content server device ID to a network device in a cluster. The network device calculates a content server key as a hash of the management key for the cluster and the content server device ID. The network device uses the content server key to encrypt its cluster ID. The network device produces a unique data token for its cluster. The network device sends to the content server the key management block for the cluster, the network device ID, the unique data token for the cluster, and the encrypted cluster ID. The content server encrypts content for the cluster with a title key. The content server computes the management key from the key management block using its own device key. The content server computes the content server key as a hash of the management key and the content server device ID. The content server decrypts the cluster ID with the content server key. The content server creates a binding key as a hash of the management key, the unique data token for the cluster, and the now decrypted cluster ID. The content server encrypts the title key with the binding key. The content server packages the encrypted title key with the content. The content server sends the packaged encrypted content and encrypted title key to the network device. Beginning with a request from a network device, this procedure involves no broadcast from the content server. The initial request is decoupled from any download of content which may occur as part of the same overall transaction with the request for preparation of content or may occur later or over a period of time. In this procedure, the content server does not join the cluster and the content server's operations therefore have no effect on the cluster's authorization table. It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present invention without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. The scope of the present invention is limited only by the language of the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The field of the invention is data processing, or, more specifically, methods, systems, and products for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster. 2. Description of Related Art With the advent of consumer digital technology, content such as music and movies are no longer bound to the physical media that carry it. Advances in consumer digital technology presents new challenges to content owners such as record labels, studios, distribution networks, and artists who want to protect their intellectual property from unauthorized reproduction and distribution. Recent advances in broadcast encryption offer an efficient alternative to more traditional solutions based on public key cryptography. In comparison with public key methods, broadcast encryption requires orders of magnitude less computational overhead in compliant devices. In addition, broadcast encryption protocols are one-way, not requiring any low-level handshakes, which tend to weaken the security of copy protection schemes. IBM has developed a content protection system based on broadcast encryption called extensible Content Protection, referred to as “xCP.” xCP supports a trusted domain called a ‘cluster’ that groups together a number of compliant devices. Content can freely move among these devices, but it is useless to devices that are outside the cluster. Each compliant device is manufactured with a set of device keys. A key management block (“KMB”) is a data structure containing an encryption of a management key using every compliant device key in the set of device keys for a compliant device. That is, a KMB contains a multiplicity of encrypted instances of a management key, one for every device key in the set of device keys for a device. Each compliant device, using one of its own device keys, is capable of extracting an encrypted management key from a key management block and decrypting it. That is, the management key for a cluster is calculated from the key management block, and it is the ability to calculate a management key from a key management block that distinguishes compliant devices. A cluster is a private domain. Compliant devices can join a cluster. Some compliant devices in a cluster have specialized functions. Most devices do not store key management blocks; they read key management blocks from the cluster. A ‘kmbserver,’ however, is a device that stores the key management block and can update it. ‘Authorizers’ are network devices that can authorize other devices to join a cluster. In a compliant cluster, when a consumer purchases a device and installs it in his home, the device automatically determines which cluster is currently present, identifies an authorizer, and asks to join the cluster. In this specification, a network device that supports both an authorizer and an kmbserver is called a ‘cluster server.’ Each piece of content or each content stream in the home is protected with a unique key. These keys are called title keys. Each title key is encrypted with a master key for the particular home, called a binding key. To play protected content, a device reads the encrypted title key embedded in the content file and decrypts it with the binding key. Then, with the title key, the device decrypts the content itself. The binding key is calculated as the cryptographic hash of three quantities: the management key, the cluster ID, and a hash of the cluster's authorization table. The cluster ID is a unique identification code for a cluster established at cluster startup. The network authorization table is a simple file whose records represent the list of devices in the cluster. Content providers need a binding key for a cluster to encrypt title keys to provide content encrypted so that it can only be decrypted by devices in the cluster. One way to get a cluster's binding key to a content server is for the content server to join the cluster. A content server, acting as a compliant device, may join a cluster as follows: The content server broadcasts a “whosthere” message to a cluster network. A cluster server answers with an “imhere” message, including cluster name, cluster server deviceID, cluster server device type, the cluster KMB, and a hash of a cluster authorization table. The content server downloads the KMB from the cluster server. The content server computes the cluster management key from the KMB and its own device keys. The content server computes a message authorization code (“MAC”) by cryptographically hashing the management key with the content server's deviceID and the content server's device type code. The content server sends an authorization request to the cluster server, including the content server's deviceID and device type. The cluster server computes the management key using the KMB and its own device keys. This management key is the same as the management key computed by the content server. The cluster server computes the MAC using the content server's deviceID and device type, verifying the MAC received from the content server. If the MAC matches, the cluster server adds the content server to its authorization table. The cluster server sends an ‘authorized’ message to the content server, including an encrypted clusterID, encrypted with a content server key created by hashing the management key and the content server's deviceID. The content server generates the content server key by hashing the management key and the content server's deviceID and uses the content server key to decrypt the encrypted clusterID. The content server downloads the new authorization table from the cluster server. The content server computes the binding key for the cluster by hashing the management key, a hash of the new authorization table, and the clusterID. There are some drawbacks to this procedure. The content server broadcasts messages to clusters, which is not an appropriated procedure for a content server to perform. In addition, this procedure adds the content server as a device in the cluster, counting as a device against any maximum device count and changing the authorization table for the cluster. Moreover, the procedure is lengthy. There is an ongoing need for improvement therefore in procedures for controlling broadcast encryption of content for a network cluster from a content server outside the cluster. | <SOH> SUMMARY OF THE INVENTION <EOH>Methods, systems, and products are disclosed for controlling delivery of broadcast encryption content for a network cluster from a content server outside the cluster that include receiving in the content server from the network device a key management block for the cluster, a unique data token for the cluster, and an encrypted cluster id and calculating a binding key for the cluster in dependence upon the key management block for the cluster, the unique data token for the cluster, and the encrypted cluster id. In typical embodiments, calculating a binding key includes calculating a management key from the key management block for the cluster; calculating a content server device key from the management key and the content server device id; decrypting the encrypted cluster id with the content server device key; and calculating the binding key with the management key, the unique data token for the cluster, and the cluster id. In typical embodiments, calculating a content server device key includes hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. In typical embodiments, calculating the binding key with the management key, the unique data token for the cluster, and the cluster id includes hashing, with a one way cryptographic hashing algorithm, the management key, the unique data token for the cluster, and the cluster id. Typical embodiments also include encrypting in the network device a cluster id in dependence upon a content server device id for the content server. Many embodiments also include receiving in the network device a content server device id. In typical embodiments, encrypting a cluster id includes calculating a content server device key and encrypting the cluster id with the content server device key. In typical embodiments, calculating a content server device key includes hashing, with a one way cryptographic hash algorithm, the management key and the content server device id. Typical embodiments also include encrypting the title key with the binding key; embedding the encrypted title key in content for the cluster; and encrypting with a title key the content for the cluster. The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention. | 20040331 | 20080812 | 20051013 | 65593.0 | 0 | KYLE, TAMARA TESLOVICH | CONTROLLING DELIVERY OF BROADCAST ENCRYPTION CONTENT FOR A NETWORK CLUSTER FROM A CONTENT SERVER OUTSIDE THE CLUSTER | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,279 | ACCEPTED | Variable shear line lock cylinder | A lock cylinder is provided and includes an outer cylinder having a bore, an inner cylinder rotatably disposed within the bore, and a pin assembly disposed within the inner and outer cylinders. The pin assembly is operable to selectively lock the inner cylinder relative to the outer cylinder. The pin assembly includes an upper shear cylinder positionable relative to the outer cylinder and a lower shear cylinder positionable relative to the inner cylinder. The upper and lower shear cylinders are movable to define a first shear line therebetween. In addition, the pin assembly includes an upper pin slidable within the upper shear cylinder and a lower pin slidable within the lower shear cylinder, whereby the upper and lower pins define a second shear line therebetween. The lock cylinder is positionable from a locked position to an unlocked position when the first shear line is aligned with the second shear line. | 1. A lock cylinder comprising: an outer cylinder having a first bore formed along a first longitudinal axis; an inner cylinder rotatably disposed within said first bore; a plurality of pin assemblies disposed within said inner and outer cylinders, said plurality of pin assemblies being operable to selectively lock said inner cylinder relative to said outer cylinder, each of said plurality of pin assemblies comprising: an upper shear cylinder positionable relative to said outer cylinder; a lower shear cylinder positionable relative to said inner cylinder, said upper and lower shear cylinders movable to define a first shear line therebetween; an upper pin slidable within said upper shear cylinder; and a lower pin slidable within said lower shear cylinder, said upper and lower pins defining a second shear line therebetween at a shear interface; wherein the lock cylinder is positionable from a locked position to an unlocked position when said first shear line is aligned with said second shear line, the plurality of shear interfaces cooperating to define an irregular shear interface between the inner and outer cylinders. 2-15. (canceled) 16. A lock cylinder comprising: an outer cylinder having a first bore formed along a first longitudinal axis; an inner cylinder rotatably disposed within said first bore; a an irregular shear zone defined between said outer and inner cylinders; a plurality of pin assemblies disposed within said inner and outer cylinders, said plurality of pin assemblies operable to selectively lock said inner cylinder relative to said outer cylinder, each of said plurality of pin assemblies comprising: an upper shear cylinder positionable relative to said outer cylinder; a lower shear cylinder positionable relative to said inner cylinder, said upper and lower shear cylinders movable to define a first shear line therebetween; and an upper lock rack, said upper lock rack operable to lock said upper shear cylinder in a plurality of positions relative to said outer cylinder; and a lower lock rack, said lower lock rack operable to lock said lower shear cylinder in a plurality of positions relative said inner cylinder; wherein said upper and lower lock racks lock said upper and lower shear cylinders relative said inner and outer cylinders to maintain said first shear line within said shear zone, said inner cylinder being movable relative to said outer cylinder when the plurality of shear lines lie within the shear zone. 17-26. (canceled) 27. A method of re-keying a lock cylinder comprising: inserting a first key into said lock cylinder, said first key operable to allow rotation of an inner cylinder relative an outer cylinder; providing a lock assembly having a longitudinal axis, the lock assembly being operable to lock said inner cylinder to said outer cylinder and including a plurality of pin assemblies, each of the plurality of pin assemblies including an upper pin, upper shear cylinder, lower pin, and lower shear cylinder, the upper and lower pins and the upper and lower shear cylinders of each of the Plurality of pin assemblies cooperating to define a shear interface, at least one of the plurality of shear interfaces being disposed at a different transverse distance relative to the remaining shear interfaces; translating a first lock pin within said upper shear cylinder and out of engagement with an upper lock rack; engaging said first lock pin with said upper shear cylinder and said upper pin; translating a second lock pin within said lower shear cylinder and out of engagement with a lower lock rack; engaging said second lock pin with said lower shear cylinder and said lower pin; removing said first key; providing a force to said upper shear cylinder, said force operable to set said upper and lower shear cylinders in a first position relative said upper and lower lock racks; inserting a second key into said lock cylinder, said second key including an engagement surface operable to engage said second pin; positioning said upper shear cylinder, upper pin, lower shear cylinder, and lower pin relative said upper and lower lock racks via said second key; disengaging said upper lock pin from said upper pin; engaging said first lock pin with said upper lock rack and said upper shear cylinder; disengaging said second lock pin from said lower pin; engaging said second lock pin with said lower lock rack and said lower shear cylinder. 28. (Canceled) 29. The method according to claim 27 wherein said force is applied by a spring. 30. A method of re-keying a lock cylinder comprising: providing a lock cylinder having a cylinder body, a plug body, and a plurality of pin positions, each pin position having a longitudinal axis and a shear interface movable along the longitudinal axis, each of the plurality of shear interfaces being operatively disposed at different transverse distances from the longitudinal axis to unlock the lock cylinder; inserting a first valid key in the cylinder to move each shear interface along its respective longitudinal axis; rotating the lock cylinder from a home position to a learn position; replacing the first valid key with a second valid key; rotating the lock cylinder back to the home position; and removing the second valid key. 31. A lock cylinder comprising: a cylinder body and a plug body rotatable therein; and a plurality of pin positions, each pin position having a longitudinal axis and a shear interface movable along the longitudinal axis, the plurality of shear interfaces cooperating to define an irregular shear zone between the cylinder body and the plug body. | FIELD OF THE INVENTION The present invention relates to lock cylinders, and more particularly, to an improved lock cylinder and method of re-keying a lock cylinder. BACKGROUND OF THE INVENTION It is well known in the art to provide a door hardware assembly that is operable to maintain a door in a closed position by selectively securing the door to a doorframe. It is equally well known to provide a door hardware assembly that is capable of being locked to selectively prevent operation of the door hardware assembly. As can be appreciated, by preventing operation of the door hardware assembly, the door will remain closed and in a locked condition. Such conventional door hardware assemblies generally include a handle assembly, lock cylinder, and key, whereby the key is operable to selectively lock the lock cylinder to prevent operation of the door handle assembly and maintain the door in the closed and locked condition. Conventional door hardware assemblies are typically disposed on a door proximate to an edge of the door for selective engagement with a striker assembly mounted on a door frame. As previously discussed, door hardware assemblies commonly include a handle assembly, lock cylinder, and key. The lock cylinder is designed to matingly receive a key, whereby the key is operable to toggle the lock cylinder between a locked and unlocked condition. The unlocked condition of the lock cylinder permits rotation of the handle assembly and, thus, movement of the door relative the doorframe. The locked condition prohibits rotation of the handle assembly, thereby maintaining the door in a closed and locked condition. As can be appreciated, the key is specific to the particular lock cylinder so as to prevent unwanted operation of the door handle assembly and movement of the door relative the doorframe. In this regard, a lost or stolen key may provide unwanted operation of the lock cylinder and unwanted access through the door. For at least this reason, being able to “reset” or “re-key” the lock cylinder, without having to replace the entire mechanism, is a desirable feature. In this regard, conventional door hardware assemblies commonly provide for adjustment of a locking mechanism disposed within the lock cylinder. Re-keying of a conventional lock cylinder provides the lock cylinder with a new key that is operable to lock and unlock the re-configured lock cylinder, while concurrently prohibiting further use of the lost key. Such lock cylinders commonly include a plurality of pin assemblies, whereby each pin assembly includes an upper pin slidably disposed within an upper shear cylinder and a lower pin slidably disposed within a lower shear cylinder. The upper and lower shear cylinders are axially aligned such that a first shear zone is formed between the upper and lower pins and a second shear zone is formed between the upper and lower shear cylinders. As previously discussed, a key is used to selectively lock and unlock the lock cylinder, whereby raised portions disposed on the key are operable to engage the upper and lower pins to properly align the second shear zone with the first shear zone. Proper alignment of the first and second shear zones allows each pin to disengage the respective shear cylinder and permit rotation of the door handle assembly. In a re-keying operation, the upper and lower pins are adjusted to vary the relative heights of each of the upper and lower pins. In this regard, a new key having raised portions commensurate with the new pin heights of each pin assembly, is required to properly align the first and second shear zones of the upper and lower pins. Once the new pins are installed, the lock cylinder will no longer permit rotation of the door handle assembly if the old key is used in the lock cylinder. As can be appreciated, the old key is not commensurate with the new pin heights and therefore will not properly align the first and second shear zones of the respective pin assemblies. While conventional lock cylinders adequately provide for a re-keying operation of a lock cylinder, they suffer from the disadvantage of requiring partial disassembly of the lock cylinder and typically require a specialized technician, such as a locksmith, to perform the re-keying operation. Further, conventional lock cylinders suffer from the disadvantage of requiring various pin heights and combinations thereof to properly re-key the cylinder. Further yet, conventional re-keying kits require door hardware manufacturers to produce varying pin heights for each kit, thereby overproducing the required number of individual pins to simply re-key one lock cylinder. Therefore, a lock cylinder that provides for a re-keying operation without requiring disassembly of the lock cylinder is desirable in the industry. Furthermore, a lock cylinder that is capable of being re-keyed without replacing the existing components is also desirable. Further yet, a lock cylinder that provides for a re-keying operation without requiring a plurality of additional pins with varying pin heights is also desirable. SUMMARY OF THE INVENTION Accordingly, the present invention provides a lock cylinder including an outer cylinder having a first bore formed along a first longitudinal axis, an inner cylinder rotatably disposed within the first bore, and a pin assembly disposed within the inner and outer cylinders. The pin assembly is operable to selectively lock the inner cylinder relative to the outer cylinder. The pin assembly includes an upper shear cylinder positionable relative to the outer cylinder and a lower shear cylinder positionable relative to the inner cylinder, whereby the upper and lower shear cylinders are movable to define a first shear line therebetween. In addition, the pin assembly includes an upper pin slidable within the upper shear cylinder and a lower pin slidable within the lower shear cylinder, whereby the upper and lower pins define a second shear line therebetween. The lock cylinder is positionable from a locked position to an unlocked position when the first shear line is aligned with the second shear line. In addition, upper and lower lock racks are provided to lock the upper and lower shear cylinders relative to the inner and outer cylinders. Specifically, the upper lock rack is operable to lock the upper shear cylinder relative to the outer cylinder while the lower lock rack is operable to lock the lower shear cylinder relative to the inner cylinder. In this regard, the upper and lower lock racks are operable to position the first shear line in one of a plurality of positions relative to the inner and outer cylinders to vary the position of the first shear line during a re-keying operation. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: FIG. 1 is a perspective view of a lock cylinder in accordance with the principals of the present invention; FIG. 2 is a sectional view of the lock cylinder of FIG. 1 taken along the line A-A; FIG. 3 is a sectional view of the lock cylinder of FIGS. 1 and 2 in a locked position; FIG. 4 is a more detailed cross-sectional view of particular components of FIG. 3; FIG. 5 is a more detailed cross-sectional view of particular components of FIG. 3; FIG. 6 is a sectional view of the lock cylinder of FIGS. 1 and 2 in an unlocked position; FIG. 7 is a sectional view of the lock cylinder of FIGS. 1 and 2 in a locked position showing an inner cylinder rotating relative an outer cylinder; FIG. 8 is a sectional view of the lock cylinder of FIGS. 1 and 2 in a learn mode showing an upper shear cylinder in a reset position and a lower shear cylinder in a reset position; FIG. 9 is a sectional view of the lock cylinder of FIGS. 1 and 2 in a learn mode showing a new key re-positioning an upper shear cylinder and lower shear cylinder relative an outer and inner cylinder; and FIG. 10 is a sectional view of the lock cylinder of FIGS. 1 and 2 in a door handle assembly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. With reference to the figures, a variable shear line lock cylinder 10 is provided and includes an outer cylinder 12, an inner cylinder 14, a plurality of pin assemblies 16, a lock assembly 18, and actuation mechanism 20. The outer cylinder 12 rotatably receives the inner cylinder 14 while the pin assemblies 16 are disposed therebetween. The pin assemblies 16 are operable to selectively prevent rotation of the inner cylinder 12 relative to the outer cylinder 14 and are positionable relative to the inner and outer cylinders 12, 14 through engagement with the lock assembly 18. In addition, the actuation mechanism 20 interacts with the pin assemblies 16 and is operable to allow rotation of the inner cylinder 12 relative to the outer cylinder 14, as will be discussed further below. The outer cylinder 12 includes a main body 22 formed integrally with a stack 24, as best shown in FIG. 1. The main body 22 has a generally cylindrical shape having an arcuate outer surface 26 extending between first and second ends 28, 30, and further includes a bore 32 extending along a longitudinal axis 34. The bore 32 forms an inner surface 36 of the main body 22 and is operable to rotatably receive the inner cylinder 14, as best shown in FIG. 2. The stack 24 is disposed on a generally planer surface 38 of the main body 22 and includes two planar sidewalls 40 and a top surface 42. A plurality of bores 44 extend between the stack 24 and main body 22 such that each bore 44 includes a closed end 46 proximate the top surface 42 and an open end 48 proximate the main body 22 and open to the bore 32, as best shown in FIG. 2. Specifically, the open ends 48 extend into bore 32 of the main body 22 and are each operable to receive a pin assembly 16, as will be discussed further below. The inner cylinder 14 is rotatably received by the bore 44 of the outer cylinder 12 and includes a central bore 50, an arcuate outer surface 52, and an axis of rotation 54. The axis of rotation 54 of the inner cylinder 14 is formed generally coaxially with the longitudinal axis 34 of the outer cylinder 12, such that the inner cylinder 12 is received generally at a central point of the bore 44. In this manner, a recess 56 is formed between the outer surface 52 of the inner cylinder 14 and the inner surface 36 of the outer cylinder 12, as best shown in FIG. 3. The inner cylinder 14 further includes a plurality of pin bores 58, a shoulder 60, a spring seat 62, and a shelf portion 64 formed by a bore 66. The pin bores 58 extend from the outer surface 52 of the inner cylinder 14 and terminate at the central bore 50. Each pin bore 58 is aligned with a respective bore 44 of the stack 24 for receiving a pin assembly 16 therebetween. The shoulder 60 is disposed on the outer surface 52 of the inner cylinder 14, proximate the pin bores 58, and includes a cam surface 61 having an engagement face 63. The spring seat 62 is a generally cylindrical member extending into the central bore 50 of the inner cylinder 14 and receives a lower spring 68. The bore 66 extends into the central bore 50, and further serves to form the shelf 64, as best shown in FIG. 3. The shelf 64 extends the length of the bore 66 and includes a reaction surface 70 for interaction with the pin assembly 16. As previously discussed, the lock cylinder 10 includes a plurality of pin assemblies 16. Each pin assembly 16 includes an upper shear cylinder 72, a lower shear cylinder 74, an upper pin 76, a lower pin 78, and an upper spring 80. As each pin assembly 16 is virtually identical, a detailed description of each individual assembly is foregone. The upper shear cylinder 72 includes an outer diameter having a generally cylindrical shape and an arcuate surface 82. The upper shear cylinder 72 further includes a bore 84, a wall 86, and an end cap 90. The bore 84 extends from a closed end 92 to an open end 94, whereby the open end 94 is disposed proximate the recess 56, as best shown in FIG. 3. The wall 86 includes a lock bore 96 for interaction with the lock assembly 18 and an actuation bore 98 for interaction with the actuation assembly 20, as will be discussed further below. The actuation bore 98 further includes a support collar 97 integrally formed with the upper shear cylinder 72 to reinforce the junction between the actuation bore 98 and the wall 86. In addition, the wall 86 includes an annular tab 100 formed on an inner surface of the wall 86, disposed proximate the open end 94, for interaction with the upper and lower pins 76, 78, as best shown in FIG. 4. The upper pin 76 is slidably received by the bore 84 of the upper shear cylinder 72 and includes an annular shoulder 102 and an annular groove 104. In addition, the upper pin 76 includes an engagement bore 106 formed through the upper pin 76, whereby the engagement bore 106 is operable to align with both the lock bore 96 and the actuation bore 98, as will be discussed further below. The upper spring 80 is disposed between the shoulder 102 and the closed end 92 of the upper shear cylinder 72 and is operable to bias the upper pin 76 toward the open end 94 of the upper shear cylinder 72. The lower shear cylinder 74 is substantially similar to the upper shear cylinder 72 and is coaxially aligned therewith. The lower shear cylinder 74 includes an outer diameter having a generally cylindrical shape and an arcuate surface 108. The lower shear cylinder 74 further includes a bore 110 and a wall 112 extending the length of the lower shear cylinder 74. The bore 110 extends from an upper open end 114 to a lower open end 116, whereby the upper open end 114 is disposed proximate the recess 56 and the lower open end 116 is disposed proximate the spring seat 62, as best shown in FIG. 3. The wall 112 includes a lock bore 118 for interaction with the lock assembly 18 and an actuation bore 120 for interaction with the actuation assembly 20. The actuation bore 120 further includes a support collar 121 integrally formed with the lower shear cylinder 74 to reinforce the junction between the actuation bore 120 and the wall 112. In addition, the wall 112 includes an annular tab 122 formed on an inner surface of the wall 112 disposed between the upper and lower open ends 114, 116, generally proximate the lock and actuation bores 118, 120, as best shown in FIG. 5. The lower pin 78 is slidably received by the bore 110 of the lower shear cylinder 74 and includes an annular shoulder 124, an annular groove 126, and an engagement bore 128 formed through the lower pin 78. The engagement bore 128 is operable to align with both the lock bore 118 and the actuation bore 120, as will be discussed further below. In addition, a pin spring 130 annularly surrounds the lower pin 78 to bias the lower pin 78 in a direction generally away from the recess 56 and toward the lower open end 116. The pin spring 130 engages the annular tab 122 at a first end and engages the annular shoulder 124 of the lower pin 78 at a second end. In this manner, the pin spring 130 is operable to bias the lower pin 78 relative to the lower shear cylinder 74, generally toward the lower open end 116. In addition, the lower pin 78 includes an engagement surface 132 formed proximate the annular shoulder 124, as best shown in FIG. 3. The engagement surface 132 opposes the spring seat 62 such that a key recess 134 is formed therebetween. As previously discussed, the lower shear cylinder 74 is co-axially aligned with the upper shear cylinder 72. In this manner, the bore 84 of the upper shear cylinder 72 is aligned with the bore 110 of the lower shear cylinder 74 and defines a first shear zone 141 between the open end 94 of the upper shear cylinder 72 and the upper open end 114 of the lower shear cylinder 74. Additionally, a second shear zone 143 is defined between the upper pin 76 and lower pin 78, whereby the second shear zone 143 is operable to move relative to the upper and lower shear cylinders 72, 74, as will be discussed further below. The lock assembly 18 is operable to fixedly hold the upper and lower shear cylinders 72, 74 relative to the outer and inner cylinders 12, 14. The lock assembly 18 includes an upper lock rack 136, a lower lock rack 138, an upper lock pin 140, and a lower lock pin 142. The upper lock rack 136 is fixed to the outer cylinder 18 and includes a plurality of locking recesses 144 while the lower lock rack 138 similarly includes a plurality of locking recesses 146 and is fixedly attached to the inner cylinder 14. The upper lock pin 136 is an elongate cylindrical member and is operable to be slidably received by the lock bore 96, formed in the upper shear cylinder 72. In addition, the upper lock pin 136 includes a lock post 148 integrally formed therewith for interaction with the upper lock rack 136. Specifically, the lock post 148 is formed generally perpendicular to the upper lock pin 136 and is operable to matingly engage the locking recesses 144 formed in the upper lock rack 136 as the lock pin 136 translates within the lock bore 96. The lower lock pin 138 is an elongate cylindrical member and is operable to be slidably received by the lock bore 118, formed in the lower shear cylinder 74. In addition, the lower lock pin 138 includes a lock post 150 integrally formed therewith for interaction with the lower lock rack 138. Specifically, the lock post 150 is formed generally perpendicular to the lower lock pin 138 and is operable to matingly engage the locking recesses 146 formed in the lower lock rack 138 as the lock pin 138 translates within the lock bore 118. The actuation assembly 20 is operable to fix the upper and lower pins 76, 78 relative to the upper and lower shear cylinders 72, 74, respectively, when the inner cylinder 14 is rotated relative to the outer cylinder 12. Specifically, the actuation assembly 20 includes an upper assembly 152 operable to selectively fix the upper pin 76 to the upper shear cylinder 72 and a lower assembly 154 operable to selectively fix the lower pin 78 relative to the lower shear cylinder 74. The upper assembly 152 includes a cam 156, an upper actuation pin 158, and an upper spring 160, as best shown in FIG. 4. The cam 156 is rotatably supported by the outer cylinder 12 and includes a main body 162 and a flange 164 extending from the main body 162. The main body 162 includes an outer surface 166 having a pin engagement surface 168 operable to translate the actuation pin 158 in response to movement of the inner cylinder 14. The flange 164 extends from the main body 162 and includes a cylinder engagement surface 170 operable to engage the inner cylinder 14 when the inner cylinder 14 rotates relative to the outer cylinder 12. The upper actuation pin 158 includes a generally L-shape having a first leg 172 slidably received by the actuation bore 98 of the upper shear cylinder 72 and a second leg 174 formed generally perpendicular to the first leg 172. The second leg 174 includes a reaction surface 176, whereby the reaction surface 176 abuts the pin engagement surface 168 of the cam 156, as best shown in FIG. 5. The overall length of the reaction surface 176 is governed by the overall length of the upper lock rack 136 to ensure that the reaction surface 176 maintains constant engagement with the pin engagement surface 168 of the cam 156 as the upper shear cylinder 72 is moved relative to the upper lock rack 136 through the plurality of locking recesses 144. The upper spring 160 is disposed between the upper shear cylinder 72 and the second leg 174 of the actuation pin 158, as best shown in FIGS. 3 and 4. The spring 160 biases the actuation pin 158 toward the cam 156, and out of engagement with the upper pin 76. In this manner, a sufficient force must be applied to the second leg 174 of the actuation pin 158 to over come the bias of the upper spring 160 for the first leg 172 of the actuation pin 158 to translate within the actuation bore 98 of the upper shear cylinder 72 and engage the upper pin 76. The lower assembly 154 includes a cam 176, a lower actuation pin 178, and a lower spring 180, as best shown in FIG. 5. The cam 176 is slidably supported by the inner cylinder 14 and includes a main body 182 and a recess 184. The main body 182 includes an outer surface 186 having a cam surface 188 operable to engage the inner surface 36 of the outer cylinder 12 to translate the actuation pin 178 in response to rotation of the inner cylinder 14 relative to the outer cylinder 12. The recess 184 is formed between upper and lower flanges 185, 187 of the main body 162 and includes an engagement surface 190 operable to engage the lower actuation pin 178. The lower actuation pin 178 includes a generally L-shape having a first leg 192 slidably received by the actuation bore 120 of the lower shear cylinder 74 and a second leg 194 formed generally perpendicular to the first leg 192, as best shown in FIG. 5. The second leg 194 includes a reaction surface 196, which abuts the pin engagement surface 190 of the recess 184. The length of the recess 184, generally defined between the upper and lower flanges 185, 187, is governed by the overall length of the lower lock rack 138. Specifically, the length of the recess 184 is designed to ensure that the reaction surface 196 maintains constant engagement with the engagement surface 190 of the cam 176 as the lower shear cylinder 74 is moved relative to the lower lock rack 138 through the various locking recesses 146 disposed on the lower lock rack 138. The lower spring 180 is disposed between the lower shear cylinder 74 and the second leg 194 of the actuation pin 178, as best shown in FIGS. 3 and 5. The spring 180 biases the actuation pin 178 toward the cam 176 and out of engagement with the lower pin 78. In this manner, a sufficient force must be applied to the second leg 194 of the actuation pin 178 to over come the bias of the lower spring 180 for the first leg 192 of the actuation pin 178 to translate within the actuation bore 120 of the lower shear cylinder 74 and engage the lower pin 78. With reference to the figures, the operation of the lock cylinder 10 will be described in detail. The lock cylinder 10 is shown incorporated into a door assembly 200 having a door 202, a handle 204, and a latch bolt 206, as shown in FIG. 10. The lock cylinder 10 is operable to permit or restrict rotation of the handle 204 relative to the door 202 to selectively lock the door 202 relative to a doorframe 208. Specifically, as the door handle 204 is permitted to rotate, the latch bolt 206 may be selectively retracted from engagement with a latch plate 210 disposed on the doorframe 208. As can be appreciated, as the latch bolt 206 is retracted from engagement with the latch plate 210, the door 202 is permitted to rotate relative to the door frame 208 and when the latch bolt 206 is extended, and engaged with the latch plate 208, the door is restricted from rotating relative to the door frame 208. In this regard, the lock cylinder 10 is operable to selectively permit or restrict rotation of the door 202 relative to the doorframe 208 by selectively permitting and restricting rotation of the door handle 204. To selectively lock and unlock the lock cylinder 10, a key 212 is provided and includes a plurality of raised engagement surfaces 214 and a flat or planar surface 216 formed on an opposite side of the key 212 from the raised surfaces 214. To unlock the lock cylinder 10, and permit rotation of the door handle 204, the key 212 is inserted into a key hole 218 formed in the first end 28 of the outer cylinder 12. In this manner, the key 212 is received by the key recess 134 of the lower shear cylinder 74 and contacts the engagement surface 132 of the lower pin 78, as best shown in FIG. 6. Specifically, each raised surface 214 of the key 212 contacts a respective engagement surface 132 of a respective pin assembly 16 while the planar surface 216 contacts the reaction surface 70 of the spring seat 62, as best shown in FIG. 2. Provided the correct key 212 is inserted into the key recess 134, each raised surface 214 is operable to engage each lower pin 78 to thereby raise the lower pin 78 relative to the lower shear cylinder 74 and raise the upper pin 76 relative to the upper shear cylinder 72. Once the upper and lower pins 76, 78 are sufficiently raised relative to the upper and lower shear cylinders 72, 74, the second shear zone 143 will clear the upper open end 114 of the lower shear cylinder 74 and align with the first shear zone 141 to permit rotation of the inner cylinder 14 relative to the outer cylinder 12. As can be appreciated, each of the raised surfaces 214 are of varying height and will thus raise each independent lower pin 78 a different amount relative to the lower shear cylinder 74. Once the correct key 212 is fully inserted into the key recess 134, the inner cylinder 14 is permitted to rotate relative to the outer cylinder 12, as best shown in FIG. 7. To rotate the inner cylinder 14, an external force is applied to the inner cylinder 14 via door handle 204. Upon receiving a sufficient force, the inner cylinder 14 will rotate relative to the outer cylinder 12, thereby causing the flange 164 of the cam 156 to engage the shoulder 60 of the inner cylinder 14. Engagement between the flange 164 and the shoulder 60 of the inner cylinder 14 causes the cam 156 to rotate, thereby causing the pin engagement surface 168 to contact the second leg 174 of the actuation pin 158 and compress the upper spring 160. Once the upper spring 160 is sufficiently compressed, the first leg 172 of the actuation pin 158 will translate within the actuation bore 98 of the upper shear cylinder 72 and engage the engagement bore 106 of the upper pin 76. In this regard, the upper pin 76 is locked in a fixed position relative to the upper shear cylinder 72 to prevent the upper spring 160 from biasing the upper pin 76 out of engagement with the upper shear cylinder 72. As can be appreciated, without the lower pin 78 to hold the upper in 76 within the upper shear cylinder 72, the upper spring 160 would cause the upper pin 76 to be released from the upper shear cylinder 72 at the open end 94. Similarly, upon sufficient rotation of the inner cylinder 14, the cam 176 of the lower actuation assembly 154 will engage the inner surface 36 of the outer cylinder 12, thereby causing the cam 176 to translate on the shelf portion 64. Sufficient translation of the cam 176 will cause the second leg 194 of the lower actuation pin 178 to engage the engagement surface 190 of the recess 184 and cause the pin 178 to move against the bias of the lower spring 180. Once the pin 178 sufficiently compresses the spring 180, the pin 178 will translate within the actuation bore 120 of the lower shear cylinder 74 and engage the engagement bore 128 of the lower pin 78, thereby locking the lower pin 78 relative to the lower shear cylinder 74. In this regard, the lower pin 78 is locked in a fixed position relative to the lower shear cylinder 74 to prevent the pin spring 130 from biasing the lower pin 78 out of engagement with the lower shear cylinder 74. As can be appreciated, without the upper pin 76 to hold the lower pin 78 within the lower shear cylinder 74, the pin spring 130 would cause the lower pin 78 to be released from the lower shear cylinder 74 at the upper open end 114. In the event that the incorrect key is inserted into the key recess 134, the raised portions of the key will not properly align first shear zone 141 with the second shear zone 143, and will thereby not unlock the lock cylinder 10. Specifically, as the raised portions of the key contact the lower pins 78, the upper and lower pins 76, 78 will be raised relative to the upper and lower shear cylinders 72, 74, but will not be raised to a point at which the first shear zone 141 aligns with the second shear zone 143 to permit rotation of the inner cylinder 14 relative to the outer cylinder 12. If the incorrect key is inserted into the key recess 134, the second shear zone 143 will either be disposed below the first shear zone 141 as shown in FIG. 3, or will be pushed into a region within the upper shear cylinder 72, generally above the first shear zone 141. In either event, the inner cylinder 14 will not be permitted to rotate relative to the outer shear cylinder 12 as the first and second shear zones 141, 143 are not properly aligned. As can be appreciated, if the first and second shear zones 141, 143 are not properly aligned, the upper and lower pins 76, 78 will interfere with the upper and lower shear cylinders 72, 74, thereby prohibiting rotation of the inner cylinder 14 relative to the outer cylinder 12. As the first shear zone 141 must be properly aligned with the second shear zone 143 to permit rotation of the inner cylinder 14 relative to the outer cylinder 12, it is also important to position the first shear zone 141 such that the first shear zone 141 is disposed within the recess 56 between the inner and outer cylinders 14, 12 to prevent interference between the upper and lower shear cylinders 72, 74 and the inner surface 36 of the outer cylinder 12. To ensure that the first shear zone 141 is disposed within the recess 56, the lock assembly 18 serves to fix the upper and lower shear cylinders 72, 74 relative to the inner and outer cylinders 14, 12 such that the first shear zone 141 is disposed within the recess 56. The upper and lower shear cylinders 72, 74 are fixed relative to the outer and inner cylinders 12, 14 through a reset or re-keying operation. To re-key the lock cylinder 10, the correct key 212 is inserted into the key recess 134 to properly align the first and second shear zones 141, 143 and position the lock cylinder 10 in the unlocked condition. Once the first and second shear zones 141, 143 are properly aligned, the upper lock pin 140 is disengaged from the upper lock rack 136 using a pin tool (not shown) and the lower lock pin 142 is disengaged from the lower lock rack 138 using a pin tool (not shown), as best shown in FIG. 8. The pin tools engage the respective upper and lower lock pins 140, 142 to selectively move the pins 140, 142 into, and out of, engagement with the upper and lower lock racks 136, 138. As the upper lock pin 140 disengages the upper lock rack 136, the upper lock pin 140 translates within the upper lock bore 96 of the upper shear cylinder 72 and engages the engagement bore 106 of the upper pin 76. In addition, as the lower lock pin 142 disengages the lower lock rack 138, the lower lock pin 142 translates within the lower lock bore 118 of the lower pin 78. In this manner, the upper and lower pins 76, 78 are fixed for movement with the upper and lower shear cylinders 72, 74 and the first and second shear zones 141, 143 are fixed in alignment relative to one another. Once the upper and lower pins 76, 78 are fixed to the upper and lower shear cylinders 72, 74, respectively, and the lock pins 140, 142 are disengaged from the lock racks 136, 138, the key 212 may be removed. Removal of the key 212 will cause the pin assembly 16 to be biased into a reset position by a spring 220 acting on the top surface 42 of the upper shear cylinder 72, as best shown in FIG. 8. In this condition, the lock cylinder 10 is in a learn or reset mode, having the lower shear cylinder 74 positioned such that the engagement surface 132 of the lower pin 78 is proximate the spring seat 62. Once the pin assembly 16 is in the reset or learn mode, a new key 222 may be inserted into the key recess 134 of the lower shear cylinder 74. As the new key 222 is inserted, the raised portions 224 of the key 222 will caused the lower pins 78 of the respective pin assemblies 16 to raise both the lower shear cylinder 74 and lower pin 78 as well as the upper shear cylinder 72 and upper pin 76 relative to the outer and inner cylinders 12, 14, as best shown in FIG. 9. As the upper pin 76 is locked relative to the upper shear cylinder 72 and the lower pin 78 is locked relative to the lower shear cylinder 74, the aligned first and second shear zones 141, 143 will also be concurrently raised and re-positioned within recess 56 between the outer and inner cylinders 12, 14. The position of each shear zone 141, 143 relative to the outer and inner cylinders 12, 14 is determined by the overall height of the particular raised surface 224 of the new key 222 acting on the respective lower pin 78. As can be appreciated, taller raised portions of the new key 222 will position the shear zones 141, 143 generally closer to the inner surface 36 of the outer cylinder 12 while shorter raised portions of the new key 222 will position the shear zones 141, 143 closer to the outer surface 52 of the inner cylinder 14. Once the new key 222 is inserted into the key recess 134, the lock pins 140, 142 are disengaged from the upper and lower pins 76, 78 and re-engage with the respective upper and lower lock racks 136, 138 to fixedly position the upper shear cylinder 73 relative to the outer cylinder 12 and fixedly position the lower shear cylinder 74 relative to the inner cylinder 14. Once the upper lock pin 140 is received by a locking recess 144 of the upper lock rack 136 and the lower lock pin 142 is received by a locking recess 146 of the lower lock rack 138, the new key 222 may be removed. At this point, the new key 222 will be operable to lock and unlock the lock cylinder 10 while the old key 212 will no longer function to do so. As each raised portion 224 of the new key 222 includes a different height than the next, the shear lines 141, 143 will be positioned within the recess 56 in varying positions such that an overall shear line of the lock cylinder 10 will vary between each pin assembly 16. Such variation between pin assemblies 16 provides the lock cylinder 10 with the capability of being re-keyed without having to replace each individual upper and lower pin 76, 78. In addition, this relationship allows each of the upper pins 76 to be of the same size and allows each of the lower pins 78 to also be of the same size, thereby obviating the need for a plurality of different pins to re-key the lock cylinder 10. The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>It is well known in the art to provide a door hardware assembly that is operable to maintain a door in a closed position by selectively securing the door to a doorframe. It is equally well known to provide a door hardware assembly that is capable of being locked to selectively prevent operation of the door hardware assembly. As can be appreciated, by preventing operation of the door hardware assembly, the door will remain closed and in a locked condition. Such conventional door hardware assemblies generally include a handle assembly, lock cylinder, and key, whereby the key is operable to selectively lock the lock cylinder to prevent operation of the door handle assembly and maintain the door in the closed and locked condition. Conventional door hardware assemblies are typically disposed on a door proximate to an edge of the door for selective engagement with a striker assembly mounted on a door frame. As previously discussed, door hardware assemblies commonly include a handle assembly, lock cylinder, and key. The lock cylinder is designed to matingly receive a key, whereby the key is operable to toggle the lock cylinder between a locked and unlocked condition. The unlocked condition of the lock cylinder permits rotation of the handle assembly and, thus, movement of the door relative the doorframe. The locked condition prohibits rotation of the handle assembly, thereby maintaining the door in a closed and locked condition. As can be appreciated, the key is specific to the particular lock cylinder so as to prevent unwanted operation of the door handle assembly and movement of the door relative the doorframe. In this regard, a lost or stolen key may provide unwanted operation of the lock cylinder and unwanted access through the door. For at least this reason, being able to “reset” or “re-key” the lock cylinder, without having to replace the entire mechanism, is a desirable feature. In this regard, conventional door hardware assemblies commonly provide for adjustment of a locking mechanism disposed within the lock cylinder. Re-keying of a conventional lock cylinder provides the lock cylinder with a new key that is operable to lock and unlock the re-configured lock cylinder, while concurrently prohibiting further use of the lost key. Such lock cylinders commonly include a plurality of pin assemblies, whereby each pin assembly includes an upper pin slidably disposed within an upper shear cylinder and a lower pin slidably disposed within a lower shear cylinder. The upper and lower shear cylinders are axially aligned such that a first shear zone is formed between the upper and lower pins and a second shear zone is formed between the upper and lower shear cylinders. As previously discussed, a key is used to selectively lock and unlock the lock cylinder, whereby raised portions disposed on the key are operable to engage the upper and lower pins to properly align the second shear zone with the first shear zone. Proper alignment of the first and second shear zones allows each pin to disengage the respective shear cylinder and permit rotation of the door handle assembly. In a re-keying operation, the upper and lower pins are adjusted to vary the relative heights of each of the upper and lower pins. In this regard, a new key having raised portions commensurate with the new pin heights of each pin assembly, is required to properly align the first and second shear zones of the upper and lower pins. Once the new pins are installed, the lock cylinder will no longer permit rotation of the door handle assembly if the old key is used in the lock cylinder. As can be appreciated, the old key is not commensurate with the new pin heights and therefore will not properly align the first and second shear zones of the respective pin assemblies. While conventional lock cylinders adequately provide for a re-keying operation of a lock cylinder, they suffer from the disadvantage of requiring partial disassembly of the lock cylinder and typically require a specialized technician, such as a locksmith, to perform the re-keying operation. Further, conventional lock cylinders suffer from the disadvantage of requiring various pin heights and combinations thereof to properly re-key the cylinder. Further yet, conventional re-keying kits require door hardware manufacturers to produce varying pin heights for each kit, thereby overproducing the required number of individual pins to simply re-key one lock cylinder. Therefore, a lock cylinder that provides for a re-keying operation without requiring disassembly of the lock cylinder is desirable in the industry. Furthermore, a lock cylinder that is capable of being re-keyed without replacing the existing components is also desirable. Further yet, a lock cylinder that provides for a re-keying operation without requiring a plurality of additional pins with varying pin heights is also desirable. | <SOH> SUMMARY OF THE INVENTION <EOH>Accordingly, the present invention provides a lock cylinder including an outer cylinder having a first bore formed along a first longitudinal axis, an inner cylinder rotatably disposed within the first bore, and a pin assembly disposed within the inner and outer cylinders. The pin assembly is operable to selectively lock the inner cylinder relative to the outer cylinder. The pin assembly includes an upper shear cylinder positionable relative to the outer cylinder and a lower shear cylinder positionable relative to the inner cylinder, whereby the upper and lower shear cylinders are movable to define a first shear line therebetween. In addition, the pin assembly includes an upper pin slidable within the upper shear cylinder and a lower pin slidable within the lower shear cylinder, whereby the upper and lower pins define a second shear line therebetween. The lock cylinder is positionable from a locked position to an unlocked position when the first shear line is aligned with the second shear line. In addition, upper and lower lock racks are provided to lock the upper and lower shear cylinders relative to the inner and outer cylinders. Specifically, the upper lock rack is operable to lock the upper shear cylinder relative to the outer cylinder while the lower lock rack is operable to lock the lower shear cylinder relative to the inner cylinder. In this regard, the upper and lower lock racks are operable to position the first shear line in one of a plurality of positions relative to the inner and outer cylinders to vary the position of the first shear line during a re-keying operation. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. | 20040401 | 20070116 | 20051006 | 78406.0 | 0 | GALL, LLOYD A | VARIABLE SHEAR LINE LOCK CYLINDER | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,282 | ACCEPTED | Extrusion laminate polymeric film article and gastric occlusive device comprising same | A multilayer film including a layer of sealing film, having main top and bottom surfaces, and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces. The sealing film has a composition and thickness imparting gas barrier character to the multilayer film, of which the layer(s) of thermoplastic polymer film by themselves lack such gas barrier character. Such multilayer film is usefully employed to form biologically compatible therapeutic articles such as medical balloons that are constructed to be inflated in vivo. | 1. A multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character. 2. The multilayer film of claim 1, wherein the thermoplastic polymer film comprises a thermoplastic polymer selected from the group consisting of polyurethane elastomers, polyester ether elastomers, polyamide elastomers, polyamides, styrenic elastomers, polyvinylchloride, polyvinylethers, ethylene vinyl acetate, polyethylene, polyethylene copolymers, polypropylene copolymers, and combinations of two or more of the foregoing, and wherein when the multilayer film comprises more than one layer of thermoplastic polymer film, each of such layers may be compositionally the same as or different from other layers of thermoplastic polymeric material. 3. The multilayer film of claim 1, wherein the sealing film comprises a material selected from the group consisting of polyvinylidene chloride (PVDC), polyvinylidene bromide, and ethylene vinyl alcohol polymers. 4. The multilayer film of claim 1, wherein the thermoplastic polymer film comprises a thermoplastic polymer selected from the group consisting of polyurethane and polyurethane co-polymers. 5. The multilayer film of claim 1, wherein the sealing film comprises a material selected from the group consisting of polyvinylidene chloride and EVOH. 6. The multilayer film of claim 1, wherein the sealing film comprises polyvinylidene chloride. 7. The multilayer film of claim 1, having a thickness in a range of from about 0.5 to about 50 mils (0.0127 mm to 1.27 mm). 8. The multilayer film of claim 1, having a thickness in a range of from about 0.5 to about 10 mils (0.0127 mm to 0.254 mm). 9. The multilayer film of claim 1, having a thickness in a range of from about 2 mils to about 6 mils (0.0508 mm to 0.1524 mm). 10. The multilayer film of claim 1, wherein the thickness of the sealing film is in a range of from about 0.2 mil to about 6 mil (0.00508 mm to 0.1524 mm). 11. The multilayer film of claim 1, wherein the thermoplastic polymer film has a thickness in a range of from about 2.0 mils to about 20.0 mils (0.0508 mm to 0.508 mm). 12. The multilayer film of claim 1, comprising a sealing film of polyvinylidene chloride, having a thickness in a range of from about 0.25 to about 2.0 mil (0.00635 mm to 0.0508 mm), to which a polyurethane elastomer film, having a thickness in a range of from about 2.0 mils to about 5.0 mils (0.0508 mm to 0.127 mm), is extrusion bonded. 13. The multilayer film of claim 1, bonded to a second such film. 14. The multilayer film of claim 13, wherein the bonded multilayer film and film bonded thereto form a gas-retentive enclosure. 15. A gas-retentive enclosure comprising a multilayer film, wherein said multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character. 16. The gas-retentive enclosure of claim 15, further comprising a means for introducing gas into an interior volume of the gas-retentive enclosure. 17. The gas-retentive enclosure of claim 16, further comprising a means for releasing gas from the interior volume of the gas-retentive enclosure. 18. The gas-retentive enclosure of claim 15, wherein gas retained in said enclosure comprises water vapor. 19. The gas-retentive enclosure of claim 15, wherein gas retained in said enclosure comprises carbon dioxide. 20. A gastric occlusive device, comprising: a balloon formed of a multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character.; and an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. 21. The gastric occlusive device of claim 20, wherein the thermoplastic polymer film comprises a thermoplastic polymer selected from the group consisting of polyurethane elastomers, polyester ether elastomers, polyamide elastomers, polyamides, styrenic elastomers, polyvinylchloride, polyvinylethers, ethylene vinyl acetate, polyethylene, polyethylene copolymers, polypropylene copolymers, and combinations of two or more of the foregoing, and wherein when the multilayer film comprises more than one layer of thermoplastic polymer film, each of such layers may be compositionally the same as or different from other layers of thermoplastic polymeric material. 22. The gastric occlusive device of claim 20, wherein the sealing film comprises a material selected from the group consisting of polyvinylidene chloride (PVDC), polyvinylidene bromide, and ethylene vinyl alcohol polymers. 23. The gastric occlusive device of claim 20, wherein the thermoplastic polymer film comprises a thermoplastic polymer selected from the group consisting of polyurethane and polyurethane co-polymers. 24. The gastric occlusive device of claim 20, wherein the sealing film comprises a material selected from the group consisting of polyvinylidene chloride and EVOH. 25. The gastric occlusive device of claim 20, wherein the thermoplastic polymer film is formed of polyurethane or a polyurethane co-polymer. 26. The gastric occlusive device of claim 20, wherein the sealing film comprises polyvinylidene chloride. 27. The gastric occlusive device of claim 20, wherein the multilayer film has a thickness in a range of from about 0.5 to about 50 mils (0.0127 mm to 1.27 mm). 28. The gastric occlusive device of claim 20, wherein the multilayer film has a thickness in a range of from about 0.5 to about 10 mils (0.0127 mm to 0.254 mm). 29. The gastric occlusive device of claim 20, wherein the multilayer film has a thickness in a range of from about 2 mils to about 6 mils (0.0508 mm to 0.1524 mm). 30. The gastric occlusive device of claim 20, wherein the thickness of the sealing film is in a range of from about 0.2 mil to about 6 mil (0.00508 mm to 0.1524 mm). 31. The gastric occlusive device of claim 20, wherein the thermoplastic polymer film has a thickness in a range of from about 2.0 mils to about 20.0 mils (0.0508 mm to 0.508 mm). 32. The gastric occlusive device of claim 20, comprising a sealing film of polyvinylidene chloride, having a thickness in a range of from about 0.25 to about 2.0 mil (0.00635 mm to 0.0508 mm), to which a polyurethane elastomer film, having a thickness in a range of from about 2.0 mils to about 5.0 mils (0.0508 mm to 0.127 mm), is extrusion bonded. 33. The gastric occlusive device of claim 20, wherein two pieces of multilayer film are bonded to one another. 34. The gastric occlusive device of claim 20, wherein two half-sections of multilayer film are thermoformed, and then bonded to one another. 35. The gastric occlusive device of claim 20, wherein two pieces of multilayer film are bonded circumferentially to one another to form a 360° seal having a seam devoid of any neck or opening therein. 36. A method of therapeutic intervention for treatment of a patient in need of such treatment, said method comprising: introducing to a physiological locus of a patient in need of such therapeutic intervention a balloon formed of a multilayer film, wherein said multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, on at least one of the main top and bottom surfaces of the sealing film; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character; with an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. 37. The method of claim 36, wherein said balloon comprises two pieces of said multilayer film bonded to one another. 38. The method of claim 36, wherein said balloon comprises two half-sections of multilayer film that are thermoformed, and then bonded to one another. 39. The method of claim 36, wherein said balloon comprises two pieces of multilayer film that are bonded circumferentially to one another to form a 360° seal having a seam devoid of any neck or opening therein. 40. The method of claim 36, further comprising contacting the effervescent material with liquid reactive therewith to liberate gas for inflation of the balloon at said physiological locus. | BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an extrusion laminate film, and to products formed therefrom having a gas barrier character. In a specific embodiment, the invention relates to a gastric occlusive device fabricated using such film. 2. Description of the Related Art In the field of polymeric film technology, involving polymeric sheet stock or web-form material, typically having a thickness of less than about 25 mils, there is a need for gas-barrier films. Such gas barrier films may be employed for containment of a specific gas when used to form gas receptacles, or as a packaging, cushioning or preservative structure (e.g., when fabricated to contain gas species such as oxygen, nitrogen, argon, helium, carbon dioxide, water vapor, etc). Still other applications relate to the prevention or reduction of gas passage through the film, such as in instances in which any significant penetration of gas through the film may adversely impact an article, structure, material or region that is isolated from an adverse gas environment by the gas barrier film. In the aforementioned applications, the film material may be susceptible to forces and consequent stresses that cause failure of the film, e.g., by cracking, tearing, splitting, stress-softening, embrittlement or other material failure mechanisms. Specific applications of such gas barrier films may include the requirement of biocompatibility, in which the gas barrier film is required to function in or in connection with a physiological environment, whereby the film may be subjected to exposure to biological fluids, variations of temperature, pressure and pH, etc. There is presently a compelling need in the art for readily manufacturable, soft and supple yet durable and reliable gas barrier films for manufacture of medical devices as well as a wide variety of other product articles. SUMMARY OF THE INVENTION The present invention relates to a gas barrier film, as well as to articles and devices incorporating such gas barrier film. In one aspect, the invention relates to a multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymeric material alone lacks such gas barrier character. In such multilayer film, the thermoplastic polymer film is appropriately selected for the specific barrier service to be accommodated by the multilayer film. In a preferred embodiment, wherein the multilayer film is employed as a structural component of a medical device, the thermoplastic polymer film is selected to exhibit biocompatibility, softness to the touch and good weldability (for film welding by welding techniques such as RF impulse welding, hot bar adhesive welding, ultrasonic welding, etc.). In another aspect, the invention relates to a gas-retentive enclosure comprising a multilayer film, wherein the multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character In another aspect, the invention relates to a gastric occlusive device, comprising: a balloon formed of a multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; a layer of thermoplastic polymer film, on at least one of the main top and bottom surfaces of the layer of sealing film; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymeric material alone lacks such gas barrier character; and an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. A still further aspect of the invention relates to a method of therapeutic intervention for treatment of a patient in need of such treatment, such method comprising: introducing to a physiological locus of a patient in need of such therapeutic intervention a balloon formed of a multilayer film, wherein the multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character; with an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. As used herein, the term “film” means a material in a sheet or web form, having a thickness of 50 mils (1.270 mm) or less. As used herein, the term “extrusion laminated” in reference to a film of thermoplastic material means that such film of thermoplastic material is deposited as an extruded melt film on (one or both sides of) the sealing layer film, so that the respective thermoplastic material and sealing layer films are consolidated with one another under elevated temperature conditions. The laminate preferably is formed under process conditions producing substantially uniform thickness of the multilayer film, with a thickness variation across the laminated film desirably being less than 20% and more preferably being less than 15% of the total thickness of the laminate. Other aspects, features and embodiments will be more fully apparent from the ensuing disclosure and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a gas barrier film according to one embodiment of the invention. FIG. 2 is a front elevation view of a gastric occlusive device, according to one embodiment of the invention. FIG. 3 is a schematic front elevation cross-sectional view of a vacuum thermoforming die for use in forming a balloon article for fabrication of a gastric occlusive device of the type shown in FIG. 2. FIG. 4 is a schematic cross-sectional elevation view of a radio frequency (RF) welding operation by which two vacuum thermoformed half-sections formed in the assembly of FIG. 3 after being mated with one another for consolidation at an edge seam, are welded under heat and pressure conditions effecting bonding of the half-sections to one another. DETAILED DESCRIPTION OF THE INVENTION, AND PREFERED EMBODIMENTS THEREOF The present invention is based on the discovery of a laminated multilayer film structure having utility as a gas barrier film, as useful in the fabrication of a wide variety of end-use articles, including, without limitation, gastric occlusion devices. Thus, while the invention is described more fully hereinafter with reference to an illustrative gastric occlusive device, as fabricated from the laminated multilayer film of the invention, it will be appreciated that the inventive film is susceptible of a wide variety of usages, e.g., in applications in which the film must contain a gas at pressure at least equal to pressure of an ambient environment of the article incorporating such film, or in which permeation of gas through the film would adversely affect a structure, article or material on an opposite side of the barrier film from such gas. The gas barrier film structure of the invention is a laminate including: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated (e.g., extrusion laminated) to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymeric material alone lacks such gas barrier character. The disclosure of U.S. patent application Ser. No. 09/977,644 filed Oct. 15, 2001 in the name of Tilak M. Shah for “LOW-PRESSURE MEDICAL BALLOONS AND METHOD OF MAKING SAME,” hereby is incorporated herein in its entirety, for all purposes. As disclosed in such earlier application Ser. No. 09/977,644, a low-pressure medical balloon can be fabricated by providing a thin film of thermoplastic polymeric material that is heated to a sufficient temperature for vacuum forming thereof. A first half-section for the balloon then is formed by subjecting the thermoplastic polymeric film to vacuum suction. A second half-section for the balloon then is formed by subjecting a same or different thermoplastic polymeric thin film to vacuum suction, following which the first half-section of the balloon is bonded to the second half-section along respective edges thereof to yield the balloon. Such methodology may be employed to form a low-pressure balloon article of a non-pillowed, generally spherical or flattened spherical character, in which the respective half-sections of the balloon are readily fabricated and mated to form the product balloon article. The balloon article as thus formed may then be everted (turned inside out) so that the free edges (flange or “skirt”) of the seam are disposed in the interior volume of the balloon. The laminate of the present invention is formed with an outer layer (on one or both sides of the sealing film) of a thermoplastic polymeric film material, such as polyurethane elastomer, polyester ether elastomer, polyamide elastomer, etc., having good physical properties for the intended end-use, but which is gas-permeable to an undesired extent, in respect of its intended end-use application. The thermoplastic polymer film may have any suitable thickness, e.g., a thickness in a range of from about 2.0 mils to about 20 mils (0.0508 mm to 0.508 mm), although greater or lesser thicknesses may be employed in specific applications of the invention, e.g., a thickness in a range of from about 2.0 mils to about 5.0 mils (0.0508 mm to 0.127 mm). The laminate includes a layer of a sealing film. A layer of thermoplastic material is laminated, e.g., extrusion laminated, on at least one of the main top and bottom surfaces of the sealing layer. The sealing film layer has a composition and thickness imparting gas barrier character to the laminated film structure. In other words, the presence of the sealing film effects a diminution of the gas permeability characteristics of the laminate (relative to the gas permeability characteristics of the outer thermoplastic material layer(s) per se), in respect of particular gas components or gas mixtures of interest, so that the resulting multilayer laminate is suitable for use as a gas barrier. Polyurethane elastomer is a preferred material of construction for the outer layer(s) of the laminated film, although a wide variety of other materials, such as polyester ether elastomer, stryenic elastomers, polyamide and polyamide elastomers and other film-forming thermoplastic elastoplastics, incuding the polymeric families of polyethylene, polypropylene, polyvinylchloride (PVC), polyvinylether (PVE), ethylene vinyl acetate (EVA) polymers, and combinations of two or more of the foregoing, etc., may be employed. The choice of a specific thermoplastic material for a given end use application, and the choice of extrusion laminating a layer of such thermoplastic material to only one, or alternatively to both, of the surfaces of the sealing film layer, can readily be made within the skill of the art, and without undue experimentation, based on the disclosure herein. The multilayer laminated film of the present invention is readily processed in the manner described in the aforementioned U.S. patent application Ser. No. 09/977,644, to form balloon and catheter articles of widely varying types. For example, a multilayer extrusion laminated film of the invention may be utilized to form low-pressure balloons and catheters useful for a wide variety of procedures, such as minimally invasive surgery. In medical balloon usage, it is important that the balloon structure have uniform wall thickness and concentric expansion during inflation, so that the physiological effect is correspondingly uniform and able to be well-standardized and quantified. The multilayer extrusion laminated films of the invention are particularly useful in the fabrication of balloon articles such as the gastric occlusive device hereinafter more fully described. In such application, the extrusion laminated film can have a thickness in a range of from about 0.5 to about 10 mils (0.0127 mm to 0.254 mm), and more preferably in a range of from about 2 mils to about 6 mils (0.0508 mm to 0.1524 mm), although greater or lesser thicknesses of the extrusion laminated film may be employed, e.g., a thickness in a range of from 0.5 to about 50 mils (0.0127 mm to 1.27 mm), as appropriate in a specific end-use application. The sealing film layer, on which at least one outer layer of thermoplastic material is laminated in the laminated film of the invention, may be of any suitable type that is effective to impart gas barrier characteristics to the laminate. As indicated, the outer layer can be formed of a material such as a polyurethane elastomer or other suitable thermoplastic elastomer. The sealing layer in relation to specific outer layer thermoplastic materials can be fabricated of any complementary material imparting gas barrier characteristics to the overall laminated film that includes the outer layer(s) and the sealing layer. Illustrative sealing layer materials include polyvinylidene chloride (PVDC), commercially available from Dow Chemical Company under the trademark Saran, polyvinylidene bromide, ethylene vinyl alcohol polymers (conventionally referred to as “EVOH” polymers), etc. The sealing film can be of any suitable thickness as required for the gas barrier end-use application. Typically, when polyvinylidene chloride or EVOH polymers are employed to form the sealing film, the sealing film can have a thickness on the order of from about 0.2 mil to about 6 mil (0.00508 mm to 0.1524 mm). In an illustrative embodiment, the outer layer of the extrusion laminate is formed of a sealing layer of polyvinylidene chloride, having a thickness in a range of from about 0.25 to about 2.0 mil (0.00635 mm to 0.0508 mm), to which a layer of polyurethane elastomer film, having a thickness in a range of from about 2.0 mils to about 5.0 mils (0.0508 mm to 0.127 mm), is extrusion bonded. It will be appreciated that when the multilayer laminate of the invention features two outer layers of thermoplastic polymeric material, each laminated to the sealing layer on a respective surface of the sealing layer, the outer layers of thermoplastic material may be the same as or different from one another in composition. For example, a polyurethane elastomeric film may be extrusion laminated to one face of a polyvinylidene chloride film, and a polyethylene film may be extrusion laminated to the other face of the polyvinylidene chloride film. It will also be appreciated that the thermoplastic material layer may include multiple sub-layers, and that the sealing layer may likewise include multiple sublayers, and that these respective sub-layers may be compositionally homogeneous or alternatively varied in composition along the successive sub-layers. The laminate of the invention may be utilized to form a gastric occlusive device, as hereinafter more fully described. The gastric occlusive device is a balloon that is fabricated to contain a charge of an effervescent material that in the presence of water or moisture reacts to form CO2 gas. The balloon containing such effervescent material charge can be injected, through the multilayer film via a suitable self-healing seal valve therein, with a requisite amount of water or aqueous medium. The injected water or aqueous medium then reacts with the effervescent material, to generate carbon dioxide as an inflation gas for the balloon. The balloon of the gastric occlusive device thus is inflated subsequent to being placed in a gastric locus of a patient. The inflated balloon thereafter remains sufficiently gas-tight in character so that the inflated volume of the balloon is relatively constant over an extended period of time. In one embodiment, the balloon is formed with a degradable seal, which under exposure to a physiological environment degrades to permit deflation of the balloon and removal thereof from a physiological locus. In one preferred dimensional aspect, the gastric occlusive balloon has a diameter when inflated of 3 to 5 inches, although such balloon in the general practice of the invention may have any suitable size and dimensional characteristics appropriate to the use of the balloon in a specific application thereof. In a physiological environment, the balloon article of the invention must withstand pressures associated with such environment, e.g., pressures of 1 to 5 psi. Further, the physiological environment may subject the balloon article to compressive, tensile and torsional forces. Under such conditions in the physiological locus, the multilayer laminate must be resistant to flex-cracking, particularly when such conditions involve repeated cycles of shape-deforming stresses. The selection of film thickness of the laminate is particularly critical in this respect, since excessively thick films are disproportionately more susceptible to flex-cracking, particularly at the seams where adjacent panels or sections of a film are bonded to one another. Thus, the balloon article incorporates a multilayer laminate that has desired characteristics for the intended use application. These characteristics may variously include softness to the touch (e.g., a Shore D hardness of 65 or less), resistance to flex fatigue, and leak-tightness and dimensional stability under the range of pressure conditions that may be encountered in such intended use application. Balloon or other gas-retentive or gas barrier articles in accordance with the invention can alternatively be formed using conventional multilayer barrier films, which are processed as described herein. Barrier films including at least one layer of urethane material are advantageously processed as described herein to form balloon articles from half-sections that are produced by vacuum forming, e.g., vacuum thermoforming, and then bonded at their outer periphery to form a balloon article without openings in the weld line or any other location on the dome of the respective half-sections in the finished article. Conventional multilayer barrier films of such type may be manufactured either by co-extrusion of sealing layer(s) with outer layer(s), with or without adhesive, or by preformed film of outer layers adhesive laminated to preformed film of sealing layers. For example, co-extruded films of 3-4 layers can be utilized. Referring now to the drawings, FIG. 1 is a perspective view of an extruded laminate film 10 according to one embodiment of the invention. The extruded laminate film 10 includes outer film layers 14 and 16 of thermoplastic material, which have been extrusion laminated to a sealing layer film 12. The outer film layers 14 and 16 of thermoplastic material may comprise a polyurethane elastomer film, or other thermoplastic elastomer film, or any other thermoplastic material film that is gas-pervious in character and by itself has inadequate gas barrier character for the desired end use. The sealing layer, on which the thermoplastic material layers are extrusion laminated, provides a gas barrier film imparting the requisite gas-impervious character to the overall laminate for the intended use application. While the laminate of FIG. 1 is shown as comprising three layers, i.e., the outer layers of gas-pervious film material and the central layer of sealing film material, it will be recognized that the invention is not limited to such three-layer film constructs, but may comprise two layers, or alternatively more than three layers of material, including at least one outer layer of gas-pervious film and a sealing film layer imparting gas barrier character to the multilayer laminate. In multiple layer laminated films having three or more layers, the additional layers may be formed of any suitable material, to achieve any additional required mechanical or chemical resistance properties, and such additional layers may be extrusion laminated over the sealing film layer and/or outer layer(s), during the fabrication of the laminate. In a specific embodiment, a three-layer film of the type shown in FIG. 1 includes outer layers 14 and 16 of polyurethane elastomer, having a thickness of about 2 mils (0.0508 mm), and a sealing layer 12 of polyvinylidene chloride film having a thickness of about 1.35 mil (0.0343 mm). FIG. 2 is a front elevation view of a gastric occlusive device, according to one embodiment of the invention. The gastric occlusion device 20 includes a balloon 18 formed from half-sections 22 and 24, which are joined to one another at edge seam 26 to form an enclosed interior volume 28 of the balloon. The seam 26 may be formed by any suitable type of bonding technique. A preferred bonding technique is radio frequency welding, as discussed hereinafter. The two pieces of the balloon (half-sections 22 and 24) are preferably bonded circumferentially to one another to form a 360° seal having a seam devoid of any neck or opening therein. The balloon is shown in its inflated form, in which the interior volume 28 contains a head piece 30 bonded to an inside surface of the upper balloon half-section 22. Joined to the head piece 30 is a gas pill 32 holding an effervescent material. The head piece and laminated film are joined to one another by any suitable bonding means and/or method, and their junction suitably includes a self-healing seal valve through which water or moisture or other aqueous medium may be introduced to contact the effervescent material in the gas pill 32, e.g., from an associated catheter or liquid feed tube (not shown in FIG. 2). The effervescent material in the gas pill 30 can be of any suitable type that in contact with water, moisture, or physiological media reacts to liberate carbon dioxide or other inflating gas for the balloon, so that the balloon is transformed from an initial collapsed (deflated) state to the inflated state illustratively shown in FIG. 2. By way of example, the effervescent material can be a mixture of aspirin, sodium bicarbonate and citric acid, or other suitable material generating CO2 in the presence of water, moisture or physiological media. The balloon may also include a degradable seal if desired, which can be successively deteriorated by a physiological environment in which the balloon is deployed, so that the balloon deflates after a predetermined period of time, and can be more easily be removed, e.g., mechanically or physiologically, from the corporeal locus of deployment. For example, a degradable seal may be formed of an ethelene vinyl acetate (EVA)/hydroxycellulose blended material that is progressively degradable to create an opening in the balloon after a prolonged period of exposure to a physiological environment, at a thickness permitting the balloon to remain in an inflated state for a period of time sufficient for the desired treatment to be effected. Upon deterioration of the seal, an opening is produced in the balloon that permits the inflation gas to egress, and the deflated balloon may then be readily removed from the corporeal locus in which treatment is being carried out. FIG. 3 is a front elevation cross-sectional view of a vacuum forming assembly 50 for forming a balloon article of the type shown in FIG. 2. The assembly 50 includes a thermoforming die 52. The die has a block-like body 52 with a generally hemispherical cavity 54 therein, whose surface 60 communicates through gas withdrawal passages therein with the gas extraction plenum 56. The gas extraction plenum 56 communicates in turn with discharge passage 58. The discharge passage 58 can be coupled with a suitable vacuum source (not shown in FIG. 3), such as a vacuum pump, for extraction of gas from the thermoforming cavity when overlaid by the extrusion laminate film 62. Under the negative pressure imposed by the vacuum source, the central portion of the multilayer film 62 is drawn into the die cavity as shown, against the die cavity surface 60, and the evacuated gas is discharged from the die via the discharge passage 58 in the direction indicated by arrow A. The extruded laminate film 62 in such processing is at sufficient temperature for vacuum thermoforming, i.e., a temperature above the softening temperature of the thermoplastic polymeric material. Such temperature preferably is above the Vicat softening temperature of the thermoplastic polymeric laminate material, but below the deformation temperature of such laminate material. The Vicat softening temperature of polyurethane elastomers, for example, is usually from about 60° to about 150° C., depending on the nature of the specific polymer involved. The Vicat softening temperature is readily determinable within the skill of the art without undue experimentation, for any of various other suitable thermoplastic polymeric materials that may be employed in the extruded laminate. By applying negative pressure to the mold cavity so that the heated and softened thermoplastic polymeric laminate film is induced to conform to the shape of the mold cavity, the laminate is vacuum-molded to the required generally hemispherical shape. In lieu of the female mold structure shown in FIG. 3, a male mold may alternatively be employed to form the respective half-sections of the ballon article. The first and second half-sections of the balloon can be formed simultaneously, or they may be formed sequentially. The same sheet or web stock of extruded laminate material may be employed for such purpose, or different sheets of thermoplastic polymeric laminates may be employed, as illustrated. After thermo-vacuum molding two half-sections of the balloon by the arrangement shown in FIG. 3, the half-sections can be superimposed and bonded together at their margins (edges) by any of various suitable bonding methods, as for example the radio frequency welding method that is illustrated schematically in FIG. 4. FIG. 4 shows a base mold 80 having the superimposed multilayer laminate films 62 and 64 arranged in the cavity 82 so that the generally hemispherical half-sections of such films are in register with one another, with the head piece 30 and gas pill 32 assembly therebetween. The radio frequency welding die 70 is shown disposed above the base mold 80 and in position for downward translation in the direction indicated by arrows M, to weld films 62 and 64 to one another at the circumferentially extending weld region 66 by contact of the circumferentially extending welding ring 72 with the superposed film layers. Subsequent to such welding, the welded films may be removed from the cavity 82, and the welded sphere can be trimmed adjacent the outer periphery of the weld region 66, to yield the balloon article. Although radio frequency welding is a preferred technique for bonding of the respective half-sections of the balloon to one another, any of various other suitable bonding techniques may be employed in the broad practice of the present invention, as for example, adhesive bonding, electromagnetic bonding, hot plate welding, impulse heat induction bonding, insert bonding, spin welding, thermostacking, ultrasonic sealing or vibration welding, or various combinations of two or more of the foregoing techniques. In a preferred aspect, the two half-sections of the balloon are bonded together by radio-frequency welding as described in U.S. Pat. No. 5,833,915 for “Method of Welding Polyurethane Thin Film,” issued Nov. 10, 1998 to the present inventor. The disclosure of such patent hereby is incorporated herein by reference in its entirety, for all purposes. As discussed, the gas pill 32 containing the effervescent material can be secured to an interior surface of the balloon. Alternatively, the gas pill can simply be positioned in an unsecured state in the interior volume of the balloon. This is acceptable, provided that the gas pill is accessible to water, moisture or other medium serving to effect reaction of the effervescent material to produce carbon dioxide or other gas for inflation of the balloon in vivo. As a still further alternative, the balloon article may be fabricated with a gas supply tube, or otherwise be constructed so that the balloon is able to be inflated at the locus of use, if required to be delivered to such locus in an uninflated state. The balloon article may additionally be fabricated or adapted so that it is readily removable from the body of the patient, e.g., by means of a hook, loop, vacuum suction head or other engagement structure associated with a catheter, guide wire, or other extraction device. The extraction device in a specific embodiment may be provided with means for puncturing the inflated balloon in vivo to facilitate its removal from the body of a patient. It will therefore be seen that medical balloon articles are readily fabricated from multilayer laminates in accordance with the present invention, and are suitable for carrying out a wide variety of therapeutic interventions. It will be appreciated that the laminate film of the balloon may be utilized as a drug delivery device, with the film being coated on its outside surface with a therapeutic agent, e.g., an anti-viral agent, an anti-inflamatory agent, a time-release analgesic formulation, a clotting factor, etc. The balloon can also in another embodiment be utilized as a gas-retentive enclosure, e.g., as a coolant reservoir in which the gas retained in the interior volume of the balloon is water vapor, or other coolant medium. Thus, while the invention has been variously described hereinabove with reference to specific aspects, features and embodiments, it will be recognized that the invention is not thus limited, but rather extends to and encompasses other variations, modifications and alternative embodiments, such as will suggest themselves to those of ordinary skill in the art based on the disclosure herein. Accordingly, the invention is intended to be broadly construed and interpreted, as encompassing all such variations, modifications and alternative embodiments, within the spirit and scope of the claims hereinafter set forth. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention relates to an extrusion laminate film, and to products formed therefrom having a gas barrier character. In a specific embodiment, the invention relates to a gastric occlusive device fabricated using such film. 2. Description of the Related Art In the field of polymeric film technology, involving polymeric sheet stock or web-form material, typically having a thickness of less than about 25 mils, there is a need for gas-barrier films. Such gas barrier films may be employed for containment of a specific gas when used to form gas receptacles, or as a packaging, cushioning or preservative structure (e.g., when fabricated to contain gas species such as oxygen, nitrogen, argon, helium, carbon dioxide, water vapor, etc). Still other applications relate to the prevention or reduction of gas passage through the film, such as in instances in which any significant penetration of gas through the film may adversely impact an article, structure, material or region that is isolated from an adverse gas environment by the gas barrier film. In the aforementioned applications, the film material may be susceptible to forces and consequent stresses that cause failure of the film, e.g., by cracking, tearing, splitting, stress-softening, embrittlement or other material failure mechanisms. Specific applications of such gas barrier films may include the requirement of biocompatibility, in which the gas barrier film is required to function in or in connection with a physiological environment, whereby the film may be subjected to exposure to biological fluids, variations of temperature, pressure and pH, etc. There is presently a compelling need in the art for readily manufacturable, soft and supple yet durable and reliable gas barrier films for manufacture of medical devices as well as a wide variety of other product articles. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention relates to a gas barrier film, as well as to articles and devices incorporating such gas barrier film. In one aspect, the invention relates to a multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymeric material alone lacks such gas barrier character. In such multilayer film, the thermoplastic polymer film is appropriately selected for the specific barrier service to be accommodated by the multilayer film. In a preferred embodiment, wherein the multilayer film is employed as a structural component of a medical device, the thermoplastic polymer film is selected to exhibit biocompatibility, softness to the touch and good weldability (for film welding by welding techniques such as RF impulse welding, hot bar adhesive welding, ultrasonic welding, etc.). In another aspect, the invention relates to a gas-retentive enclosure comprising a multilayer film, wherein the multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character In another aspect, the invention relates to a gastric occlusive device, comprising: a balloon formed of a multilayer film comprising: a layer of sealing film, having main top and bottom surfaces; a layer of thermoplastic polymer film, on at least one of the main top and bottom surfaces of the layer of sealing film; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymeric material alone lacks such gas barrier character; and an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. A still further aspect of the invention relates to a method of therapeutic intervention for treatment of a patient in need of such treatment, such method comprising: introducing to a physiological locus of a patient in need of such therapeutic intervention a balloon formed of a multilayer film, wherein the multilayer film comprises: a layer of sealing film, having main top and bottom surfaces; and a layer of thermoplastic polymer film, laminated to the layer of sealing film, on at least one of the main top and bottom surfaces; wherein the sealing film has a composition and thickness imparting gas barrier character to the multilayer film and wherein the layer(s) of thermoplastic polymer film alone lacks such gas barrier character; with an effervescent material contained in said balloon, and arranged for contact with introduced liquid reactive with the effervescent material to liberate gas for inflation of the balloon. As used herein, the term “film” means a material in a sheet or web form, having a thickness of 50 mils (1.270 mm) or less. As used herein, the term “extrusion laminated” in reference to a film of thermoplastic material means that such film of thermoplastic material is deposited as an extruded melt film on (one or both sides of) the sealing layer film, so that the respective thermoplastic material and sealing layer films are consolidated with one another under elevated temperature conditions. The laminate preferably is formed under process conditions producing substantially uniform thickness of the multilayer film, with a thickness variation across the laminated film desirably being less than 20% and more preferably being less than 15% of the total thickness of the laminate. Other aspects, features and embodiments will be more fully apparent from the ensuing disclosure and appended claims. | 20040401 | 20110208 | 20051006 | 96643.0 | 3 | TRAN, THAO T | EXTRUSION LAMINATE POLYMERIC FILM ARTICLE AND GASTRIC OCCLUSIVE DEVICE COMPRISING SAME | SMALL | 0 | ACCEPTED | 2,004 |
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10,815,443 | ACCEPTED | System and method for IP handoff | A seamless vertical handoff method allows the network applications and connections on a mobile node to continue without disruption as it moves within a wireless overlay network that comprises multiple possibly overlapping layers of wireless networks (e.g., a WLAN and a WWAN) with different underlying technologies, providing mobile roaming capabilities. The method comprises a WLAN access point signal strength monitor for determining when to switch between WLAN and WWAN, and a network connection migration scheme that can move an active network connection from a wireless link of one technology to another wireless link of a different technology in a way that is transparent to the user, the remote end of the network connection, and the operator of the WWAN carrier. | 1. A vertical handoff system comprising: a first foreign agent providing connectivity to a network, the first foreign agent broadcasting a wireless local area network signal; a second foreign agent providing connectivity to the network via a wireless wide area network signal; a mobile node comprising executable code for performing a vertical handoff between the first foreign agent and the second foreign agent; and a home agent routing information to the mobile node through one of the first foreign agent and the second foreign agent according to an established connection of the mobile node. 2. The vertical handoff system of claim 1, wherein the mobile node further comprises a signal strength monitor. 3. The vertical handoff system of claim 1, wherein the mobile node comprises a buffer for caching information received through the first foreign agent prior to establishing a connection with the second foreign agent. 4. The vertical handoff system of claim 1, wherein the second foreign agent comprises a buffer for caching information to be transmitted to the mobile node. 5. The vertical handoff system of claim 1, wherein the home agent comprises a router for routing information transmitted from the mobile node. 6. The vertical handoff system of claim 1, wherein the executable code for performing the vertical handoff comprises: a link status monitor for monitoring a signal strength of the wireless local area network signal; and a communication daemon for initiating the vertical handoff upon determining the signal strength to be undesirable and for establishing connectivity between a mobile internet protocol module of the mobile node and the second foreign agent. 7. The vertical handoff system of claim 1, wherein the wireless local area network connects wirelessly to the mobile node via radio frequency electromagnetic airwaves. 8. The vertical handoff system of claim 1, wherein the wireless wide area network connects wirelessly to the mobile node via one of Code Division Multiple Access, Global System for Mobile Communications, General Packet Radio Service, Enhanced Data rate for Global Evolution or Wideband Code Division Multiple Access. 9. A vertical handoff method comprising: establishing a network connection to a network host via a wireless local area network; determining a strength of the wireless local area network connection to be at or below a threshold strength; and moving, seamlessly, the network connection to a wireless wide area network. 10. The method of claim 9, wherein the transition is transparent to a user and a remote end of the network connection. 11. The method of claim 9, wherein moving comprises buffering packets at a home agent and pacing packets sent to a mobile node, wherein the network connection exists between the home agent and the mobile node. 12. A method for vertical handoff in a wireless network vertical comprising: monitoring a wireless local area network signal carrying an active network connection; initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable; tunneling the active network connection over the wireless wide area network signal; and caching and replaying information over the wireless wide area network signal. 13. The method of claim 12, wherein initiating the vertical handoff comprises establishing a wireless wide area network connection to a mobile node. 14. The method of claim 12, wherein initiating the vertical handoff comprises caching information received by a mobile node over the wireless local area network signal. 15. The method of claim 14, wherein the caching of information received over the wireless local area network is performed before a wireless wide area network connection is established. 16. The method of claim 13, further comprising determining whether a second wireless local area network signal is desirable prior to initiating the vertical handoff. 17. The method of claim 16, further comprising initiating a horizontal handoff upon determining that the second wireless local area network signal is desirable. 18. The method of claim 13, further comprising initiating vertical handoff from the wireless wide area network signal to the wireless local area network signal upon determining that the wireless local area network signal is desirable. 19. The method of claim 13, wherein desirability corresponds to a threshold for measuring strength of a wireless signal. 20. The method of claim 13, wherein tunneling comprises redirecting a signal of a client side mobile internet protocol implementation from the wireless local area network signal to the wireless wide area network signal. 21. The method of claim 13, wherein tunneling comprises providing a communication agent using a protocol to talk to home agent and mobile node. 22. The method of claim 13, wherein tunneling comprises: providing a foreign agent for communicating with a mobile node and a home agent; establishing a forwarding tunnel between the home agent and the mobile node; authenticating the mobile node; and updating a routing table of the foreign agent to route packets. 23. The method of claim 13, wherein tunneling comprises tunneling packets from a home agent directly to a mobile node. 24. The method of claim 13, wherein tunneling comprises: intercepting traffic going to a mobile node belonging to an enterprise; and establishing a tunnel between the mobile node and a network address translation gateway, wherein communications between a mobile node and a communicating party is via the network address translation gateway. 25. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for vertical handoff in a wireless network, the method steps comprising: monitoring a wireless local area network signal carrying an active network connection; initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable; tunneling the active network connection over the wireless wide area network signal; and caching and replaying information over the wireless wide area network signal. | This application claims the benefit of U.S. Provisional Application No. 60/501,114, filed Sep. 8, 2003. BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to wireless roaming, and more particularly to a system and method for vertical handoff in a wireless network. 2. Discussion of Related Art Wireless connectivity is a burgeoning market in which consumers are coming to expect network access in a variety of venues, such as malls, hotels, public spaces, etc. Wireless Local Area Networks (WLAN) are providing the connectivity. Within these venues dead zones are a problem. Dead zones are pockets within a WLAN having reduced or no wireless signal for connecting to the network. As a mobile node moves into a dead zone, any connection to the network will be substantially degraded or dropped. The dead zones detract from the users experience of wireless connectivity. One method of limiting dead zones is to implement a network comprising different wireless technologies having different capabilities in a given geographic area. For a wireless device to move within such a network, a handoff is needed between wireless network cells to provide continuous connections to the network. Handoffs in wireless mobile networks can be characterized into two categories, horizontal handoff and vertical handoff. Horizontal handoff allows mobile nodes to move among wireless network cells that support the same wireless link technology. Vertical handoff allows device movement within a network environment that comprises heterogeneous wireless links. Because vertical handoff involves different types of connections, e.g., 802.11 and General Packet Radio Service (GPRS), handing a connection from one cell to another is slow as compared to horizontal handoff, and detracts from a user's wireless experience. For example, until the new connection is established, the mobile node is cut off from the network. Further, packet loss or delay during a handoff interval can incorrectly trigger a congestion control mechanism at the sender side of any Transmission Control Protocol (TCP) connections in which the mobile node is involved, thus greatly slowing down the throughput. No known system or method exists for seamless vertical handoff between different wireless technologies. Therefore, a need exists for a system and method for performing a seamless vertical handoff. SUMMARY OF THE INVENTION According to an embodiment of the present disclosure, a vertical handoff system comprises a first foreign agent providing connectivity to a network, the first foreign agent broadcasting a wireless local area network signal, and a second foreign agent providing connectivity to the network via a wireless wide area network signal. The system further comprises a mobile node comprising executable code for seamlessly performing a vertical handoff between the first foreign agent and the second foreign agent, and a home agent routing information to the mobile node through one of the first foreign agent and the second foreign agent according to an established connection of the mobile node. The mobile node further comprises a signal strength monitor. The mobile node comprises a buffer for caching information received through the first foreign agent prior to establishing a connection with the second foreign agent. The second foreign agent comprises a buffer for caching information to be transmitted to the mobile node. The home agent comprises a router for routing information transmitted from the mobile node. The executable code for performing the vertical handoff includes a link status monitor for monitoring a signal strength of the wireless local area network signal. The link status monitor further includes a communication daemon for initiating the vertical handoff upon determining the signal strength to be undesirable and for establishing connectivity between a mobile internet protocol module of the mobile node and the second foreign agent. The wireless local area network connects wirelessly to the mobile node via radio frequency electromagnetic airwaves. The wireless wide area network connects wirelessly to the mobile node via one of Code Division Multiple Access, Global System for Mobile Communications, General Packet Radio Service, Enhanced Data rate for Global Evolution, or Wideband Code Division Multiple Access. According to an embodiment of the present disclosure, a seamless vertical handoff method comprises establishing a network connection to a network host via a wireless local area network, determining a strength of the wireless local area network connection to be at or below a threshold strength, and moving, seamlessly, the network connection to a wireless wide area network. The transition is transparent to a user and a remote end of the network connection. The moving comprises buffering packets at a home agent and pacing packets sent to a mobile node, wherein the network connection exists between the home agent and the mobile node. According to an embodiment of the present disclosure, a method for vertical handoff in a wireless network vertical comprises monitoring a wireless local area network signal carrying an active network connection, initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable, tunneling the active network connection over the wireless wide area network signal, and caching and replaying information over the wireless wide area network signal. Initiating the vertical handoff comprises establishing a wireless wide area network connection to a mobile node. Initiating the vertical handoff comprises caching information received by a mobile node over the wireless local area network signal. The caching of information received over the wireless local area network is performed before a wireless wide area network connection is established. The method further comprises determining whether a second wireless local area network signal is desirable prior to initiating the vertical handoff. The method comprises initiating a horizontal handoff upon determining that the second wireless local area network signal is desirable. The method comprises initiating vertical handoff from the wireless wide area network signal to the wireless local area network signal upon determining that the wireless local area network signal is desirable. Desirability corresponds to a threshold for measuring strength of a wireless signal. Tunneling includes redirecting a signal of a client side mobile internet protocol implementation from the wireless local area network signal to the wireless wide area network signal. Tunneling includes providing a communication agent using a protocol to talk to home agent and mobile node. Tunneling includes providing a mobile internet protocol foreign agent for communicating with a mobile node and a home agent, establishing a forwarding tunnel between the home agent and the mobile node, authenticating the mobile node, and updating a routing table to route packets. Tunneling includes tunneling packets from a home agent directly to a mobile node. Tunneling includes intercepting traffic going to a mobile node belonging to an enterprise, and establishing a tunnel between the mobile node and a network address translation gateway, wherein communications between a mobile node and a communicating party is via the network address translation gateway. According to an embodiment of the present disclosure, a program storage device is provided, readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for vertical handoff in a wireless network. The method steps comprising monitoring a wireless local area network signal carrying an active network connection, initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable, tunneling the active network connection over the wireless wide area network signal, and caching and replaying information over the wireless wide area network signal. BRIEF DESCRIPTION OF THE FIGURES Preferred embodiments of the present invention will be described below in more detail, with reference to the accompanying drawings: FIG. 1 is a diagram of a system according to an embodiment of the present disclosure; FIG. 2 is a diagram of an OSI stack; FIG. 3A is a diagram of a network according to an embodiment of the present disclosure; FIG. 3B is a diagram of a network according to an embodiment of the present disclosure; FIG. 4A is a flow chart of a method according to an embodiment of the present disclosure; FIG. 4B is a flow chart of a method according to an embodiment of the present disclosure; FIG. 5 is a flow chart of a method according to an embodiment of the present disclosure; FIG. 6 is an illustration of a system architecture according to an embodiment of the present disclosure; and FIG. 7 is a Gant chart according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS To support seamless vertical handoff between a wireless wide area network (WWAN), such as GPRS, and a wireless local area network (WLAN), a WLAN link status is monitored to determine whether to use WLAN technology or a WWAN link. A Mobile IP (internet protocol) implementation is provided for establishing connectivity to the WLAN link, and packet scheduling and buffering mechanisms are supported to accommodate transmission characteristics of the WWAN link. Link monitoring may be carried out by an external software module, which in turn triggers network-layer handoff supported by Mobile IP when a vertical handoff is needed. The Mobile IP implementation may be used whether or not a foreign agent for WWAN link and a mobile node are on the same subnet. According to an embodiment of the present disclosure a heterogeneous wireless network comprises two foreign agents using different, possibly overlapping, wireless transmission technologies. A first foreign agent is based on a WLAN. In a WLAN there are no physical connection wires needed between the mode node and the infrastructure. The signals are sent using radio frequency electromagnetic airwaves. The Institute of Electrical and Electronics Engineers (IEEE) 802.11a, b, and g are WLAN standards and may be referred to as Wi-Fi. A second foreign agent provides connectivity via a WWAN, for example, Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), GPRS, Enhanced Data rate for Global (or GSM) Evolution (EDGE) and Wideband-CDMA. An example of a heterogeneous wireless network is a wireless overlay network, in which different wireless technologies co-exist in the same geographical area, for example, infrared/Bluetooth for personal area networking, 802.11 based WLAN for local area networking, and cellular communication networks for wide area networking. A wireless overlay network permits a user to choose to use the most appropriate wireless link technology to satisfy a need. Throughout the disclosure the term connection includes wired and/or wireless communications links unless otherwise specified. Each foreign agent is connected to a home agent across an IP network, such as the Internet. A mobile node, such as a laptop computer, is capable of connecting to the first foreign agent and/or the second foreign agent. Further, the mobile node comprises functionality for monitoring the signal strength of packets from the foreign agent on the WLAN, and upon determining a weakening signal, seamlessly moving the user's on-going network connections to another foreign agent that has a more desirable signal, without disrupting the continuity of these connections. Signal strength can be measured in decibels compared to one milliwatt (or dBm). Various known techniques exist for measuring signal strength, and typically client software for operating a wireless network interface comprises a signal strength monitor. The desirability of the signal is related to signal strength. The mobile node determines signal strength for one or more available signals provided by respective foreign agents, and selects a signal among the one or more signals according to strength. Other criteria for selecting a signal can include, for example, signal strength over time, e.g., whether the signal is becoming stronger or weaker over time, and user preferences for particular foreign agents. According to an embodiment of the present disclosure, the seamless vertical handoff occurs without user input. The user does not need to be aware that a handoff has happened. Further, upon detecting that the signal of the first foreign agent, or any other WLAN foreign agent, has reached a desirable strength, the mobile node can perform a handoff back to the WLAN signal. Further, connectivity providers, e.g., WWAN service providers operating WWAN foreign agents, may not need to implement changes to accommodate the mobile node. The system and/or method of the mobile node may be independent of the WWAN service provider. The ability to automatically and seamlessly switch between different foreign agents, regardless of their underlying connectivity technology and their operators, enables a mobile node to maintain connectivity at all times and at a lower cost. That is, cellular network usage is typically more expensive than that of WLAN connectivity. Seamless handoff makes it possible for users to use WLAN connectivity when it is determined to be desirable while enjoying continuous connectivity. It is to be understood that the present invention may be implemented in various forms of hardware, software, firmware, special purpose processors, or a combination thereof. In one embodiment, the present invention may be implemented in software as an application program tangibly embodied on a program storage device. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Referring to FIG. 1, a mobile node 101, such as a laptop computer or handheld device, for implementing the present invention can comprise, inter alia, a central processing unit (CPU) 102, a memory 103 and an input/output (I/O) interface 104. The computer system 101 is generally coupled through the I/O interface 104 to a display 105 and various input devices 106 such as a mouse and keyboard. The support circuits can include circuits such as cache, power supplies, clock circuits, and a communications bus. The memory 103 can include random access memory (RAM), read only memory (ROM), disk drive, tape drive, etc., or a combination thereof. The present invention can be implemented as a routine 107 that is stored in memory 103 and executed by the CPU 102 to process the signal from the signal source 108. As such, the mobile node 101 is a general-purpose computer system that becomes a specific purpose computer system when executing the routine 107 of the present invention. The mobile node 101 also includes an operating system and micro instruction code. The various processes and functions described herein may either be part of the micro instruction code or part of the application program (or a combination thereof), which is executed via the operating system. In addition, various other peripheral devices may be connected to the computer platform such as an additional data storage device and a printing device. It is to be further understood that, because some of the constituent system components and method steps depicted in the accompanying figures may be implemented in software, the actual connections between the system components (or the process steps) may differ depending upon the manner in which the present invention is programmed. Given the teachings of the present invention provided herein, one of ordinary skill in the related art will be able to contemplate these and similar implementations or configurations of the present invention. According to an embodiment of the present disclosure, handoff can take place at different layers of the Open Standards Interconnect (OSI) protocol stack. An example of the OSI protocol stack is shown in FIG. 2. The functions of each layer of the OSI are well known in the art. When a mobile node switches from one WLAN cell to another WLAN cell, the network interface hardware performs the link-layer handoff, which changes the association of the mobile node from one access point to another. To maintain un-disrupted network service, the mobile node performs a network-layer handoff, which ensures that the device can continue to communicate with other Internet hosts even when the mobile node moves into a different subnet. According to an embodiment of the present disclosure, and referring to FIG. 3A, a home agent 301 and foreign agents 302-303 are connected on a wired network. The WLAN foreign agent 302 periodically broadcasts Mobile IP advertisements on the WLAN to which a mobile node 101 is attached. For horizontal handoff in the network, whenever a mobile node migrates from a first subnet to a second subnet, it starts receiving the Mobile IP advertisements from the second subnet's corresponding WLAN foreign agent. The Mobile IP software running on the mobile node intercepts these advertisements and sends a registration request to a newly discovered WLAN foreign agent of the second subnet. After authentication and consultation with the home agent, an IP-over-IP tunnel is established between the home agent and the new WLAN foreign agent. Tunneling includes, for example, encapsulating one packet within another packet. Various methods for tunneling exist, including, for example, the Layer 2 Tunneling Protocol and the Point-to-Point Tunneling Protocol. More generally, tunneling is described in RFC 1853, wherein an outer IP header is added before the original IP header. Between the outer IP header and the original IP header any other headers for the path, such as security headers specific to the tunnel configuration may be added. The outer IP header includes source and destination information identifying the endpoints of the tunnel. The inner IP header includes source and destination information identifying the original sender and recipient of the datagram. For a mobile node to move across IP subnets and maintain all the active network connections, an indirection mechanism is needed to channel packets between the mobile node and the parties it is communicating with. The packet indirection mechanism enables a mobile node to keep its IP address unchanged regardless of its geographic location. The packet indirection mechanism is notified whenever the mobile node moves into a different subnet, wherein it can adjust the redirection parameter accordingly. Mobile IP is an example of a packet indirection mechanism. Mobile IP has been extended to implement vertical handoff. The extension includes a WLAN link status-monitoring module to the mobile node. In the Mobile IP framework, a foreign agent channels packets between a mobile node and its home agent, and a mobile node and its foreign agent typically reside on the same subnet. Unlike WLAN, it is unlikely that the GPRS link's foreign agent can reside on the same site as mobile node, because the GPRS service provider does not necessarily support Mobile IP. A tunnel may be established between a mobile node and its GPRS link's foreign agent to channel traffic between a mobile node and its communicating parties. Note that this is in addition to the IP-IP channel between a foreign agent and home agent in Mobile IP. While one end of this tunnel always resides in the mobile node, there are at least three possible ways to implement the other end of the tunnel. First, it could be a special communication agent, which uses a proprietary protocol to talk to home agent and mobile node. Second, it could be a generic Mobile IP foreign agent that communicates with mobile node and home agent in a standard way, and sets up a forwarding tunnel between home agent and mobile node, authenticates the mobile node, and updates its own routing table to route packets appropriately. Support is added for tunneling with mobile node to the existing foreign agent implementation. Third, the home agent can directly tunnel packets to a mobile node without the help of any intermediate agent. It is also possible to implement vertical handoff in a way that is independent of Mobile IP. For example, within network address translation (NAT) technology for packet interception and redirection an enterprise-wide NAT gateway may be used to intercept traffic going to mobile nodes belonging to the enterprise. A tunnel is set up between each mobile node and the NAT gateway so that the communications between a mobile node and its communicating parties always go through the NAT gateway. Whenever a mobile node changes its IP address, it informs the NAT gateway so that the old tunnel can be torn down and a new tunnel can be established. Since this tunnel can run over a WLAN, as well as a GPRS link, this architecture provides a unified framework for both vertical and horizontal handoff. A new IP address may be acquired through DHCP for example. Further, an authentication protocol is issued between mobile node and NAT gateway. For a Mobile IP implementation for vertical handoff the access point of a WWAN link is typically a layer-3 dial-up server, rather than a layer-2 bridge, as in the case of a WLAN access point. As shown in FIG. 3B, as the mobile node 101 exits the service area 306 of the WLAN foreign agent, it detects that the signal strength of the WLAN is decreasing. Upon determining that the signal strength is equal to or less than a first threshold strength, the mobile node initiates a handoff. If no WLAN foreign agents are present with a signal strength above a second threshold, e.g., a 10% above the first threshold, the mobile node initiates a vertical handoff. The mobile node 101 establishes a new connection with the WWAN foreign agent 303 (e.g., a GPRS foreign agent), and tunnels all its active network connections on this new connection while maintaining its IP address. Because the WWAN interface of the mobile node is typically behind a NAT gateway, the tunnel between the mobile node and the WWAN foreign agent is a TCP tunnel, rather than the IP-over-IP tunnel. The round-trip delay on a WWAN link, such as GPRS, may be long; the number of interaction messages between a mobile node and the WWAN foreign agent should be reduced to the minimum. WWAN foreign agent advertisements are cached and replayed to the mobile node so that interactions between the WWAN foreign agent and the mobile node conform to a Mobile IP specification. Thus, the vertical handoff latency is reduced to one round-trip delay on the WWAN link. To minimize packet loss during a vertical handoff interval, a mobile node may initiate a vertical handoff anticipatively so that it can buffer additional packets from the WLAN foreign agent while it switches to the WWAN foreign agent. In addition, the WWAN foreign agent also buffers packets from the home agent. The packets are paced at a controlled rate on the WWAN link so that packet drops are minimized. Through both buffering and traffic shaping, packet loss is reduced to substantially zero. When a mobile node uses a GPRS link, it needs to obtain an IP address for its GPRS device. Because of lack of public IP addresses, the GPRS service provider typically uses an NAT gateway to translate between public IP addresses and addresses assigned to mobile nodes' GPRS devices. Thus, a mobile node initiates all network connections it has with the outside world through GPRS. A mobile node decapsulation mode and co-located care of address mechanism are not used when there is no foreign agent in the infrastructure. In mobile node decapsulation mode, an IP-over-IP tunnel is established directly between a mobile node and the home agent without an intermediate foreign agent. One end point of the tunnel is bound to the IP address of a mobile node, which is typically obtained through a standard protocol such as DHCP or some other static address assignment mechanism. For inbound packets to reach a mobile node through an NAT gateway, they need to be part of a connection initiated by the mobile node. An IP-over-TCP tunneling mechanism may be used. The mobile node initiates the TCP tunnel so that the NAT gateway on the GPRS network can allow bidirectional traffic in this connection. Use of TCP for tunneling ensures that the tunneled data reaches the destination in a reliable manner. A virtual network device, tcptun, is used that is exposed to Mobile IP software. This virtual device implements the TCP tunneling mechanism over an already established TCP connection with the GPRS foreign agent. It also emulates the activities of a network interface for all inbound packets received over the TCP connection, thus enabling connectivity over a LAN with the GPRS foreign agent. When a vertical handoff between the WLAN interface and the GPRS interface is needed, a horizontal handoff is triggered between the WLAN interface and the virtual device for GPRS interface. The home agent 301 acts as a proxy for the mobile node 101, intercepting incoming packets intended for the mobile node 101 and transmitting the incoming packets to the WLAN foreign agent 302 over an IP-over-IP tunnel. The foreign agent decapsulates the packets coming from the tunnel and forwards the packets to the mobile node. Similarly, packets that a mobile node transmits are received by the WLAN foreign agent and are tunneled over to the home agent 301, which further routes them to the true destination on the Internet 305. The home agent 301 is a node in the home subnet that provides a fixed IP address abstraction for mobile nodes. Each foreign agent 302-303 is an indirection point for routing. The tunnel is between the home agent and a foreign agent. A WLAN foreign agent is associated with a wireless access network, and periodically broadcasts advertisements to announce its presence to mobile nodes. Accordingly, the mobile nodes are mobility aware of the WLAN environment. When a mobile node is in a foreign subnet, the mobile node communicates with Internet hosts through triangle routing. Triangle routing is a process of sending and receiving packets to the mobile node. Although a mobile node does not need to send packets via its home agent, tunneling out-going packets to the home agent is a preferred mode of routing because it avoids various issues such as ingress and egress filtering that the firewalls at the foreign and home sites perform. Whenever a mobile node migrates to a new foreign subnet, it binds with the foreign agent of the new foreign subnet, and tears down the association with the foreign agent in the old subnet. When a mobile node returns to its home subnet, standard routing is resumed. The process of switching from one foreign agent to another as a mobile node moves across adjacent wireless IP subnets is Mobile IP handoff. The mobile node preserves its own IP address while roaming between horizontal and vertical agent. No modification may be needed for non-mobile nodes, e.g., other devices connected to the network, to communicate with the mobile node. In Mobile IP, there could be multiple network interfaces in a mobile node, but only one of the active interfaces may be used for external communication. An interface is active if advertisements from some mobile agent are received on that interface. The mobile node assumes the task of triggering a Mobile IP handoff, where a mobile node switches from WLAN interface to the virtual interface or vice versa. To make effective use of WLAN bandwidth and GPRS link bandwidth, the mobile node makes the handoff decisions intelligently. For this purpose, the mobile node implements a decision module that monitors, for example, the WLAN signal strength, quality, and noise level. Whenever the communication over WLAN starts degrading and the signal strength falls below a certain threshold, the mobile node triggers a handoff from WLAN interface to the virtual interface. The handoff triggering is carried out by sending multiple foreign agent advertisements on behalf of the GPRS foreign agent, through the virtual interface, up to the TCP/IP stack of the mobile node. This enables Mobile IP to carry out a network-layer handoff and start using the virtual interface. Once the WLAN signal strength becomes available again, Mobile IP switches back to the WLAN interface by holding off the foreign agent advertisements on the GPRS link. It may so happen that the mobile device is in a region where the signal strength is close to the threshold value but fluctuates in a range. This would set off multiple handoffs back and forth. To address this issue, the decision module may use a two level thresholding scheme. Instead of choosing just one threshold, a high watermark threshold and a low watermark threshold may be selected. The decision module triggers a handoff from WLAN to GPRS if the signal falls below the low watermark threshold. A reverse handoff is triggered only when the signal value improves above the high watermark threshold. The distance between high and low watermarks should be more than an expected fluctuation range of radio signals. This ensures that a handoff from WLAN to GPRS is triggered only when the mobile node is moving away from the network, and similarly, the reverse handoff is triggered when the mobile node is moving towards the WLAN. Traffic monitoring, filtering, and shaping over the GPRS link may be used to maintain a desired level of quality of service. Since traffic is tunneled through the TCP connection between the mobile node and the GPRS foreign agent, the traffic prioritization may be carried out at connection end-points. A traffic shaping mechanism is implemented to improve the utilization of GPRS link and to provide quality of service guarantee to critical applications. According to an embodiment of the present disclosure, a low-latency network-layer vertical handoff leverages Mobile IP, WWAN dial-up server, and PAP (Password Authentication Protocol) stack. The system comprises a WLAN link status monitor on the mobile node that determines when to switch from WLAN to WWAN and when to switch from WWAN to WLAN to minimize WAN connectivity charges. The system comprises an in-kernel IP traffic redirection mechanism that moves traffic descending from the local TCP-IP stack onto a TCP tunnel over the WWAN link or to an WLAN interface, depending on which interface is active currently. Further, intelligent packet buffering at the mobile nodes reduces the performance impact of long vertical handoff latency. Referring to FIG. 4, a method for vertical handoff in a wireless network vertical comprises monitoring a WLAN signal 401. Upon determining that the WLAN signal has become degraded 402, as compared to a threshold, a horizontal handoff is initiated. Upon determining that no desirable horizontal connection is available, a vertical handoff is initiated 403. Active network connections are tunneled on the established connection while maintaining an IP address 404. Information to be sent over the WWAN connection is cached and replayed at a controlled rate 405. Referring to FIG. 4B, initiating the vertical handoff 403 comprises establishing a WWAN connection 406 and caching information received over the WLAN 407. The caching of information received over the WLAN is performed before the WLAN connection is torn down or dropped due to, for example, loss of signal strength. Referring to FIG. 5, the initiation of a handoff 403 comprises detecting that a WLAN signal currently being used has a strength lower than a desirable level, for example, as compared to a threshold level 501. Determining that switch connectivity to a WWAN foreign agent is needed 502. For example, the mobile node may determine that no other WLAN foreign agent is available for establishing a connection. The mobile node sends a packet to a WWAN foreign agent indicating that connectivity is needed 503. The packet sent to the WWAN foreign agent indicates an identification of the mobile node. The mobile node will continue to listen to the WLAN signal for any packets that have not yet arrived. The mobile node establishes a TCP connection to the WWAN foreign agent if packets are to be sent through the WWAN foreign agent 504. It should be noted that different schemes may be implemented by the WWAN service providers operating the WWAN foreign agents. For example, a WWAN service provider may charge for packet traffic only and not charge for establishing a connection. In this example, the mobile node may freely establish connections to reduce handoff latency, and consider only the volume of packets to be trafficked across the network. In another example, the WWAN service provider may charge for establishing a connection and connectivity time after establishing the connection. In this example, the mobile node may consider the latency of the handoff time as part of the initiation of WWAN connectivity as a tradeoff between WWAN service provider charges and handoff latency. Various models may be used for determining a desirable tradeoff. These models may be formulated according to a user preference for, for example, low latency or low cost of operation. A prototype has been implemented under the Linux operating system. Referring to FIG. 6, the mobile node 101 and GPRS foreign agent 303 include communication daemons 601 and 602, respectively. The communication daemons 601-602 establish a TCP connection with each other over a GPRS network. A virtual interface of the mobile node 605 and a virtual interface of the GPRS foreign agent 606 are exposed to the Mobile IP software 603 and 604, respectively. Packets transferred through the virtual interfaces are tunneled over the TCP connection. The communication daemon 601 on mobile node interacts with the decision module for triggering vertical handoff. The communication daemons 601 and 602 also implement the traffic monitoring and filtering logic for effectively using the GPRS link bandwidth. The Mobile IP software 603 of the mobile node 101 includes a link status monitor 607 for monitoring a signal strength of the wireless local area network signal, and a vertical handoff initiation module for initiation the vertical handoff upon determining the signal strength to be undesirable. The mobile node supports WLAN link availability monitoring, TCP tunneling, traffic shaping and multiple network devices, and foreign agent needs to be modified to support TCP tunneling and traffic shaping. Mobile IP software may be used to support an early-expiration policy for mobile agent advertisements to facilitate the handoff process. The primary entities responsible for communication between the mobile node and the GPRS foreign agent are the communication daemons (CommD) running on both nodes. The communication daemons on the mobile nodes act as clients to the communication daemon on the GPRS foreign agent. The communication daemons are responsible for establishing and maintaining the TCP tunnel between a mobile node and the GPRS foreign agent. The communication daemons are also responsible for providing network Quality of Service to different applications running on mobile nodes. The communication daemon on a mobile node is responsible for interacting with other local components like, the virtual device and the decision module. It is also responsible for triggering the Mobile IP handoff. To simulate vertical handoff with horizontal handoff, a virtual network device, called tcptun, may be implemented. This virtual device is exposed to the Mobile IP software and the communication daemon. The generic Virtual Network Device support in Linux kernel may be used to implement TCP tunneling. Similar support is also available in Windows operating system through the NDIS miniport abstraction. The tcptun device exposes an API to be used by the communication daemons to read and write network packets. The packets that are supposedly transmitted over tcptun are handed over to the communication daemon to be tunneled over the TCP connection. The packets received over the TCP tunnel are given to tcptun, which in turn, are given to the operating system TCP/IP stack in a decapsulated form. Thus, from TCP/IP stack point of view, the virtual device is just another network interface. During the system initialization, the tcptun device configuration, such as IP address, subnet mask, etc., is assigned the same value as that of the WLAN network interface card (NIC). From this point onwards, the Mobile IP software starts listening on this device for mobile agent advertisements. On reception of GPRS foreign agent advertisements on tcptun, Mobile IP software registers with the foreign agent using the same device. Once the registration is successful, the routing table entries are updated to set the tcptun device as the default interface for all outbound packets bearing the mobile node home IP address as the source address. These outbound packets are read by the communication daemon and are tunneled over the TCP connection to the GPRS foreign agent, which takes care of further routing. During the handoff between WLAN and GPRS, there is a possibility of packet loss because of unavailability of the wireless interface and the delay in registration. Packet loss for upstream traffic is reduced or eliminated by buffering the packets and retransmitting them after handoff completion. To buffer the packets that are transmitted using the WLAN NIC, a NetFilter mechanism is used, which is available in Linux kernel. Using NetFilters, packets that are going to be transmitted over the wireless NIC may be captured. These packets are buffered in tcptun internal buffers. After a handoff from WLAN to GPRS is complete, tcptun transparently hands over buffered packets to the communication daemon to tunnel to the GPRS foreign agent. When a handoff from GPRS to WLAN takes place, the tcptun device retransmits the buffered packets that were sent using the tunnel during the handoff. The retransmission is carried out over the wireless NIC. This approach completely eliminates the data loss of upstream traffic. The amount of buffering can be configured by the communication daemon. The TCP connection may be setup by the mobile node as only the hosts residing behind NAT can initiate outgoing connections and no incoming connections are allowed. The mobile node communication daemon is responsible for initiating the dial out procedure on GPRS links and establishing the TCP connection. During system initialization, the mobile node communication daemon initializes the tcptun virtual device and connects to the GPRS network using GPRS interface. It also updates the routing table entries to set the GPRS interface as the default device for communication with the GPRS foreign agent. Once the TCP connection with the GPRS foreign agent is established, it receives all packets that are broadcast by the GPRS foreign agent. These packets include the Mobile IP agent advertisements. The mobile node communication daemon caches these advertisements without forwarding them to the tcptun virtual device. It also interacts with the decision module regarding the signal strength and quality of WLAN link. Based on inputs from the decision module, it initiates a vertical handoff by triggering a horizontal handoff. The horizontal handoff is triggered by releasing the cached foreign agent advertisements to the tcptun virtual device. On reception of these advertisements, Mobile IP software immediately initiates a handoff. From this point onwards, the mobile node uses the tcptun virtual device for all its external communications. In effect, it uses the GPRS link through the foreign agent communication daemon. When WLAN link later becomes available again, the decision module informs the communication daemon of this change. This results in mobile node communication daemon filtering out the GPRS foreign agent advertisements, and eventually a handoff from GPRS to WLAN. Subsequently Mobile IP software uses the WLAN NIC again after due registration with the mobile agent on the WLAN. The mobile node communication daemon also implements a traffic prioritization mechanism to effectively use the upstream bandwidth of the GPRS link. The foreign agent communication daemon acts as a server for mobile node communication daemons running on mobile nodes. It acts as a router and a mobile IP foreign agent for all GPRS-capable mobile nodes in an enterprise. After startup, like mobile node communication daemon, it initializes the tcptun virtual device, and listens on a well-known port for incoming TCP connections from mobile node communication daemons. Once a TCP connection is established, the interaction with the virtual device is similar to that of mobile node communication daemon. The foreign agent communication daemons demultiplex packets that are transmitted using the tcptun virtual device over multiple TCP connections. For this purpose it maintains a mapping between the home address of the mobile node and the connections. Every outgoing packet is examined to determine the destination address, based on which, the appropriate TCP connection is used to tunnel the packet. All relevant broadcasts, such as, mobile agent advertisements are transmitted over all connections. Foreign agent communication daemon also implements a traffic prioritization mechanism to use the downstream bandwidth effectively. Since the GPRS foreign agent is expected to support multiple mobile nodes belonging to an enterprise, its scalability is an important design consideration. Assuming that the GPRS foreign agent is connected to the enterprise network, the downstream traffic to mobile nodes is received by the GPRS foreign agent from the enterprise network, typically home agent, and the upstream traffic from the mobile nodes is received from the WAN. The upstream traffic from each mobile node is of the order of around 10 Kbps. Compared with current wired network capacities, this is relatively modest. Thus, the network scalability of GPRS foreign agent is solely determined by the amount of downstream traffic it needs to service. The decision module on mobile node is responsible for triggering Mobile IP handoffs. The handoff decisions are based on the monitored signal strength, quality, and noise levels for the wireless network interface. The Wi-Fi network cards expose these values to the device driver. The signal quality for WLANs is determined by computing the difference between the background noise and the signal strength. The decision module periodically polls the device driver statistics to observe a change in these values. The decision module computes an average of these values using a fixed number of previous samples. The averaging scheme is used to eliminate the effects of sudden surges or drops in the observed signal strength values. When the observed average signal level falls below a predetermined low watermark threshold, the decision module notifies the mobile node communication daemon to initiate a vertical handoff. The mobile node communication daemon responds to this notification by sending multiple cached GPRS foreign agent advertisement over the tcptun virtual device. Mobile IP responds to these advertisements by sending registration requests to the GPRS foreign agent and upon success, starts using the virtual device. A reverse process is carried out when the signal strength improves beyond a predetermined high watermark threshold. The decision module employs this two-level thresholding scheme to avoid oscillating handoffs between WLAN and GPRS interfaces. Communication daemons implement a traffic prioritization mechanism loosely based on DiffServ expedited forwarding specifications. Because a mobile node can have multiple TCP/UDP connections going on simultaneously, this traffic prioritization mechanism is designed to regulate these TCP/UDP connections, which share the same TCP tunnel. There are multiple priority queues associated with each TCP tunnel. Each packet sent over a TCP tunnel is examined for its type. If a packet is Mobile IP control message, such as, registration, deregistration, advertisement, etc., the packet is placed in the highest priority queue. Next, the mobile users are allowed to configure the relative priorities among different classes of traffic depending on the quintuple specification as used in Wireless Rether protocol, e.g.,{SrcAddr, SrcPort, DestAddr, DestPort, Protocol}. For each packet, a lookup is performed in the specified user policies and an appropriate priority queue is selected. The packets are transmitted over the TCP connection in a paced manner to match the GPRS bandwidth. The packets from higher priority queue are dispatched before the packets from lower priority queues. When the packets arrive in a queue faster than the dispatching rate the packets are dropped in a tail drop fashion. This priority mechanism ensures that the meager GPRS bandwidth is efficiently used by applications that are of greater interest to the mobile node users. FIG. 7 shows a Gant chart for Mobile IP handoff for both WLAN to GPRS and GPRS to WLAN scenarios according to the prototype implementation. The starting point in the chart corresponds to the instance when the decision module notifies the communication daemon to trigger the handoff. In WLAN to GPRS handoff, the cached GPRS foreign agent (FA) advertisement is released by communication daemon. Mobile IP responds to this advertisement by invalidating the previous agent advertisement and sending a registration. The GPRS foreign agent responds with registration reply. The length of the duration corresponds to the large round trip times on GPRS link. It should be noted however, that the time periods shown in FIG. 7 may increase or decrease with changes in the underlying technology and are for example purposes only. Having described embodiments for a system and method for vertical handoff in a wireless network, it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments of the invention disclosed which are within the scope and spirit of the invention as defined by the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present disclosure relates to wireless roaming, and more particularly to a system and method for vertical handoff in a wireless network. 2. Discussion of Related Art Wireless connectivity is a burgeoning market in which consumers are coming to expect network access in a variety of venues, such as malls, hotels, public spaces, etc. Wireless Local Area Networks (WLAN) are providing the connectivity. Within these venues dead zones are a problem. Dead zones are pockets within a WLAN having reduced or no wireless signal for connecting to the network. As a mobile node moves into a dead zone, any connection to the network will be substantially degraded or dropped. The dead zones detract from the users experience of wireless connectivity. One method of limiting dead zones is to implement a network comprising different wireless technologies having different capabilities in a given geographic area. For a wireless device to move within such a network, a handoff is needed between wireless network cells to provide continuous connections to the network. Handoffs in wireless mobile networks can be characterized into two categories, horizontal handoff and vertical handoff. Horizontal handoff allows mobile nodes to move among wireless network cells that support the same wireless link technology. Vertical handoff allows device movement within a network environment that comprises heterogeneous wireless links. Because vertical handoff involves different types of connections, e.g., 802.11 and General Packet Radio Service (GPRS), handing a connection from one cell to another is slow as compared to horizontal handoff, and detracts from a user's wireless experience. For example, until the new connection is established, the mobile node is cut off from the network. Further, packet loss or delay during a handoff interval can incorrectly trigger a congestion control mechanism at the sender side of any Transmission Control Protocol (TCP) connections in which the mobile node is involved, thus greatly slowing down the throughput. No known system or method exists for seamless vertical handoff between different wireless technologies. Therefore, a need exists for a system and method for performing a seamless vertical handoff. | <SOH> SUMMARY OF THE INVENTION <EOH>According to an embodiment of the present disclosure, a vertical handoff system comprises a first foreign agent providing connectivity to a network, the first foreign agent broadcasting a wireless local area network signal, and a second foreign agent providing connectivity to the network via a wireless wide area network signal. The system further comprises a mobile node comprising executable code for seamlessly performing a vertical handoff between the first foreign agent and the second foreign agent, and a home agent routing information to the mobile node through one of the first foreign agent and the second foreign agent according to an established connection of the mobile node. The mobile node further comprises a signal strength monitor. The mobile node comprises a buffer for caching information received through the first foreign agent prior to establishing a connection with the second foreign agent. The second foreign agent comprises a buffer for caching information to be transmitted to the mobile node. The home agent comprises a router for routing information transmitted from the mobile node. The executable code for performing the vertical handoff includes a link status monitor for monitoring a signal strength of the wireless local area network signal. The link status monitor further includes a communication daemon for initiating the vertical handoff upon determining the signal strength to be undesirable and for establishing connectivity between a mobile internet protocol module of the mobile node and the second foreign agent. The wireless local area network connects wirelessly to the mobile node via radio frequency electromagnetic airwaves. The wireless wide area network connects wirelessly to the mobile node via one of Code Division Multiple Access, Global System for Mobile Communications, General Packet Radio Service, Enhanced Data rate for Global Evolution, or Wideband Code Division Multiple Access. According to an embodiment of the present disclosure, a seamless vertical handoff method comprises establishing a network connection to a network host via a wireless local area network, determining a strength of the wireless local area network connection to be at or below a threshold strength, and moving, seamlessly, the network connection to a wireless wide area network. The transition is transparent to a user and a remote end of the network connection. The moving comprises buffering packets at a home agent and pacing packets sent to a mobile node, wherein the network connection exists between the home agent and the mobile node. According to an embodiment of the present disclosure, a method for vertical handoff in a wireless network vertical comprises monitoring a wireless local area network signal carrying an active network connection, initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable, tunneling the active network connection over the wireless wide area network signal, and caching and replaying information over the wireless wide area network signal. Initiating the vertical handoff comprises establishing a wireless wide area network connection to a mobile node. Initiating the vertical handoff comprises caching information received by a mobile node over the wireless local area network signal. The caching of information received over the wireless local area network is performed before a wireless wide area network connection is established. The method further comprises determining whether a second wireless local area network signal is desirable prior to initiating the vertical handoff. The method comprises initiating a horizontal handoff upon determining that the second wireless local area network signal is desirable. The method comprises initiating vertical handoff from the wireless wide area network signal to the wireless local area network signal upon determining that the wireless local area network signal is desirable. Desirability corresponds to a threshold for measuring strength of a wireless signal. Tunneling includes redirecting a signal of a client side mobile internet protocol implementation from the wireless local area network signal to the wireless wide area network signal. Tunneling includes providing a communication agent using a protocol to talk to home agent and mobile node. Tunneling includes providing a mobile internet protocol foreign agent for communicating with a mobile node and a home agent, establishing a forwarding tunnel between the home agent and the mobile node, authenticating the mobile node, and updating a routing table to route packets. Tunneling includes tunneling packets from a home agent directly to a mobile node. Tunneling includes intercepting traffic going to a mobile node belonging to an enterprise, and establishing a tunnel between the mobile node and a network address translation gateway, wherein communications between a mobile node and a communicating party is via the network address translation gateway. According to an embodiment of the present disclosure, a program storage device is provided, readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for vertical handoff in a wireless network. The method steps comprising monitoring a wireless local area network signal carrying an active network connection, initiating vertical handoff to a wireless wide area network signal upon determining that the wireless local area network signal is undesirable, tunneling the active network connection over the wireless wide area network signal, and caching and replaying information over the wireless wide area network signal. | 20040401 | 20070717 | 20050310 | 79731.0 | 2 | NGUYEN, THUAN T | SYSTEM AND METHOD FOR IP HANDOFF | SMALL | 0 | ACCEPTED | 2,004 |
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10,815,549 | ACCEPTED | Methods and apparatus for controlling bandwidth and service in a communications system | Methods and apparatus for performing admission control and bandwidth allocation from a centralized network location in a communications system which supports various IP based services are described. Admission control is performed based on user interaction with a Web interface hosted by a centralized control. Users may subscribe/unsubscribe to premium (e.g., high bandwidth) services. Admission control to the premium services is controlled by the centralized control. The control interfaces with a gateway (edge) router which implements service decisions. The centralized control maintains a database of the users, links in the network, network elements, and estimates of allocated/free bandwidth on the links. In some embodiments, traffic, not under centralized control, e.g., from business switches and/or legacy gateway routers may be injected onto the network links. Load estimation methods are used to account for bandwidth consumed on the links by this injected traffic. | 1. A centralized method of providing admission control functionality in a communications system including a plurality of nodes, said plurality of nodes including a control node, at least a first node coupled to a second node by a first link, a third node coupled to the second node by a second link and a fourth node coupled to the third node by a third link, together by communications links connected together by links, the method comprising: maintaining a set of link bandwidth utilization information, the set of link bandwidth utilization information including bandwidth utilization statistics for at least each of the first, second and third nodes; and operating the control node to receive a service request corresponding to the first node and to determine from said maintained set of link bandwidth utilization information if there is sufficient bandwidth available on at least said second and third links to satisfy said service request. 2. The method of claim 1, further comprising: when it is determined from said maintained set of link bandwidth utilization information that there is sufficient bandwidth available to satisfy said service request: operating the control node to signal at least one of said first, second, third and fourth nodes that said service request has been granted; and operating the control node to update link bandwidth utilization statistics for at least two of said first, second and third links to reflect bandwidth that will be utilized by the requested service that was granted. 3. The method of claim 1, further comprising: operating the control node to generate the link bandwidth utilization information corresponding to said second link from an estimate of bandwidth that will be used on said second link by services over which said control node does not have admission control and a sum of services which will used said second link which said control node authorized. 4. The method of claim 3, wherein said link bandwidth utilization information corresponding to said second link is further generated as a function of a link utilization scaling factor. 5. The method of claim 4, wherein best effort Internet traffic is carried over said second link and where said link bandwidth utilization information corresponding to said second link is further generated as a function of the physical link capacity of links used to couple Internet service users to said second link and an average of the physical link capacity which is used over a period of time by said users for Internet service. 6. The method of claim 5, wherein said control node generates a control message to reduce the amount of bandwidth allocated to best effort traffic on one of said first, second and third links, when a service request for a service requiring a guaranteed amount of bandwidth on said one of said first, second and third links is received and said guaranteed amount of bandwidth is not available due to best effort traffic on said one of said first, second and third links. 7. The method of claim 1, further comprising: when it is determined from said maintained set of link bandwidth utilization information that there is insufficient bandwidth available to satisfy said service request; and determining if a user to whom said service request corresponds is using other services which can be terminated to provide the bandwidth required to satisfy said service request. 8. The method of claim 7, further comprising: when it is determined that said user to whom said service request corresponds is not using other services which can be terminated to provide the bandwidth required to satisfy said service request, operating the control node to send a messagedenying said service request. 9. The method of claim 7, further comprising: when it is determined that said user to whom said service request corresponds is using other services which can be terminated to provide the bandwidth required to satisfy said service request, presenting the user with the operation of terminating the services being provided to said user which can be used to provide the bandwidth required to satisfy the service request. 10. The method of claim 9, further comprising: operating the control node to receive a reply from said user indicating a desire to terminate services or not to terminate services; and denying said service request when said reply indicates a desire not to terminate services; and granting said service request when said reply indicates a desire to terminate services. 11. The method of claim 10, where said step of granting said service request includes: operating the control node to terminate at least some services provided to said user and to reallocate at least some of the bandwidth used by said services to providing the requested service. 12. The method of claim 10, wherein presenting the user with the operation of terminating the services includes: providing information to said user through a web interface indicating which services are available for termination. 13. A communications system comprising: a first node; a second node coupled to the first node by a first link; a third node coupled to the second node by a second link; a fourth node coupled to the third node by a third link; and a control node coupled to at least one of said first, second, third, and further nodes, said control node including and maintaining a set of link bandwidth utilization information, the set of link bandwidth utilization information including bandwidth utilization statistics for at least each of the first, second and third nodes; said control node further including: means for receiving a service request corresponding to the first node and to determine from said maintained set of link bandwidth utilization information if there is sufficient bandwidth available on at least said second and third links to satisfy said service request. 14. The system of claim 13, wherein said control node further includes: means for signaling at least one of said first, second, third and fourth nodes that said service request has been granted when it is determined from said maintained set of link bandwidth utilization information that there is sufficient bandwidth available to satisfy said service request:; and means for updating link bandwidth utilization statistics for at least two of said first, second and third links to reflect bandwidth that will be utilized by the requested service that was granted. 15. The system of claim 13, wherein said control node further comprises: means for generating link bandwidth utilization information corresponding to said second link from an estimate of bandwidth that will be used on said second link by services over which said control node does not have admission control and a sum of services which will used said second link which said control node authorized. 16. The system of claim 15, wherein said link bandwidth utilization information corresponding to said second link is further generated as a function of a link utilization scaling factor. 17. The system of claim 16, wherein best effort Internet traffic is carried over said second link and where said link bandwidth utilization information corresponding to said second link is further generated as a function of the physical link capacity of links used to couple Internet service users to said second link and an average of the physical link capacity which is used over a period of time by said users for Internet service. | FIELD OF THE INVENTION The present invention relates generally to the field of communications systems and, more particularly, to the field of user access, e.g., admission control procedures, and bandwidth allocation suitable for use in, e.g., system which provide DSL (digital subscriber line) services. BACKGROUND OF THE INVENTION Currently, DSL services are normally offered as best effort services without any guarantees, e.g., with regard to end to end data rates (bandwidth) that will be provided. Such best effort services cannot support products that require certain specific guaranteed levels of bandwidth and/or quality of service (QoS) which may be expressed in terms of latency, jitter and/or packet loss. Products which require bandwidth and/or QoS guarantees include, for example VoIP, Video RT, or gaming. Products that require particular levels of guaranteed bandwidth and/or QoS guarantees are usually more expensive products then best effort products, e.g., basic Internet Access. Accordingly, DSL providers may increase their profits or increase the attractiveness of its offer in cases where they can provide a customer with various service guarantees. Existing DSL architectures may control access and bandwidth based on ATM service classes but such implementations tend to be very expensive to implement and generally cannot be used ad-hoc or on request. In addition they are generally fixed type implementations that do not allow for flexible bandwidth allocation policies based on the particular user making the request in combination with the type of service being requested. Providing bandwidth guarantees in a DSL network is complicated, particularly in the case of an existing system, by the difficulty to predict and/or control traffic on a network link. In existing DSL networks, portions of the networks often include traffic from outside sources, not under the control of the local service provider. These outside sources may inject traffic onto the local network consuming bandwidth. Given that the local service provider normally can not directly control such loads or know the actual load from such sources with certainty at any particular time, there is a need for taking such loads into consideration when deciding on whether to admit or deny requests for services. In view of the above discussion, it should be appreciated that there is a need for load estimation methods for the links in DSL networks which could be used to efficiently estimate link utilization and control link utilization so that the capacity of each link in a network is utilized in an efficient manner. Known approaches to varying user data rates include applying distributed load estimation methods. In such known methods, the admission control is distributed throughout the system, and decisions for a positive admission of a user to a higher level of service (e.g., more bandwidth) are evaluated by many elements (e.g., multiple routers, switches, DSLAMs, etc.) along the communications flow path. Each element performing an evaluation needs to give a positive decision for admission and/or more bandwidth allocation to a user. One such known method used to implement distributed load estimation involves RSVP (Resource Reservation Protocol). In the case of RSVP, the node to which each link along a communications path corresponds makes a separate determination as to whether the requested session will exceed link capacity. If any one node along a path determines it does not have the capacity to satisfy a session request, the request will be denied. Current implements of RSVP in DSL networks have been problematic and difficult to implement. Accordingly, there is a need for an alternative method to take into consideration link capacity and make admission control/service decisions based on available capacity. In light of the above discussion, there is a need for improved methods of admission control and bandwidth allocation in communications networks, e.g., networks which provide different types of services over DSL and other types of lines to subscribers. Methods of admission control and bandwidth allocation that utilize a centralized control method, as opposed to a distributed control method, could be beneficial. Methods that allow for users to request and relinquish various levels of premium (e.g., high bandwidth) services dynamically would be particularly desirable. It would be beneficial if at least some of the new methods allowed a user to dynamically terminate sessions/services to free up bandwidth need to satisfy a request by the user. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 illustrates an exemplary DSL communications system implemented in accordance with the present invention. FIG. 2 illustrates an exemplary method of bandwidth estimation for communication links in accordance with the present invention. FIG. 3 illustrates a more detailed representation of an exemplary Service Deployment System (SDS) that may be used in the system of FIG. 1, implemented in accordance with the present invention. FIG. 4 illustrates a more detailed representation of an exemplary Lightweight Directory Access Protocol (LDAP) database that may be used in the Service Deployment System of FIG. 3, implemented in accordance with the present invention. FIG. 5 shows a flowchart illustrating an exemplary method of controlling the user access and bandwidth allocation in DSL service, in accordance with the present invention. FIG. 6 shows a flowchart illustrating a method of an exemplary admission control method, in accordance with the present invention. SUMMARY OF THE INVENTION The present invention is directed to methods and apparatus for supporting flexible and/or reliable service request control decisions, e.g., flow admission requests decisions, in a communications system, e.g., a communications system which supports IP based services through the use of one or more DSL connections. Various features of the invention are directed to improved methods for tracking and estimating the bandwidth on each of the links in the local DSL network thereby supporting better and/or more efficient utilization of the available bandwidth on each of the links when such information is used in combination with the centralized service control features of the invention. Such link bandwidth tracking methods include methods used to account for injected traffic not under the control of the local network. Service/admission control decisions correspond to bandwidth allocation decisions since bandwidth is utilized by granted requests for services and/or admitted flows. Admitted flows may correspond to IP packet and/or ATM cell flows corresponding to a requested service or communications session. Bandwidth monitoring and service request/admission control decisions are made within a network with regard to one or more communications links, e.g., router connections, from a centralized location. Flows on different links are monitored. Link traffic information is communicated to a centralized location, a control node in the form of a service control system sometimes called referred to as a Service Deployment System (SDS. The centralized location keeps track of different service requests, granted requests, and the amount of bandwidth required by the granted requests. Estimates of best effort traffic, e.g., Internet traffic, over various links are generated and maintained. For premium services with a guaranteed level of bandwidth, that is known to the SDS, the guaranteed bandwidth is taken into consideration when calculating a traffic load on links over which traffic corresponding to a requested service request/admission control request will flow. Estimates of the effect of traffic over which the SDS does not have control are made and factored into estimates of available bandwidth on the links in the system. Service requests, which may be in the form of admission control requests, are communicated to the SDS from various nodes. The SDS takes into consideration the type of service being requested and the availability of bandwidth required to service the requests on links in the network. Before granting a request, the SDS determines whether there is available bandwidth on the links which will be affected by the request based on the known link load information, estimated link load information and, in some cases, one or more scaling factors. In the case where there is a single bottleneck node, e.g., a node which represents the most constrained part of the communications path over which packets will flow, the decision to grant or deny a service request may be made based on whether or not the necessary bandwidth is determined to be available on the bottleneck node. In accordance with one feature of the present invention, the SDS may respond to a service request when there is insufficient capacity to grant the request on a link by adjusting the load on the link, e.g., by reducing the amount of best effort traffic allowed to pass over the link. Such adjustments may be made, e.g., by a router coupled to the link, based on control information provided by the SDS. In accordance with another feature of the present invention, when the SDS determines that there are insufficient resources on a link to service a request, the SDS will check to determine if the user making the request has one or more active services which are using resources on the congested link. Assuming that the requesting user is utilizing sufficient resources on the congested link that, if released, would make the requested service possible, the user is presented with the chance to terminate the ongoing services and have the resources reallocated to servicing the user's current request. If the user indicates a willingness to terminate the sessions consuming the resources on the congested link the SDS terminates the services and the grants the user's request for the new service. The methods and apparatus are particularly well suited for a hierarchical service system where higher priority, e.g., premium services, are given priority over lower priority, e.g., best effort, services. To avoid best effort traffic being denied completely, at least some bandwidth may be reserved on a link for best effort traffic even in cases where traffic having a higher priority may seek to use a link. While the methods and apparatus of the present invention are described in the context of system where DSL links are used to connect at least some end user systems to network nodes, the methods and apparatus of the present invention with centralized link load estimation and admission control are well suited for a wide variety of networks where different types of service with differing quality levels may be required and/or where there is a need to support a hierarchy of services with limited communications resources. While admission control may depend on the availably of sufficient bandwidth on one or each link to be used to provide a service, by centralizing the service/admission control process, significant savings in overhead may be achieved. Noticeable improvements may be achieved as compared to RSVP or other approaches where each node involved in providing a service is responsible for making a decision as to whether or not a service request should be granted and the end decision depends on the combination of decisions by several individual nodes. Numerous additional features and benefits of the methods and apparatus of the present invention are discussed below in the detailed description which follows. DETAILED DESCRIPTION The present invention is directed to methods and apparatus for supporting flexible and/or reliable service request/admission control decisions in a communications system, e.g., a communications system which supports IP based services through the use of one or more DSL connections. The service/admission control decisions correspond to bandwidth allocation decisions since bandwidth is utilized by granted requests for services and/or admission of flows, e.g., as part of establishing a communications session or providing a service. A DSL communications system, implemented in accordance with the present invention, may use a Vertical Services Domain (VSD) architecture or other hierarchical architecture service structure. FIG. 1 illustrates an exemplary DSL communications system 100 using apparatus implementing the methods of the present invention. Communications system 100 includes a Service Deployment System (SDS) 102, a gateway router (GWR) (R1) 104, an Advanced Digital Network Asynchronous Transfer Mode (ADN ATM) Switch (S1) 106, a plurality of Digital Subscriber Line Access Multiplexers (DSLAMs): (DSLAM 1 (D1) 108, DSLAM 2 (D2) 110), a plurality of Asymmetric Digital Subscriber Line (ADSL) Termination Units—Remote (ATU-Rs): (ATU-R1 (A1) 112, ATU-R2 (A2) 114, ATU-R3 (A3) 116, ATU-R4 (A4) 118, and a plurality user devices, e.g., personal computers, (PC1 120, PC2 122, PC3 124, PC 4 126, PC 5 128, PC 6 130). The SDS 102 is coupled to gateway router (R1) 104 via link 132. Gateway router (R1) 104 is coupled to ADN ATM switch S1 106 via link L(S1,R1) 134, and ADN ATM switch (S1) 106 is coupled to DSLAM (D1) 108 via link L(D1,S1) 136; gateway router (R1) 104 is also coupled to DSLAM (D2) 110 via link L(D2,R1) 138. DSLAM (D1) 108 is coupled to ATU-R (A1) 112 and ATU-R (A2) 114 via links L(A1D1) 140, L(A2,D1) 142, respectively. DSLAM (D2) 110 is coupled to ATU-R (A3) 116 and ATU-R (A4) 118 via links L(A3D2) 144, L(A4,D2) 146, respectively. ATU-R (A1) 112 is coupled to PC 1 120 and PC 2 122 via links, 148, 150, respectively; ATU-R (A2) 114 is coupled to PC 3 124 via link 152. ATU-R (A3) 116 is coupled to PC 4 126 and PC 5 128 via links 154, 156, respectively; ATU-R (A4) 118 is coupled to PC 6 130 via link 158 coupled together as shown in FIG. 1. Service Deployment System (SDS) 102 (sometimes alternately referred to as a Service Selection Center (SSC)) is the central point in the system 100 for processing user (e.g, ATU-R A1 112) requests for change in service levels (e.g., add a premium service) and making admission control decisions via its admission control routine 199. SDS 102 tracks how much bandwidth is available on the links between the GWR R1 104 and ATU-Rs 112, 114, 116, 118, and makes admission control decisions (denies/grants service, e.g., flow admission or communication session, requests). Gateway Router (R1) 104 (sometimes alternately referred to as an a provider edge router or a service router) is coupled to the SDS 102 and is responsive to service/admission control decisions made by the SDS 102 to admit deny requests for service and/or restrict bandwidth allocated to particular type of traffic, user or service. ADN ATM switch (S1) 106 located at an intermediate point between GWR (R1) 104 and DSLAM (D1) 108 couples non-VSD elements and traffic (outside the control of admission control routine 199) onto links carrying traffic for VSD users (e.g., link L (D1,S1) 136). These non-VSD elements may be part of existing legacy systems; and the bandwidth consumed by these non-VSD elements on the links managed by the SDS 102 is estimated in accordance with the methods of the invention. DSLAMs (e.g. D1 108) multiplex inputs from a plurality of VSD users (e.g., ATU-Rs A1 112 and A2 114) onto a link (e.g., L(D1,S1) 136). DSLAMs control and set data line rates (control bandwidth) on links between the ATU-Rs and the DSLAMs (e.g., L(A1,D1) 140). ATU-Rs (e.g., A1 112) are users in the VSD architecture and are under the control of the SDS 102. Each ATU-R (e.g. A1 112) is a modem, which operates as a VSD user. Each VSD user may request via a Web portal, hosted by the SDS 102, changes in service levels. Each VSD user (ATU-R) has a basic level of service provided plus the capability to request and relinquish premium levels of service. Each VSD user is coupled to a plurality of user devices (e.g., PC 1 120, PC 2 122). Such user devices, may include other devices other than the exemplary PCs illustrated, e.g., telephones, video conference equipment, data link devices, television display or recording devices, music devices, etc. Communications system 100 also includes a Business ADN ATM Switch (BS1) 160 coupled to a plurality of Data Terminal Equipments (DTEs) (DTE 1 162, DTE m 164) represented by m PVCs 179, and a Legacy Gateway Router (LR1) 166 coupled to a plurality of DTEs (DTE 1 168, DTE n 170) represented by n PVCs 183. Business ADN ATM Switch (BS1) 160 and Legacy Gateway Router (LR1) 166 are coupled to the ADN ATM Switch (S1) 106 via links 172, 174, respectively. Business ADN ATM Switch (BS1) 160 is coupled to DTE 1 162, DTE m 164 via links 176, 178, respectively. Legacy Gateway Router (LR1) 166 is coupled to DTE 1 168, DTE n 170 via links 180, 182, respectively. DTE's may include non VSD users (e.g., a communication peer of A1 112) which may direct traffic consuming bandwidth over link L(D1,S1) 136 which does not transverse GWR (R1) 104. System 100 also includes a Network Configuration Manager (NCON) 184 and a plurality of workstations which may be implemented, e.g., as Alcatel ADSL Work Stations (Access Management Systems) AWSs (AMSs) 186, 188. NCON 184 is coupled to SDS 102 via link 190. AWS 186 is coupled to SDS 102 via link 192 and coupled to DSLAM 1 (D1) 108 via link 194; AWS 188 is coupled to SDS 102 via link 196 and coupled to DSLAM 2 (D2) via link 198. NCON 184 is a provisioning system used to maintain and provision the DSL system. The NCON 184 may include information on the equipment in the system, e.g. R1 104, S1 106, D1 108, D2 1110, BS1 160, LR1 166, information of links, information on users, and path details including information on the ATM cloud. In accordance with the invention, NCON 184 provisions the SDS 102's database with information (e.g., user IDs, user phone #, user base rate, use ports on routers and switches) to be used by admission control routine 199. In accordance with the invention, the SDS 102 periodically queries the AWSs 186, 188 to obtain information such as the users' sync rate. This information is indicative of the maximum data rate that can be communicated between the user and the DSLAM in the upstream and downstream directions. The AWSs 186, 188 interface with the DSLAMs D1 108, D2 110, respectively to retrieve the information from the DSLAMs and convey the information back to the SDS 102 for use in admission control decisions. System 100 further includes a cell relay 103, a Service Provider/Corporate Point of Presence (SP/Corporate POP) 105, and an SP/Corporate Network 107 including a communications peer 109. The Gateway Router (R1) 104 is coupled to cell relay 103 via link 111; cell relay 103 is coupled to SP/Corporate POP 105 via link 113; SP/Corporate POP 105 is coupled to SP corporate network 107 via link 115. Cell relay 103 may include a core and/or transport network. Cell relay 103 relays information, e.g., ATM packets, from/to Gateway Router (R1) 104. SP/Corporate POP 105 may be an interchange carrier's local central office. SP/Corporate network 107 may be a network controlled by a service provider other than the service provider operating the SDS 102, NCON 184, and Gateway Edge Router 104. The interconnectivity between Gateway Router R1 104 and communications peer 109 may enable connectivity between a VSD user (e.g., user A1 112) and a communications peer 109. Communications peer 109 may communicate information (e.g., high bandwidth data such as compressed data files of movies on demand) to a VSD user (e.g., A1 112) which has requested and been granted a premium level of service by the SDS 102. The VSD user request is normally generated in response to a request initiated by an actual human user operating a PC or other device coupled to the ATU-R. Admission control in the VSD architecture of system 100 (e.g., for user A1 112) is performed based on user interaction with a Web portal hosted by the Service Deployment System (SDS) 102. User requests for premium services (such as Coolcast or Intertainer streams) with QoS are made via this portal; in some cases, a customer can also go directly to a content provider's Web site to request content (bypassing the portal), but then the user will receive only best-effort service. The SDS 102 keeps track of the total bandwidth consumed by premium services with bandwidth guarantees in the following segments of the access network of system 100: 1. The link between the user's DSL modem (ATU-R) and the DSLAM, (e.g., link L(A1, D1) 140 between user A1 112 and D1 108); and 2. One or more links between the DSLAM and the Gateway Router, depending on the architectural variant of the link: a. In a “distributed” variant, there is a direct link (typically Digital Service, Level 3 (DS-3), although sometimes Optical Carrier-3 (OC-3)) between the DSLAM and the Gateway Router, (e.g., link L(D2,R1) 138 between D2 110 and R1 104); or b. In a “hubbed” variant, a DSLAM is coupled to the Gateway router by an intermediate device, e.g., an ATM switch which operates as a traffic hub. Consider for example ATM switch 106 which operates as a hub. In such a case there are multiple links, e.g., the link (typically DS-3) between the DSLAM and the optional ATM switch, (e.g., link L(D1,S1) 136 between D1 108 and S1 106), and the link (typically OC-3) between the optional ATM switch and the Gateway Router, (e.g., link L(S1,R1) 134 between S1 106 and R1 104). The calculation of total bandwidth consumed in segments (2a) or (2b) above involves a summation over the VSD users hosted on those segments. The information needed to perform this calculation is maintained by the SDS 102 in a database, e.g., a Lightweight Directory Access Protocol (LDAP) database. In order for a user request for a premium service to be granted, sufficient free bandwidth to support that service request should be available in each of the network segments (links) between the user (e.g. A1 112) and the Gateway Router (e.g. R1 104), otherwise the request is denied. If the request is denied, the user may be given the option of deactivating one of the user's currently-subscribed premium services in order to make that bandwidth available to satisfy the new service request. It is possible that there will be bandwidth consumed on the link between the DSLAM and the ATM switch (e.g. link L(D1S1) 136) in the hubbed variant that is not under the control of the admission control routine 199 and thus is not accounted for or controlled by the IP QoS policies at the Gateway Router (R1) 104. For example, as illustrated in FIG. 1, downstream traffic due to non-VSD services may be inserted at the ATM switch (S1) 106 on link L(D1,S1) 136 by a “legacy” Gateway Router (LR1) 166 (supporting neither VSD nor IP QoS), or by an ATM switch supporting the “Business ADN” service (BS1) 160 (i.e., business-grade DSL). In this situation, the following problems arise: 1. The admission control routine 199 of SDS 102 is not aware of the bandwidth being consumed by the non-VSD services, and thus the bandwidth is not directly accounted for in the admission control calculations. 2. In current (known) ADN architectures, the connection between the user (e.g. a modem such as A1 112) and the Gateway Router is a Unspecified, e.g, Undefined Bit Rate (UBR), Permanent Virtual Circuit (PVC) (i.e., providing no ATM QoS). Since the ATM switch (S1) 106 and DSLAM (D1) 108 do not support 1P QoS, there is no way to differentiate a user's premium service traffic from best effort traffic on these network elements. (PVCs from Legacy Gateway Routers (e.g., LR1 166) are also UBR.) 3. Business ADN service is supported by a “direct” Variable Bit Rate (VBR) PVC connection to the user, which provides a higher-priority ATM CoS than UBR (and thus potentially gives this traffic precedence over the VSD traffic). In order to provide a “work around” for these problems, the SDS 102 in accordance with the admission control method of the present invention attempts to indirectly account for the non-VSD traffic by using traffic engineering calculations as described below. For example, for the users A1 112 and A3 116, loads on the following network links will be taken into account, in various embodiments by the SDS 102 and its admission control routine 199. (DSLAM or ATM User ATU-R/DSLAM DSLAM/ATM Switch Switch)/GWR A1 112 L(A1, D1) 140 L(D1, S1) 136 L(S1, R1) 134 A3 116 L(A3, D2) 144 NULL L(D2, R1) 138 For User A3 116 (the distributed variant, without the optional ATM switch), all traffic on the two links 144, 138 involved is under the control of the Gateway Router (R1) 104; thus, no “work around” or “engineering traffic estimation” calculations are necessary since the traffic load can be accurately determined from the available admission information. However, for User A1 112 (the hubbed variant, with an ATM switch (S1) 106 between the DSLAM (D1) 108 and Gateway Router (R1) 104), the load on link L(D1,S1) 136 may be problematic due to unaccounted loads on this link from Business ADN switch (BS1) 160 and/or Legacy Gateway Router (LR)1 166. The total load on this link includes three factors: Total-Load(L(D1,S1))=VSD-Load(L(D1,S1))+BusinessADN-Load(L(D1,S1))+LegacyGWR-Load(L(D1,S1)) (Equation 1) The values of these three factors may be computed as follows. The VSD-Load on a link is known by the SDS 102, via summing the admitted VSD services of each of the VSD users currently active on that link, plus the observed “average” maximum utilization of Internet service for each of the provisioned subscribers (both “pure PTA (Point to Point Protocol Termination and Aggregation)” and L2TP (Layer 2 Tunneling Protocol)) on the link. An observed “high estimate” of the maximum utilization of Internet service in a current best-effort known DSL network is 20 Kbps per provisioned user. That value of 20 kbps per provisioned user may be used as the observed “average” maximum utilization of Internet service for each of the provisioned subscribers, in some embodiments of the present invention. The maximum value of the BusinessADN-Load on a link may be determined via summing the configured Peak Cell Rates of each of the VBR PVCs provisioned on the link. The maximum value of the LegacyGWR-Load on the link L(D1,S1) 136 due to the Legacy Gateway Router (LR1) 166 may be estimated via: LegacyGWR-Load(L(D1,S1))=NPVC(LR1)·MaxLoadPVC(LR1) where NPVC(LR1) is the number of PVCs provisioned on link L(D1,S1) 136 by LR1 166, and MaxLoadPVC(LR1) is the maximum load per PVC on LR1. Note that MaxLoadPVC(LR1) is itself an estimated value. In some embodiments of the invention, the MaxLoadPVC value will be provisioned. In other embodiments, utilization of the PVCs is monitored, and the utilization information is used to increase the accuracy of the estimated MaxLoadPVC value. This monitoring may either be active (e.g., via Response Timer Response (RTR) probes) or passive (e.g., via accessing bulk performance statistics from the DSLAM (D1) 108 and/or ATM switch (S1) 106). Since Equation 1 relies on maximum load estimates for the Business ADN and Legacy Gateway Router loads, the use of Equation 1 may lead to underutilization of the link L(D1,S1) 136. Thus, it is desirable to utilize “scaling factors” to tune the load estimates based on traffic engineering estimates, as in Equation 2. (See, e.g., N. Giroux and L Ganti, Quality of Service in ATM Networks, Prentice Hall-PTR, 1999, pp. 90ff included herein by reference which describes the use of scale factors in load estimation) Total-Load(L(D1,S1))=VSD-Load(L(D1,S1))+SBADN·BusinessADN-Load(L(D1,S1))+SLR·LegacyGWR-Load(L(D1,S1)) (Equation 2) where SBADN is the Scaling factor for Business ADN load, and SLR is the Scaling factor for the Legacy Gateway Router load. Both scaling factors are real values between 0 and 1. FIG. 2 is a flowchart 200 illustrating a bandwidth usage estimation method for a link, e.g., between an ADN ATM switch and a DSLAM (e.g. link L(D1,S1) 136 between S1 106 and D1 108) as described above, in accordance with the invention. The bandwidth link estimation method is started in step 210. In step 210, the link to be evaluated is identified; VSD users (ATU-R modems) of the link are identified; the DSLAM and ADN ATM switch connecting to the link are identified; any Business ADN ATM Switches and/or Legacy Gateway Routers connected to the ADN ATM switch are also identified. Information may also be obtained or retrieved (e.g., from a database and/or measurement probes ) in step 210 regarding the elements identified, e.g., activity, service levels, max rates, utilization rates, provisioning information, estimated rates, tuning values, etc. Operation proceeds from step 210 to three steps 220, 230, and 240. In step 220, the current estimated VSD load on the link (e.g. L(D1S1) 136) is calculated. Step 220 includes sub-step 222 and sub-step 224. In sub-step 222, the load for the admitted VSD services (e.g., premium services) for the VSD users currently active on the link are summed. For example, user A1 112 may be active and may have been admitted to one VSD services each with a first BW allocation; user A2 114 may also be active and may have been admitted to two VSD services each with a second and third bandwidth allocation, respectively. The VSD bandwidth is summed from those three services. Operation proceeds from sub-step 222 to sub-step 224. In sub-step 224, the average maximum utilization of internet service (best effort DSL service) for the provisioned subscribers on the link (e.g., 20 Kbps/user×2 users=40 Kbps) is added to the result of step 222. The average may be for a pre-determined time period. In step 230, the current estimated Business ADN load on the link (e.g. L(D1S1) 136) is calculated. Step 230 includes sub-step 232 and sub-step 234. In step 232, a maximum load on the link due to the Busisness ADN ATM Switch (e.g. BS1 160) traffic is determined by summing the configured peak cell rates of the VBR PVCs provisioned on the link. Then in step 234, the current business ADN load is tuned by multiplying, the value of step 232 by a scale factor for the business ADN (e.g., a value between 0 and 1). In step 240, the current estimated Legacy Gateway Router load on the link (e.g. L(D1S1) 136) is calculated. Step 240 includes sub-step 242 and sub-step 244. In step 242, a maximum load on the link due to the Legacy Gateway Router (e.g. LR1 166) traffic is determined by multiplying the number of PVCs provisioned on the link by the legacy GWR by the maximum load per PVC on the legacy GWR. Then in step 244, the current legacy gateway router load estimate is tuned by multiplying, the value of step 242 by a scale factor for the legacy gateway router (e.g., a value between 0 and 1). In step 250, the bandwidth estimates from step 220 (VSD load estimate), step 230 (Business ADN load estimate), and step 240 (Legacy GWR load estimate) are summed to obtain an overall link (e.g. L(D1,S1) 136 ) estimate. In step 260, the bandwidth link estimate is output for use, e.g., by the admission control routine 199 in SDS 102. FIG. 3 illustrates an exemplary Service Deployment System (SDS) 300, implemented in accordance with the present invention. SDS 300 may be used as SDS 102 in exemplary system 100 of FIG. 1. SDS 300 includes a Web Portal 302, an I/O interface 304, a CPU 306, and a memory 308 coupled together via a bus 310 over which the various elements may interchange data and information. Memory 308 includes routines 312 and data/information 314. Data/information 314 includes a LDAP (Lightweight Directory Access Protocol) database 338 and data 340. LDAP (v3) is described in publicly available RFC-2251 titled: Lightweight Directory Access Protocol (v3) which can be obtained from the IETF website at: http://www.ietf.org/rfc/rfc2251.txt. Routines 312 include a global initialization routine 316, a monitoring routine 318, a user log-in routine 320, a user change request routine 322, SDS control routines 324, communications routines 326, and an admission control routine 328. Web portal 302 provides an interface to the user, e.g. ATU-R1 (A1) 112, through which VSD admission control information may be conveyed between VSD users, e.g., modems such as A1 112 and SDS 300. Information regarding VSD user: log-in, log-out, requests for premium services, requests for relinquishing premium services may be conveyed via Web Portal 302. In addition SDS options for relinquishing currently active VSD premium user service(s) in order to accommodate a newly requested VSD premium service may be conveyed via Web Portal 302. I/O interface 304 provides a network interface to a gateway router (e.g., R1 104) through which VSD user information and control information flows. VSD user information includes information about a user's current services as well service requests, e.g., information pertaining to change request made in an attempt to change VSD service levels. Control Information includes information to notify the gateway router (e.g. R1 104) of service grant decisions (admission control decisions) by the SDS 102 so that the gateway router (e.g. R1 104) can make adjustments in best effort traffic as may be required to support a service grant decision, e.g., a decision to provide a service requiring a guaranteed amount of bandwidth. I/O interface 304 also includes an interface (e.g., to a secure service provider control network) to NCON 184 and AWSs 186, 188 for information flows to obtain information used for VSD admission control. NCON 184 may provision the LDAP database 338 through interface 304 with data/information (e.g., user base rate, user phone#, user I/D, user ports). Alternately, or in addition, SDS 300 may retrieve data/information from NCON 184 and save data/information in LDAP database 338. In some embodiments, SDS 300 may also send data/information to NCON 184 through I/O interface 304. SDS 300 periodically queries the AWSs 186, 188 to receive DSLAM information, (e.g., user's sync rates). CPU 306 executes the routines 312 and uses the data/information 314 in memory 308 to control the operation of SDS 300 including monitoring bandwidth usage and/or estimated usage on the links under SDS VSD control, processing admission control requests, making admission control decisions, and implementing admission control decisions. Global initialization routine 316 initializes the SDS 300 when the SDS 300 is powered on. Such initialization may include starting with no VSD premium services provided and setting available bandwidth for each user link tracked by SDS 300 to a default value based on the number of users and per user internet BW. Monitoring routine 318 uses web portal 302 and monitors for input including VSD user log-ins and VSD service requests for change. Monitoring routine 318 monitors for user input. Monitoring routine 318 evokes user login routine 320 and/or user change request routine 324 in response to detected user input. User log in routine 320 identifies a VSD user, e.g., A1 112, identifies the pre-provisioned VSD premium services for that user, and evokes the admission control routine 328 for each of those pre-provisioned VSD premium services identified. User change request routine 322 identifies a user, e.g., A1 112, and identifies a request for a change in service, e.g., add a new service, drop a service, or log-out. User change request routine 322 evokes admission control routine 328 for each requested change in service. SDS control routines 324 control basic SDS 300 operation and functionality including the operation of the I/O interface 304. SDS control routines 324 also perform timing control and control the generation, transmission, and reception of message signaling to other elements in system 100, e.g., NCON 184, AWSs 186, 188, and R1 104. Communications routines 326 includes communications protocols used by SDS 300 including Lightweight Directory Access Protocol (LDAP) used for the database 338 and Structured Query Language (SQL) used for communication flows with AWSs 186, 188. Admission control routine 328 is a more detailed representation of admission control routine 199 of FIG. 1. Admission control routine 328 controls the admission to VSD premium services for VSD users (e.g., ATU-R1 A1 112). Admission control routine 328 includes a request processing module 330, an unsubscribe module 332, and a subscribe module 334 including a user options module 336. Request processing module 330 receives a request for a change, determines the path (e.g., links including direction information) affected, and determines whether the request is a request to subscribe to a new service or an unsubscribe request from a currently subscribed service. Unsubscribe module 332 executes an unsubscribe of a service including signaling information and updating (e.g., updating available BW for each link affected, updating user current services, etc.). Subscribe module 334 determines whether a requested service can be granted, grants or denies the new service, and adjusts the available BW on each link affected (if granted). User options module 336 provides options to users, if the requested new service cannot be granted due to insufficient bandwidth. User options module 336 determines if the user may relinquish a currently subscribed service to free sufficient BW on the links to allow the new service to be granted, and offers the options available to the user. LDAP database 338 stores information on the links, scale factors, service rates, user BW, and VSD user records. LPAD database 338 information is used by admission control routine 328 when making admission control decisions. Data 340 may include intermediate data used by the SDS in performing calculations used for admission control, e.g., bandwidth estimation calculation on links. FIG. 4 illustrates a more detailed representation of an exemplary Lightweight Directory Access Protocol (LDAP) database 400 that may be used in the Service Deployment System (SDS) 300 of FIG. 3 as exemplary LDAP database 338. LDAP database 400 is implemented in accordance with the present invention. LDAP database 400 includes links table information 402, Business ADN ATM Switch Scale Factor (BADN SF) 404, Legacy Gateway Router Scale Factor (Legacy GWR SF) 406, service rates table information 408, per user Internet bandwidth information 410, VSD user record information 412, link information 414, and request information 416. Links table information 402 is a data structure with entries for each link in the local VSD network. In exemplary system 100, links table information includes entries for links 140, 142, 136, 134, 138, 144, and 146. Link table information 402 includes a plurality of link information entries, e.g., link (1, 2) information entry 418, link (X, Y) information entry 420. The indicies for each link information entry 418, 420 identify the network elements on each end of the link. For example, consider link L(D1,S1) 136 of FIG. 1; assume that element D1 108 is designated element #1 and element S1 106 is designated element #2, link L(D1,S1) 136 is represented by link(1,2) information entry 418. Exemplary link (1,2) information entry 418 includes link speed 422, available bandwidth 424, port 1 identification 426, port 2 identification 428, business ADN load 430, legacy gateway router (GWR) load 432, and number users 434. Link speed 422 is the provisioned rate of the link available for IP services. The units of link speed 422 are Kbps. Available Bandwidth (Avail BW) 424 is the bandwidth currently available on the link for new services; initially Avail BW 424 is equal to link speed 422. Port 1 ID 426 is the “originating” port on network element 1. Port 2 ID 428 is the “terminating” port on network element 2. Business ADN load 430 is the estimated bandwidth consumed on this link due to the load from business ADN switches (e.g., BS1 160). The units of business ADN load 430 are Kbps. Business ADN load 430 may be zero for some links, e,g, links 196, 144, and 146 of FIG. 1. Legacy Gateway Router (GWR) Load 432 is the estimated bandwidth consumed on this link due to load from legacy gateway routers, e.g., LR1 166. Legacy GWR load 432 may be zero for some links, e.g., links 196, 144, and 146 of FIG. 1. Number users 434 is the number of users provisioned on the link, including L2TP, PTA/L2TP, and “pure PTA” users. Note: If there is no link between the two elements A and B, the value (load) of Link(A,B) is NULL (0). Different load scale factors are often used for different services and/or links. Accordingly, one or more individual scale factors are often stored for each link Business ADN Scale Factor (BADN SF) 404 is a scaling factor for Business ADN load estimation adjustment calculations and is between 0 and 1. Legacy GWR SF 406 Scale is a Scaling factor used for Legacy Gateway Router load estimation adjustment calculations and is between 0 and 1. Service rates table information 408 is table of default bandwidth rates for each of a plurality VSD services available, e.g., service 1 bandwidth 436, service N bandwidth 438, in Kbps. The default bandwidth for service S is denoted by service(S) bandwidth. Per user Internet bandwidth information 410 is an estimate of the “average” maximum Internet utilization per provisioned user. Per user Internet bandwidth information may be initially set to 20 Kbps. In some embodiments, value 410 is adjusted, e.g., periodically, based on actual and/or estimated system measured usage information. VSD user record information 412 includes a plurality of VSD user records for each VSD user, e.g., VSD user 1 information 444, VSD user N information 446. VSD user record information 412 includes a data structure for each VSD user in the local VSD network. Each VSD user information, e.g., VSD user 1 information 444, includes a user ID 448, a user base rate 450, a user phone number 452, a user synchronization rate 454, user links 456, user default services 458, and user current services 460. User ID 448 identifies the user's PVC. User base rate 450 is a tier rate for shaping; the units of user base rate 450 are Kbps in the exemplary embodiment. User phone number 452 identifies shelf and slot of user's port in a DSLAM. User sync rate 454 (in Kbps) is the physical rate of the user's DSL line. Note that user sync rate 454 may differ from the link speed 422 of the user's DSL line in the links table information 402, since link speed 422 is defined in terms of bandwidth available at the IP layer. User links 456 is a list of the links along the user's data path from the ATU-R to the Gateway Router. In some embodiments, user links 456 may include pointers to structures in the links table information 402. User default services 458 is a list of the user's default (pre-provisioned) services. Each element in the list is a value indicating the service and the bandwidth required by the service. User current services 460 is a list of the user's currently subscribed services. Initially user current services 460 is the same as user default services 458, but user current services is updated as the user subscribes/unsubscribes to new services. Link information 414 includes a plurality of local variables, e.g., link (1,2) free bandwidth 462, link (X,Y) free bandwidth 464. Each value, e.g., link (1,2) free bandwidth is the computed free bandwidth currently available on a link. When processing a user request for a new service, the admission control routine 328 may determine which links are affected, calculate the free bandwidth for each link affected, and compare the free bandwidth for each link to the new (requested) service bandwidth rate to make admission decisions. Request information 416 includes requesting user 466, requested service 468, and service load information 470. Requested information 416 may be input through web portal 302. Requested information 416 may be passed to the admission control routine 328, when the admission control routine 328 is evoked. Requesting user 466 is the index of the requesting user's VSD user record information 412. Requested service 468 is the type of service being requested. Service load information 470 is the bandwidth required by the requested service 468 in Kbps. If the invoking procedure does not know the actual bandwidth required, it may invoke the admission control routine 328 with the default bandwidth for requested service 468 from the service rates table information 408. If service load information 470 is less than or equal to zero, requested service 468 is to be unsubscribed for the user. FIG. 5 is a flowchart 500 illustrating an exemplary method to control the user access and bandwidth allocation in DSL service in accordance with the present invention. In step 502, the method is started, e.g., when system 100 is powered on and/or reinitialized. Operation proceeds to step 504 in which global initialization is performed. In step 504, the LDAP database 400 is established; NCON 184 provisions the LDAP database 400 with information including VSD user record information 412, BADN SF 404, legacy GWR SF 406, Service Rates Table information 408, per user Internet BW information 410, and links table information 418. For each link in the links table information 402 initial available BW is set, e.g., for link(1,2) info 418 available BW 424 is set equal to link speed 422−(number users 434)*(per user internet BW 410). In step 504 the estimated bandwidth usage over the links in the VSD controlled network has been established for regular user Internet service; the VSD users have not yet been admitted to premium VSD services. Operation proceeds to step 504. In step 504, monitoring routine 318 monitors for input, e.g., user log in information 508. The input may be received through web portal 302. When the monitoring routine 318 detects a user log in 508, the monitoring routine 318 evokes the user log-in routine 320. Operation proceeds to step 510. In step 510, user log in routine 320 identifies the user, accesses the VSD user record information 412, e.g., VSD user 1 information 444 including the user default services 458. For each pre-provisioned service listed in user default services 458, the user log-in routine evokes the admission control routine 328 and requests admission to a service. The admission control routine 328 processes the request and grants or denies service for the request in accordance with the methods of the invention. Now, the VSD logged-in user has been admitted to the pre-selected premium VSD services, where possible, and the estimated bandwidth over the links in the VSD controlled network has accounted for the admission of those premium services. In step 512, monitoring routine 512 continues to monitor for user input, e.g., a user request for a change in service 514. A user request for a change in service 514 may include a request to add a new service, a request to drop a service, or a request to log-out, e.g., a request to drop each of the currently subscribed VSD premium services. In some embodiments multiple user requests 514 may be input simultaneously. When monitoring routine 318 detects a user request for change in service 514, it evokes the user change request routine 322, which processes the request. The user change request routine 322 stores the user request information 514 in LDAP database request information 416. In step 516, the user change request routine 322 evokes the admission control routine 328 for each requested change in service. The admission control routine 328 processes the request and grants or denies service for the request in accordance with the methods of the invention. The method of controlling user access and bandwidth allocation ends in step 518. However, monitoring continues in step 506 for additional user log-ins 508 and in step 512 for additional user requests for change in service 514. FIG. 6 is a flowchart 600 illustrating an exemplary method of admission control that may be used by admission control routine 328 in accordance with the invention. The admission control method starts in step 602, e.g., where the admission control routine 328 is evoked by the user log-in routine 320 or the user change request routine 322. Next, in step 604, the request processing module 330 receives a request for change including request information 416. Operation proceeds to step 606, where request processing module 606 determines the path affected, and sets up link information entries 414 for each of the links along the affected path. Then, in step 608, the request processing module 330 determines if the desired change is an unsubscribe to a service or a subscribe to a new service. If the request is an unsubscribe of a service, operation proceeds to step 610 and control is transferred to the unsubscribe module 332. If the request is a subscribe of a new service, operation proceeds to step 616 and control is transferred to subscribe module 334. Assume for discussion purposes operation proceeds from step 608 to step 610. In step 610, unsubscribe module 332 grants the user an unsubscribe of a premium VSD service. The unsubscribe grant may be forwarded to the user via Web portal 302. Also the unsubscribe grant is forwarded to gateway router R1 104. In addition, the unsubscribed service may be removed from the user current services 460 entry in the user's VSD record (e.g., VSD user 1 info 444). In this manner the various devices are made aware that resources are being freed on the affected link. Operation proceeds from step 610 to step 612. In step 612, unsubscribe module 332, for each link affected, updates the available bandwidth 424 by adding the relinquished bandwidth (corresponding to the unsubscribed service) to the available bandwidth 424. Operation of the admission control routine 328 terminates in step 614. Assume operation proceeds from step 608 to step 616. In step 616 subscribe module 334 calculates the free bandwidth for each of the links that are affected if the new service is granted. For example, consider that link (1,2) was one of the links affected; Link (1,2) free BW 462=avail BW 424−(BADN SF 404*Business ADN Load 430)−(Legacy GWR SF 406*Legacy GWR Load 432). Next, in step 618, for each link affected, the free BW (calculated in step 616) is compared to the new service request bandwidth requirement. The new service request bandwidth requirement may be included in the service load information 470 or may be obtained from the service rates table information 408 based on the requested service specified in requested service 468. For example, link (1,2) free BW 462 may be compared to service load information 470; alternately free BW 462 may be compared to a service rate, e.g., service N BW 438 assuming the requested service is service N. In step 620 a check is performed as to whether the new service bandwidth requirement is less than the free bandwidth for each of the affected links. If the new service requirement is less than the free bandwidth for each of the affected links, sufficient resources exist to admit the new service; therefore, operation proceeds to step 622 where the request is accepted. Operation proceeds from step 622 to step 624, where for each link affected, the available bandwidth, e.g., avail BW 424, in the links table info 402 is updated by subtracting the new service BW from the available bandwidth. In addition, the user current services, e.g., user current services 460, is updated for the requesting VSD user. In step 626, the new service is made available to the user. The SDS 102 notifies the gateway router R1 104 of the admission control decision. In step 626, the SDS 102 also notifies the user, e.g., ATU-R1 A1 112 that the new premium VSD service requested has been granted and is now available. From step 626 operation proceeds via connecting node B 628 to end node 614. However, if the check in step 620 revealed that there is insufficient free BW on each of the links affected to support the new service, operation proceeds to step 630. In step 630 the request is rejected. Operation proceeds from step 630 to step 632. In step 632, a check is made of the user current services, e.g., access user current services information 460 if the user is VSD user 1. In step 634, subscribe module 334 determines whether the user requesting the new service has any current (premium) VSD services active. If there are no current services, operation proceeds to step 636. In step 636, the user is presented via web portal 302, with a warning that there is insufficient bandwidth to support the requested service. Next, in step 638, subscribe module 334 cancels the new service request. Operation proceeds from step 638 to end node 614 via connecting node B 628. In step 634, if it was determined that some user services exist for the requesting user, operation proceeds to step 640. In step 640, a check is performed to determine whether the requesting user has sufficient current services, which if relinquished, could meet the new service bandwidth requirements on the affected links. If there are insufficient current resources, operation proceeds to step 636. However, if there are sufficient current resources, operation proceeds from step 640 to step 642 (via connecting node C 654). In step 642, user options module 336 presents the user, via Web portal 302, with a list of the user current services and gives the user a choice of dropping a current service or canceling the new service request. In some embodiments, user option 336 module may present the user with bandwidth information for each service. In some embodiments, user options module 336 may present the user with the option of dropping multiple services. In some embodiments, user options module 336 may present the user with alternative scenarios that may be selected to obtain the bandwidth needed by the new requested service. The response from the user, via Web portal 302, is received in step 643 and evaluated in step 644 by user options module 336. If the user did not select to drop a current service, then operation proceeds to step 646, where the new service request is canceled. Operation proceeds from step 646 to end node 614 via connecting node B 628. However, if the user did select to drop a current service in step 644, operation proceeds to step 648. In step 648, unsubscribe module 332 grants the user an unsubscribe of a premium VSD service. The unsubscribe grant may be forwarded to the user via Web portal 302. Also the unsubscribe grant may be forwarded to gateway router R1 104, so that R1 104. In addition, the unsubscribed service will be removed from the user current services 460 entry in the user's VSD record (e.g., VSD user 1 info 444). Operation proceeds from step 648 to step 650. In step 650, unsubscribe module 332, for each link affected, updates the available bandwidth 424 by adding the relinquished bandwidth (corresponding to the unsubscribed service) to the available bandwidth 424. Operation proceeds from step 650 to step 616 via connecting node A 652. Additional BW on the links of the VSD network has been freed by the relinquished service(s). In step 620, the new values for free bandwidth are calculated. Operation proceeds from step 616 to step 618 as previously described. Various components, modules, software, databases, etc. in the exemplary DSL VSD system have been described in the application with respect to specific manufactures and trade names, such as, e.g., Alcatel modems/switches/test devices, etc.; however, the present invention is applicable to other DSL systems, e.g., systems using similar or alternative components, modules, software, databases, etc. In addition the various functions of the invention may be implemented using modules. Such modules may use hardware, software, and/or a combination of hardware software in accordance with the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>Currently, DSL services are normally offered as best effort services without any guarantees, e.g., with regard to end to end data rates (bandwidth) that will be provided. Such best effort services cannot support products that require certain specific guaranteed levels of bandwidth and/or quality of service (QoS) which may be expressed in terms of latency, jitter and/or packet loss. Products which require bandwidth and/or QoS guarantees include, for example VoIP, Video RT, or gaming. Products that require particular levels of guaranteed bandwidth and/or QoS guarantees are usually more expensive products then best effort products, e.g., basic Internet Access. Accordingly, DSL providers may increase their profits or increase the attractiveness of its offer in cases where they can provide a customer with various service guarantees. Existing DSL architectures may control access and bandwidth based on ATM service classes but such implementations tend to be very expensive to implement and generally cannot be used ad-hoc or on request. In addition they are generally fixed type implementations that do not allow for flexible bandwidth allocation policies based on the particular user making the request in combination with the type of service being requested. Providing bandwidth guarantees in a DSL network is complicated, particularly in the case of an existing system, by the difficulty to predict and/or control traffic on a network link. In existing DSL networks, portions of the networks often include traffic from outside sources, not under the control of the local service provider. These outside sources may inject traffic onto the local network consuming bandwidth. Given that the local service provider normally can not directly control such loads or know the actual load from such sources with certainty at any particular time, there is a need for taking such loads into consideration when deciding on whether to admit or deny requests for services. In view of the above discussion, it should be appreciated that there is a need for load estimation methods for the links in DSL networks which could be used to efficiently estimate link utilization and control link utilization so that the capacity of each link in a network is utilized in an efficient manner. Known approaches to varying user data rates include applying distributed load estimation methods. In such known methods, the admission control is distributed throughout the system, and decisions for a positive admission of a user to a higher level of service (e.g., more bandwidth) are evaluated by many elements (e.g., multiple routers, switches, DSLAMs, etc.) along the communications flow path. Each element performing an evaluation needs to give a positive decision for admission and/or more bandwidth allocation to a user. One such known method used to implement distributed load estimation involves RSVP (Resource Reservation Protocol). In the case of RSVP, the node to which each link along a communications path corresponds makes a separate determination as to whether the requested session will exceed link capacity. If any one node along a path determines it does not have the capacity to satisfy a session request, the request will be denied. Current implements of RSVP in DSL networks have been problematic and difficult to implement. Accordingly, there is a need for an alternative method to take into consideration link capacity and make admission control/service decisions based on available capacity. In light of the above discussion, there is a need for improved methods of admission control and bandwidth allocation in communications networks, e.g., networks which provide different types of services over DSL and other types of lines to subscribers. Methods of admission control and bandwidth allocation that utilize a centralized control method, as opposed to a distributed control method, could be beneficial. Methods that allow for users to request and relinquish various levels of premium (e.g., high bandwidth) services dynamically would be particularly desirable. It would be beneficial if at least some of the new methods allowed a user to dynamically terminate sessions/services to free up bandwidth need to satisfy a request by the user. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention is directed to methods and apparatus for supporting flexible and/or reliable service request control decisions, e.g., flow admission requests decisions, in a communications system, e.g., a communications system which supports IP based services through the use of one or more DSL connections. Various features of the invention are directed to improved methods for tracking and estimating the bandwidth on each of the links in the local DSL network thereby supporting better and/or more efficient utilization of the available bandwidth on each of the links when such information is used in combination with the centralized service control features of the invention. Such link bandwidth tracking methods include methods used to account for injected traffic not under the control of the local network. Service/admission control decisions correspond to bandwidth allocation decisions since bandwidth is utilized by granted requests for services and/or admitted flows. Admitted flows may correspond to IP packet and/or ATM cell flows corresponding to a requested service or communications session. Bandwidth monitoring and service request/admission control decisions are made within a network with regard to one or more communications links, e.g., router connections, from a centralized location. Flows on different links are monitored. Link traffic information is communicated to a centralized location, a control node in the form of a service control system sometimes called referred to as a Service Deployment System (SDS. The centralized location keeps track of different service requests, granted requests, and the amount of bandwidth required by the granted requests. Estimates of best effort traffic, e.g., Internet traffic, over various links are generated and maintained. For premium services with a guaranteed level of bandwidth, that is known to the SDS, the guaranteed bandwidth is taken into consideration when calculating a traffic load on links over which traffic corresponding to a requested service request/admission control request will flow. Estimates of the effect of traffic over which the SDS does not have control are made and factored into estimates of available bandwidth on the links in the system. Service requests, which may be in the form of admission control requests, are communicated to the SDS from various nodes. The SDS takes into consideration the type of service being requested and the availability of bandwidth required to service the requests on links in the network. Before granting a request, the SDS determines whether there is available bandwidth on the links which will be affected by the request based on the known link load information, estimated link load information and, in some cases, one or more scaling factors. In the case where there is a single bottleneck node, e.g., a node which represents the most constrained part of the communications path over which packets will flow, the decision to grant or deny a service request may be made based on whether or not the necessary bandwidth is determined to be available on the bottleneck node. In accordance with one feature of the present invention, the SDS may respond to a service request when there is insufficient capacity to grant the request on a link by adjusting the load on the link, e.g., by reducing the amount of best effort traffic allowed to pass over the link. Such adjustments may be made, e.g., by a router coupled to the link, based on control information provided by the SDS. In accordance with another feature of the present invention, when the SDS determines that there are insufficient resources on a link to service a request, the SDS will check to determine if the user making the request has one or more active services which are using resources on the congested link. Assuming that the requesting user is utilizing sufficient resources on the congested link that, if released, would make the requested service possible, the user is presented with the chance to terminate the ongoing services and have the resources reallocated to servicing the user's current request. If the user indicates a willingness to terminate the sessions consuming the resources on the congested link the SDS terminates the services and the grants the user's request for the new service. The methods and apparatus are particularly well suited for a hierarchical service system where higher priority, e.g., premium services, are given priority over lower priority, e.g., best effort, services. To avoid best effort traffic being denied completely, at least some bandwidth may be reserved on a link for best effort traffic even in cases where traffic having a higher priority may seek to use a link. While the methods and apparatus of the present invention are described in the context of system where DSL links are used to connect at least some end user systems to network nodes, the methods and apparatus of the present invention with centralized link load estimation and admission control are well suited for a wide variety of networks where different types of service with differing quality levels may be required and/or where there is a need to support a hierarchy of services with limited communications resources. While admission control may depend on the availably of sufficient bandwidth on one or each link to be used to provide a service, by centralizing the service/admission control process, significant savings in overhead may be achieved. Noticeable improvements may be achieved as compared to RSVP or other approaches where each node involved in providing a service is responsible for making a decision as to whether or not a service request should be granted and the end decision depends on the combination of decisions by several individual nodes. Numerous additional features and benefits of the methods and apparatus of the present invention are discussed below in the detailed description which follows. | 20040401 | 20090811 | 20051013 | 93766.0 | 0 | DUONG, CHRISTINE T | METHODS AND APPARATUS FOR CONTROLLING BANDWIDTH AND SERVICE IN A COMMUNICATIONS SYSTEM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,551 | ACCEPTED | Refrigeration system and components thereof | A refrigeration system having a container with at least two different temperature cooling zones separated by a divider. The divider has a wall and a partition spaced apart from each other. The partition has a heat transfer plate with a sheet with a heat transfer substance attached thereto. The refrigeration system may be cooled by a variable capacity compressor system having refrigeration and hot-gas defrost modes. The system is defrosted by circulation of gas therethrough. A controller may be engaged to and selectably operate the compressor system. | 1. A multi temperature zone refrigeration system comprising: a container with at least two different temperature cooling zones; a divider separating the at least two cooling zones, where the divider has a wall and a partition spaced therefrom to define a heat exchange chamber, the partition being formed of a heat transfer plate having a sheet and a heat transfer substance attached to the sheet; a compressor system having refrigeration and hot-gas defrost modes, where the compressor system is in communication with at least one of the cooling zones; and a controller functionally connected to the compressor system for selectably operating the compressor system. 2. The refrigeration system of claim 1 where the compressor system has a variable capacity compressor. 3. The refrigeration system of claim 1, where the compressor system comprises: a variable capacity compressor; a condenser; a heat exchanger; and, an evaporator, where the variable capacity compressor is connected to the condenser, the condenser is connected to the heat exchanger, the heat exchanger is connected to the evaporator, and the evaporator is connected to the variable capacity compressor thereby forming a closed system in which refrigerant travels. 4. The refrigeration system of claim 3, where the compressor system further comprises: a drier positioned between the condenser and the evaporator and connected to the condenser and evaporator; and, a hot-gas bypass valve connected to the drier and the evaporator, where the hot-gas bypass valve and heat exchanger are connected in parallel to the drier and evaporator. 5. The refrigeration system of claim 1 where the heat transfer substance is insulation. 6. The refrigeration system of claim 5 where the insulation is closed cell urethane. 7. The refrigeration system of claim 7 where the closed cell urethane is Armaflex. 8. The refrigeration system of claim 7 where about ½ inch to 1 inch of Armaflex is engaged to the metal sheet of the heat transfer substance. 9. A compressor system comprising a closed system having an evaporator functionally engaged to a variable capacity compressor, where the compressor system selectably operates in at least a refrigeration mode and a hot-gas defrost mode and the evaporator is defrosted by circulation of gas therethrough. 10. The compressor system of claim 9 comprising: a variable capacity compressor; a condenser; a drier; a hot-gas bypass valve; a heat exchanger; and, an evaporator, where the variable capacity compressor is connected to the condenser, the condenser is connected to a drier, the drier is connected to a hot-gas bypass valve and heat exchanger in parallel, the hot-gas bypass valve and heat exchanger are connected to the evaporator, and the evaporator is connected to the variable capacity compressor thereby forming a closed system in which refrigerant travels. 11. The compressor system of claim 10 further comprising a controller functionally engaged to the hot-gas bypass valve where the controller selectably opens and closes the hot-gas bypass valve. 12. A temperature divider comprising: a wall; a partition spaced a distance from the wall, the partition having at least one metal sheet with a heat transfer substance attached thereto; and, a heat exchange chamber defined by the wall and partition. 13. The temperature divider of claim 12 further comprising a damper positioned in the partition. 14. The temperature divider of claim 12 further comprising a vent positioned in the wall. 15. The temperature divider of claim 12 where the heat transfer substance is insulation. 16. The temperature divider of claim 12 where the insulation is closed cell urethane. 17. The temperature divider of claim 12 where the closed cell urethane is Armaflex. 18. The temperature divider of claim 12 further comprising a fan positioned in the wall. 19. A multi temperature zone refrigeration system comprising: a cabinet with at least two different temperature cooling zones; a single compressor system engaged to the cabinet for cooling the at least two temperature cooling zones; and, a temperature divider positioned between and separating the at least two different temperature cooling zones, the temperature divider having a wall, a partition spaced a distance from the wall, the partition having at least one metal sheet with a heat transfer substance attached thereto, and a heat exchange chamber defined by the wall and partition. 20. The multi temperature zone refrigeration system of claim 19 where the heat transfer substance is closed cell urethane. 21. The multi temperature zone refrigeration system of claim 19 further comprising a fan positioned in the wall. 22. The multi temperature zone refrigeration system of claim 19 further comprising a damper positioned in the partition and a vent positioned in the wall to allow air to circulate there through. 23. The multi temperature zone refrigeration system of claim 19 where the compressor system comprises: a variable capacity compressor; a condenser; a drier; a hot-gas bypass valve; a heat exchanger; and, an evaporator, where the variable capacity compressor is connected to the condenser, the condenser is connected to the drier, the drier is connected to the hot-gas bypass valve and the heat exchanger in parallel, the hot-gas bypass valve and heat exchanger are connected to the evaporator, and the evaporator is connected to the variable capacity compressor thereby forming a closed system in which refrigerant travels. 24. The multi temperature zone refrigeration system of claim 23 where the compressor system further comprises a controller functionally engaged to the hot-gas bypass valve where the controller selectably opens and closes the hot-gas bypass valve. 25. The multi temperature zone refrigeration system of claim 19 where the cabinet has three different temperature cooling zones and one temperature zone is a freezer maintained between about −5° F. and 5° F., one temperature zone is a refrigerator maintained between about 34° F. and 38° F., and one temperature zone is a chiller maintained between about 45° F. and 65° F. 26. The multi temperature zone refrigeration system of claim 19 where the heat transfer substance is between about ½ inch and 1 inch thick. 27. A multi temperature zone refrigeration system comprising: a cabinet with at least two different temperature cooling zones; a cooling system engaged to the cabinet; and, a temperature divider positioned between and separating the at least two different temperature cooling zones, the temperature divider having a wall, a partition spaced a distance from the wall, the partition having at least one metal sheet with a heat transfer substance of closed cell urethane attached thereto, and a heat exchange chamber defined by the wall and partition. 28. The multi temperature zone refrigeration system of claim 27 where the cooling system is a compressor system comprising a closed system having an evaporator functionally engages to a variable capacity compressor, where compressor system selectably operates in at least a refrigeration mode and a hot-gas defrost mode an the evaporator is defrosted by circulated gas there through. 29. The multi temperature zone refrigeration system of claim 27 where the compressor system comprises: a variable capacity compressor; a condenser; a drier; a hot-gas bypass valve; a heat exchanger; an evaporator; where the variable capacity compressor is connected to the condenser, the condenser is connected to the drier, the drier is connected to the hot-gas bypass valve and the heat exchanger in parallel, the hot-gas by-pass valve and heat exchanger are connected to the evaporator, and the evaporator is connected to the variable capacity compressor thereby forming a closed system in which refrigerant travels; and, a controller functionally engaged to the hot-gas by-pass valve where the controller selectably opens and closes the hot-gas bypass valve. 30. A method of defrosting a variable capacity compressor cooling system with gas comprising the steps of: having a controller signal a hot-gas bypass valve to selectably open; having a variable capacity compressor compress relatively low pressure gas into a relatively high pressure gas; circulating the high pressure gas from the variable capacity compressor into a condenser, then into a drier, through the open hot-gas bypass valve, and into an evaporator; melting accumulated frost on the evaporator and thereby reducing the pressure of the gas; and, returning the relatively low pressure gas to the variable capacity compressor. | BACKGROUND OF THE INVENTION This invention relates generally to a refrigeration system and components thereof, and in particular, to a system having different temperature zones for cooling various food and beverage articles. People have used refrigerated devices to cool and freeze food and beverage articles for many years. Traditionally, these devices utilize a compressor functionally connected to an insulated container. The compressor and associated components and piping change the pressure of refrigerant to absorb heat from the insulated container. A fan system circulates air into and inside the insulated container. A temperature control device is typically connected to the compressor. The temperature control device cycles the compressor on and off as needed to maintain a desired temperature in the insulated container. Cycling a compressor on and off requires a significant amount of energy and results in rather loud noises. Variable capacity compressors have been created to provide a compressor that is continuously operating. The speeds of the compressor can be varied substantially and continuously over a wide range of predefined speeds. Such compressors are disclosed in U.S. Pat. Nos. RE 33,620 to Persem and 4,765,150 to Persem. Operation of variable capacity compressors, like all compressors, results in frost building up on the heat exchange elements. The compressors must be routinely defrosted so that the compressor may operate optimally. One method of defrosting involves running hot gas either through or near the heat exchange elements. Such defrost mechanisms are disclosed in U.S. Pat. Nos. 4,979,371 to Larson; 3,234,754 to Quick; 3,234,753 to Quick; 3,234,748 to Quick; and 3,645,109 to Quick. None of these mechanisms have been designed or utilized with variable capacity compressors. Further, all these mechanisms utilize extensive networks of tubing and control valves to accomplish defrosting. Many refrigeration devices also have different temperature zones. For example, the common home refrigerator has a freezer section and a refrigeration section. Creating different temperatures in different sections of a refrigeration device can be accomplished in at least two methods. One method involves using a different compressor for each section. Another method involves using fans or the like to circulate cold air from a colder section to a warmer section. The operation of the fans may be controlled by a temperature control device. For example, U.S. Pat. No. 4,505,126 to Jones et al. discloses a food product transport system, wherein motorized fans are used to circulate air from one section to another. The fans are positioned in partitions separating the different sections. U.S. Pat. No. 6,000,232 to Witten-Hannah et al. discloses a refrigeration system having a freezer section and a refrigeration section in parallel alignment. This patent further discloses a method wherein motorized fans are used to control the amount of chilled air entering each section. U.S. Pat. No. 5,081,850 to Wakatsuki et al. discloses a refrigerator that has two sections separated by a partition, wherein cool air is circulated throughout the sections and through the partition. All of these devices require the circulation of air from one section to another to create different temperatures in each section. Accordingly, a need exists for an improved refrigeration system and components thereof that solves these and other deficiencies in the prior art. Of course, the present invention may be used in a multitude of situations where similar performance capabilities are required. SUMMARY OF THE INVENTION The present invention provides a refrigeration system that is cost-effective to manufacture, efficient to operate, relatively quiet when functioning, and overcomes certain of the deficiencies in the prior art. The invention provides for a refrigeration system and components thereof. In one embodiment, the refrigeration system has a container with at least two different temperature cooling zones, which are separated by a divider. The divider has a wall and a partition spaced apart from each other. The partition has a heat transfer plate, which has a sheet with a heat transfer substance attached thereto. In one embodiment, the refrigeration system is cooled by a compressor system having refrigeration and hot-gas defrost modes. A controller controls and selectably operates the compressor system. Preferably, the compressor system has a variable capacity compressor. The present invention also provides for a compressor system, which is a closed system, wherein an evaporator is functionally connected to a variable capacity compressor. The compressor system selectably operates in at least a refrigeration mode and a hot-gas defrost mode. During the hot-gas defrost mode, the evaporator is defrosted by circulation of gas therethrough. In one embodiment, the compressor system has a variable capacity compressor connected to a condenser, which is further connected to a drier, which in turn is connected to a hot-gas by-pass valve and a heat exchanger. The hot-gas by-pass valve and heat exchanger are connected in parallel to one another and are both connected to an evaporator. The evaporator is connected to the variable capacity compressor to form the closed system. A controller may selectably open and close the hot gas bypass valve. While one possible application of the present invention is in connection with residential and commercial refrigeration of food and beverage articles, many other applications are possible and references to use in connection with residential and commercial situations should not be deemed to limit the uses of the present invention. The terms “heat exchanger,” “evaporator,” “condenser,” “capillary tube,” “fan,” “cabinet,” “door,” “damper,” “compressor,” “by-pass valve,” and “heat transfer panel” as used herein should not be interpreted as being limited to specific forms, shapes, numbers, or compositions of a heat exchanger, evaporator, condenser, capillary tube, fan, cabinet, door, damper, compressor, by-pass valve, and heat transfer panel. Rather, the evaporator, condenser, capillary tube, fan, cabinet, door, damper, compressor, by-pass valve, and heat transfer panel may have a wide variety of shapes and forms, may be provided in a wide variety of numbers, and may be composed of a wide variety of materials. These and other objects and advantages of the present invention will become apparent from the detailed description, claims, and accompanying drawings. DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross sectional view of a refrigeration system in accordance with one embodiment of the present invention; FIG. 2 is a schematic view of the refrigeration system of FIG. 1; FIG. 3 is a schematic view of a portion of the refrigeration system of FIG. 1; FIG. 4 is a schematic view of a portion of the refrigeration system of FIG. 1; FIG. 5 is a perspective view of a refrigeration system in accordance with one embodiment of the present invention; FIG. 6 is a partial cross sectional view of the refrigeration system of FIG. 5; FIG. 7 is a perspective view of a refrigeration system of FIG. 5; FIG. 8 is a perspective view of a refrigeration system in accordance with one embodiment of the present invention; FIG. 9 is a perspective view of a refrigeration system in accordance with one embodiment of the present invention; FIG. 10 is a partial cross sectional view of a refrigeration system in accordance with one embodiment of the present invention; FIG. 11 is a front view of a refrigeration system in accordance with one embodiment of the present invention; and, FIG. 12 is a perspective view of a refrigeration system in accordance with one embodiment of the present invention, shown with a portion of the system removed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Illustrative embodiments of a refrigeration system (identified generally as 30) in accordance with the present invention are shown in FIGS. 1 through 12. While the invention may be susceptible to embodiment in different forms, there are shown in the drawings, and herein are described in detail, certain illustrative embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to those as illustrated and described herein. Additionally, features illustrated and described with respect to one embodiment could be used in connection with other embodiments. The present invention provides a refrigeration system 30 to cool at least one cooling compartment or cooling zone 35. A cooling system, preferably a compressor system 32, is functionally connected to the cooling zone 35 and effectively cools the cooling zone 35. In a preferred embodiment, a portion of the compressor system 32, specifically an evaporator 66, is positioned inside a cooling zone 35. A fan 68 circulates air inside the cooling zone 35 and past the evaporator 66, thus cooling the air. The refrigeration system 30 may have more than one cooling zone 35. Multiple cooling zones 35 may be separated by at least one heat transfer panel 20. In one embodiment, shown in FIGS. 1-4, the cooling system is a compressor system 32. The compressor system 32 has a series of components functionally engaged to one another to form a closed system. Refrigerant, variously in the form of liquid or gas, is circulated in the compressor system 32. The compressor system 32 has a compressor 52, which is preferably a variable capacity compressor. Examples of such variable capacity compressors include those disclosed in U.S. Pat. Nos. RE 33,620 to Persem and 4,765,150 to Persem, which are hereby incorporated in their entireties for all purposes. Variable capacity compressors found effective in the present invention include without limitation those manufactured and sold by Embraco of Joinville, S.C., Brazil (sales through Embraco North America of Duluth, Ga.) such as model VEGY 7H or VEGY 8H. The compressor 52 is connected to a condenser 54. Condensers found effective in the present invention include without limitation those manufactured and sold by Outokumpu Heatcraft USA, LLC. of Grenada, Miss. A condenser fan 56, such as model 9906L manufactured and sold by EBM Industries, Inc. of Farmington, Conn., may be provided in relation to the condenser 54 to circulate air around the condenser 54. The condenser 54 is connected to a drier 58. Driers found effective in the present invention include without limitation those manufactured and sold by Parker-Hannifm Corp., Climate Systems Division, of Greenfield, Tenn. In one embodiment, a dual inlet drier is utilized by oriented such that the direr has one inlet and two outlets. The drier 58 is connected in parallel to a hot gas by-pass valve 60 and a capillary tube 62. By-pass valves found effective in the present invention include without limitation those manufactured and sold by Parker-Hannifin Corp., Fluid Control Division, of New Britain, Conn., preferably model number 04E20C1-ZO1ABBOSO5. While these components may be housed in any portion of the cabinet 34 of the refrigeration system 30, it is preferable that these components are not positioned inside the cooling zones 35. As shown in FIGS. 2-4, the tubing leading from the capillary tube 62 is connected to a heat exchanger 64. In the embodiment shown, the heat exchanger 64 is essentially a section of coiled tubing. Heat exchangers found effective in the present invention include without limitation those manufactured and sold by Perlick Corp. of Milwaukee, Wis. The tubing leading from the hot gas by-pass valve 60 and heat exchanger 64 join together and are connected to an evaporator 66. The evaporator 66 is preferably positioned in the cooling zone 35. A fan 68, such as those manufactured and sold by EBM Industries, Inc., may be provided to circulate the air inside the cooling zone 35 past the evaporator 66. Evaporators found effective in the present invention include those manufactured and sold by Outokumpu Heatcraft USA, LLC. The evaporator 66 is connected to the compressor 52 via tubing, thereby forming a closed system in which the refrigerant travels. The tubing passes through the heat exchanger 64. A controller 70 is provided to control operation of the compressor system 32. Controllers found effective in the present invention include without limitation those manufactured by Dixell srl of Italy and distributed by Weiss Instruments, Inc. of Holtsville, N.Y. as model number XW60L. The compressor system 32 operates in at least three modes: refrigeration, hot-gas defrost, and drip. The controller 70 determines the mode of operation of the compressor system 32 based on preset values such as temperature or time. The compressor system 32 operates in refrigeration mode until a preset termination value, such as temperature or time, is met. When such value is met, the controller 70 switches the compressor system 32 to operate in hot-gas defrost mode until a certain preset value, such as temperature or time, is met. Upon meeting this preset value, the compressor system 32 enters the drip mode. The drip mode allows moisture to drip from the evaporator 66 for a predetermined time. When drip mode is completed, the compressor system 32 may enter a recovery period or return to the refrigeration mode. When operating in refrigeration mode, the compressor system 32 cools the cooling zone(s) 35. In this mode, the compressor system 32 continuously circulates, evaporates, and condenses a fixed supply of refrigerant in a closed system. As shown in FIG. 4, refrigerant travels in direction C from the compressor 52 into the condenser 54 through the drier 58 into the heat exchanger 64 through the evaporator 66 and back to the compressor 52. The refrigerant is in a low pressure gaseous form when it enters the compressor 52. The compressor 52, either during the compression cycle of a variable capacity compressor or while the compressor is operating as a single speed compressor, increases the pressure of the gas refrigerant and discharges high pressure gas into the condenser 54. In the condenser 54, heat is removed from the high pressure gas resulting in the refrigerant condensing into a liquid, still under high pressure. From the condenser 54, the high pressure liquid refrigerant is fed into the drier 58. During the refrigeration mode, by-pass valve 60 is de-energized or closed. Therefore, the high pressure liquid refrigerant is pushed through the drier 58 and into the capillary tube 62. Refrigerant travels through the capillary tube 62, which is part of the heat exchanger 64. The heat exchanger 64, and in one embodiment the capillary tube 62 decreases the pressure of the refrigerant. The refrigerant is a low pressure liquid as it enters the evaporator 66. The refrigerant absorbs heat from the cooling zone 35, and evaporates and expands into a low pressure gas as it travels through the evaporator 66. Refrigerant returns to the compressor 52 in low pressure gaseous form. This concludes one cycle of the refrigeration mode. During the refrigeration mode, ice or frost may accumulate on the evaporator 66 of the compressor system 32. This accumulation results in decreased performance and efficiency. In the embodiment of the present invention shown in FIGS. 2-4, the compressor system 32 has the ability to melt this accumulation or defrost the compressor system 32. According to the invention, this defrost is accomplished through the use of hot gas. Such hot gas defrost mechanisms are disclosed in U.S. Pat. Nos. 4,979381 to Larson; 3,234,754 to Quick; 3,234,753 to Quick; 3,234,748 to Quick; and 3,645,109 to Quick, all of which are incorporated herein in their entireties for all purposes. One embodiment of the hot gas defrost mechanism according to the invention is shown in FIG. 3. In this embodiment, when the compressor system 32 operates in hot-gas defrost mode, a fixed supply of medium to high pressure gaseous refrigerant is continuously circulated in the closed system. The by-pass valve 60 is opened thereby allowing the refrigerant to by pass the heat exchanger 64 and thus travel at a higher velocity in the system. Specifically, refrigerant travels in direction G from the compressor 52 through the condenser 54 and into the drier 58. Recall that, in refrigeration mode, the refrigerant is in a low pressure gaseous form when it enters the compressor 52 and is in a high pressure gaseous form when it leaves the compressor 52 to enter the condenser 54, where it is condensed into a high pressure liquid. To the contrary during the hot-gas defrost mode, the condenser 54 does not change the high pressure gas refrigerant into a liquid. The condenser 54 does not change the high pressure gas refrigerant into a liquid because of the relatively high velocity of the gas as it travels through the condenser 54 and the temperature-pressure relationship of the gas relative to the surrounding ambient temperature. The temperature-pressure relationship is such that little to no cooling of the refrigerant occurs. The gaseous refrigerant is permitted to flow into the drier 58 and then, because the by-pass valve 60 is energized or open, the gaseous refrigerant bypasses the heat exchanger 64 and travels directly to the evaporator 66. The heat from the gaseous refrigerant is transferred to the frost accumulated on the evaporator 66. This heat transfer results in the frost melting and the temperature, and thus the pressure, of the gaseous refrigerant decreasing. The gaseous refrigerant then returns to the compressor 52. This concludes one cycle of the hot-gas defrost mode. As discussed above and shown in FIGS. 1, 2, 5, 6, 7, and 9, according to one aspect of the invention, the refrigeration system 30 may have more than one cooling zone 35. The cooling zones 35 are separated by a divider 43. The divider 43 may be permanently, removably, or selectably positioned in the refrigeration system 30. In one embodiment, the divider 43 is bracketed in the refrigeration system 30. In the embodiment shown in FIGS. 1 and 10, the divider 43 has a wall. 39 and a partition 36, arranged in generally parallel relation to each other and spaced slightly apart. As shown in FIG. 10, the spacing between wall 39 and partition 36 is a distance E, and the wall and the partition define a heat exchange chamber 37 therebetween. The wall 39 may have a vent or plurality of vents 41 through which air may circulate. A fan or multiple fans 40 may be positioned in communication with the divider 43, such as in an opening provided for the purpose in the wall 39, or otherwise in the cooling zone 35, to facilitate air circulation. Fans found effective in the present invention include without limitation those manufactured and sold by EBM Industries, Inc. For example, as shown in FIGS. 1 and 10, fans 40 may be used to circulate air in a direction A inside the cooling zones 35. The divider 43 transfers heat from one cooling zone 35 to another. To accomplish this transfer, the partition 36 has a heat transfer panel 20. Any number and configuration of heat transfer panels 20 may be used, depending on the desired performance of the refrigeration system 30. In the embodiment shown in FIG. 10, the heat transfer panel 20 has at least one metal sheet 48, which is preferably a sheet of stainless steel. A heat transfer substance 50 is connected in heat transfer relation to the metal sheet 48. The heat transfer substance 50 may also be engaged to the wall 39 or any other section of the cooling zones 35 of refrigeration system 30. The heat transfer substance 50 may be engaged to metal sheet 48 by any method and is preferably attached to the metal sheet by adhesive. The heat transfer substance 50 may be formed of any type of composition, but is preferably formed of closed cell urethane insulation and most preferably of material sold under the commercial name Armaflex. Both the metal sheet 48 and heat transfer substance 50 may be of varying thicknesses D and T respectively depending on a number of characteristics such as the desired heat transfer from one cooling zone 35 to another cooling zone 35 and the number and temperatures of the cooling zones 35. In the embodiments shown in FIGS. 1 and 7, a damper 38 is placed in the divider 43. The damper 38 is preferably integrated into the partition 36. The damper 38 allows air to circulate between different cooling zones 35. Depending on the configuration of the damper 38, air may be allowed to circulate from a colder zone 42 such as a freezer to a warmer zone 44 such as a refrigerator or vice versa. Preferably, the damper 38 selectably controls the circulation of air between the cooling zones 35. The damper 38 may have or be functionally connected to a temperature sensitive control. The control monitors the temperature in a given cooling zone 35. The control signals the damper 38 to circulate air between the cooling zones 35 to achieve a desired temperature. For example, in one embodiment, the damper 38 allows cold air to pass from a colder zone 42 to a warmer zone 44. The damper 38 may be a selectably positionable door or partition, a vent system, a fan, or the like. Dampers found effective in the present invention include without limitation those manufactured and sold by Invensys Appliance Controls of Carol Stream, Ill. as model SK-9019. Such a damper has a panel that pivots between a fully closed position and a position that is open about 90° relative to the fully closed position, thereby regulating the amount of air that passes through the damper. The refrigeration system 30 and components thereof of the present invention may be used in a variety of applications. One such application is residential, commercial, and industrial food and beverage cooling. Specifically, the refrigeration system 30 and components thereof of the present invention may be used in refrigeration cabinets 34. As shown in FIGS. 5, 8, and 9, the refrigeration cabinets 34 may have a single cooling zone 35 or multiple cooling zones 35 separated by dividers 43. For example, a refrigeration cabinet 34 with multiple cooling zones 35 may have two zones 35 where one zone is a freezer 42 and the other zone is a refrigerator 44. Alternatively, the refrigeration cabinet 34 may have a freezer 42 and a chiller 46. Further, the refrigeration cabinet 34 may have a refrigerator 44 and a chilling zone 46. In the embodiment shown in FIGS. 1, 2, and 9, the refrigeration cabinet 34 has freezer 42, refrigerator 44, and a chiller 46. The number and relative temperature of the cooling zones 35 may be varied in any number of configurations. The cabinet 34, and the cooling zones 35 contained therein, may be any shape or size. In one embodiment, the cabinet 34 is designed to fit below a counter or sink. In another embodiment, the cabinet 34 is designed to also finction as a bar. The cabinet 34 may be designed to have any finish such as stainless steel, wood, or other finish and to fit into any decor, such as contemporary or traditional. The cabinet 34 may also have any number of doors 33 for accessing a single cooling zone 35 or multiple cooling zones 35. For example as shown in FIG. 9, the cabinet 34 may have three cooling zones 35 with each zone 35 having a single door 33. Each zone 35 may also have multiple doors 33. The doors 33 may be any material or combination thereof. For example as shown in FIG. 9, the doors 33 may be partially or entirely made of glass, metal, wood, or the like. As shown in FIGS. 11 and 12, shelving 72, racks 74, and the like may be permanently or selectably positioned inside the cooling zones 35. In addition, a single temperature readout 90, or a plurality thereof, may be provided. A readout 90 may be associated with each cooling zone 35. The readouts 90 allow for easy determination of the temperature of a cooling zone 35. EXAMPLES The following examples illustrate different performance and physical characteristics of different refrigeration cabinets 34 employing the refrigeration system 30 and components thereof in accordance with the present invention. The refrigeration systems 30 discussed below each have at least two, and sometimes three, cooling zones 35. The cooling zones are separated by at least one divider 43 that has at least one heat exchange panel 20. The heat exchange panels 20 in each example utilize different thicknesses T of the heat transfer substance 50. The tables associated with each example show the performance of specific cabinets 34 in three separate air temperatures outside of the cooling zone 35 (ambient temperature conditions): 70° F., 90° F., and 110° F. Performance is measured as the BTUs/hour required to maintain the desired temperature inside the cooling zones 35. To arrive at this measurement, three values are multiplied together. These values are Delta T, K-Factor, and the material area of the cooling zone 35 in square feet. Delta T is the temperature difference between the ambient temperature conditions and the temperature inside the cooling zone 35. Delta T is measured in degrees Fahrenheit. K-Factor is the measurement used to quantify the resistance to heat transfer of a component of the cabinet 34. K-Factor is measured in BTU/inch/hour/square foot/degree F. Example 1 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. In this example, the refrigeration cabinet 34 measures 48 inches by 24 inches by 34 inches. One cooling zone 35 is a freezer 42 maintained between −5° F. and 5° F. The freezer compartment 42 measures 20.5 inches by 20.5 inches by 27 inches. The other cooling zone 35 is a refrigerator 44 maintained between 34° F. and 38° F. The refrigerator compartment measures 20.5 inches by 20.5 inches by 27 inches. The freezer 42 and refrigerator 44 each have a single separate door 33 for access thereto. The freezer 42 and refrigerator 44 are separated by a divider 43 measuring 3 inches thick by 20.5 inches by 27 inches. The divider 43 has a partition 36 with heat transfer panel 20 having a ¾ inch thick heat transfer substance 50. The heat transfer substance 50 is Armaflex. TABLE 1 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 186 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 304 REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 4.00 2 42 0.13 11 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet −8 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 36 BTU/HR TOTAL CABINET LOAD 340 (BTU/HR) TABLE 2 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 217 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 350 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 4.00 2 62 0.13 16 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 23 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 77 BTU/HR TOTAL CABINET LOAD 428 (BTU/HR) TABLE 3 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 249 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 397 REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 4.00 2 82 0.13 21 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 54 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 118 BTU/HR TOTAL CABINET LOAD 515 (BTU/HR) Example 2 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 1, except that the heat transfer substance 50 is ½ inch thick Armaflex. TABLE 4 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 215 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 333 REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 4.00 2 42 0.13 11 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet −37 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 7 BTU/HR TOTAL CABINET LOAD 340 (BTU/HR) TABLE 5 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 247 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 380 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 4.00 2 62 0.13 16 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet −6 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS * (BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 48 BTU/HR TOTAL CABINET LOAD 428 (BTU/HR) TABLE 6 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 278 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 426 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 4.00 2 82 0.13 21 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 24 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 88 BTU/HR TOTAL CABINET LOAD 515 (BTU/HR) Example 3 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 1, except that the heat transfer substance 50 is one inch thick Armaflex. TABLE 7 70° F. ambient temperature MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 171 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 289 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 4.00 2 42 0.13 11 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 7 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 51 BTU/HR TOTAL CABINET LOAD 340 (BTU/HR) TABLE 8 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 202 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 335 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 4.00 2 62 0.13 16 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 38 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 92 BTU/HR TOTAL CABINET LOAD 428 (BTU/HR) TABLE 9 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 MODEL (Outside Wall Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 234 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load 382 BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 4.00 2 82 0.13 21 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 69 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 133 BTU/HR TOTAL CABINET LOAD 515 (BTU/HR) Example 4 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 1, except that this refrigeration cabinet has a refrigerator 44 and a chiller 46 instead of a freezer 43 and a refrigerator 44. The chiller 46 is maintained at about 45° F. TABLE 10 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.75 7 0.27 10 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 66 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 110 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet 32 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load 71 BTU/HR TOTAL CABINET LOAD 181 (BTU/HR) TABLE 11 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 0.75 7 0.27 10 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 98 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 231 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 62 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 116 TOTAL CABINET LOAD 347 (BTU/HR) TABLE 12 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 0.75 7 0.27 10 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 130 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 278 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 65 0.13 21 Height)/144 Back (Length × Height)/144 4.25 2 65 0.13 18 Side Rt (Depth × Height)/144 5.08 2 65 0.13 21 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 4.00 2 75 0.13 20 Top (Length × Depth)/144 4.00 1.5 65 0.13 23 Total Heat Leak Into Cabinet 93 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 157 TOTAL CABINET LOAD 435 (BTU/HR) Example 5 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 is essentially the same cabinet of Example 4, except that the heat transfer substance 50 is ½ inch thick Armaflex. TABLE 13 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.5 7 0.27 15 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 71 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 115 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet 27 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 66 TOTAL CABINET LOAD 181 (BTU/HR) TABLE 14 90° F. ambient temperature MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 0.5 7 0.27 15 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 103 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 236 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 58 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 112 TOTAL CABINET LOAD 347 (BTU/HR) TABLE 15 110° F. ambient temperature MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 0.5 7 0.27 15 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 134 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 282 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 65 0.13 21 Height)/144 Back (Length × Height)/144 4.25 2 65 0.13 18 Side Rt (Depth × Height)/144 4.79 2 65 0.13 20 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 4.81 2 75 0.13 23 Top (Length × Depth)/144 4.00 1.5 65 0.13 23 Total Heat Leak Into Cabinet 91 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 155 TOTAL CABINET LOAD 438 (BTU/HR) Example 6 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 is the same cabinet of Example 4, except that the heat transfer substance 50 is 1 inch thick Armaflex. TABLE 16 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 1 7 0.27 7 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 64 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 108 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet 34 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 73 TOTAL CABINET LOAD 181 (BTU/HR) TABLE 17 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 1 7 0.27 7 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 96 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 229 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 65 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 119 TOTAL CABINET LOAD 347 (BTU/HR) TABLE 18 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 1 7 0.27 7 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 127 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 275 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 65 0.13 21 Height)/144 Back (Length × Height)/144 4.25 2 65 0.13 18 Side Rt (Depth × Height)/144 5.08 2 65 0.13 21 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 4.00 2 75 0.13 20 Top (Length × Depth)/144 4.00 1.5 65 0.13 23 Total Heat Leak Into Cabinet 96 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 160 TOTAL CABINET LOAD 435 (BTU/HR) Example 7 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 is the same cabinet as Example 4, except that the chiller 46 is maintained at about 65° F. TABLE 19 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.75 27 0.27 37 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 94 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 138 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 5 0.13 2 Height)/144 Back (Length × Height)/144 4.25 2 5 0.13 1 Side Rt (Depth × Height)/144 5.08 2 5 0.13 2 Side Lt (Depth × Height)/144 3.84 0.75 −27 0.27 −37 Bottom (Depth × Length)/144 4.00 2 15 0.13 4 Top (Length × Depth)/144 4.00 1.5 5 0.13 2 Total Heat Leak Into Cabinet −27 ALLOWANCE FOR DOOR 10 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 2 TOTAL CABINET LOAD 140 (BTU/HR) TABLE 20 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 0.75 27 0.27 37 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 126 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 180 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.75 −27 0.27 −37 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet 4 ALLOWANCE FOR DOOR 15 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 38 TOTAL CABINET LOAD 217 (BTU/HR) TABLE 21 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 0.75 27 0.27 37 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 157 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 221 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.75 −27 0.27 −37 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 35 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 74 TOTAL CABINET LOAD 295 (BTU/HR) Example 8 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 is essentially the same cabinet of Example 7, except that the heat transfer substance 50 is ½ inch thick Armaflex. TABLE 22 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.5 27 0.27 56 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 113 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 157 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 5 0.13 2 Height)/144 Back (Length × Height)/144 4.25 2 5 0.13 1 Side Rt (Depth × Height)/144 5.08 2 5 0.13 2 Side Lt (Depth × Height)/144 3.84 0.5 −27 0.27 −56 Bottom (Depth × Length)/144 4.00 2 15 0.13 4 Top (Length × Depth)/144 4.00 1.5 5 0.13 2 Total Heat Leak Into Cabinet −46 ALLOWANCE FOR DOOR 10 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR −17 TOTAL CABINET LOAD 140 (BTU/HR) TABLE 23 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 0.5 27 0.27 56 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 144 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 198 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.5 −27 0.27 −56 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet −15 ALLOWANCE FOR DOOR 15 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 19 TOTAL CABINET LOAD 217 (BTU/HR) TABLE 24 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 0.5 27 0.27 56 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 176 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 240 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.5 −27 0.27 −56 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 16 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 55 TOTAL CABINET LOAD 295 (BTU/HR) Example 9 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 is essentially the same cabinet of Example 7, except that the heat transfer substance 50 is one inch thick Armaflex. TABLE 25 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 32 0.13 11 Height)/144 Back (Length × Height)/144 4.25 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 1 27 0.27 28 Side Lt (Depth × Height)/144 4.79 2 32 0.13 10 Bottom (Depth × Length)/144 4.81 2 52 0.13 16 Top (Length × Depth)/144 4.00 1.5 32 0.13 11 Total Heat Leak Into Cabinet 85 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 129 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 5 0.13 2 Height)/144 Back (Length × Height)/144 4.25 2 5 0.13 1 Side Rt (Depth × Height)/144 5.08 2 5 0.13 2 Side Lt (Depth × Height)/144 3.84 1 −27 0.27 −28 Bottom (Depth × Length)/144 4.00 2 15 0.13 4 Top (Length × Depth)/144 4.00 1.5 5 0.13 2 Total Heat Leak Into Cabinet −18 ALLOWANCE FOR DOOR 10 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 11 TOTAL CABINET LOAD 140 (BTU/HR) TABLE 26 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 52 0.13 17 Height)/144 Back (Length × Height)/144 4.25 2 52 0.13 14 Side Rt (Depth × Height)/144 3.84 1 27 0.27 28 Side Lt (Depth × Height)/144 4.79 2 52 0.13 16 Bottom (Depth × Length)/144 4.81 2 72 0.13 23 Top (Length × Depth)/144 4.00 1.5 52 0.13 18 Total Heat Leak Into Cabinet 116 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 170 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 25 0.13 8 Height)/144 Back (Length × Height)/144 4.25 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 1 −27 0.27 −28 Bottom (Depth × Length)/144 4.00 2 35 0.13 9 Top (Length × Depth)/144 4.00 1.5 25 0.13 9 Total Heat Leak Into Cabinet 13 ALLOWANCE FOR DOOR 15 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 47 TOTAL CABINET LOAD 217 (BTU/HR) TABLE 27 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR REFRIGERATOR SIDE Front (Door)(Length × 5.08 2 72 0.13 24 Height)/144 Back (Length × Height)/144 4.25 2 72 0.13 20 Side Rt (Depth × Height)/144 3.84 1 27 0.27 28 Side Lt (Depth × Height)/144 4.79 2 72 0.13 22 Bottom (Depth × Length)/144 4.81 2 92 0.13 29 Top (Length × Depth)/144 4.00 1.5 72 0.13 25 Total Heat Leak Into Cabinet 148 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 212 BTU/HR CHILLER SIDE Front (Door)(Length × 5.08 2 45 0.13 15 Height)/144 Back (Length × Height)/144 4.25 2 45 0.13 12 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 1 −27 0.27 −28 Bottom (Depth × Length)/144 4.00 2 55 0.13 14 Top (Length × Depth)/144 4.00 1.5 45 0.13 16 Total Heat Leak Into Cabinet 44 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 83 TOTAL CABINET LOAD 295 (BTU/HR) Example 10 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. The refrigeration cabinet 34 measures 72 inches by 24 inches by 34 inches. One cooling zone 35 is a freezer 42 maintained between −5° F. and 5° F. The freezer 42 measures 20.5 inches by 20.5 inches by 27 inches. The other cooling zone 35 is a refrigerator 44 maintained between 34° F. and 38° F. The refrigerator 44 measures 47.5 inches by 20.5 inches by 27 inches The freezer 42 has a single door 33 and the refrigerator 44 has two doors 33 for access thereto. The freezer 42 and refrigerator 44 are separated by a divider 43 measuring 3 inches by 20.5 inches by 27 inches. The divider 43 has a partition 36 with ¾ inch thick heat transfer substance 50. The heat transfer substance 50 is Armaflex. TABLE 28 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 186 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 304 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 32 0.13 21 Height)/144 Back (Length × Height)/144 10.17 2 32 0.13 21 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 8.00 2 42 0.13 22 Top (Length × Depth)/144 8.00 1.5 32 0.13 22 Total Heat Leak Into Cabinet 37 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 106 TOTAL CABINET LOAD 410 (BTU/HR) TABLE 29 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 217 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 350 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 52 0.13 34 Height)/144 Back (Length × Height)/144 10.17 2 52 0.13 34 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 8.00 2 62 0.13 32 Top (Length × Depth)/144 8.00 1.5 52 0.13 36 Total Heat Leak Into Cabinet 95 ALLOWANCE FOR DOOR 70 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 184 TOTAL CABINET LOAD 534 (BTU/HR) TABLE 30 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 249 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 397 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 72 0.13 48 Height)/144 Back (Length × Height)/144 10.17 2 72 0.13 48 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 8.00 2 82 0.13 43 Top (Length × Depth)/144 8.00 1.5 72 0.13 50 Total Heat Leak Into Cabinet 152 ALLOWANCE FOR DOOR 90 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 261 TOTAL CABINET LOAD 658 (BTU/HR) Example 11 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 and three doors 33 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 10, except that the heat transfer substance 50 is ½ inch thick Armaflex. TABLE 31 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 215 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 333 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 32 0.13 21 Height)/144 Back (Length × Height)/144 10.17 2 32 0.13 21 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 8.00 2 42 0.13 22 Top (Length × Depth)/144 8.00 1.5 32 0.13 22 Total Heat Leak Into Cabinet 8 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 77 TOTAL CABINET LOAD 410 (BTU/HR) TABLE 32 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 247 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 380 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 52 0.13 34 Height)/144 Back (Length × Height)/144 10.17 2 52 0.13 34 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 8.00 2 62 0.13 32 Top (Length × Depth)/144 8.00 1.5 52 0.13 36 Total Heat Leak Into Cabinet 65 ALLOWANCE FOR DOOR 70 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 154 TOTAL CABINET LOAD 534 (BTU/HR) TABLE 33 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 278 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR 30 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 426 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 72 0.13 48 Height)/144 Back (Length × Height)/144 10.17 2 72 0.13 48 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 8.00 2 82 0.13 43 Top (Length × Depth)/144 8.00 1.5 72 0.13 50 Total Heat Leak Into Cabinet 122 ALLOWANCE FOR DOOR 90 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR 0 HEATERS *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 231 BTU/HR TOTAL CABINET LOAD 658 (BTU/HR) Example 12 The following tables illustrate the performance of a refrigeration cabinet 34 with two cooling zones 35 and three doors 33 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 10, except that the heat transfer substance 50 is one inch thick Armaflex. TABLE 34 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 171 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 289 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 32 0.13 21 Height)/144 Back (Length × Height)/144 10.17 2 32 0.13 21 Side Rt (Depth × Height)/144 5.08 2 32 0.13 11 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 8.00 2 42 0.13 22 Top (Length × Depth)/144 8.00 1.5 32 0.13 22 Total Heat Leak Into Cabinet 52 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 121 TOTAL CABINET LOAD 410 (BTU/HR) TABLE 35 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 202 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 335 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 52 0.13 34 Height)/144 Back (Length × Height)/144 10.17 2 52 0.13 34 Side Rt (Depth × Height)/144 5.08 2 52 0.13 17 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 8.00 2 62 0.13 32 Top (Length × Depth)/144 8.00 1.5 52 0.13 36 Total Heat Leak Into Cabinet 110 ALLOWANCE FOR DOOR 70 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 199 TOTAL CABINET LOAD 534 (BTU/HR) TABLE 36 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 44″ 20.5 26.5 4.875″ × 8.625″ External 48″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 234 ALLOWANCE FOR DOOR 80 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 382 REFRIGERATOR SIDE Front (Door)(Length × 10.17 2 72 0.13 48 Height)/144 Back (Length × Height)/144 10.17 2 72 0.13 48 Side Rt (Depth × Height)/144 5.08 2 72 0.13 24 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 8.00 2 82 0.13 43 Top (Length × Depth)/144 8.00 1.5 72 0.13 50 Total Heat Leak Into Cabinet 167 ALLOWANCE FOR DOOR 90 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load BTU/HR 276 TOTAL CABINET LOAD 658 (BTU/HR) Example 13 The following tables illustrate the performance of a refrigeration cabinet 34 with three cooling zones 35 and three doors 33 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. The refrigeration cabinet 34 measures 72 inches by 24 inches by 34 inches. One cooling zone 35 is a freezer 42 maintained between −5° F. and 5° F. The freezer 42 measures 20.5 inches by 20.5 inches by 27 inches; The next cooling zone 35 is a refrigerator 44 maintained between 34° F. and 38° F. The refrigerator 44 measures 47.5 inches by 20.5 inches by 27 inches. The final cooling zone is a chiller 46 maintained between 45° F. and 65° F. The freezer 42, refrigerator 44, and chiller 46 each have a single door 33 for access thereto. The freezer 42 and refrigerator 44 and the refrigerator 44 and chiller 46 are separated by dividers 43. The dividers 43 measure 3 inches by 20.5 inches by 27 inches. The dividers 43 have a partition 36 with ¾ inch thick heat transfer substance 50. The heat transfer substance 50 is Armaflex. TABLE 37 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 186 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 304 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 32 0.13 9 Height)/144 Back (Length × Height)/144 4.45 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.75 7 0.13 5 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 3.50 2 42 0.13 10 Top (Length × Depth)/144 3.50 1.5 32 0.13 10 Total Heat Leak Into Cabinet −17 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 27 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 25 0.13 7 Height)/144 Back (Length × Height)/144 4.34 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 3.75 2 35 0.13 9 Top (Length × Depth)/144 3.75 1.5 25 0.13 8 Total Heat Leak Into Cabinet 29 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 68 TOTAL CABINET LOAD 399 (BTU/HR) TABLE 38 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 217 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 350 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 52 0.13 15 Height)/144 Back (Length × Height)/144 4.45 2 52 0.13 15 Side Rt (Depth × Height)/144 3.84 0.75 7 0.13 5 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 3.50 2 62 0.13 14 Top (Length × Depth)/144 3.50 1.5 52 0.13 16 Total Heat Leak Into Cabinet 5 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 59 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 45 0.13 13 Height)/144 Back (Length × Height)/144 4.34 2 45 0.13 13 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 3.75 2 55 0.13 13 Top (Length × Depth)/144 3.75 1.5 45 0.13 15 Total Heat Leak Into Cabinet 59 ALLOWANCE FOR DOOR 30 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 108 TOTAL CABINET LOAD 517 (BTU/HR) TABLE 39 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.75 43 0.27 60 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 249 ALLOWANCE FOR DOOR 75 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 392 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 72 0.13 21 Height)/144 Back (Length × Height)/144 4.45 2 72 0.13 21 Side Rt (Depth × Height)/144 3.84 0.75 7 0.13 5 Side Lt (Depth × Height)/144 3.84 0.75 −43 0.27 −60 Bottom (Depth × Length)/144 3.50 2 82 0.13 19 Top (Length × Depth)/144 3.50 1.5 72 0.13 22 Total Heat Leak Into Cabinet 27 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 91 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 65 0.13 18 Height)/144 Back (Length × Height)/144 4.34 2 65 0.13 18 Side Rt (Depth × Height)/144 5.08 2 65 0.13 21 Side Lt (Depth × Height)/144 3.84 0.75 −7 0.27 −10 Bottom (Depth × Length)/144 3.75 2 75 0.13 18 Top (Length × Depth)/144 3.75 1.5 65 0.13 21 Total Heat Leak Into Cabinet 88 ALLOWANCE FOR DOOR 40 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 147 TOTAL CABINET LOAD 630 (BTU/HR) Example 14 The following tables illustrate the performance of a refrigeration cabinet 34 with three cooling zones 35 and three doors 33 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 13, except that the heat transfer substance 50 is ½ inch thick Armaflex. TABLE 40 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 215 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 333 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 32 0.13 9 Height)/144 Back (Length × Height)/144 4.45 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 0.5 7 0.13 7 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 3.50 2 42 0.13 10 Top (Length × Depth)/144 3.50 1.5 32 0.13 10 Total Heat Leak Into Cabinet −44 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 0 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 25 0.13 7 Height)/144 Back (Length × Height)/144 4.34 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 3.75 2 35 0.13 9 Top (Length × Depth)/144 3.75 1.5 25 0.13 8 Total Heat Leak Into Cabinet 24 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 63 TOTAL CABINET LOAD 396 (BTU/HR) TABLE 41 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 247 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 380 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 52 0.13 15 Height)/144 Back (Length × Height)/144 4.45 2 52 0.13 15 Side Rt (Depth × Height)/144 3.84 0.5 7 0.13 7 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 3.50 2 62 0.13 14 Top (Length × Depth)/144 3.50 1.5 52 0.13 16 Total Heat Leak Into Cabinet −22 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 32 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 45 0.13 13 Height)/144 Back (Length × Height)/144 4.34 2 45 0.13 13 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 3.75 2 55 0.13 13 Top (Length × Depth)/144 3.75 1.5 45 0.13 15 Total Heat Leak Into Cabinet 54 ALLOWANCE FOR DOOR 30 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 103 TOTAL CABINET LOAD 514 (BTU/HR) TABLE 42 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 0.5 43 0.27 89 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 278 ALLOWANCE FOR DOOR 75 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 421 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 72 0.13 21 Height)/144 Back (Length × Height)/144 4.45 2 72 0.13 21 Side Rt (Depth × Height)/144 3.84 0.5 7 0.13 7 Side Lt (Depth × Height)/144 3.84 0.5 −43 0.27 −89 Bottom (Depth × Length)/144 3.50 2 82 0.13 19 Top (Length × Depth)/144 3.50 1.5 72 0.13 22 Total Heat Leak Into Cabinet 0 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 64 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 65 0.13 18 Height)/144 Back (Length × Height)/144 4.34 2 65 0.13 18 Side Rt (Depth × Height)/144 5.08 2 65 0.13 21 Side Lt (Depth × Height)/144 3.84 0.5 −7 0.27 −15 Bottom (Depth × Length)/144 3.75 2 75 0.13 18 Top (Length × Depth)/144 3.75 1.5 65 0.13 21 Total Heat Leak Into Cabinet 83 ALLOWANCE FOR DOOR 40 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 142 TOTAL CABINET LOAD 627 (BTU/HR) Example 15 The following tables illustrate the performance of a refrigeration cabinet 34 with three cooling zones 35 and three doors 33 when the refrigeration cabinet 34 is surrounded by various ambient temperature conditions. This refrigeration cabinet 34 has the same external and internal dimensions as the cabinet of Example 13, except that the heat transfer substance 50 is one inch thick Armaflex. TABLE 43 70° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 75 0.13 25 Height)/144 Back (Length × Height)/144 4.25 2 75 0.13 21 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 75 0.13 23 Bottom (Depth × Length)/144 4.81 2 100 0.13 31 Top (Length × Depth)/144 4.00 1.5 75 0.13 26 Total Heat Leak Into Cabinet 171 ALLOWANCE FOR DOOR 50 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 289 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 32 0.13 9 Height)/144 Back (Length × Height)/144 4.45 2 32 0.13 9 Side Rt (Depth × Height)/144 3.84 1 7 0.13 3 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 3.50 2 42 0.13 10 Top (Length × Depth)/144 3.50 1.5 32 0.13 10 Total Heat Leak Into Cabinet −3 ALLOWANCE FOR DOOR 25 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 41 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 25 0.13 7 Height)/144 Back (Length × Height)/144 4.34 2 25 0.13 7 Side Rt (Depth × Height)/144 5.08 2 25 0.13 8 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 3.75 2 35 0.13 9 Top (Length × Depth)/144 3.75 1.5 25 0.13 8 Total Heat Leak Into Cabinet 32 ALLOWANCE FOR DOOR 20 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 71 TOTAL CABINET LOAD 400 (BTU/HR) TABLE 44 90° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 95 0.13 31 Height)/144 Back (Length × Height)/144 4.25 2 95 0.13 26 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 95 0.13 30 Bottom (Depth × Length)/144 4.81 2 120 0.13 38 Top (Length × Depth)/144 4.00 1.5 95 0.13 33 Total Heat Leak Into Cabinet 202 ALLOWANCE FOR DOOR 65 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 335 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 52 0.13 15 Height)/144 Back (Length × Height)/144 4.45 2 52 0.13 15 Side Rt (Depth × Height)/144 3.84 1 7 0.13 3 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 3.50 2 62 0.13 14 Top (Length × Depth)/144 3.50 1.5 52 0.13 16 Total Heat Leak Into Cabinet 19 ALLOWANCE FOR DOOR 35 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 73 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 45 0.13 13 Height)/144 Back (Length × Height)/144 4.34 2 45 0.13 13 Side Rt (Depth × Height)/144 5.08 2 45 0.13 15 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 3.75 2 55 0.13 13 Top (Length × Depth)/144 3.75 1.5 45 0.13 15 Total Heat Leak Into Cabinet 61 ALLOWANCE FOR DOOR 30 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 110 TOTAL CABINET LOAD 518 (BTU/HR) TABLE 45 110° F. ambient temperature conditions MODEL Length Depth Height Bottom Step Internal 68″ 20.5 26.5 4.875″ × 8.625″ External 72″ 24″ 30.5 Wall MODEL (Outside Dimensions) Sq Ft Thickness Delta T K-Factor BTU/HR FREEZER SIDE Front (Door)(Length × 5.08 2 115 0.13 38 Height)/144 Back (Length × Height)/144 4.25 2 115 0.13 32 Side Rt (Depth × Height)/144 3.84 1 43 0.27 45 Side Lt (Depth × Height)/144 4.79 2 115 0.13 36 Bottom (Depth × Length)/144 4.81 2 140 0.13 44 Top (Length × Depth)/144 4.00 1.5 115 0.13 40 Total Heat Leak Into Cabinet 234 ALLOWANCE FOR DOOR 75 (BTU/HR) FAN INPUT (BTU/HR) 38 ALLOWANCE FOR HEATERS 30 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total FREEZER Load BTU/HR 377 REFRIGERATOR SIDE Front (Door)(Length × 4.45 2 72 0.13 21 Height)/144 Back (Length × Height)/144 4.45 2 72 0.13 21 Side Rt (Depth × Height)/144 3.84 1 7 0.13 3 Side Lt (Depth × Height)/144 3.84 1 −43 0.27 −45 Bottom (Depth × Length)/144 3.50 2 82 0.13 19 Top (Length × Depth)/144 3.50 1.5 72 0.13 22 Total Heat Leak Into Cabinet 41 ALLOWANCE FOR DOOR 45 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total REFRIGERATOR Load 105 BTU/HR CHILLER SIDE Front (Door)(Length × 4.34 2 65 0.13 18 Height)/144 Back (Length × Height)/144 4.34 2 65 0.13 18 Side Rt (Depth × Height)/144 5.08 2 65 0.13 21 Side Lt (Depth × Height)/144 3.84 1 −7 0.27 −7 Bottom (Depth × Length)/144 3.75 2 75 0.13 18 Top (Length × Depth)/144 3.75 1.5 65 0.13 21 Total Heat Leak Into Cabinet 90 ALLOWANCE FOR DOOR 40 (BTU/HR) FAN INPUT (BTU/HR) 19 ALLOWANCE FOR HEATERS 0 *(BTU/HR) LIGHT INPUT (BTU/HR) 0 Total CHILLER Load BTU/HR 149 TOTAL CABINET LOAD 631 (BTU/HR) The following tables summarize the performance capabilities of the refrigeration systems of the above discussed examples, Examples 1-15. The following tables show the BTU/hour required to maintained specific sections at predetermined temperatures and the total BTU/hour consumed by a cabinet housing such sections. The following tables show this information when the cabinet uses three different thicknesses of heat transfer substance and when the cabinet is positioned in three different ambient temperatures. TABLE 46 Performance for the freezer/refrigerator combination of Examples 1-3 where the freezer and refrigerator sections each have a single door and are about the same size. The freezer section is maintained between about −5° F. and 5° F. and the refrigerator section is maintained between about 34° F. and 38° F. Ambient Thickness of Heat Freezer Load Refrigerator Total Cabinet Temperature Transfer Substance BTU/Hour Load BTU/Hour Load BTU/Hour 70° F. ¾ inch 304 36 340 90° F. ¾ inch 350 77 428 110° F. ¾ inch 397 118 515 70° F. ½ inch 333 7 340 90° F. ½ inch 380 48 428 110° F. ½ inch 426 88 515 70° F. 1 inch 289 51 340 90° F. 1 inch 335 92 428 110° F. 1 inch 382 133 515 TABLE 47 Performance for the refrigerator/chiller combination of Examples 4-6 where the refrigerator and chiller sections each have a single door and are about the same size. The refrigerator section is maintained between about 34° F. and 38° F. and the chiller section is maintained at about 45° F. Ambient Thickness of Heat Refrigerator Load Chiller Load Total Cabinet Temperature Transfer Substance BTU/Hour BTU/Hour Load BTU/Hour 70° F. ¾ inch 110 71 181 90° F. ¾ inch 231 116 347 110° F. ¾ inch 278 157 435 70° F. ½ inch 115 66 181 90° F. ½ inch 236 112 347 110° F. ½ inch 282 155 438 70° F. 1 inch 108 73 181 90° F. 1 inch 229 119 347 110° F. 1 inch 275 160 435 TABLE 48 Performance for the refrigerator/chiller combination of Examples 7-9 where refrigerator and chiller sections each have a single door and are about the same size. The refrigerator section is maintained between about 34° F. and 38° F. and the chiller section is maintained at about 65° F. Ambient Thickness of Heat Refrigerator Load Chiller Load Total Cabinet Temperature Transfer Substance BTU/Hour BTU/Hour Load BTU/Hour 70° F. ¾ inch 138 2 140 90° F. ¾ inch 180 38 217 110° F. ¾ inch 221 74 295 70° F. ½ inch 157 −17 140 90° F. ½ inch 198 19 217 110° F. ½ inch 240 55 295 70° F. 1 inch 129 11 140 90° F. 1 inch 170 47 217 110° F. 1 inch 212 83 295 TABLE 49 Performance for the freezer/refrigerator combination of Examples 10-12 where the freezer section has one door and the refrigerator section has two doors and is about twice the size of the freezer section. The freezer section is maintained between about −5° F. and 5° F. and the refrigerator section is maintained between about 34° F. and 38° F. Ambient Thickness of Heat Freezer Load Refrigerator Total Cabinet Temperature Transfer Substance BTU/Hour Load BTU/Hour Load BTU/Hour 70° F. ¾ inch 304 106 410 90° F. ¾ inch 350 184 534 110° F. ¾ inch 397 261 658 70° F. ½ inch 333 77 410 90° F. ½ inch 380 154 534 110° F. ½ inch 426 231 658 70° F. 1 inch 289 121 410 90° F. 1 inch 335 199 534 110° F. 1 inch 382 276 658 TABLE 50 Performance for the freezer/refrigerator/chiller combination of Examples 13-15. The freezer, refrigerator, and chiller sections each have a single door and are about the same size. The freezer section is maintained between about −5° F. and 5° F., the refrigerator section is maintained between about 34° F. and 38° F., and the chiller section is maintained at about 45° F. Thickness of Refrigerator Chiller Total Cabinet Ambient Heat Transfer Freezer Load Load Load Load Temperature Substance BTU/Hour BTU/Hour BTU/Hour BTU/Hour 70° F. ¾ inch 304 27 68 399 90° F. ¾ inch 350 59 108 517 110° F. ¾ inch 392 91 147 630 70° F. ½ inch 333 0 63 396 90° F. ½ inch 380 32 103 514 110° F. ½ inch 421 64 142 627 70° F. 1 inch 289 41 71 400 90° F. 1 inch 335 73 110 518 110° F. 1 inch 377 105 149 631 The refrigeration system of the present invention may have other applications aside from use in connection with food and beverage articles and the invention may be implemented in a variety of configurations, using certain features or aspects of the several embodiments described herein and others known in the art. Thus, although the invention has been herein shown and described in what is perceived to be the most practical and preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific features and embodiments set forth above. Rather, it is recognized that modifications may be made by one of skill in the art of the invention without departing from the spirit or intent of the invention and, therefore, the invention is to be taken as including all reasonable equivalents to the subject matter of the claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>This invention relates generally to a refrigeration system and components thereof, and in particular, to a system having different temperature zones for cooling various food and beverage articles. People have used refrigerated devices to cool and freeze food and beverage articles for many years. Traditionally, these devices utilize a compressor functionally connected to an insulated container. The compressor and associated components and piping change the pressure of refrigerant to absorb heat from the insulated container. A fan system circulates air into and inside the insulated container. A temperature control device is typically connected to the compressor. The temperature control device cycles the compressor on and off as needed to maintain a desired temperature in the insulated container. Cycling a compressor on and off requires a significant amount of energy and results in rather loud noises. Variable capacity compressors have been created to provide a compressor that is continuously operating. The speeds of the compressor can be varied substantially and continuously over a wide range of predefined speeds. Such compressors are disclosed in U.S. Pat. Nos. RE 33,620 to Persem and 4,765,150 to Persem. Operation of variable capacity compressors, like all compressors, results in frost building up on the heat exchange elements. The compressors must be routinely defrosted so that the compressor may operate optimally. One method of defrosting involves running hot gas either through or near the heat exchange elements. Such defrost mechanisms are disclosed in U.S. Pat. Nos. 4,979,371 to Larson; 3,234,754 to Quick; 3,234,753 to Quick; 3,234,748 to Quick; and 3,645,109 to Quick. None of these mechanisms have been designed or utilized with variable capacity compressors. Further, all these mechanisms utilize extensive networks of tubing and control valves to accomplish defrosting. Many refrigeration devices also have different temperature zones. For example, the common home refrigerator has a freezer section and a refrigeration section. Creating different temperatures in different sections of a refrigeration device can be accomplished in at least two methods. One method involves using a different compressor for each section. Another method involves using fans or the like to circulate cold air from a colder section to a warmer section. The operation of the fans may be controlled by a temperature control device. For example, U.S. Pat. No. 4,505,126 to Jones et al. discloses a food product transport system, wherein motorized fans are used to circulate air from one section to another. The fans are positioned in partitions separating the different sections. U.S. Pat. No. 6,000,232 to Witten-Hannah et al. discloses a refrigeration system having a freezer section and a refrigeration section in parallel alignment. This patent further discloses a method wherein motorized fans are used to control the amount of chilled air entering each section. U.S. Pat. No. 5,081,850 to Wakatsuki et al. discloses a refrigerator that has two sections separated by a partition, wherein cool air is circulated throughout the sections and through the partition. All of these devices require the circulation of air from one section to another to create different temperatures in each section. Accordingly, a need exists for an improved refrigeration system and components thereof that solves these and other deficiencies in the prior art. Of course, the present invention may be used in a multitude of situations where similar performance capabilities are required. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a refrigeration system that is cost-effective to manufacture, efficient to operate, relatively quiet when functioning, and overcomes certain of the deficiencies in the prior art. The invention provides for a refrigeration system and components thereof. In one embodiment, the refrigeration system has a container with at least two different temperature cooling zones, which are separated by a divider. The divider has a wall and a partition spaced apart from each other. The partition has a heat transfer plate, which has a sheet with a heat transfer substance attached thereto. In one embodiment, the refrigeration system is cooled by a compressor system having refrigeration and hot-gas defrost modes. A controller controls and selectably operates the compressor system. Preferably, the compressor system has a variable capacity compressor. The present invention also provides for a compressor system, which is a closed system, wherein an evaporator is functionally connected to a variable capacity compressor. The compressor system selectably operates in at least a refrigeration mode and a hot-gas defrost mode. During the hot-gas defrost mode, the evaporator is defrosted by circulation of gas therethrough. In one embodiment, the compressor system has a variable capacity compressor connected to a condenser, which is further connected to a drier, which in turn is connected to a hot-gas by-pass valve and a heat exchanger. The hot-gas by-pass valve and heat exchanger are connected in parallel to one another and are both connected to an evaporator. The evaporator is connected to the variable capacity compressor to form the closed system. A controller may selectably open and close the hot gas bypass valve. While one possible application of the present invention is in connection with residential and commercial refrigeration of food and beverage articles, many other applications are possible and references to use in connection with residential and commercial situations should not be deemed to limit the uses of the present invention. The terms “heat exchanger,” “evaporator,” “condenser,” “capillary tube,” “fan,” “cabinet,” “door,” “damper,” “compressor,” “by-pass valve,” and “heat transfer panel” as used herein should not be interpreted as being limited to specific forms, shapes, numbers, or compositions of a heat exchanger, evaporator, condenser, capillary tube, fan, cabinet, door, damper, compressor, by-pass valve, and heat transfer panel. Rather, the evaporator, condenser, capillary tube, fan, cabinet, door, damper, compressor, by-pass valve, and heat transfer panel may have a wide variety of shapes and forms, may be provided in a wide variety of numbers, and may be composed of a wide variety of materials. These and other objects and advantages of the present invention will become apparent from the detailed description, claims, and accompanying drawings. | 20040401 | 20081118 | 20051006 | 98435.0 | 4 | JONES, MELVIN | REFRIGERATION SYSTEM AND COMPONENTS THEREOF | SMALL | 0 | ACCEPTED | 2,004 |
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10,815,591 | ACCEPTED | Late reverberation-based synthesis of auditory scenes | A scheme for stereo and multi-channel synthesis of inter-channel correlation (ICC) (normalized cross-correlation) cues for parametric stereo and multi-channel coding. The scheme synthesizes ICC cues such that they approximate those of the original. For that purpose, diffuse audio channels are generated and mixed with the transmitted combined (e.g., sum) signal(s). The diffuse audio channels are preferably generated using relatively long filters with exponentially decaying Gaussian impulse responses. Such impulse responses generate diffuse sound similar to late reverberation. An alternative implementation for reduced computational complexity is proposed, where inter-channel level difference (ICLD), inter-channel time difference (ICTD), and ICC synthesis are all carried out in the domain of a single short-time Fourier transform (STFT), including the filtering for diffuse sound generation. | 1. A method for synthesizing an auditory scene, comprising: processing at least one input channel to generate two or more processed input signals; filtering the at least one input channel to generate two or more diffuse signals; and combining the two or more diffuse signals with the two or more processed input signals to generate a plurality of output channels for the auditory scene. 2. The invention of claim 1, wherein processing the at least one input channel comprises: converting the at least one input channel from a time domain into a frequency domain to generate a plurality of frequency-domain (FD) input signals; delaying the FD input signals to generate a plurality of delayed FD signals; and scaling the delayed FD signals to generate a plurality of scaled, delayed FD signals. 3. The invention of claim 2, wherein: the FD input signals are delayed based on inter-channel time difference (ICTD) data; and the delayed FD signals are scaled based on inter-channel level difference (ICLD) and inter-channel correlation (ICC) data. 4. The invention of claim 3, wherein: the at least one input channel is at least one combined channel generated by performing binaural cue coding (BCC) on an original auditory scene; and the ICTD, ICLD, and ICC data are cue codes derived during the BCC coding of the original auditory scene. 5. The invention of claim 4, wherein the at least one combined channel and the cue codes are transmitted from an audio encoder that performs the BCC coding of the original auditory scene. 6. The invention of claim 3, wherein different ICTD, ICLD, and ICC data are applied to different frequency sub-bands of the corresponding FD signals. 7. The invention of claim 2, wherein: the diffuse signals are FD signals; and the combining comprises, for each output channel: summing one of the scaled, delayed FD signals and a corresponding one of the FD diffuse input signals to generate an FD output signal; and converting the FD output signal from the frequency domain into the time domain to generate the output channel. 8. The invention of claim 7, wherein filtering the at least one input channel comprises: applying two or more late reverberation filters to the at least one input channel to generate a plurality of diffuse channels; converting the diffuse channels from the time domain into the frequency domain to generate a plurality of FD diffuse signals; and scaling the FD diffuse signals to generate a plurality of scaled FD diffuse signals, wherein the scaled FD diffuse signals are combined with the scaled, delayed FD input signals to generate the FD output signals. 9. The invention of claim 8, wherein: the FD diffuse signals are scaled based on ICLD and ICC data; the at least one input channel is at least one combined channel generated by performing BCC coding on an original auditory scene; and the ICLD and ICC data are cue codes derived during the BCC coding of the original auditory scene. 10. The invention of claim 9, wherein the at least one combined channel and the cue codes are transmitted from an audio encoder that performs the BCC coding of the original auditory scene. 11. The invention of claim 9, wherein different ICLD and ICC data are applied to different frequency sub-bands of the corresponding FD signals. 12. The invention of claim 7, wherein filtering the at least one input channel comprises: applying two or more FD late reverberation filters to the FD input signals to generate a plurality of diffuse FD signals; and scaling the diffuse FD signals to generate a plurality of scaled diffuse FD signals, wherein the scaled diffuse FD signals are combined with the scaled, delayed FD input signals to generate the FD output signals. 13. The invention of claim 12, wherein: the diffuse FD signals are scaled based on ICLD and ICC data; the at least one input channel is at least one combined channel generated by performing BCC coding on an original auditory scene; and the ICLD and ICC data are cue codes derived during the BCC coding of the original auditory scene. 14. The invention of claim 13, wherein different ICLD and ICC data are applied to different frequency sub-bands of the corresponding FD signals. 15. The invention of claim 1, wherein the method generates more than two output channels from the at least one input channel 16. The invention of claim 15, wherein the method synthesizes a surround sound auditory scene. 17. The invention of claim 15, wherein a single input channel is used to synthesize the auditory scene. 18. The invention of claim 1, wherein: the method applies the processing, filtering, and combining for input channel frequencies less than a specified threshold frequency; and the method further applies alternative auditory scene synthesis processing for input channel frequencies greater than the specified threshold frequency. 19. The invention of claim 18, wherein the alternative auditory scene synthesis processing involves coherence-based BCC coding without the filtering that is applied to the input channel frequencies less than the specified threshold frequency. 20. Apparatus for synthesizing an auditory scene, comprising: means for processing at least one input channel to generate two or more processed input signals; means for filtering the at least one input channel to generate two or more diffuse signals; and means for combining the two or more diffuse signals with the two or more processed input signals to generate a plurality of output channels for the auditory scene. 21. Apparatus for synthesizing an auditory scene, comprising: a configuration of at least one time domain to frequency domain (TD-FD) converter and a plurality of filters, the configuration adapted to generate two or more processed FD input signals and two or more diffuse FD signals from at least one TD input channel; two or more combiners adapted to combine the two or more diffuse FD signals with the two or more processed FD input signals to generate a plurality of synthesized FD signals; and two or more frequency domain to time domain (FD-TD) converters adapted to convert the synthesized FD signals into a plurality of TD output channels for the auditory scene. 22. The invention of claim 21, wherein the configuration comprises: a first TD-FD converter adapted to convert the at least one TD input channel into a plurality of FD input signals; a plurality of delay nodes adapted to delay the FD input signals to generate a plurality of delayed FD signals; and a plurality of multipliers adapted to scale the delayed FD signals to generate a plurality of scaled, delayed FD signals. 23. The invention of claim 22, wherein: the delay nodes are adapted to delay the FD input signals based on inter-channel time difference (ICTD) data; and the multipliers are adapted to scale the delayed FD signals based on inter-channel level difference (ICLD) and inter-channel correlation (ICC) data. 24. The invention of claim 23, wherein: the at least one input channel is at least one combined channel generated by performing binaural cue coding (BCC) on an original auditory scene; and the ICTD, ICLD, and ICC data are cue codes derived during the BCC coding of the original auditory scene. 25. The invention of claim 23, wherein the configuration is adapted to apply different ICTD, ICLD, and ICC data to different frequency sub-bands of the corresponding FD signals. 26. The invention of claim 22, wherein the combiners are adapted to sum, for each output channel, one of the scaled, delayed FD signals and a corresponding one of the diffuse FD signals to generate one of the synthesized FD signals. 27. The invention of claim 26, wherein each filter is a TD late reverberation filter adapted to generate a different TD diffuse channel from the at least one TD input channel; the configuration comprises, for each output channel in the auditory scene: another TD-FD converter adapted to convert a corresponding TD diffuse channel into an FD diffuse signal; and an other multiplier adapted to scale the FD diffuse signal to generate a scaled FD diffuse signal, wherein a corresponding combiner is adapted to combine the scaled FD diffuse signal with a corresponding one of the scaled, delayed FD signals to generate one of the synthesized FD signals. 28. The invention of claim 27, wherein: each other multiplier is adapted to scale the FD diffuse signal based on ICLD and ICC data; the at least one input channel is at least one combined channel generated by performing BCC coding on an original auditory scene; and the ICLD and ICC data are cue codes derived during the BCC coding of the original auditory scene. 29. The invention of claim 28, wherein the configuration applies different ICLD and ICC data to different frequency sub-bands of the corresponding FD signals. 30. The invention of claim 26, wherein: each filter is an FD late reverberation filter adapted to generate a different FD diffuse signal from one of the FD input signals; and the configuration further comprises a further plurality of multipliers adapted to scale the FD diffuse signals to generate a plurality of scaled FD diffuse signals, wherein the combiners are adapted to combine the scaled FD diffuse signals with the scaled, delayed FD signals to generate the synthesized FD signals. 31. The invention of claim 30, wherein at least two FD late reverberation filters have different filter lengths. 32. The invention of claim 30, wherein: the FD diffuse signals are scaled based on ICLD and ICC data; the at least one input channel is at least one combined channel generated by performing BCC coding on an original auditory scene; and the ICLD and ICC data are cue codes derived during the BCC coding of the original auditory scene. 33. The invention of claim 32, wherein the configuration applies different ICLD and ICC data to different frequency sub-bands of the corresponding FD signals. 34. The invention of claim 21, wherein the apparatus is adapted to generate more than two output channels from the at least one TD input channel. 35. The invention of claim 34, wherein the apparatus is adapted to synthesize a surround sound auditory scene. 36. The invention of claim 34, wherein the apparatus is adapted to use a single input channel to synthesize the auditory scene. 37. The invention of claim 21, wherein the apparatus comprises one filter for every output channel in the auditory scene. 38. The invention of claim 21, wherein each filter has a substantially random frequency response with a substantially flat spectral envelope. 39. The invention of claim 21, wherein: the apparatus is adapted to generate, combine, and convert for TD input channel frequencies less than a specified threshold frequency; and the apparatus is further adapted to apply alternative auditory scene synthesis processing for TD input channel frequencies greater than the specified threshold frequency. 40. The invention of claim 39, wherein the alternative auditory scene synthesis processing involves coherence-based BCC coding without the filters that are applied to the TD input channel frequencies less than the specified threshold frequency. | CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of the filing date of U.S. provisional application No. 60/544,287, filed on Feb. 12, 2004 as attorney docket no. Faller 12. The subject matter of this application is related to the subject matter of U.S. patent application Ser. No. 09/848,877, filed on May 4, 2001 as attorney docket no. Faller 5 (“the '877 application”), U.S. patent application Ser. No. 10/045,458, filed on Nov. 7, 2001 as attorney docket no. Baumgarte 1-6-8 (“the '458 application”), and U.S. patent application Ser. No. 10/155,437, filed on May 24, 2002 as attorney docket no. Baumgarte 2-10 (“the '437 application”), the teachings of all three of which are incorporated herein by reference. See, also, C. Faller and F. Baumgarte, “Binaural Cue Coding Applied to Stereo and Multi-Channel Audio Compression,” Preprint 112th Conv. Aud. Eng. Soc., May, 2002, the teachings of which are also incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the encoding of audio signals and the subsequent synthesis of auditory scenes from the encoded audio data. 2. Description of the Related Art When a person hears an audio signal (i.e., sounds) generated by a particular audio source, the audio signal will typically arrive at the person's left and right ears at two different times and with two different audio (e.g., decibel) levels, where those different times and levels are functions of the differences in the paths through which the audio signal travels to reach the left and right ears, respectively. The person's brain interprets these differences in time and level to give the person the perception that the received audio signal is being generated by an audio source located at a particular position (e.g., direction and distance) relative to the person. An auditory scene is the net effect of a person simultaneously hearing audio signals generated by one or more different audio sources located at one or more different positions relative to the person. The existence of this processing by the brain can be used to synthesize auditory scenes, where audio signals from one or more different audio sources are purposefully modified to generate left and right audio signals that give the perception that the different audio sources are located at different positions relative to the listener. FIG. 1 shows a high-level block diagram of conventional binaural signal synthesizer 100, which converts a single audio source signal (e.g., a mono signal) into the left and right audio signals of a binaural signal, where a binaural signal is defined to be the two signals received at the eardrums of a listener. In addition to the audio source signal, synthesizer 100 receives a set of spatial cues corresponding to the desired position of the audio source relative to the listener. In typical implementations, the set of spatial cues comprises an inter-channel level difference (ICLD) value (which identifies the difference in audio level between the left and right audio signals as received at the left and right ears, respectively) and an inter-channel time difference (ICTD) value (which identifies the difference in time of arrival between the left and right audio signals as received at the left and right ears, respectively). In addition or as an alternative, some synthesis techniques involve the modeling of a direction-dependent transfer function for sound from the signal source to the eardrums, also referred to as the head-related transfer function (HRTF). See, e.g., J. Blauert, The Psychophysics of Human Sound Localization, MIT Press, 1983, the teachings of which are incorporated herein by reference. Using binaural signal synthesizer 100 of FIG. 1, the mono audio signal generated by a single sound source can be processed such that, when listened to over headphones, the sound source is spatially placed by applying an appropriate set of spatial cues (e.g., ICLD, ICTD, and/or HRTF) to generate the audio signal for each ear. See, e.g., D. R. Begault, 3-D Sound for Virtual Reality and Multimedia, Academic Press, Cambridge, Mass., 1994. Binaural signal synthesizer 100 of FIG. 1 generates the simplest type of auditory scenes: those having a single audio source positioned relative to the listener. More complex auditory scenes comprising two or more audio sources located at different positions relative to the listener can be generated using an auditory scene synthesizer that is essentially implemented using multiple instances of binaural signal synthesizer, where each binaural signal synthesizer instance generates the binaural signal corresponding to a different audio source. Since each different audio source has a different location relative to the listener, a different set of spatial cues is used to generate the binaural audio signal for each different audio source. FIG. 2 shows a high-level block diagram of conventional auditory scene synthesizer 200, which converts a plurality of audio source signals (e.g., a plurality of mono signals) into the left and right audio signals of a single combined binaural signal, using a different set of spatial cues for each different audio source. The left audio signals are then combined (e.g., by simple addition) to generate the left audio signal for the resulting auditory scene, and similarly for the right. One of the applications for auditory scene synthesis is in conferencing. Assume, for example, a desktop conference with multiple participants, each of whom is sitting in front of his or her own personal computer (PC) in a different city. In addition to a PC monitor, each participant's PC is equipped with (1) a microphone that generates a mono audio source signal corresponding to that participant's contribution to the audio portion of the conference and (2) a set of headphones for playing that audio portion. Displayed on each participant's PC monitor is the image of a conference table as viewed from the perspective of a person sitting at one end of the table. Displayed at different locations around the table are real-time video images of the other conference participants. In a conventional mono conferencing system, a server combines the mono signals from all of the participants into a single combined mono signal that is transmitted back to each participant. In order to make more realistic the perception for each participant that he or she is sitting around an actual conference table in a room with the other participants, the server can implement an auditory scene synthesizer, such as synthesizer 200 of FIG. 2, that applies an appropriate set of spatial cues to the mono audio signal from each different participant and then combines the different left and right audio signals to generate left and right audio signals of a single combined binaural signal for the auditory scene. The left and right audio signals for this combined binaural signal are then transmitted to each participant. One of the problems with such conventional stereo conferencing systems relates to transmission bandwidth, since the server has to transmit a left audio signal and a right audio signal to each conference participant. SUMMARY OF THE INVENTION The '877 and '458 applications describe techniques for synthesizing auditory scenes that address the transmission bandwidth problem of the prior art. According to the '877 application, an auditory scene corresponding to multiple audio sources located at different positions relative to the listener is synthesized from a single combined (e.g., mono) audio signal using two or more different sets of auditory scene parameters (e.g., spatial cues such as an inter-channel level difference (ICLD) value, an inter-channel time delay (ICTD) value, and/or a head-related transfer function (HRTF)). As such, in the case of the PC-based conference described previously, a solution can be implemented in which each participant's PC receives only a single mono audio signal corresponding to a combination of the mono audio source signals from all of the participants (plus the different sets of auditory scene parameters). The technique described in the '877 application is based on an assumption that, for those frequency sub-bands in which the energy of the source signal from a particular audio source dominates the energies of all other source signals in the mono audio signal, from the perspective of the perception by the listener, the mono audio signal can be treated as if it corresponded solely to that particular audio source. According to implementations of this technique, the different sets of auditory scene parameters (each corresponding to a particular audio source) are applied to different frequency sub-bands in the mono audio signal to synthesize an auditory scene. The technique described in the '877 application generates an auditory scene from a mono audio signal and two or more different sets of auditory scene parameters. The '877 application describes how the mono audio signal and its corresponding sets of auditory scene parameters are generated. The technique for generating the mono audio signal and its corresponding sets of auditory scene parameters is referred to in this specification as binaural cue coding (BCC). The BCC technique is the same as the perceptual coding of spatial cues (PCSC) technique referred to in the '877 and '458 applications. According to the '458 application, the BCC technique is applied to generate a combined (e.g., mono) audio signal in which the different sets of auditory scene parameters are embedded in the combined audio signal in such a way that the resulting BCC signal can be processed by either a BCC-based decoder or a conventional (i.e., legacy or non-BCC) receiver. When processed by a BCC-based decoder, the BCC-based decoder extracts the embedded auditory scene parameters and applies the auditory scene synthesis technique of the '877 application to generate a binaural (or higher) signal. The auditory scene parameters are embedded in the BCC signal in such a way as to be transparent to a conventional receiver, which processes the BCC signal as if it were a conventional (e.g., mono) audio signal. In this way, the technique described in the '458 application supports the BCC processing of the '877 application by BCC-based decoders, while providing backwards compatibility to enable BCC signals to be processed by conventional receivers in a conventional manner. The BCC techniques described in the '877 and '458 applications effectively reduce transmission bandwidth requirements by converting, at a BCC encoder, a binaural input signal (e.g., left and right audio channels) into a single mono audio channel and a stream of binaural cue coding (BCC) parameters transmitted (either in-band or out-of-band) in parallel with the mono signal. For example, a mono signal can be transmitted with approximately 50-80% of the bit rate otherwise needed for a corresponding two-channel stereo signal. The additional bit rate for the BCC parameters is only a few kbits/sec (i.e., more than an order of magnitude less than an encoded audio channel). At the BCC decoder, left and right channels of a binaural signal are synthesized from the received mono signal and BCC parameters. The coherence of a binaural signal is related to the perceived width of the audio source. The wider the audio source, the lower the coherence between the left and right channels of the resulting binaural signal. For example, the coherence of the binaural signal corresponding to an orchestra spread out over an auditorium stage is typically lower than the coherence of the binaural signal corresponding to a single violin playing solo. In general, an audio signal with lower coherence is usually perceived as more spread out in auditory space. The BCC techniques of the '877 and '458 applications generate binaural signals in which the coherence between the left and right channels approaches the maximum possible value of 1. If the original binaural input signal has less than the maximum coherence, the BCC decoder will not recreate a stereo signal with the same coherence. This results in auditory image errors, mostly by generating too narrow images, which produces a too “dry” acoustic impression. In particular, the left and right output channels will have a high coherence, since they are generated from the same mono signal by slowly-varying level modifications in auditory critical bands. A critical band model, which divides the auditory range into a discrete number of audio sub-bands, is used in psychoacoustics to explain the spectral integration of the auditory system. For headphone playback, the left and right output channels are the left and right ear input signals, respectively. If the ear signals have a high coherence, then the auditory objects contained in the signals will be perceived as very “localized” and they will have only a very small spread in the auditory spatial image. For loudspeaker playback, the loudspeaker signals only indirectly determine the ear signals, since cross-talk from the left loudspeaker to the right ear and from the right loudspeaker to the left ear has to be taken into account. Moreover, room reflections can also play a significant role for the perceived auditory image. However, for loudspeaker playback, the auditory image of highly coherent signals is very narrow and localized, similar to headphone playback. According to the '437 application, the BCC techniques of the '877 and '458 applications are extended to include BCC parameters that are based on the coherence of the input audio signals. The coherence parameters are transmitted from the BCC encoder to a BCC decoder along with the other BCC parameters in parallel with the encoded mono audio signal. The BCC decoder applies the coherence parameters in combination with the other BCC parameters to synthesize an auditory scene (e.g., the left and right channels of a binaural signal) with auditory objects whose perceived widths more accurately match the widths of the auditory objects that generated the original audio signals input to the BCC encoder. A problem related to the narrow image width of auditory objects generated by the BCC techniques of the '877 and '458 applications is the sensitivity to inaccurate estimates of the auditory spatial cues (i.e., the BCC parameters). Especially with headphone playback, auditory objects that should be at a stable position in space tend to move randomly. The perception of objects that unintentionally move around can be annoying and substantially degrade the perceived audio quality. This problem substantially if not completely disappears, when embodiments of the '437 application are applied. The coherence-based technique of the '437 application tends to work better at relatively high frequencies than at relatively low frequencies. According to certain embodiments of the present invention, the coherence-based technique of the '437 application is replaced by a reverberation technique for one or more—and possibly all—frequency sub-bands. In one hybrid embodiment, the reverberation technique is implemented for low frequencies (e.g., frequency sub-bands less than a specified (e.g., empirically determined) threshold frequency), while the coherence-based technique of the '437 application is implemented for high frequencies (e.g., frequency sub-bands greater than the threshold frequency). In one embodiment, the present invention is a method for synthesizing an auditory scene. At least one input channel is processed to generate two or more processed input signals, and the at least one input channel is filtered to generate two or more diffuse signals. The two or more diffuse signals are combined with the two or more processed input signals to generate a plurality of output channels for the auditory scene. In another embodiment, the present invention is an apparatus for synthesizing an auditory scene. The apparatus includes a configuration of at least one time domain to frequency domain (TD-FD) converter and a plurality of filters, where the configuration is adapted to generate two or more processed FD input signals and two or more diffuse FD signals from at least one TD input channel. The apparatus also has (a) two or more combiners adapted to combine the two or more diffuse FD signals with the two or more processed FD input signals to generate a plurality of synthesized FD signals and (b) two or more frequency domain to time domain (FD-TD) converters adapted to convert the synthesized FD signals into a plurality of TD output channels for the auditory scene. BRIEF DESCRIPTION OF THE DRAWINGS Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which: FIG. 1 shows a high-level block diagram of conventional binaural signal synthesizer that converts a single audio source signal (e.g., a mono signal) into the left and right audio signals of a binaural signal; FIG. 2 shows a high-level block diagram of conventional auditory scene synthesizer that converts a plurality of audio source signals (e.g., a plurality of mono signals) into the left and right audio signals of a single combined binaural signal; FIG. 3 shows a block diagram of an audio processing system that performs binaural cue coding (BCC); FIG. 4 shows a block diagram of that portion of the processing of the BCC analyzer of FIG. 3 corresponding to the generation of coherence measures, according to one embodiment of the '437 application; FIG. 5 shows a block diagram of the audio processing performed by one embodiment of the BCC synthesizer of FIG. 3 to convert a single combined channel into two or more synthesized audio output channels using coherence-based audio synthesis; FIGS. 6(A)-(E) illustrate the perception of signals with different cue codes; FIG. 7 shows a block diagram of the audio processing performed by the BCC synthesizer of FIG. 3 to convert a single combined channel into (at least) two synthesized audio output channels using reverberation-based audio synthesis, according to one embodiment of the present invention; FIGS. 8-10 represents an exemplary five-channel audio system; FIGS. 11 and 12 graphically illustrate the timing of late reverberation filtering and DFT transforms; and FIG. 13 shows a block diagram of the audio processing performed by the BCC synthesizer of FIG. 3 to convert a single combined channel into two synthesized audio output channels using reverberation-based audio synthesis, according to an alternative embodiment of the present invention, in which LR processing is implemented in the frequency domain. DETAILED DESCRIPTION BCC-Based Audio Processing FIG. 3 shows a block diagram of an audio processing system 300 that performs binaural cue coding (BCC). BCC system 300 has a BCC encoder 302 that receives C audio input channels 308, one from each of C different microphones 306, for example, distributed at different positions within a concert hall. BCC encoder 302 has a downmixer 310, which converts (e.g., averages) the C audio input channels into one or more, but fewer than C, combined channels 312. In addition, BCC encoder 302 has a BCC analyzer 314, which generates BCC cue code data stream 316 for the C input channels. In one possible implementation, the BCC cue codes include inter-channel level difference (ICLD), inter-channel time difference (ICTD), and inter-channel correlation (ICC) data for each input channel. BCC analyzer 314 preferably performs band-based processing analogous to that described in the '877 and '458 applications to generate ICLD and ICTD data for each of one or more different frequency sub-bands of the audio input channels. In addition, BCC analyzer 314 preferably generates coherence measures as the ICC data for each frequency sub-band. These coherence measures are described in greater detail in the next section of this specification. BCC encoder 302 transmits the one or more combined channels 312 and the BCC cue code data stream 316 (e.g., as either in-band or out-of-band side information with respect to the combined channels) to a BCC decoder 304 of BCC system 300. BCC decoder 304 has a side-information processor 318, which processes data stream 316 to recover the BCC cue codes 320 (e.g., ICLD, ICTD, and ICC data). BCC decoder 304 also has a BCC synthesizer 322, which uses the recovered BCC cue codes 320 to synthesize C audio output channels 324 from the one or more combined channels 312 for rendering by C loudspeakers 326, respectively. The definition of transmission of data from BCC encoder 302 to BCC decoder 304 will depend on the particular application of audio processing system 300. For example, in some applications, such as live broadcasts of music concerts, transmission may involve real-time transmission of the data for immediate playback at a remote location. In other applications, “transmission” may involve storage of the data onto CDs or other suitable storage media for subsequent (i.e., non-real-time) playback. Of course, other applications may also be possible. In one possible application of audio processing system 300, BCC encoder 302 converts the six audio input channels of conventional 5.1 surround sound (i.e., five regular audio channels+one low-frequency effects (LFE) channel, also known as the subwoofer channel) into a single combined channel 312 and corresponding BCC cue codes 316, and BCC decoder 304 generates synthesized 5.1 surround sound (i.e., five synthesized regular audio channels+one synthesized LFE channel) from the single combined channel 312 and BCC cue codes 316. Many other applications, including 7.1 surround sound or 10.2 surround sound, are also possible. Furthermore, although the C input channels can be downmixed to a single combined channel 312, in alternative implementations, the C input channels can be downmixed to two or more different combined channels, depending on the particular audio processing application. In some applications, when downmixing generates two combined channels, the combined channel data can be transmitted using conventional stereo audio transmission mechanisms. This, in turn, can provide backwards compatibility, where the two BCC combined channels are played back using conventional (i.e., non-BCC-based) stereo decoders. Analogous backwards compatibility can be provided for a mono decoder when a single BCC combined channel is generated. Although BCC system 300 can have the same number of audio input channels as audio output channels, in alternative embodiments, the number of input channels could be either greater than or less than the number of output channels, depending on the particular application. Depending on the particular implementation, the various signals received and generated by both BCC encoder 302 and BCC decoder 304 of FIG. 3 may be any suitable combination of analog and/or digital signals, including all analog or all digital. Although not shown in FIG. 3, those skilled in the art will appreciate that the one or more combined channels 312 and the BCC cue code data stream 316 may be further encoded by BCC encoder 302 and correspondingly decoded by BCC decoder 304, for example, based on some appropriate compression scheme (e.g., ADPCM) to further reduce the size of the transmitted data. Coherence Estimation FIG. 4 shows a block diagram of that portion of the processing of BCC analyzer 314 of FIG. 3 corresponding to the generation of coherence measures, according to one embodiment of the '437 application. As shown in FIG. 4, BCC analyzer 314 comprises two time-frequency (TF) transform blocks 402 and 404, which apply a suitable transform, such as a short-time discrete Fourier transform (DFT) of length 1024, to convert left and right input audio channels L and R, respectively, from the time domain into the frequency domain. Each transform block generates a number of outputs corresponding to different frequency sub-bands of the input audio channels. Coherence estimator 406 characterizes the coherence of each of the different considered critical bands (denoted sub-bands in the following). Those skilled in the art will appreciate that, in preferred DFT-based implementations, the number of DFT coefficients considered as one critical band varies from critical band to critical band with lower-frequency critical bands typically having fewer coefficients than higher-frequency critical bands. In one implementation, the coherence of each DFT coefficient is estimated. The real and imaginary parts of the spectral component KL of the left channel DFT spectrum may be denoted Re{KL} and Im{KL}, respectively, and analogously for the right channel. In that case, the power estimates PLL and PRR for the left and right channels may be represented by Equations (1) and (2), respectively, as follows: PLL=(1−α)PLL+α(Re2{KL}+Im2{KL}) (1) PRR=(1−α)PRR+α(Re2{KR}+Im2{KR}) (2) The real and imaginary cross terms PLR,Re and PLR,Im are given by Equations (3) and (4), respectively, as follows: PLR,Re=(1−α)PLR+α(Re{KL}Re{KR}−Im{KL}Im{KR}) (3) PLR,Im=(1−α)PLR+α(Re{KL}Im{KR}+Im{KL}Re{KR}) (4) The factor α determines the estimation window duration and can be chosen as α=0.1 for an audio sampling rate of 32 kHz and a frame shift of 512 samples. As derived from Equations (1)-(4), the coherence estimate γ for a sub-band is given by Equation (5) as follows: γ{square root}{square root over ((PLR,Re2+PLR,Im2)/(PLLPRR))} (5) As mentioned previously, coherence estimator 406 averages the coefficient coherence estimates γ over each critical band. For that averaging, a weighting function is preferably applied to the sub-band coherence estimates before averaging. The weighting can be made proportional to the power estimates given by Equations (1) and (2). For one critical band p, which contains the spectral components n1, n1+1, . . . , n2, the averaged weighted coherence {overscore (γ)}p may be calculated using Equation (6) as follows: γ _ p = ∑ n = n1 n2 { ( P LL ( n ) + P RR ( n ) ) γ ( n ) } ∑ n = n1 n2 { ( P LL ( n ) + P RR ( n ) ) } , ( 6 ) where PLL(n), PRR(n), and γ(n) are the left channel power, right channel power, and coherence estimates for spectral coefficient n as given by Equations (1), (2), and (6), respectively. Note that Equations (1)-(6) are all per individual spectral coefficients n. In one possible implementation of BCC encoder 302 of FIG. 3, the averaged weighted coherence estimates {overscore (γ)}p for the different critical bands are generated by BCC analyzer 314 for inclusion in the BCC parameter stream transmitted to BCC decoder 304. Coherence-Based Audio Synthesis FIG. 5 shows a block diagram of the audio processing performed by one embodiment of BCC synthesizer 322 of FIG. 3 to convert a single combined channel 312 (s(n)) into C synthesized audio output channels 324 ({circumflex over (x)}1(n), {circumflex over (x)}2(n), . . . , {circumflex over (x)}C(n)) using coherence-based audio synthesis. In particular, BCC synthesizer 322 has an auditory filter bank (AFB) block 502, which performs a time-frequency (TF) transform (e.g., a fast Fourier transform (FFT)) to convert time-domain combined channel 312 into C copies of a corresponding frequency-domain signal 504 ({tilde over (s)}(k)). Each copy of the frequency-domain signal 504 is delayed at a corresponding delay block 506 based on delay values (di(k)) derived from the corresponding inter-channel time difference (ICTD) data recovered by side-information processor 318 of FIG. 3. Each resulting delayed signal 508 is scaled by a corresponding multiplier 510 based on scale (i.e., gain) factors (αi(k)) derived from the corresponding inter-channel level difference (ICLD) data recovered by side-information processor 318. The resulting scaled signals 512 are applied to coherence processor 514, which applies coherence processing based on ICC coherence data recovered by side-information processor 318 to generate C synthesized frequency-domain signals 516 ({circumflex over ({tilde over (x)})}1(k), {circumflex over ({tilde over (x)})}2(k), . . . , {circumflex over ({tilde over (x)})}3(k)), one for each output channel. Each synthesized frequency-domain signal 516 is then applied to a corresponding inverse AFB (IAFB) block 518 to generate a different time-domain output channel 324 ({circumflex over (x)}i(n)). In a preferred implementation, the processing of each delay block 506, each multiplier 510, and coherence processor 514 is band-based, where potentially different delay values, scale factors, and coherence measures are applied to each different frequency sub-band of each different copy of the frequency-domain signals. Given the estimated coherence for each sub-band, the magnitude is varied as a function of frequency within the sub-band. Another possibility is to vary the phase as a function of frequency in the partition as a function of the estimated coherence. In a preferred implementation, the phase is varied such as to impose different delays or group delays as a function of frequency within the sub-band. Also, preferably the magnitude and/or delay (or group delay) variations are carried out such that, in each critical band, the mean of the modification is zero. As a result, ICLD and ICTD within the sub-band are not changed by the coherence synthesis. In preferred implementations, the amplitude g (or variance) of the introduced magnitude or phase variation is controlled based on the estimated coherence of the left and right channels. For a smaller coherence, the gain g should be properly mapped as a suitable function ƒ(γ) of the coherence γ. In general, if the coherence is large (e.g., approaching the maximum possible value of +1), then the object in the input auditory scene is narrow. In that case, the gain g should be small (e.g., approaching the minimum possible value of 0) so that there is effectively no magnitude or phase modification within the sub-band. On the other hand, if the coherence is small (e.g., approaching the minimum possible value of 0), then the object in the input auditory scene is wide. In that case, the gain g should be large, such that there is significant magnitude and/or phase modification resulting in low coherence between the modified sub-band signals. A suitable mapping function ƒ(γ) for the amplitude g for a particular critical band is given by Equation (7) as follows: g=5(1−{overscore (γ)}) (7) where {overscore (γ)} is the estimated coherence for the corresponding critical band that is transmitted to BCC decoder 304 of FIG. 3 as part of the stream of BCC parameters. According to this linear mapping function, the gain g is 0 when the estimated coherence {overscore (γ)} is 1, and g=5, when {overscore (γ)}=0. In alternative embodiments, the gain g may be a non-linear function of coherence. Although coherence-based audio synthesis has been described in the context of modifying the weighting factors wL and wR based on a pseudo-random sequence, the technique is not so limited. In general, coherence-based audio synthesis applies to any modification of perceptual spatial cues between sub-bands of a larger (e.g., critical) band. The modification function is not limited to random sequences. For example, the modification function could be based on a sinusoidal function, where the ICLD (of Equation (9)) is varied in a sinusoidal way as a function of frequency within the sub-band. In some implementations, the period of the sine wave varies from critical band to critical band as a function of the width of the corresponding critical band (e.g., with one or more full periods of the corresponding sine wave within each critical band). In other implementations, the period of the sine wave is constant over the entire frequency range. In both of these implementations, the sinusoidal modification function is preferably contiguous between critical bands. Another example of a modification function is a sawtooth or triangular function that ramps up and down linearly between a positive maximum value and a corresponding negative minimum value. Here, too, depending on the implementation, the period of the modification function may vary from critical band to critical band or be constant across the entire frequency range, but, in any case, is preferably contiguous between critical bands. Although coherence-based audio synthesis has been described in the context of random, sinusoidal, and triangular functions, other functions that modify the weighting factors within each critical band are also possible. Like the sinusoidal and triangular functions, these other modification functions may be, but do not have to be, contiguous between critical bands. According to the embodiments of coherence-based audio synthesis described above, spatial rendering capability is achieved by introducing modified level differences between sub-bands within critical bands of the audio signal. Alternatively or in addition, coherence-based audio synthesis can be applied to modify time differences as valid perceptual spatial cues. In particular, a technique to create a wider spatial image of an auditory object similar to that described above for level differences can be applied to time differences, as follows. As defined in the '877 and '458 applications, the time difference in sub-band s between two audio channels is denoted τs. According to certain implementations of coherence-based audio synthesis, a delay offset ds and a gain factor gc can be introduced to generate a modified time difference τs′ for sub-band s according to Equation (8) as follows. τs′=gcds+τs (8) The delay offset ds is preferably constant over time for each sub-band, but varies between sub-bands and can be chosen as a zero-mean random sequence or a smoother function that preferably has a mean value of zero in each critical band. As with the gain factor g in Equation (9), the same gain factor gc is applied to all sub-bands n that fall inside each critical band c, but the gain factor can vary from critical band to critical band. The gain factor gc is derived from the coherence estimate using a mapping function that is preferably proportional to linear mapping function of Equation (7). As such, gc=ag, where the value of constant a is determined by experimental tuning. In alternative embodiments, the gain gc may be a non-linear function of coherence. BCC synthesizer 322 applies the modified time differences τs′ instead of the original time differences τs. To increase the image width of an auditory object, both level-difference and time-difference modifications can be applied. Although coherence-based processing has been described in the context of generating the left and right channels of a stereo audio scene, the techniques can be extended to any arbitrary number of synthesized output channels. Reverberation-Based Audio Synthesis DEFINITIONS, NOTATION, AND VARIABLES The following measures are used for ICLD, ICTD, and ICC for corresponding frequency-domain input sub-band signals {tilde over (x)}1(k) and {tilde over (x)}2(k) of two audio channels with time index k: ICLD (dB): Δ L 12 ( k ) = 10 log 10 ( p x ~ 2 ( k ) p x ~ 1 ( k ) ) , ( 9 ) where p{tilde over (x)}1(k) and p{tilde over (x)}2(k) are short-time estimates of the power of the signals {tilde over (x)}1(k) and {tilde over (x)}2(k), respectively. ICTD (samples): τ 12 ( k ) = arg max d { Φ 12 ( d , k ) } , ( 10 ) with a short-time estimate of the normalized cross-correlation function Φ 12 ( d , k ) = p x ~ 1 x ~ 2 ( d , k ) p x ~ 1 ( k - d 1 ) p x ~ 2 ( k - d 2 ) ( 11 ) where d 1 = max { - d , 0 } d 2 = max { d , 0 } , ( 12 ) and p{tilde over (x)}1{tilde over (x)}2(d, k) is a short-time estimate of the mean of {tilde over (x)}1(k−d1){tilde over (x)}2(k−d2) ICC: c 12 ( k ) = max d Φ 12 ( d , k ) . ( 13 ) Note that the absolute value of the normalized cross-correlation is considered and c12(k) has a range of [0,1]. There is no need to consider negative values, since ICTD contains the phase information represented by the sign of c12(k). The following notation and variables are used in this specification: * convolution operator i audio channel index k time index of sub-band signals (also time index of STFT spectra) C number of encoder input channels, also number of decoder output channels xi(n) time-domain encoder input audio channel (e.g., one of channels 308 of FIG. 3) {tilde over (x)}i(k) one frequency-domain sub-band signal of xi(n) (e.g., one of the outputs from TF transform 402 or 404 of FIG. 4) s(n) transmitted time-domain combined channel (e.g., sum channel 312 of FIG. 3) {tilde over (s)}(k) one frequency-domain sub-band signal of s(n) (e.g., signal 704 of FIG. 7) si(n) de-correlated time-domain combined channel (e.g., a filtered channel 722 of FIG. 7) {tilde over (s)}i(k) one frequency-domain sub-band signal of si(n) (e.g., a corresponding signal 726 of FIG. 7) {circumflex over (x)}i(n) time-domain decoder output audio channel (e.g., a signal 324 of FIG. 3) {circumflex over ({tilde over (x)})}i(k) one frequency-domain sub-band signal of {circumflex over (x)}i(n) (e.g., a corresponding signal 716 of FIG. 7) p{tilde over (x)}i(k) short-time estimate of power of {tilde over (x)}i(k) hi(n) late reverberation (LR) filter for output channel i (e.g., an LR filter 720 of FIG. 7) M length of LR filters hi(n) ICLD inter-channel level difference ICTD inter-channel time difference ICC inter-channel correlation ΔL1i(k) ICLD between channel 1 and channel i τ1i(k) ICTD between channel 1 and channel i c1i(k) ICC between channel 1 and channel i STFT short-time Fourier transform Xk(jω) STFT spectrum of a signal Perception of ICLD, ICTD, and ICC FIGS. 6(A)-(E) illustrate the perception of signals with different cue codes. In particular, FIG. 6(A) shows how the ICLD and ICTD between a pair of loudspeaker signals determine the perceived angle of an auditory event. FIG. 6(B) shows how the ICLD and ICTD between a pair of headphone signals determine the location of an auditory event that appears in the frontal section of the upper head. FIG. 6(C) shows how the extent of the auditory event increases (from region 1 to region 3) as the ICC between the loudspeaker signals decreases. FIG. 6(D) shows how the extent of the auditory object increases (from region 1 to region 3) as the ICC between left and right headphone signals decreases, until two distinct auditory events appear at the sides (region 4). FIG. 6(E) shows how, for multi-loudspeaker playback, the auditory event surrounding the listener increases in extent (from region 1 to region 4) as the ICC between the signals decreases. Coherent Signals (ICC=1) FIGS. 6(A) and 6(B) illustrate perceived auditory events for different ICLD and ICTD values for coherent loudspeaker and headphone signals. Amplitude panning is the most commonly used technique for rendering audio signals for loudspeaker and headphone playback. When left and right loudspeaker or headphone signals are coherent (i.e., ICC=1), have the same level (i.e., ICLD=0), and have no delay (i.e., ICTD=0), an auditory event appears in the center, as illustrated by regions 1 in FIGS. 6(A) and 6(B). Note that auditory events appear, for the loudspeaker playback of FIG. 6(A), between the two loudspeakers and, for the headphone playback of FIG. 6(B), in the frontal section of the upper half of the head. By increasing the level on one side, e.g., right, the auditory event moves to that side, as illustrated by regions 2 in FIGS. 6(A) and 6(B). In the extreme case, e.g., when only the signal on the left is active, the auditory event appears at the left side, as illustrated by regions 3 in FIGS. 6(A) and 6(B). ICTD can similarly be used to control the position of the auditory event. For headphone playback, ICTD can be applied for this purpose. However, ICTD is preferably not used for loudspeaker playback for several reasons. ICTD values are most effective in free-field when the listener is exactly in the sweet spot. In enclosed environments, due the reflections, the ICTD (with a small range, e.g., ±1 ms) will have very little impact on the perceived direction of the auditory event. Partially Coherent Signals (ICC<1) When coherent (ICC=1) wideband sounds are simultaneously emitted by a pair of loudspeakers, a relatively compact auditory event is perceived. When the ICC is reduced between these signals, the extent of the auditory event increases, as illustrated in FIG. 6(C) from region 1 to region 3. For headphone playback, a similar trend can be observed, as illustrated in FIG. 6(D). When two identical signals (ICC=1) are emitted by the headphones, a relatively compact auditory event is perceived, as in region 1. The extent of the auditory event increases, as in regions 2 and 3, as the ICC between the headphone signals decreases, until two distinct auditory events are perceived at the sides, as in region 4. In general, ICLD and ICTD determine the location of the perceived auditory event, and ICC determines the extent or diffuseness of the auditory event. Additionally, there are listening situations, when a listener not only perceives auditory events at a distance, but perceives to be surrounded by diffuse sound. This phenomenon is called listener envelopment. Such a situation occurs for example in a concert hall, where late reverberation arrives at the listener's ears from all directions. A similar experience can be evoked by emitting independent noise signals from loudspeakers distributed all around a listener, as illustrated in FIG. 6(E). In this scenario, there is a relation between ICC and the extent of the auditory event surrounding the listener, as in regions 1 to 4. The perceptions described above can be produced by mixing a number of de-correlated audio channels with low ICC. The following sections describe reverberation-based techniques for producing such effects. Generating Diffuse Sound from a Single Combined Channel As mentioned before, a concert hall is one typical scenario where a listener perceives a sound as diffuse. During late reverberation, sound arrives at the ears from random angles with random strengths, such that the correlation between the two ear input signals is low. This gives a motivation for generating a number of de-correlated audio channels by filtering a given combined audio channel s(n) with filters modeling late reverberation. The resulting filtered channels are also referred to as “diffuse channels” in this specification. C diffuse channels si(n), (1≦i≦C), are obtained by Equation (14) as follows: si(n)=hi(n)*s(n), (14) where * denotes convolution, and hi(n) are the filters modeling late reverberation. Late reverberation can be modeled by Equation (15) as follows: h i ( n ) = { n i ( n ) ( 1 - 1 f s T ) n , 0 ≤ n < M 0 , otherwise , ( 15 ) where ni(n) (1≦i≦C) are independent stationary white Gaussian noise signals, T is the time constant in seconds of the exponential decay of the impulse response in seconds, ƒs is the sampling frequency, and M is the length of the impulse response in samples. An exponential decay is chosen, because the strength of late reverberation typically decays exponentially in time. The reverberation time of many concert halls is in the range of 1.5 to 3.5 seconds. In order for the diffuse audio channels to be independent enough for generating diffuseness of concert hall recordings, T is chosen such that the reverberation times of hi(n) are in the same range. This is the case for T=0.4 seconds (resulting in a reverberation time of about 2.8 seconds). By computing each headphone or loudspeaker signal channel as a weighted sum of s(n) and si(n), (1≦i≦C), signals with desired diffuseness can be generated (with maximum diffuseness similar to a concert hall when only si(n) are used). BCC synthesis preferably applies such processing in each sub-band separately, as is shown in the next section. Exemplary Reverberation-Based Audio Synthesizer FIG. 7 shows a block diagram of the audio processing performed by BCC synthesizer 322 of FIG. 3 to convert a single combined channel 312 (s(n)) into (at least) two synthesized audio output channels 324 ({circumflex over (x)}1(n), {circumflex over (x)}2(n), . . . ) using reverberation-based audio synthesis, according to one embodiment of the present invention. As shown in FIG. 7 and similar to processing in BCC synthesizer 322 of FIG. 5, AFB block 702 converts time-domain combined channel 312 into two copies of a corresponding frequency-domain signal 704 ({tilde over (s)}(k)). Each copy of the frequency-domain signal 704 is delayed at a corresponding delay block 706 based on delay values (di(k)) derived from the corresponding inter-channel time difference (ICTD) data recovered by side-information processor 318 of FIG. 3. Each resulting delayed signal 708 is scaled by a corresponding multiplier 710 based on scale factors (ai(k)) derived from cue code data recovered by side-information processor 318. The derivation of these scale factors is described in further detail below. The resulting scaled, delayed signals 712 are applied to summation nodes 714. In addition to being applied to AFB block 702, copies of combined channel 312 are also applied to late reverberation (LR) processors 720. In some implementations, the LR processors generate a signal similar to the late reverberation that would be evoked in a concert hall if the combined channel 312 were played back in that concert hall. Moreover, the LR processors can be used to generate late reverberation corresponding to different positions in the concert hall, such that their output signals are de-correlated. In that case, combined channel 312 and the diffuse LR output channels 722 (s1(n), s2(n)) would have a high degree of independence (i.e., ICC values close to zero). The diffuse LR channels 722 may be generated by filtering the combined signal 312 as described in the previous section using Equations (14) and (15). Alternatively, the LR processors can be implemented based on any other suitable reverberation technique, such as those described in M. R. Schroeder, “Natural sounding artificial reverberation,” J. Aud. Eng. Soc., vol. 10, no. 3, pp.219-223, 1962, and W. G. Gardner, Applications of Digital Signal Processing to Audio and Acoustics, Kluwer Academic Publishing, Norwell, Mass., USA, 1998, the teachings of both of which are incorporated herein by reference. In general, preferred LR filters are those having a substantially random frequency response with a substantially flat spectral envelope. The diffuse LR channels 722 are applied to AFB blocks 724, which convert the time-domain LR channels 722 into frequency-domain LR signals 726 ({tilde over (s)}1(k), {tilde over (s)}2(k)). AFB blocks 702 and 724 are preferably invertible filter banks with sub-bands having bandwidths equal or proportional to the critical bandwidths of the auditory system. Each sub-band signal for the input signals s(n), s1(n), and s2(n) is denoted {tilde over (s)}(k), {tilde over (s)}1(k), or {tilde over (s)}2(k), respectively. A different time index k is used for the decomposed signals instead of the input channel time index n, since the sub-band signals are usually represented with a lower sampling frequency than the original input channels. Multipliers 728 multiply the frequency-domain LR signals 726 by scale factors (bi(k)) derived from cue code data recovered by side-information processor 318. The derivation of these scale factors is described in further detail below. The resulting scaled LR signals 730 are applied to summation nodes 714. Summation nodes 714 add scaled LR signals 730 from multipliers 728 to the corresponding scaled, delayed signals 712 from multipliers 710 to generate frequency-domain signals 716 ( x ^ ~ 1 ( k ) , x ^ ~ 2 ( k ) ) for the different output channels. The sub-band signals 716 generated at summation nodes 714 are given by Equation (16) as follows: x ^ ~ 1 ( k ) = a 1 s ~ ( k - d 1 ) + b 1 s ~ 1 ( k ) x ^ ~ 2 ( k ) = a 2 s ~ ( k - d 2 ) + b 2 s ~ 2 ( k ) , ( 16 ) where the scale factors (a1,a2,b1,b2) and delays (d1,d2) are determined as functions of the desired ICLD ΔL12(k), ICTD τ12(k), and ICC c12(k). (The time indices of the scale factors and delays are omitted for a simpler notation.). The signals x ^ ~ 1 ( k ) , x ^ ~ 2 ( k ) are generated for all sub-bands. Although the embodiment of FIG. 7 relies on summation nodes to combine the scaled LR signals with the corresponding scaled, delayed signals, in alternative embodiments, combiners other than summation nodes may be used to combine the signals. Examples of alternative combiners include those that perform weighted summation, summation of magnitudes, or selection of maximum values. The ICTD τ12(k) is synthesized by imposing different delays (d1,d2) on {tilde over (s)}(k). These delays are computed by Equation (10) with d=τ12(n). In order for the output sub-band signals to have an ICLD equal to ΔL12(k) of Equation (9), the scale factors (a1,a2,b1,b2) should satisfy Equation (17) as follows: a 1 2 p s ~ ( k ) + b 1 2 p s ~ 1 ( k ) a 2 2 p s ~ ( k ) + b 2 2 p s ~ 2 ( k ) = 10 Δ L 12 ( k ) 10 , ( 17 ) where p{tilde over (s)}(k), p{tilde over (s)}1(k), and p{tilde over (s)}2(k) are the short-time power estimates of the sub-band signals {tilde over (s)}(k), {tilde over (s)}1(k), and {tilde over (s)}2(k), respectively. For the output sub-band signals to have the ICC c12(k) of Equation (13), the scale factors (a1,a2,b1,b2) should satisfy Equation (18) as follows: ( a 1 2 + a 2 2 ) p s ~ ( k ) ( a 1 2 p s ~ ( k ) + b 1 2 p s ~ 1 ( k ) ) ( a 2 2 p s ~ ( k ) + b 2 2 p s ~ 2 ( k ) ) = c 12 ( k ) , ( 18 ) assuming that {tilde over (s)}(k), {tilde over (s)}1(k), and {tilde over (s)}2(k) are independent. Each IAFB block 718 converts a set of frequency-domain signals 716 into a time-domain channel 324 for one of the output channels. Since each LR processor 720 can be used to model late reverberation emanating from different directions in a concert hall, different late reverberation can be modeled for each different loudspeaker 326 of audio processing system 300 of FIG. 3. BCC synthesis usually normalizes its output signals, such that the sum of the powers of all output channels is equal to the power of the input combined signal. This yields another equation for the gain factors: (a12+a12)p{tilde over (s)}(k)+b12p{tilde over (s)}1(k)+b22p{tilde over (s)}2(k)=p{tilde over (s)}(k). (19) Since there are four gain factors and three equations, there is still one degree of freedom in the choice of the gain factors. Thus, an additional condition can be formulated as: b12p{tilde over (s)}1(k)=b22p{tilde over (s)}2(k). (20) Equation (20) implies that the amount of diffuse sound is always the same in the two channels. There are several motivations for doing this. First, diffuse sound as appears in concert halls as late reverberation has a level that is nearly independent of position (for relatively small displacements). Thus, the level difference of the diffuse sound between two channels is always about 0 dB. Second, this has the nice side effect that, when ΔL12(k) is very large, only diffuse sound is mixed into the weaker channel. Thus, the sound of the stronger channel is modified minimally, reducing negative effects of the long convolutions, such as time spreading of transients. Non-negative solutions for Equations (17)-(20) yield the following equations for the scale factors: a 1 = 10 Δ L 12 ( k ) 10 + c 12 ( k ) 10 Δ L 12 ( k ) 20 - 1 2 ( 10 Δ L 12 ( k ) 10 + 1 ) a 2 = - 10 Δ L 12 ( k ) 10 + c 12 ( k ) 10 Δ L 12 ( k ) 20 + 1 2 ( 10 Δ L 12 ( k ) 10 + 1 ) b 1 = ( 10 Δ L 12 ( k ) 10 + c 12 ( k ) - 10 Δ L 12 ( k ) 20 + 1 ) p s ~ ( k ) 2 ( 10 Δ L 12 ( k ) 10 + 1 ) p s ~ 1 ( k ) b 2 = ( 10 Δ L 12 ( k ) 10 + c 12 ( k ) - 10 Δ L 12 ( k ) 20 + 1 ) p s ~ ( k ) 2 ( 10 Δ L 12 ( k ) 10 + 1 ) p s ~ 2 ( k ) ( 21 ) Multi-Channel BCC Synthesis Although the configuration shown in FIG. 7 generates two output channels, the configuration can be extended to any greater number of output channels by replicating the configuration shown in the dashed block in FIG. 7. Note that, in these embodiments of the present invention, there is one LR processor 720 for each output channel. Note further that, in these embodiments, each LR processor is implemented to operate on the combined channel in the time domain. FIG. 8 represents an exemplary five-channel audio system. It is enough to define ICLD and ICTD between a reference channel (e.g., channel number 1) and each of the other four channels, where ΔL1i(k) and τ1i(k) denote the ICLD and ICTD between the reference channel 1 and channel i, 2≦i≦5. As opposed to ICLD and ICTD, ICC has more degrees of freedom. In general, the ICC can have different values between all possible input channel pairs. For C channels, there are C(C−1)/2 possible channel pairs. For example, for five channels, there are ten channel pairs as represented in FIG. 9. Given a sub-band {tilde over (s)}(k) of the combined signal s(n) plus the sub-bands of C−1 diffuse channels {tilde over (s)}i(k), where (1≦i≦C−1) and the diffuse channels are assumed to be independent, it is possible to generate C sub-band signals such that the ICC between each possible channel pair is the same as the ICC estimated in the corresponding sub-bands of the original signal. However, such a scheme would involve estimating and transmitting C(C−1)/2 ICC values for each sub-band at each time index, resulting in relatively high computational complexity and a relatively high bit rate. For each sub-band, the ICLD and ICTD determine the direction at which the auditory event of the corresponding signal component in the sub-band is rendered. Therefore, in principle, it should be enough to just add one ICC parameter, which determines the extent or diffuseness of that auditory event. Thus, in one embodiment, for each sub-band, at each time index k, only one ICC value corresponding to the two channels having the greatest power levels in that sub-band is estimated. This is illustrated in FIG. 10, where, at time instance k−1, the channel pair (3,4) have the greatest power levels for a particular sub-band, while, at time instance k, the channel pair (1,2) have the greatest power levels for the same sub-band. In general, one or more ICC values can be transmitted for each sub-band at each time interval. Similar to the two-channel (e.g., stereo) case, the multi-channel output sub-band signals are computed as weighted sums of the sub-band signals of the combined signal and diffuse audio channels, as follows: x ^ ~ 1 ( k ) = a 1 s ~ ( k - d 1 ) + b 1 s ~ 1 ( k ) x ^ ~ 2 ( k ) = a 2 s ~ ( k - d 2 ) + b 2 s ~ 2 ( k ) ⋮ ⋮ x ^ ~ C ( k ) = a C s ~ ( k - d C ) + b C s ~ C ( k ) . ( 22 ) The delays are determined from the ICTDs as follows: d i = { - min 1 ≤ l < C τ 1 l ( k ) i = 1 τ 1 l ( k ) + d 1 2 ≤ i ≤ C . ( 23 ) 2C equations are needed to determine the 2C scale factors in Equation (22). The following discussion describes the conditions leading to these equations. ICLD: C−1 equations similar to Equation (17) are formulated between the channels pairs such that the output sub-band signals have the desired ICLD cues. ICC for the two strongest channels: Two equations similar to Equations (18) and (20) between the two strongest audio channels, i1 and i2, are formulated such that (1) the ICC between these channels is the same as the ICC estimated in the encoder and (2) the amount of diffuse sound in both channels is the same, respectively. Normalization: Another equation is obtained by extending Equation (19) to C channels, as follows: ∑ i = 1 C a i 2 p s ~ ( k ) + ∑ i = 1 C b i 2 p s ~ i ( k ) = p s ~ ( k ) ( 24 ) ICC for C−2 weakest channels: The ratio between the power of diffuse sound to non-diffuse sound for the weakest C−2 channels (i≠i1{circumflex over ( )}i≠i2 ) is chosen to be the same as for the second strongest channel i2, such that: b i 2 p s ~ i ( k ) a i 2 p s ~ ( k ) = b i 2 2 p s ~ i 2 ( k ) a i 2 2 p s ~ ( k ) , ( 25 ) resulting in another C−2 equations, for a total of 2C equations. The scale factors are the non-negative solutions of the described 2C equations. Reducing Computational Complexity As mentioned before, for reproducing naturally sounding diffuse sound, the impulse responses hi(t) of Equation (15) should be as long as several hundred milliseconds, resulting in high computational complexity. Furthermore, BCC synthesis requires, for each hi(t), (1≦i≦C ), an additional filter bank, as indicated in FIG. 7 The computational complexity could be reduced by using artificial reverberation algorithms for generating late reverberation and using the results for si(t). Another possibility is to carry out the convolutions by applying an algorithm based on the fast Fourier transform (FFT) for reduced computational complexity. Yet another possibility is to carry out the convolutions of Equation (14) in the frequency domain, without introducing an excessive amount of delay. In this case, the same short-time Fourier transform (STFT) with overlapping windows can be used for both the convolutions and the BCC processing. This results in lower computational complexity of the convolution computation and no need to use an additional filter bank for each hi(t). The technique is derived for a single combined signal s(t) and a generic impulse response h(t). The STFT applies discrete Fourier transforms (DFTs) to windowed portions of a signal s(t). The windowing is applied at regular intervals, denoted window hop size N. The resulting windowed signal with window position index k is: s k ( t ) = { w ( t - kN ) s ( t ) , kN ≤ t ≤ kN + W 0 , otherwise , ( 26 ) where W is the window length. A Hann window can be used with length W=512 samples and a window hop size of N=W/2 samples. Other windows can be used that fulfill the (in the following, assumed) condition: s ( t ) = ∑ k = - ∞ ∞ s k ( t ) ( 27 ) First, the simple case of implementing a convolution of the windowed signal sk(t) in the frequency domain is considered. FIG. 11(A) illustrates the non-zero span of an impulse response h(t) of length M. Similarly, the non-zero span of sk(t) is illustrated in FIG. 11(B). It is easy to verify that h(t)*sk(t) has a non-zero span of W+M−1 samples as illustrated in FIG. 11(C). FIGS. 12(A)-(C) illustrate at which time indices DFTs of length W+M−1 are applied to the signals h(t), sk(t), and h(t)*sk(t), respectively. FIG. 12(A) illustrates that H(jω) denotes the spectrum obtained by applying the DFT starting at time index t=0 to h(t). FIGS. 12(B) and 12(C) illustrate the computation of Xk(jω) and Yk(jω) from sk(t) and h(t)*sk(t), respectively, by applying the DFTs starting at time index t=kN. It can easily be shown that Yk(jω)=H(jω)Xk(jω). That is, because the zeros at the end of the signals h(t) and sk(t) result in the circular convolution imposed on the signals by the spectrum product being equal to linear convolution. From the linearity property of convolution and Equation (27), it follows that: h ( t ) * s ( t ) = ∑ k = - ∞ ∞ h ( t ) * s k ( t ) . ( 28 ) Thus, it is possible to implement a convolution in the domain of the STFT by computing, at each time t, the product H(jω)Xk(jω) and applying the inverse STFT (inverse DFT plus overlap/add). A DFT of length W+M−1 (or longer) should be used with zero padding as implied by FIG. 12. The described technique is similar to overlap/add convolution with the generalization that overlapping windows can be used (with any window fulfilling the condition of Equation (27)). The described method is not practical for long impulse responses (e.g., M>>W), since then a DFT of a much larger size than W needs to be used. In the following, the described method is extended such that only a DFT of size W+N−1 needs to be used. A long impulse response h(t) of length M=LN is partitioned into L shorter impulse responses hl(t), where: h l ( t ) = { h ( t + lN ) , 0 ≤ t < N 0 , otherwise ( 29 ) If mod(M, N)≠0, then N−mod(M, N) zeroes are added to the tail of h(t). The convolution with h(t) can then be written as a sum of shorter convolutions, as follows: h ( t ) * s ( t ) = ∑ l = 0 L - 1 h l ( t ) * s ( t - lN ) . ( 30 ) Applying Equations (29) and (30), at the same time, yields: h ( t ) * s ( t ) = ∑ k = - ∞ ∞ ∑ l = 0 L - 1 h l ( t ) * s k ( t - lN ) . ( 31 ) The non-zero time span of one convolution in Equation (31), hl(t)*sk(t−lN), as a function of k and l is (k+l)N≦t<(k+l+1)N+W. Thus, for obtaining its spectrum {tilde over (Y)}kl(jω), the DFT is applied to this interval (corresponding to DFT position index k+1). It can be shown that {tilde over (Y)}kl(jω)=Hl(jω)Xk(jω) where Xk(jω) is defined as previously with M=N, and Hl(jω) is defined similar to H(jω), but for the impulse response hl(t). The sum of all spectra {tilde over (Y)}kl(jω) with the same DFT position index i=k+1 is as follows: Y i ( jω ) = ∑ k + l = i Y ~ k + l ( jω ) = ∑ l = 0 L - 1 H l ( jω ) X i - l ( jω ) . ( 32 ) Thus, the convolution h(t)*sk(t) is implemented in the STFT domain by applying Equation (32) at each spectrum index i to obtain Yi(jω). The inverse STFT (inverse DFT plus overlap/add) applied to Yi(jω) is equal to the convolution as desired. Note that, independently of the length of h(t), the amount of zero padding is upper bounded by N−1 (one sample less than the STFT window hop size). DFTs larger than W+N−1 can be used if desired (e.g., using an FFT with a length equal to a power of two). As mentioned before, low-complexity BCC synthesis can operate in the STFT domain. In this case, ICLD, ICTD, and ICC synthesis is applied to groups of STFT bins representing spectral components with bandwidths equal or proportional to the bandwidth of a critical band (where groups of bins are denoted “partitions”). In such a system, for reduced complexity, instead of applying the inverse STFT to Equation (32), the spectra of Equation (32) are directly used as diffuse sound in the frequency domain. FIG. 13 shows a block diagram of the audio processing performed by BCC synthesizer 322 of FIG. 3 to convert a single combined channel 312 (s(t)) into two synthesized audio output channels 324 ({circumflex over (x)}1(t), {circumflex over (x)}2(t)) using reverberation-based audio synthesis, according to an alternative embodiment of the present invention, in which LR processing is implemented in the frequency domain. In particular, as shown in FIG. 13, AFB block 1302 converts the time-domain combined channel 312 into four copies of a corresponding frequency-domain signal 1304 ({tilde over (s)}(k)). Two of the four copies of the frequency-domain signals 1304 are applied to delay blocks 1306, while the other two copies are applied to LR processors 1320, whose frequency-domain LR output signals 1326 are applied to multipliers 1328. The rest of the components and processing of the BCC synthesizer of FIG. 13 are analogous to those of the BCC synthesizer of FIG. 7. When the LR filters are implemented in the frequency domain, such as LR filters 1320 of FIG. 13, the possibility exists to use different filter lengths for different frequency sub-bands, for example, shorter filters at higher frequencies. This can be used to reduce overall computational complexity. Hybrid Embodiments Even when the LR processors are implemented in the frequency domain, as in FIG. 13, the computational complexity of the BCC synthesizer may still be relatively high. For example, if late reverberation is modeled with an impulse response, the impulse response should be relatively long in order to obtain high-quality diffuse sound. On the other hand, the coherence-based audio synthesis of the '437 application is typically less computationally complex and provides good performance for high frequencies. This leads to the possibility of implementing a hybrid audio processing system that applies the reverberation-based processing of the present invention to low frequencies (e.g., frequencies below about 1-3 kHz), while the coherence-based processing of the '437 application is applied to high frequencies (e.g., frequencies above about 1-3 kHz), thereby achieving a system that provides good performance over the entire frequency range while reducing overall computational complexity. Alternative Embodiments Although the present invention has been described in the context of reverberation-based BCC processing that also relies on ICTD and ICLD data, the invention is not so limited. In theory, the BCC processing of present invention can be implemented without ICTD and/or ICLD data, with or without other suitable cue codes, such as, for example, those associated with head-related transfer functions. As mentioned earlier, the present invention can be implemented in the context of BCC coding in which more than one “combined” channel is generated. For example, BCC coding could be applied to the six input channels of 5.1 surround sound to generate two combined channels: one based on the left and rear left channels and one based on the right and rear right channels. In one possible implementation, each of the combined channels could also be based on the two other 5.1 channels (i.e., the center channel and the LFE channel). In other words, a first combined channel could be based on the sum of the left, rear left, center, and LFE channels, while the second combined channel could be based on the sum of the right, rear right, center, and LFE channels. In this case, there could be two different sets of BCC cue codes: one for the channels used to generate the first combined channel and one for the channels used to generate the second combined channel, with a BCC decoder selectively applying those cue codes to the two combined channels to generate synthesized 5.1 surround sound at the receiver. Advantageously, this scheme would enable the two combined channels to be played back as conventional left and right channels on conventional stereo receivers. Note that, in theory, when there are multiple “combined” channels, one or more of the combined channels may in fact be based on individual input channels. For example, BCC coding could be applied to 7.1 surround sound to generate a 5.1 surround signal and appropriate BCC codes, where, for example, the LFE channel in the 5.1 signal could simply be a replication of the LFE channel in the 7.1 signal. The present invention has been described in the context of audio synthesis techniques in which two or more output channels are synthesized from one or more combined channels, where there is one LR filter for each different output channel. In alternative embodiments, it is possible to synthesize C output channels using fewer than C LR filters. This can be achieved by combining the diffuse channel outputs of the fewer-than-C LR filters with the one or more combined channels to generate C synthesized output channels. For example, one or more of the output channels might get generated without any reverberation, or one LR filter could be used to generate two or more output channels by combining the resulting diffuse channel with different scaled, delayed version of the one or more combined channels. Alternatively, this can be achieved by applying the reverberation techniques described earlier for certain output channels, while applying other coherence-based synthesis techniques for other output channels. Other coherence-based synthesis techniques that may be suitable for such hybrid implementations are described in E. Schuijers, W. Oomen, B. den Brinker, and J. Breebaart, “Advances in parametric coding for high-quality audio,” Preprint 114th Convention Aud. Eng. Soc., March 2003, and Audio Subgroup, Parametric coding for High Quality Audio, ISO/IEC JTC1/SC29/WG11 MPEG2002/N5381, December 2002, the teachings of both of which are incorporated herein by reference. Although the interface between BCC encoder 302 and BCC decoder 304 in FIG. 3 has been described in the context of a transmission channel, those skilled in the art will understand that, in addition or in the alternative, that interface may include a storage medium. Depending on the particular implementation, the transmission channels may be wired or wire-less and can use customized or standardized protocols (e.g., IP). Media like CD, DVD, digital tape recorders, and solid-state memories can be used for storage. In addition, transmission and/or storage may, but need not, include channel coding. Similarly, although the present invention has been described in the context of digital audio systems, those skilled in the art will understand that the present invention can also be implemented in the context of analog audio systems, such as AM radio, FM radio, and the audio portion of analog television broadcasting, each of which supports the inclusion of an additional in-band low-bitrate transmission channel. The present invention can be implemented for many different applications, such as music reproduction, broadcasting, and telephony. For example, the present invention can be implemented for digital radio/TV/internet (e.g., Webcast) broadcasting such as Sirius Satellite Radio or XM. Other applications include voice over IP, PSTN or other voice networks, analog radio broadcasting, and Internet radio. Depending on the particular application, different techniques can be employed to embed the sets of BCC parameters into the mono audio signal to achieve a BCC signal of the present invention. The availability of any particular technique may depend, at least in part, on the particular transmission/storage medium(s) used for the BCC signal. For example, the protocols for digital radio broadcasting usually support inclusion of additional “enhancement” bits (e.g., in the header portion of data packets) that are ignored by conventional receivers. These additional bits can be used to represent the sets of auditory scene parameters to provide a BCC signal. In general, the present invention can be implemented using any suitable technique for watermarking of audio signals in which data corresponding to the sets of auditory scene parameters are embedded into the audio signal to form a BCC signal. For example, these techniques can involve data hiding under perceptual masking curves or data hiding in pseudo-random noise. The pseudo-random noise can be perceived as “comfort noise.” Data embedding can also be implemented using methods similar to “bit robbing” used in TDM (time division multiplexing) transmission for in-band signaling. Another possible technique is mu-law LSB bit flipping, where the least significant bits are used to transmit data. BCC encoders of the present invention can be used to convert the left and right audio channels of a binaural signal into an encoded mono signal and a corresponding stream of BCC parameters. Similarly, BCC decoders of the present invention can be used to generate the left and right audio channels of a synthesized binaural signal based on the encoded mono signal and the corresponding stream of BCC parameters. The present invention, however, is not so limited. In general, BCC encoders of the present invention may be implemented in the context of converting M input audio channels into N combined audio channels and one or more corresponding sets of BCC parameters, where M>N. Similarly, BCC decoders of the present invention may be implemented in the context of generating P output audio channels from the N combined audio channels and the corresponding sets of BCC parameters, where P>N, and P may be the same as or different from M. Although the present invention has been described in the context of transmission/storage of a single combined (e.g., mono) audio signal with embedded auditory scene parameters, the present invention can also be implemented for other numbers of channels. For example, the present invention may be used to transmit a two-channel audio signal with embedded auditory scene parameters, which audio signal can be played back with a conventional two-channel stereo receiver. In this case, a BCC decoder can extract and use the auditory scene parameters to synthesize a surround sound (e.g., based on the 5.1 format). In general, the present invention can be used to generate M audio channels from N audio channels with embedded auditory scene parameters, where M>N. Although the present invention has been described in the context of BCC decoders that apply the techniques of the '877 and '458 applications to synthesize auditory scenes, the present invention can also be implemented in the context of BCC decoders that apply other techniques for synthesizing auditory scenes that do not necessarily rely on the techniques of the '877 and '458 applications. The present invention may be implemented as circuit-based processes, including possible implementation on a single integrated circuit. As would be apparent to one skilled in the art, various functions of circuit elements may also be implemented as processing steps in a software program. Such software may be employed in, for example, a digital signal processor, micro-controller, or general-purpose computer. The present invention can be embodied in the form of methods and apparatuses for practicing those methods. The present invention can also be embodied in the form of program code embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The present invention can also be embodied in the form of program code, for example, whether stored in a storage medium, loaded into and/or executed by a machine, or transmitted over some transmission medium or carrier, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code segments combine with the processor to provide a unique device that operates analogously to specific logic circuits. It will be further understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of this invention may be made by those skilled in the art without departing from the scope of the invention as expressed in the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention relates to the encoding of audio signals and the subsequent synthesis of auditory scenes from the encoded audio data. 2. Description of the Related Art When a person hears an audio signal (i.e., sounds) generated by a particular audio source, the audio signal will typically arrive at the person's left and right ears at two different times and with two different audio (e.g., decibel) levels, where those different times and levels are functions of the differences in the paths through which the audio signal travels to reach the left and right ears, respectively. The person's brain interprets these differences in time and level to give the person the perception that the received audio signal is being generated by an audio source located at a particular position (e.g., direction and distance) relative to the person. An auditory scene is the net effect of a person simultaneously hearing audio signals generated by one or more different audio sources located at one or more different positions relative to the person. The existence of this processing by the brain can be used to synthesize auditory scenes, where audio signals from one or more different audio sources are purposefully modified to generate left and right audio signals that give the perception that the different audio sources are located at different positions relative to the listener. FIG. 1 shows a high-level block diagram of conventional binaural signal synthesizer 100 , which converts a single audio source signal (e.g., a mono signal) into the left and right audio signals of a binaural signal, where a binaural signal is defined to be the two signals received at the eardrums of a listener. In addition to the audio source signal, synthesizer 100 receives a set of spatial cues corresponding to the desired position of the audio source relative to the listener. In typical implementations, the set of spatial cues comprises an inter-channel level difference (ICLD) value (which identifies the difference in audio level between the left and right audio signals as received at the left and right ears, respectively) and an inter-channel time difference (ICTD) value (which identifies the difference in time of arrival between the left and right audio signals as received at the left and right ears, respectively). In addition or as an alternative, some synthesis techniques involve the modeling of a direction-dependent transfer function for sound from the signal source to the eardrums, also referred to as the head-related transfer function (HRTF). See, e.g., J. Blauert, The Psychophysics of Human Sound Localization, MIT Press, 1983, the teachings of which are incorporated herein by reference. Using binaural signal synthesizer 100 of FIG. 1 , the mono audio signal generated by a single sound source can be processed such that, when listened to over headphones, the sound source is spatially placed by applying an appropriate set of spatial cues (e.g., ICLD, ICTD, and/or HRTF) to generate the audio signal for each ear. See, e.g., D. R. Begault, 3- D Sound for Virtual Reality and Multimedia, Academic Press, Cambridge, Mass., 1994. Binaural signal synthesizer 100 of FIG. 1 generates the simplest type of auditory scenes: those having a single audio source positioned relative to the listener. More complex auditory scenes comprising two or more audio sources located at different positions relative to the listener can be generated using an auditory scene synthesizer that is essentially implemented using multiple instances of binaural signal synthesizer, where each binaural signal synthesizer instance generates the binaural signal corresponding to a different audio source. Since each different audio source has a different location relative to the listener, a different set of spatial cues is used to generate the binaural audio signal for each different audio source. FIG. 2 shows a high-level block diagram of conventional auditory scene synthesizer 200 , which converts a plurality of audio source signals (e.g., a plurality of mono signals) into the left and right audio signals of a single combined binaural signal, using a different set of spatial cues for each different audio source. The left audio signals are then combined (e.g., by simple addition) to generate the left audio signal for the resulting auditory scene, and similarly for the right. One of the applications for auditory scene synthesis is in conferencing. Assume, for example, a desktop conference with multiple participants, each of whom is sitting in front of his or her own personal computer (PC) in a different city. In addition to a PC monitor, each participant's PC is equipped with (1) a microphone that generates a mono audio source signal corresponding to that participant's contribution to the audio portion of the conference and (2) a set of headphones for playing that audio portion. Displayed on each participant's PC monitor is the image of a conference table as viewed from the perspective of a person sitting at one end of the table. Displayed at different locations around the table are real-time video images of the other conference participants. In a conventional mono conferencing system, a server combines the mono signals from all of the participants into a single combined mono signal that is transmitted back to each participant. In order to make more realistic the perception for each participant that he or she is sitting around an actual conference table in a room with the other participants, the server can implement an auditory scene synthesizer, such as synthesizer 200 of FIG. 2 , that applies an appropriate set of spatial cues to the mono audio signal from each different participant and then combines the different left and right audio signals to generate left and right audio signals of a single combined binaural signal for the auditory scene. The left and right audio signals for this combined binaural signal are then transmitted to each participant. One of the problems with such conventional stereo conferencing systems relates to transmission bandwidth, since the server has to transmit a left audio signal and a right audio signal to each conference participant. | <SOH> SUMMARY OF THE INVENTION <EOH>The '877 and '458 applications describe techniques for synthesizing auditory scenes that address the transmission bandwidth problem of the prior art. According to the '877 application, an auditory scene corresponding to multiple audio sources located at different positions relative to the listener is synthesized from a single combined (e.g., mono) audio signal using two or more different sets of auditory scene parameters (e.g., spatial cues such as an inter-channel level difference (ICLD) value, an inter-channel time delay (ICTD) value, and/or a head-related transfer function (HRTF)). As such, in the case of the PC-based conference described previously, a solution can be implemented in which each participant's PC receives only a single mono audio signal corresponding to a combination of the mono audio source signals from all of the participants (plus the different sets of auditory scene parameters). The technique described in the '877 application is based on an assumption that, for those frequency sub-bands in which the energy of the source signal from a particular audio source dominates the energies of all other source signals in the mono audio signal, from the perspective of the perception by the listener, the mono audio signal can be treated as if it corresponded solely to that particular audio source. According to implementations of this technique, the different sets of auditory scene parameters (each corresponding to a particular audio source) are applied to different frequency sub-bands in the mono audio signal to synthesize an auditory scene. The technique described in the '877 application generates an auditory scene from a mono audio signal and two or more different sets of auditory scene parameters. The '877 application describes how the mono audio signal and its corresponding sets of auditory scene parameters are generated. The technique for generating the mono audio signal and its corresponding sets of auditory scene parameters is referred to in this specification as binaural cue coding (BCC). The BCC technique is the same as the perceptual coding of spatial cues (PCSC) technique referred to in the '877 and '458 applications. According to the '458 application, the BCC technique is applied to generate a combined (e.g., mono) audio signal in which the different sets of auditory scene parameters are embedded in the combined audio signal in such a way that the resulting BCC signal can be processed by either a BCC-based decoder or a conventional (i.e., legacy or non-BCC) receiver. When processed by a BCC-based decoder, the BCC-based decoder extracts the embedded auditory scene parameters and applies the auditory scene synthesis technique of the '877 application to generate a binaural (or higher) signal. The auditory scene parameters are embedded in the BCC signal in such a way as to be transparent to a conventional receiver, which processes the BCC signal as if it were a conventional (e.g., mono) audio signal. In this way, the technique described in the '458 application supports the BCC processing of the '877 application by BCC-based decoders, while providing backwards compatibility to enable BCC signals to be processed by conventional receivers in a conventional manner. The BCC techniques described in the '877 and '458 applications effectively reduce transmission bandwidth requirements by converting, at a BCC encoder, a binaural input signal (e.g., left and right audio channels) into a single mono audio channel and a stream of binaural cue coding (BCC) parameters transmitted (either in-band or out-of-band) in parallel with the mono signal. For example, a mono signal can be transmitted with approximately 50-80% of the bit rate otherwise needed for a corresponding two-channel stereo signal. The additional bit rate for the BCC parameters is only a few kbits/sec (i.e., more than an order of magnitude less than an encoded audio channel). At the BCC decoder, left and right channels of a binaural signal are synthesized from the received mono signal and BCC parameters. The coherence of a binaural signal is related to the perceived width of the audio source. The wider the audio source, the lower the coherence between the left and right channels of the resulting binaural signal. For example, the coherence of the binaural signal corresponding to an orchestra spread out over an auditorium stage is typically lower than the coherence of the binaural signal corresponding to a single violin playing solo. In general, an audio signal with lower coherence is usually perceived as more spread out in auditory space. The BCC techniques of the '877 and '458 applications generate binaural signals in which the coherence between the left and right channels approaches the maximum possible value of 1. If the original binaural input signal has less than the maximum coherence, the BCC decoder will not recreate a stereo signal with the same coherence. This results in auditory image errors, mostly by generating too narrow images, which produces a too “dry” acoustic impression. In particular, the left and right output channels will have a high coherence, since they are generated from the same mono signal by slowly-varying level modifications in auditory critical bands. A critical band model, which divides the auditory range into a discrete number of audio sub-bands, is used in psychoacoustics to explain the spectral integration of the auditory system. For headphone playback, the left and right output channels are the left and right ear input signals, respectively. If the ear signals have a high coherence, then the auditory objects contained in the signals will be perceived as very “localized” and they will have only a very small spread in the auditory spatial image. For loudspeaker playback, the loudspeaker signals only indirectly determine the ear signals, since cross-talk from the left loudspeaker to the right ear and from the right loudspeaker to the left ear has to be taken into account. Moreover, room reflections can also play a significant role for the perceived auditory image. However, for loudspeaker playback, the auditory image of highly coherent signals is very narrow and localized, similar to headphone playback. According to the '437 application, the BCC techniques of the '877 and '458 applications are extended to include BCC parameters that are based on the coherence of the input audio signals. The coherence parameters are transmitted from the BCC encoder to a BCC decoder along with the other BCC parameters in parallel with the encoded mono audio signal. The BCC decoder applies the coherence parameters in combination with the other BCC parameters to synthesize an auditory scene (e.g., the left and right channels of a binaural signal) with auditory objects whose perceived widths more accurately match the widths of the auditory objects that generated the original audio signals input to the BCC encoder. A problem related to the narrow image width of auditory objects generated by the BCC techniques of the '877 and '458 applications is the sensitivity to inaccurate estimates of the auditory spatial cues (i.e., the BCC parameters). Especially with headphone playback, auditory objects that should be at a stable position in space tend to move randomly. The perception of objects that unintentionally move around can be annoying and substantially degrade the perceived audio quality. This problem substantially if not completely disappears, when embodiments of the '437 application are applied. The coherence-based technique of the '437 application tends to work better at relatively high frequencies than at relatively low frequencies. According to certain embodiments of the present invention, the coherence-based technique of the '437 application is replaced by a reverberation technique for one or more—and possibly all—frequency sub-bands. In one hybrid embodiment, the reverberation technique is implemented for low frequencies (e.g., frequency sub-bands less than a specified (e.g., empirically determined) threshold frequency), while the coherence-based technique of the '437 application is implemented for high frequencies (e.g., frequency sub-bands greater than the threshold frequency). In one embodiment, the present invention is a method for synthesizing an auditory scene. At least one input channel is processed to generate two or more processed input signals, and the at least one input channel is filtered to generate two or more diffuse signals. The two or more diffuse signals are combined with the two or more processed input signals to generate a plurality of output channels for the auditory scene. In another embodiment, the present invention is an apparatus for synthesizing an auditory scene. The apparatus includes a configuration of at least one time domain to frequency domain (TD-FD) converter and a plurality of filters, where the configuration is adapted to generate two or more processed FD input signals and two or more diffuse FD signals from at least one TD input channel. The apparatus also has (a) two or more combiners adapted to combine the two or more diffuse FD signals with the two or more processed FD input signals to generate a plurality of synthesized FD signals and (b) two or more frequency domain to time domain (FD-TD) converters adapted to convert the synthesized FD signals into a plurality of TD output channels for the auditory scene. | 20040401 | 20090901 | 20050818 | 58080.0 | 2 | FAULK, DEVONA E | LATE REVERBERATION-BASED SYNTHESIS OF AUDITORY SCENES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,761 | ACCEPTED | Shredder with lock for on/off switch | The present application discloses a shredder with a switch lock that locks the on/off switch in its on/off position. | 1. A shredder comprising: a shredder mechanism including an electrically powered motor and cutter elements, the shredder mechanism enabling articles to be shredded to be fed into the cutter elements and the motor being operable to drive the cutter elements so that the cutter elements shred the articles fed therein; an on/off switch electrically coupled to the motor of the shredder mechanism, the switch including a manually engageable portion manually movable by a user's hand between at least (a) an on position wherein the switch enables delivery of electric power to the motor and (b) an off position disabling the delivery of electric power to the motor; a switch lock movable between (a) a locking position wherein the switch is locked in the off position and (b) a releasing position wherein the switch is released for movement from the off position. 2. A shredder according to claim 1, wherein the switch lock includes a manually engageable portion manually movable by the user's hand to move the switch lock between the locking and releasing positions. 3. A shredder according to claim 2, wherein the switch lock is constructed such that, when the on/off switch is in the on position thereof, moving the switch lock from the releasing position to the locking position causes the switch to move into the off position. 4. A shredder according to claim 3, wherein the switch lock includes a camming surface configured to cam the switch from the on position to the off position as the switch lock moves from the releasing position to the locking position. 5. A shredder according to claim 1, further comprising a housing in which the shredder mechanism is received, the housing including an opening for enabling the articles to be shredded to be fed into the housing and into the cutter elements. 6. A shredder according to claim 5, further comprising a cover associated with opening of the housing, the cover being movable between (a) a closed position covering the opening for preventing the articles to be shredded from being fed into the housing and into the cutter elements, and (b) an open position uncovering the opening for allowing the articles to be shredded to be fed into the housing and into the cutter elements. 7. A shredder according to claim 6, wherein the cover is linked with the switch lock such that the cover and the switch lock move together between (a) the open position of the cover and the releasing position of the switch lock and (b) the closed position of the cover and the locking position of the switch lock. 8. A shredder according to claim 7, wherein the cover is manually movable between the open and closed positions thereof, thereby enabling manual movement of the cover between the open and closed positions to move the switch lock between the releasing and locking positions thereof, respectively. 9. A shredder according to claim 8, wherein the switch lock is constructed such that, when the on/off switch is in the on position thereof, moving the switch lock from the releasing position to the locking position causes the switch to move into the off position. 10. A shredder according to claim 9, wherein the switch lock includes a camming surface configured to cam the switch from the on position to the off position as the switch lock moves from the releasing position to the locking position. 11. A shredder according to claim 3, wherein the switch is also movable to reverse position enabling delivery of electric power to the motor so as to operate the motor to drive the cutter elements in a reverse manner, the on position and the reverse position being on opposing sides of the off position, wherein the switch lock is also constructed such that, when the on/off switch is in the reverse position, moving the switch lock from the releasing position to the locking position causes the switch to move into the off position. 12. A shredder according to claim 11, wherein the switch lock includes a pair of camming surfaces, one of the camming surfaces being configured to cam the switch from the on position to the off position as the switch lock moves from the releasing position to the locking position, the other of the camming surfaces being configured to cam the switch from the reverse position to the off position as the switch lock moves from the releasing position to the locking position. 13. A shredder according to claim 9, wherein the switch is also movable to reverse position enabling delivery of electric power to the motor so as to operate the motor to drive the cutter elements in a reverse manner, the on position and the reverse position being on opposing sides of the off position, wherein the switch lock is also constructed such that, when the on/off switch is in the reverse position, moving the switch lock from the releasing position to the locking position causes the switch to move into the off position. 14. A shredder according to claim 13, wherein the switch lock includes a pair of camming surfaces, one of the camming surfaces being configured to cam the switch from the on position to the off position as the switch lock moves from the releasing position to the locking position, the other of the camming surfaces being configured to cam the switch from the reverse position to the off position as the switch lock moves from the releasing position to the locking position. 15. A shredder according to claim 1, comprising a status indicator for visually indicating whether the switch lock is in the locking position. | FIELD OF THE INVENTION The present invention relates to shredders for destroying articles, such as documents, CDs, floppy disks, etc. BACKGROUND OF THE INVENTION Shredders are well known devices used for shredding items, such as documents, CDs, floppy disks, etc. With identity theft, there has been an increased consumer awareness of the desirability of shredding documents containing sensitive personal information, such as credit card bills, tax documents bearing a person's Social Security number etc. Shredders contain a series of cutting elements for shredding articles fed therein. Generally, it is desirable to prevent the inadvertent actuation of the motor driving the cutter elements. To this end, the present invention endeavors to provide a construction that has a reduced chance of being inadvertently actuated. SUMMARY OF THE INVENTION One aspect of the present invention provides a shredder with a switch lock that locks the on/off switch in its off position. Specifically, the shredder comprises a shredder mechanism including an electrically powered motor and cutter elements. The shredder mechanism enables articles to be shredded to be fed into the cutter elements. The motor is operable to drive the cutter elements so that the cutter elements shred the articles therein. The on/off switch is electrically coupled to the motor of the shredder mechanism. The switch includes a manually engageable portion manually movable by a user's hand between at least (a) an on position wherein the switch enables delivery of electric power to the motor, and (b) an off position disabling the delivery of electric power to the motor. The switch lock is movable between (a) a locking position wherein the switch is locked in the off position, and (b) a releasing position wherein the switch is released for movement from the off position. Other objects, features, and advantages will become appreciated from the following detailed description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a shredder seated atop a container with a switch lock thereof in a locking position; FIG. 1A is a perspective exploded view of the shredder of FIG. 1; FIG. 2 is a perspective view of the shredder of Figure without the container and with the switch lock in the releasing position thereof; FIG. 3 is a top plan view of the shredder of FIG. 1 without the container and with the switch lock in the locking position; FIG. 4A is a top plan view showing the switch lock, an on/off switch of the shredder in isolation from the remainder of the shredder with the switch lock in the locking position; FIG. 4B is a view similar to FIG. 4A, but with the switch lock in the releasing position; FIG. 5 is a bottom perspective view of the shredder of FIG. 1 with the shredder unit mechanism removed and the switch lock in the releasing position; FIG. 6 is a view similar to FIG. 5 with the switch lock in the locking position; FIG. 7 is a perspective view of an alternative embodiment of a shredder with the container omitted, wherein the switch lock and throat cover move together, with the switch lock in the releasing position and the throat cover in the open position; FIG. 8 is a perspective view similar to FIG. 7, but with the switch lock in the locking position and the throat cover in the closed position; FIG. 9 is a top plan view of the shredder of FIG. 7 with the switch lock in the releasing position and the throat cover in the open position; FIG. 10 is a top plan view similar to FIG. 9, but with the switch lock in the locking position and the throat cover in the closed position; FIG. 11A is a vertical cross-section taken through the front to back centerline of the shredder of FIG. 7 with the shredder mechanism removed and with the switch lock in the locking position and the throat cover in the closed position; FIG. 11B is a view similar to FIG. 11A, but with the switch lock in the releasing position and the throat cover in the open position; FIG. 12A is a top plan view showing the switch lock, the on/off switch of the shredder, a switch lock indicator and an indicator window of the shredder housing in isolation from the remainder of the shredder with the switch lock in the locking position; FIG. 12B is a view similar to FIG. 12A, but with the switch lock in the releasing position; and FIG. 13 is a perspective view of a shaft with a plurality of cutter elements. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT(S) OF THE INVENTION FIGS. 1-6 illustrate an embodiment of a shredder constructed in accordance with one embodiment of the present invention. The shredder is generally indicated at 10. The shredder 10 sits atop a waste container, generally indicated at 12. The shredder 10 illustrated is designed specifically for use with the container 12, as the shredder housing 14 sits on the upper periphery of the waste container 12 is a nested relation. However, the shredder 10 may be of the type provided with an adaptable mount for attachment to a wide variety of containers. Generally speaking, the shredder 10 may have any suitable construction or configuration and the illustrated embodiment is not intended to be limiting in any way. The shredder 10 includes a shredder mechanism 16 including an electrically powered motor 18 and a plurality of cutter elements 20. The cutter elements 20 are mounted on a pair of parallel rotating shafts 22 in any suitable manner, and an example of a shaft 22 with cutter elements 20 is illustrated in FIG. 13. The motor 18 operates using electrical power to rotatably drive the shafts 22 and the cutter elements 20 through a conventional transmission 23 so that the cutter elements 20 shred articles fed therein. The shredder mechanism 16 also may include a sub-frame 21 for mounting the shafts 22, the motor 18, and the transmission 23. The operation and construction of such a shredder mechanism 16 are well known and need not be described herein in detail. Generally, any suitable shredder mechanism 16 known in the art or developed hereafter may be used. The shredder 10 also includes the shredder housing 14, mentioned above. The shredder housing 14 includes top wall 24 that sits atop the container 12. The top wall 14 is molded from plastic and has an opening 26 near the front thereof, which is formed in part by a downwardly depending generally U-shaped member 28. The opening 26 allows waste to be discarded into the container 12 without being passed through the shredder mechanism 16, and the member 28 may act as a handle for carrying the shredder 10 separate from the container 12. As an optional feature, this opening 26 may be provided with a lid, such as a pivoting lid, that opens and closes the opening 26. However, this opening in general is optional and may be omitted entirely. Moreover, the shredder housing 14 and its top wall 24 may have any suitable construction or configuration. The shredder housing 14 also includes a bottom receptacle 30 having a bottom wall, four side walls, and an open top. The shredder mechanism 16 is received therein, and the receptacle 30 is affixed to the underside of the top wall 24 by fasteners 32 inserted through bores in posts 34 on the receptacle 30 and engaged with corresponding bores in posts 35 (see FIGS. 5 and 6). The receptacle 30 has a downwardly facing opening 31 for permitting shredded articles to be discharged from the shredder mechanism 16 into the container 12. The top wall 24 has a generally laterally extending opening 36 extending generally parallel and above the cutter elements 20. The opening 36, often referred to as a throat, enables the articles being shredded to be fed into the cutter elements 20. As can be appreciated, the opening 36 is relatively narrow, which is desirable for preventing overly thick items, such as large stacks of documents, from being fed into cutter elements 20, which could lead to jamming. The opening 36 may have any configuration. The top wall 24 also has a switch recess 38 with an opening 40 therethrough. An on/off switch 42 includes a switch module 44 (FIGS. 4A-6) mounted to the top wall 24 underneath the recess 38 by fasteners 45, and a manually engageable portion 46 that moves laterally within the recess 38. The switch module 44 has a movable element 48 that connects to the manually engageable portion 46 through the opening 40. This enables movement of the manually engageable portion 46 to move the switch module between its states. In the illustrated embodiment, the switch module 44 connects the motor 18 to the power supply (not shown). Typically, the power supply will be a standard power cord 47 with a plug 49 on its end that plugs into a standard AC outlet, but any suitable manner of power delivery may be used. The switch 42 is movable between an on position and an off position by moving the portion 46 laterally within the recess 38. In the on position, contacts in the switch module 44 are closed by movement of the manually engageable portion 46 and the movable element 48 to enable a delivery of electrical power to the motor 18. In the off position, contacts in the switch module 44 are opened to disable the delivery of electric power to the motor 18. As an option, the switch 42 may also have a reverse position wherein contacts are closed to enable delivery of electrical power to operate the motor 18 in a reverse manner. This would be done by using a reversible motor and applying a current that is of a reverse polarity relative to the on position. The capability to operate the motor 18 in a reversing manner is desirable to move the cutter elements 20 in a reversing direction for clearing jams. In the illustrated embodiment, in the off position the manually engageable portion 46 and the movable element 48 would be located generally in the center of the recess 38, and the on and reverse positions would be on opposing lateral sides of the off position. Generally, the construction and operation of the switch 42 for controlling the motor 42 are well known and any construction for such a switch 42 may be used. The top cover 24 also includes another recess 50 associated with a switch lock 52. The switch lock 52 includes a manually engageable portion 54 that is movable by a user's hand and a locking portion 56 (FIGS. 4A-6). The manually engageable portion 54 is seated in the recess 50 and the locking portion 56 is located beneath the top wall 24. The locking portion 56 is illustrated as being integrally formed as a plastic piece with the manually engageable portion 54 and extends beneath the top wall 24 via an opening 58 formed in the recess 50. The recess 50 also has a pair of slots 60 on the opposing lateral sides thereof. The manually engageable portion 54 has resilient catch members 62 with flared ends that are inserted into these slots 60 so as to securely mount the switch lock 52 for sliding movement within the recess 50. The switch module 44 is mounted so as to define a small space between it and the underside of the top wall 24. The movable element 48 of the switch 42 extends through this space. The locking portion 56 of the switch lock 52 has a switch receiving recess 64 with a pair of angled camming surfaces 66, 68 on opposing sides thereof. This construction causes the switch 42 to move from either its on position or reverse position to its off position as the switch lock 52 is moved from a releasing position to a locking position. In the releasing position, the locking portion 56 is disengaged from the movable element 48 of the switch 42, thus enabling the switch 42 to be moved between its on, off, and reverse positions. In the locking position, the switch lock 52 extends into the space between the module 44 and the top wall 24 so that the movable element 48 is received in its off position in the recess 64 and restrained against movement to either its on or reverse position. The camming surfaces 66, 68 are provided to move the switch 42 to its off position as the switch lock 52 is moved from its releasing position to its locking position. Specifically, when the switch 42 is in the on position, cam surface 66 will engage the movable element 48 of the switch 42 and cam the same so as to move the switch 42 into the off position with the movable element 48 thereafter restrained against movement from its off position. Likewise, when the switch 42 is in the reverse position, cam surface 68 will engage the movable element 48 and cam the same so as to move the switch 42 to the off position with the movable element 48 thereafter restrained from movement from its off position. FIGS. 4A-6 best illustrate these features of this embodiment of the invention. In embodiments where the switch 42 has no reverse position, the corresponding cam surface 68 may be omitted. Also, the switch lock 52 may be constructed to move the switch 42 from the on and/or reverse position to the off position as the switch lock 52 moves from the releasing position to the locking position by any suitable arrangement, and the cam surface(s) are not intended to be limiting. For example, mechanical links or other structures may be used. Moreover, it is not necessary to have the switch lock 52 move the switch 42 into its off position. Instead, the switch lock 52 could be constructed so that the switch 42 is manually moved to its off position prior to moving the switch lock 52 to its locking position. Preferably, but not necessarily, the manually engageable portion 54 of the switch lock 52 has an upwardly extending projection 70 for facilitating movement of the switch lock 56 between the locking and releasing positions. One advantage of the switch lock 52 is that, by holding the switch 42 in the off position, to activate the shredder mechanism 16 the switch lock 52 must first be moved to its releasing position, and then the switch 42 is moved to its on or reverse position. This reduces the likelihood of the shredder mechanism 16 being activated unintentionally. FIGS. 7-11B illustrate another embodiment of a shredder 100. This shredder 100 shares many common features with the shredder 10 of the first embodiment, and those common features are marked with the same reference numerals. The primary difference between shredder 10 and shredder 100 is the cover 102. The cover 102 is seated within a recess 103 formed in the top wall 24 and can move between open and closed positions. In the closed position, the cover 102 covers the opening 36 to prevent articles from being fed into the housing 14 and into the cutter elements 20. In the open position, the cover 102 uncovers the opening 36 to allow the articles to be shredded to be fed into the housing 14 and into the cutter elements 20. Specifically, the cover 102 has an opening 104 shaped similarly to opening 36. In the open position, these openings 36, 104 are aligned to enable feeding of articles through the openings 36, 104 and into the cutter elements 20. In the closed position, these openings 36, 104 are out of alignment, thus preventing such feeding of articles into the cutter elements 20. In this embodiment, switch lock 52 is integrated as a molded part with the cover 102. Basically, the manually engageable portion 54 illustrated in the previous embodiment is eliminated and the locking portion 56 is formed integrally with the cover 102 (see FIGS. 11A and 11B). As a result, the cover 102 and the switch lock (i.e., locking portion 56) move together between (a) the open position of the cover 102 and the releasing position of the switch lock 52, and (b) the closed position of the cover 102 and the locking position of the switch lock 52. As a result of this construction, if the switch 42 is left in the on or reverse position, the user can simply move the cover 102 to its closed position to simultaneously close the opening 36 and move the switch 42 to its off position by the camming action of locking portion 56 moving to its locking position. Of course, if the locking portion 56 is of the type where it does not move the switch 42 to its off position as during movement to the locking position, then the user would first move the switch 42 to its off position. In either case, to use the shredder, the user first moves the cover 102 to its open position, which simultaneously moves the locking portion 56 to its releasing position. Then, the switch 42 can be moved to the on position (or the reverse position if needed). The switch lock 52 and the cover 102 need not be linked by being integrally formed together as one piece, and they could be formed separately and linked together for movement in any suitable way. Also, the cover 102 could be independent from the switch lock 52, with the same type of switch lock being used as is used in the first embodiment. The cover 102 also has an upwardly extending ridge 114 for facilitating movement of the cover 102 and the switch lock 52. In the second embodiment illustrated, the top wall 24 also has an indicator window 106. The window 106 may simply be an opening 106, or it may have a transparent/translucent member therein. An arm 108 is formed integrally with the locking portion 56 and extends therefrom. The end of the arm 108 carries a locked indicator 110 and an unlocked indicator 112. The locked indicator 110 has the appearance of a locked padlock, and the unlocked indicator 110 has the appearance of an unlocked padlock. When the cover 102 is in the closed position and the switch lock 52 provided by locking portion 56 is in the locking position, the locked indicator 110 is located beneath the indicator window 106, enabling the user to visually see the locked indicator 100 and tell that the on/off switch 42 is locked in the off position (FIG. 12A). Likewise, when the cover 102 is in the open position and the switch lock 52 is in the releasing position, the unlocked indicator 112 is positioned beneath the window 106, enabling the user to visually see the unlocked indicator 112 and tell that the on/off switch 42 is freely movable (FIG. 12B). Generally, this construction may be considered as providing a status indicator that visually indicates to the user whether the switch lock 52 is in the locking position. As one variation, the unlocked indicator 112 could be eliminated, providing only the locked indicator 110 to indicate that the switch lock 52 is in its locked position, with the locked indicator's absence in the window 106 indicating that switch lock 52 is in its releasing position. As another variation, one or more LEDs or other type of light may be used to indicate whether the switch lock 52 is in the locking position. Any other suitable device may be used to indicate the status of the switch lock and the examples herein should not be considered limiting. The foregoing embodiments have been provided solely for the purposes of illustrating the structural and functional principles of the present invention, and should not be considered limiting. To the contrary, the present invention is intended to encompass all variations, modifications, and alterations within the spirit and scope of the appended claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>Shredders are well known devices used for shredding items, such as documents, CDs, floppy disks, etc. With identity theft, there has been an increased consumer awareness of the desirability of shredding documents containing sensitive personal information, such as credit card bills, tax documents bearing a person's Social Security number etc. Shredders contain a series of cutting elements for shredding articles fed therein. Generally, it is desirable to prevent the inadvertent actuation of the motor driving the cutter elements. To this end, the present invention endeavors to provide a construction that has a reduced chance of being inadvertently actuated. | <SOH> SUMMARY OF THE INVENTION <EOH>One aspect of the present invention provides a shredder with a switch lock that locks the on/off switch in its off position. Specifically, the shredder comprises a shredder mechanism including an electrically powered motor and cutter elements. The shredder mechanism enables articles to be shredded to be fed into the cutter elements. The motor is operable to drive the cutter elements so that the cutter elements shred the articles therein. The on/off switch is electrically coupled to the motor of the shredder mechanism. The switch includes a manually engageable portion manually movable by a user's hand between at least (a) an on position wherein the switch enables delivery of electric power to the motor, and (b) an off position disabling the delivery of electric power to the motor. The switch lock is movable between (a) a locking position wherein the switch is locked in the off position, and (b) a releasing position wherein the switch is released for movement from the off position. Other objects, features, and advantages will become appreciated from the following detailed description, the accompanying drawings, and the appended claims. | 20040402 | 20060509 | 20051006 | 75483.0 | 4 | ROSENBAUM, MARK | SHREDDER WITH LOCK FOR ON/OFF SWITCH | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,815 | ACCEPTED | Power plug with overloaded display | The present invention relates to providing a power plug with overloaded display, which provides users with the function of warning display for protecting the power plug from over-heated melting and from shorting and catching on fire. The character is that an embedded positioned block is arranged on the periphery of the electric metal-pin of said power plug, and a thermochromic film is coated on the surface of said embedded positioned block, and warning characters are printed on said embedded positioned block. The external body of said power plug is made by injection modeling with mixed transparent PVC and thermochromic materials, or the embedded positioned block may be directly injected with thermochromic materials, or connected with a detecting transistor linked by a light emitting diode (LED). When the power plug is over-heated and the temperature of the power plug gradually increases, the thermochromic materials or the LED will display a warning message. | 1. A power plug with overloaded display, comprising an embedded positioned block arranged on the periphery of the electric metal-pin of said power plug, wherein a thermochromic film is coated on the surface of said embedded positioned block, and the external body of said power plug is made by injection modeling with transparent PVC, therefore, users can be noted or warned that said power plug is under unusual temperature increasing condition by color change of the thermochromic film coated on said power plug, after said power plug is overloaded. 2. The power plug with overloaded display according to claim 1, wherein said embedded positioned block is printed with warning characters made of thermochromic materials. 3. The power plug with overloaded display according to claim 1, wherein said external body of said power plug made by injection modeling is injected by mixing the thermochromic materials with PVC. 4. The power plug with overloaded display according to claim 1, wherein said embedded positioned block is directly injection modeled with thermochromic materials. 5. The power plug with overloaded display according to claim 1, wherein the melting joint between said electric metal-pin and a power wire is extendedly connected with a detecting transistor and a light emitting diode (LED), and the top of said LED is exposed outside the surface of said electric plug, hence, when said detecting transistor detects that said power plug is overloaded, said LED will be flashed to note or warn users that the temperature of said power plug is abnormally increasing. 6. The power plug with overloaded display according to claim 4, wherein said LED connected with said detecting transistor is embedded into the external body of said power plug injected with transparent PVC. | BACKGROUND OF THE INVENTION Generally, electric equipment using alternating current usually is plugged into an alternating current plug by a power plug through wires. As we know, alternating current power source generally is divided into 2 types, 110 voltage and 220 voltage. At present, the most common structure applied for power plug comprises 2 or 3 electric metal-pins ( hot, neutral, and ground), wherein one end of the electric metal-pins is connected with the copper core of wires, after connecting, the back section of the electric metal-pins and a predetermined length of wire are molded or injection modeled with PVC to form an external body of the power plug, and the external body is suitable for being held by hand. The external body comprises a flexible rear fin, and enables the front section of the electric metal-pins exposed outside the power plug to contact the electric metal-sheet for conducting electricity, in this way, a power plug made of PVC is completed. As we know, the electric metal-pin of a power plug generally is the easiest part to accumulate heat when using, especially the part between electric metal-pins and core of the wires usually is the key place for shorts and fires. If the equipment is overloaded, the temperature will increase. Therefore, the PVC of the conventional used power plug, which contacts the electric metal-pins, will be hardened after a period time of using because of heat, resulting in the position changing between the two electric metal-pins or deforming the power plug. When in an abnormal overload condition and the temperature in electric metal-pins is increasing, if users do not shut down the power in time and check the equipment, which will melt the PVC and result in high temperature sparks. These conditions will make electric wires or equipment catch fire more easily, even resulting in fire accidents. Then, if the conventional power plug can display a warning function when abnormal temperature increases, accidents will be avoided at an early stage. SUMMARY OF THE INVENTION A power plug with overloaded display, which provides users with the function of warning display for protecting the power plug from over-heated melting, wherein an embedded positioned block is arranged on the periphery of the electric metal-pin of said power plug, and a thermochromic film is coated on the surface of said embedded positioned block, and warning characters are printed on said embedded positioned block. The external body of said power plug is made by injection modeling with mixed transparent PVC and thermochromic materials, or the embedded positioned block may be directly injected with thermochromic materials, or connected with a detecting transistor linked by a light emitting diode( LED). The appearance of the power plug is formed like a plug by being injected with transparent PVC. When the power plug is over-heated and the temperature of the power plug gradually increases, the thermochromic film will change its color to warn users or the LED will flash to protect the power plug from over-heated melting or from shorting and catching on fire. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a three-dimensional view showing the power plug with overloaded display of the present invention; FIG. 2 is a three-dimensional view showing the power plug with overloaded display, which is made of thermochromic materials and printed with warning characters of the present invention; FIG. 3 is a three-dimensional view showing the power plug made by injection modeling with mixed thermochromic materials and PVC; FIG. 4 is the perspective view showing the power plug with overloaded display and arranged with a detecting transistor of the present invention; FIG. 5 is the perspective view of FIG. 3 of the present invention; and FIG. 6 is the cross-section view for another example of FIG. 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION The power plug with overloaded display of the present invention is as shown in FIG. 1. The present invention relates to embedding an orientated block (2) on the periphery of the electric metal-pins (11) of a power plug (1), wherein the embedded positioned block (2) is made of fire-resistant, and high intensity materials insulated against electricity and heat, and arranged with positioned metal-pins (11), such as PBT ( Polybutylene Terephthalate) . . . etc. The embedded positioned block (2) may be coated with thermochromic film (21), or be formed by directly injected with thermochromic materials (23), and the appearance of the external body (5) of the power plug is formed like a plug by injection modeling with transparent PVC. As above mentioned, when the power plug is overloaded and the temperature of it increases under use, users can be noted or warned that the power plug is under unusual temperature increasing condition by the color change of the thermochromic film (21), or by the color change of the embedded positioned block (23) containing thermochromic materials, for security control such as shutting down the power immediately . . . etc, which protects the power plug from over-heated melting or form shorting and catching on fire. As shown in FIG. 2, the surface of the above mentioned embedded positioned block (2) may also be printed with warning characters (22) (such as overload, or danger) containing thermochromic materials, wherein the warning characters will change its color when the power plug is overloaded and its temperature increases. In this way, users also can be noted or warned that the power plug's temperature is unusually increasing. As shown in FIG. 3, the external body (51) of the power plug of the present invention may also be injection modeled with mixed thermochromic materials and PVC to change its color to warn users when the power plug is overloaded and the temperature is increasing. With the above mentioned methods for warning, as shown in FIG. 4 and FIG. 5, the present invention furthermore may comprise a detecting transistor (3) arranged on the power plug, and connect with a light emitting diode (LED, 4). The top of the LED is exposed outside the surface of the external body (5) of the power plug (which makes the materials for the injected external body (5) not only limited in transparent materials), or as shown in FIG. 6, the LED (4) is arranged with the external body (5) of the power plug injection modeled with transparent PVC materials. Hence, when the detecting transistor (3) detects that power plug (1) is overloaded, the LED (4) will be flashed to note or warn users that the temperature of the power plug is in abnormal increasing condition, to protect the power plug from over-heated melting or from shorting and catching on fire. | <SOH> BACKGROUND OF THE INVENTION <EOH>Generally, electric equipment using alternating current usually is plugged into an alternating current plug by a power plug through wires. As we know, alternating current power source generally is divided into 2 types, 110 voltage and 220 voltage. At present, the most common structure applied for power plug comprises 2 or 3 electric metal-pins ( hot, neutral, and ground), wherein one end of the electric metal-pins is connected with the copper core of wires, after connecting, the back section of the electric metal-pins and a predetermined length of wire are molded or injection modeled with PVC to form an external body of the power plug, and the external body is suitable for being held by hand. The external body comprises a flexible rear fin, and enables the front section of the electric metal-pins exposed outside the power plug to contact the electric metal-sheet for conducting electricity, in this way, a power plug made of PVC is completed. As we know, the electric metal-pin of a power plug generally is the easiest part to accumulate heat when using, especially the part between electric metal-pins and core of the wires usually is the key place for shorts and fires. If the equipment is overloaded, the temperature will increase. Therefore, the PVC of the conventional used power plug, which contacts the electric metal-pins, will be hardened after a period time of using because of heat, resulting in the position changing between the two electric metal-pins or deforming the power plug. When in an abnormal overload condition and the temperature in electric metal-pins is increasing, if users do not shut down the power in time and check the equipment, which will melt the PVC and result in high temperature sparks. These conditions will make electric wires or equipment catch fire more easily, even resulting in fire accidents. Then, if the conventional power plug can display a warning function when abnormal temperature increases, accidents will be avoided at an early stage. | <SOH> SUMMARY OF THE INVENTION <EOH>A power plug with overloaded display, which provides users with the function of warning display for protecting the power plug from over-heated melting, wherein an embedded positioned block is arranged on the periphery of the electric metal-pin of said power plug, and a thermochromic film is coated on the surface of said embedded positioned block, and warning characters are printed on said embedded positioned block. The external body of said power plug is made by injection modeling with mixed transparent PVC and thermochromic materials, or the embedded positioned block may be directly injected with thermochromic materials, or connected with a detecting transistor linked by a light emitting diode( LED). The appearance of the power plug is formed like a plug by being injected with transparent PVC. When the power plug is over-heated and the temperature of the power plug gradually increases, the thermochromic film will change its color to warn users or the LED will flash to protect the power plug from over-heated melting or from shorting and catching on fire. | 20040402 | 20061010 | 20051006 | 72041.0 | 0 | NASRI, JAVAID H | POWER PLUG WITH OVERLOADED DISPLAY | SMALL | 0 | ACCEPTED | 2,004 |
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10,815,879 | ACCEPTED | Process for the monoalkylation of dihydroxy aromatic compounds | A continuous process comprising: contacting a mixture comprising dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, to form a mono alkylated dihydroxy aromatic compound, wherein the catalyst system is obtained by the calcination of a catalyst precursor system comprising a metal oxide precursor, a transition metal element and a pore former. | 1. A continuous process comprising: contacting a mixture comprising a dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, to form a mono alkylated dihydroxy aromatic compound, wherein said catalyst system is obtained by the calcination of a catalyst precursor system comprising a metal oxide precursor, a transition metal element and a pore former. 2. The process of claim 1, wherein said compound has a formula: wherein R is hydrogen and each occurrence of R1 is independently selected from the group consisting of hydrogen and a hydrocarbyl group selected from the group consisting of an alkyl group containing 1 to about 18 carbon atoms, an aryl group containing about 6 to about 20 carbon atoms, an arylalkyl group containing about 7 to about 12 carbon atoms and an alkylaryl group containing about 7 to about 16 carbon atoms. 3. The process of claim 1, wherein said dihydroxy aromatic compound is selected from the group consisting of hydroquinone, resorcinol, catechol, 2-methyl hydroquinone, 2,5-dimethyl hydroquinone, 2-ethyl hydroquinone, 2,5-diethyl hydroquinone, 2-tertiarybutyl hydroquinone 2,5-ditertiarybutyl hydroquinone, 2-phenyl hydroquinone, 2-benzyl hydroquinone, 2,3,5-trimethyl hydroquinone, 2-vinyl hydroquinone, 2-isopropyl hydroquinone, 2,5-diisopropyl hydroquinone, and mixtures of two or more of the foregoing dihydroxy aromatic compound. 4. The process of claim 1, wherein said dihydroxy aromatic compound comprises hydroquinone. 5. The process of claim 1, wherein said alkylating agent is selected from a group consisting of branched chain or straight chain alkyl alcohols containing 1 to 16 carbon atoms and branched chain or straight chain olefins containing 2 to 16 carbon atoms. 6. The process of claim 1, wherein said alkylating agent is selected from a group consisting of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, amyl alcohol, isoamyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, cetyl alcohol, cyclohexyl alcohol, cyclohexylmethyl alcohol, ethylene, propylene, 1-butylene, 2-butylene, isobutylene, 1-pentene, 2-pentene, 2-methylpentene-2, 3-methylpentene-2, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, the isomeric octenes, nonenes and decenes. 7. The process of Claim 1, wherein said alkylating agent comprises methyl alcohol. 8. The process of claim 1, wherein said metal oxide precursor is selected from a group consisting of magnesium oxide precursor, lanthanum oxide precursor, chromium oxide precursor, vanadium oxide precursor, copper oxide precursor, lanthanum oxide precursor and mixtures of two or more of the foregoing. 9. The process of claim 1, wherein said metal oxide precursor comprises a magnesium oxide precursor. 10. The process of claim 1, wherein said metal oxide precursor comprises magnesium carbonate. 11. The process of claim 1, wherein said transition metal element comprises copper. 12. The method of claim 1, wherein the pore former is selected from a group consisting of waxes and polysaccharides. 13. The method of claim 1, wherein the pore former comprises polyethylene glycol. 14. The process of claim 1, wherein said contacting is carried out at a weighted hourly space velocity of 0.1 to 10. 15. The process of claim 1, wherein the molar ratio of alkylating agent to dihydroxy aromatic compound is 0.5 to 4. 16. The process of claim 1, wherein the carrier gas is selected from a group consisting of nitrogen, hydrogen, helium, argon, carbon monoxide and mixtures of two or more of the foregoing gases. 17. The process of claim 1, wherein monoalkylation of the dihydroxy aromatic compound is carried out at a temperature of 300° C. to 500° C. 18. The process of claim 1, wherein the mixture further comprises a diluent. 19. The process of claim 18, wherein the diluent is selected from a group consisting of monoglyme, diglyme, triglyme, tetraglyme, butyl diglyme, glycol, polyglycol and dipropylene glycol dimethyl ether. 20. The process of claim 18, wherein the diluent is monoglyme. 21. The process of claim 18, wherein the molar ratio of diluent to dihydroxy aromatic compound is about 0.1 to about 10. 22. The process of claim 1, wherein the catalyst has pores having pore diameters of 100 to 400 Angstroms. 23. A continuous process comprising: contacting a mixture comprising a dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, to form a mono alkylated dihydroxy aromatic compound, wherein said catalyst system has pores having diameters of 100 to 400 Angstroms. 24. The process of claim 23, wherein said contacting is done at a weighted hourly space velocity of 0.1 to 10. 25. A continuous process comprising: contacting a mixture of hydroquinone, monoglyme, water and methanol with a catalyst system in the presence of flowing nitrogen gas, to form 2-methyl hydroquinone, wherein said catalyst system comprising magnesium oxide and copper is obtained by the calcination of a catalyst precursor system, wherein said catalyst precursor system comprises magnesium carbonate, copper and poly ethylene glycol. 26. The process of claim 25, wherein said contacting is done at a weighted hourly space velocity of 0.1 to 10. 27. A polycarbonate comprising subunits derived from the mono alkylated dihydroxy compound prepared according to claim 1. 28. A polycarbonate produced by melt polymerization of a diphenyl carbonate and a mixture of dihydroxy aromatic compounds comprising a mono alkylated dihydroxy aromatic compound in the presence of a catalyst wherein the mono alkylated dihydroxy compound was prepared by the method of claim 1. | BACK GROUND OF INVENTION The disclosure generally relates to alkylation of dihydroxy aromatic compounds. More particularly the disclosure relates to selective mono ortho alkylation of dihydroxy aromatic compounds. An alkylation reaction of a dihydroxy aromatic compound typically involves a vapor phase reaction of a dihydroxy aromatic compound with an alcohol using an alkylation catalyst. Such alkylated dihydroxy aromatic compounds find applications in a wide range of industries including, among others, the polymer industry, the dye industry, the photographic industry and in medical applications. They are also known for fabricating polycarbonates for use in liquid crystal displays. Many alkylation processes for hydroxy aromatic compounds use metal oxide catalysts. Many of the alkylating catalysts produce a mixture that often contains a high proportion of dialkylated hydroxy aromatic compounds with very low selectivities towards mono alkylated hydroxy aromatic compounds. Dihydroxy aromatic compounds tend to be more reactive than hydroxy aromatic compounds thereby having an even greater tendency to generate higher alkylated and oligomeric products and making the production of mono alkylated products more difficult. Thus, there exists an ongoing need for improvement in the process for the preparation of mono alkylated dihydroxy aromatic compounds, particularly mono ortho-alkylated dihydroxy aromatic compounds. SUMMARY OF INVENTION A continuous process comprising: contacting a mixture comprising dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, to form a mono alkylated dihydroxy aromatic compound, wherein said catalyst system is obtained by the calcination of a catalyst precursor system comprising a metal oxide precursor, a transition metal element and a pore former. The above-described method may be understood more readily by reference to the following detailed description of the various features of the disclosure and the examples included therein. DETAILED DESCRIPTION Disclosed herein is a process for mono alkylation of dihydroxy aromatic compounds providing a high degree of selectivity towards mono alkylation, particularly mono ortho alkylation. The process of mono alkylating a dihydroxy aromatic compound comprises contacting a reaction mixture comprising the dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, at a weighted hourly space velocity, to form a mono alkylated dihydroxy aromatic compound, wherein said catalyst system is obtained by the calcination of a catalyst precursor system. The reaction mixture may further comprise a diluent. The catalyst precursor system comprises a metal oxide precursor, a transition metal and a pore former. After calcination the metal oxide precursor is converted to the metal oxide and the calcined catalyst may have pores with average pore diameters of 100 to 400 Angstroms. The singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. Whenever a range of values are given it should be understood that it includes all subranges contained therein. Unless otherwise specified, the term “alkyl” as used herein is intended to designate straight chain alkyls and branched alkyls. The straight chain and branched alkyl groups include as illustrative non-limiting examples, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl and tertiary-butyl groups. The dihydroxy aromatic compounds may be selected from the group consisting of hydroquinone compounds, resorcinol compounds and catechol compounds. In one embodiment the dihydroxy aromatic compounds are of the formula: wherein R is a hydrogen group and each occurrence of R1 is independently selected from the group consisting of a hydrogen and a hydrocarbyl group selected from the group consisting of an alkyl group containing 1 to 18 carbon atoms, an aryl group containing about 6 to 20 carbon atoms, an arylalkyl group containing about 7 to 12 carbon atoms and an alkylaryl group containing about 7 to 16 carbon atoms. Specific examples of suitable dihydroxy aromatic compounds include hydroquinone, resorcinol, catechol, 2-methyl hydroquinone, 2,5-dimethyl hydroquinone, 2-ethyl hydroquinone, 2,5-diethyl hydroquinone, 2-tertiarybutyl hydroquinone 2,5-ditertiarybutyl hydroquinone, 2-phenyl hydroquinone, 2-benzyl hydroquinone, 2,3,5-trimethyl hydroquinone, 2-vinyl hydroquinone, 2-isopropyl hydroquinone, 2,5-diisopropyl hydroquinone, and mixtures of two or more of the foregoing dihydroxy aromatic compounds. An alkylating agent is a reactant, which under the conditions described herein reacts with a dihydroxy aromatic compound to provide a mono alkylated dihydroxy aromatic compound. The alkylating agents used in the process may be selected from the group consisting of branched chain or straight chain alkyl alcohols containing 1 to 16 carbon atoms and branched chain or straight chain olefins containing 2 to 16 carbon atoms. Exemplary alkyl alcohols include methyl alcohol, ethyl alcohol, 2-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, amyl alcohol, isoamyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, cetyl alcohol, cyclohexyl alcohol, and cyclohexylmethyl alcohol. Exemplary olefins include ethylene, propylene, 1-butylene, 2-butylene, isobutylene, 1-pentene, 2-pentene, 2-methylpentene-2, 3-methylpentene-2, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene, 3-heptene, the isomeric octenes, nonenes and decenes. In one embodiment the alkylating agent is methanol. The molar ratio of the alkylating agent to the dihydroxy aromatic compound is 0.5 to 4 moles per mole of dihydroxy aromatic compound or, more specifically, the molar ratio is 1 to 3.5 moles per mole of dihydroxy aromatic compound, or, even more specifically, the molar ratio is 2 to 3 moles per mole of dihydroxy aromatic compound. It is to be understood that the aforementioned dihydroxy aromatic compounds and alkylating agents are only representative of the class of compounds that may be employed. Methods of preparing the catalysts systems described herein are disclosed in commonly assigned, co-pending U.S. patent application Ser. No. 10/065134. The catalyst system employed is obtained by the calcination of a catalyst precursor system comprising at least one metal oxide precursor, which is converted to a metal oxide during calcination, a promoter and a pore-former. Metal oxide precursors include magnesium oxide precursors, iron oxide precursors, chromium oxide precursors, vanadium oxide precursors, copper oxide precursors, lanthanum oxide precursors and mixtures of two or more of the foregoing. The metal oxide precursor may comprise any metal reagent which yields the corresponding metal oxide under calcination conditions such as nitrates, carbonates, oxides, hydroxides, sulphates and mixtures of two or more of the foregoing. For example, any magnesium reagent which yields magnesium oxide after calcination can be used. In one embodiment the metal oxide precursor comprises magnesium hydroxide, magnesium nitrate, magnesium carbonate, magnesium sulphate, magnesium acetate or a mixture of two or more of the foregoing. In another embodiment the metal oxide precursor comprises magnesium carbonate. The pore former used in the catalyst system is a substance capable of aiding the formation of pores in the catalyst. Under the calcination condition described herein the pore former decomposes or bums off leaving behind pores in the catalyst. The pore former may be selected from the group consisting of waxes and polysaccharides. Exemplary waxes include, but are not limited to, paraffin wax, polyethylene wax, microcrystalline wax, montan wax, and combinations of two or more of the foregoing. Exemplary polysaccharides may be cellulose, carboxyl methyl cellulose, cellulose acetate, starch, walnut powder, citric acid, polyethylene glycol, oxalic acid, stearic acid and combinations of two or more of the foregoing. Also useful are anionic and cationic surfactants, typically long chain (C10-28) hydrocarbons containing neutralized acid species, e.g., carboxylic acid, phosphoric acid, and sulfonic acid species. In one embodiment the pore former is polyethylene glycol. The amount of the pore former employed is that which provides for average pore diameters of 100 to 400 Angstroms (Å) after calcination. The amount of pore former may be 100 ppm to 10 wt %, or, more specifically, 100 ppm to about 5 weight percent, or, even more specifically, up to 2 weight percent with respect to catalyst precursor reagent. The pore former is typically blended with the metal oxide precursor and transition metal to provide uniform distribution of the pore former along with other components of the catalyst such as binders and fillers. Transition metal elements are used as promoters in the catalyst system. Specific examples of suitable transition metal elements include copper, chromium, zinc, cobalt, nickel, manganese and mixtures of two or more of the foregoing. In one embodiment the promoter is copper. The catalyst precursor system is converted to the catalyst through calcination. In one embodiment gas, such as air, nitrogen, or a combination thereof, is passed through the catalyst precursor system during all or part of the calcination. The catalyst precursor system may be heated prior to calcination and heating may also occur with gas flow. It is believed that gas flow may aid in the formation of pores having the desired pore size. Calcination is usually carried out by heating the catalyst at a temperature sufficient to convert the metal oxide precursor to the corresponding metal oxide. Useful calcination procedures are found in U.S. Pat. Nos. 6,294,499 and 4,554,267. The calcination temperature may vary somewhat, but is usually 350° C. to 600° C. Slow heating rates can lead to desirable larger pore sizes but often at the expense of lower activity of the resultant catalyst. Typically, the heating rate for commercial scale will be to raise the temperature from ambient to 400° C. over a 12 to 18 hour range although the exact rate can vary depending on the actual reactor size and geometry. The calcination atmosphere may be oxidizing, inert, or reducing. Alternatively, the catalyst can be calcined at the beginning of the alkylation reaction. In other words, calcination can take place in the presence of the alkylation feed materials, i.e., the dihydroxy aromatic compound and the alkyl alcohol. The surface area of the catalyst after calcination is usually 100 m2/g to 250 m2/g, based on grams of metal oxide. In one embodiment the catalyst has, after calcination, a distribution of pores having an average size of 100 Å to 400 Å in diameter. The metal oxide alkylation catalyst may have a bimodal distribution of pores. In one embodiment the bimodal distribution of pores has a first distribution of pores wherein the first distribution has an average pore diameter less than 100 Angstroms and a second distribution of pores wherein the second distribution has an average diameter greater than 100 Angstroms and less than 400 Angstroms. Without being bound by theory it is believed that these large pores in the catalyst may reduce the retention time of the substrate, thereby increasing the mono-alkyl selectivity. Without being bound by theory, it is believe that the presence of water in the reaction mixture helps to reduce coke formation. Water also serves as a diluent. The amount of water added is 1 mole to 10 moles per mole of the aromatic dihydroxy compound or, more specifically, 2 to 8 moles per mole of the aromatic dihydroxy compound, or, even more specifically, 3 to 5 moles per mole of the aromatic dihydroxy compound. The reaction mixture comprising dihydroxy aromatic compound, water and alkylating agent can additionally comprise a diluent to facilitate the reaction. The diluents employed in the reaction are selected from the group consisting of solvents that vaporize or are in a vapor state at the temperatures of 300° C. to 500° C. and are stable and undergo little or no decomposition in this temperature range. Suitable examples of diluent include, but are not limited to, monoglyme, diglyme, triglyme, tetraglyme, butyl diglyme, glycol, polyglycol and dipropylene glycol dimethyl ether. In one embodiment the diluent is monoglyme. The amount of diluent used is 0.1 mole to 10 moles per mole of dihydroxy aromatic compound, or, more specifically, 1 to 8 moles per mole of dihydroxy aromatic compound, or, even more specifically, 1 to 2 moles per mole of dihydroxy aromatic compound. The alkylation reaction occurs at a temperature of 300° C. to 500° C., or, more specifically, at a temperature of 400° C. to 500° C., or, even more specifically, at a temperature of 440° C. to 480° C. Inert carrier gases that may be used in the alkylation process include, but are not limited to, nitrogen, hydrogen, helium, argon, carbon monoxide and mixtures of two or more of the foregoing gases. In one embodiment the carrier gas employed comprises nitrogen. The amount of carrier gas used is 1 mole to 12 moles per mole of dihydroxy aromatic compound, or, more specifically, 5 moles to 10 moles of dihydroxy aromatic compound, or, even more specifically, 6 moles to 8 moles per mole of dihydroxy aromatic compound. The weighted hourly space velocity (WHSV) of the feed is 0.1 to 10, or, more specifically, 2 to 5, or, even more specifically, 1 to 3. The weighted hourly space velocity is the mass of feed per unit of catalyst per unit of time. In an exemplary procedure a reactor is loaded with the catalyst precursor system prepared as given above. It is then calcined in-situ for about 22 hours at about 390° C. under an inert atmosphere of nitrogen gas, at atmospheric pressure. After calcination, the temperature is increased to about 400-500° C. over a period of two hours under an inert atmosphere of nitrogen gas. A premixed solution of the feed mixture comprising dihydroxy aromatic compound, alkylating agent, diluent and water, is introduced at a desired flow rate measured in terms of WHSV. Alternatively, in the absence of a diluent in the reaction, a first feed stream comprising dihydroxy aromatic compound in the molten state is added simultaneously with a second feed stream comprising water and alkylating agent. The process described herein may have a selectivity for mono ortho alkylated products greater than or equal to 50%, or, more specifically, greater than or equal to 60%, or, even more specifically, greater than or equal to 70%. Selectivity is calculated as described below in the Examples. As previously discussed, the mono alkylated dihydroxy aromatic compounds find various end use applications in the polymer, dyestuff, pharmaceutical, photographic industries and in medical applications. Polycarbonates particularly containing mono alkylated dihydroxy aromatic units are known to exhibit liquid crystalline properties. Suitable methods for preparation of these polycarbonates include melt- polymerization reaction of diphenylcarbonate and mixtures of dihydroxy compounds comprising mono alkylated dihydroxy aromatic compounds such as methyl hydroquinone in the presence of quaternary phosphonium salts, sodium hydroxide or tetraalkylammonium salts as catalyst systems. The mono alkylated dihydroxy aromatic compounds can also be used to prepare polyesters when coupled with other monomers by melt polymerization techniques as is known in the art. The process is further described by the following non-limiting examples. EXAMPLES In the following examples and comparative examples, a high performance liquid chromatography (HPLC) method was used to quantify the conversion of a dihydroxy aromatic compound to a mono ortho-alkylated dihydroxy aromatic compound. The HPLC was initially calibrated using standard Aldrich samples of hydroquinone (HQ), and 2-methyl hydroquinone (2-Me HQ) and 2,6-dimethyl hydroquinone (2,6 di Me HQ). The standard samples were diluted with an internal standard solution of N-methyl benzamide in acetonitrile and injected into a C-18 reverse phase column. Each reaction mixture sample was diluted with an internal standard solution of N-methyl benzamide in acetonitrile and injected into a C-18 reverse phase column. Samples at specific time intervals were analyzed and compared to the HPLC chromatogram of the standard sample to determine the conversion of hydroquinone and selectivity towards formation of 2-methyl hydroquinone and 2,6-dimethyl hydroquinone. Example: 1 A dry mixture of 100 grams (gms) of magnesium carbonate, 2.5 gms of polyethylene glycol, 1 gram (gm) graphite, and 1000 ppm of copper nitrate was prepared. This mixture was pelletized and crushed to particles having a size of 800-1400 micrometers to provide the catalyst precursor system. Examples 2-10: A glass reactor was loaded with 5 grams of the catalyst precursor system prepared in example 1. The catalyst was calcined in-situ for 22 hours at 390° C. under a flow of nitrogen, at atmospheric pressure. After calcination, the temperature was increased to 480° C. over a period of two hours under a nitrogen atmosphere. After 15 minutes, a feed mixture comprising hydroquinone, methanol (MeOH), monoglyme and water, was introduced at the flow rates indicated by the weighted hourly space velocity (WHSV) in Table 1. The molar ratio of hydroquinone to monoglyme to water was maintained at 1:2:3 and the carrier gas to hydroquinone molar ratio was maintained at 8:1. The temperature of the feed mixture and the molar ratio of methanol to hydroquinone were varied as indicated in Table 1. The alkylation was run for 24 hours under the above mentioned conditions during which methyl hydroquinone selectivity and dimethyl hydroquinone selectivity were monitored on HPLC. Samples for measuring conversion and selectivity were withdrawn as indicated by the time of sampling (TOS) data indicated in Table 1 below. 2-Methyl hydroquinone selectivity was calculated as follows: 2-MeHQ selectivity=(moles of 2-MeHQ formed/moles of HQ converted) *100%. TABLE 1 HQ conversion 2-MeHQ 2,6-di Me HQ Time of sampling Temp in selectivity in selectivity in Ex. HQ in moles MeOH/HQ in hours WHSV in ° C. mole % mole % mole % 1 1 3 10 1.3 480 25 75 13 2 1 2 10 1 480 50 32 20 3 1 3 10 1.3 465 27 53 15 4 1 4 10 1.6 480 30 55 26 5 1 2 10 1.6 480 24 63 10 61 1 3 10 1.3 480 38 44 17 72 1 3 24 1.3 480 15 64 13 1Hydrogen as the carrier gas 25 moles of water per mole of hydroquinone. These experiments indicate that the use of polyethylene glycol pore-former in the catalyst precursor system increases the selectivity towards 2-methyl hydroquinone. The presence of the pore former in the catalyst precursor provides larger pore sizes in the catalyst system on calcination. Without being bound by theory it is belived that the 2-methyl hydroquinone may diffuse out faster from the larger catalyst pores, thus reducing the over alkylation due to reduced contact time with the catalyst. Comparative Example A similar procedure was followed as in examples 2-10, except that the catalyst precursor contained only magnesium carbonate. Results are shown in Table 2. TABLE 2 HQ Time of conversion 2-MeHQ 2,6-di Me HQ HQ in sampling Temp in selectivity in selectivity in Ex. moles MeOH/HQ in hours WHSV in ° C. mole % mole % mole % Comp 1 3 10 1.3 480 34 49 15 Ex. 1 As can be seen by a comparison of Example 1 and Comparative Example 1 use of only magnesium carbonate as the catalyst precursor in the absence of a promoter and pore-former shows decreased selectivity towards 2-methyl hydroquinone under similar operating conditions. The foregoing examples show that the use of a catalyst having pore size of 100 to 400 Å results in an alkylation process for dihydroxy aromatic compounds that has surprisingly high selectivity for mono alkylated products, particularly mono ortho alkylated products. While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. All patents and patent applications cited herein are incorporated by reference. | <SOH> SUMMARY OF INVENTION <EOH>A continuous process comprising: contacting a mixture comprising dihydroxy aromatic compound, water and an alkylating agent with a catalyst system in the presence of a flowing carrier gas, to form a mono alkylated dihydroxy aromatic compound, wherein said catalyst system is obtained by the calcination of a catalyst precursor system comprising a metal oxide precursor, a transition metal element and a pore former. The above-described method may be understood more readily by reference to the following detailed description of the various features of the disclosure and the examples included therein. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20060808 | 20051006 | 97379.0 | 0 | BOYKIN, TERRESSA M | PROCESS FOR THE MONOALKYLATION OF DIHYDROXY AROMATIC COMPOUNDS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,893 | ACCEPTED | Scale for use with a translation and orientation sensing system | A position sensor using a novel structured light generating scale or target member is provided. An imaging array is capable of measuring the relative translation and orientation of the structured light generating scale or target member in X, Y, Z, yaw, pitch, and roll (“6D”) simultaneously, and with high precision. The target member includes an array of lenses that provide an array of structured light patterns that diverge, converge, or both, to change the size of the corresponding structured light image as a function of the “Z” coordinate of the relative position, in various embodiments. The X-Y position of each individual structured light image on the imaging array varies with the relative X-Y position of the structured light generating target member, and the shape of structured light image changes as a function of the relative angular orientation. Accordingly, three or more structured light images analyzed in the same image are usable to determine a 6D measurement between the structured light generating target member and the array detector. X and Y displacement of the target member can be accumulated by known methods and the other 6D measurement components are absolute measurements at any position. | 1. A position measuring device usable for measuring a relative position between two members, the position measuring device comprising: an imaging detector; and a structured light generating target member, wherein: the imaging detector and the structured light generating member are positionable to provide an image on the array detector that corresponds to a structured light pattern generated by at least a portion of the structured light generating target member; and the image on the array detector is usable to determine at least one measurement value that corresponds to at least one degree of freedom of the relative position between the imaging detector and the target member. | FIELD OF THE INVENTION This invention relates generally to optical position sensors, and, more particularly, to a multi-axis optical position sensor utilizing a structured light scale or target. BACKGROUND OF THE INVENTION Various accurate 2-dimensional (2D) optical position sensing systems are known. For example, one 2D incremental position sensor using a 2D grating scale and providing high resolution and high accuracy for sensing translation in an X-Y plane is disclosed in U.S. Pat. No. 5,104,225 to Masreliez, which is incorporated herein by reference in its entirety. Such a system is essentially an orthogonal combination of well known 1-dimensional (1D) optical encoder “incremental” measurement techniques that sense the position of a readhead within a particular period of a periodic scale grating for high resolution and continuously increment and decrement a count of the number of periods of the periodic scale that are traversed during a series of movements, in order to continuously provide a net relative displacement between the readhead and scale. However, such systems cannot sense the “z-axis” separation between a readhead and scale. A very limited number of types of optical position sensors capable of sensing more than two degrees of freedom of a relative position of an object are known. One system comprising a probe that can sense relative position for up to 6 degrees of freedom is disclosed in U.S. Pat. No. 5,452,838 to Danielian and Neuberger. The '838 patent discloses a probe using a fiber optic bundle, with individual fibers or sets of fibers acting as individual intensity sensing channels. The individual intensity signals vary with X-Y motion of an illuminated target surface, as well as with the proximity of each fiber to the illuminated target surface along a direction normal to the surface. However, the probe disclosed in the '838 patent provides relatively crude measurement resolution and a limited sensing range for “z-axis” separation and orientation between the probe and a target surface. Known dual-camera “stereoscopic” triangulation systems can sense relative position for up to 6 degrees of freedom. However, such known dual-camera systems are generally relatively large systems developed for measuring macroscopic objects and/or their positions, which do not scale well to relatively compact precision position measuring systems usable in close proximity to their target object. Furthermore, the triangulation arrangement of such known systems generally constrains the relationship between the z-axis measurement resolution and the z-axis measurement range in a restrictive and undesirable manner. Systems that can image an object and determine x-y position from a feature in the image and z-axis position and orientation based on varying magnification in the image are also known. However, the magnification arrangement of such known systems generally constrains the relationship between the z-axis measurement resolution and the z-axis measurement range in a restrictive and undesirable manner, and introduces other problems requiring special image processing and/or compensation in order to accurately measure a relative position with up to 6 degrees of freedom. SUMMARY OF THE INVENTION The present invention is directed to providing a position sensor that overcomes the foregoing and other disadvantages. More specifically, the present invention is directed to an optical position sensor utilizing a scale or target member that emits a structured light pattern (also referred to as a structured light scale, structured light target, or structured light target member), and an imaging array (also referred to as a camera, image detector, optical detector or array detector), to provide high accuracy simultaneous measurements for up to 6 degrees of freedom for an object (multiple-dimension, or “6D”, measurements), including any one of, or combination of, X, Y, Z, yaw, pitch, and roll. Depending on the design parameters chosen for the structured light pattern and the imaging array, the applications of an optical position sensor according to this invention include, but are not limited to, precision position sensors for metrology, motion control systems and the like, as well as relatively lower resolution and/or longer range sensors usable for computer input devices, multi-degree-of-freedom manual machine controllers, macroscopic object ranging and orientation measurement systems, and the like. In accordance with one aspect of the invention, the imaging array is positionable to input a structured light image (also referred to as a target image) arising from the structured light sources (also referred to target sources) on a target member. In various exemplary embodiments, the target sources are arranged in a two-dimensional periodic array on the target member. In accordance with another aspect of the invention, the image on the array detector includes respective image features corresponding to respective target sources on the target member. In accordance with another aspect of the invention, in various exemplary embodiments, the target sources create a diverging structured light pattern. In various other embodiments, the target sources create a converging structured light pattern. In various other embodiments, the target sources create a structured light pattern that converges and then diverges along the central axis of the structured light pattern. In various exemplary embodiments, a target source comprises a refractive axicon point-like lens (an axicon point), a refractive axicon ring, a refractive faceted pyramidal-type point-like lens, a refractive polyhedral-like arrangement of prismatic “lines”, an arrangement of one or more refractive prismatic “lines”, or any combination thereof. In various other exemplary embodiments respective diffractive optical elements, that deflect light rays approximately like the corresponding respective refractive optical elements listed above, may be used instead of refractive optical elements. In accordance with another aspect of the invention, a target source receives collimated light from a light source and outputs the structured light pattern. In accordance with a further aspect of the invention, the target source further comprises a lens or lens portion that causes adjacent rays of the structured light to focus at a plane that is located approximately in the middle of a nominal measuring range along an axis of separation between the imaging array and the target member. In accordance with a further aspect of the invention, in various embodiments where the target source is a point-like lens, the rays of the structured light pattern are arranged at a polar angle relative to an axis that extends from the target source along a direction normal to a face of the target member. The particular polar angle is determined by the characteristics of the point-like lens. The polar angle is furthermore the cone angle of a hypothetical cone with an apex proximate to the target source. Thus, in accordance with a further aspect of the invention, in various exemplary embodiments, the structured light image on the imaging detector (also referred to as an array detector) comprises a continuous, or segmented, circular or elliptical pattern formed where the hypothetical cone intersects with the plane of the optical detector elements of the imaging array. In various embodiments, the segments of the circular or elliptical pattern are essentially spots. In accordance with a further aspect of the invention, the continuous or segmented circular or elliptical (ring-shaped) image corresponding to a target source has a size that varies with the separation along a direction parallel to an axis of separation between the imaging array and the target member. The size of the ring-shaped structured light image corresponding to a target source can thus be used to determine an absolute z-axis coordinate for a corresponding target source or other reference feature relative to the detection plane, or reference plane, of the imaging array. In accordance with a further aspect of the invention, the location of the center of the ring-shaped structured light image corresponding to a target source on the array detector can be used to determine the location of the corresponding target source along a plane parallel to the detection plane, or reference plane, of the imaging array, and can thus be used to determine the displacement of the target source relative to the detection plane, or reference plane, of the imaging array along an x-y plane. Thus, a set of (x,y,z) coordinates can be determined for any such target source, and given the (x,y,z) coordinates of three such target sources, a 6-degree-of-freedom relative position can be determined between a target member and a position measuring device according to this invention. In accordance with another aspect of the invention, the structured light image corresponding to a target source is a slightly blurry image having respective radial intensity profiles comprising the intensity values of respective sets of image pixels of the ring-shaped image feature lying along respective radial directions extending from a nominal center of the ring shaped feature. In various exemplary embodiments according to this invention, a function of a circle or an ellipse is fitted to a set of respective peaks determined for the set of respective radial intensity profiles. In various embodiments, scaling in x and y is performed to correct for magnification or image aberrations before the respective peaks are determined. In either case, the resulting fit function provides a high accuracy estimate of the size (a radial dimension) and center location of the structured light image corresponding to a target source at a sub-pixel interpolation level, and thus can be used to determine the corresponding (x,y,z) coordinates of any corresponding target source, and the resulting relative position determination with a similar high accuracy. In accordance with another aspect of the invention, a position sensing device including various elements outlined above provides images on the array detector that include at least two respective structured light image features corresponding to respective target sources, and when a separation between the position sensing device and the target member is increased, the size of each of the corresponding respective structured light image features increases on the array detector, but a spacing between respective nominal centers of the respective image features does not change on the array detector. In accordance with another aspect of the invention, the target member comprises a plurality of respective unique target source patterns usable to uniquely identify a respective region of the target member. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: FIG. 1 is an isometric view showing an exemplary structured light pattern configuration that is usable according to this invention, and an axicon lens used to generate the structured light pattern; FIG. 2 is a detailed schematic view of a first exemplary embodiment of a position sensor arrangement using a structured light target member in accordance with this invention, along with various relevant coordinate dimensions applicable to a simplified relative position determination; FIGS. 3A-3F are schematic diagrams illustrating various ring image patterns that are produced by a position sensor arrangement using a structured light target member according to this invention, for various positions of the structured light target member relative to an imaging array of the position sensor arrangement; FIG. 4 is a detailed schematic view of the first exemplary embodiment of a position sensor arrangement shown FIG. 2, viewed along the direction of the minor axis of an elliptical structured light image according to this invention, where the target member is rotated about an axis along the direction of the minor axis, along with various relevant coordinate dimensions; FIG. 5 shows an illustration of a portion of a image detector image that includes four elliptical structured light images, arranged to correspond approximately to the structured light target member and position sensor arrangement shown in FIG. 4, along with various relevant coordinate dimensions; FIG. 6 is a diagram illustrating a reference plane of a position sensor according to this invention, and a light-point plane associated with a target member, and a first exemplary set of various related position vectors; FIG. 7 is a diagram illustrating the reference plane and the light-point plane shown in FIG. 6, and a second exemplary set of various related position vectors; FIG. 8 depicts a representative image provided according to this invention, along with the results obtained from one exemplary set of image processing operations usable to identify various structured light image feature characteristics to be measured; FIG. 9 shows an exemplary structured light image feature representation similar to a result shown in FIG. 8, along with a superimposed diagram clarifying a method of determining a refined estimate of the ellipse parameters used to determine the (x,y,z) coordinates of a corresponding target source; FIG. 10 is a flow diagram of a first exemplary algorithm, for determining a relative position measurement based on a structured light image provided according to this invention; FIG. 11 is a flow diagram of a second exemplary algorithm, usable in the first exemplary algorithm, for identifying various structured light image feature characteristics in an image provided according to this invention; FIG. 12 is a flow diagram of a third exemplary algorithm, usable in the first exemplary algorithm, for determining the sizes and locations of various structured light image features in an image provided according to this invention, and the resulting target source coordinates; FIG. 13 depicts a first generic axicon lens target source configuration that is usable according to this invention, along with the resulting structured light pattern; FIG. 14 depicts the characteristics of a second generic axicon lens target source configuration that is usable according to this invention, which includes a converging lens between the light source and the axicon lens, causing adjacent rays of a structured light cone to converge at a plane to form a well-focused structured light ring image; FIGS. 15-17 illustrate views along the X-Y plane and along the Z axis, for each of three exemplary target source lens arrangements and the related structured light patterns, that are usable in various exemplary embodiments according to this invention; FIG. 18 illustrates a first exemplary illumination configuration for a structured light target member using collimated light and axicon lens target sources; FIGS. 19A and 19B illustrate a second exemplary illumination configuration for a structured light target member using light from optical fibers and axicon lens target sources; and FIG. 20 is a table comparing the characteristics of a conventional conical axicon lens and an alternative “faceted” axicon-like lens that is usable in a target source in various exemplary embodiments according to this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is an isometric view showing an exemplary structured light pattern configuration 100 that is usable in various position sensor embodiments according to this invention, including an axicon lens 115 that is used to generate a structured light cone 142. In various exemplary embodiments of a position sensor according to this invention, light propagates through a plurality of axicon lenses located on a target member, and each lens forms a structured light cone. As will be described in greater detail below, each respective structured light cone forms a ring-shaped image on a two-dimensional imaging array of the position sensor, and the image is indicative of the 3-dimensional position of the respective axicon lens that generates the structured light cone. FIG. 1 shows two representative narrow beams of light rays, 103 and 104 which form respective portions of the structured light cone 142 that is formed when the axicon lens 115 is illuminated with collimated light 110. The location and direction of the narrow beams of light rays 103 and 104 are best represented by their central rays 126 and 126′, respectively. It should be appreciated that the structured light cone 142 is actually a complete cone, in the embodiment shown in FIG. 1, consisting of a continuous distribution of light rays similar to the narrow beams of light rays 103 and 104. The structured light cone 142 has a central axis 141 and a cone angle α. The angle α is determined by the design of the axicon lens 115, as described below with reference to FIGS. 13 and 14. A hypothetical plane 145 is also shown in FIG. 1. The hypothetical plane 145 is oriented normal to the cone axis 141 and coincides with the vertex of the structured light cone 142, which is at the focal point 115′ of the light rays emitted from the axicon lens 115. Thus, the hypothetical plane 145 is also referred to as a light point plane, or target member light point plane, in the descriptions of various embodiments below. Because a target member light point plane coincides with the vertex (vertices) of the structured light cone(s) arising from the axicon lens(es) 115, or other similar target sources, it is a convenient plane for defining various coordinate relations between the location of the target sources and their corresponding structured light patterns and resulting structured light images. An exemplary light ring 143 is shown in FIG. 1 at a location where the structured light cone 142 intersects with an intersection plane that is parallel to the hypothetical plane 145, at a distance Z from the hypothetical plane 145, along a direction normal to the hypothetical plane 145. In such a case, the light ring 143 is a circle having a radius R from the cone axis 141 to the locus of points where the central rays of the structured light cone 142, such as the central ray 126, intersect with the intersection plane. In operation, the intersection plane described above is representative of the detection plane of an imaging array of a position sensor according to this invention, when the detection plane is oriented perpendicular to the cone axis 141, or equivalently, parallel to a target member light point plane represented by the hypothetical plane 145. For example, for such a configuration, when Z=Z1 the operable pixels forming the operable structured light image will be a set of pixels forming a circle of radius R1=Z1*tan α on the imaging array. If the separation between the focal point 115′ and the imaging array is then increased to Z=Z2, the operable pixels forming the operable structured light image will be a new set of pixels, forming a larger circle of radius R2=Z2*tan α. Thus, more generally, it should be appreciated that in various position sensor arrangements according to this invention, a target source (such as the axicon lens 115) that is imaged onto the imaging array of a position sensor according to this invention gives rise to a corresponding structured light image feature having a size that varies in a manner corresponding to the separation between the target source and the imaging array of the position sensor. In the presence of relative X-Y motion, the position of the nominal center of the circular structured light image corresponding to the target source will change on the imaging array. Thus, according to the foregoing description, a position sensor arrangement according to this invention can image as little as a single target source in various exemplary embodiments and provide an image on an imaging array that is usable to determine a 3-dimensional relative translational position between the single target source and the imaging array, and/or any component of that 3-dimensional relative position. FIG. 2 shows a schematic side view of a first exemplary embodiment of a position sensor arrangement 200 according to this invention, along with various relevant coordinate dimensions applicable to a simplified relative position determination. As shown in FIG. 2, the position sensor arrangement 200 includes a target member 210 including two axicon lens target sources 215 and 216, an image detector 230 (also referred to as an imaging array), and collimated light 240 from a light source (not shown.) In order to illustrate the general nature of the relationship between the size of a structured light image and a z-coordinate corresponding to that image, the relative position arrangement shown in FIG. 2 illustrates an introductory case where the target member 210 is parallel to the plane of the detectors of the image detector 230. It should be appreciated that, in practice, the plane of the detectors of the image detector 230 will generally not be parallel to the plane of the target member 210. The case of a more general relative position determination is described further below with reference to FIGS. 4 and 5. In the embodiment shown in FIG. 2, the target member 210 includes a plurality of target sources 215, 216, etc., similar to, and including, the axicon lens target sources 215 and 216, located on or in transparent portions or holes in an opaque substrate 212 formed of an opaque material or a material having an opaque coating, such that the collimated light 240 is transmitted only, or at least primarily, through the target sources. In various exemplary embodiments the plurality of target sources 215, 216, etc., are arranged in a periodic two-dimensional orthogonal array on the target member 210, with a period or pitch of Px along an axis xtm of the target member and a pitch of Py along an orthogonal axis ytm of the target member. In various exemplary embodiments, Px=Py, and both pitches may be referred to as P. Each axicon lens target source 215, 216, etc., operates in a manner analogous to the axicon lens 115, as previously described. Thus, each respective axicon lens target source 215, 216, etc., gives rise to a respective structured light cone 242, 242′ , etc., having a respective target source vertex 215′, 216′, etc., and a cone angle α that is determined by the design of the axicon lens target sources, as described elsewhere herein. A light point plane 245 is defined to coincide with the target source vertices, 215′ 216′, etc., in the same manner as previously described for the hypothetical plane 145. The respective exemplary dimensions Z215′, and Z216′, represent the separation between the respective target source vertices 215′ and 216′ on the light point plane 245 and an image detector coordinate system reference plane 224, which coincides with the plane of the detectors of the image detector 230, in various embodiments described herein. The exemplary dimensions Z215′ and Z216′ are along the z-axis direction, that is, along the direction normal to the image detector coordinate system reference plane 224. As shown in FIG. 2, the respective structured light cones 242, and 242′ are received on and imaged at the image detector coordinate system reference plane 224, where they form respective ring-shaped images that have nominal diameters d215 and d216, respectively. Along a direction in the image detector plane 224 that is parallel to the xtm-axis of the target member, the centers of the ring shaped images are separated by a dimension pccx. When the image detector coordinate system reference plane 224 and the target member 210 are parallel, as shown in FIG. 2, all the ring-shaped images are circles and all have the same nominal diameter. In general, the respective z-dimension Z corresponding to a respective target source may be determined based on the nominal diameter d of the image associated with that target source and the known cone angle α, as: Z = d 2 tan α ( Eq . 1 ) Methods for determining the nominal diameter d of a structured light image, as well as the nominal image center, are discussed further below. In the general relative position case, when the target member 210 is not parallel to the image detector coordinate system reference plane 224, the center coordinates of the structured light images produced by the light cones 242, 242′, etc., are not the x- and y-coordinates of the target source vertices 215′, 216′, etc., along the x-axis and y-axis defined by the image detector coordinate system. The geometric relationships for the general case are outlined below with reference to FIG. 4. However, for the simple relative position case shown in FIG. 2, where the target member 210 is parallel to the image detector coordinate system reference plane 224, the x- and y- coordinates of the target source vertices 215′, 216′, etc., along the x-axis and y-axis defined by the image detector coordinate system, are the same as the coordinates of the centers of the corresponding structured light images 242, 242′, etc. Thus, at least for this simple case, it should be appreciated that the three-dimensional (x,y,z) coordinates in the image detector coordinate system can be determined for each target source vertex (215′, 216′, etc.) on the light point plane 245. The more general case is described further below with reference to FIG. 4. FIGS. 3A-3F are schematic diagrams illustrating one exemplary pattern of target sources and/or target source vertices included on a target member according to this invention, and various resulting ring image patterns, viewed along the direction of the z-axis of the image detector coordinate system, that are produced by a position sensor arrangement using a structured light target member according to this invention. Each respective ring image pattern corresponds to a respective position of the structured light target member relative to the imaging array of the position sensor arrangement. As described above with reference to FIGS. 1 and 2, an axicon lens target source on the target member will produce an image that is ring-shaped at the image detector. As previously outlined, when the target member is parallel to the image detector coordinate system reference plane, that is the plane of the detectors of the image detector, the ring-shaped images are circles. However, more generally, for a conical structured light pattern, when the target member is not parallel to the plane of the detectors of the image detector, the ring-shaped image is elliptical. However, when the angle of tilt of the target member relative to the plane of the plane of the detectors of the image detector is less than approximately 25 degrees, the minor axis of the ellipse is at least 90% as large as the major axis, and the ellipse can be approximated by a circle, for purposes of illustration. FIG. 3A shows a view normal to a target member and/or light point plane as previously described. The small circles can be taken to represent target sources and/or target source vertices (also referred to as light points), arranged in pattern 300A which may be used as a target pattern for a target member according to this invention. The target source vertices are arranged according to a periodic pitch Px along an x-axis direction xtm of the target member, and a periodic pitch Py along an orthogonal y-axis direction xtm of the target member, in the embodiment shown in FIG. 3A. The pattern 300A is the basis for the exemplary images shown in FIGS. 3B-3F. The small crosses superimposed on the schematic images 300B-300F represent the approximate locations of the respective target source vertices that correspond to each respective ring-shaped structured light image, as projected along the z-axis to the plane of the detectors. In general, the dimension(s) of each respective ring-shaped image depends on the angle of tilt between the detector plane of the image detector and the target member, the operable cone angle α, and the dimension Z between the detector plane and the corresponding respective target source vertex. FIG. 3B shows an image 300B. The image 300B shows an array of ring-shaped (circular) structured light images that are formed at the image detector when the plane of the detector array is approximately parallel with the plane of the target member and/or light point plane and at some separation from the light point plane along the z-axis. FIG. 3C shows an image 300C. The image 300C shows an array of ring-shaped (elliptical) structured light images that are formed at the image detector when the light point plane is at some separation from the detector plane along the z-axis, and rotated about the ytm axis, relative to the detector plane. The sizes of the structured light images indicate that the Z dimensions/coordinates of the right-most target source vertices are greater than those of the left-most target source vertices. FIG. 3D shows an image 300D. The image 300D shows an array of ring-shaped (elliptical) structured light images that are formed at the image detector when the light point plane is at some separation from the detector plane along the z-axis, and rotated about the ytm axis, relative to the detector plane. The sizes of the structured light images indicate that the Z dimensions/coordinates of the left-most target source vertices are greater than those of the right-most target source vertices. FIG. 3E shows an image 300E. The image 300E shows an array of ring-shaped (elliptical) structured light images that are formed at the image detector when the light point plane is at some separation from the detector plane along the z-axis, and rotated about the xtm axis, relative to the detector plane. The sizes of the structured light images indicate that the Z dimensions/coordinates of the target source vertices toward the top of the image are greater than those of target source vertices toward the bottom of the image. FIG. 3F shows an image 300F. The image 300F shows an array of ring-shaped (elliptical) structured light images that are formed at the image detector when the light point plane is at some separation from the detector plane along the z-axis, and rotated about an axis 310 that is parallel to the detector plane and at an angle approximately 45 degrees counterclockwise from the xtm axis. The sizes of the structured light images indicate that the Z dimensions/coordinates of the target source vertices toward the top left corner of the image are greater than those of target source vertices toward the bottom right corner of the image. As shown in FIGS. 3C-3F, the spacing between the centers of the elliptical structured light images along the direction of the major axes of the ellipses is not the same as the spacing between the projected target source vertices (represented by the small crosses) along the direction of the major axes. In general the spacing between the centers of the ellipses along the direction of the major axes is approximately (just a very small amount greater than) the distance between the projected target source vertices along the direction of the major axes divided by the cosine of the angle of rotation (the tilt angle) between the light point plane and the detector plane about an axis parallel to the direction of the minor axes of the ellipses. However, it should be appreciated that the spacing between the centers of the ellipses is not the best indicator of relative rotation (tilt), particularly for small rotation angles. It should be appreciated that a particularly strong feature of this invention is that the size of a respective ring-shaped structured light image is a very sensitive indicator of the Z dimension/coordinate of the corresponding respective target source vertex. Thus, the various angular components of the rotation of the scale member relative to the position sensor are determined to a high degree of accuracy from these respective Z coordinates, in various exemplary embodiments according to this invention. In contrast to the previously described spacing along the direction of the major axes of the ellipses, it should be appreciated that the spacing between the centers of the elliptical structured light images along the direction of the minor axes of the ellipses is the same as the spacing between the projected target source vertices along the direction of the minor axes. It will be appreciated that this is because the minor axes are aligned along a direction where there is no angle of rotation (tilt angle) between the light point plane and the detector plane. That is the light point plane is not rotated relative to the detector plane about an axis parallel to the direction of the major axes of the ellipses. Thus, the dimension of the minor axis of an elliptical structured light image closely corresponds to the dimensions d215 and d216 shown in FIG. 2 (within approximately 1% when the rotation about the minor axis is 25 degrees), and the Z coordinate of a respective target source vertex corresponding to a respective elliptical structured light image can be accurately estimated by EQUATION 1, when the value used for d is the dimension of the minor axis of the ellipse. FIG. 4 is a detailed schematic view of the first exemplary embodiment of a position sensor arrangement 200 shown in FIG. 2, viewed along the direction of the minor axes of two elliptical structured light images according to this invention. Various relevant coordinate dimensions are shown. The various elements in FIG. 4 appear according to their projections along the viewing direction, to the plane of the figure. The approximate positions of various elements normal to the plane of the figure are indicated in FIG. 5. As shown in FIG. 4, the target member 210 is rotated about an axis parallel to the direction of the minor axes of the elliptical structured light images. Reference numbers in common with FIG. 2 denote substantially similar elements. Thus, such elements will be understood from the description of FIG. 2, and only certain additional coordinate relationships and elements not shown in FIG. 2, are described here. FIG. 4 shows that the collimated light 240 may be provided by a collimated light source arrangement 280 that is fixed in relation to the target member 210, by a schematically shown member (or members) 287. Thus, the direction of the collimated light 240 is maintained relative to the target member 210, despite rotation of the target member 210. One procedure for determining the (x,y,z) coordinates of various target source vertices 215′, 216′, etc., is now described with reference to FIGS. 4 and 5. As described previously, by determining the minor axis dimension of an elliptical structured light image, the z-coordinate for the target source vertex corresponding to that image may be closely estimated, using EQUATION 1. We assume here that the z-coordinates Z215 and Z218 have been so determined. Next, in various exemplary embodiments according to this invention, it is convenient to determine the previously described tilt about an axis parallel to the direction of the minor axes of the elliptical structured light images, which is shown in FIG. 4 by a relative rotation angle φ. Using the target source vertex 215′ and another target source vertex 218′ in the same image detector image, the rotation angle φ is equal to: ϕ = sin - 1 ( Δ Z S major ) ( Eq . 2 ) where αZ=(Z215−Z218) and the projection dimension Smajor is best understood with reference to FIGS. 4 and 5. The projection dimension Smajor is the distance between the target source vertices 215′ and 218′ along the direction on the light source plane 245 that is aligned with the direction of the major axes of the elliptical structured light images, when viewed along the z-axis. In general, as best shown in FIG. 5, the projection dimension Smajor depends on the rotation about the z-axis of the direction of the major axes (or minor axes) of the elliptical images, relative to the directions of the xtm axis and/or the Ytm axis, which are the same for the target member and the light point plane. Various known dimensions between target source vertices on the light point plane can be used to estimate a rotation angle that is, in turn, usable to estimate the projection dimension Smajor. One example is shown in FIG. 5 and described below. FIG. 5 shows an illustration of a portion of an image detector image 500 on an image detector 230. It should be appreciated that in various exemplary embodiments according to this invention, the dimensions of the image detector 230 extend beyond those shown schematically in FIG. 5. Thus, in general, such embodiments are able to simultaneously image a greater number of elliptical structured light images than are shown in FIG. 5. Accordingly, methods analogous to those described below may be applied to a larger number of elliptical structured light images, or to a set of elliptical structured light images that are spaced apart by a number of pitch increments (instead of the exemplary single pitch increment spacing described below), and such methods may provide superior reliability and/or accuracy compared to the exemplary methods described below. The image detector image 500 includes four elliptical structured light images 515, 516, 517 and 518, arranged to correspond approximately to the structured light target member and position sensor arrangement 200 shown in FIG. 4, along with various relevant coordinate dimensions. Each structured light image 5XX corresponds to the similarly numbered target source vertices 2XX′. Assuming that, based on the pixel data of the image 500, a respective best-fit ellipse has been analytically determined for each respective elliptical structured light image 5XX, each structured light image 5XX is completely characterized in terms of the image detector coordinate system. For example, the center of each ellipse (p,q)5XX, the minor axis dimension B5XX, the major axis dimension A5XX, and the angle θ between the direction of the major axes and the x-axis of the image detector coordinates is also known. Accordingly, the coordinates of all points on each ellipse can be determined according to known methods, as needed. The image detector coordinates (x,y)2XX′of each target source vertex 2XX′ are to be determined eventually, as outlined further below. In the example shown in FIG. 5, to estimate a rotation about the z-axis of the direction of the major axes (or minor axes) of the elliptical images, relative to the directions of the xtm axis and/or the Ytm axis, a rotation angle represented by β in FIG. 5 is estimated. As explained further below, the angle β estimated below is actually for an angle lying in the light point plane 245. However, the projected view along the z-axis direction in FIG. 5 is also labeled β, for simplicity. The angle β is estimated based on a dimension Lminor, that can be determined along the known direction of the minor axes in the image 500. The direction along the minor axis is chosen because the x-y plane of the image detector coordinate system is not tilted relative to the light point plane along this direction, thus, dimensions between image features along this direction are exactly the same as the dimensions between corresponding features on the light point plane along this direction. Accordingly, the dimension Lminor is determined between the known (or determinable) locations of the major axes of the elliptical structured light images (also referred to as ellipses) 516 and 518, along the known direction of the minor axes, according to known geometric methods. Since there is no tilt along the minor axis direction, as illustrated in FIG. 5, each target source vertex 2XX′ is located along the line of symmetry that coincides with the major axis and the known center of the ellipse 5XX. Therefore the determined dimension Lminor is between the major axes of the ellipses 516 and 518, and is the same as the dimension between the target source vertices 216, and 218, along the minor axis direction. It is observable from the relationship between the ellipses 515-518 in the image 500, that the ellipses 516 and 518 arise from target source vertices that are diagonal nearest-neighbors in a two dimensional array such as that described with reference to FIGS. 3A-3F. For this example, we assume the array has the same pitch P along each axis of the array. Thus, we can compare the determined dimension Lminor to the known nearest-neighbor diagonal dimension, that is, P/(tan 45 degrees), represented by the line 590 in FIG. 5, to estimate the rotation angle β. Specifically, in this example: β = cos - 1 ( L minor ( P / tan 45 ) ) ( Eq . 3 ) It should be appreciated that the dimension Lminor is an accurate dimension in the light point plane 245, because it is along the “untilted” minor axis direction in the image. Also, (P/tan 45) is an accurate known dimension in the light point plane 245. Thus, the angle β, is in the light point plane 245. If the rotation angle βwas zero, then the dimension Smajor shown in FIG. 4 would simply be P*sin(45 degrees). However, more generally, for the embodiment of the target source array on the target member 210 indicated in this description, the dimension Smajor is: Smajor=P*(sin(45+β) (Eq. 4) With reference to FIG. 4, we can now determine the relative rotation angle φ as follows. The dimension Δz shown in FIG. 4 is Δz=Z215−Z218, therefore the relative rotation angle φ may be determined as: ϕ = sin - 1 ( Δ z S major ) = sin - 1 ( Z 215 - Z 218 S major ) ( Eq . 5 ) Furthermore, as may be seen in FIG. 4, using the known cone angle α, the known dimension Z215 and the determined relative rotation angle φ, the dimension E1215 between the point PA1 and the vertex 215′, along the major axis of the ellipse 515 in the image 500, can be determined from the following general expression (with 2XX=215): E12XX=Z2XX*tan(α+φ) (Eq. 6) Thus, based on the determined dimension E1215 along the known direction of the major axis relative to the known (or determinable) image detector coordinates of the point PA1 on the ellipse 515 in the image 500, the (x,y) coordinates of the target source vertex 215′ can be determined in the image detector coordinate system, according to known geometric methods. In combination with the previously determined z-coordinate Z215, the 3-dimensional (x,y,z) coordinates of the target source vertex 215′ are fully determined. As previously outlined, if the target source vertex 215′ is translated ΔX along the x-axis or ΔY along y-axis parallel to the image detector coordinate system reference plane 224, the location of the center of the image of the ellipse 515 will translate along corresponding directions on the image detector 230. Such translations can be determined between any two successive measurement images, and accumulated over a succession of such images, as described further below. Accordingly, a position sensor arrangement according to this invention is capable of measuring the z-coordinate of the target source vertex 215′ in an absolute manner within any single image, and as well as initial (x,y) coordinates and accumulated relative X-Y motion thereafter. Accordingly, a position sensor arrangement according to this invention can determine the position of a target source vertex, such as the target source vertex 215′, along 3 translational degrees of freedom, generally denoted as X, Y, and Z degrees of freedom herein, between a target point 215′ and the position sensor arrangement. The 3-dimensional (x,y,z) coordinates of other target sources vertices, such as the vertices 216′-218′, may also be determined as described above. Based on the determined (x,y,z) positions of two target source vertices, such as the vertices 215′ and 218′, and their known spacing relative to one another on the light plane 245, the angular orientation of the light point plane 245 along a line connecting the vertices 215′ and 218′ can be determined in two planes, according to known methods. Thus, a position sensing arrangement according to this invention is capable of measuring a position relative to a target member along 3 translational degrees of freedom such as X, Y, Z and at least one angular or rotational degree of freedom, for a target member including at least two target sources having two corresponding target source vertices. Of course, with at least three target source vertices that have known (x,y,z) coordinate positions, the orientation of the light source plane 245 (and an associated target member) is completely defined. Thus, a position sensing arrangement according to this invention is capable of measuring the relative position between a position sensor having an image detector, such as the image detector 230 and a structured light target member, such as the target member 210, including 3 translational degrees of freedom such as X, Y, Z and three angular or rotational degrees of freedom. In various exemplary embodiments a signal processing unit inputs and analyzes successive structured light images arising from the target member 210 at a desired repetition rate or frame rate, in order to track accumulated motion of the target member 210, including motions that displace the target member 210 beyond one pitch increment and/or beyond one “field of view” increment along either or both directions of a two dimensional array of target sources arranged on the target member 210. In such a case, the known pitch or spacing of the target elements on the target member 210 provides a scale usable to accurately determine the total relative displacement between a position sensor according to this invention and the target member 210. One method of tracking accumulated motion along directions that lie in the image detector coordinate system reference plane 224 is an image correlation method. Various applicable correlation methods are disclosed in U.S. Pat. No. 6,642,506 to Nahum, and U.S. patent application Ser. Nos. 09/9876,162, 09/987,986, 09/860,636, 09/921,889, 09/731,671, and 09/921,711, which are incorporated herein by reference in their entirety. It should be appreciated that a position sensing arrangement according to this invention may be designed or optimized to determine a desired range of positions along the z-axis direction of the image detector coordinate system. Of course the Z-range cannot extend beyond the position where the image detector of the position sensor reaches the plane of the target source vertices. This defines Zminimum of the Z-range in various exemplary embodiments. In various exemplary embodiments, the signal processing related to analyzing the structured light target images to determine their respective (x,y,z) coordinates is simplified if the images of the various target elements do not overlap on the detector array 230. Thus, in such embodiments the minimum spacing or pitch of the target sources on the target member 210 is chosen in light of the desired Zmaximum of the Z-range and the operable cone angle α, according to the relation: minimum target source spacing>2*Zmaximum*tan α(Eq. 7) In various other exemplary embodiments, a minimum spacing is less than a value satisfying this relation and more complicated image processing is used to determine the Z-coordinates of the various target source vertices even though their respective structured light images overlap in the image detected by the image detector 230. In one exemplary embodiment, the cone angle αis approximately 15 degrees, the target sources have a diameter of approximately 100 μm, and are spaced apart by a pitch of 1.0 mm along two orthogonal axes on the target member 210. The imaging array of the image detector 230 is approximately 4.7 mm by 3.5 mm, and includes 640 columns and 480 rows of pixels arranged at a pitch of approximately 7.4 μm along the orthogonal row and column directions. The nominal operating separation from the imaging array of the image detector 230 to the light source plane 245 defined by the target source vertices is approximately 1.00 mm+/−0.5 mm. With suitable image processing, as outlined further below, such a configuration can provide a resolution and accuracy of approximately 1-8 μm for X, Y and Z translations, and approximately 0.05 degrees for roll, pitch and yaw angles. Using a suitable array detector and DSP, 6D measurements can be provided at sample rates of up to 1000 Hz or more, in various exemplary embodiments. As best seen in FIG. 5, the “image line” that forms any one of the previously described ellipses, has a nominal width along the radial direction of the ellipse. In various exemplary embodiments according to this invention, the nominal width of the elliptical image line in a particular elliptical image is determined by the design of the corresponding target source and the magnitude of the corresponding z-coordinate. It should be appreciated that the overall accuracy of a position sensor arrangement according to this invention, depends at least partly on the resolution with which the location of each portion of the “image line” that forms the previously described ellipse, or the like, can be determined. Thus, in various exemplary embodiments according to this invention, the nominal location of each portion of an “image line” is determined, fitted, or otherwise estimated with sub-pixel resolution, as described further below. Thus, in various exemplary embodiments, a position sensor arrangement according to this invention is designed such that the nominal width of the image line spans at least three pixels on the image detector 230, in order to facilitate sub-pixel interpolation for locating various image features. In various other exemplary embodiments that provide higher accuracy, the nominal width spans at fewest 3 and at most 6 pixels of the array detector 230. In other exemplary embodiments that sacrifice some accuracy and/or image processing simplicity in order to use more economical components, the nominal width spans less than three pixels or more than 6 pixels. It should be appreciated that the parameters and elements of the foregoing specific exemplary embodiments are illustrative only, and not limiting. Numerous other operable embodiments are possible, and will be apparent to one of ordinary skill in the art, having the benefit of this disclosure. As previously indicated, in various exemplary embodiments, at least three structured light images, such as the ellipses 515-518, fall within the field of view of the image detector 230 at all times. Thus, based on the (x,y,z) coordinates of the respective target source vertices corresponding to the respective structured light images, a unit vector that is normal to the light point plane 245 and the target member 210, or the like, can be found from three such target source vertices that lie on the light point plane 245. The cross-product of two vectors defined by the positions of three such target source vertices produces a vector perpendicular to the target surface, which can be used to determine various relative rotation components according to various well known methods of vector algebra and/or as outlined below. As shown in FIG. 6, the vectors ri connect the coordinate origin O on a image detector coordinate system reference plane 424, (also referred to as an image detector reference plane 424) to the target source vertices 415-417 on the light point plane 445. The vectors vi lie in the light point plane 445. The vector r0 is defined as a vector normal to the light point plane 445 that runs through the coordinate origin O. A unit vector ntm that is normal to the light point plane 445 is constructed from the cross-product of two vectors vi that lie in the light point plane 445. For the example shown in FIG. 6: n ^ tm = v 1 × v 2 v 1 × v 2 ; where v i = r i + 1 - r 1 ( Eq . 8 ) It should be appreciated that the unit vector ntm in EQUATION 8 describes the tilt of the light point plane 445 (and the associated target member) relative to the z-axis defined by the direction normal to the image detector coordinate system reference plane 424, which can be used to determine the relative angular orientation of light point plane 445 (and the associated target member) and a position sensor according to this invention, about two orthogonal reference axes, according to known methods of vector algebra. The xtm- and ytm- directions of the local x and y reference axes of the target member (and the associated light point plane 445) may be defined to coincide with a pattern of target sources arranged periodically along orthogonal axes on the target member, and/or the corresponding target sources vertices on the light point plane 445. For example, in various exemplary embodiments, the target source vertices are arranged in a periodic row and column pattern having a distance between the target source vertices in the xtm-direction and ytm-direction equal to the same periodic pitch P (that is, Px=Py=P). In various exemplary embodiments, the initial orientation of the xtm-direction and ytm-direction about the z-axis is known, and the relative rotation of the target member and light point plane 445 about the z-axis is limited to less than +/−45 degrees (or somewhat less, considering the possible effects of tilt about the x and y axes), or is tracked by a process that accumulates the net rotation about the z-axis over time. Thus, the approximate directions of the xtm and ytm axes about the z-axis are unambiguous. Accordingly, to define vectors along the xtm- or ytm- directions (assuming that tilt relative to the x and y axes is relatively limited, as is the case for most or all practical applications), in the worst case it suffices to start from the coordinates of a selected target source vertex, for example the target source vertex closest to the coordinate origin O, and identify 2 target source vertices that are closest to that one, and to each other. When the relative rotation in the X-Y plane between the target member (and/or light point plane 445) and a position sensor including an image detector, such as the image detector 230 for example, is limited to less than +/−45 degrees, or tracked, the direction of the respective vectors connecting the initially selected target source vertex with these two target source vertices will clearly identify the xtm- direction and the ytm- direction. For increased angular accuracy, longer vectors to target source vertices farther along these directions may be determined. Thus, in various exemplary embodiments, defining either of the vectors described above as v (vectors v1 or v3 in FIG. 6), unit vectors that correspond to the xtm- direction and ytm- directions are: x ^ tm = v v ( or y ^ tm = v v ) ( Eq . 9 ) The unit vector along the ztm- direction is the same as the unit vector ntm given by EQUATION 8, or is alternatively found from the cross-product: {circumflex over (z)}tm={circumflex over (x)}tm×ŷtm (Eq. 10) In various exemplary embodiments, in order to determine relative orientation and fully define a 6D measurement of relative position and orientation, a rotation matrix R is formed from the unit vectors according to well know methods of vector algebra: R = ( x ^ tm y ^ tm z ^ tm ) = ( x tm , x y tm , x z tm , x x tm , y y tm , y z tm , y x tm , z y tm , z z tm , z ) ( Eq . 11 ) where the component xtm,x of the unit vector xtm component is along the image detector coordinate system x-axis, and so on for the other subscripted vector components. The rotation matrix is also described by roll, pitch, and yaw rotations applied to the target member in the image detector coordinate system, according to known methods of vector algebra. Here it is assumed that the rotations are applied in the following sequence: first roll (θr about the x-axis), then pitch (θp about the y-axis), then yaw (θy about the z-axis). R = ( cos θ y cos θ p cos θ y sin θ p sin θ r + sin θ y cos θ r - cos θ y sin θ p cos θ r + sin θ y sin θ r - sin θ y cos θ p cos θ y cos θ r - sin θ y sin θ p sin θ r cos θ y sin θ r + sin θ y sin θ p cos θ r sin θ p - cos θ p sin θ r cos θ p cos θ r ) ( Eq . 12 ) The various rotation angles can be found by equating the two matrices. θp=θpitch=sin−1(xtm,z) (Eq. 13) θr=θroll=sin−1(ytm,z/cos(θpitch)) (Eq. 14) θy=θyaw=sin−1(xtm,y/cos(θpitch)) (Eq. 15) Alternatively, the rotation of the position sensor relative to the various axes xtm, ytm, and ztm of the target member may be determined by analogous methods of vector algebra or by known vector algebra transformations of the results indicated above. In various exemplary embodiments, the translational position of the position sensor compared to the target member may be determined as follows: The point Otm shown in FIG. 7 is defined as the current origin of the local axes of the target member. A vector that is parallel to the light point plane normal ntm, or to Ztm, between the origin O and a point that lies on the light point plane 445 defines the point Otm. As shown in FIG. 7, this is the vector r0, aligned along the Ztm axis of the light point plane 445 and connecting the two points (O and Otm) The z-coordinate of the position sensor, or “effective gap” is defined as the length of the vector r0. The current local xtm. and ytm- coordinates of the position sensor relative to the light point plane 445 (corresponding to an associated target member) will be referenced to the current light point plane origin point Otm. It should be appreciated that the 3 rotational components and the z-coordinate translational component or gap can be determined absolutely from any single target member image, as outlined above, using a position sensor arrangement according to this invention. However, it should be appreciated that the total displacements of the position sensor with respect to the light point plane 445 and/or target member along xtm- and ytm-directions are not absolute quantities, but must be determined by a process that includes tracking accumulated increments of the target source vertex pattern pitch along the xtm- and ytm-directions during relative xtm- and ytm-translation, by methods or algorithms that will be apparent to one of ordinary skill in the art. In addition, for accurate measurements, it is necessary to add to the accumulated xtm- and ytm-increments the initial position within the initial xtm- and ytm-periods of the target source vertex pattern, and the final position in the final xtm- and ytm-periods of the target source vertex pattern, in a manner analogous to well known methods used with 1D and 2D incremental optical encoders. To determine a position within the current xtm- and ytm- periods of the target source vertex pattern, the point Otm is defined by the vector r0, which is determined according to well known methods of vector algebra: r0={circumflex over (z)}tm•ri•{circumflex over (z)}tm (Eq. 16) where the vector ri can correspond to the known image detector-frame coordinates of a target source vertex, such as any of the target source vertices 415-417 shown in FIG. 7. The gap or z-coordinate is equal to the length of r0. gap=|r0| (Eq. 17) At an initial position sensor position within any current xtm- and ytm- period, the position vector lying in the light point plane 445 between the position sensor xtm- and ytm- position, which coincides with point Otm, and any one or more target source vertices associated with nearby ring-shaped structured light source images in the image detector image, may be determined as: ui=ri−r0 (Eq.18) To determine the coordinates of the position sensor in terms of the current target member coordinates: xi=ui•{circumflex over (x)}tm (Eq. 19) yi=ui•ŷtm (Eq. 20) where xi and yi are the current local displacements of the position sensor from the nearby target source vertex corresponding to the particular position vector ui used in EQUATIONS 19 and 20, along the current xtm- and ytm- axes. As previously described, it is possible and necessary to track the accumulated increments of the xtm- and ytm- pitch of the target source vertex pattern between an initial or reference position and a current or final position. Thus, the accumulated increments between the reference target source vertex used for an initial position determined according to EQUATIONS 18-20, and the reference target source vertex used for a final position determined according to EQUATIONS 18-20, are known or can be determined. Thus, the current x-y position (that is, the accumulated x-y displacement) of the position sensor relative to the light point plane 445 and/or target member can be determined accordingly. The foregoing procedures outline one exemplary set of procedures for determining the coordinates of various target source vertices, and the 6D relative position between a light point plane (and/or target member) and a position sensor according to this invention. It should be appreciated from the foregoing procedures that, more generally, given the determination of the coordinates of 3 target source vertices relative to a position sensor according to this invention, any ID to 6D relative position measurement between the light point plane (and/or target member) and the position sensor according to this invention can be determined with reference to any coordinate frame that is appropriate or convenient for a particular measuring application. Any alternative mathematical method and/or signal processing may be used that is appropriate or convenient in a particular application. For example, in various motion control applications, it may be convenient to roughly determine various accumulated displacements based on stepper motor control signals or the like. In such a case, yaw rotations and incremental target source vertex pattern pitch accumulations need not be restricted or tracked, and it may be sufficient to simply determine various current local positions as outlined above, in order to refine the rough displacement determinations based on the stepper motor control signals, or the like, to a higher accuracy level. Furthermore, it should be appreciated that for any particular image detector image, various combinations of target source vertices may be used to provide redundant measurements, which may be averaged to enhance the measurement accuracy in various exemplary embodiments according to this invention. Accordingly, the foregoing exemplary procedures are illustrative only, and not limiting. The previous discussions have not considered in detail the width, and the intensity variation radially across the width, of the lines that form the elliptical structured light image features in an image provided according to this invention. FIG. 8 depicts a representative image 800-A that is provided according to this invention. FIG. 8 also depicts results obtained from one exemplary set of image processing operations usable to identify various structured light image feature characteristics in a measurement image according to this invention, as demonstrated on the image 800-A. The pseudo-image 800-B1 is produced by determining an intensity threshold, for example an intensity value between the peaks of a bimodal intensity distribution determined from the image 800-A, and assigning all pixels having intensities below the threshold a value of zero, and all other pixels a value of one. The pseudo-image 800-B2 shows a close-up of one of the ring-shaped features that results from applying a filter to smooth the boundaries in the pseudo-image 800-B1. For example the filter may comprise setting each pixel value to the value of the majority of its 8-connected neighbors. The pseudo-image 800-B3 shows a close-up of the ring-shaped feature of the pseudo-image 800-B3 that results from applying a further boundary smoothing operation. For example, the further smoothing operation may comprise a first dilation operation wherein each pixel is assigned the value corresponding to the maximum pixel value (1, for a binary image) in its 8-connected neighborhood, followed by a second erosion operation wherein each pixel is assigned the value corresponding to the minimum pixel value (0, for a binary image) in its 8-connected neighborhood. The pseudo-image 800-B4 shows a pseudo-image of the result obtained by retaining only an approximately single-pixel-wide track at the inner and outer boundaries of all ring-shaped structured light image features processed similarly to the ring shown in the close-up view 800-B3. In one exemplary embodiment, a first connectivity analysis is performed to identify the pixels corresponding to each individual ring-shaped structured light image feature. For example, in one exemplary embodiment, starting a set from any one-valued pixel, each neighboring one-valued pixel is added to the set. Then each of the one-valued neighbors of each of the added pixels is added to the set, and so on, until there are no new one-valued neighbors to add. Then that set of pixels is labeled as an individual ring-shaped structured light image feature. The process is repeated until all desired ring-shaped features are identified and labeled. Each ring-shaped structured light image feature is “labeled” or identified so that the appropriate pixels are used for the fitting routine(s) to be applied later to each ring-shaped image feature, as described further below. Next, in various embodiments, each labeled feature is processed to determine an approximately single-pixel-wide track at its inner and outer boundaries. For example, for a labeled feature, a subset of its one-valued pixels is identified corresponding to those pixels that have a neighbor that has a value of zero. Then, a connectivity analysis is performed on the subset. Two further subsets will result: The connected pixels forming a ring at the outer boundary of that labeled feature, and the connected pixels forming a ring at the inner boundary of that labeled feature. Such labeled subsets are shown in the pseudo-image 800-B4. The pseudo-image 800-C1 shows a close-up of the circular tracks of one of the ring-shaped features in the pseudo-image 800-B4, and the pseudo-image 800-C2 shows best-fit dashed-line ellipses 810 and 820 fit to the elliptical tracks of the ring-shaped feature of the pseudo-image 800-C1. The elliptical tracks of each ring-shaped image feature in the pseudo-image 800-B4 may be similarly processed, using any now known or later developed ellipse fitting method. One exemplary ellipse fitting method that is usable in various embodiments according to this invention is described in “Image Fusion and Subpixel Parameter Estimation for Automated Optical Inspection of Electronic Components”, by James M. Reed and Seth Hutchinson, in IEEE Transactions on Industrial Electronics, Vol. 43, No. 3, June 1996, pp. 346-354, which is incorporated herein by reference in its entirety. The ellipse fitting method described in the reference cited above can use the pixel data of the identified elliptical image features described above to provide values for the major and minor axis dimensions A, B, and the orientation angle θ (shown in FIG. 5, for example), as well as x and y center coordinates, which are referred to as the (p,q) center coordinates in FIG. 5. In various exemplary embodiments according to this invention, the average of the minor axis dimensions of the inner and outer ellipses is used as the dimension d in EQUATION 1. More generally, each of the respective ellipse parameters characterizing the inner and outer ellipses are respectively averaged, and the average parameters are used to characterize the corresponding elliptical structured light image. For example, in addition to determining the z-coordinate, the averaged parameters are used to determine the coordinates of the point PA1 (see FIG. 5), or the like, that is used along with the dimension E12XX determined according to EQUATION 6, to determine the (x,y) coordinates of the corresponding target source vertex. Thus, in various exemplary embodiments the (x,y,z) coordinates of a target source vertex are determined using the corresponding fit ellipse(s) resulting from the operations described above with reference to FIG. 8, or the like. In cases where N points are inscribed along a circle or ellipse (see FIG. 20 and the related description), the centroid of each point could be found by any one of several known methods, such as an intensity weighted “center of mass” type calculation for all pixels over a given threshold in intensity. Once the point locations are known, they can be fitted to an equation for an ellipse by standard fitting methods. It should be appreciated that the image processing operations described above are illustrative only, and not limiting. Various operations may be eliminated, replaced by alternative operations, or performed in a different sequence, in various embodiments according to this invention. It should be appreciated that while the foregoing image processing and coordinate determining operations are relatively fast, and provide sufficient accuracy for a number of applications, the image processing operations have suppressed a considerable amount of the information available in the original image of each ring shaped feature. It should be appreciated that the estimated coordinates of each target source vertex can be determined with higher accuracy, or refined, by making use of this suppressed information. FIG. 9 shows an illustration 900 of the best-fit ellipses 810 and 820 and the elliptical tracks of the image 800-C2 of FIG. 8, along with a superimposed diagram clarifying one exemplary method of determining a refined estimate of the parameters of an ellipse used to determine the (x,y,z) coordinates of a corresponding target source vertex in various exemplary embodiments according to this invention. Briefly, at least two lines 910A and 910B are drawn through the averaged center of the best-fit ellipses 810 and 820, such that the lines are approximately evenly spaced over 360 degrees around the best-fit ellipses 810 and 820. It is desirable that two such lines are aligned along the estimated minor and major axes of the best-fit ellipses 810 and 820, particularly if only a few of the lines 910X are drawn. Next the respective sets of pixels that are closest to the respective lines 910A and 910B and that lie between the best-fit ellipses 810 and 820 are identified. For each respective set of pixels, the corresponding intensity values in the original target member image are determined, as indicated by the respective radially-oriented intensity profiles 920A-920D. Next, the respective pixels 930A-930D corresponding to the respective peaks of each of the radially-oriented intensity profiles 920A-920D are identified by any now known or later developed method. For example, in various embodiments a curve or a specific experimentally determined function is fit to the respective radially-oriented intensity profiles, the respective peaks of the set of curves or functions are determined according to known methods, and the corresponding set of respective pixels 930A-930D is identified. Next, a new best-fit ellipse is fit to the set of respective “peak pixels” 930A-930D according to any now known or later developed method that provides high accuracy, such as those that include outlier removal and the like. Next, the ellipse parameters of that new best fit ellipse are used to determine the (x,y,z) coordinates of the corresponding target source vertex, as previously described, in order to provide a more accurate refined estimate of the (x,y,z) coordinates of a target source vertex in various exemplary embodiments according to this invention. It will be appreciated that although FIG. 9, for simplicity, shows two lines that are used as the basis for defining 4 data points that are fit to a ellipse, a greater number of lines and associated data points will generally provide higher accuracy, and are therefore desirable in various exemplary embodiments according to this invention. More generally, the methods and operations outlined above with respect to FIGS. 8 and 9 are illustrative only and not limiting. A variety of alternative image processing operations may be used to locate the elliptical image features and determine the desired target source vertex coordinates. Descriptions of the image processing operations outlined above, as well as numerous alternatives, may be found in image processing literature, for example in Machine Vision, by Ramesh Jain, et al., McGraw Hill, 1995, which is incorporated herein by reference in its entirety. FIG. 10 is a flow diagram of a first exemplary algorithm 1000, for determining a relative position measurement between a position sensor and light point plane and/or target member based on an image provided according to this invention. The algorithm begins at a block 1100 with acquiring an image including a plurality of structured light image features. At a block 1200, operations are performed to find at least some of the plurality of structured light image features, such as the previously described elliptical image features, in the image acquired at the block 1100. Next, at a block 1300, operations are performed to determine the characteristics of the structured light images found at the block 1200, such as the previously described ellipse parameters, and to determine the resulting coordinates for a desired number of corresponding target source vertices. The algorithm continues to a block 1400, where operations are performed to determine the relative position between the position sensor and light point plane and/or target member for 1 to 6 degrees of freedom in a desired coordinate system, based on the target source vertex coordinates determined at the block 1300. FIG. 11 is a flow diagram of a second exemplary algorithm 1200′, which is one exemplary embodiment usable for the operations of the block 1200 of the first exemplary algorithm, for identifying various structured light image feature characteristics in an image provided according to this invention. The algorithm begins at a block 1210 by converting an acquired image according to this invention to a binary-valued pseudo-image, based on a default or specifically determined intensity threshold. At a block 1220, image processing operations are performed to isolate or identify desired structured light image feature characteristics in the binary image. In one exemplary embodiment, the operations of the block 1220 apply one or more known image filtering operations to smooth the boundaries between the zero-valued (dark) pixels and the one-valued (light) pixels in the pseudo-image data and identifying pixels corresponding to two elliptical single-pixel-wide tracks at the smoothed boundaries. The two tracks are preferably either both all-dark or both all-light pixels. The two elliptical single-pixel-wide tracks provide structured light image feature pixel sets corresponding to elliptical structured light image feature characteristics that are associated with a corresponding target source vertex. Next, at a block 1230, operations are performed to effectively identify or label the desired structured light image feature pixel sets that are to be associated with each corresponding target source vertex. Next, in various exemplary embodiments according to this invention, at a block 1240 operations are performed to screen or validate the structured light image feature pixel sets identified at block 1230, in order to eliminate pixel sets that pose a risk of providing degraded or invalid coordinates for a corresponding target source vertex. In various exemplary embodiments the operations of block 1240 may comprise one or more of a pixel connectivity test indicative of sufficiently well-defined target features, a pixel outlier test based on an expected shape to be exhibited by a valid set of pixels, a test based on the proximity of adjacent pixel sets (which may indicate a potential distortion due to the overlap or proximity of adjacent structured light image features near the ends of the measuring range in various exemplary embodiments), and/or any other now known or later developed test that serves the purpose of the block 1240. However, in various exemplary embodiments according to this invention where sufficiently reliable structured light image features and/or sufficiently accurate measurement results are otherwise insured, the operations of the block 1240 may be omitted. FIG. 12 is a flow diagram of a third exemplary algorithm 1300′, which is one exemplary embodiment usable for the operations of the block 1300 of the first exemplary algorithm, for determining the structured light image characteristics of various structured light image features in an image provided according to this invention, and the resulting coordinates for a desired number of corresponding target source vertices. The algorithm begins at a block 1310 by determining an initial estimate of the average ellipse parameters of a structured light image feature based on a first selected pixel set that is known or presumed to be a set of pixels usable to provide sufficiently accurate coordinates for a corresponding target source vertex. The average ellipse parameters of the structured light image feature may be determined according to any suitable now known or later developed method. In various exemplary embodiments, the selected valid pixel set is provided by the results of the algorithm 1200′. In one exemplary embodiment, the results of the algorithm 1200′ provide two concentric elliptical single-pixel-wide tracks which characterize the structured light image feature and the parameters characterizing of the corresponding structured light image feature are determined based on the averaged parameters of best-fit ellipses that are fit to the two elliptical single-pixel-wide tracks according to any known method. Next, in various exemplary embodiments, at a block 1320 operations are performed to refine the initial estimates of the ellipse parameters provided by the operation of the block 1310. The refined estimates are usable to determine the (x,y,z) coordinates of a corresponding target source vertex to a higher level of accuracy than that provided by the initial estimates. The refined estimates may be determined according to any suitable now known or later developed method. In one exemplary embodiment, the operations of the block 1320 comprise determining a plurality of lines or vectors extending through the initially estimated ellipse center and past the extremities of the corresponding selected pixel set. The lines are evenly spaced over 360 degrees about the initially estimated ellipse center. It is preferable that two of the lines extend along the minor and major axes of the initially estimated ellipse. Next, operations are performed to identify respective sets of radially arranged pixel addresses that are closest to the respective lines, and that lie between the inner and outer boundaries corresponding to the structured light image feature in the corresponding selected pixel set. Next, for each respective set of radially arranged pixel addresses, the corresponding intensity values in the original image are determined. Next, the pixel addresses or image detector coordinates are determined that correspond to the respective nominal peak intensity locations for each of the respective sets of radially arranged pixel addresses. For example, in various embodiments a curve or a specific experimentally determined function is fit to the respective radially arranged intensity values, the respective peaks of the set of curves or functions are determined according to known methods, and the corresponding pixel addresses or image detector coordinates are determined. Next, a best-fit ellipse is fit to the set of respective “peak pixels” according to any now known or later developed method, and the resulting ellipse parameters constitute the refined estimate provided at the block 1320. When the operations of the block 1320 are completed, operation passes to the block 1330. It should be appreciated that in various exemplary embodiments or applications of the algorithm 1300′, the initial ellipse parameter estimates provided by the operations of the block 1310 are usable to identify the coordinates of the corresponding target source vertex with sufficient accuracy for that embodiment of application. In such cases, the operations of the block 1320 are omitted. In such cases, operation passes directly form the block 1310 to the block 1330. At the block 1330, the (x,y,z) coordinates of the corresponding target source vertex are determined based on the current estimated target feature ellipse parameters, by any now known or later developed method. The methods previously described herein are used in various exemplary embodiments. Next at a decision block 1340, if there are more selected structured light image feature pixels set to analyze, the algorithm returns to operations at the block 1310. Otherwise, if there are no more selected structured light image feature pixels set to analyze, the algorithm continues to a block 1350, where operations are performed to store the all the target source vertex (x,y,z) coordinates previously determined by the algorithm 1300′. FIG. 13 shows a detailed schematic side view of an exemplary conical axicon lens target source configuration 600 and the resulting structured light pattern. The relationship between Z and d in FIG. 13 has been previously discussed and is given by EQUATION 1. The axicon lens 615 shown in FIG. 13 is cylindrically symmetrical about the optical axis 641 and the conical portion of the lens has a base angle φ. The conical portion of the lens causes the rays of an incident collimated beam 640 to refract towards the optical axis 641, according to a refraction angle α. The refraction angle α is designed or determined as follows: α=(n =1)φ (Eq. 21) where f is the base angle and n is the index of refraction of the lens material. The refraction angle α is effectively the same as the cone angle α previously described herein. The central rays 626 and 626′ represent the nominal path of the wall(s) of the structured light cone 642, which has a nominal thickness or width that gives rise to a nominal image line thickness W in the structured light images arising from the light cone 642. In general, a position sensor arrangement according to this invention can be more accurate when the axicon lens 615 and collimated beam 640 are configured to produce an image line thickness W that is within a range to span approximately 3-6 pixels on an image detector of the position sensor arrangement. Such a range tends to define the image line location with high resolution, while also providing an image line that is wide enough to facilitate accurate image dimension measurement when using subpixel interpolation to estimate the image line's nominal (center) location with high resolution. However, both narrower and much wider nominal image line widths are also operable and, possibly, more robust or more economical in various applications of various exemplary embodiments according to this invention. As can be seen in FIG. 13, in various exemplary embodiments according to this invention, the image line width W is primarily controlled by the choice of the lens radius R and the cone angle (refraction angle) α. However, the cone angle α is generally constrained by other design considerations, so the lens radius becomes the primary means of controlling the image line width W in various embodiments. For ideally collimated light and a precise axicon lens, image line width W is approximately: W =R*(1−tan φ tan α) (Eq. 22) As one design example, in one embodiment a cone angle of 20 degrees is to be provided using an axicon lens material having a refractive index of 1.5. For this case, from EQUATION 21, α=40 degrees, thus, (1- tan φ tan α)≈0.75. If the image detector pixel pitch is approximately 7 microns and an image line width of approximately 6 pixels =42 microns is desired, then from EQUATION 22, R=56 microns. R can alternatively be controlled by an aperture on either side of the axicon lens 615, or by otherwise controlling a beam radius of the collimated light 640. However, if either of these techniques results in illumination that is not concentric with the optical axis 641, then the image line width around the resulting structured light image will be asymmetric, and this asymmetry may also vary for various lenses arranged on a target member, which may lead to systematic errors. Thus, in various exemplary embodiments it is more convenient and consistent for the collimated light 640 to overfill the axicon lens 615, which can economically provide the desired line width symmetry, and reduce or eliminate the need for special alignment or assembly procedures. The paths of the central rays 626 and 626′ converge to, and diverge from, a point referred to herein as the target source vertex 615′, because it is the nominal vertex of the structured light cone 642. The target source vertex 615′ is spaced apart from the lens vertex 608 by a distance f along the optical axis 641. For an overfilled lens of radius R: f = R 2 * ( 1 - tan φ tan α ) ( Eq . 23 ) FIG. 14 shows a schematic side view of a second exemplary axicon lens target source configuration 700 that is usable according to this invention. The target source configuration 700 includes various elements and operating principles which are similar to the target source configuration 600 described above. Elements numbered 7XX in FIG. 14 will be understood to be similar in function to the similarly numbered elements 6XX in FIG. 13, unless otherwise indicated. Due to the basic similarities in design and operation between the target source configurations 600 and 700, only the varying aspects of the target source configuration 700 that require additional explanation are described below. It should be appreciated that the vertical and horizontal dimensions of FIG. 14 are not drawn to scale. In particular, the focal length F may be chosen to be much longer than its apparent representation in FIG. 14. The target source configuration 700 includes a composite target source 715 that includes a converging lens 713 that receives the collimated light 740 and directs slightly converging rays to a “matching” axicon lens 714. Thus, the composite target source 715 is designed such that adjacent rays of the structured light cone 742′ converge at a focal plane 750 at a distance from the composite target source 715. As a design guideline, the distance from the converging lens 713 to the focal plane 750 is roughly the same as the focal length of the converging lens 713, even though the axicon lens 714 has been introduced into the optical path. Additional design considerations for such a lens system, including various beneficial modifications that may be added near the vertex 708 of the axicon lens 714, are described in detail in the article “Characterization And Modeling Of The Hollow Beam Produced By A Real Conical Lens”, by Benoit De'pret, et. al., Optical Communications, 211, pp. 31-38, October, 2002, which is incorporated herein by reference. Therefore, additional design and operating aspects of the target source configuration 700 need not be discussed here. The essential point of the target source configuration 700 is simply that it provides one means of compensating for undesirable divergence of the wall(s) of a structured light cone according to this invention, and the resulting blurring and/or width increase of the image lines that may otherwise occur for values of Z near the maximum range of a position sensor. (The target source configuration 600 shown in FIG. 13, provides one example where this might occur, due to practical fabrication imperfections, for example.) In one exemplary embodiment, the design location for the focal plane 750 is beyond the desired maximum Z-range, such that the theoretical minimum image line width within the maximum Z range corresponds to approximately 3-6 pixels on the image detector of the position sensor. In another embodiment, the design location for the focal plane 750 is within the Z-range. In such an embodiment, a narrower image line width remains operable within the expected Z range, and/or imperfect collimation, optical aberration, or various other potential “blurring” effects provide a “cone wall beam waist” that provides a desirable minimum image line width. Of course, various other lens configurations can provide the same function as the composite target source 715, such as a single “slightly convex axicon”, or the like. Such lens configurations can be determined by one skilled in the art and developed by analytical design and/or experimentation. FIGS. 15-17 show three exemplary target source configurations and various aspects of the resulting structured light patterns. FIG. 15 shows a schematic side view of a target source configuration 1500 that is functionally the same as the target source configuration 600, except that two adjacent axicon lenses 1515 and 1516 are shown on a portion of a target member 1510, to indicate the relationship between the adjacent structured light cones 1542 and 1542′. An image detector 1530 is also shown. The axicon lenses 1515 and 1516 are shown in the upper side view illustration, and also in a top view illustration where they are numbered 1515TOP and 1516TOP, respectively. The configuration shown in FIG. 15 is essentially the same as that described with reference to FIGS. 2-5 above, and is shown here primarily for convenient comparison to the following descriptions of FIGS. 16 and 17. FIG. 15 shows a maximum range ZMAX, which corresponds to the range where the structured light cones 1542 and 1542′ do not overlap. This consideration has been previously discussed with reference to EQUATION 7. FIG. 16 shows a schematic side view of a target source configuration 1600. Where a subscript “TOP” is added to any reference number in FIG. 16, it will be understood that the element referred to is shown from a top view. Non-subscripted reference numbers are used for the side view of the same elements. The target source configuration 1600 includes a ring-shaped target source 1615 that produces a structured light pattern 1642, that may be described as a pair of structured light cones, one inverted and one not, with a common vertex at the plane 1622. Thus, the use of the structured light pattern 1642 to determine the (x,y,z) coordinates will be understood by one skilled in the art, having benefit of this disclosure. For example, the plane 1622 is analogous to the light point plane(s) previously described herein, including the target source vertices, which define that plane. However, in this case, both “positive” and “negative” Z values may be determined for the light point plane 1622. The advantage of this configuration 1600 is that the maximum Z range where adjacent structure light patterns do not overlap is doubled in comparison to the similar maximum Z range of the configuration 1500. Of course, for this configuration 1600 there will be a position ambiguity for +/−z-coordinates (about the light point plane 1622) which are of the same magnitude, such as the pair of planes 1621 and 1623. In various exemplary embodiments, this potential ambiguity is resolved by one of various possible means at the level of the system that hosts, or uses, a position sensor that incorporates the target source configuration 1600. For example, started from a known initial position, the relative motion between the target member 1610 and the image detector 1630 may be tracked or accumulated, or the motion control signals used to provide the relative motion may be analyzed, or both, in order to distinguish between potential ambiguous positions. Regarding the ring-shaped target source 1615, it has a nominal diameter D, and a cross-section that is identical to that of half of an axicon lens, in order to provide the cone angle α. Thus, the angle used for the ring-shaped lens of the target source 1615 may be designed and/or determined essentially as previously described with reference to FIG. 13 and EQUATIONS 21-23. Portions of the surface of the target member 1610 other than the ring-shaped lens(es) of the target source 1615 and the like, are made opaque by any convenient means. In one embodiment, the target member 1610 includes a film pattern that passes collimated light through ring-shaped pattern openings that effectively define the width of the wall(s) of the structured light pattern 1642, and the like. That is, the thin film pattern transmits light through pattern openings that under-fill the ring-shaped lenses that form the ring-shaped target sources 1615. The lenses may be formed concentrically with the ring-shaped openings by any convenient means, for example, by applying preformed lenses, by micro-molding lenses in place, by micro-embossing a polymer coating, or any other suitable now known or later-developed method. It should be appreciated that when the aforementioned thin film pattern (or the like) is used, that excess material outside of the region of the light-transmitting openings, and outside of the lens regions, has no deleterious effect. FIG. 16 also shows portions of similar adjacent ring-shaped target sources 1616-1619, along with portions of adjacent structured light patterns 1642′ and 1642″, corresponding to target sources 1616 and 1617, respectively. Thus, such ring-shaped lenses form a corresponding array on the target member 1610 in various exemplary embodiments according to this invention. FIG. 17 shows a schematic side view of a target source configuration 1700 that provides an extended Z range similar to that provided by the target source configuration 1600. However, the target source configuration 1700 uses an arrangement of lenses that provide structured light patterns that can provide unambiguous z-coordinate determinations throughout the entire Z range. Where a subscript “TOP” is added to any reference number in FIG. 17, it will be understood that the element referred to is shown from a top view. Non-subscripted reference numbers are used for the side view of the same elements. The target source configuration 1700 includes concentric ring-shaped target sources 1715B and 1715C that produce structured light patterns 1742′ and 1742″. The structured light pattern 1742′ is similar to the structured light pattern 1642 described with reference to FIG. 16. The structured light pattern 1742″ is an inverted cone. The target source configuration 1700 also includes a concentric axicon lens 1715A, that produces the structured light pattern 1742, which is similar to the structured light pattern 1542 described with reference to FIG. 15. All lenses, and the target member 1710 overall, may be fabricated in a manner analogous to previous descriptions for similar elements. As shown in FIG. 17, the target source 1715B has a nominal radius r and the target source 1715C has a nominal radius of 2.5r. This configuration assures that for any separation Z between the target member 1710 and the image detector 1730, a structured light image will be provided that has a configuration of “nested” ellipses that have a unique size relationship that is specific to that Z value. It is possible to construct an algorithm which completely describes the correlation between the ellipse parameters and Z. For example, consider the illustrated case where a pattern of “circular ellipse” light rings are provided at the set of hypothetical planes A to H. To determine which lens on the target member 1710 is causing each light ring, the radii of the light rings are compared. On planes A to B, the distance between the outer two light rings is equal to r, and there is also an inner ring. On planes B to D, the distance between the innermost and outermost light rings is equal to r. On planes H to G, the distance between the innermost and outermost light rings is equal to 1.5.r and there is also an inner ring. On planes G to E, the distance between the innermost and outermost light rings is equal to 1.5r. On planes E to D, the distance between the inner two light rings is equal to r, and there is also an outer ring. Thus, it is apparent that each plane has a unique decipherable ring configuration. Of course, the size of each respective light ring either increases or decreases in a known manner in proportion to Z. Thus, Z may be determined with high accuracy and resolution as previously described herein, and without ambiguity, over the entire Z range. In application, the light rings in the images will typically be ellipses, as previously described herein. However, in such cases, certain parameters of the ellipses in each nested set of ellipses will have relationships analogous to the relationships between radii discussed above. For example, the minor axes of the ellipses will behave very similarly over a reasonable range of tilt angles. Thus, relationships based on determined ellipse parameters, or combinations of determined ellipse parameters can be used to determine Z values, without ambiguity, over the entire Z range. FIG. 17 also shows portions of similar adjacent ring-shaped target sources 1716-1719. Thus, such ring-shaped lenses form a corresponding array on the target member 1710 in various exemplary embodiments according to this invention. FIG. 18 illustrates one exemplary illumination configuration for a portion of a structured light target member 1810 usable according to this invention. The target member 1810 is illuminated by collimated light 1840 that illuminates at least the portion of the target member 1810 that is imaged onto a position sensor image detector, or the entire target member 1810. The use and production of collimated light is well known, and the collimated light 1840 may be provided according to any now known or later developed method, provided that the collimated light remains aligned in a fixed relationship along, or nearly along, the optical axis of the axicon lenses, regardless of any motion of the target member 1810. In the embodiment shown in FIG. 18, the axicon lens target sources 1815 and 1816 are located on a transparent substrate 1811, which may be, for example, borosilicate glass having a thickness of approximately 1-3 mm or more, depending on the overall size of the target member 1810 and the required mechanical strength and stiffness in a particular application. Except for the area coinciding with the axicon lens target sources 1815 and 1816, the surface of the transparent substrate 1811 that carries the lenses is covered with an opaque coating. In one embodiment the coating is a thin film coating, as previously described with reference to FIG. 16. FIG. 19A and 19B illustrate another exemplary illumination configuration for a portion of a structured light target member 1910 usable according to this invention. As best seen in the less detailed FIG. 19A, representative respective axicon lens target sources 1915 and 1916 abut the ends of respective gradient index lenses 1982 and 1983. The respective gradient index lenses 1982 and 1983 abut, and receive light from, respective single-mode optical fibers 1980 and 1981, which receive light (meaning any operable spectrum or wavelength of light detectable by a corresponding image detector) from a light source (not shown) that is located at any convenient position. The characteristics of the gradient index lenses 1982 and 1983 and the single-mode optical fibers 1980 and 1981 are selected by analysis and/or experiment to provide collimated light to the axicon lens target sources 1915 and 1916. The optical fibers, gradient index lenses, and axicon lens target sources may be assembled by any now known or later developed method. For example by methods commonly used in the telecommunications industry. In one embodiment, holes are fabricated in the substrate 1911 with precise tolerances, and the various optical components are inserted and aligned in the holes and fixed in position by suitable optical grade adhesives. FIG. 19B shows a magnified portion of the target member 1910, and shows both the core 1980A and the cladding 1980B of the single mode fiber 1980. FIG. 20 is a table comparing the characteristics of a conventional conical axicon lens and an alternative faceted “axicon-like” lens that is usable in a target source in various exemplary embodiments according to this invention. The conventional axicon lens is shown in column 20-A. Along that column, cell R-1 shows the conventional axicon lens, cell R-2 shows a circular structured light image that is provided by the conventional axicon lens when the image plane is normal to the optical axis of the lens, and cell R-3 shows an elliptical structured light image that is provided by the conventional axicon lens when the image plane is angled relative to the optical axis of the lens. One exemplary embodiment of an alternative faceted “axicon-like” lens is shown in column 20-B. In order to illustrate the operation of such a lens, it is assumed to be fabricated with a facet base angle that is the same as the axicon base angle of the lens shown in column 20-A. Along the column 20-B, cell R-1 shows the faceted “axicon-like” lens, which has 6 faces in this embodiment. For comparison, cell R-2 of column 20-B reproduces the circular structured light image that is provided by the conventional axicon lens and shown in cell (R-2,20-A) in dashed outline, and superimposes the “discrete” structured light image provided by the faceted lens. As can be seen in that cell R-2, the faceted lens provides 6 discrete light spots, that are nominally individual triangles corresponding to the 6 facets of the faceted lens. When both of the lenses along row R-1 have approximately the same radial dimension, and the same base angle, the discrete structured light image spots provided by the faceted lens will form image patterns that coincide with the shape and image line width of the previously described continuous images of the corresponding conventional axicon lens. Cell R-3 of column 20-B shows an elliptical pattern of discrete structured light image spots that is provided by the faceted axicon-like lens when the image plane is angled relative to the optical axis of the lens, along with a superimposed outline of the image from the corresponding convention axicon lens. In general a faceted lens concentrated the source illumination to provide discrete spots that have a relatively high intensity. It should be appreciated, that using suitable pattern recognition algorithms, such patterns of discrete spots can be recognized. Then ellipses can be fit to them, in a manner analogous to that previously described for the elliptical images provided by the conventional axicon lens. In general 6 or more facets are desirable, and more facets are preferred for higher accuracy and easier pattern recognition. It should appreciated that it is the structured light pattern that is provided, not a particular lens type, that is crucial to this invention. Accordingly, any operable refractive type lens can be replaced by any other functionally equivalent element. Such elements include, but are not limited to, various types of diffractive optical element (DOE) lenses, including Fresnel lenses, and the like. DOE lenses, including Fresnel lenses, and the like, may be designed and fabricated according to known methods, and may be manufactured as an array on a single substrate, if desired. Custom designed and fabricated DOE lenses, Fresnel lenses, and/or arrays are available from various sources, for example, Digital Optics Corporation, 9815 David Taylor Drive, Charlotte, N.C., USA. DOE lens design techniques are also described in MICRO-OPTICS: Elements, Systems and Applications, Edited by Hans Peter Herzig. Taylor & Francis, London, 1970, and Methods for Computer Design of Diffractive Optical Elements, Edited by Victor A. Soifer. Wiley-Interscience; John Wiley and Sons, Inc., New York, 2002, which are incorporated herein by reference. While this invention has been described in conjunction with the exemplary embodiments and configurations outlined above, it is evident that the embodiments and configurations described above are indicative of additional alternative embodiments, configurations, and combinations of design parameter values, as will be apparent to those skilled in the art having benefit of this disclosure. Accordingly, the embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>Various accurate 2-dimensional (2D) optical position sensing systems are known. For example, one 2D incremental position sensor using a 2D grating scale and providing high resolution and high accuracy for sensing translation in an X-Y plane is disclosed in U.S. Pat. No. 5,104,225 to Masreliez, which is incorporated herein by reference in its entirety. Such a system is essentially an orthogonal combination of well known 1-dimensional (1D) optical encoder “incremental” measurement techniques that sense the position of a readhead within a particular period of a periodic scale grating for high resolution and continuously increment and decrement a count of the number of periods of the periodic scale that are traversed during a series of movements, in order to continuously provide a net relative displacement between the readhead and scale. However, such systems cannot sense the “z-axis” separation between a readhead and scale. A very limited number of types of optical position sensors capable of sensing more than two degrees of freedom of a relative position of an object are known. One system comprising a probe that can sense relative position for up to 6 degrees of freedom is disclosed in U.S. Pat. No. 5,452,838 to Danielian and Neuberger. The '838 patent discloses a probe using a fiber optic bundle, with individual fibers or sets of fibers acting as individual intensity sensing channels. The individual intensity signals vary with X-Y motion of an illuminated target surface, as well as with the proximity of each fiber to the illuminated target surface along a direction normal to the surface. However, the probe disclosed in the '838 patent provides relatively crude measurement resolution and a limited sensing range for “z-axis” separation and orientation between the probe and a target surface. Known dual-camera “stereoscopic” triangulation systems can sense relative position for up to 6 degrees of freedom. However, such known dual-camera systems are generally relatively large systems developed for measuring macroscopic objects and/or their positions, which do not scale well to relatively compact precision position measuring systems usable in close proximity to their target object. Furthermore, the triangulation arrangement of such known systems generally constrains the relationship between the z-axis measurement resolution and the z-axis measurement range in a restrictive and undesirable manner. Systems that can image an object and determine x-y position from a feature in the image and z-axis position and orientation based on varying magnification in the image are also known. However, the magnification arrangement of such known systems generally constrains the relationship between the z-axis measurement resolution and the z-axis measurement range in a restrictive and undesirable manner, and introduces other problems requiring special image processing and/or compensation in order to accurately measure a relative position with up to 6 degrees of freedom. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention is directed to providing a position sensor that overcomes the foregoing and other disadvantages. More specifically, the present invention is directed to an optical position sensor utilizing a scale or target member that emits a structured light pattern (also referred to as a structured light scale, structured light target, or structured light target member), and an imaging array (also referred to as a camera, image detector, optical detector or array detector), to provide high accuracy simultaneous measurements for up to 6 degrees of freedom for an object (multiple-dimension, or “6D”, measurements), including any one of, or combination of, X, Y, Z, yaw, pitch, and roll. Depending on the design parameters chosen for the structured light pattern and the imaging array, the applications of an optical position sensor according to this invention include, but are not limited to, precision position sensors for metrology, motion control systems and the like, as well as relatively lower resolution and/or longer range sensors usable for computer input devices, multi-degree-of-freedom manual machine controllers, macroscopic object ranging and orientation measurement systems, and the like. In accordance with one aspect of the invention, the imaging array is positionable to input a structured light image (also referred to as a target image) arising from the structured light sources (also referred to target sources) on a target member. In various exemplary embodiments, the target sources are arranged in a two-dimensional periodic array on the target member. In accordance with another aspect of the invention, the image on the array detector includes respective image features corresponding to respective target sources on the target member. In accordance with another aspect of the invention, in various exemplary embodiments, the target sources create a diverging structured light pattern. In various other embodiments, the target sources create a converging structured light pattern. In various other embodiments, the target sources create a structured light pattern that converges and then diverges along the central axis of the structured light pattern. In various exemplary embodiments, a target source comprises a refractive axicon point-like lens (an axicon point), a refractive axicon ring, a refractive faceted pyramidal-type point-like lens, a refractive polyhedral-like arrangement of prismatic “lines”, an arrangement of one or more refractive prismatic “lines”, or any combination thereof. In various other exemplary embodiments respective diffractive optical elements, that deflect light rays approximately like the corresponding respective refractive optical elements listed above, may be used instead of refractive optical elements. In accordance with another aspect of the invention, a target source receives collimated light from a light source and outputs the structured light pattern. In accordance with a further aspect of the invention, the target source further comprises a lens or lens portion that causes adjacent rays of the structured light to focus at a plane that is located approximately in the middle of a nominal measuring range along an axis of separation between the imaging array and the target member. In accordance with a further aspect of the invention, in various embodiments where the target source is a point-like lens, the rays of the structured light pattern are arranged at a polar angle relative to an axis that extends from the target source along a direction normal to a face of the target member. The particular polar angle is determined by the characteristics of the point-like lens. The polar angle is furthermore the cone angle of a hypothetical cone with an apex proximate to the target source. Thus, in accordance with a further aspect of the invention, in various exemplary embodiments, the structured light image on the imaging detector (also referred to as an array detector) comprises a continuous, or segmented, circular or elliptical pattern formed where the hypothetical cone intersects with the plane of the optical detector elements of the imaging array. In various embodiments, the segments of the circular or elliptical pattern are essentially spots. In accordance with a further aspect of the invention, the continuous or segmented circular or elliptical (ring-shaped) image corresponding to a target source has a size that varies with the separation along a direction parallel to an axis of separation between the imaging array and the target member. The size of the ring-shaped structured light image corresponding to a target source can thus be used to determine an absolute z-axis coordinate for a corresponding target source or other reference feature relative to the detection plane, or reference plane, of the imaging array. In accordance with a further aspect of the invention, the location of the center of the ring-shaped structured light image corresponding to a target source on the array detector can be used to determine the location of the corresponding target source along a plane parallel to the detection plane, or reference plane, of the imaging array, and can thus be used to determine the displacement of the target source relative to the detection plane, or reference plane, of the imaging array along an x-y plane. Thus, a set of (x,y,z) coordinates can be determined for any such target source, and given the (x,y,z) coordinates of three such target sources, a 6-degree-of-freedom relative position can be determined between a target member and a position measuring device according to this invention. In accordance with another aspect of the invention, the structured light image corresponding to a target source is a slightly blurry image having respective radial intensity profiles comprising the intensity values of respective sets of image pixels of the ring-shaped image feature lying along respective radial directions extending from a nominal center of the ring shaped feature. In various exemplary embodiments according to this invention, a function of a circle or an ellipse is fitted to a set of respective peaks determined for the set of respective radial intensity profiles. In various embodiments, scaling in x and y is performed to correct for magnification or image aberrations before the respective peaks are determined. In either case, the resulting fit function provides a high accuracy estimate of the size (a radial dimension) and center location of the structured light image corresponding to a target source at a sub-pixel interpolation level, and thus can be used to determine the corresponding (x,y,z) coordinates of any corresponding target source, and the resulting relative position determination with a similar high accuracy. In accordance with another aspect of the invention, a position sensing device including various elements outlined above provides images on the array detector that include at least two respective structured light image features corresponding to respective target sources, and when a separation between the position sensing device and the target member is increased, the size of each of the corresponding respective structured light image features increases on the array detector, but a spacing between respective nominal centers of the respective image features does not change on the array detector. In accordance with another aspect of the invention, the target member comprises a plurality of respective unique target source patterns usable to uniquely identify a respective region of the target member. | 20040331 | 20071211 | 20051006 | 76014.0 | 0 | TON, TRI T | SCALE FOR USE WITH A TRANSLATION AND ORIENTATION SENSING SYSTEM | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,815,958 | ACCEPTED | Ball bearing | An outer ring 3a is formed so as to have a large thickness and the pitch circle diameters Dp of balls 6 are shifted to the inside diameter side of the present ball bearing. The radiuses of curvature Ro, Ri of the section shapes of an outer ring raceway 2a and an inner ring raceway 4a are increased with respect to the diameter Db of the balls 6. At the same time, the diameter Db of the balls 6 and the thickness of an inner ring 5a are not set excessively small to thereby be able not only to prevent Brinell impressions from being formed in the outer ring raceway 2a but also to prevent the inner ring 5a from being damaged or cracked. | 1-13. (canceled) 14. A ball bearing comprising: an outer ring including on the inner peripheral surface thereof an outer ring raceway having an arc-shaped section; an inner ring including on the outer peripheral surface thereof an inner ring raceway having an arc-shaped section; and a plurality of balls respectively interposed rollably between said outer and inner ring raceways, wherein, where the outside diameter of said outer ring is expressed as D, the inside diameter of said inner ring is expressed as d, the pitch circle diameter of said respective balls is expressed as Dp, the following equations (1), (2), (3) and (4) can be satisfied: x=Db/{D−d)/2}, (1) y=Dp/{D+d)/2}, (2) x≧0.3, and (3) y<1.0, (4) wherein, where the diameter of said respective balls is expressed as Db, the radius of curvature of the section shape of said outer ring raceway is expressed as Ro, and the radius of curvature of the section shape of said inner ring raceway is expressed as Ri, the following equations (5) and (6) can be satisfied: 0.53<Ro/Db≦0.65, and (5) 0.52<Ri/Db≦0.65. (6) 15. The ball bearing according to claim 14, wherein the diameter of an inner ring raceway whose maximum circumferential stress provides 294 MPa (30 kgf/mm2) under the condition that, in case where d is in the range 6-10 mm, the interference of said inner ring is 11 μm and in case where d is in the range of more than 10 mm up to 18 mm, the interference of said inner ring is 12 μm, is expressed as Di, the following equation (7) can be satisfied: y≧{(D−d)/(D+d)}x+2Di/(D+d). (7) 16. The ball bearing according to claim 14, wherein, in case where the inside diameter d of said inner ring is less than 6 mm, under the condition that the interference of said inner ring is expressed by a curved line allowing the following three points, which are plotted in perpendicular coordinates in which the inner ring inside diameter d is shown in one of the vertical and horizontal axes thereof and the inner ring interference is shown in the other, to be smoothly continuous with one another, a first point where said inner ring interference is 6 μm for said inner ring inside diameter of 5 mm, a second point where said inner ring interference is 2 μm for said inner ring inside diameter of 4 mm, and a third point where said inner ring interference is 1 μm for said inner ring inside diameter of 3 mm, when the diameter of an inner ring raceway providing the maximum circumferential stress of 294 MPa (30 kgf/mm2) is expressed as Di, the following equation (8) can be satisfied: y≧{(D−d)/(D+d)}x+2Di/(D+d). (8) 17. The ball bearing according to claim 14, wherein said outer ring, said inner ring and said balls are made of bearing steel. 18. The ball bearing according to claim 14, wherein the value of y is set equal to or less than 0.95. 19. The ball bearing according to claim 14, wherein the value of y is set equal to or less than 0.9. | BACKGROUND OF THE INVENTION The present invention relates to a ball bearing, and particularly a ball bearing used to support a rotary shaft, which is disposed in a fan motor of an electric cleaner for domestic use or in a blower of an air conditioner for domestic use and is to be rotated at a high speed with a low load, in such a manner that the rotary shaft can be rotated freely with respect to a housing. Conventionally, such a ball bearing 1 as shown in FIG. 11 is widely used to support a rotary shaft, which is disposed in various apparatus, in such a manner that it can be freely rotated with respect to a housing. The ball bearing 1 comprises an outer ring 3 including on the inner peripheral surface thereof a deep-groove type of outer ring raceway 2 having an arc-shaped section, an inner ring 5 including on the outer peripheral surface thereof an inner ring raceway 4 having an arc-shaped section, and a plurality of balls 6 respectively interposed between the outer and inner ring raceways 2 and 4 so as to be free to roll; and, the outer ring 3, inner ring 5 and balls 6 are all made of bearing steel such as SUJ2 or M50, ceramic, or the like. The balls 6 are respectively held by a retainer 7 in such a manner that they are able to roll while they are spaced from one another. Also, to the inner peripheral surfaces of the two end portions of the outer ring 3, there are secured the outer peripheral edge portions of sealed rings 8 and 8, whereas the inner peripheral edge portions of the sealed rings 8 and 8 are respectively disposed so as to be close and opposed to the outer peripheral surfaces of the two end portions of the inner ring 5. By the way, in the case of the conventional ball bearing 1, generally, where the diameter of the respective balls 6 is expressed as Db, the radius of curvature of the section shape of the outer ring raceway 2 is expressed as Ro′, and the radius of curvature of the section shape of the inner ring raceway 4 is expressed as Ri′, the following equations are established; that is, 0.50<Ro′Db<0.53, and 0.50<Ri′/Db≦0.52. Also, where the outside diameter of the outer ring 3 is expressed as D, the inside diameter of the inner ring 5 is expressed as d, and the pitch circle diameter (P.C.D.) of the respective balls 6 is expressed as Dp′, the following equation is established; that is, Dp′≈(D+d)/2. In other words, there is employed the equation, that is, Dp′/(D+d)/2≈1, and the respective balls 6 are positioned substantially in the middle of the outer peripheral surface of the outer ring 3 and the inner peripheral surface of the inner ring 5 with respect to the diameter direction of the ball bearing 1. In case where the above-structured ball bearing 1 is used to support, for example, the rotary shaft of a fan motor disposed in a suction device employed in an electric cleaner, the outer ring 3 is inserted and fixed to a fixed housing, while the inner ring 5 is outserted and fixed to the rotary shaft. The above-mentioned conventional ball bearing 1 has a general-purpose structure which aims for assembly into one of various rotation support portions, but does not prefer to apply under the low-load and high-speed rotation condition, and, therefore, the rotation torque (rotation resistance) thereof is not always low. On the other hand, there has been increasing a demand for reducing the rotary torque of the rotation support portion in order to be able to cope with a rising energy saving tendency in recent years. In view of such circumstances, it is an urgent need to realize a ball bearing which not only provides a small rotation torque but also can be incorporated into the rotation support portion which rotates at a high speed with a low load. As the simplest means for reducing the rotation torque, it can be expected that, as grease to be applied to the portion where the balls 6 are disposed, grease having low viscosity is used. However, there is a limit to the torque reduction that can be realized by reducing the viscosity of the grease and, therefore, in order to be able to realize large torque reduction, it is necessary to change the structure of the ball bearing itself. In case where the rotation torque of the rotation support portion rotating at a high speed with a low load is reduced by changing the specifications of the ball bearing, use of a ball bearing whose diameter and diameter-associated elements are reduced in size (that is, a small-sized ball bearing) can realize rather large torque reduction. However, in this case, it is necessary to reduce the inside diameter of a housing into which the outer ring is inserted and fixed, which unfavorably requires the design change of the remaining component members of the rotation support portion. Also, even in case where the diameter and its associated elements of the ball bearing are simply reduced in size, there still remains a possibility that sufficient torque reduction cannot be realized. SUMMARY OF THE INVENTION The present invention aims at eliminating the above-mentioned drawbacks found in the conventional ball bearing. Accordingly, it is an object of the invention to provide a ball bearing which not only can realize a low torque structure but also can be assembled to a housing similar to the conventional ball bearing. In attaining the above object, according to a first aspect of the invention, there is provided a ball bearing which, similarly to the above-mentioned conventional ball bearing, comprises an outer ring including on the inner peripheral surface thereof an outer ring raceway having an arc-shaped section; an inner ring including on the outer peripheral surface thereof an inner ring raceway having an arc-shaped section; and, a plurality of balls respectively and interposed rollably between the outer and inner ring raceways. Especially, in the ball bearing according to the invention, where the outside diameter of the outer ring is expressed as D, the inside diameter of the inner ring is expressed as d, the pitch circle diameter of the respective balls is expressed as Dp, the diameter of the groove bottom of an inner ring raceway whose maximum circumferential stress provides (294 MPa) 30 kgf/mm2 under the condition that, in case where d is in the range 6 -10 mm, the interference of the inner ring is 11 μm and in case where d in the range of more than 10 mm up to 18 mm, the interference of the inner ring is 12 μm, is expressed as Di, x=Db/{(D−d)/2), and y=Dp/{(D+d)/2}, the following equations (1) to (2) can be satisfied, and also the following equation (3) can be preferably satisfied: that is, x≧0.3 (1) y<1.0 (2) y≧{(D−d)/(D+d)}x+2Di/(D+d) (3). Also, preferably, where the diameter of the respective balls is expressed as Db, the radius of curvature of the section shape of the outer ring raceway is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway is expressed as Ri, the following equations (4) and (5) can be satisfied: that is, 0.53<Ro/Db≦0.65 (4) 0.52<Ri/Db≦0.65 (5). In the case of the above-structured ball bearing according to the first aspect of the invention, not only sufficient durability can be secured but also sufficient rotation torque reduction can be realized without changing the outside diameter of the outer ring specially. That is, in order to satisfy the equation (2), the plurality of balls are positioned on the inside diameter side of the ball bearing. This can reduce the moment necessary to roll these balls, thereby being able to reduce the rotation torque of the ball bearing. In this manner, even when reducing the rotation torque of the ball bearing, in order to satisfy the equation (1), by securing the diameter Db of the balls, the contact ellipses in the contact portions between the balls and outer ring raceway can be prevented from decreasing in size excessively, which can prevent Brinell impressions from occurring in the outer ring raceway. Further, in order to satisfy the equation (3), by securing the pitch circle diameter Dp of the balls, even when the inner ring is outserted onto the rotary shaft, circumstantial stress occurring in the inner ring can be prevented from increasing excessively, which can prevent the inner ring against damage such as occurrence of a crack. By the way, in the equation (3), the inner ring raceway (groove bottom) surface Di depends on the fit standard js5 specified in JIS and on the strength that is required of the inner ring. That is, according to the js5, the upper limit value of the interference of an inner ring is 11 μm in the case of an inner ring having an inside diameter of 6 -10 mm and, in the case of an inner ring having an inside diameter of 10 -18 mm, it is 12 μm. Further, the outer ring, the inner ring and the plurality of balls are preferably made of bearing steel. Generally, the inner ring raceway surface Di having an influence on the thickness of the groove bottom of the inner ring is specified in such a manner that the maximum stress of bearing steel can be of 137.2 MPa (14 kgf/mm2) or less. However, actually, depending on the selection of the material of the inner ring and on the change of the thermal treatment thereof, up to the stress of 294 Mpa (30 kgf/mm2), the thickness of the groove bottom can be reduced. For this reason, the inner ring raceway surface Di is set at the value where the maximum circumstantial stress provides 294 MPa (30 kgf/mm2) By the way, referring to the ratio R1/Db between the diameter Db of each ball and the radius of curvature R1 of the section shape of the inner ring raceway, as in a fan motor used in a blower of an air conditioning apparatus, when the fan motor is used at a speed of 10,000 min−1 (r.p.m.) or less, the ratio is set such that 0.52<R1/Db<0.65; but, as in a fan motor used in a suction device of an electric cleaner, when the fan motor is used at a speed of 20,000 min−1 (r.p.m.) or more, preferably, the ratio may be set such that 0.53<R1/Db≦0.65. Moreover, by satisfying the above equations (4) and (5), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls and the outer ring and inner ring raceways can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing. By the way, in case where the values of Ro/Db and Ri/Db exceed 0.65 and increase excessively, the area of each of the contact ellipses is reduced excessively, which makes it difficult to secure the rolling fatigue lives of the outer and inner ring raceways; and, especially, in the case of the outer ring raceway, Brinell impressions are easy to occur. For these reasons, the upper limit values of Ro/Db and Ri/Db are set at 0.65. In attaining the above object, according to a second aspect of the invention, there is provided a ball bearing for use in an electric cleaner which comprises an outer ring made of bearing steel and including on the inner peripheral surface thereof an outer ring raceway having an arc-shaped section; an inner ring made of bearing steel and including on the outer peripheral surface thereof an inner ring raceway having an arc-shaped section; and, a plurality of balls respectively made of bearing steel and interposed rollably between the outer and inner ring raceways. And, the present electric cleaner ball bearing is incorporated into the rotation support portion of the electric cleaner and is used in such a manner that the outer ring is fixed and the inner ring is rotated at the speed of 40,000-60,000 min−1 (r.p.m). Especially, in the ball bearing according to the second aspect of the invention, where the diameter of the respective balls is expressed as Db, the radius of curvature of the section shape of the outer ring raceway is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway is expressed as Ri, the following equations (1) and (2) can be satisfied: that is, 0.58≦Ro/Db≦0.61 (1) 0.52≦Ri/Db≦0.61 (2) In the case of the above-structured ball bearing for an electric cleaner according to the second aspect of the invention, not only sufficient durability can be secured but also sufficient rotation torque reduction can be realized without reducing the outside diameter of the outer ring specially. That is, by satisfying the above equations (1) and (2), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls and the outer ring and inner ring raceways, can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing. By the way, the reason why, as described above, the ratios of the radius of curvature of the section shape of the outer ring raceway Ro and the radius of curvature of the section shape of the inner ring raceway Ri to the diameter of the respective balls Db are respectively set in the range of 58-61% is as follows. That is, as these ratios increase, the contact ellipses formed in the respective contact portions decrease in size, thereby being able to reduce the rotation torque of the ball bearing. Therefore, in order to reduce the rotation torque of the ball bearing, it is preferred to increase these ratios (that is, Ro/Db and Ri/Db). On the other hand, in case where these ratios are increased, the surface pressures of the respective contact portions increase, which lowers the exfoliation lives of the outer ring raceway and inner ring raceways. Here, FIG. 10 shows the relation between the above ratios and the exfoliation lives of the outer and inner raceways under the operation conditions (rotation speed=60,000 min−1 (r.p.m.), and preload of 49 N (5 kgf)} of a ordinary electric cleaner ball bearing (the outside diameter D of an outer ring=22 mm, the inside diameter d of an inner ring=8 mm, and the width B of the ball bearing=7 mm). As can be seen clearly from FIG. 10, Generally, when the durability of the rotation support portion is taken into account, it is not expedient to form outer and inner ring raceways having such large radiuses of curvature that provide the ratios (that is, Ro/Db and Ri/Db) of more than 56%. On the other hand, as in an electric cleaner ball bearing to which the present invention relates, when a ball bearing is used under the conditions that the rotation portion is rotated at a high speed with a low load and dust such as brush friction powder can invade into the interior portion of the ball bearing, the life of the ball bearing depends, in many cases, on the occurrence of seizure rather than on the coming of the exfoliation life. And, due to the enhanced speed of the rotation of the rotation support portion, in many cases, such seizure occur in the range of 2,000-3,000 hours. Therefore, it is no expedient that, in order to obtain an exfoliation life which exceeds greatly 2,000-3,000 hours, the above ratios are reduced (that is, the ratios are approximated to 50%), because this increases the rotation torque of the ball bearing. When such circumstances are taken into consideration, in case where the above ratios are respectively set in the range of 58-61%, not only a practically sufficient exfoliation life can be secured but also the rotation torque of the ball bearing can be reduced to a sufficient degree. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial section view of a first example of a mode for carrying out the invention; FIG. 2 is a graphical representation of the technical scope of the invention; FIG. 3 is a partial section view of a second example of a mode for carrying out the invention; FIGS. 4(A) and 4(B) shows a test apparatus used to confirm the effects of the invention; in particular, FIG. 4(A) is an end view thereof and FIG. 4(B) is a section view thereof; FIGS. 5(A), 5(B) and 5(C) are graphical representations of the results of a test conducted to confirm the influence of a pitch circle diameter on the rotation torque of a ball bearing; FIGS. 6(A) and 6(B) are bar graphs of the results of a test conducted to confirm the influences of the ratios of the radiuses of curvature of outer and inner ring raceways to the ball diameter on the rotation torque of a ball bearing; FIG. 7 is bar graphs of the results of a test conducted to confirm the influences of the difference in the pitch circle diameter with respect to a relationship between ANDELON value and Motor Noise; FIG. 8 is a partial section view of a third example of a mode for carrying out the invention; FIG. 9 is a graphical representation of the results of a test conducted to confirm the effects of the invention; FIG. 10 is a graphical representation of the influences of the ratios of the radiuses of curvature of outer and inner ring raceways to the ball diameter on the exfoliation lives of the outer and inner ring raceways; and FIG. 11 is a partial section view of a conventional ball bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, FIG. 1 shows a first example of a mode for carrying out the invention. According to the present mode, a ball bearing la, similarly to the conventionally known ball bearing 1 that is shown in the above-mentioned FIG. 11, comprises an outer ring 3a including on the inner peripheral surface thereof a deep-groove type of outer ring raceway 2a having an arc-shaped section, an inner ring 5a including on the outer peripheral surface thereof an inner ring raceway 4a having an arc-shaped section, and a plurality of balls 6 respectively interposed between the outer and inner ring raceways 2a and 4a so as to be free to roll. The balls 6 are respectively held by a retainer 7 in such a manner that they are able to roll while they are spaced from one another. Also, to the inner peripheral surfaces of the two end portions of the outer ring 3a, there are secured the outer peripheral edge portions of sealed rings 8 and 8, while the inner peripheral edge portions of the sealed rings 8 and 6 are respectively disposed so as to be close to but opposed to the outer peripheral surfaces of the two end portions of the inner ring 5a. The outer ring 3a, the inner ring 5a and the plurality of balls 6 are preferably made of bearing steel, such as SUJ2, M50 or the like in this embodiment. It is, however, possible to make them with a steel, a ceramic or the like instead of the bearing steel, if required. Especially, in the case of the ball bearing 1a according to the invention, where the outside diameter of the outer ring 3ais expressed as D, the inside diameter of the inner ring is expressed as d, the pitch circle diameter of the respective balls 6 is expressed as Dp, the diameter of an inner ring raceway whose maximum circumferential stress provides 294 MPa (30 kgf/mm2) under the condition that, in case where d is in the range 6-10 mm, the interference of the inner ring is 11 μm, and in case where d in the range of more than 10 mm up to 18 mm, the interference of the inner ring is 12 μm, is expressed as Di, x=Db/{(D−d)/2}, and y=Dp/{(D+d)/2), the following equations (1) to (2) can be satisfied, and also the following equation (3) can be preferably satisfied: that is, x≧0.3 (1) y<1.0 (2) y≧{(D−d)/(D+d)}x+2Di/(D+d) 3) Also, where the diameter of the respective balls 6 is expressed as Db, the radius of curvature of the section shape of the outer ring raceway 2a is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway 4a is expressed as Ri, the following equations (4) and (5) can be satisfied: that is, 0.53<Ro/Db≦0.65 (4) 0.52<Ri/Db≦0.65 (5). In case where the above-structured ball bearing 1a is used to support, for example, the rotary shaft of a fan motor for a suction device employed in an electric cleaner, the outer ring 3a is inserted into and fixed to a fixed housing, while the inner ring 5a is outserted and fixed to the rotary shaft. By the way, the ball bearing 1a according to the invention is a ball bearing which not only is used to support the rotary shaft of a domestic-use electric cleaner or the rotary shaft of a blower of a domestic-use air conditioner on a housing but also is used under a low-load and high-speed rotation condition. Referring more specifically to the size of the ball bearing 1a, the outside diameter D of the outer ring 3a is of the order of 15-40 mm, the inside diameter d of the inner ring 5a is of the order of 6-18 mm, and the width B of the ball bearing 1a is of the order of 5-12 mm. By the way, a case, in which the inside diameter d of the inner ring 5a is less than 6 mm, can also fall under the scope of the invention. In this case, D1 in the equation (3) expresses the diameter of an inner ring raceway which provides the maximum circumferential stress of 294 MPa (30 kgf/mm2), under the condition that the interference of the inner ring is expressed by a curved line allowing the following three points to be smoothly continuous with one another, that is, a first point where the inner ring interference is 6 μm for the inner ring inside diameter of 5 mm, a second point where the inner ring interference is 2 μm for the inner ring inside diameter of 4 mm, and a third point where the inner ring interference is 1 μm for the inner ring inside diameter 3 mm. That is, based on a curved line which allows the above three points, which are plotted in perpendicular coordinates in which the inner ring inside diameter d is shown in one of the vertical and horizontal axes thereof and the inner ring interference is shown in the other, to be smoothly continuous with one another, there is obtained an inner ring raceway whose maximum circumferential stress provides 294 MPa and the diameter of the present inner ring raceway is expressed as D1. In case where the inside diameter d is less than 6 mm, there is a possibility that not only the outer ring outside diameter D can be less than 15 mm but also the width B can be less than 5 mm. In the case of the above-structured ball bearing 1a according to the invention, not only sufficient durability can be secured but also, without reducing the outside diameter of the outer ring specially, sufficient rotation torque reduction can be realized. Now, description will be given below of such characteristics of the present ball bearing 1a with reference to FIG. 2. Here, in FIG. 2, the above-mentioned x=Db/{(D−d)/2) is shown by the horizontal axis, and y=Dp/{(D+d)/2) is shown by the vertical axis, respectively; and, a triangular portion, the three sides of which are surrounded by three straight lines A, B and C and also which is shown by oblique checks, shows the technical scope of the invention. By the way, a straight line D, which is situated downwardly of the triangular portion, shows a portion in which the thickness of the inner ring 5a provides 0 in the above-mentioned inner ring raceway 4a portion. Therefore, downwardly of the straight line D, the present ball bearing cannot be established. At first, in the case of the ball bearing la according to the invention, in order to satisfy the equation (2), the thickness of the outer ring 3a with respect to the diameter direction of the ball bearing 1a is set larger than the thickness of the inner ring 5a, and the positions of the balls 6 (that is, pitch circle diameters thereof) are arranged on the inside diameter side of the ball bearing 1a. That is, by manufacturing the ball bearing 1a downwardly of the straight line A in FIG. 2, the moment that is necessary to roll the balls 6 can be reduced to thereby be able to reduce the rotation torque of the ball bearing 1a. In this manner, even in case where the rotation torque of the ball bearing 1a is reduced, it is not necessary to reduce the outside diameter D of the outer ring 3a over the conventional structure and thus it is not necessary to change the inside diameter of the housing to which the outer ring 3a is to be inserted and fixed. Therefore, the housing, which has been conventionally used, can be used as it is. By the way, in order that, without reducing the outside diameter D of the outer ring 3a, the pitch circle diameter Dp is reduced to thereby be able to reduce the torque, there is set such that y<1 as in the equation (2). However, in order to be able to reduce the torque sufficiently, preferably, the value of y may be set equal to or less than 0.95 and, more preferably, the value of y may be set equal to or less than 0.9. The lower limit value of y is restricted by a straight line C shown in FIG. 2. Also, in order to satisfy the equation (5), by securing the diameter Db of the balls 6, the contact ellipses in the contact portions between the rolling surfaces of the balls 6 and the outer ring raceway 2a can be prevented from being excessively reduced in size, which in turn can prevent Brinell impressions from being caused in the outer ring raceway 2a. That is, the diameter Db of the balls 6 is secured in such a manner that the ball bearing 1a can be manufactured on the right side of the straight line B in FIG. 2. By the way, the outer ring raceway 2a is structured in such a manner that not only its cross section extending in the axial direction of the ball bearing 1a is a concave surface but also its cross section extending in the circumferential direction of the ball bearing 1a is also a concave surface. The thus structured outer ring raceway 2a is smaller in yield strength with respect to a pressing force applied thereto than the inner ring raceway 4a whose cross section extending in the circumferential direction of the ball bearing 1a is a convex surface. Thus, even when the radius of curvature Ro of the cross section of the outer ring raceway 2a is increased in order to reduce the contact ellipses in size, in case where the diameter Db of the balls 6 is secured to a certain degree, it is possible to prevent the contact ellipses from being reduced in size excessively. More specifically, by satisfying the equation (1), the maximum surface pressure to be applied onto the outer ring raceway 2a is controlled down to 1960 MPa (200 kgf/mm2) or less, which makes it possible to prevent the Brinell impressions from being caused in the outer ring raceway 2a. Further, in order to satisfy the equation (3), in case where the pitch circle diameter Dp of the balls 6 is secured to thereby outsert the inner ring 5a to the rotary shaft, it is possible to prevent circumferential stresses caused in the inner race 5a from increasing excessively. That is, the pitch circle diameter Dp and diameter Db of the balls 6 are restricted so as to exist upwardly of the straight line C in FIG. 2. By the way, when the ball bearing 1a is in use, the inner ring 5a is outserted and fixed to the rotary shaft by close fit. Therefore, to the inner ring 5a, when it is in use, there is applied a tensile stress which acts in the circumferential direction thereof. In case where the tensile stress becomes excessively large, there is a possibility that there can be caused damage such as a crack in the inner ring 5a. However, in case where the equation (3) is satisfied, the maximum tensile stress can be controlled down to 294 Mpa (30 kgf/mm2) or less, which makes it possible to prevent the inner ring 5a against such damage. In addition, by satisfying the above equations (4) and (5), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls 6 and the outer ring and inner ring raceways 2a, 4a, can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing 1a. Next, FIG. 3 shows a second example according to a mode for carrying out the invention. In the present example, in the central portion of the inner peripheral surface of the outer ring 3b where there is formed an outer ring raceway 2a, there is formed a center projecting portion 15 having a diameter which is sufficiently smaller than the diameters of the two end portions of the inner peripheral surface in the axial direction thereof. And, between the two side surfaces of the center projecting portion 15 and the inner surfaces of sealed rings 8, 8 whose outer peripheral edges are respectively secured to the two end portions of the inner peripheral surface of the outer ring 3b, there are formed hold recessed portions 16, 16 which respectively extend over the whole periphery of the associated surfaces. These hold recessed portions 16, 16 respectively function as grease storage portions and can continue to supply lubricating oil to the contact portions between the rolling surfaces of the balls 6 and the outer ring raceway 2a, inner ring raceway 4a for a long period of time. In the case of the invention, since the thickness of the outer ring 3b in the diameter direction thereof is set large, the capacities of the hold recessed portions 16, 16 can be increased and thus the grease hold quantities thereof can be increased, thereby being able to enhance the durability of the ball bearing 1b. The remaining portions of the structure and operation of the present example are similar to those of the previously described first example. Now, description will be given below of the results of the tests that were conducted for confirmation of the effects of the first aspect of the invention. Specifically, there were conducted the following three kinds of tests: that is, a test (a first test) which was conducted in order to know the influence of the pitch circle diameter Dp of the ball 6 on the rotation torque of the ball bearing; a test (a second test) conducted in order to know the influence of the radiuses of curvature of the section shapes of the respective raceways on the rotation torque of the ball bearing; and, a test (a third test) conducted in order to know the influences of the pitch circle diameter Dp of the ball 6 and the diameter Db of the ball 6 on the noise that is produced by the motor. In these tests, except for part of them, there was used a ball bearing of a deep groove type in which the outside diameter D of the outer ring 3a is 22 mm, the inside diameter d of the inner ring 5a is 8 mm, and the width B of the bearing is 7 mm. As will be discussed later, in these tests, there were prepared eleven kinds of embodiments which fall under the technical scope of the invention, and seven kinds of comparison examples which do not fall under the technical scope of the invention, that is, a total of eighteen kinds of test samples. The outer ring 3a, inner ring 5a and balls 5 were all made of SUJ2. Embodiment 1 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.45 Number of balls=8 Embodiment 2 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.89 Number of balls=10 Embodiment 3 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.57 y=Dp/{(D+d)/2}=0.90 Number of balls=6 Embodiment 4 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.85 Number of balls=7 Embodiment 5 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls =9 Embodiment 6 Ro/Db=0.56 Ri/Db=0.56 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.92 Number of balls=8 Embodiment 7 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.92 Number of balls=8 Embodiment 8 Ro/Db=0.65 Ri/Db=0.65 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.92 Number of balls=8 Embodiment 9 Ro/Db=0.56 Ri/Db=0.56 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls=10 Embodiment 10 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls=10 Embodiment 11 Ro/Db=0.65 Ri/Db=0.65 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls=10 COMPARISON EXAMPLE 1 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.57 y=Dp/{(D+d)/2}=1.00 Number of balls=7 COMPARISON EXAMPLE 2 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=1.00 Number of balls=9 COMPARISON EXAMPLE 3 Ro/Db=0.60 Ri/Db=0.60 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=1.00 Number of balls=11 COMPARISON EXAMPLE 41 Ro/Db=0.51 Ri/Db=0.51 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.92 Number of balls=8 COMPARISON EXAMPLE 5 Ro/Db=0.53 Ri/Db=0.52 x=Db/{(D−d)/2}=0.45 y=Dp/{(D+d)/2}=0.92 Number of balls=8 COMPARISON EXAMPLE 6 Ro/Db=0.51 Ri/Db=0.51 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls=10 COMPARISON EXAMPLE 7 Ro/Db=0.53 Ri/Db=0.52 x=Db/{(D−d)/2}=0.34 y=Dp/{(D+d)/2}=0.79 Number of balls=10 Now, at first, of the above-mentioned eighteen kinds of samples, using the five embodiments 1-5 and three comparison examples 1-3, that is, a total of eight kinds of samples, the influence of the pitch circle diameter Dp of the balls 6 on the rotation torque of the ball bearing was confirmed by using such a test apparatus 9 as shown in FIG. 3. The test apparatus 9 comprises a rotary shaft 10 and a housing 11 which are disposed concentric with each other. In measuring the above rotation torque, ball bearings 1a, 1a having the same structure were assembled between the outer peripheral surface of the rotary shaft 10 and the inner peripheral surface of the housing 11 and, after then, the rotary shaft 10 was rotated, whereby rotation torque applied to the leading end portion of an arm 12 fixed to the outer peripheral surface of the housing was measured by a load sensor 13. By the way, in every sample, grease for lubrication was applied into the ball bearings 1a, 1a and two end portions of the ball bearings 1a, 1a were sealed by sealed rings 8, 8 each of a non-contact type (see FIG. 1). Also, the test apparatus was operated at room temperature in the air. Further, a preload of 49N (5 kgf) was applied to the respective ball bearings 1a, 1a using a spring 14. The rotation speed (dmn=the product of the pitch circle diameter and the number of rotations per minute) of the rotary shaft 10 was varied in the range of four hundred thousand to nine hundred thousand (400000-900000) dmn, and the rotation torque after the passage of ten minutes from the start of the operation of the test apparatus was measured. The results of the test conducted in this manner are shown in FIG. 4. In FIG. 4 (A) shows the relation between the rotation speed and rotation torque in the embodiment 3 and comparison example 1 in which only the value of y=Dp/}(D+d)/2} and the number of balls were varied. Also, (B) shows the relation between the rotation speed and rotation torque in the embodiments 1, 4 and comparison example 2 in which only the value of y=Dp/{(D+d)/2} and the number of balls were varied. Further, (C) shows the relation between the rotation speed and rotation torque in the embodiments 2, 5 and comparison example 3 in which only the value of y=Dp/{(D+d)/2} and the number of balls were varied. And, in FIGS. 4 (A)-(C), the value of the rotation torque in 900000 d mn in the respective comparison examples is assumed to be 1, and the values of the rotation torque occurring in the remaining rotation speeds (dmn) are expressed as the ratios with respect to the reference value, that is, 1. Similar tests, as shown in Tables 1 and 2, were made while changing the sizes of the ball bearings and, according to the results of these tests, it has been confirmed that to reduce the size of the pitch circle is effective in reducing the rotation torque of the bearing. TABLE 1 Dp = 15 (mm) Dp = 13 (mm) Maximum Value 196 107.8 Averaged Value 176.4 88.2 Minimum Value 156.8 58.8 TABLE 2 Dp = 23 (mm) Dp = 21.5 (mm) Maximum Value 1332.8 735 Averaged Value 1225 705.6 Minimum Value 1078 686 By the way, of the tests the results of which are shown in these tables 1 and 2, the test the results of which are shown in the table 1, as described above, was conducted using a ball bearing of a deep groove type in which the outside diameter D of an outer ring 3a is 22 mm, the inside diameter d of an inner ring 4a is 8 mm, and the width B of the bearing is 7 mm. Also, the ratio of the grease quantity with respect to the capacity of a gap existing between the outer ring 3a and inner ring 4a (that is, the grease filling ratio) was set at 35%, and the rotation speed of the motor was set at 1800 min−1. On the other hand, the test the results of which are shown in the table 2 was conducted using a ball bearing of a deep groove type in which the outside diameter D of an outer ring 3a is 32 mm, the inside diameter d of an inner ring 4a is 15 mm, and the width B of the bearing is 9 mm. Also, the ratio of the grease quantity with respect to the capacity of a gap existing between the outer ring 3a and inner ring 4a was set at 30%, and the rotation speed of the motor was set at 1800 min−1. Here, the unit that is used to express the value of the rotation torque shown in Tables 1 and 2 is mN·cm. As can be seen clearly from FIGS. 5(A) to (C) and from Tables 1, 2, by reducing the value of the pitch circle diameter Dp, the rotation torque of the ball bearing can be reduced regardless of the size of the ball bearing. Next, of the above-mentioned eighteen kinds of samples, using the five embodiments 6-11 and three comparison examples 4-7, that is, a total of ten kinds of samples, the influences of the radius of curvature Ro of the section shape of the outer ring raceway 2a and the radius of curvature Ri of the section shape of the inner ring raceway 4a on the rotation torque of the ball bearing were confirmed also by the test apparatus 9 as shown in FIG. 3. The test conditions of this test were the same as in the above-mentioned test conducted on the pitch circle diameter Dp. The results of the test conducted in this manner are shown in FIGS. 6(A) and 6(B). FIG. 6(A) shows the values of the rotation torque at the rotation speed of 900000 dmn respectively in the embodiments 6-8 and comparison examples 4, 5 in which only the ratios of the radiuses of curvature Ro, Ri of the outer and inner ring raceways to the ball diameter Db were varied. Also, FIG. 6(B) shows the values of the rotation torque at the rotation speed of 900000 dmn respectively in the embodiments 9-11 and comparison examples 6, 7 in which only the ratios of the radiuses of curvature Ro, Ri to the ball diameter Db were varied. In both of FIGS. 6(A) and 6(B), the value of the rotation torque at the rotation speed of 900000 dmn in the comparison example that is largest in the rotation torque is assumed to be 1, and the values of the rotation torque respectively in the remaining rotation speeds (dmn) are expressed as the ratios with respect to the reference value, that is, 1. As can be seen clearly from FIGS. 5(A)-(C), by reducing the values of the ratios of the radiuses of curvature Ro, Ri to the ball diameter Db, the rotation torque can be reduced. In the next table 3, the influences of the radiuses of curvature of the section shapes of the raceways on the values of the rotation torque are shown more specifically using numerical values. The test the results of which are shown in the table 3 was conducted using a ball bearing of a deep groove type in which the outside diameter D of an outer ring 3a is 22 mm, the inside diameter d of an inner ring 4a is 8 mm, and the width B of the bearing is 7 mm. And, the ratio of the grease quantity with respect to the capacity of a gap existing between the outer ring 3a and inner ring 4a was set at 30%, and the rotation speed of the motor was set at 1800 min−1. Also, the radius of curvature of the outer ring raceway 2a was left unchanged at R/Db=0.53, whereas only the radius of curvature of the inner ring raceway 4a was changed in two ways, that is, R1Db was changed to 0.51 and 0.52. By the way, as a unit of the value of the torque shown in Table 3, there is also used mN cm. Table 3 also shows that, by increasing the value of the ratios of the radiuses of curvature R, R1 of the respective raceways to the diameter Db of the rolling bodies, the rotation torque of the ball bearing can be reduced. TABLE 3 R1/Db = 0.51 R1/Db = 0.52 Maximum Value 196 176.4 Averaged Value 176.4 147 Minimum Value 156.8 127.4 Next, description will be given below of the third test which was conducted in order to know the influences of the pitch circle diameter Dp of the ball 6 and the diameter Db of the ball 6 on ANDELON value and the motor noise. At first, the test aiming at confirming the influences of the pitch circle diameter Dp of the ball 6 and the diameter Db of the ball 6 on the ANDELON value was conducted using a ball bearing of a deep groove type in which the outside diameter D of an outer ring 3a is 22 mm, the inside diameter d of an inner ring 4a is 8 mm, the width B of the bearing is 7 mm, and the grease filling ratio is set at 35%. Under this condition, there were prepared two-kinds of samples, two or more samples for each kinds: in one of the two kinds, the pitch circle diameter Dp of the ball 6 is set at 15 mm, and the diameter Db of the ball 6 is set at 3.97 mm ({fraction (5/32)} inches); and, in the other, the pitch circle diameter Dp of the ball 6 is set at 13 mm, and the diameter Db of the ball 6 is at 3.18 mm (⅛ inches). And, the ANDELON values (High-Band) were measured. The results of the measurement are shown in the next table 4. TABLE 4 Dp = 15 (mm) Dp = 13 (mm) Db = {fraction (5/32)} (inch) Db = ⅛ (inch) Maximum Value 1.2 1.1 Averaged Value 1.1 0.9 Minimum Value 0.9 0.7 As can be seen clearly from Table 4 which shows the results of the above-mentioned test, as in the invention, in case where the pitch circle diameter Dp of the ball 6 is reduced to thereby reduce the diameter Db of the ball 6, the ANDELON values can be enhanced. The reason for this is believed that the reduction in the diameter of the balls 6 reduces the kinetic energy of the balls 6 to thereby reduce the vibratory forces that are produced by the balls 5. Also, there was conducted a test in order to know the values of the motor noises that are produced when ball bearings having different pitch circle diameters Dp but having the same ANDELON values are actually incorporated into a motor. In this test, there was used a ball bearing of a deep groove type in which the outside diameter D of an outer ring 3a is 32 mm, the inside diameter d of an inner ring 5a is 15 mm, and the width B is 9 mm. Under this condition, there were prepared two kinds of samples, two or more samples for each kind: that is, in one of the two kinds, the pitch circle diameter Dp of the ball is set at 21.5 mm; and, in the other, the pitch circle diameter Dp of the ball is set at 23 mm. Specifically, in this test, after the respective ANDELON values (High-Band) of the samples of the two kinds were measured, there were measured the motor noises that were produced in a state that the respective bearings were incorporated into the motor. The measured results of this test are shown in FIG. 7. In FIG. 7, there are shown six marks for each of the two kinds of samples respectively having different pitch circle diameters Dp, that is, a total of twelve marks. Of these twelve marks, a white round mark expresses the average value of the motor noises that were produced when using the ball bearing whose pitch circle diameter DP is 21.5 mm, a white triangular mark expresses the maximum value thereof, and a while square mark expresses the minimum value thereof, respectively; and, a black round mark expresses the average value of the motor noises that were produced when using the ball bearing whose pitch circle diameter Dp is 23 mm, a black triangular mark expresses the maximum value thereof, and a black square mark expresses the minimum value thereof, respectively. As can be seen clearly from FIG. 7 which shows the results of the above test, in case where the pitch circle diameter Dp is reduced, even when the ANDELON value is worsened, there can be prevented an increase in the value of the motor noise that is produced when the ball bearing is actually incorporated into the motor. The reason for this is believed that, in case where the pitch circle diameter Dp is reduced, instead of reducing the diameter Db of the balls to thereby increase the number of the balls, the diameter Db of the balls can be reduced and, therefore, of the vibration components of the balls, the number of resonance peaks included in the resonance frequency range with respect to the motor is reduced, which operates to advantage in sound. This means that, for the purpose of reducing the motor noise, it is not necessary to reduce the ANDELON value so much. In other words, without carrying out a severe quality control for the purpose of reducing the ANDELON value specially, the motor noise can be reduced. Therefore, reduction in the motor noise can be realized without specially increasing the cost of the ball bearing. Now, FIG. 8 shows a third example of a mode for carrying out the invention. According to the present mode, a ball bearing 1a, similarly to the conventionally known ball bearing 1 that is shown in the above-mentioned FIG. 5, comprises an outer ring 3c including on the inner peripheral surface thereof a deep-groove type of outer ring raceway 2c having an arc-shaped section, an inner ring 5c including on the outer peripheral surface thereof an inner ring raceway 4c having an arc-shaped section, and a plurality of balls 6 respectively interposed between the outer and inner ring raceways 2c and 4c so as to be free to roll. These balls 6 are respectively held by a retainer 7 in such a manner that they are able to roll while they are spaced from one another. Also, to the inner peripheral surfaces of the two end portions of the outer ring 3c, there are secured the outer peripheral edge portions of sealed rings 8 and 8, while the inner peripheral edge portions of the sealed rings 8 and 8 are respectively disposed so as to be close to but opposed to the outer peripheral surfaces of the two end portions of the inner ring 5c. Especially, in the case of the ball bearing 1c according to the invention, where the diameter of the respective balls 6 is expressed as Db, the radius of curvature of the section shape of the outer ring raceway 2c is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway 4c is expressed as Ri, the following equations (1) and (2) can be satisfied: that is, 0.58≦Ro/Db≦0.61 (1) 0.52≦Ri/Db≦0.61 (2) In case where the above-structured ball bearing 1a is used to support the rotary shaft of a fan motor for a suction device employed in an electric cleaner, the outer ring 3c is inserted into and fixed to a fixed housing, while the inner ring 5c is outserted and fixed to the rotary shaft. By the way, the ball bearing 1c according to the invention is a ball bearing which not only is used to support the rotary shaft of a blower of a domestic-use electric cleaner but also is used under the low-load and high-speed rotation condition. Referring more specifically to the size of the ball bearing 1c, the outside diameter D of the outer ring 3c is of the order of 15-40 m, the inside diameter d of the inner ring 5c is of the order of 6-18 mm, and the width B of the ball bearing 1c is of the order of 5-12 mm. In the case of the above-structured ball bearing 1c according to the invention, not only sufficient durability can be secured but also, without reducing the outside diameter of the outer ring specially, sufficient rotation torque reduction can be realized. That is, by satisfying the above equations (1) and (2), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls 6 and the outer ring and inner ring raceways 2c, 4c, can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing 1c. Now, description will be given below of the results of a test conducted in order to confirm the effects of the second aspect of the invention. The test was conducted using a deep-groove type of ball bearing in which the outside diameter D of an outer ring 3c is 22 mm, the inside diameter d of an inner ring 5c is 8 mm, and the width of the ball bearing is 7 mm. As will be described below, there were prepared two kinds of embodiments falling within the technical scope of the invention and two kinds of comparison examples not falling within the technical scope of the invention, that is, a total of four kinds of samples. The outer ring 3c, inner ring 5c and balls 6 are all made of steel SUJ2. Embodiment 1 Ro/Db=0.58 Ri/Db=0.58 Embodiment 2 Ro/Db=0.61 Ri/Db=0.61 COMPARISON EXAMPLE 1 Ro/Db=0.56 Ri/Db=0.51 COMPARISON EXAMPLE 2 Ro/Db=0.56 Ri/Db=0.56 Now, in the test, using the above-mentioned four kinds of samples, the influences of the radius of curvature Ro of the section shape of the outer ring raceway 2c and the radius of curvature Ri of the section shape of the inner ring raceway 4c on the rotation torque of the ball bearing were confirmed by the test apparatus 9 as shown in FIGS. 4(A) and 4(B). The test apparatus 9 comprises a rotary shaft 10 and a housing 11 which are disposed concentric with each other. In measuring the rotation torque of the ball bearing, between the outer peripheral surface of the rotary shaft 10 and the inner peripheral surface of the housing 11, there were assembled ball bearings 1c, 1c having the same specifications, the rotary shaft 10 was rotated, and the torque, which was applied to the leading end portion of an arm 12 fixed to the outer peripheral surface of the housing 11, was measured by a load sensor 13. By the way, in all of the samples, grease for lubrication was charged into the ball bearings 1c, 1c, the two end portions of the ball bearings 1c, 1c were sealed by sealed rings 8, 8 each of a non-contact type (see FIG. 8). Also, the test apparatus was operated at room temperature in the air. Further, a preload of 49 N (5 kgf) was applied to the ball bearings 1c, 1c by a spring 14. The rotation speed of the rotary shaft 10 was varied in the range of 40,000-60,000 min−1 and the rotation torque of the ball bearing after the passage of ten minutes from the start of the operation of the test apparatus was measured for every rotation speed. The results of the test conducted in this manner were shown in FIG. 9. In FIG. 9, a solid line a shows the test results of the embodiment 1, a broken line b shows the test results of the embodiment 2, a one-dot chained line c shows the test results of the comparison example 1, and a two-dot chained line d shows the test results of the comparison example 2, respectively. As can be seen clearly from FIG. 9, by reducing the values of the ratios of the radiuses of curvature Ro, Ri of the respective raceways to the ball diameter Db, the rotation torque of the ball bearing can be reduced. Since a ball bearing according to the first aspect of the invention is structured and operates in the above-mentioned manner, the present ball bearing can reduce the rotation resistance or rotation torque of the rotation support portions of various machines and apparatus, thereby being able to save energy when operating such machines and apparatus. In addition, since a ball bearing for an electric cleaner according to the second aspect of the invention is structured and operates in the above-mentioned manner, the present ball bearing not only can secure practically sufficient durability but also can reduce the rotation resistance or rotation torque of the rotation support portion of the electric cleaner, thereby being able to save energy when operating such electric cleaner. While there has been described in connection with the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover in the appended claim all such changes and modifications as fall within the true spirit and scope of the invention. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to a ball bearing, and particularly a ball bearing used to support a rotary shaft, which is disposed in a fan motor of an electric cleaner for domestic use or in a blower of an air conditioner for domestic use and is to be rotated at a high speed with a low load, in such a manner that the rotary shaft can be rotated freely with respect to a housing. Conventionally, such a ball bearing 1 as shown in FIG. 11 is widely used to support a rotary shaft, which is disposed in various apparatus, in such a manner that it can be freely rotated with respect to a housing. The ball bearing 1 comprises an outer ring 3 including on the inner peripheral surface thereof a deep-groove type of outer ring raceway 2 having an arc-shaped section, an inner ring 5 including on the outer peripheral surface thereof an inner ring raceway 4 having an arc-shaped section, and a plurality of balls 6 respectively interposed between the outer and inner ring raceways 2 and 4 so as to be free to roll; and, the outer ring 3 , inner ring 5 and balls 6 are all made of bearing steel such as SUJ2 or M50, ceramic, or the like. The balls 6 are respectively held by a retainer 7 in such a manner that they are able to roll while they are spaced from one another. Also, to the inner peripheral surfaces of the two end portions of the outer ring 3 , there are secured the outer peripheral edge portions of sealed rings 8 and 8 , whereas the inner peripheral edge portions of the sealed rings 8 and 8 are respectively disposed so as to be close and opposed to the outer peripheral surfaces of the two end portions of the inner ring 5 . By the way, in the case of the conventional ball bearing 1 , generally, where the diameter of the respective balls 6 is expressed as Db, the radius of curvature of the section shape of the outer ring raceway 2 is expressed as Ro′, and the radius of curvature of the section shape of the inner ring raceway 4 is expressed as Ri′, the following equations are established; that is, 0.50<Ro′Db<0.53, and 0.50<Ri′/Db≦0.52. Also, where the outside diameter of the outer ring 3 is expressed as D, the inside diameter of the inner ring 5 is expressed as d, and the pitch circle diameter (P.C.D.) of the respective balls 6 is expressed as Dp′, the following equation is established; that is, Dp′≈(D+d)/2. In other words, there is employed the equation, that is, Dp′/(D+d)/2≈1, and the respective balls 6 are positioned substantially in the middle of the outer peripheral surface of the outer ring 3 and the inner peripheral surface of the inner ring 5 with respect to the diameter direction of the ball bearing 1 . In case where the above-structured ball bearing 1 is used to support, for example, the rotary shaft of a fan motor disposed in a suction device employed in an electric cleaner, the outer ring 3 is inserted and fixed to a fixed housing, while the inner ring 5 is outserted and fixed to the rotary shaft. The above-mentioned conventional ball bearing 1 has a general-purpose structure which aims for assembly into one of various rotation support portions, but does not prefer to apply under the low-load and high-speed rotation condition, and, therefore, the rotation torque (rotation resistance) thereof is not always low. On the other hand, there has been increasing a demand for reducing the rotary torque of the rotation support portion in order to be able to cope with a rising energy saving tendency in recent years. In view of such circumstances, it is an urgent need to realize a ball bearing which not only provides a small rotation torque but also can be incorporated into the rotation support portion which rotates at a high speed with a low load. As the simplest means for reducing the rotation torque, it can be expected that, as grease to be applied to the portion where the balls 6 are disposed, grease having low viscosity is used. However, there is a limit to the torque reduction that can be realized by reducing the viscosity of the grease and, therefore, in order to be able to realize large torque reduction, it is necessary to change the structure of the ball bearing itself. In case where the rotation torque of the rotation support portion rotating at a high speed with a low load is reduced by changing the specifications of the ball bearing, use of a ball bearing whose diameter and diameter-associated elements are reduced in size (that is, a small-sized ball bearing) can realize rather large torque reduction. However, in this case, it is necessary to reduce the inside diameter of a housing into which the outer ring is inserted and fixed, which unfavorably requires the design change of the remaining component members of the rotation support portion. Also, even in case where the diameter and its associated elements of the ball bearing are simply reduced in size, there still remains a possibility that sufficient torque reduction cannot be realized. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention aims at eliminating the above-mentioned drawbacks found in the conventional ball bearing. Accordingly, it is an object of the invention to provide a ball bearing which not only can realize a low torque structure but also can be assembled to a housing similar to the conventional ball bearing. In attaining the above object, according to a first aspect of the invention, there is provided a ball bearing which, similarly to the above-mentioned conventional ball bearing, comprises an outer ring including on the inner peripheral surface thereof an outer ring raceway having an arc-shaped section; an inner ring including on the outer peripheral surface thereof an inner ring raceway having an arc-shaped section; and, a plurality of balls respectively and interposed rollably between the outer and inner ring raceways. Especially, in the ball bearing according to the invention, where the outside diameter of the outer ring is expressed as D, the inside diameter of the inner ring is expressed as d, the pitch circle diameter of the respective balls is expressed as Dp, the diameter of the groove bottom of an inner ring raceway whose maximum circumferential stress provides (294 MPa) 30 kgf/mm 2 under the condition that, in case where d is in the range 6 -10 mm, the interference of the inner ring is 11 μm and in case where d in the range of more than 10 mm up to 18 mm, the interference of the inner ring is 12 μm, is expressed as Di, x=Db/{(D−d)/2), and y=Dp/{(D+d)/2}, the following equations (1) to (2) can be satisfied, and also the following equation (3) can be preferably satisfied: that is, in-line-formulae description="In-line Formulae" end="lead"? x≧0.3 (1) in-line-formulae description="In-line Formulae" end="tail"? in-line-formulae description="In-line Formulae" end="lead"? y<1.0 (2) in-line-formulae description="In-line Formulae" end="tail"? in-line-formulae description="In-line Formulae" end="lead"? y ≧{( D−d )/( D+d )} x+ 2 Di /( D+d ) (3). in-line-formulae description="In-line Formulae" end="tail"? Also, preferably, where the diameter of the respective balls is expressed as Db, the radius of curvature of the section shape of the outer ring raceway is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway is expressed as Ri, the following equations (4) and (5) can be satisfied: that is, in-line-formulae description="In-line Formulae" end="lead"? 0.53 <Ro/Db ≦0.65 (4) in-line-formulae description="In-line Formulae" end="tail"? in-line-formulae description="In-line Formulae" end="lead"? 0.52 <Ri/Db ≦0.65 (5). in-line-formulae description="In-line Formulae" end="tail"? In the case of the above-structured ball bearing according to the first aspect of the invention, not only sufficient durability can be secured but also sufficient rotation torque reduction can be realized without changing the outside diameter of the outer ring specially. That is, in order to satisfy the equation (2), the plurality of balls are positioned on the inside diameter side of the ball bearing. This can reduce the moment necessary to roll these balls, thereby being able to reduce the rotation torque of the ball bearing. In this manner, even when reducing the rotation torque of the ball bearing, in order to satisfy the equation (1), by securing the diameter Db of the balls, the contact ellipses in the contact portions between the balls and outer ring raceway can be prevented from decreasing in size excessively, which can prevent Brinell impressions from occurring in the outer ring raceway. Further, in order to satisfy the equation (3), by securing the pitch circle diameter Dp of the balls, even when the inner ring is outserted onto the rotary shaft, circumstantial stress occurring in the inner ring can be prevented from increasing excessively, which can prevent the inner ring against damage such as occurrence of a crack. By the way, in the equation (3), the inner ring raceway (groove bottom) surface Di depends on the fit standard js5 specified in JIS and on the strength that is required of the inner ring. That is, according to the js5, the upper limit value of the interference of an inner ring is 11 μm in the case of an inner ring having an inside diameter of 6 -10 mm and, in the case of an inner ring having an inside diameter of 10 -18 mm, it is 12 μm. Further, the outer ring, the inner ring and the plurality of balls are preferably made of bearing steel. Generally, the inner ring raceway surface Di having an influence on the thickness of the groove bottom of the inner ring is specified in such a manner that the maximum stress of bearing steel can be of 137.2 MPa (14 kgf/mm 2 ) or less. However, actually, depending on the selection of the material of the inner ring and on the change of the thermal treatment thereof, up to the stress of 294 Mpa (30 kgf/mm 2 ), the thickness of the groove bottom can be reduced. For this reason, the inner ring raceway surface Di is set at the value where the maximum circumstantial stress provides 294 MPa (30 kgf/mm 2 ) By the way, referring to the ratio R 1 /D b between the diameter D b of each ball and the radius of curvature R 1 of the section shape of the inner ring raceway, as in a fan motor used in a blower of an air conditioning apparatus, when the fan motor is used at a speed of 10,000 min −1 (r.p.m.) or less, the ratio is set such that 0.52<R 1 /D b <0.65; but, as in a fan motor used in a suction device of an electric cleaner, when the fan motor is used at a speed of 20,000 min −1 (r.p.m.) or more, preferably, the ratio may be set such that 0.53<R 1 /D b ≦0.65. Moreover, by satisfying the above equations (4) and (5), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls and the outer ring and inner ring raceways can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing. By the way, in case where the values of Ro/Db and Ri/Db exceed 0.65 and increase excessively, the area of each of the contact ellipses is reduced excessively, which makes it difficult to secure the rolling fatigue lives of the outer and inner ring raceways; and, especially, in the case of the outer ring raceway, Brinell impressions are easy to occur. For these reasons, the upper limit values of Ro/Db and Ri/Db are set at 0.65. In attaining the above object, according to a second aspect of the invention, there is provided a ball bearing for use in an electric cleaner which comprises an outer ring made of bearing steel and including on the inner peripheral surface thereof an outer ring raceway having an arc-shaped section; an inner ring made of bearing steel and including on the outer peripheral surface thereof an inner ring raceway having an arc-shaped section; and, a plurality of balls respectively made of bearing steel and interposed rollably between the outer and inner ring raceways. And, the present electric cleaner ball bearing is incorporated into the rotation support portion of the electric cleaner and is used in such a manner that the outer ring is fixed and the inner ring is rotated at the speed of 40,000-60,000 min −1 (r.p.m). Especially, in the ball bearing according to the second aspect of the invention, where the diameter of the respective balls is expressed as Db, the radius of curvature of the section shape of the outer ring raceway is expressed as Ro, and the radius of curvature of the section shape of the inner ring raceway is expressed as Ri, the following equations (1) and (2) can be satisfied: that is, in-line-formulae description="In-line Formulae" end="lead"? 0.58 ≦Ro/Db≦ 0.61 (1) in-line-formulae description="In-line Formulae" end="tail"? in-line-formulae description="In-line Formulae" end="lead"? 0.52 ≦Ri/Db≦ 0.61 (2) in-line-formulae description="In-line Formulae" end="tail"? In the case of the above-structured ball bearing for an electric cleaner according to the second aspect of the invention, not only sufficient durability can be secured but also sufficient rotation torque reduction can be realized without reducing the outside diameter of the outer ring specially. That is, by satisfying the above equations (1) and (2), contact ellipses, which are formed in the contact portions between the rolling surfaces of the balls and the outer ring and inner ring raceways, can be reduced in size so that rolling resistance and spin, which are caused in the contact ellipse portions during rotation, can be reduced to thereby be able to reduce the rotation torque of the ball bearing. By the way, the reason why, as described above, the ratios of the radius of curvature of the section shape of the outer ring raceway Ro and the radius of curvature of the section shape of the inner ring raceway Ri to the diameter of the respective balls Db are respectively set in the range of 58-61% is as follows. That is, as these ratios increase, the contact ellipses formed in the respective contact portions decrease in size, thereby being able to reduce the rotation torque of the ball bearing. Therefore, in order to reduce the rotation torque of the ball bearing, it is preferred to increase these ratios (that is, Ro/Db and Ri/Db). On the other hand, in case where these ratios are increased, the surface pressures of the respective contact portions increase, which lowers the exfoliation lives of the outer ring raceway and inner ring raceways. Here, FIG. 10 shows the relation between the above ratios and the exfoliation lives of the outer and inner raceways under the operation conditions (rotation speed=60,000 min −1 (r.p.m.), and preload of 49 N (5 kgf)} of a ordinary electric cleaner ball bearing (the outside diameter D of an outer ring=22 mm, the inside diameter d of an inner ring=8 mm, and the width B of the ball bearing=7 mm). As can be seen clearly from FIG. 10 , Generally, when the durability of the rotation support portion is taken into account, it is not expedient to form outer and inner ring raceways having such large radiuses of curvature that provide the ratios (that is, Ro/Db and Ri/Db) of more than 56%. On the other hand, as in an electric cleaner ball bearing to which the present invention relates, when a ball bearing is used under the conditions that the rotation portion is rotated at a high speed with a low load and dust such as brush friction powder can invade into the interior portion of the ball bearing, the life of the ball bearing depends, in many cases, on the occurrence of seizure rather than on the coming of the exfoliation life. And, due to the enhanced speed of the rotation of the rotation support portion, in many cases, such seizure occur in the range of 2,000-3,000 hours. Therefore, it is no expedient that, in order to obtain an exfoliation life which exceeds greatly 2,000-3,000 hours, the above ratios are reduced (that is, the ratios are approximated to 50%), because this increases the rotation torque of the ball bearing. When such circumstances are taken into consideration, in case where the above ratios are respectively set in the range of 58-61%, not only a practically sufficient exfoliation life can be secured but also the rotation torque of the ball bearing can be reduced to a sufficient degree. | 20040402 | 20060718 | 20050407 | 57701.0 | 0 | SICONOLFI, ROBERT | BALL BEARING | UNDISCOUNTED | 1 | CONT-ACCEPTED | 2,004 |
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10,816,089 | ACCEPTED | Slim spacer device and manufacturing method | A CMOS structure including a Slim spacer and method for forming the same to reduce an S/D electrical resistance and improve charge mobility in a channel region, the method including providing a semiconductor substrate including a polysilicon gate structure including at least one overlying hardmask layer; forming spacers selected from the group consisting of oxide/nitride and oxide/nitride oxide layers adjacent the polysilicon gate structure; removing the at least one overlying hardmask layer to expose the polysilicon gate structure; carrying out an ion implant process; carrying out at least one of a wet and dry etching process to reduce the width of the spacers; and, forming at least one dielectric layer over the polysilicon gate structure and spacers in one of tensile and compressive stress. | 1. a semiconductor device comprising: a substrate having a surface orientation of (100); a gate electrode formed on the substrate; a Slim spacer formed on the top of the substrate source-to-drain axis is formed along the <100> 2. The semiconductor device of claim 1, wherein the width of the Slim spacer is less than about 500 Angstroms. 3. The semiconductor device of claim 1, wherein the polysilicon gate structure comprises a gate length of less than about 80 nanometers. 4. The semiconductor device of claim 1, forming at least one dielectric layer over the polysilicon gate structure and spacers in tensile stress. 5. The semiconductor device of claim 4, wherein the tensile-stress film exerts a tensile stress of a magnitude of about 50 MPa to about 2 GPa. 6. A method for forming a Slim spacer adjacent a CMOS gate structure comprising the steps of: providing a semiconductor substrate comprising a gate structure including at least one overlying hardmask layer; forming dielectric spacers adjacent the gate structure; carrying out an ion implant process; carrying out at least one of a wet and dry etching process to reduce the width of the spacers; and, forming at least one dielectric layer over the gate structure and spacers in one of tensile and compressive stress to form a stress level in a channel region. 7. The method of claim 1, wherein dielectric layer comprises compressive stress to enhance PMON drive current. 8. The method of claim 1, wherein dielectric layer comprises tensile stress to enhance NMON drive current. 9. The method of claim 1, wherein dielectric layer comprises tensile stress to enhance NMON drive current. 10. The method of claim 1, further comprising forming salicides adjacent the spacers and over the polysilicon gate structure prior to the step of forming at least one dielectric layer. 11. The method of claim 1, wherein the width of the spacers is reduced by an amount greater than about 20 percent. 12. The method of claim 1, wherein the width of the spacers is reduced to have a final width less than about 500 Angstroms. 13. The method of claim 1, wherein the width of the spacers is reduced to have a final width less than about 400 Angstroms. 14. The method of claim 1, wherein the polysilicon gate structure comprises a gate length of less than about 80 nanometers. 15. The method of claim 1, further comprising the step of annealing the polysilicon gate structure to recrystallize amorphous portions and increase one of a compressive and tensile stress in the channel region. 16. The method of claim 7, wherein the at least one dielectric layer is removed to leave an increased stress level in the channel region. 17. The method of claim 1, wherein the oxide comprises silicon oxide formed by a CVD process. 18. The method of claim 1, wherein the nitride is selected from the group consisting of silicon nitride and silicon oxynitride formed by a CVD process. 19. The method of claim 1 wherein the at least one hardmask layer comprises a lowermost oxide layer and an uppermost nitride layer. 20. The method of claim 1, wherein the at least one dielectric layer is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and silicon oxycarbide. 21. A CMOS structure having a reduced S/D electrical resistance and increased charge carrier mobility in a channel region comprising: a semiconductor substrate; a gate structure formed overlying the semiconductor substrate comprising a polysilicon electrode; spacers adjacent either side of the polysilicon electrode comprising an oxide/nitride portion adjacent the polysilicon electrode; and, wherein source/drain extension (SDE) regions comprising the semiconductor substrate extend beyond a maximum width of the spacers. 22. The CMOS structure of claim 25, further comprising at least one dielectric layer in one of tensile and compressive stress overlying the gate structure and spacers. 23. The CMOS structure of claim 26, wherein the at least one dielectric layer is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and silicon oxycarbide. 24. The CMOS structure of claim 25, further comprising salicide portions comprising a portion of the SDE doped regions. 25. The CMOS structure of claim 25, wherein the gate length is less than about 80 nm. 26. The CMOS structure of claim 25, wherein the maximum width of the spacers is less than about 500 Angstroms. 27. The CMOS structure of claim 25, wherein the maximum width of the spacers is less than about 400 Angstroms. 28. The CMOS structure of claim 25, wherein the oxide portion comprises CVD silicon oxide. 29. The CMOS structure of claim 25, wherein the nitride portion is selected from the group consisting of CVD silicon nitride and CVD silicon oxynitride. 30. The CMOS structure of claim 25, wherein the spacers comprises substantially vertical sidewalls. 31. A CMOS structure having a reduced S/D electrical resistance and increased charge carrier mobility in a channel region comprising: a semiconductor substrate; a gate structure overlying the semiconductor substrate comprising a polysilicon electrode; spacers adjacent either side of the polysilicon electrode comprising an oxide portion adjacent the polysilicon electrode and a nitride portion adjacent the oxide portion; wherein a maximum width of the spacers is such that a portion of underlying source/drain extension (SDE) doped regions in the semiconductor substrate are exposed; and, salicide portions extending into a portion of the SDE doped regions. 32. The CMOS structure of claim 35, further comprising at least one dielectric layer overlying the gate structure and spacers in one of tensile and compressive stress. 33. The CMOS structure of claim 36, wherein the at least one dielectric layer is selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and silicon oxycarbide. 34. The CMOS structure of claim 35, wherein the gate length is less than about 80 nm. 35. The CMOS structure of claim 35, wherein the maximum width of the spacers is less than about 500 Angstroms. 36. The CMOS structure of claim 35, wherein the maximum width of the spacers is less than about 400 Angstroms. 37. The CMOS structure of claim 35, wherein the oxide portion comprises CVD silicon oxide. 38. The CMOS structure of claim 35, wherein the nitride portion is selected from the group consisting of CVD silicon nitride and CVD silicon oxynitride. 39. The CMOS structure of claim 35, wherein the spacers comprises substantially vertical sidewalls. | FIELD OF THE INVENTION This invention generally relates to processes for forming semiconductor devices including CMOS and MOSFET devices and more particularly to a CMOS device and method for forming the same having a Slim spacer with improved electrical performance including reduced short channel effects and increased charge carrier mobility. BACKGROUND OF THE INVENTION As MOSFET and CMOS device characteristic sizes are scaled below 0.25 microns including below 0.1 micron, the device designs need to be modified for each generation of device scaling down. For example, short channel effects (SCE) are one of the most important challenges for designers to overcome as device critical dimensions are scaled down. Among the many manifestations of SCE, are Voltage threshold (VT) rolloff, drain induced barrier lowering (DIBL), and subthreshold swing variation. Source/Drain (S/D) junction depth and channel doping are some of the few parameters that can be changed to reduce SCE. Since the source drain extension (SDE) implants are self-aligned to the gate edge, the junction depth of the S/D regions is typically scaled to the gate length (LG). One problem with reducing junction depth is the effect of increasing the S/D region sheet resistance, which reduces drive current (ID). One approach to reducing the increase in S/D sheet resistance with shallower junction depths is to form salicides over the S/D regions. However, the width of spacers which mask an underlying lightly doped regions also referred to as source drain extension (SDE) regions during a S/D implant process have the effect of reducing the amount of salicide that may be formed over the S/D and SDE regions. Therefore, while it may be desirable to have a desired spacer width and a desired underlying SDE region width, the spacer width limits the degree of lowering the sheet resistance of the S/D region by salicide formation leading to lower drive current (ID). In addition, as gate lengths become smaller, for example less than about 80 nanometers, conventional processes for forming spacers are no longer adequate to precisely position the S/D implant regions, thereby leading to increased SCE. In some approaches in the prior art, disposable spacers have been proposed to address the problem of having a desirable spacer width to form a desired S/D region and subsequent salicide width to lower S/D region sheet resistance. Among the shortcomings of disposable spacers includes costly and complicated processes requiring extra process steps which undesirably decreases throughput and adds to cost. In addition, disposable spacers lead to reduced control in forming a selected level of tensile or compressive stresses in the channel region to achieve improved charge mobility. There is therefore a need in the semiconductor integrated circuit manufacturing art for an improved method for forming dielectric spacers to achieve desired dimensions while reducing S/D region electrical resistance and associated SCE effects while increasing charge mobility at acceptable process throughput and process cost. It is therefore among the objects of the present invention to provide an improved method for forming dielectric spacers to achieve desired dimensions while reducing S/D region electrical resistance and associated SCE effects while increasing charge mobility at acceptable process throughput and process cost, as well as overcoming other shortcomings of the prior art. In another approach, strain in the channel is introduced after the transistor is formed. In this approach, a high stress film is formed over a completed transistor structure formed in a silicon substrate. The high stress film or stressor exerts significant influence on the channel, modifying the silicon lattice spacing in the channel region, and thus introducing strain in the channel region. In this case, the stressor is placed above the completed transistor structure. This scheme is described in detail in a paper by A. Shimizu et al., entitled “Local mechanical stress control (LMC): a new technique for CMOS performance enhancement,” published in pp. 433-436 of the Digest of Technical Papers of the 2001 International Electron Device Meeting, which is incorporated herein by reference. SUMMARY OF THE INVENTION To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides a CMOS structure comprising a Slim spacer and method for forming the same to reduce an S/D electrical resistance and improve charge mobility in a channel region. In a first embodiment, the method includes providing a semiconductor substrate including a polysilicon or metal gate structure including at least one overlying hardmask layer; forming spacers selected from the group consisting of oxide/nitride and oxide/nitride oxide layers adjacent the polysilicon or metal gate structure; removing the at least one overlying hardmask layer to expose the polysilicon or metal gate structure; carrying out an ion implant process; carrying out at least one of a wet and dry etching process to reduce the width of the spacers; and, forming at least one dielectric layer over the polysilicon or metal gate structure and spacers in one of tensile and compressive stress. In one embodiment of the present invention, a semiconductor device is provided on a substrate having a <100> crystal orientation. Current flow of device is along <100> direction. The mobility of PMOS could be enhanced on this direction. These and other embodiments, aspects and features of the invention will be better understood from a detailed description of the preferred embodiments of the invention which are further described below in conjunction with the accompanying Figures. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1F are cross sectional views including a portion of a gate structure of an exemplary MOSFET showing exemplary manufacturing stages in an integrated circuit manufacturing process according to an embodiment of the present invention. FIGS. 2A-2D are cross sectional views including a portion of a gate structure of an exemplary MOSFET showing exemplary manufacturing stages in an integrated circuit manufacturing process according to an embodiment of the present invention. FIG. 3 is a data representation showing the gain in channel stress achieved according to the Slim spacer MOSFET device formed according to embodiments of the present invention. FIG. 4 is a process flow diagram including several embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the method of the present invention is explained by reference to exemplary device sizes and is most advantageously used with preferred devices sizes, including spacer widths and gate lengths, it will be appreciated that the method of the present invention may be used with other device sizes as well. Referring to FIGS. 1A-1F is shown an exemplary implementation of the method of the present invention. Shown are a silicon or silicon germanium substrate 10, an overlying gate dielectric layer (such as oxide) portion 12, and an overlying polysilicon or metal gate electrode portion 14. In an aspect of the invention, at least one hardmask layers are deposited over a polysilicon or metal layer prior to forming the gate structure to form hardmask layer portions 16A and 16B overlying gate electrode portion 14 by conventional deposition, photolithographic and etching processes. For example the lowermost hardmask layer 16A is preferably formed of silicon oxide, e.g., LPCVD or PECVD silicon oxide and hardmask layer 16B is preferably formed of silicon nitride and/or silicon oxynitride by conventional LPCVD or PECVD processes, for example the two hardmask layer portions 16A and 16B having a total thickness of about 300 Angstroms to about 1000 Angstroms. It will be appreciated that a conventional source/drain extension (SDE) ion implant process may be carried prior to or following removal of the hardmask layer portion 16B to form SDE regions e.g., 20A, 20B as explained below. Referring to FIG. 1B, in an aspect of the invention, the uppermost hardmask layer e.g., 16B is removed by a conventional wet or dry etching process to leave the lowermost hardmask layer portion e.g., 16A overlying the polysilicon or metal electrode portion 14. Referring to FIG. 1C, in one embodiment of the invention, an oxide layer, for example LPCVD TEOS oxide is first blanket deposited, for example having a thickness less than about 200 Angstroms, more preferably less than about 150 Angstroms, followed by deposition of a nitride layer, for example silicon nitride or silicon oxynitride (e.g., SiON), preferably silicon nitride, (e.g., Si3N4, SiN), preferably by an LPCVD process and preferably having a thickness of greater than about 450 Angstroms. A conventional wet and/or dry etchback process is then carried out to etch through a thickness of the nitride layer and underlying oxide layer to stop on the hardmask portion 16A to form nitride spacer portion e.g., 18A and oxide spacer portion e.g., 18B adjacent either side of the gate structure. Referring to FIG. 1D, in an important aspect of the invention, a conventional wet or dry etching process, preferably a wet oxide (isotropic) etch process is then carried out, for example using dilute HF and an optional buffer agent, to remove the oxide hardmask layer portion 16A overlying the polysilicon or metal electrode portion 14. It will be appreciated that in an isotropic wet etch process a portion of the oxide spacer portion 18A will be removed as well, preferably to be about co-planar with the polysilicon or metal electrode 14 upper portion, while removing a portion underling the nitride portion 18B. Following removal of the hardmask layer portion 16A overlying the polysilicon or metal electrode portion 14, a conventional S/D ion implantation process, also referred to as a high dose implant (HDI) is then carried out to dope the polysilicon electrode or metal portion 14 as well as form the S/D regions e.g., 22a, 22B adjacent the SDE regions e.g., 20A, 20B. Referring to FIG. 1E, in a critical aspect of the invention, a wet or dry etching process is then carried out to remove a portion of the nitride spacer 18B, to form a Slim (reduced width) oxide/nitride spacer width from W2 to W1. Advantageously, in the spacer thinning process a portion of the underlying SDE region e.g., 20A is exposed by the reduced width amount e.g., W3. For example, a maximum width W1 of the Slim spacers is preferably less than a width W2 of the SDE doped regions e.g., 20A measured to an edge of the S/D doped region 22A. It will be appreciated that the desired reduction in width of the nitride spacer portion 18B will vary depending on the gate length and the oxide/nitride spacer width W2 present for the S/D implant process prior to thinning, a desired reduction in S/D resistance, and a desired increase in channel stress. Preferably, however, the Slim width W1 of the oxide/nitride spacer 18A and 18B measured from the polysilicon or metal gate electrode sidewall 14, is reduced by greater than about 20 percent of W2 to achieve a desired electrical resistance decrease in S/D region e.g., 22A and SDE region e.g., 20A and/or an increase in channel stress in channel region e.g., 26. In an exemplary embodiment, for a CMOS gate structure having a gate length (LG), of about 400 Angstroms and a pre-Slim spacer width W2 of about 650 Angstroms, the spacer is reduced to a width W1 of less than about 500 Angstroms, more preferably less than about 350 Angstroms. Still referring to FIG. 1E, following the wet or dry etching process to reduce the spacer width, optionally a salicide formation process is undertaken by conventional processes to form salicide regions e.g., 24A and 24B respectively over the S/D regions e.g., 22A and 22B and a portion of exposed SDE regions e.g., 20A, 20B as well as over the upper portion e.g., 14A of polysilicon electrode 14. Preferably the salicide regions are formed of TiS2, CoSi2 or NiSi by conventional process of depositing Ti, Co or Ni over exposed silicon and polysilicon or metal portions followed by a subsequent annealing process as is known in the art to form the low resistance phase of the respective salicide. Less preferably, the salicide formation process may be carried out subsequent to the stressed dielectric formation and removal process outlined below. Advantageously, according to the present invention, by exposure of a portion of the underlying SED regions e.g., 20A in the spacer width reduction process, and subsequent formation of an overlying salicide portion e.g., 24A, the electrical resistance of the S/D regions e.g., 22A and SDE regions e.g., 20A are reduced, thereby allowing reduced gate length and reduced S/D and SDE junction depths to reduced short channel effects (SCE) while increasing the drive current (Id). For example, the electrical operating characteristics e.g., IDsat of MOSFET devices having gate lengths (LG) of 80 nanometers or less are advantageously improved without accompanying SCE, according to embodiments of the present invention. Referring to FIG. 1F, in a related embodiment of the invention, a stressed dielectric layer 28 in one of tensile or compressive stress is then formed (e.g., blanket deposited) over the gate structure including the S/D regions and SDE regions. For example, the stressed dielectric layer 28 is preferably formed in tensile stress for a NMOS device and preferably formed in compressive stress for a PMOS device. It will be appreciated that the level of the tensile or compressive stress can be varied by a number of factors including the thickness of the stressed dielectric layer 28, preferably being from about 50 Angstroms to about 1000 Angstroms in thickness up to about a 2 GPa respective stress level. Preferably, the stressed dielectric layer 28 is deposited by a CVD process where the relative reactant flow rates, deposition pressure, and temperature may be varied to vary a composition of the dielectric layer thereby controlling the level of either tensile or compressive stress. For example, stressed dielectric layer 28 may be a nitride or carbide, such as silicon nitride (e.g., SiN, SixNy), silicon oxynitride (e.g., SixONy), or silicon carbide (e.g., SixOCy) where the stoichiometric proportions x and y may be selected according to CVD process variables as are known in the art to achieve a desired tensile or compressive stress in a deposited dielectric layer. For example, the CVD process may be a low pressure chemical vapor deposition (LPCVD) process, an atomic layer CVD (ALCVD) process, or a plasma enhanced CVD (PECVD) process. The stressed dielectric layer 28 may be removed or left in place following a subsequent annealing process where amorphous portions of the polysilicon are recrystallized thereby increasing a selected stress level on the channel region e.g., 26 to improve carrier mobility. Referring to FIG. 3, advantageously, according to the present invention, the selected amount of stress in the channel region can be increased significantly by reduction of spacer width according to preferred embodiments. For example, shown is a data representation of a CMOS device formed with a reduced spacer width according to embodiments of the present invention. Shown on the vertical axis is a ratio of channel stress to dielectric layer stress (e.g. 28) and on the horizontal axis is shown an spacer width formed according to preferred embodiments. Data lines A, B and C represent respective spacer widths formed for a CMOS device having respective 25 nm, 40 nm, and 80 nm gate lengths. Data to the left of line A1 (shown by directional arrow A2) represent reduced spacer widths with increased channel stress for a given dielectric layer stress according to embodiments of the present invention. It is seen that the ratio of channel stress to dielectric layer stress (vertical axis) increases with reduced spacer width, for example increasing by up to about 60% at line B1. Therefore, advantageously, an increased level of channel stress can be formed for a given stress level of the dielectric layer following reduced spacer width formation according to embodiments of the present invention. Formation of salicides advantageously further adds to increased channel stress while reducing S/D and SDE region electrical resistance. The increased stress in the channel region together is salicide formation increases charge carrier mobility while reducing short channel effects (SCE) and increasing drive current (ID) at smaller gate lengths. Referring back to FIG. 2A, is shown another embodiment of the present invention. In this embodiment, the formation steps including formation of two hardmask layers 16A and 16B followed by removal of the uppermost hardmask layer 16B, and formation of SDE region e.g., 20A and 20B are the same as outlined with respect to the embodiment shown in FIGS. 1A and 1B. Still referring to FIG. 2A, in the present embodiment, oxide/nitride/oxide spacers are formed of the same preferred materials outlined for the oxide/nitride spacers in the embodiment shown in FIG. 1, but additionally including deposition of an uppermost oxide layer to form oxide portion e.g., 18C following conventional wet and/or dry etchback process. The maximum width WB1 of the oxide/nitride/oxide spacers prior to width reduction as measured from the polysilicon or metal electrode 14 sidewall portion is for example, greater than about 450 Angstroms. Referring to FIG. 2B, a conventional oxide wet or dry etching process, preferably an isotropic wet etch process, is first carried out to remove the hardmask layer 16A oxide hardmask layer over the polysilicon electrode 14 as well as removing portions of the spacer oxide portions 18A and 18C. Preferably the oxide portions are removed to a desired reduction in width of the oxide/nitride/oxide spacers e.g., WB1 to WB2. A high dose implant (HDI) process is then carried out to dope the polysilicon or metal gate electrode 14 as well as forming the S/D regions e.g., 22A and 22B. It will be appreciated that amorphous polysilicon regions may be formed in the polysilicon or metal electrode portion 14 during the HDI process. Referring to FIG. 2C, the nitride portion e.g., 18B of spacer width WB1 is then reduced by a conventional nitride wet or dry etch to form reduced oxide/nitride/oxide spacer width WB2, preferably less than about 500 Angstroms in width, more preferably less than about 400 Angstroms in width, measured at a maximum width of the spacer from the polysilicon or metal gate sidewall. Advantageously, in the spacer thinning process a portion of the underlying SDE region e.g., 20A is exposed, for example an exposed width of the underlying SDE region being about equal to the amount by which the spacer width is Slim. Referring to FIG. 2D, a conventional oxide wet etch process for example a dip in dilute HF is then carried out to remove remaining portions of the oxide portion e.g., 18C of the spacer, including any oxide portions overlying the silicon substrate 10 to form oxide/nitride spacers having substantially vertical sidewall portions e.g., oxide/nitride portions 18A and 18B. A salicide formation process is then preferably carried out by the same process as previously outlined to form salicide regions e.g., 24A , 24B, and 14A in the same manner as previously outlined in FIG. 1E, advantageously extending into a portion of the SDE region e.g., 20A. Referring to FIG. 2E, a stressed dielectric layer 28, optionally including an underlying oxide buffer layer, is then deposited, annealed, and subsequently optionally removed to form a stressed channel region e.g., 26 in the same manner and according to the same preferred embodiments as outlined above for FIG. 1F. Thus, a method for producing reduced width spacers in a CMOS device manufacture process has been presented that allows adjustable control over the width of the spacer prior to forming an overlying stressed dielectric layer and salicide portions. Advantageously, the width of the spacer may be selected to achieve a desired electrical resistance over the S/D and SDE regions as well as achieving a desired increase in compressive or tensile stress in the channel region. The method is cost effective since the number of required steps is limited and the process uses conventional materials and etching processes. Referring to FIG. 4 is a process flow diagram including several embodiments of the present invention. In process 401, a silicon substrate including a CMOS gate structure is provided with SDE doped portions and a double layer hardmask layer overlying the polysilicon or metal electrode portion. In process 403, the uppermost hardmask layer is removed. In process 405, an oxide/nitride or oxide/nitride/oxide spacer is formed. In process 407, the lowermost hardmask layer is removed. In process 409 a high dose implant (HDI) process is carried out to dope the polysilicon layer and form S/D regions. In process 411, the spacers are Slim (width reduced) to a predetermined width according to preferred embodiments. In optional process 413, salicides are formed over S/D regions including SDE regions and the uppermost polysilicon or metal electrode portion. In process 415 a stressed dielectric layer is formed over the CMOS gate structure including Slim spacers. In process 417, an annealing process is carried out to recrystallize amorphous polysilicon or metal electrode portions to create a predetermined stress type (tensile or compressive) and stress level in the channel region underlying the CMOS polysilicon or metal gate structure. The preferred embodiments, aspects, and features of the invention having been described, it will be apparent to those skilled in the art that numerous variations, modifications, and substitutions may be made without departing from the spirit of the invention as disclosed and further claimed below. | <SOH> BACKGROUND OF THE INVENTION <EOH>As MOSFET and CMOS device characteristic sizes are scaled below 0.25 microns including below 0.1 micron, the device designs need to be modified for each generation of device scaling down. For example, short channel effects (SCE) are one of the most important challenges for designers to overcome as device critical dimensions are scaled down. Among the many manifestations of SCE, are Voltage threshold (VT) rolloff, drain induced barrier lowering (DIBL), and subthreshold swing variation. Source/Drain (S/D) junction depth and channel doping are some of the few parameters that can be changed to reduce SCE. Since the source drain extension (SDE) implants are self-aligned to the gate edge, the junction depth of the S/D regions is typically scaled to the gate length (L G ). One problem with reducing junction depth is the effect of increasing the S/D region sheet resistance, which reduces drive current (I D ). One approach to reducing the increase in S/D sheet resistance with shallower junction depths is to form salicides over the S/D regions. However, the width of spacers which mask an underlying lightly doped regions also referred to as source drain extension (SDE) regions during a S/D implant process have the effect of reducing the amount of salicide that may be formed over the S/D and SDE regions. Therefore, while it may be desirable to have a desired spacer width and a desired underlying SDE region width, the spacer width limits the degree of lowering the sheet resistance of the S/D region by salicide formation leading to lower drive current (I D ). In addition, as gate lengths become smaller, for example less than about 80 nanometers, conventional processes for forming spacers are no longer adequate to precisely position the S/D implant regions, thereby leading to increased SCE. In some approaches in the prior art, disposable spacers have been proposed to address the problem of having a desirable spacer width to form a desired S/D region and subsequent salicide width to lower S/D region sheet resistance. Among the shortcomings of disposable spacers includes costly and complicated processes requiring extra process steps which undesirably decreases throughput and adds to cost. In addition, disposable spacers lead to reduced control in forming a selected level of tensile or compressive stresses in the channel region to achieve improved charge mobility. There is therefore a need in the semiconductor integrated circuit manufacturing art for an improved method for forming dielectric spacers to achieve desired dimensions while reducing S/D region electrical resistance and associated SCE effects while increasing charge mobility at acceptable process throughput and process cost. It is therefore among the objects of the present invention to provide an improved method for forming dielectric spacers to achieve desired dimensions while reducing S/D region electrical resistance and associated SCE effects while increasing charge mobility at acceptable process throughput and process cost, as well as overcoming other shortcomings of the prior art. In another approach, strain in the channel is introduced after the transistor is formed. In this approach, a high stress film is formed over a completed transistor structure formed in a silicon substrate. The high stress film or stressor exerts significant influence on the channel, modifying the silicon lattice spacing in the channel region, and thus introducing strain in the channel region. In this case, the stressor is placed above the completed transistor structure. This scheme is described in detail in a paper by A. Shimizu et al., entitled “Local mechanical stress control (LMC): a new technique for CMOS performance enhancement,” published in pp. 433-436 of the Digest of Technical Papers of the 2001 International Electron Device Meeting, which is incorporated herein by reference. | <SOH> SUMMARY OF THE INVENTION <EOH>To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides a CMOS structure comprising a Slim spacer and method for forming the same to reduce an S/D electrical resistance and improve charge mobility in a channel region. In a first embodiment, the method includes providing a semiconductor substrate including a polysilicon or metal gate structure including at least one overlying hardmask layer; forming spacers selected from the group consisting of oxide/nitride and oxide/nitride oxide layers adjacent the polysilicon or metal gate structure; removing the at least one overlying hardmask layer to expose the polysilicon or metal gate structure; carrying out an ion implant process; carrying out at least one of a wet and dry etching process to reduce the width of the spacers; and, forming at least one dielectric layer over the polysilicon or metal gate structure and spacers in one of tensile and compressive stress. In one embodiment of the present invention, a semiconductor device is provided on a substrate having a <100> crystal orientation. Current flow of device is along <100> direction. The mobility of PMOS could be enhanced on this direction. These and other embodiments, aspects and features of the invention will be better understood from a detailed description of the preferred embodiments of the invention which are further described below in conjunction with the accompanying Figures. | 20040331 | 20070116 | 20051013 | 63418.0 | 1 | PIZARRO CRESPO, MARCOS D | SLIM SPACER DEVICE AND MANUFACTURING METHOD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,189 | ACCEPTED | Lithographic apparatus and device manufacturing method | A lithographic apparatus for immersion lithography is described in which a compensation controller controls actuators to apply forces to the substrate equal in magnitude and opposite in direction to forces which are applied to the substrate by a liquid supply system which supplies liquid between the projection system and the substrate. | 1. A lithographic apparatus comprising: an illumination system configured to provide a beam of radiation; a support structure configured to hold a patterning device, the patterning device configured to impart the beam with a pattern in its cross-section; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; a liquid supply system configured to provide an immersion liquid between the projection system and the substrate table; an actuator configured to apply a force to the substrate; and a compensation controller configured to determine a compensating force to be applied by the actuator to the substrate to be substantially equal in magnitude and substantially opposite in direction to a force applied to the substrate by the liquid supply system. 2. Apparatus according to claim 1, wherein the compensation controller is configured to determine the compensation force in a feed-forward manner. 3. Apparatus according to claim 1, wherein the compensation controller is configured to determine the compensation force in a feedback manner. 4. Apparatus according to claim 1, wherein the compensation controller is configured to determine a compensation force that is filtered and corrected for dynamic properties of the liquid supply system. 5. Apparatus according to claim 1, wherein the compensation controller is configured to determine the compensation force based on an actual or a desired position of the substrate. 6. Apparatus according to claim 1, wherein the compensation controller is configured to control the actuator to apply a compensating force on the substrate table substantially equal in magnitude and substantially opposite in direction to a force applied to the substrate table by the liquid supply system. 7. Apparatus according to claim 1, wherein the compensation controller is configured to determine the compensation force based on a force applied to the substrate by the liquid supply system due to gravity. 8. Apparatus according to claim 1, wherein the liquid supply system comprises a barrier member at least partly surrounding the projection system to define a space between the projection system and the substrate to be at least partially filled with an immersion liquid. 9. Apparatus according to claim 8, wherein the barrier member is at least partly supported by the substrate, the substrate table, or both. 10. Apparatus according to claim 8, comprising a barrier actuator configured to position the barrier member in a direction substantially parallel to the optical axis of the projection system. 11. Apparatus according to claim 10, wherein the barrier actuator is a gas bearing, a hydrodynamic bearing or a hydrostatic bearing. 12. Apparatus according to claim 10, wherein the compensation controller is configured to determine the compensating force based on the force needed by the barrier actuator to keep the barrier member steady. 13. Apparatus according to claim 1, wherein the compensation controller is configured to determine the compensating force based on variations in pressure in the immersion liquid or variations in pressure of liquid or gas in a bearing or seal of the liquid supply system. 14. Apparatus according to claim 13, further comprising a pressure sensor configured to measure the pressure in the immersion liquid, in a seal or in a bearing, a force sensor configured to measure a force between the liquid supply system and the projection system, or both. 15. Apparatus according to claim 1, wherein the actuator is configured to apply force to at least part of the substrate table which supports the substrate. 16. Apparatus according to claim 15, wherein the compensation controller is configured to determine the compensating force based on the desired or actual position of the center of gravity of the part of the substrate table supporting the substrate relative to the projection system. 17. Apparatus according to claim 1, wherein the compensation controller is configured to apply a compensating force on the substrate in a direction substantially parallel to the optical axis of the projection system, and rotationally about axes substantially orthogonal to the optical axis of the projection system. 18. A device manufacturing method comprising: projecting a patterned beam of radiation through an immersion liquid onto a target portion of a substrate using a projection system; and determining and applying a compensating force on the substrate substantially equal in magnitude and opposite in direction to force applied to the substrate by a liquid supply system providing the immersion liquid. 19. The method according to claim 18, wherein the compensation force is determined in a feed-forward manner. 20. The method according to claim 18, wherein the compensation force is determined in a feedback manner. 21. The method according to claim 18, wherein the compensation force is determined based on the actual or a desired position of the substrate. 22. The method according to claim 18, wherein the compensation force is determined based on force applied to the substrate by the liquid supply system due to gravity. 23. The method according to claim 18, wherein the compensating force is determined based on variations in pressure in the immersion liquid. 24. The method according to claim 18, wherein the compensating force is determined based on variations in pressure in a seal, bearing or both. 25. The method according to claim 18, wherein the compensating force is determined based on a force needed by an actuator to keep a barrier member steady, the barrier member at least partly defining a space between the projection system and the substrate which is at least partially filled with the immersion liquid. 26. The method according to claim 18, wherein the compensating force is determined based on a force between the liquid supply system and the projection system. 27. The method according to claim 18, wherein the compensating force is determined based on a desired or actual position of the center of gravity of at least part of a substrate table supporting the substrate relative to the projection system. 28. The method according to claim 18, wherein the compensation force is applied on the substrate in a direction substantially parallel to the optical axis of the projection system, and rotationally about axes substantially orthogonal to the optical axis of the projection system. | FIELD The present invention relates to a lithographic apparatus and a device manufacturing method. BACKGROUND A lithographic apparatus is a machine that applies a desired pattern onto a target portion of a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that circumstance, a patterning device, such as a mask, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. comprising part of, one or several dies) on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate will contain a network of adjacent target portions that are successively exposed. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the projection beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It has been proposed to immerse the substrate in the lithographic projection apparatus in a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the final element of the projection system and the substrate. The point of this is to enable imaging of smaller features since the exposure radiation will have a shorter wavelength in the liquid. (The effect of the liquid may also be regarded as increasing the effective NA of the system and also increasing the depth of focus.) Other immersion liquids have been proposed, including water with solid particles (e.g. quartz) suspended therein. However, submersing the substrate or substrate and substrate table in a bath of liquid (see for example U.S. Pat. No. 4,509,852, hereby incorporated in its entirety by reference) means that there is a large body of liquid that must be accelerated during a scanning exposure. This requires additional or more powerful motors and turbulence in the liquid may lead to undesirable and unpredictable effects. One of the solutions proposed is for a liquid supply system to provide liquid on only a localized area of the substrate and in between the final element of the projection system and the substrate using a liquid supply system (the substrate generally has a larger surface area than the final element of the projection system). One way which has been proposed to arrange for this is disclosed in PCT patent application publication no. WO 99/49504, hereby incorporated in its entirety by reference. As illustrated in FIGS. 2 and 3, liquid is supplied by at least one inlet IN onto the substrate, preferably along the direction of movement of the substrate relative to the final element, and is removed by at least one outlet OUT after having passed under the projection system. That is, as the substrate is scanned beneath the element in a −X direction, liquid is supplied at the +X side of the element and taken up at the −X side. FIG. 2 shows the arrangement schematically in which liquid is supplied via inlet IN and is taken up on the other side of the element by outlet OUT which is connected to a low pressure source. In the illustration of FIG. 2 the liquid is supplied along the direction of movement of the substrate relative to the final element, though this does not need to be the case. Various orientations and numbers of in- and out-lets positioned around the final element are possible, one example is illustrated in FIG. 3 in which four sets of an inlet with an outlet on either side are provided in a regular pattern around the final element. SUMMARY It would be advantageous, for example, to provide improved through-put, improved overlay and/or improved critical dimension performance of an immersion lithography apparatus. According to an aspect, there is provided a lithographic apparatus comprising: an illumination system configured to provide a beam of radiation; a support structure configured to hold a patterning device, the patterning device configured to impart the beam with a pattern in its cross-section; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; a liquid supply system configured to provide an immersion liquid between the projection system and the substrate table; an actuator configured to apply a force to the substrate; and a compensation controller configured to determine a compensating force to be applied by the actuator to the substrate to be substantially equal in magnitude and substantially opposite in direction to a force applied to the substrate by the liquid supply system. Any one or more disturbance forces applied to the substrate that are transmitted by or caused by the liquid supply system may be compensated so as not to affect the position of the substrate. Any source of such disturbance force can be compensated in this way. Examples include force applied to the substrate by the liquid supply system due to gravity, due to variations in pressure in the immersion liquid and due to variations in pressure of liquid and/or gas being removed at a seal or bearing between the barrier member and the substrate or substrate table. Forces from or caused by any one or combination of these sources may be compensated for by the compensation controller. If the liquid supply system comprises a barrier member which is positioned in a direction substantially parallel to the optical axis of the projection system using a barrier actuator, the compensation controller may be configured to determine the required compensation force based on the force needed by the barrier actuator to keep the barrier member steady or by a signal given by a force sensor between the barrier member and the projection system. In an embodiment, the compensation controller is configured to determine the compensation force in a feed-forward manner. For example, the compensation controller may determine the compensation force based on a desired position of the substrate. This may be done from a determination of the force of gravity on the liquid supply system, particularly in the case of a localized area liquid supply system (e.g., having a barrier member) where the components of the liquid supply system may remain stationary in a plane orthogonal to the optical axis of the projection system. In such a case, the position, relative to the center of gravity of the substrate table, at which force from the liquid supply system is transmitted to the substrate, varies with the position of the substrate table. This can lead to rotational torques in the plane orthogonal to the optical axis which, if not, compensated for by the compensation controller, could lead to a reduction in imaging performance of the apparatus, particularly imaging and overlay. There may be other occasions when the liquid supply system exerts a force on the substrate table directly without exerting the same force on the substrate. In such circumstances the compensation controller may be configured to control the actuator to apply compensating force on the substrate table substantially equal in magnitude and opposite in direction to the force applied to the substrate table by the immersion liquid supply system. The apparatus may further comprise a pressure sensor configured to measure the pressure in the immersion liquid and/or gas and/or liquid pressure in a seal or bearing. This is particularly useful if the compensation controller determines the compensating force based on variations in pressure in the immersion liquid (e.g., in the space) or in the seal or bearing. According to a further aspect, there is provided a device manufacturing method comprising: projecting a patterned beam of radiation through an immersion liquid onto a target portion of a substrate using a projection system; and determining and applying a compensating force on the substrate substantially equal in magnitude and opposite in direction to force applied to the substrate by a liquid supply system providing the immersion liquid. Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion”, respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or a metrology or inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers. The terms “radiation” and “beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of 365, 248, 193, 157 or 126 nm). The term “patterning device” used herein should be broadly interpreted as referring to any device that can be used to impart a projection beam with a pattern in its cross-section such as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the projection beam may not exactly correspond to the desired pattern in the target portion of the substrate. Generally, the pattern imparted to the projection beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit. A patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions; in this manner, the reflected beam is patterned. In each example of a patterning device, the support structure may be a frame or table, for example, which may be fixed or movable as required and which may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device”. The term “projection system” used herein should be broadly interpreted as encompassing various types of projection system, including refractive optical systems, reflective optical systems, and catadioptric optical systems, as appropriate for example for the exposure radiation being used, or for other factors such as the use of an immersion fluid or the use of a vacuum. Any use of the term “lens” herein may be considered as synonymous with the more general term “projection system”. The illumination system may also encompass various types of optical components, including refractive, reflective, and catadioptric optical components for directing, shaping, or controlling the projection beam of radiation, and such components may also be referred to below, collectively or singularly, as a “lens”. The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and/or two or more mask tables). In such “multiple stage” machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: FIG. 1 depicts a lithographic apparatus according to an embodiment of the invention; FIG. 2 illustrates, in cross-section, a liquid supply system which may be used with the present invention; FIG. 3 illustrates the liquid supply system of FIG. 2 in plan; FIG. 4 illustrates, in plan and in cross-section, another liquid supply system which may be used in the present invention; FIG. 5 illustrates, in cross-section, a substrate table and liquid supply system according to an embodiment of the present invention; FIG. 6 illustrates the positional dependence of the substrate table on the compensation force needed according to an embodiment of the present invention; and FIG. 7 illustrates two possible ways of establishing the compensation force needed according to an embodiment of the present invention. DETAILED DESCRIPTION FIG. 1 schematically depicts a lithographic apparatus according to a particular embodiment of the invention. The apparatus comprises: an illumination system (illuminator) IL for providing a projection beam PB of radiation (e.g. UV radiation or). a first support structure (e.g. a mask table) MT for supporting a patterning device (e.g. a mask) MA and connected to a first positioning device PM for accurately positioning the patterning device with respect to item PL; a substrate table (e.g. a wafer table) WT for holding a substrate (e.g. a resist-coated wafer) W and connected to a second positioning device PW for accurately positioning the substrate with respect to item PL; and a projection system (e.g. a refractive projection lens) PL for imaging a pattern imparted to the projection beam PB by patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W. As here depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array of a type as referred to above). The illuminator IL receives a beam of radiation from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising for example suitable directing mirrors and/or a beam expander. In other cases the source may be integral part of the apparatus, for example when the source is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system. The illuminator IL may comprise adjusting means AM for adjusting the angular intensity distribution of the beam. Generally, at least the outer and/or inner radial extent (commonly referred to as σ-outer and σ-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL generally comprises various other components, such as an integrator IN and a condenser CO. The illuminator provides a conditioned beam of radiation, referred to as the projection beam PB, having a desired uniformity and intensity distribution in its cross-section. The projection beam PB is incident on the mask MA, which is held on the mask table MT. Having traversed the mask MA, the projection beam PB passes through the lens PL, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioning device PW and position sensor IF (e.g. an interferometric device), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the beam PB. Similarly, the first positioning device PM and another position sensor (which is not explicitly depicted in FIG. 1) can be used to accurately position the mask MA with respect to the path of the beam PB, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the object tables MT and WT will be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the positioning devices PM and PW. However, in the case of a stepper (as opposed to a scanner) the mask table MT may be connected to a short stroke actuator only, or may be fixed. Mask MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The depicted apparatus can be used in the following preferred modes: 1. In step mode, the mask table MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the projection beam is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. 2. In scan mode, the mask table MT and the substrate table WT are scanned synchronously while a pattern imparted to the projection beam is projected onto a target portion C (i.e. a single dynamic exposure). The velocity and direction of the substrate table WT relative to the mask table MT is determined by the (de-) magnification and image reversal characteristics of the projection system PL. In scan mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion. 3. In another mode, the mask table MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the projection beam is projected onto a target portion C. In this mode, generally a pulsed radiation source is employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array of a type as referred to above. Combinations and/or variations on the above described modes of use or entirely different modes of use may also be employed. One or more embodiments of the present invention concern measures which can be taken to reduce the disturbance forces introduced by the supply of liquid between the projection system and the substrate in immersion lithography, e.g., reduction of disturbance forces which may be transmitted to the substrate by a liquid supply system. Embodiments of the present invention are applicable to any type of liquid supply system, in particular localized area liquid supply systems which supply liquid to only a localized area of the substrate (compared with, e.g., a bath in which the substrate and perhaps substrate table are immersed). FIGS. 2 and 3 illustrate a liquid supply system supported in the Z direction by a base frame BF or a metrology reference frame RF (which is supported by but isolated from the base frame). FIG. 4 illustrates a liquid supply system using a barrier member which has an orifice in which a final element of the projection system PL is situated. Thus, the barrier member at least partly surrounds the final element of the projection system PL and forms a space for immersion liquid between the final element of the projection system PL and the substrate W. This type of liquid supply system can either have its weight supported by the projection system PL, by the base frame BF or any other frame or may support its weight through a hydro-static, hydro-dynamic or gas bearing on the substrate W. A further generic type of liquid confinement system comprises a barrier member which at least partly surrounds a bottom portion of the projection system and forms a space, defined by the substrate, the barrier member and the bottom portion of the projection system PL, to which liquid is supplied. Such a liquid supply system is disclosed in, for example, European Patent application nos. 03257070.7 and 03256643.2, both of which are hereby incorporated in their entirety by reference. In an embodiment, the weight of the barrier member is supported on the substrate W and/or the substrate table WT by a gas bearing, e.g., provided on the under side of the barrier member. The barrier member is connected to the base frame BF but only substantially to prevent movement in the XY plane. Alternatively, a similar barrier member may be used in which hydrostatic pressure is used to support the barrier member on the substrate W and/or the substrate table WT. Such a system is disclosed in European Patent application no. 03254078.3, hereby incorporated in its entirety by reference. A further variation of the barrier member is disclosed in U.S. patent application Ser. No. 10/743,271, filed 23 Dec. 2003, hereby incorporated in its entirety by reference. The materials of which the above mentioned liquid supply systems are constructed, and in particular barrier members, are chosen so that they have no adverse effects on contact with the immersion liquid (e.g. corrosion), they do not deteriorate the quality of the immersion liquid e.g. by dissolving in the immersion liquid, and they are compatible with all other requirements related to lithography that are not specific to immersion. Typical examples include austenitic stainless steels (e.g. the AISI 300 series and equivalents), nickel and nickel-based alloys, cobalt and cobalt-based alloys, chromium and chromium-based alloys, titanium and titanium-based alloys. However, in order to prevent galvanic corrosion, it is best to avoid combinations of several different metals in the design. Polymers may also be used and suitable polymers include many fluorine-based polymers (e.g. PTFE (Teflon™), PFA and PVDF) also, uncolored PE and PP could be used as well as all ceramic materials, with the exception of aluminum nitride. Ceramic-based composite materials may also be suitable as may be glasses (e.g. fused silica or quartz glass) and low thermal expansion glasses or glass ceramics (e.g. ULE™) from Corning or Zerodur™) from Schott). Disturbance forces which might be transmitted to the substrate W include forces due to gravity (for those liquid supply systems which are at least in part supported by the substrate) and the effect of immersion liquid pressure on the substrate W (for all types of liquid supply system). Other disturbance forces are, for example, from liquid or gas bearings or seals operating between the liquid supply system and substrate W and/or substrate table WT (e.g., gas bearings or gas seals on the underside of a barrier member) or due to activated movements in the Z, Rz, Rx and Ry directions of the liquid supply system. In some circumstances, the bearing or seal removes liquid and/or gas from the liquid supply system. The pressure of the liquid and/or gas can vary and cause disturbance forces to be transmitted to the substrate table WT. An embodiment of the substrate table WT assembly is illustrated in FIG. 5. What is illustrated in FIG. 5 is an example only and the substrate table WT may have a different construction. The principles explained in relation to FIG. 5 (and FIGS. 6 and 7) are equally applicable to other types of substrate table WT as well as, of course, other types of liquid supply system. In FIG. 5, a liquid supply system with a barrier member 10 is illustrated. A gas seal 15 seals between the bottom of the barrier member 10 and the substrate W and/or substrate table WT. The barrier member 10 provides a space 5 which can be filled with immersion liquid so that the space between the projection system PL, the substrate W and bounded by the barrier member 10 is filled with immersion liquid. The apparatus includes a compensation controller for controlling one or more actuators 45 to apply a compensating force on the substrate W substantially equal in magnitude and opposite in direction to force applied to the substrate by the liquid supply system. The substrate table WT is comprised of two main parts 40, 60. The upper main part 40 is designed for accurate fine positioning of the substrate W, which is carried by the upper main part 40. The lower main part 60 is moved by actuator(s) 65 on a coarse scale, final accurate positioning being achieved by movement of the upper main part 40 by actuator(s) 45 which act between the upper and lower main parts 40, 60. One or more embodiments are described below referring to one or more actuators 45 between the upper and lower main parts of the substrate table 40, 60 but of course is equally applicable to other substrate tables such as those types that only have one part or indeed those types that have more than two parts. While described in relation to one or more actuators 45 being the main fine three dimensional positioning actuators, separate actuators may be specifically provided for applying the compensating forces required. These compensating forces may even be applied directly to the substrate W or could indeed be applied by the actuator(s) 65 for the main lower part of the substrate table WT. Both actuators 45, 65 are capable of moving their respective parts of the substrate table 40, 60 in the XY plane and, to a more limited extent, in the Z direction relative to the lower main part 60 and to the base frame BF respectively. FIG. 6 illustrates how an embodiment of the present invention uses the compensation controller 30 to determine the necessary compensation force and to control the actuator(s) 45 to compensate for the effect of gravity of the barrier member 10 on the substrate W in the case where the barrier member 10 is supported by the substrate W (for example through a hydrostatic, hydrodynamic or gas bearing). The determinations preferably account for Rx, Ry and Rz rotational movements as well as Z movements. The same principles can be applied when considering the effects of disturbance forces transmitted through the immersion liquid and which will be described in more detail in relation to FIG. 7. In both cases, the forces applied to the substrate table W may be estimated as being through the center of gravity of the barrier member 10 or the center of the area of the substrate WT covered by immersion liquid from the liquid supply system. The determinations by the compensation controller 30 may be made, for example, by calculation, table look-up or any other means. The compensation controller 30 may be, for example, mechanical, electronic and/or software based. FIG. 6 illustrates a 3-dimensional problem in two dimensions. Although the weight of the barrier member 10 is constant, as can be seen from FIG. 6, when the center of the substrate W moves away from directly underneath the optical axis of the projection system (indicated as dotted line 1) a moment 100 around the center of gravity of the upper part of the substrate table 40 is generated. In the case illustrated in FIG. 6 this requires a larger compensating force F1 to be applied on the left hand actuator 45 than the compensating force F2 applied to the right hand actuator 45. The actuators 45 must apply a force to support both the upper part 40 of the substrate table and the barrier member. If the substrate table WT were moved to the right, the force on the left hand actuator F1 would increase and the force on the right hand actuator F2 would need to reduce. Thus, it can be seen that the compensation controller can determine the compensating force based on a desired position of the substrate W and control the actuator 45 accordingly. The determination can also be carried out using the actual X, Y position as this is usually only a few nm different to the desired position. The actuators 45 are controlled to apply compensating force on the substrate table substantially equal in magnitude and opposite in direction to the force applied to the substrate by the liquid supply system. It is also possible that the liquid supply system applies forces to the substrate table WT directly and not through the substrate. In this case the same principles apply and the compensation controller can compensate for any disturbances caused in this way. The compensation controller 30 can determine the compensation force in a feed-forward manner by being fed the desired (or actual) co-ordinates of the substrate W. From this information the combined center of gravity of the upper part of the substrate table 40 and of the barrier member 10 can be determined from a knowledge of their positions and masses and the force applied to actuator 45 as appropriate. Clearly the determinations can be based on any point in space. The determinations can be carried out from a knowledge of the mass of the barrier member 10 and its position as well as the mass of the upper part 40 of the substrate table, including the substrate W. Referring to FIG. 7, the compensation controller 30 can additionally or alternatively determine a compensation force required due to pressure of the liquid and/or gas in a seal or bearing or pressure of liquid in the space. The pressures can be measured and the determination performed in a feed forward or feed back manner. For this purpose a pressure sensor 80 is provided or data from a force sensor 70 can be used. Alternatively, the pressure can be determined from, for example, a knowledge of the flow rate of liquid into and/or out of the space 5. In this way the inherent variations in pressure of the immersion liquid in the space 5 due to extraction of gas/liquid mixture can be compensated. In an embodiment, a compensation force component is added to the overall force signal generated for each of the actuators 45. The other components include that for positioning of the substrate W as well as that for compensating the force of gravity on the upper part 40. It will be appreciated that similar compensation forces to those generated by upper actuators 45 may need to be generated by lower actuators 65 in that the forces on the lower part 60 are balanced. If the barrier member 10 is partly supported by another part of the apparatus other than the substrate W or substrate table WT, and is actuated in the Z direction by an actuator 70, it is possible to measure the force on the substrate W or substrate table WT from a knowledge of the force applied by the actuator 70. The actuator 70 may be a electromagnetic motor, a piezoelectric motor, a gas, hydrodynamic or hydrostatic bearing between the barrier member 10 and the substrate W and/or substrate table WT, or any other sort of actuator. Information about the forces applied by the actuators can be used to determine the force on the substrate W and used (in a feed-forward manner) to determine the compensation force required. Alternatively or additionally, the element 70 may be a force sensor 70 which outputs a signal representing the force between the barrier member and the projection system which can be used by the compensation controller to determine the required compensation force. The compensation force may be filtered (and thereby corrected) for certain dynamic properties of the liquid supply system, for example dynamic properties of the barrier member 10 (such as bending for example) and possible seal/bearing characteristics (such as elasticity). The compensation controller may also determine the compensation force in a feedback manner based on any variable other than the position of the table. For example the feedback determination may be on the basis of the force sensor 70 output or the actuator force or the pressure of the liquid in the space and/or pressure of liquid and/or gas at the seal and/or bearing. As stated above, the pressure of liquid in space 5, seal and/or bearing can apply a force (pressure times area) to the substrate W or substrate table WT. The moment applied to the upper part of the substrate table 40 by the immersion liquid is also positionally dependent and the force can be determined from a knowledge of the pressure of immersion liquid in the space 5 and the surface area over which that pressure is applied. Another immersion lithography solution which has been proposed is to provide the liquid supply system with a seal member which extends along at least a part of a boundary of the space between the final element of the projection system and the substrate table. The seal member is substantially stationary relative to the projection system in the XY plane though there may be some relative movement in the Z direction (in the direction of the optical axis). A seal is formed between the seal member and the surface of the substrate. Preferably the seal is a contactless seal such as a gas seal. Such a system is disclosed in, for example, U.S. patent application Ser. No. 10/705,783, hereby incorporated in its entirety by reference. A further immersion lithography solution with a localized liquid supply system is shown in FIG. 4. Liquid is supplied by two groove inlets IN on either side of the projection system PL and is removed by a plurality of discrete outlets OUT arranged radially outwardly of the inlets IN. The inlets IN and OUT can be arranged in a plate with a hole in its center and through which the projection beam is projected. Liquid is supplied by one groove inlet IN on one side of the projection system PL and removed by a plurality of discrete outlets OUT on the other side of the projection system PL, causing a flow of a thin film of liquid between the projection system PL and the substrate W. The choice of which combination of inlet IN and outlets OUT to use can depend on the direction of movement of the substrate W (the other combination of inlet IN and outlets OUT being inactive). In European patent application no. 03257072.3, hereby incorporated in its entirety by reference, the idea of a twin or dual stage immersion lithography apparatus is disclosed. Such an apparatus is provided with two substrate tables for supporting the substrate. Leveling measurements are carried out with a substrate table at a first position, without immersion liquid, and exposure is carried out with a substrate table at a second position, where immersion liquid is present. Alternatively, the apparatus can have only one substrate table moving between the first and second positions. The present invention can be applied to any immersion lithography apparatus, in particular, but not exclusively, to those types mentioned above. While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The description is not intended to limit the invention. | <SOH> BACKGROUND <EOH>A lithographic apparatus is a machine that applies a desired pattern onto a target portion of a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that circumstance, a patterning device, such as a mask, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. comprising part of, one or several dies) on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate will contain a network of adjacent target portions that are successively exposed. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the projection beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It has been proposed to immerse the substrate in the lithographic projection apparatus in a liquid having a relatively high refractive index, e.g. water, so as to fill a space between the final element of the projection system and the substrate. The point of this is to enable imaging of smaller features since the exposure radiation will have a shorter wavelength in the liquid. (The effect of the liquid may also be regarded as increasing the effective NA of the system and also increasing the depth of focus.) Other immersion liquids have been proposed, including water with solid particles (e.g. quartz) suspended therein. However, submersing the substrate or substrate and substrate table in a bath of liquid (see for example U.S. Pat. No. 4,509,852, hereby incorporated in its entirety by reference) means that there is a large body of liquid that must be accelerated during a scanning exposure. This requires additional or more powerful motors and turbulence in the liquid may lead to undesirable and unpredictable effects. One of the solutions proposed is for a liquid supply system to provide liquid on only a localized area of the substrate and in between the final element of the projection system and the substrate using a liquid supply system (the substrate generally has a larger surface area than the final element of the projection system). One way which has been proposed to arrange for this is disclosed in PCT patent application publication no. WO 99/49504, hereby incorporated in its entirety by reference. As illustrated in FIGS. 2 and 3 , liquid is supplied by at least one inlet IN onto the substrate, preferably along the direction of movement of the substrate relative to the final element, and is removed by at least one outlet OUT after having passed under the projection system. That is, as the substrate is scanned beneath the element in a −X direction, liquid is supplied at the +X side of the element and taken up at the −X side. FIG. 2 shows the arrangement schematically in which liquid is supplied via inlet IN and is taken up on the other side of the element by outlet OUT which is connected to a low pressure source. In the illustration of FIG. 2 the liquid is supplied along the direction of movement of the substrate relative to the final element, though this does not need to be the case. Various orientations and numbers of in- and out-lets positioned around the final element are possible, one example is illustrated in FIG. 3 in which four sets of an inlet with an outlet on either side are provided in a regular pattern around the final element. | <SOH> SUMMARY <EOH>It would be advantageous, for example, to provide improved through-put, improved overlay and/or improved critical dimension performance of an immersion lithography apparatus. According to an aspect, there is provided a lithographic apparatus comprising: an illumination system configured to provide a beam of radiation; a support structure configured to hold a patterning device, the patterning device configured to impart the beam with a pattern in its cross-section; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; a liquid supply system configured to provide an immersion liquid between the projection system and the substrate table; an actuator configured to apply a force to the substrate; and a compensation controller configured to determine a compensating force to be applied by the actuator to the substrate to be substantially equal in magnitude and substantially opposite in direction to a force applied to the substrate by the liquid supply system. Any one or more disturbance forces applied to the substrate that are transmitted by or caused by the liquid supply system may be compensated so as not to affect the position of the substrate. Any source of such disturbance force can be compensated in this way. Examples include force applied to the substrate by the liquid supply system due to gravity, due to variations in pressure in the immersion liquid and due to variations in pressure of liquid and/or gas being removed at a seal or bearing between the barrier member and the substrate or substrate table. Forces from or caused by any one or combination of these sources may be compensated for by the compensation controller. If the liquid supply system comprises a barrier member which is positioned in a direction substantially parallel to the optical axis of the projection system using a barrier actuator, the compensation controller may be configured to determine the required compensation force based on the force needed by the barrier actuator to keep the barrier member steady or by a signal given by a force sensor between the barrier member and the projection system. In an embodiment, the compensation controller is configured to determine the compensation force in a feed-forward manner. For example, the compensation controller may determine the compensation force based on a desired position of the substrate. This may be done from a determination of the force of gravity on the liquid supply system, particularly in the case of a localized area liquid supply system (e.g., having a barrier member) where the components of the liquid supply system may remain stationary in a plane orthogonal to the optical axis of the projection system. In such a case, the position, relative to the center of gravity of the substrate table, at which force from the liquid supply system is transmitted to the substrate, varies with the position of the substrate table. This can lead to rotational torques in the plane orthogonal to the optical axis which, if not, compensated for by the compensation controller, could lead to a reduction in imaging performance of the apparatus, particularly imaging and overlay. There may be other occasions when the liquid supply system exerts a force on the substrate table directly without exerting the same force on the substrate. In such circumstances the compensation controller may be configured to control the actuator to apply compensating force on the substrate table substantially equal in magnitude and opposite in direction to the force applied to the substrate table by the immersion liquid supply system. The apparatus may further comprise a pressure sensor configured to measure the pressure in the immersion liquid and/or gas and/or liquid pressure in a seal or bearing. This is particularly useful if the compensation controller determines the compensating force based on variations in pressure in the immersion liquid (e.g., in the space) or in the seal or bearing. According to a further aspect, there is provided a device manufacturing method comprising: projecting a patterned beam of radiation through an immersion liquid onto a target portion of a substrate using a projection system; and determining and applying a compensating force on the substrate substantially equal in magnitude and opposite in direction to force applied to the substrate by a liquid supply system providing the immersion liquid. Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion”, respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or a metrology or inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers. The terms “radiation” and “beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g. having a wavelength of 365, 248, 193, 157 or 126 nm). The term “patterning device” used herein should be broadly interpreted as referring to any device that can be used to impart a projection beam with a pattern in its cross-section such as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the projection beam may not exactly correspond to the desired pattern in the target portion of the substrate. Generally, the pattern imparted to the projection beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit. A patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions; in this manner, the reflected beam is patterned. In each example of a patterning device, the support structure may be a frame or table, for example, which may be fixed or movable as required and which may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device”. The term “projection system” used herein should be broadly interpreted as encompassing various types of projection system, including refractive optical systems, reflective optical systems, and catadioptric optical systems, as appropriate for example for the exposure radiation being used, or for other factors such as the use of an immersion fluid or the use of a vacuum. Any use of the term “lens” herein may be considered as synonymous with the more general term “projection system”. The illumination system may also encompass various types of optical components, including refractive, reflective, and catadioptric optical components for directing, shaping, or controlling the projection beam of radiation, and such components may also be referred to below, collectively or singularly, as a “lens”. The lithographic apparatus may be of a type having two (dual stage) or more substrate tables (and/or two or more mask tables). In such “multiple stage” machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure. | 20040402 | 20071113 | 20051006 | 84346.0 | 1 | NGUYEN, HUNG | LITHOGRAPHIC APPARATUS AND DEVICE MANUFACTURING METHOD | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,216 | ACCEPTED | Optical arrangement for assay reading device | Disclosed, in one aspect, is an assay result reading device for reading the result of an assay performed using a test strip, the device comprising: a light source or sources, said light source/s emitting light incident upon at least two, spatially separated zones of the test strip; and a photodetector which detects light emanating from each of the two said zones; in a further aspect is disclosed an assay result reading device for reading the result of an assay performed using a test strip, the device comprising: at least one light source incident upon a zone of the test strip; and at least two photodetectors both of which are able to detect some of the light emanating from the zone of the test strip illuminated by the light source. | 1. An assay result reading device for reading the result of an assay performed using a test strip, the device comprising: at least one light source capable of emitting light incident upon at least two spatially separated zones of the test strip; and a photodetector which detects light emanating from each of the two said zones. 2. A reading device according to claim 1, further comprising a second photodetector, wherein both photodetectors are so positioned as to detect at least a portion of the light emanating from at least one of the zones of the test strip. 3. A reading device according to claim 2, wherein the two photodetectors are positioned on opposite sizes of the at least one zone and laterally offset from the at least one zone. 4. A reading device according to claim 1, wherein the at least one light source comprises three light sources. 5. A reading device according to claim 1, wherein the at least one light source comprises a light emitting diode (LED). 6. A reading device according to claim 1, wherein the photodetector comprises a photodiode. 7. A reading device according to claim 1, wherein the photodetector is positioned between the spatially separated zones and laterally offset from the zones. 8. A reading device according to claim 1, further comprising a second photodetector and wherein: the test strip has three spatially separated zones; the at least one light source comprises three LED's; each LED is aligned with and laterally offset from a corresponding test strip zone; a first baffle is so sized and positioned as to prevent light emitted by the first LED from illuminating the third zone; a second baffle is so sized and positioned as to prevent light emitted by the third LED from illuminating the first zone; the first photodetector is so positioned as to receive light emanating from the first zone and the second zone; and the second photodetector is so positioned as to receive light emanating from the second zone and the third zone. 9. A reading device according to claim 1, further comprising a housing enclosing the at least one light source and the photodetector. 10. A reading device according to claim 9, wherein the housing is no larger than about 12 cm long, about 2.5 cm wide, and about 2.2 cm tall. 11. A reading device according to claim 1, wherein the at least one light source and the photodetector are disposed within an area no larger than about 1 square centimeter. 12. A reading device according to claim 1, wherein the at least one light source and the photodetector are disposed within an area no larger than about 0.7 square centimeter. 13. A reading device according to claim 1, further comprising: a computation circuit responsive to signals generated by the photodetector representing the presence or absence of a fluid sample in at least one of the zones to: calculate a flow rate for a fluid flowing along the test strip; compare the calculated flow rate to upper and lower limits; and reject the assay result if the calculated flow rate is outside the upper and lower limits. 14. A reading device according to claim 1, further comprising: a computation circuit, responsive to an input signal representing the amount of an analyte or the rate of accumulation of an analyte in at least one of the zones of the test strip, to: compare the input signal to a first threshold; compare the input signal to a second threshold, the second threshold being less than the first threshold; generate an output signal if the input signal exceeds the first threshold or the input signal is less than the second threshold, the output signal indicative of a first result if the input signal exceeds the first threshold, or, alternatively, the output signal indicative of a second result if the input signal is less than the second threshold; and terminate the assay if the input signal exceeds the first threshold or the signal is less than the second threshold. 15. A reading device according to claim 14, further comprising: a computation circuit responsive to signals generated by the photodetector representing the presence or absence of a fluid sample in at least one of the zones to: calculate a flow rate for a fluid flowing along the test strip; compare the calculated flow rate to upper and lower limits; and reject the assay result if the calculated flow rate is outside the upper and lower limits. 16. An assay result reading device for reading the result of an assay performed using a test strip, the device comprising: at least one light source capable of emitting light incident upon at least one zone of the test strip; and at least two photodetectors, each of which detects light emanating from the at least one zone of the test strip. 17. A method of determining the result of an assay performed using a test strip, the method comprising: positioning the test strip in relation to an assay result reader, the reader comprising a housing enclosing at least one light source and a photodetector; and measuring a light level received by the photodetector; wherein the test strip is so positioned that the at least one light source emits light incident on at least two spatially separated zones of the test strip, and so that light emanating from at least one of the zones is incident on the photodetector. 18. A method according to claim 17, wherein the test strip is positioned at least party inside the assay result reader. 19. A method according to claim 17, wherein the assay result reader further comprises a second photodetector, the at least one light source comprises first, second, and third light sources, the test strip has three spatially separated zones, and wherein: each light source is aligned with and laterally offset from a corresponding test strip zone; the first photodetector is so positioned as to receive light emanating from the first zone and the second zone; and the second photodetector is so positioned as to receive light emanating from the second zone and the third zone. 20. A method of determining the result of an assay performed using a test strip, the method comprising: positioning the test strip in relation to an assay result reader, the reader comprising a housing enclosing at least one light source and at least two photodetectors; and measuring a light level received by the photodetector; wherein the test strip is so positioned that the at least one light source emits light incident on the at least one zone of the test strip, and so that light emanating from the at least one zone is incident on each photodetector. | CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/508,001, filed Oct. 2, 2003, the entire contents of which are hereby incorporated herein by this reference. FIELD The disclosed subject matter relates to assay reading devices for the measurement of analytes. In particular it relates to electronic readers for use with assay test-strips which use optical methods of measurement. INTRODUCTION Disposable analytical devices suitable for home testing of analytes are now widely commercially available. A lateral flow immunoassay device suitable for this purpose for the measurement of the pregnancy hormone human chorionic gonadotropin (hCG) is sold by Unipath under the brand-name CLEARBLUE® and is disclosed in EP291194. EP291194 discloses an immunoassay device comprising a porous carrier containing a particulate labelled specific binding reagent for an analyte, which reagent is freely mobile when in the moist state, and an unlabelled specific binding reagent for the same analyte, which reagent is immobilised in a detection zone or test zone downstream from the unlabelled specific binding reagent. Liquid sample suspected of containing analyte is applied to the porous carrier whereupon it interacts with the particulate labelled binding reagent to form an analyte-binding partner complex. The particulate label is coloured and is typically gold or a dyed polymer, for example latex or polyurethane. The complex thereafter migrates into a detection zone whereupon it forms a further complex with the immobilised unlabelled specific binding reagent enabling the extent of analyte present to be observed. However such commercially available devices as disclosed above require the result to be interpreted by the user. This introduces a degree of subjectivity, which is undesirable. Electronic readers for use in combination with assay test-strips for determining the concentration and/or amount of analyte in a fluid sample are known. EP653625 discloses such a device which uses an optical method in order to determine the result. An assay test strip such as that disclosed in EP291194 is inserted into a reader such that the strip is aligned with optics present within the reader. Light from a light source, such as a light emitting diode (LED), is shone onto the test strip and either reflected or transmitted light is detected by a photodetector. Typically, the reader will have more than one LED, and a corresponding photodetector is provided for each of the plurality of LED's. U.S. Pat. No. 5,580,794 discloses a fully disposable integrated assay reader and lateral flow assay test strip whereby optics present in the reader enable the result to be determined optically using reflectance measurements. An important consideration in assay reading devices of this type is the requirement that the assay reader and the test strip are carefully aligned. This is because the visible signal formed in the detection zone (and the control zone, if present) is fairly narrow (about 1 mm wide), so a small displacement of the detection or control zone relative to the respective photodetector may significantly affect the reading made by the photodetector. In addition, it is generally important that the photodetector is as close as possible to the test strip, because the amount of light which is ‘captured’ by the photodiode is fairly small, and the signal intensity normally obeys the inverse square law, so that it diminishes rapidly as the separation between the test strip and the photodetector increases. Thus there is a requirement for the user to carefully align the test stick with the assay result reader which, especially for devices intended to be used in the home, can be problematic. One solution to this problem is provided by U.S. Pat. No. 5,580,794, wherein the assay strip is provided as an integral component of the result reader, thereby avoiding the need for the user to insert the test strip into the reader. An alternative solution is taught by EP 0833145, which discloses a test strip and assay result reader combination, wherein the assay result reading device can be successfully triggered to make a reading only when there is a precise three-dimensional fit between the test strip and the reader, thereby ensuring the correct alignment has been obtained. SUMMARY The present disclosure provides inexpensive, typically disposable, assay readers either for use with, or in integral combination with, an assay test strip such as disclosed by EP291194. The optics are provided in a compact arrangement well-suited, for example, for a handheld device. The arrangement also provides an optimal or near optimal path length between the light source and photodetector thus establishing a strong signal. In some embodiments, an assay result reading device for reading the result of an assay performed using a test strip includes a light source capable of emitting light incident upon at least two spatially separated zones of the test strip, and a photodetector which detects light emanating from each of the two said zones. A photodetector which is used to detect light emanating from two distinct zones of the test strip, may be referred to as a “shared” photodetector. In some embodiments, an assay result reading device for reading the result of an assay performed using a test strip includes a light source capable of emitting light incident upon a zone of the test strip, and two photodetectors both of which are able to detect some of the light emanating from the zone of the test strip illuminated by the light source. Such a zone, “read” by two or more photodetectors, may be referred to as a “commonly read” zone. In other embodiments, the invention provides methods of reading the result of an assay performed using a test strip in accordance with the embodiments described above. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of an assay result reader; FIG. 2 is a block diagram illustrating schematically some of the internal components of the reading device embodiment depicted in FIG. 1; FIG. 3 is a plan view of certain internal components showing an embodiment of one arrangement; FIG. 4 is a plan view showing an arrangement of certain internal components; FIG. 5 is an elevation view of certain internal components showing an embodiment of one arrangement and exemplary optical paths; FIG. 6 is an exploded top perspective view of a baffle element and a circuit board of an exemplary embodiment; FIG. 7 is a top plan view showing an exemplary baffle arrangement; FIG. 8 is a bottom perspective view showing an exemplary baffle arrangement; FIG. 9 is a bottom plan view showing an exemplary baffle arrangement; FIG. 10 is an exploded cross-sectional side view taken at line 10-10 in FIG. 7 showing an exemplary baffle arrangement, circuit board, and a test strip; and FIG. 11 is a transverse cross-sectional view taken at line 11-11 in FIG. 10 showing an exemplary baffle arrangement and a test strip. DETAILED DESCRIPTION The optical arrangements for assay readers described herein promote simplicity and economy. The manufacturing cost of the device is an especially important consideration if the reader is intended to be disposable; the photodetectors themselves, being relatively expensive components, form a significant part of the overall cost. A further advantage is that the arrangement can provide greater accuracy and reduce the need for accurate positioning of the test strip relative to the reader. Suppose, for example, a test strip were provided with two separate, but closely spaced, control zones and a photodetector were positioned in the reader so as to be between the two control zones. If the test strip were slightly misaligned, laterally, relative to the assay reader device, the signal from one of the control zones would be less intense as the zone in question would be further from the photodetector. However, the other control zone would necessarily be closer to the photodetector by a corresponding amount, and would therefore provide a stronger signal to compensate for the weaker signal from the other zone. Furthermore it has been observed that the amount of bound material present at a particular zone will vary along the length of the zone in the direction of liquid flow. Preferential binding of the analyte takes place at the leading boundary edge and diminishes along the length of the zone in the direction of liquid flow. Thus any misalignment may result in a greater error than might have been expected if the analyte were captured in a uniform fashion. U.S. Pat. No. 5,968,839 discloses an electronic assay reader for use with a test strip, wherein it is attempted to compensate for this non-uniform binding by the provision in the relevant binding zone of a plurality of deposits of immobilised capture reagent, the density of which deposits increases from the leading boundary to the trailing edge of the zone. Similarly, some of the arrangements described herein also reduce the requirement for precise relative positioning of the test strip and the assay result reading device: there is an in-built signal compensation for any misalignment between the test strip and the assay result reader for any zone which is commonly read by the two or more photodetectors, because relative movement of the commonly read zone away from one of the photodetectors will necessarily (within certain limits) involve movement by a corresponding amount towards the other photodetector/s. The light emanating from the zone or zones, as appropriate, may be light which is reflected from the test strip or, in the case of a test strip which is transparent or translucent (especially when wet e.g. following the application of a liquid sample), light which is transmitted through the test strip. For the purposes of the present specification, light incident upon a particular zone of a test strip from a light source, and reflected by the strip or transmitted therethrough, may be regarded as “emanating” from the strip, although of course the light actually originates from the light source. The preferred light sources are light emitting diodes (LED's), and the preferred photodetector is a photodiode. Reflected light and/or transmitted light may be measured by the photodetector. For the present purposes, reflected light is taken to mean that light from the light source is reflected from the test strip onto the photodetector. In this situation, the detector is typically provided on the same side of the test strip as the light source. Transmitted light refers to light that passes through the test strip and typically the detector is provided on the opposite side of the test strip to the light source. For the purposes of a reflectance measurement, the test strip may be provided with a backing such as a white reflective MYLAR® plastic layer. Thus light from the light source will fall upon the test strip, some will be reflected from its surface and some will penetrate into the test strip and be reflected at any depth up to and including the depth at which the reflective layer is provided. Thus, a reflectance type of measurement may actually involve transmission of light through at least some of the thickness of the test strip. Generally, measurement of reflected light is preferred. It is especially preferred that the reading device of the second aspect comprises a plurality of light sources, each light source being incident upon a respective zone of the test strip. In principle, an assay result reading device in accordance with the present disclosure may comprise any number of light sources and any number of photodetectors. For example, one embodiment includes three light sources, each illuminating a respective zone of a test strip, and a single photodetector which is shared by all three zones. In practice it is difficult to arrange for more than three zones to share a single photodetector, because the photodetector will have trouble in detecting a sufficiently strong signal from those zones which are furthest away. In preferred embodiments, an assay result reader feature both “shared” photodetectors as well as “commonly read” zones; i.e., a single photodetector can receive light emanating from more than one zone, and light emanating from a single zone is received by more than one photodetector. In this instance, the reader will typically include a plurality of light sources and a smaller plurality of photodetectors. In particular, where the reader comprises x light sources for illuminating the test strip, it will comprise x−1 photodetectors. The number of detectors required might be reduced still further by sharing of the photodetectors between the respective light sources, e.g. using three photodetectors to detect light emanating from an assay test strip that has been illuminated by five light sources. More specifically, a preferred embodiment of an assay result readers includes first, second and third light sources, each light source illuminating respective first, second or third zones of a test strip. Conveniently the first light source illuminates a test zone or detection zone; the second light source illuminates a reference zone; and the third light source illuminates a control zone. The test or detection zone is a zone of the test strip in which an optical signal is formed (e.g. accumulation or deposition of a label, such as a particulate coloured binding reagent) in the presence or absence, as appropriate, of the analyte of interest. (By way of explanation some assay formats, such as displacement assays, may lead to the formation of signal in the absence of the analyte of interest). The control zone is a zone of the test strip in which an optical signal is formed irrespective of the presence or absence of the analyte of interest to show that the test has been correctly performed and/or that the binding reagents are functional. The reference zone is a zone wherein, typically, only “background” signal is formed which can be used, for example, to calibrate the assay result reading device and/or to provide a background signal against which the test signal may be referenced. In this particular preferred embodiment, the reader also includes two photodetectors. The first photodetector is substantially adjacent to or primarily associated with the first light source and is intended to detect light emanating the zone of the test strip illuminated by the respective light source. However, the photodetector is so positioned as to be also capable of detecting some of the light emanating from the second zone of the test strip, illuminated by the second light source. The second photodetector is substantially adjacent to or primarily associated with the third light source and is intended to detect light emanating from the zone of the test strip illuminated by the respective light source. However the photodetector is so positioned as to be also capable of detecting some of the light emanating from the second zone of the test strip, illuminated by the second light source. Accordingly, this embodiment features a “shared” photodetector, because it includes a plurality of light sources and a photodetector which detects light emanating from at least two spatially separated zones of the test strip. In addition, this embodiment has “commonly read” zones, because it comprises two photodetectors, both of which are able to detect some of the light emanating from a zone of the test strip (in this instance, two photodetectors are able to detect light emanating from the second zone of the test strip). It is preferred that, when the assay strip is correctly inserted into a reader device, a commonly read zone will be at a position intermediate between the two photodetectors, such that (within certain limits) a lateral movement away from one of the photodetectors will inevitably involve a corresponding lateral movement towards the other photodetectors, so as to allow for the desired signal compensation effect. Typically, but not essentially, the commonly read zone will be approximately equidistant from the two photodetectors when the test strip is correctly positioned within the reader. It is also preferred that, where an assay result reading device includes a plurality of light sources, these are advantageously arranged such that a particular zone is illuminated only by a single one of the plurality of light sources. For example, optical baffles may be provided between or around the light sources so as to limit the portion of the test strip illuminated by each light source. For the avoidance of doubt, it is expressly stated that any features described as “preferred”, “desirable”, “convenient”, “advantageous” or the like may be adopted in an embodiment of an assay result reader in combination with any other feature or features so-described, or may be adopted in isolation, unless the context dictates otherwise. EXAMPLES A number of Examples are provided to illustrate selected aspects and embodiments of the disclosed subject matter. These Examples merely provide instantiations of systems, devices, and/or methods and are not intended to limit the scope of the disclosure. Example 1 An embodiment of an assay result reading device having both “shared” photodetectors and “commonly read” zones is illustrated in FIG. 1. The reading device is about 12 cm long and about 2 cm wide and is generally finger or cigar-shaped. In preferred embodiments, the housing is no larger than about 12 cm long, about 2.5 cm wide, and about 2.2 cm tall. However, any convenient shape may be employed, such as a credit card shaped reader. The device comprises a housing 2 formed from a light-impermeable synthetic plastics material (e.g. polycarbonate, ABS, polystyrene, high density polyethylene, or polypropylene or polystyrol containing an appropriate light-blocking pigment, such as carbon). At one end of the reading device is a narrow slot or aperture 4 by which a test strip (not shown) can be inserted into the reader. On its upper face the reader has two oval-shaped apertures. One aperture accommodates the screen of a liquid crystal display 6 which displays information to a user e.g. the results of an assay, in qualitative or quantitative terms. The other aperture accommodates an eject mechanism actuator 8 (in the form of a depressible button), which when actuated, forcibly ejects an inserted assay device from the assay reading device. The test strip for use with the reading device is a generally conventional lateral flow test stick e.g. of the sort disclosed in U.S. Pat. No. 6,156,271, U.S. Pat. No. 5,504,013, EP 728309, or EP 782707. The test strip and a surface or surfaces of the slot in the reader, into which the test strip is inserted, are so shaped and dimensioned that the test strip can only be successfully inserted into the reader in the appropriate orientation. When a test strip is correctly inserted into the reader, a switch is closed which activates the reader from a “dormant” mode, which is the normal state adopted by the reader, thereby reducing energy consumption. Enclosed within the housing of the reader (and therefore not visible in FIG. 1) are a number of further components, illustrated schematically in FIG. 2. Referring to FIG. 2, the reader comprises three LED's 10a, b, and c. When a test strip is inserted into the reader, each LED 10 is aligned with a respective zone of the test strip. LED 10a is aligned with the test zone, LED 10b is aligned with the reference zone and LED 10c is aligned with the control zone. Two photodiodes 12 detect light reflected from the various zones and generate a current, the magnitude of which is proportional to the amount of light incident upon the photodiodes 12. The current is converted into a voltage, buffered by buffer 14 and fed into an analogue to digital converter (ADC, 16). The resulting digital signal is read by microcontroller 18. One photodiode detects light reflected from the test zone and some of the light reflected from the reference zone. The other photodiode 12 detects some of the light reflected from the reference zone and the light reflected from the control zone. The microcontroller 18 switches on the LED's 10 one at a time, so that only one of the three zones is illuminated at any given time—in this way the signals generated by light reflected from the respective zones can be discriminated on a temporal basis. FIG. 2 further shows, schematically, the switch 20 which is closed by insertion of an assay device into the reader, and which activates the microcontroller 18. Although not shown in FIG. 2, the device further comprises a power source (typically a button cell), and an LCD device responsive to output from the microcontroller 18. In use, a dry test strip (i.e. prior to contacting the sample) is inserted into the reader, this closes the switch 20 activating the reader device, which then performs an initial calibration. The intensity of light output from different LED's 10 is rarely identical. Similarly, the photodetectors 12 are unlikely to have identical sensitivities. Because such variation could affect the assay reading an initial calibration is effected, in which the microcontroller adjusts the length of time that each of the three LED's is illuminated, so that the measured signal from each of the three zones (test, reference and control) is approximately equal and at a suitable operating position in a linear region of the response profile of the system (such that a change in intensity of light reflected from the various zones produces a directly proportional change in signal). After performing the initial calibration, the device performs a further, finer calibration. This involves taking a measurement (“calibration value”) of reflected light intensity for each zone whilst the test strip is dry—subsequent measurements (“test values”) are normalised by reference to the calibration value for the respective zones (i.e. normalised value=test value/calibration value). To conduct an assay, a sample receiving portion of the test strip is contacted with the liquid sample. In this case of a urine sample for instance, the sample receiving portion may be held in a urine stream, or a urine sample collected in a receptacle and the sample receiving portion briefly (about 5-10 seconds) immersed in the sample. Sampling may be performed whilst the test strip is inserted in the reader or, less preferably, the strip can be briefly removed from the reader for sampling and then reintroduced into the reader. Measurements of reflected light intensity from one or more (preferably all three) of the zones are then commenced, typically after a specific timed interval following insertion of the test strip into the reader. Desirably the measurements are taken at regular intervals (e.g. at between 1-10 second intervals, preferably at between 1-5 second intervals). The measurements are made as a sequence of many readings over short (10 milliseconds or less) periods of time, interleaved zone by zone, thereby minimising any effects due to variation of ambient light intensity which may penetrate into the interior of the reader housing. Example 2 This example described in greater detail the features of the preferred arrangement of LED's and photodiodes outlined in Example 1. FIG. 3 shows a plan view of an exemplary embodiment of an optical arrangement. In this embodiment, the optical arrangement include three light emitting diodes and two photodetectors. The active area (A) of the photodetectors (PD) is 1.5 mm×1.5 mm. The optics are arranged such that center lines of LED's 1 and 3 correspond to the center lines of PD 1 and PD2. The 3 LED's and two photodetectors are disposed within an area no larger than about 1 square cm, preferably no larger than about 0.7 square cm, specifically 1 cm×0.7 cm. Also shown is the position of the test-strip 30 that is positioned above the LED's. The test-strip is inserted so that the test and control lines 32 are situated above respectively LED's 1 and 3. The distance D, namely the distance between the PD and LED, is preferably large enough to prevent specular reflection of light emitted from the LED from the surface of the test-strip directly to the PD. This distance will be dependent upon various factors such as the size of the windows, as well as the distance between the windows and the LED's and will be best determined by routine experimentation. The windows are situated above the respective LED's that effectively define the areas through which light shines. In one exemplary embodiment, the dimensions of the window are 2 mm wide by 2.75 mm high. FIG. 4 is a schematic representation of the layout of the 3 LED/2 Photodiode optical system described in Example 1. FIG. 4 depicts an optics block component for accommodation within an assay result reading device that includes three LED's (LED 1, 2 and 3) and two photodetectors (PD1 and PD2). Light from LED 1 illuminates a test zone of a test strip (not shown) inserted into the reader. Light reflected from the test zone is detected by PD1. Light from LED3 illuminates a control zone of the test strip and light reflected therefrom is detected by PD2. Light from LED2 illuminates a reference zone of the test strip. Each LED is optically isolated by light-impermeable baffles 40, which ensure that each LED is capable of illuminating only its respective zone of the test strip. However the surfaces of the baffles facing LED2 are angled so as to allow both PD1 and PD2 to collect reflected light from the maximum area of the reference zone. FIG. 5 shows the spatial relationship between the LED and photodiode. The photodiode is positioned at a sufficient distance to ensure that it does not receive specular reflections from the front cover of the test-strip 30. Specular reflections are a direct reflection. Thus any light hitting the test-strip at an angle β will also reflect at the same angle. Thus to avoid the PD detecting specular light, it is offset. The degree of offset is dependent upon the height D2, the window opening width D1. The substrate 70 supporting the window is made from black plastic and is chosen to be at a particular angle γ. If the plastic were constructed so as to have a horizontal roof (as denoted dashed line 60), light from the LED could bounce of the roof and onto the PD. To avoid this the substrate is angled such that light hitting the angled part reflects directly back (as denoted by dashed line 62). Again this angle is dependent upon D1 and is approx 40% in the device shown by reference to the solid line 64. Finally the height of the divide is chosen to be a certain height such that light from the LED does not shine directly to the PD. The height of the divide will be determinant upon the height of the LED. In one exemplary embodiment, the LED height is 1.5 mm and the divide height 2 mm. In a preferred embodiment the test strip comprises of a layer of a porous carrier such as nitrocellulose sandwiched between two layers of plastic such as MYLAR®. The layer proximal to the light source must be permeable to light, preferably transparent. In the situation wherein the PD's and LED are situated on the same side of the test-strip the layer distal to the light source must be capable of reflecting light. It is preferable for this distal layer to be white to increase contrast and hence the signal to noise ratio. It is apparent that, in view of the inverse square law, it would generally be preferred to position the photodiodes as close as possible to the test strip (i.e. decrease x), so as to increase the signal intensity I. However, merely decreasing the vertical separation y between the photodiode and the test strip would increase angle θ, decreasing the value of cos θ and therefore tend to reduce the signal intensity. An alternative approach to improve signal intensity would be to re-position the photodiode nearer the center of the system, which would simultaneously decrease the reflection distance and the angle of reflection. However the distance must be minimized to ensure that the maximum intensity of light is detected (the intensity decreases as a function of the distance of the PD from the test-strip and the angle of reflection). Example 3 In one exemplary embodiment, the active area of the photodetector is 2 mm×2 mm. The light source provides light, at least some of which has a wavelength of 635 nm. The height of the test-strip above the light source is 5.5 mm. The wall height separating the LED's is 2.7 mm and the angle of the wall is 30 degrees. The plastic used is black nylon. Example 4 FIGS. 6-11 illustrate an exemplary embodiment of portions of an assay reader. FIG. 6 shows an exploded view of a baffle arrangement 100 and a printed circuit board (PCB) 102 that may receive the baffle arrangement. The baffle arrangement defines three windows 104 and includes a location feature 110 which may define an aperture 111 or some other feature that can engage a corresponding feature 112 on the PCB. The location feature 110 may also be so sized and shaped as to engage a mating feature on a test strip (not shown) when the test strip is introduced to the baffle arrangement. The strip may thus be locked into position during an assay measurement. The baffle arrangement also includes parallel raised side walls 114 that may guide the test strip into the correct location and ensure that it both engages with the location feature and is correctly linearly aligned with the windows 104 and not skewed. The PCB includes, among other item not shown, light sources such as light emitting diodes (LED's) 106 and light detectors such as photodiodes (PD's) 108. The LED's and PD's may be mounted in the same plane and positioned under the respective windows 104 such that light emitted from one or more LED's is able to pass through the window spaces onto the test-strip and be reflected back down onto one or more of the PD's. FIG. 7 shows a top plan view of an exemplary embodiment of a baffle arrangement 110 in which the light source centers 106a are aligned under their respective windows 104. FIG. 8 provides an underside view of baffle arrangement 100. The arrangement may include a number of mounting pins 118 to provide contact points with the PCB (not shown). Defining windows 104 are baffles 116 and side barriers 117 that have angled walls to screen light as described above. FIG. 9 shows a bottom plan view of the baffle arrangement 100. The light source centers 106a are aligned under windows 104, and light detector centers 108a are offset to provide the appropriate incident angle, as described above. FIG. 10 depicts a longitudinal cross-section (taken at line 10-10 in FIG. 7) of baffle arrangement 100 seated on PCB 102 and a test strip 120 raised from its normal position in the baffle arrangement. The light sources 106 are positioned in their respective windows 104. FIG. 11 is a transverse cross section (taken at line 11-11 in FIG. 10) showing the test strip 120 in position relative to the baffle arrangement 100. The strip includes a porous carrier membrane 122 in which the assay reaction is conducted. Light emanative from a light source 106 impinges on the membrane. Light emanating from the membrane is detected by the light detector 108. A divider 124 prevents light from source 106 from shining directly on detector 108. Example 5 An assay result reader according to the present disclosure may also include a system for declaring the result of an assay before completion of the assay, if a analyte measurement signal is above an upper threshold or below a lower threshold. Such systems are described in U.S. patent application Ser. No. 10/741,416, filed Dec. 19, 2003. Example 6 An assay result reader according to the present disclosure may also include a system for detecting flow rate of a fluid sample, such as one described in U.S. patent application Ser. No. 10/742,459, filed Dec. 19, 2003. Example 7 An assay result reader according to the present disclosure may further include both an early declaration system described in U.S. patent application Ser. No. 10/741,416 and a flow rate detection system described in U.S. patent application Ser. No. 10/742,459. All patents and patent applications mentioned herein are hereby incorporated by reference in their entirety as if each individual patent or application were specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control. | <SOH> FIELD <EOH>The disclosed subject matter relates to assay reading devices for the measurement of analytes. In particular it relates to electronic readers for use with assay test-strips which use optical methods of measurement. | <SOH> SUMMARY <EOH>The present disclosure provides inexpensive, typically disposable, assay readers either for use with, or in integral combination with, an assay test strip such as disclosed by EP291194. The optics are provided in a compact arrangement well-suited, for example, for a handheld device. The arrangement also provides an optimal or near optimal path length between the light source and photodetector thus establishing a strong signal. In some embodiments, an assay result reading device for reading the result of an assay performed using a test strip includes a light source capable of emitting light incident upon at least two spatially separated zones of the test strip, and a photodetector which detects light emanating from each of the two said zones. A photodetector which is used to detect light emanating from two distinct zones of the test strip, may be referred to as a “shared” photodetector. In some embodiments, an assay result reading device for reading the result of an assay performed using a test strip includes a light source capable of emitting light incident upon a zone of the test strip, and two photodetectors both of which are able to detect some of the light emanating from the zone of the test strip illuminated by the light source. Such a zone, “read” by two or more photodetectors, may be referred to as a “commonly read” zone. In other embodiments, the invention provides methods of reading the result of an assay performed using a test strip in accordance with the embodiments described above. | 20040401 | 20080101 | 20050217 | 72534.0 | 1 | GEISEL, KARA E | OPTICAL ARRANGEMENT FOR ASSAY READING DEVICE | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,217 | ACCEPTED | System and method for synchronizing operations among a plurality of independently clocked digital data processing devices | A system is described for maintaining synchrony of operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that distributes tasks to a synchrony group comprising a plurality of devices that are to perform the tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to the members of the synchrony group over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task. Each member of the synchrony group periodically obtains from the task distribution device an indication of the current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task. | 1. A system comprising a plurality of devices, one of the devices operating as a task source device and at least one other device operating as a member of a synchrony group, the task source device being configured to distribute a series of tasks to the synchrony group, each task being associated with a time stamp indicating a time, relative to a clock maintained by the task source device, at which the devices comprising the synchrony group are to execute the respective task. 2. A system as defined in claim 1 in which the synchrony group comprises a plurality of member devices. 3. A system as defined in claim 2 in which each device comprising a member of the synchrony group is further configured to execute each task that it receives from the task source device at the determined time. 4. A system as defined in claim 3 in which the member devices are configured to execute respective tasks in synchrony. 5. A system as defined in claim 2 in which one of the member devices operates as a master device configured to perform at least one type of synchrony group management operation. 6. A system as defined in claim 5 further including a user interface module configured to control the master device. 7-8. (canceled) 9. A system as defined in claim 5, the system comprising at least one additional device in which the master device is configured to enable the at least one additional device to join the synchrony group as a slave device. 10. A system as defined in claim 9 in which the task source device is configured to distribute tasks to the member devices using a selected multi-cast transmission methodology. 11-18. (canceled) 19. A system as defined in claim 5 in which the member device operating as the master device is configured to enable the master device to migrate from one member device to another member device in the system. 20. A system as defined in claim 5 in which the master device is configured to enable the task source device to migrate from one device to another device in the system. 21-30. (canceled) 31. A system as defined in claim 1 in which at least one member device is further configured to adjust its clock rate. 32. (canceled) 33. A system as defined in claim 1 in which at least one other device operates as a task source device configured to distribute tasks to a second synchrony group. 34-64. (canceled) 65. A device for executing a series of tasks provided by a task source at times specified by the task source in relation to a clock maintained by the task source, the device comprising: an interface module configured to receive the series of tasks; a current time retrieval module configured to obtain from the task source a current time value; an execution time determination module configured to determine a time at which the task is to be executed; and a task execution module configured to execute each respective task. 66. A device as defined in claim 65 further including a control module for controlling execution of commands received by said interface module. 67-85. (canceled) 86. A device as defined in claim 65 further including: a migration information receiving module configured to receive migration information from the task source device; and a migration control module configured to distribute the series of tasks to the synchrony group. 87-90. (canceled) 91. A device as defined in claim 65 further including a clock rate adjustment module configured to adjust the member device's clock rate. 92-108. (canceled) 109. A method of operating a system comprising the steps of distributing a series of tasks to a synchrony group, associating each of the tasks with a time stamp; indicating a time, relative to a clock maintained by a task source device, at which devices comprising the synchrony group are to execute the respective tasks. 110. A method as defined in claim 109 in which the synchrony group comprises a plurality of member devices. 111. A method as defined in claim 110 further comprising the step of enabling a member of the synchrony group to execute each task that it receives from the task source device at the a determined time. 112. A method as defined in claim 111 further comprising the step of enabling the member devices to execute respective tasks in synchrony. 113. A method as defined in claim 110 further comprising the step of enabling a member device to perform at least one type of synchrony group management operation. 114. A method as defined in claim 113 further comprising the step of controlling a master device's distribution of status information. 115-116. (canceled) 117. A method as defined in claim 109, further comprising the step of enabling at least one additional device to join the synchrony group as a slave device. 118. A method as defined in claim 110 further comprising the step of distributing tasks to the member devices using a selected multi-cast transmission methodology. 119-120. (canceled) 121. A method as defined in claim 109 further comprising the step of controlling the series of tasks to be distributed by the task source device. 122-126. (canceled) 127. A method as defined in claim 110 further comprising the step of migrating the function of one member device to another member device. 128. A method as defined in claim 127 further comprising the step of enabling the task source device to migrate from one device to another device in the system. 129-137. (canceled) 138. A method as defined in claim 109 further comprising the step of obtaining information associated with the tasks from at least two types of information sources. 139. A method as defined in claim 110 further comprising the step of adjusting the clock rate of a member device. 140. (canceled) 141. A method as defined in claim 109 further comprising the step of distributing tasks to a second synchrony group. 142-155. (canceled) 156. A method as defined in claim 109 further comprising the step of obtaining information associated with the tasks from a single information source. 157-200. (canceled) 201. A method of operating a device comprising the steps of: obtaining a series of tasks; determining a time at which each respective task is to be executed; and transmitting the series of tasks from the device to at least one other device. 202. A method as defined in claim 201 further comprising the step of utilizing a selected multi-cast transmission methodology. 203-205. (canceled) 206. A method as defined in claim 201 in which the series of tasks includes a series of task sequences. 207-217. (canceled) 218. A computer program for use in connection with a computer to provide a device for executing a series of tasks provided by a task source at times specified by the task source in relation to a clock maintained by the task source, the computer program comprising a computer-readable medium having encoded thereon: an interface module configured to enable the computer to receive the series of tasks, each task being associated with a time stamp, each time stamp indicating a time value; a current time retrieval module configured to enable the computer to obtain, from the task source, a current time values; an execution time determination module configured to enable the computer to determine, from the time stamp associated with each respective task a time at which the task is to be executed; and a task execution module configured to enable the computer to execute each respective task at the time determined by the execution time determination module. 219. A computer program as defined in claim 218 further including a control module for enabling said computer to control execution of commands received by the interface module. 220. (canceled) 221. A computer program as defined in claim 218 in which the series of tasks includes a series of task sequences. 222-228. (canceled) 229. A computer program product as defined in claim 219 in which, in response to control information to enable another device to become a member of the device's synchrony group, the control module enables the interface module to transmit a command to the other device to enable the other device to become a member of the synchrony group. 230-232. (canceled) 233. A computer program as defined in claim 218 in which the interface module is further configured to enable the computer to transmit the tasks to at least one other device. 234-243. (canceled) 244. A computer program as defined in claim 218 further including a clock rate adjustment module configured to enable the computer to adjust the device's clock rate. 245-548. (canceled) 549. The system of claim 1 wherein each member device is further configured to periodically obtain from the task source device an indication of a current time value indicated by the task source device's clock. 550. The system of claim 549 wherein each member device is further configured to determine, from the time stamp associated with each respective task and a time differential value representing a difference between the current time value indicated by the task source device's clock, and a current time value indicated by its respective clock, a time, relative to its respective clock, at which it is to execute the task. 551. The system of claim 6 wherein the master device is further configured to provide status information relating to the status of the synchrony group to the user interface module. 552. The system of claim 10 wherein the task source device is enabled to transmit at least one previously distributed task to the slave device using a selected unicast transmission methodology. 553. The system of claim 31 wherein the clock rate of the at least one member device is adjusted in relation to a clock rate value maintained by the task source device's clock. 554. The system of claim 33 wherein the device operating as the task source device for the first synchrony group is also operating as a member device of a second synchrony group. 555. The device of claim 86 wherein the migration control module is further configured to notify the members of the synchrony group that it is to thereafter operate as the task source device. 556. The method of claim 114 wherein the master device is further enabled to provide status information relating to the status of the synchrony group to the user interface module. 557. A system for synchronizing operations among a plurality of digital data processing devices comprising: at least one task distribution device configured to distribute tasks over a network; and at least one member device configured to perform the tasks in synchrony. 558. The system of claim 557 further comprising an interface module configured to control one or more synchrony groups. 559. The system of claim 558 wherein the user interface module is further configured to display visual images representative of the tasks being performed in synchrony. 560. The system of claim 559 wherein the user interface module further comprises a motion sensor configured to activate the user interface module when moved by a user. 561. The system of claim 560 wherein the user interface module further comprises a scroll wheel for the selection of the tasks to be performed in synchrony. 562. The system of claim 557 wherein the task distribution device is further configured to enable the at least one member device to initiate without appreciable delay the performance of the tasks in synchrony. 563. The system of claim 557 wherein the task distribution device is further configured to allow one or more additional member devices to join without appreciable delay or disengage without appreciable delay the at least one member device's synchronous performance. 564. The system of claim 557 wherein the at least one task distribution device is further configured to obtain information associated with the tasks from at least one information source. 565. The system of claim 557 wherein the at least one task distribution device is independently clocked. 566. The system of claim 557 wherein the at least one member device is independently clocked. 567. The system of claim 557 wherein each of the tasks is associated with a time stamp relative to a clock maintained by the at least one task distribution device. 568. The system of claim 557 wherein the tasks comprise audio tracks. 569. The system of claim 568 wherein the audio tracks are in a WMA format. 570. The system of claim 557 wherein the tasks comprise visual tracks. 571. The system of claim 557 wherein the tasks comprise audiovisual tracks. 572. The system of claim 564 wherein the at least one information source is an Apple iPod®. 573. The system of claim 564 wherein the at least one information source is an Internet broadcast. 574. The system of claim 564 wherein the at least one information source is a satellite broadcast. 575. The system of claim 567 wherein the time stamp represents when the at least one member device is to execute the task. 576. A system for synchronizing operations among a plurality of digital data processing devices comprising a zone player residing within one or more audio reproduction devices. | INCORPORATION BY REFERENCE This application claims the benefit of Provisional Patent Application Ser. No. 60/490,768, filed on Jul. 28, 2003, entitled “Method for Synchronizing Audio Playback Between Multiple Networked Devices,” assigned to the assignee of the present application, incorporated herein by reference. FIELD OF THE INVENTION The present invention relates generally to the field of digital data processing devices, and more particularly to systems and methods for synchronizing operations among a plurality of independently-clocked digital data processing devices. The invention is embodied in a system for synchronizing operations among a plurality of devices, in relation to information that is provided by a common source. One embodiment of the invention enables synchronizing of audio playback as among two or more audio playback devices that receive audio information from a common information source, or channel. More generally, the invention relates to the field of arrangements that synchronize output generated by a number of output generators, including audio output, video output, combinations of audio and video, as well as other types of output as will be appreciated by those skilled in the art, provided by a common channel. Generally, the invention will find utility in connection with any type of information for which synchrony among independently-clocked devices is desired. BACKGROUND OF THE INVENTION There are a number of circumstances under which it is desirable to maintain synchrony of operations among a plurality of independently-clocked digital data processing devices in relation to, for example, information that is provided thereto by a common source. For example, systems are being developed in which one audio information source can distribute audio information in digital form to a number of audio playback devices for playback. The audio playback devices receive the digital information and convert it to analog form for playback. The audio playback devices may be located in the same room or they may be distributed in different rooms in a residence such as a house or an apartment, in different offices in an office building, or the like. For example, in a system installed in a residence, one audio playback device may be located in a living room, while another audio playback device is be located in a kitchen, and yet other audio playback devices may be located in various bedrooms of a house. In such an arrangement, the audio information that is distributed to various audio playback devices may relate to the same audio program, or the information may relate to different audio programs. If the audio information source provides audio information relating to the same audio program to two or more audio playback devices at the same time, the audio playback devices will generally contemporaneously play the same program. For example, if the audio information source provides audio information to audio playback devices located in the living room and kitchen in a house at the same time, they will generally contemporaneously play the same program. One problem that can arise is to ensure that, if two or more audio playback devices are contemporaneously attempting to play back the same audio program, they do so simultaneously. Small differences in the audio playback devices' start times and/or playback speeds can be perceived by a listener as an echo effect, and larger differences can be very annoying. Differences can arise because for a number of reasons, including delays in the transfer of audio information over the network. Such delays can differ as among the various audio playback devices for a variety of reasons, including where they are connected into the network, message traffic and other reasons as will be apparent to those skilled in the art. Another problem arises from the following. When an audio playback device converts the digital audio information from digital to analog form, it does so using a clock that provides timing information. Generally, the audio playback devices that are being developed have independent clocks, and, if they are not clocking at precisely the same rate, the audio playback provided by the various devices can get out of synchronization. SUMMARY OF THE INVENTION The invention provides a new and improved system and method for synchronizing operations among a number of digital data processing devices that are regulated by independent clocking devices. Generally, the invention will find utility in connection with any type of information for which synchrony among devices connected to a network is desired. The invention is described in connection with a plurality of audio playback devices that receive digital audio information that is to be played back in synchrony, but it will be appreciated that the invention can find usefulness in connection with any kind of information for which coordination among devices that have independent clocking devices would find utility. In brief summary, the invention provides, in one aspect, a system for maintaining synchrony of operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that distributes tasks to a synchrony group comprising a plurality of devices that are to perform the tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to the members oft he synchrony group over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task. Each member oft he synchrony group periodically obtains from the task distribution device an indication oft he current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task. In one embodiment, the tasks that are distributed include audio information for an audio track that is to be played by all of the devices comprising the synchrony group synchronously. The audio track is divided into a series of frames, each of which is associated with a time stamp indicating the time, relative to the clock maintained by an audio information channel device, which, in that embodiment, serves as the task distribution device, at which the members of the synchrony group are to play the respective frame. Each member of the synchrony group, using a very accurate protocol, periodically obtains the time indicated by the audio information channel device, and determines a differential between the time as indicated by its local clock and the audio information channel device's clock. The member uses the differential and the time as indicated by the time stamp to determine the time, relative to its local clock, at which it is to play the respective frame. The members of the synchrony group do this for all of the frames, and accordingly are able to play the frames in synchrony. BRIEF DESCRIPTION OF THE DRAWINGS This invention is pointed out with particularity in the appended claims. The above and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: FIG. 1 schematically depicts an illustrative networked audio system, constructed in accordance with the invention; FIG. 2 schematically depicts a functional block diagram of a synchrony group utilizing a plurality of zone players formed within the networked audio system depicted in FIG. 1; FIG. 2A schematically depicts two synchrony groups, illustrating how a member of one synchrony group can provide audio information to the members of another synchrony group; FIG. 3 depicts an functional block diagram of a zone player for use in the networked audio system depicted in FIG. 1; and FIG. 4 is useful in understanding an digital audio information framing methodology useful in the network audio system depicted in FIG. 1. DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT FIG. 1 depicts an illustrative network audio system 10 constructed in accordance with the invention. With reference to FIG. 1, the network audio system 10 includes a plurality of zone players 11(1) through 11(N) (generally identified by reference numeral 11(n)) interconnected by a local network 12, all of which operate under control of one or more user interface modules generally identified by reference numeral 13. One or more of the zone players 11(n) may also be connected to one or more audio information sources, which will generally be identified herein by reference numeral 14(n)(s), and/or one or more audio reproduction devices, which will generally be identified by reference numeral 15(n)(r). In the reference numeral 14(n)(s), index “n” refers to the index “n” of the zone player 11(n) to which the audio information source is connected, and the index “s”(s=1, . . . ,Sn) refers to the “s-th” audio information source connected to that “n-th” zone player 11(n). Thus, if, for example, a zone player 11(n) is connected to four audio information sources 14(n)(1) through 14(n)(4), the audio information sources may be generally identified by reference numeral 14(n)(s), with Sn=4. It will be appreciated that the number of audio information sources Sn may vary as among the various zone players 11(n), and some zone players may not have any audio information sources connected thereto. Similarly, in the reference numeral 15(n)(r), index “n” refers to the index “n” of the zone player 11(n) to which the audio reproduction device is connected, and the index “r”(r=1, . . . ,Rn) refers to the “r-th” audio information source connected to that “n-th” zone player 11(n). In addition to the audio information sources 14(n)(s), the network audio system 10 may include one or more audio information sources 16(1) through 16(M) connected through appropriate network interface devices (not separately shown) to the local network 12. Furthermore, the local network may include one or more network interface devices (also not separately shown) that are configured to connect the local network 12 to other networks, including a wide area network such as the Internet, the public switched telephony network (PSTN) or other networks as will be apparent to those skilled in the art, over which connections to audio information sources may be established. The zone players 11(n) associated with system 10 may be distributed throughout an establishment such as residence, an office complex, a hotel, a conference hall, an amphitheater or auditorium, or other types of establishments as will be apparent to those skilled in the art or the like. For example, if the zone players 11(n) and their associated audio information source(s) and/or audio reproduction device(s) are distributed throughout a residence, one, such as zone player 11(1) and its associated audio information source(s) and audio reproduction device(s) may be located in a living room, another may be located in a kitchen, another may be located in a dining room, and yet others may be located in respective bedrooms, to selectively provide entertainment in those rooms. On the other hand, if the zone players 11(n) and their associated audio information source(s) and/or audio reproduction device(s) are distributed throughout an office complex, one may, for example, be provided in each office to selectively provide entertainment to the employees in the respective offices. Similarly, if the zone players 11(n) and associated audio information source(s) and/or audio reproduction device(s) are used in a hotel, they may be distributed throughout the rooms to provide entertainment to the guests. Similar arrangements may be used with zone players 11(n) and associated audio information source(s) and/or audio reproduction device(s) used in an amphitheater or auditorium. Other arrangements in other types of environments will be apparent to those skilled in the art. In each case, the zone players 11(n) can be used to selectively provide entertainment in the respective locations, as will be described below. The audio information sources 14(n)(s) and 16(m) may be any of a number of types of conventional sources of audio information, including, for example, compact disc (“CD”) players, AM and/or FM radio receivers, analog or digital tape cassette players, analog record turntables and the like. In addition, the audio information sources 14(n)(s) and 16(m) may comprise digital audio files stored locally on, for example, personal computers (PCs), personal digital assistants (PDAs), or similar devices capable of storing digital information in volatile or non-volatile form. As noted above, the local network 12 may also have an interface (not shown) to a wide area network, over which the network audio system 10 can obtain audio information. Moreover, one or more of the audio information sources 14(n)(s) may also comprise an interface to a wide area network such as the Internet, the public switched telephony network (PSTN) or any other source of audio information. In addition, one or more of the audio information sources 14(n)(s) and 16(m) may comprise interfaces to radio services delivered over, for example, satellite. Audio information obtained over the wide area network may comprise, for example, streaming digital audio information such as Internet radio, digital audio files stored on servers, and other types of audio information and sources as will be appreciated by those skilled in the art. Other arrangements and other types of audio information sources will be apparent to those skilled in the art. Generally, the audio information sources 14(n)(s) and 16(m) provide audio information associated with audio programs to the zone players for playback. A zone player that receives audio information from an audio information source 14(n)(s) that is connected thereto can provide playback and/or forward the audio information, along with playback timing information, over the local network 12 to other zone players for playback. Similarly, each audio information source 16(m) that is not directly connected to a zone player can transmit audio information over the network 12 to any zone player 11(n) for playback. In addition, as will be explained in detail below, the respective zone player 11(n) can transmit the audio information that it receives either from an audio information source 14(n)(s) connected thereto, or from an audio information source 16(m), to selected ones of the other zone players 11(n′), 11(n″), . . . (n not equal to n′, n″, . . . ) for playback by those other zone players. The other zone players 11(n′), 11(n″), . . . to which the zone player 11(n) transmits the audio information for playback may be selected by a user using the user interface module 13. In that operation, the zone player 11(n) will transmit the audio information to the selected zone players 11(n′), 11(n″), . . . over the network 12. As will be described below in greater detail, the zone players 11(n), 11(n′), 11(n″), . . . operate such that the zone players 11(n′), 11(n″), . . . synchronize their playback of the audio program with the playback by the zone player 11(n), so that the zone players 11(n), 11(n′), 11(n″) provide the same audio program at the same time. Users, using user interface module 13, may also enable different groupings or sets of zone players to provide audio playback of different audio programs synchronously. For example, a user, using a user interface module 13, may enable zone players 11(1) and 11(2) to play one audio program, audio information for which may be provided by, for example, one audio information source 14(1)(1). The same or a different user may, using the same or a different user interface module 13, enable zone players 11(4) and 11(5) to contemporaneously play another audio program, audio information for which may be provided by a second audio information source, such as audio information source 14(5)(2). Further, a user may enable zone player 11(3) to contemporaneously play yet another audio program, audio information for which may be provided by yet another audio information source, such as audio information source 16(1). As yet another possibility, a user may contemporaneously enable zone player 11(1) to provide audio information from an audio information source connected thereto, such as audio information source 14(1)(2), to another zone player, such as zone player 11(6) for playback. In the following, the term “synchrony group” will be used to refer to a set of one or more zone players that are to play the same audio program synchronously. Thus, in the above example, zone players 11(1) and 11(2) comprise one synchrony group, zone player 11(3) comprises a second synchrony group, zone players 11(4) and 11(5) comprise a third synchrony group, and zone player 11(6) comprises yet a fourth synchrony group. Thus, while zone players 11(1) and 11(2) are playing the same audio program, they will play the audio program synchronously. Similarly, while zone players 11(4) and 11(5) are playing the same audio program, they will play the audio program synchronously. On the other hand, zone players that are playing different audio programs may do so with unrelated timings. That is, for example, the timing with which zone players 11(1) and 11(2) play their audio program may have no relationship to the timing with which zone player 11(3), zone players 11(4) and 11(5), and zone player 11(6) play their audio programs. It will be appreciated that, since “synchrony group” is used to refer to sets of zone players that are playing the same audio program synchronously, zone player 11(1) will not be part of zone player 11(6)'s synchrony group, even though zone player 11(1) is providing the audio information for the audio program to zone player 11(6). In the network audio system 10, the synchrony groups are not fixed. Users can enable them to be established and modified dynamically. Continuing with the above example, a user may enable the zone player 11(1) to begin providing playback of the audio program provided thereto by audio information source 14(1)(1), and subsequently enable zone player 11(2) to join the synchrony group. Similarly, a user may enable the zone player 11(5) to begin providing playback of the audio program provided thereto by audio information source 14(5)(2), and subsequently enable zone player 11(4) to join that synchrony group. In addition, a user may enable a zone player to leave a synchrony group and possibly join another synchrony group. For example, a user may enable the zone player 11(2) to leave the synchrony group with zone player 11(1), and join the synchrony group with zone player 11(6). As another possibility, the user may enable the zone player 11(1) to leave the synchrony group with zone player 11(2) and join the synchrony group with zone player 11(6). In connection with the last possibility, the zone player 11(1) can continue providing audio information from the audio information source 14(1)(1) to the zone player 11(2) for playback thereby. A user, using the user interface module 13, can enable a zone player 11(n) that is currently not a member of a synchrony group to join a synchrony group, after which it will be enabled to play the audio program that is currently being played by that synchrony group. Similarly, a user, also using the user interface module 13, can enable a zone player 11(n) that is currently a member of one synchrony group, to disengage from that synchrony group and join another synchrony group, after which that zone player will be playing the audio program associated with the other synchrony group. For example, if a zone player 11(6) is currently not a member of any synchrony group, it, under control of the user interface module 13, can become a member of a synchrony group, after which it will play the audio program being played by the other members of the synchrony group, in synchrony with the other members of the synchrony group. In becoming a member of the synchrony group, zone player 11(6) can notify the zone player that is the master device for the synchrony group that it wishes to become a member of its synchrony group, after which that zone player will also transmit audio information associated with the audio program, as well as timing information, to the zone player 11(6). As the zone player 11(6) receives the audio information and the timing information from the master device, it will play the audio information with the timing indicated by the timing information, which will enable the zone player 11(6) to play the audio program in synchrony with the other zone player(s) in the synchrony group. Similarly, if a user, using the user interface module 13, enables a zone player 11(n) associated with a synchrony group to disengage from that synchrony group, and if the zone player 11(n) is not the master device of the synchrony group, the zone player 11(n) can notify the master device, after which the master device can terminate transmission of the audio information and timing information to the zone player 11(n). If the user also enables the zone player 11(n) to begin playing another audio program using audio information from an audio information source 14(n)(s) connected thereto, it will acquire the audio information from the audio information source 14(n)(s) and initiate playback thereof. If the user enables another zone player 11(n′) to join the synchrony group associated with zone player 11(n), operations in connection therewith can proceed as described immediately above. As yet another possibility, if a user, using the user interface module 13, enables a zone player 11(n) associated with a synchrony group to disengage from that synchrony group and join another synchrony group, and if the zone player is not the master device of the synchrony group from which it is disengaging, the zone player 11(n) can notify the master device of the synchrony group from which it is disengaging, after which that zone player will terminate transmission of audio information and timing information to the zone player 11(n) that is disengaging. Contemporaneously, the zone player 11(n) can notify the master device of the synchrony group that it (that is, zone player 11(n)) is joining, after which the master device can begin transmission of audio information and timing information to that zone player 11(n). The zone player 11(n) can thereafter begin playback oft he audio program defined by the audio information, in accordance with the timing information so that the zone player 11(n) will play the audio program in synchrony with the master device. As yet another possibility, a user, using the user interface module 13, may enable a zone player 11(n) that is not associated with a synchrony group, to begin playing an audio program using audio information provided to it by an audio information source 14(n)(s) connected thereto. In that case, the user, also using the user interface module 13 or a user interface device that is specific to the audio information source 14(n)(s), can enable the audio information source 14(n)(s) to provide audio information to the zone player 11(n). After the zone player 11(n) has begun playback, or contemporaneously therewith, the user, using the user interface module 13, can enable other zone players 11(n′), 11(n″), . . . to join zone player 11(n)'s synchrony group and enable that zone player 11(n) to transmit audio information and timing information thereto as described above, to facilitate synchronous playback of the audio program by the other zone players 11(n′), 11(n″). . . . A user can use the user interface module 13 to control other aspects of the network audio system 10, including but not limited to the selection of the audio information source 14(n)(s) that a particular zone player 11(n) is to utilize, the volume of the audio playback, and so forth. In addition, a user may use the user interface module 13 to turn audio information source(s) 14(n)(s) on and off and to enable them to provide audio information to the respective zone players 11(n). Operations performed by the various devices associated with a synchrony group will be described in connection with FIG. 2, which schematically depicts a functional block diagram of a synchrony group in the network audio system 10 described above in connection with FIG. 1. With reference to FIG. 2, a synchrony group 20 includes a master device 21 and zero or more slave devices 22(1) through 22(G) (generally identified by reference numeral 22(g)), all of which synchronously play an audio program provided by an audio information channel device 23. Each of the master device 21, slave devices 22(g) and audio information channel device 23 utilizes a zone player 11(n) depicted in FIG. 1, although it will be clear from the description below that a zone player may be utilized both for the audio information channel device for the synchrony group 20, and the master device 21 or a slave device 22(g) of the synchrony group 20. As will be described below in more detail, the audio information channel device 23 obtains the audio information for the audio program from an audio information source, adds playback timing information, and transmits the combined audio and playback timing information to the master device 21 and slave devices 22(g) over the network 12 for playback. The playback timing information that is provided with the audio information, together with clock timing information provided by the audio information channel device 23 to the various devices 21 and 22(g) as will be described below, enables the master device 21 and slave devices 22(g) of the synchrony group 20 to play the audio information simultaneously. The master device 21 and the slave devices 22(g) receive the audio and playback timing information, as well as the clock timing information, that are provided by the audio information channel device 23, and play back the audio program defined by the audio information. The master device 21 is also the member of the synchrony group 20 that communicates with the user interface module 13 and that controls the operations of the slave devices 22(g) in the synchrony group 20. In addition, the master device 21 controls the operations of the audio information channel device 23 that provides the audio and playback timing information for the synchrony group 20. Generally, the initial master device 21 for the synchrony group will be the first zone player 11(n) that a user wishes to play an audio program. However, as will be described below, the zone player 11(n) that operates as the master device 21 can be migrated from one zone player 11(n) to another zone player 11(n′), which preferably will be a zone player that is currently operating as a slave device 22(g) in the synchrony group. In addition, under certain circumstances, as will be described below, the zone player 11(n) that operates as the audio information channel device 23 can be migrated from one zone player to another zone player, which also will preferably will be a zone player that is currently operating as a member of the synchrony group 20. It will be appreciated that the zone player that operates as the master device 21 can be migrated to another zone player independently of the migration of the audio information channel device 23. For example, if one zone player 11(n) is operating as both the master device 21 and the audio information channel device 23 for a synchrony group 20, the master device 21 can be migrated to another zone player 11(n′) while the zone player 11(n) is still operating as the audio information channel device 23. Similarly, if one zone player 11(n) is operating as both the master device 21 and the audio information channel device 23 for a synchrony group 20, the audio information channel device 23 can be migrated to another zone player 11(n′) while the zone player 11(n) is still operating as the master device 21. In addition, if one zone player 11(n) is operating as both the master device 21 and the audio information channel device 23 for a synchrony group 20, the master device 21 can be migrated to another zone player 11(n′) and the audio information channel device can be migrated to a third zone player 11(n″). The master device 21 receives control information from the user interface module 13 for controlling the synchrony group 20 and provides status information indicating the operational status of the synchrony group to the user interface module 13. Generally, the control information from the user interface module 13 enables the master device 21 to, in turn, enable the audio information channel device 23 to provide audio and playback timing information to the synchrony group to enable the devices 21 and 22(g) that are members of the synchrony group 20 to play the audio program synchronously. In addition, the control information from the user interface module 13 enables the master device 21 to, in turn, enable other zone players to join the synchrony group as slave devices 22(g) and to enable slave devices 22(g) to disengage from the synchrony group. Control information from the user interface module 13 can also enable the zone player 11(n) that is currently operating as the master device 21 to disengage from the synchrony group, but prior to doing so that zone player will enable the master device 21 to transfer from that zone player 11(n) to another zone player 11(n′), preferably to a zone player 11(n′) that is currently a slave device 22(g) in the synchrony group 20. The control information from the user interface module 13 can also enable the master device 21 to adjust its playback volume and to enable individual ones of the various slave devices 22(g) to adjust their playback volumes. In addition, the control information from the user interface module 13 can enable the synchrony group 20 to terminate playing of a current track of the audio program and skip to the next track, and to re-order tracks in a play list of tracks defining the audio program that is to be played by the synchrony group 20. The status information that the master device 21 may provide to the user interface module 13 can include such information as a name or other identifier for the track of the audio work that is currently being played, the names or other identifiers for upcoming tracks, the identifier of the zone player 11(n) that is currently operating as the master device 21, and identifiers of the zone players that are currently operating as slave devices 22(g). In one embodiment, the user interface module 13 includes a display (not separately shown) that can display the status information to the user. It will be appreciated that the zone player 11(n) that is operating as the audio information channel device 23 for one synchrony group may also comprise the master device 21 or any of the slave devices 22(g) in another synchrony group. This may occur if, for example, the audio information source that is to provide the audio information that is to be played by the one synchrony group is connected to a zone player also being utilized as the master device or a slave device for the other synchrony group. This will be schematically illustrated below in connection with FIG. 2A. Since, as noted above, the zone player 11(n) that is operating as the audio information channel device 23 for the synchrony group 20 may also be operating as a master device 21 or slave device 22(g) for another synchrony group, it can also be connected to one or more audio reproduction devices 15(n)(r), although that is not depicted in FIG. 2. Since the master device 21 and slave devices 22(g) are all to provide playback of the audio program, they will be connected to respective audio reproduction devices 15(n)(r). Furthermore, it will be appreciated that one or more of the zone players 11(n) that operate as the master device 21 and slave devices 22(g) in synchrony group 20 may also operate as an audio information channel device for that synchrony group or for another synchrony group and so they may be connected to one or more audio information sources 14(n)(s), although that is also not depicted in FIG. 2. In addition, it will be appreciated that a zone player 11(n) can also operate as a audio information channel device 23 for multiple synchrony groups. If the audio information channel device 23 does not utilize the same zone player as the master device 21, the master device 21 controls the audio information channel device by exchanging control information over the network 12 with the audio information channel device 23. The control information is represented in FIG. 2 by the arrow labeled CHAN_DEV_CTRL_INFO. The control information that the master device 21 provides to the audio information channel device 23 will generally depend on the nature of the audio information source that is to provide the audio information for the audio program that is to be played and the operation to be enabled by the control information. If, for example, the audio information source is a conventional compact disc, tape, or record player, broadcast radio receiver, or the like, which is connected to a zone player 11(n), the master device 21 may merely enable the zone player serving as the audio information channel device 23 to receive the audio information for the program from the audio information source. It will be appreciated that, if the audio information is not in digital form, the audio information channel device 23 will convert it to digital form and provide the digitized audio information, along with the playback timing information, to the master device 21 and slave devices 22(g). On the other hand, if the audio information source is, for example, a digital data storage device, such as may be on a personal computer or similar device, the master device 21 can provide a play list to the audio information channel device 23 that identifies one or more files containing the audio information for the audio program. In that case, the audio information channel device 23 can retrieve the files from the digital data storage device and provide them, along with the playback timing information, to the master device 21 and the slave devices 22(g). It will be appreciated that, in this case, the audio information source may be directly connected to the audio information channel device 23, as, for example, an audio information source 14(n)(s), or it may comprise an audio information source 16(m) connected to the network 12. As a further alternative, if the audio information source is a source available over the wide area network, the master device 21 can provide a play list comprising a list of web addresses identifying the files containing the audio information for the audio program that is to be played, and in that connection the audio information channel device 23 can initiate a retrieval of the files over the wide area network. As yet another alternative, if the audio information source is a source of streaming audio received over the wide area network, the master device 21 can provide a network address from which the streaming audio can be received. Other arrangements by which the master device 21 can control the audio information channel device 23 will be apparent to those skilled in the art. The master device 21 can also provide control information to the synchrony group's audio information channel device 23 to enable a migration from one zone player 11(n) to another zone player 11(n′). This may occur if, for example, the audio information source is one of audio information sources 16 or a source accessible over the wide area network via the network 12. The master device 21 can enable migration of the audio information channel device 23 for several reasons, including, for example, to reduce the loading of the zone player 11(n), to improve latency of message transmission in the network 12, and other reasons as will be appreciated by those skilled in the art. As noted above, the audio information channel device 23 provides audio and playback timing information for the synchrony group to enable the master device 21 and slave devices 22(g) to play the audio program synchronously. Details of the audio and playback timing information will be described in detail below in connection with FIGS. 3 and 4, but, in brief, the audio information channel device 23 transmits the audio and playback timing information in messages over the network 12 using a multi-cast message transmission methodology. In that methodology, the audio information channel device 23 will transmit the audio and playback timing information in a series of messages, with each message being received by all of the zone players 11(n) comprising the synchrony group 20, that is, by the master device 21 and the slave devices 22(g). Each of the messages includes a multi-cast address, which the master device 21 and slave devices 22(g) will monitor and, when they detect a message with that address, they will receive and use the contents of the message. The audio and playback timing information is represented in FIG. 2 by the arrow labeled “AUD+PBTIME_INFO,” which has a single tail, representing a source for the information at the audio information channel device 23, and multiple arrowheads representing the destinations of the information, with one arrowhead extending to the master device 21 and other arrowheads extending to each of the slave devices 22(g) in the synchrony group 20. The audio information channel device 23 may make use of any convenient multi-cast message transmission methodology in transmitting the audio and playback timing information to the synchrony group 20. As will be described in detail in connection with FIG. 4, the audio and playback timing information is in the form of a series of frames, with each frame having a time stamp. The time stamp indicates a time, relative to the time indicated by a clock maintained by the audio information channel device 23, at which the frame is to be played. Depending on the size or sizes of the messages used in the selected multi-cast message transmission methodology and the size or sizes of the frames, a message may contain one frame, or multiple frames, or, alternatively, a frame may extend across several messages. The audio information channel device 23 also provides clock time information to the master device 21 and each of the slave devices 22(g) individually over network 12 using a highly accurate clock time information transmission methodology. The distribution of the clock time information is represented in FIG. 2 by the arrows labeled “AICD_CLK_INF (M)” (in the case of the clock time information provided to the master device 21) and “AICD_CLK_INF (M)” through “AICD_CLK_INF (SG)” (in the case of audio information channel device clock information provided to the slave devices 22(g)). In one embodiment, the master device 21 and slave devices 22(g) make use of the well-known SNTP (Simple Network Time Protocol) to obtain current clock time information from the audio information channel device 23. The SNTP makes use of a unicast message transfer methodology, in which one device, such as the audio information channel device 23, provides clock time information to a specific other device, such as the master device 21 or a slave device 22(g), using the other device's network, or unicast, address. Each of the master device 21 and slave devices 22(g) will periodically initiate SNTP transactions with the audio information channel device 23 to obtain the clock time information from the audio information channel device 23. As will be described below in more detail, the master device 21 and each slave device 22(g) make use oft he clock time information to determine the time differential between the time indicated by the audio information channel device's clock and the time indicated by its respective clock, and use that time differential value, along with the playback time information associated with the audio information and the respective device's local time as indicated by its clock to determine when the various frames are to be played. This enables the master device 21 and the slave devices 22(g) in the synchrony group 20 to play the respective frames simultaneously. As noted above, the control information provided by the user to the master device 21 through the user interface module 13 can also enable the master device 21 to, in turn, enable another zone player 11(n′) to join the synchrony group as a new slave device 22(g). In that operation, the user interface module 13 will provide control information, including the identification of the zone player 11(n′) that is to join the synchrony group to the master device 21. After it receives the identification of the zone player 11(n′) that is to join the synchrony group, the master device 21 will exchange control information, which is represented in FIG. 2 by the arrows labeled SLV_DEV_CTRL_INF (S1) through SLV_DEV_CTRL_INF (SG) group slave control information, over the network 12 with the zone player 11(n′) that is identified in the control information from the user interface module 13. The control information that the master device 21 provides to the new zone player 11(n′) includes the network address of the zone player 11(n) that is operating as the audio information channel device 23 for the synchrony group, as well as the multi-cast address that the audio information channel device 23 is using to broadcast the audio and playback timing information over the network. The zone player that is to operate as the new slave device 22(g′) uses the multi-cast address to begin receiving the multi-cast messages that contain the audio information for the audio program being played by the synchrony group. It will be appreciated that, if the zone player 11(n) that is operating as the master device 21 for the synchrony group 20 is also operating the audio information channel device 23, and if there are no slave devices 22(g) in the synchrony group 20, the audio information channel device 23 may not be transmitting audio and playback timing information over the network. In that case, if the new slave device 22(g′) is the first slave device in the synchrony group, the zone player 11(n) that is operating as both the master device 21 and audio information channel device 23, can begin transmitting the audio and playback timing information over the network 12 when the slave device 22(g′) is added to the synchrony group 20. The zone player 11(n) can maintain a count of the number of slave devices 22(g) in the synchrony group 20 as they join and disengage, and, if the number drops to zero, it can stop transmitting the audio and playback timing information over the network 12 to reduce the message traffic over the network 12. The new slave device 22(g′) added to the synchrony group 20 uses the network address of the audio information channel device 23 for several purposes. In particular, the new slave device 22(g′) will, like the master device 21 (assuming the zone player 11(n) operating as the master device 21 is not also the audio information channel device 23), engage in SNTP transactions with the audio information channel device 23 to obtain the clock timing information from the audio information channel device 23. In addition, the new slave device 22(g′) can notify the audio information channel device 23 that it is a new slave device 22(g′) for the synchrony group 20 and provide the audio information channel device 23 with its network address. As will be described below, in one embodiment, particularly in connection with audio information obtained from a source, such as a digital data storage device, which can provide audio information at a rate that is faster than the rate at which it will be played, the audio information channel device 23 will buffer audio and timing information and broadcast it over the network 12 to the synchrony group 20 generally at a rate at which it is provided by the source. Accordingly, when a new slave device 22(g′)joins the synchrony group 20, the playback timing information may indicate that the audio information that is currently being broadcast by the audio information channel device 23 using the multi-cast methodology is to be played back some time in the future. To reduce the delay with which the new slave device 22(g′) will begin playback, the audio information channel device 23 can also retransmit previously transmitted audio and timing information that it had buffered to the new slave device 22(g′) using the unicast network address of the slave device 22(g′). The master device 21 can also use the slave device control information exchanged with the slave devices 22(g) for other purposes. For example, the master device 21 can use the slave device control information to initiate a migration of the master from its zone player 11(n) to another zone player 11(n′). This may occur for any of a number of reasons, including, for example, that the master device 21 is terminating playback by it of the audio program and is leaving the synchrony group 20, but one or more of the other devices in the synchrony group is to continue playing the audio program. The master device 21 may also want to initiate a migration if it is overloaded, which can occur if, for example, the zone player 11(n) that is the master device 21 for its synchrony group is also operating as an audio information channel device 23 for another synchrony group. The user can also use the user interface module 13 to adjust playback volume by the individual zone players 11(n) comprising the synchrony group. In that operation, the user interface module 13 provides information identifying the particular device whose volume is to be adjusted, and the level at which the volume is to be set to the master device 21. If the device whose volume is to be adjusted is the master device 21, the master device 21 can adjust its volume according to the information that it receives from the user interface module 13. On the other hand, if the device whose volume is to be adjusted is a slave device 22(g), the master device 21 can provide group slave control information to the respective slave device 22(g), to enable it to adjust its volume. The user can also use the user interface module 13 to enable a synchrony group 20 to cancel playing of the track in an audio program that is currently being played, and to proceed immediately to the next track. This may occur, for example, if the tracks for the program is in the form of a series of digital audio information files, and the user wishes to cancel playback of the track that is defined by one of the files. In that case, when the master device 21 receives the command to cancel playback of the current track, it will provide channel device control information to the audio information channel device 23 so indicating. In response, the audio information channel device 23 inserts control information into the audio and playback timing information, which will be referred to as a “resynchronize” command. In addition, the audio information channel device 23 will begin transmitting audio information for the next track, with timing information to enable it to be played immediately. The resynchronize command can also enable playback of a track to be cancelled before it has been played. Details of these operations will be described below. As noted above, there may be multiple synchrony groups in the network audio system 10, and further that, for example, a zone player 11(n) may operate both as a master device 21 or a slave device 22(g) in one synchrony group, and as the audio information channel device 23 providing audio and playback timing information and clock timing information for another synchrony group. An illustrative arrangement of this will be described in connection with FIG. 2A. With reference to FIG. 2A, that FIG. depicts elements of two synchrony groups, identified by reference numerals 20(1) and 20(2), respectively. For clarity, FIG. 2A does not show a number of elements, the presence of which would be evident from FIGS. 1 and 2 as described above. For example, FIG. 2A does not depict the audio information sources from which audio information is obtained for the synchrony groups or the audio reproduction devices that are used to produce sound for the master and slave devices, which are depicted in both FIGS. 1 and 2. In addition, FIG. 2A does not depict arrows that represent control information provided by the respective master devices to the slave devices in the respective synchrony groups, or to the audio information channel devices that provide audio and timing information for the respective synchrony groups, which are depicted in FIG. 2. In addition, FIG. 2A does not depict the arrows that represent the clock timing information provided by the audio information channel devices to the respective members of the respective synchrony groups, which are also depicted in FIG. 2. As will be noted below, however, FIG. 2A does depict arrows representing the audio and playback timing information provided by the respective audio information channel devices for the respective synchrony groups 20(1), 20(2), to the master and slave devices comprising the respective synchrony groups 20(1), 20(2). Each synchrony group 20(1), 20(2) comprises elements of a number of zone players. A functional block diagram of a zone player will be described below in connection with FIG. 3. Synchrony group 20(1) includes a master device 21(1) and “K” slave devices 22(1)(1) through 22(K)(1) (the index “1” in reference numeral 21(1) and the last index in reference numeral 22(1)(1) through 21(K)(1) corresponds to the index of the synchrony group 20(1) to which they belong) utilize zone players 11(1) and 11(K+1) respectively. Similarly, synchrony group 20(2) includes a master device 21(2) and “L” slave devices 22(1)(2) through 22(L)(2) that utilize zone players 11(K+2) through 11(K+L+2). In the illustrative arrangement depicted in FIG. 2A, both synchrony groups 20(1) and 20(2) are controlled by the user interface module 13, which can provide control information to, and receive status information from, the master devices 21(1) and 21(2) independently. It will be appreciated that separate user interface modules may be provided to provide control information to, and receive status information from, the respective master devices 21(1), 21(2). As noted above, the slave device 22(1)(2) in synchrony group 20(2) utilizes zone player 11(K+3). In the illustrative arrangement depicted in FIG. 2A, the audio information channel device 23(1) that provides audio and playback timing information to the master and slave devices 21(1), 22(1)(1), . . . , 22(K)(1) of synchrony group 20(1) also utilizes zone player 11(K+3). As noted above, this may occur if, for example, the audio information source that is to provide audio information to be played by the synchrony group 20(1) is connected to the zone player 11(K+3). Thus, when the master device 21(1) of synchrony group 20(1) exchanges channel device control information with the audio information channel device 23(1), it is effectively exchanging channel device control information with the zone player 11(K+3). Similarly, when the master and slave devices 21(1), 22(1)(1), . . . , 22(K)(1) of synchrony group 20(1) receive audio and playback timing information, as well as clock timing information, from the audio information channel device 23(1), they are effectively receiving the information from the zone player 11(K+3). FIG. 2A depicts a multi-headed arrow representing audio and playback timing information transmitted by the zone player 11(K+3), as audio information channel device 23(1), to the master and slave devices 21(1), 22(1)(1), . . . ,11(K)(1) comprising synchrony group 20(1). On the other hand, in the illustrative arrangement depicted in FIG. 2A, the synchrony group 20(2) utilizes a zone player 11(K+L+3) as its audio information channel device 23(2). As with synchrony group 20(1), when the master device 21(2) of synchrony group 20(2) exchanges channel device control information with the audio information channel device 23(2), it is effectively exchanging channel device control information with the zone player 11(K+L+3). Similarly, when the master and slave devices 21(2), 22(1)(2), . . . , 22(L)(2) of synchrony group 20(2) receive audio and playback timing information, as well as clock timing information, from the audio information channel device 23(2), they are effectively receiving the information from the zone player 11(K+L+3). FIG. 2A depicts a multi-headed arrow representing audio and playback timing information transmitted by the zone player 11(K+3) as audio information channel device 23(2) to the master and slave devices 21(2), 22(1)(2), . . . ,22(L)(2) comprising synchrony group 20(2). In the illustrative arrangement depicted in FIG. 2A, zone player 11(K+L+3), which is the audio information channel device 23(2) for synchrony group 20(2), is not shown as being either a master or a slave device in another synchrony group. However, it will be appreciated that zone player 11(K+L+3) could also be utilized as the master device or a slave device for another synchrony group. Indeed, it will be appreciated that the zone player that is utilized as the audio information channel device for synchrony group 20(2) may also be a zone player that is utilized as the master device 21(1) or a slave device 22(1)(1), . . . , 22(K)(1) in the synchrony group 20(1). A zone player 11(n) that is utilized as a member of one synchrony group may also be utilized as the audio information channel device for another synchrony group if the audio information source that is to supply the audio information that is to be played by the other synchrony group is connected to that zone player 11(n). A zone player 11(n) may also be utilized as the audio information channel device for the other synchrony group if, for example, the audio information source is an audio information source 16(m) (FIG. 1) that is connected to the network 12 or an audio information source that is available over a wide area network such as the Internet. The latter may occur if, for example, the zone player 11(n) has sufficient processing power to operate as the audio information channel device and it is in an optimal location in the network 12, relative to the zone players comprising the other synchrony group (that is the synchrony group for which it is operating as audio information channel device) for providing the audio and playback timing information to the members of the other synchrony group. Other circumstances under which the zone player 11(n) that is utilized as a member of one synchrony group may also be utilized as the audio information channel device for another synchrony group will be apparent to those skilled in the art. As was noted above, the master device 21 for a synchrony group 20 may be migrated from one zone player 11(n) to another zone player 11(n′). As was further noted above, the audio information channel device 23 for a synchrony group 20 may be migrated from one zone player 11(n) to another zone player 11(n′). It will be appreciated that the latter may occur if, for example, the audio information source that provides the audio program for the synchrony group is not connected to the zone player 11(n) that is operating as the audio information channel device 23, but instead is one of the audio information sources 16(m) connected to the network 12 or a source available over a wide area network such as the Internet. Operations performed during a migration of an audio information channel device 23 from one zone player 11(n) to another zone player 11(n′) will generally depend on the nature of the audio information that is being channeled by the audio information channel device 23. For example, if the audio information source provides streaming audio, the zone player 11(n) that is currently operating as the audio information channel device 23 for the synchrony group 20, can provide the following information to the other zone player 11(n′) that is to become the audio information channel device 23 for the synchrony group 20: (a) the identification of the source of the streaming audio information, (b) the time stamp associated with the frame that the zone player 11(n) is currently forming, and (c) the identifications of the zone players that are operating as the master device 21 and slave devices 22(g) comprising the synchrony group 20. After the zone player 11(n′) receives the information from the zone player 11(n), it will begin receiving the streaming audio from the streaming audio information source identified by the zone player 11(n), assemble the streaming audio information into frames, associate each frame with a time stamp, and transmit the resulting audio and playback timing information over the network 12. The zone player 11(n′) will perform these operations in the same manner as described above, except that, instead of using the time indicated by its digital to analog converter clock 34 directly in generating the time stamps for the frames, the initial time stamp will be related to the value of the time stamp that is provided by the zone player 11(n) (reference item (b) above), with the rate at which the time stamps are incremented corresponding to the rate at which its (that is, the zone player 11(n′)'s) clock increments. In addition, the zone player 11(n′) will notify the zone players that are operating as the master device 21 and slave devices 22(g) of the synchrony group 20 that it is the new audio information channel device 23 for the synchrony group 20, and provide the multi-cast address that it will be using to multi-cast the audio and playback timing information, as well as its unicast network address. After the members of the synchrony group 20 receive the notification from the zone player 11(n′) indicating that it is the new audio information channel device 23 for the synchrony group 20, they will receive the audio and playback timing information from the zone player 11(n′) instead of the zone player 11(n), using the multi-cast address provided by the zone player 11(n′). In addition, they can utilize the zone player 11(n′)'s unicast network address to obtain current time information therefrom. It will be appreciated that the zone player 11(n′) will determine its current time in relation to the time stamp that is provided by the zone player 11(n) (reference item (b) above) or the current time information that it received from the zone player 11(n) using the SNTP protocol as described above. Generally similar operations can be performed in connection with migrating the audio information channel device from one zone player 11(n) to another zone player 11(n′) if the audio information is from one or more audio information files, such as may be the case if the audio information comprises MP3 or WAV files that are available from sources such as sources 16(m) connected to the network 12 or over from sources available over a wide area network such as the Internet, except for differences to accommodate the fact that the audio information is in files. In that case, the zone player 11(n) that is currently operating as the audio information channel device 23 for the synchrony group 20 can provide the following information to the zone player 11(n′) that is to become the audio information channel device 23 for the synchrony group 20: (d) a list of the audio information files containing the audio information that is to be played; (e) the identification of the file for which the zone player 11(n) is currently providing audio and playback timing information, along with the offset into the file for which the current item of audio and playback timing information is being generated and the time stamp that the zone player 11(n) is associating with that frame, and (f) the identifications of the zone players that comprise the master device 21 and slave devices 22(g) comprising the synchrony group 20. After the zone player 11(n′) receives the information from the zone player 11(n), it will begin retrieving audio information from the file identified in item (e), starting at the identified offset. In addition, the zone player 11(n′) can assemble the retrieved audio information into frames, associate each frame with a time stamp and transmit the resulting audio and playback timing information over the network 12. The zone player 11(n′) will perform these operations in the same manner as described above, except that, instead of using the time indicated by its digital to analog converter clock 34 directly in generating the time stamps for the frames, the value of the initial time stamp will be related to the time stamp that is provided by the zone player 11(n) (reference item (e) above), with the rate at which the time stamps are incremented corresponding to the rate at which its (that is, the zone player 11(n′)'s) clock increments. In addition, the zone player 11(n′) will notify the zone players that are operating as the master device 21 and slave devices 22(g) of the synchrony group 20 that it is the new audio information channel device 23 for the synchrony group 20, and provide the multi-cast address that it will be using to multi-cast the audio and playback timing information, as well as its unicast network address. After the members of the synchrony group 20 receive the notification from the zone player 11(n′) indicating that it is the new audio information channel device 23 for the synchrony group 20, they will receive the audio and playback timing information from the zone player 11(n′) instead of the zone player 11(n), using the multi-cast address provided by the zone player 11(n′). In addition, they can utilize the zone player 11(n′)'s unicast network address to obtain current time information therefrom. It will be appreciated that the zone player 11(n′) will determine its current time in relation to the time stamp that is provided by the zone player 11(n) (reference item (b) above) or the current time information that it received from the zone player 11(n) using the SNTP protocol as described above. The zone player 11(n′) will process successive audio information files in the list that it receives from the zone player 11(n) (reference item (d)). Operations performed by the zone players 11(n) and 11(n′) in connection with migration of the audio information channel device 23 for other types of audio information will be apparent to those skilled in the art. In any case, preferably, the zone player 11(n) will continue operating as an audio information channel device 23 for the synchrony group 20 for at least a brief time after it notifies the zone player 11(n′) that it is to become audio information channel device for the synchrony group, so that the zone player 11(n′) will have time to notify the zone players in the synchrony group 20 that it is the new audio information channel device 23 for the synchrony group. Before proceeding further in describing operations performed by the network audio system 10, it would be helpful to provide a detailed description of a zone player 11(n) constructed in accordance with the invention. FIG. 3 depicts a functional block diagram of a zone player 11(n) constructed in accordance with the invention. All of the zone players in the network audio system 10 may have similar construction. With reference to FIG. 3, the zone player 11(n) includes an audio information source interface 30, an audio information buffer 31, a playback scheduler 32, a digital to analog converter 33, an audio amplifier 35, an audio reproduction device interface 36, a network communications manager 40, and a network interface 41, all of which operate under the control of a control module 42. The zone player 11(n) also has a device clock 43 that provides timing signals that control the general operations of the zone player 11(n). In addition, the zone player 11(n) includes a user interface module interface 44 that can receive control signals from the user interface module 13 (FIGS. 1 and 2) for controlling operations of the zone player 11(n), and provide status information to the user interface module 13. Generally, the audio information buffer 31 buffers audio information, in digital form, along with playback timing information. If the zone player 11(n) is operating as the audio information channel device 23 (FIG. 2) for a synchrony group 20, the information that is buffered in the audio information buffer 31 will include the audio and playback timing information that will be provided to the devices 21 and 22(g) in the synchrony group 20. If the zone player 11(n) is operating as the master device 21 or a slave device 22(g) for a synchrony group, the information that is buffered in the audio information buffer 31 will include the audio and playback timing information that the zone player 11(n) is to play. The audio information buffer 31 can receive audio and playback timing information from two sources, namely, the audio information source interface 30 and the network communications manager 40. In particular, if the zone player 11(n) is operating as the audio information channel device 23 for a synchrony group 20, and if the audio information source is a source 14(n)(s) connected to the zone player 11(n), the audio information buffer 31 will receive and buffer audio and playback timing information from the audio information source interface 30. On the other hand, if the zone player 11(n) is operating as the audio information channel device 23 for a synchrony group 20, and if the audio information source is a source 16(m) connected to the network 12, or a source available over the wide area network, the audio information buffer 31 will receive and buffer audio and playback timing information from the network communications manager 40. It will be appreciated that, if the zone player 11(n) is not a member of the synchrony group, the zone player 11(n) will not play this buffered audio and playback timing information. On yet another hand, if the zone player 11(n) is operating as the master device 21 or a slave device 22(g) in a synchrony group, and if the zone player 11(n) is not also the audio information channel device 23 providing audio and playback timing information for the synchrony group 20, the audio information buffer 31 will receive and buffer audio and playback timing information from the network communications manager 40. The audio information source interface 30 connects to the audio information source(s) 14(n)(s) associated with the zone player 11(n). While the zone player 11(n) is operating as audio information channel device 23 for a synchrony group 20, and if the audio information is to be provided by a source 14(n)(s) connected to the zone player 11(n), the audio information source interface 30 will selectively receive audio information from one of the audio information source(s) 14(n)(s) to which the zone player is connected and store the audio information in the audio information buffer 21. If the audio information from the selected audio information source 14(n)(s) is in analog form, the audio information source interface 30 will convert it to digital form. The selection oft he audio information source 14(n)(s) from which the audio information source interface 30 receives audio information is under control of the control module 42, which, in turn, receives control information from the user interface module through the user interface module interface 44. The audio information source interface 30 adds playback timing information to the digital audio information and buffers the combined audio and playback timing information in the audio information buffer 21. More specifically, as noted above, the audio information source interface 30 receives audio information from an audio information source 14(n)(s), converts it to digital form if necessary, and buffers it along with playback timing information in the audio information buffer 21. In addition, the audio information source interface 30 will also provide formatting and scheduling information for the digital audio information, whether as received from the selected audio information source 14(n)(s) or as converted from an analog audio information source. As will be made clear below, the formatting and scheduling information will control not only playback by the zone player 11(n) itself, but will also enable other zone players 11(n′), 11(n″), . . . that may be in a synchrony group for which the zone player 11(n) is the master device, to play the audio program associated with the audio information in synchrony with the zone player 11(n). In one particular embodiment, the audio information source interface 30 divides the audio information associated with an audio work into a series of frames, with each frame comprising digital audio information for a predetermined period of time. As used herein, an audio track may comprise any unit of audio information that is to be played without interruption. On the other hand, an audio program may comprise a series of one or more audio tracks that are to be played in succession. It will be appreciated that the tracks comprising the audio program may also be played without interruption, or alternatively playback between tracks may be interrupted by a selected time interval. FIG. 4 schematically depicts an illustrative framing strategy used in connection with one embodiment of the invention for a digital audio stream comprising an audio work. More specifically, FIG. 4 depicts a framed digital audio stream 50 comprising a sequence of frames 51 (1) through 51(F) (generally identified by reference numeral 51(f)). Each frame 51(f), in turn, comprises a series of audio samples 52(f)(1) through 52(f)(S) (generally identified by reference numeral 52(f)(s)) of the audio track. Preferably all of the frames will have the same number “S” of audio samples, although it will be appreciated from the following that is primarily for convenience. On the other hand, it will be appreciated that, the number of audio samples may differ from “S”; this may particularly be the case if the frame 51(f) contains the last audio samples for the digital audio stream for a particular audio work. In that case, the last frame 51(F) will preferably contain samples 52(F)(1) through 52(F)(x), where “x” is less than “S.” Generally, it is desirable that the number of samples be consistent among all frames 51(f), and in that case padding, which will not be played, can be added to the last frame 51(F). Associated with each frame 51(f) is a header 55(f) that includes a number of fields for storing other information that is useful in controlling playback of the audio samples in the respective frame 51(f). In particular, the header 55(f) associated with a frame 51(f) includes a frame sequence number field 56, an encoding type field 57, a sampling rate information field 58, a time stamp field 60, an end of track flag 61, and a length flag field 62. The header 55(f) may also include fields (not shown) for storing other information that is useful in controlling playback. Generally, the frame sequence number field 56 receives a sequence number “f” that identifies the relative position oft he frame 51(f) in the sequence of frames 51(1) . . . 51(f) . . . 51(F) containing the digital audio stream 50. The encoding type field 57 receives a value that identifies the type of encoding and/or compression that has been used in generating the digital audio stream. Conventional encoding or compression schemes include, for example, the well-known MP3 and WAV encoding and/or compression schemes, although it will be appreciated that other schemes may be provided for as well. The sampling rate information field 58 receives sampling rate information that indicates the sampling rate for the audio samples 52(f)(s). As will be apparent to those skilled in the art, the sampling rate determines the rate at which the zone player 11(n) is to play the audio samples 52(f)(s) in the frame, and, as will be described below, determines the period of the digital to analog converter clock 34. The condition of the end of work flag 61 indicates whether the frame 51(f) contains the last digital audio samples for the audio track associated with the framed digital audio work 50. If the frame 51(f) does not contain the audio samples that are associated with the end of the digital audio stream 50 for a respective audio work, the end of work flag will be clear. On the other hand, if the frame 51(f) does contain the audio samples that are associated with the end of the digital audio stream 50 for a respective audio work, the end of work flag 61 will be set. In addition, since the number of valid audio samples 52(F)(s) in the frame 51(F), that is, the samples that are not padding, may be less than “S,” the default number of audio samples in a frame 51(f), the length flag field 62 will contain a value that identifies the number of audio samples in 52(F)(s) in the last frame 51(F) of the audio work 50. If, as noted above, the frames have a consistent number “S” of samples, the samples 52(F)(x+1) through 52(F)(S) will contain padding, which will not be played. The time stamp field 60 stores a time stamp that identifies the time at which the zone player 11(n) is to play the respective frame. More specifically, for each frame of a framed digital audio stream 50 that is buffered in the audio information buffer 21, the audio information source interface 30, using timing information from the digital to analog converter clock 34, will determine a time at which the zone player 11(n) is to play the respective frame, and stores a time stamp identifying the playback time in the time stamp field 60. The time stamp associated with each frame will later be used by the playback scheduler 32 to determine when the portion of the digital audio stream stored in the frame is to be coupled to the digital to analog converter 33 to initiate play back. It will be appreciated that the time stamps that are associated with frames in sequential frames 51(1), 51(2), . . . , 51(F), will be such that they will be played back in order, and without an interruption between the sequential frames comprising the digital audio stream 50. It will further be appreciated that, after a time stamp has been determined for the first frame, stored in frame 51(1), of a digital audio stream 50, the audio information source interface 30 can determine time stamps for the subsequent frame 51(2), 51(3), . . . , 51(F) in relation to the number of samples “S” in the respective frames and the sample rate. The time stamps will also preferably be such that frames will be played back after some slight time delay after they have been buffered in the audio information buffer 21; the purpose for the time delay will be made clear below. Returning to FIG. 3, in addition to dividing the digital audio information into frames, the audio information source interface 30 also aggregates and/or divides the frames 51(f) as necessary into packets, each of which will be of a length that would fit into a message for transmission over the network, and associates each packet with a packet sequence number. For example, if a packet will accommodate multiple frames 51(f), 51(f+1), . . . 51(f+y−1), it will aggregate them into a packet and associate them with a packet number, for example p(x). If the entire frames 51(f) and 51(f+y−1) was accommodated in packet p(x), where “x” is the sequence number, which will occur if the size of a packet is an exact multiple of the frame size, the next packet, p(x+1) will begin with frame 51(f+y) and will include frames 51(f+y), . . . , 51(f+2y−1). Subsequent packets p(x+2), . . . will be formed in a similar manner. On the other hand, if the packet length will not accommodate an exact multiple of the frame size, the last frame in the packet will be continued at the beginning of the next packet. If the audio information source interface 30 is aware of track boundaries, which may be the case if the tracks are divided into files, the packets will reflect the track boundaries, that is, the packets will not contain frames from two tracks. Thus, if the last frames associated with a track are insufficient to fill a packet, the packet will contain padding from the last frame associated with the track to the end of the packet, and the next packet will begin with the first frames associated with the next track. In one embodiment, the audio information source interface 30 stores the packets in the audio information buffer 31 in a ring buffer. As is conventional, a ring buffer includes a series of storage locations in the buffer. Each entry will be sufficient to store one packet. Four pointers are used in connection with the ring buffer, a first pointer pointing to the beginning of the ring buffer, a second pointer pointing to the end oft he ring buffer, an third “write” pointer pointing to the entry into which a packet will be written and a fourth “read” pointer pointing to the entry from which packet will be read for use in playback. When a packet is read from the ring buffer for playback, it will be read from the entry pointed to by the read pointer. After the packet has been read, the read pointer will be advanced. If the read pointer points beyond the end of the ring buffer, as indicated by the end pointer, it will be reset to point to the entry pointed to by the beginning pointer, and the operations can be repeated. On the other hand, when the audio information source interface 30 stores a packet in the ring buffer, first determine whether the entry pointed to by the write pointer points to the same entry as the entry pointed to by the read pointer. If the write pointer points to the same entry as the entry pointed to by the read pointer, the entry contains at least a portion of a packet that has not yet been read for playback, and the audio information source interface 30 will delay storage oft he packet until the entire packet has been read and the read pointer advanced. After the read pointer has been advanced, the audio information source interface 30 can store the packet in the entry pointed to by the write pointer. After the packet has been stored, the audio information source interface 30 will advance the write pointer. If the write pointer points beyond the end of the ring buffer, as indicated by the end pointer, it will be reset to point to the entry pointed to by the beginning pointer, and the operations can be repeated. As noted above, the zone player 11(n) can operate both as an audio information channel device 23 and a member of the synchrony group 20 of which it is a member. In that case, the audio information buffer 31 can contain one ring buffer. On the other hand, the zone player 11(n) can operate as an audio information channel device 23 for one synchrony group 20(1) (FIG. 2A) and a member of another synchrony group 20(2). In that case, the audio information buffer 31 would maintain two ring buffers, one for the audio and timing information associated with synchrony group 20(1), and the other for the audio and timing information associated with synchrony group 20(2). It will be appreciated that, in the latter case, the zone player 11(n) will only use the audio and timing information that is associated with synchrony group 20(2) for playback. The playback scheduler 32 schedules playback of the audio information that is buffered in the audio information buffer 31 that is to be played by the zone player 11(n). Accordingly, under control of the playback scheduler 32, the digital audio information that is buffered in the audio information buffer 21 that is to be played by the zone player 11(n) is transferred to the digital to analog converter 33 for playback. As noted above, if the zone player 11(n) is operating as an audio information channel device 23 for a synchrony group 20 for which it is not a member, the playback scheduler 32 will not schedule the digital audio information that is to be played by that synchrony group 20 for playback. The playback scheduler 32 only schedules the digital audio information, if any, that is buffered in the audio information buffer 31 that is associated with a synchrony group for which the zone player 11(n) is a member, whether as master device 21 or a slave device 22(g). Essentially, the playback scheduler 32 makes use of the read pointer associated with the circular buffer that contains the audio and playback timing information that is to be played by the zone player 11(n). The playback scheduler 32 retrieves the packet information from the entry of the ring buffer pointed to by the read pointer, and then advances the ring pointer as described above. The playback scheduler 32 determines the boundaries of the frames in the packet and uses the time stamps in the time stamp fields 60 associated with the respective frame 51(f), along with timing information provided by the zone player 11(n)'s digital to analog converter clock 34, to determine when the respective frame is to be transferred to the digital to analog converter 33. Generally, when the time stamp associated with a buffered digital audio information frame corresponds to the current time as indicated by the digital to analog converter clock 34, the playback scheduler 32 will enable the respective frame to be transferred to the digital to analog converter 33. The digital to analog converter 33, also under control of the digital to analog converter clock 34, converts the buffered digital audio information to analog form, and provides the analog audio information to the audio amplifier 35 for amplification. The amplified analog information, in turn, is provided to the audio reproduction devices 15(n)(r) through the audio reproduction device interface 36. The audio reproduction devices 15(n)(r) transform the analog audio information signal to sound thereby to provide the audio program to a listener. The amount by which the audio amplifier 35 amplifies the analog signal is controlled by the control module 42, in response to volume control information provided by the user through the user interface module 13. The network communications manager 40 controls network communications over the network 12, and the network interface 41 transmits and receives message packets over the network 12. The network communications manager 40 generates and receives messages to facilitate the transfer of the various types of information described above in connection with FIG. 2, including the channel device control information, slave device control information, audio and playback timing information and the audio information channel device's clock timing information. In connection with the channel device control information and the slave device control information, the network communications manager 40 will generate messages for transfer over the network 12 in response to control information from the control module 42. Similarly, when the network communications manager 40 receives messages containing channel device control information and slave device control information, the network communications manager will provide the information to the control module 42 for processing. With regards to the audio information channel device's clock timing information, as noted above, the master device 21 and slave devices 22(g) of the synchrony group 20 obtain the clock timing information from the audio information channel device 23 using the well-known SNTP. If the zone player 11(n) is operating as the audio information channel device 23 for a synchrony group, during the SNTP operation, it will provide its current time, particularly a current time as indicated by its digital to analog converter clock 34. On the other hand, if the zone player 11(n) is operating as the master device 21 or slave device 22(g) of a synchrony group 20, it will receive the clock timing information from the audio information channel device 23. After the respective device 21, 22(g) has obtained the audio information channel device's clock timing information, it will generate a differential time value ΔT representing the difference between the time T indicated by its digital to analog converter clock 34 and the current time information from the audio information channel device 23. The differential time value will be used to update the time stamps for the frames of the digital audio stream 50 (FIG. 4) that are received from the audio information channel device. With regards to the audio and playback timing information, operations performed by the network communications manager 40 will depend on whether (i) the audio and playback timing information has been buffered in the audio information buffer 31 for transmission, as audio information channel device 23, over the network 12 to the master device 21 and/or slave devices 22(g) of a synchrony group, or (ii) the audio and playback timing information has been received from the network 12 to be played by the zone player 11(n) as either the master device 21 for a synchrony group or a slave device in a synchrony group. It will be appreciated that the network communications manager 40 may be engaged in both (i) and (ii) contemporaneously, since the zone player 11(n) may operate both as the audio information channel device 23(1) for a synchrony group 20(1) (reference FIG. 2A) of which it is not a member, and a member of another synchrony group 20(2) for which another zone player 11(n′) is the audio information channel device 23(2). With reference to item (i) above, after a packet that is to be transmitted has been buffered in the respective ring buffer, the network communications manager 40 retrieves the packet, packages it into a message and enables the network interface 41 to transmit the message over the network 12. If the control module 42 receives control information from the user interface module 13 (if the master device 21 is also the audio information channel device 23 for the synchrony group 20) or from the master device (if the master device 21 is not the audio information channel device 23 for the synchrony group 20) that would require the transmission of a “resynchronize” command as described above, the control module 42 of the audio information channel device 23 enables the network communications manager 40 to insert the command into a message containing the audio and playback timing information. Details oft he operations performed in connection with the “resynchronize” command will be described below. As noted above, the “resynchronize” command is used if the user enables a synchrony group to terminate the playback of a track that is currently being played, or cancel playback of a track whose playback has not begun. On the other hand, with reference to item (ii) above, if network interface 41 receives a message containing a packet containing frames of audio and playback timing information that the zone player 11(n) is to play either as a master device 21 or a slave device for a synchrony group 20, the network interface 41 provides the audio and playback timing information to the network communications manager 40. The network communications manager 40 will determine whether the packet contains a resynchronize command and, if so, notify the control module 42, which will enable operations to be performed as described below. In any case, the network communications manager 40 will normally buffer the various frames comprising the audio and playback timing information in the audio information buffer 31, and in that operation will generally operate as described above in connection with the audio information source interface 30. Before buffering them, however, the network communications manager 40 will update their time stamps using the time differential value described above. It will be appreciated that the network communications manager 40 will perform similar operations whether the messages that contain the packets were multi-cast messages or unicast messages as described above The updating of the time stamps by the master device 21 and the slave devices 22(g) in the synchrony group 20 will ensure that they all play the audio information synchronously. In particular, after the network communications manager 40 has received a frame 51(f) from the network interface 41, it will also obtain, from the digital to analog converter clock 34, the zone player 11(n)'s current time as indicated by its digital to analog converter clock 34. The network communications manager 40 will determine a time differential value that is the difference between the slave device's current clock time, as indicated by its digital to analog converter 34, and the audio information channel device's time as indicated by the audio information channel device's clock timing information. Accordingly, if the master or slave device's current time has a value TS and the audio information channel device's current time, as indicated by the clock timing information, has a value TC, the time differential value ΔT=TS−TC. If the current time of the master or slave device in the synchrony group 20, as indicated by its digital to analog converter clock 34, is ahead of the audio information channel device's clock time as indicated by the clock timing information received during the SNTP operation, the time differential value will have a positive value. On the other hand, if the master or slave device's current time is behind the audio information channel device's clock time, the time differential value ΔT will have a negative value. If the zone player 11(n) obtains clock timing information from the audio information channel device 23 periodically while it is a member of the synchrony group 20, the network communications manager 40 can generate an updated value for the time differential value ΔT when it receives the clock timing information from the audio information channel device 23, and will subsequently use the updated time differential value. The network communications manager 40 uses the time differential value ΔT that it generates from the audio information channel device timing information and zone player 11(n)'s current time to update the time stamps that will be associated with the digital audio information frames that the zone player 11(n) receives from the audio information channel device. For each digital audio information frame that is received from the audio information channel device, instead of storing the time stamp that is associated with the frame as received in the message in the audio information buffer 21, the network communications manager 40 will store the updated time stamp with the digital audio information frame. The updated time stamp is generated in a manner so that, when the zone player 11(n), as a member of the synchrony group plays back the digital audio information frame, it will do so in synchrony with other devices in the synchrony group. More specifically, after the zone player 11(n)'s network interface 41 receives a message containing a packet that, in turn, contains one or more frames 51(f), it will provide the packet to the network communications manager 40. For each frame 51(f) in the packet that the network communications manager 40 receives from the network interface 41, the network communications manager 40 will add the time differential value ΔT to the frame's time stamp, to generate the updated time stamp for the frame 51(f), and store the frame 51(f), along with the header 55(f) with the updated time stamp in the audio information buffer 31. Thus, for example, if a frame's time stamp has a time value TF, the network communications manager 40 will generate an updated time stamp TUF having a time value TUF=TF+ΔT. Since time value TUF according to the slave device's digital to analog converter clock 34 is simultaneous to the time value TF according to the audio information channel device's digital to analog converter clock 34, the zone player 11(n) device will play the digital audio information frame at the time determined by the audio information channel device 23. Since all of the members of the synchrony group 20 will perform the same operations, generating the updated time stamps TUF for the various frames 51(f) in relation to their respective differential time values, all of the zone players 11(n) in the synchrony group 20 will play them synchronously. The network communications manager 40 will generate updated time stamps TUF for all of the time stamps 60 in the packet, and then store the packet in the audio information buffer 31. It will be appreciated that, before storing a packet in the audio information buffer 21, the network communications manager 40 can compare the updated time stamps TUF associated with the frames in the packet to the slave device's current time as indicated by its digital to analog converter clock 34. If the network communications manager 40 determines the time indicated by the updated time stamps of frames 51(f) in the packet are earlier than the zone player's current time, it can discard the packet instead of storing it in the audio information buffer 21, since the zone player 11(n) will not play them. That is, if the updated time stamp has a time value TUF that identifies a time that is earlier than the zone player's current time Ts as indicated by the zone player's digital to analog converter clock 34, the network communications manager 40 can discard the packet. If the zone player 11(n) is operating as the master device 21 of a synchrony group 20, when the user, through the user interface module 13, notifies the zone player 11(n) that another zone player 11(n′) is to join the synchrony group 20 as a slave device 22(g), the control module 42 of the zone player 11(n) enables the network communications manager 40 to engage in an exchange of messages, described above in connection with FIG. 2, to enable the other zone player 11(n′) to join the synchrony group 20 as a slave device. As noted above, during the message exchange, the messages generated by the network communications manager 40 of the zone player 11(n) will provide the network communications manager oft he zone player 11(n′) that is to join the synchrony group 20 with information such as the multi-cast address being used by the audio information channel device 23 that is providing the audio program to the synchrony group 20, as well as a unicast network address for the audio information channel device 23. After receiving that information, the network communications manager and network interface of the zone player 11(n′) that is to join the synchrony group 20 can begin receiving the multi-cast messages containing the audio program for the synchrony group, engage in SNTP transactions with the audio information channel device 23 to obtain the latter's current time, and also enable the audio information channel device 23 to send the zone player 11(n′) frames 51(f) that it had previously broadcast using the unicast message transmission methodology as described above. On the other hand, if the network communications manager 40 and network interface 41 of the zone player 11(n) receive a message over the network 12 indicating that it is to become a slave device 22(g) of a synchrony group for which another zone player 11(n′) is the master device, the network communications manager 40 for zone player 11(n) will provide a notification to the control module 42 of zone player 11(n). Thereafter, the control module 42 of zone player 11(n) can enable the network communications manager 40 of zone player 11(n) to perform the operations described above to enable it to join the synchrony group 20. As noted above, the user, using user interface module 13, can enable the synchrony group to terminate playback of a track of an audio program that is currently being played. After playback of a track that is currently being played has been terminated, playback will continue in a conventional manner with the next track that has been buffered in the audio information buffer 31. It will be appreciated that could be the next track that is on the original play list, or a previous track. In addition, the user can enable the synchrony group 20 to cancel playback of a track that it has not yet begun to play, but for which buffering of packets has begun in the synchrony group 20. Both of these operations make use of the “resynchronize” command that the master device 21 of the synchrony group 20 can enable the audio information channel device 23 to include in the multi-cast message stream that it transmits to the synchrony group 20. Generally, in response to receipt of the resynchronize command, the members of the synchrony group 20 flush the ring buffer containing the packets that they are to play in the future. In addition, if the members of the synchrony group provide separate buffers for their respective digital to analog converters 33, the members will also flush those buffers as well. After the audio information channel device transmits a packet containing the resynchronize command: (i) in the case of the use of the resynchronize command to terminate playing of a track that is currently being played, the audio information channel device 23 will begin multi-casting packets for the next track, to begin play immediately, and will continue through the play list in the manner described above; and (ii) in the case of the use of the resynchronize command to cancel play of a track for which buffering has begun, but which is to be played in the future, the audio information channel device 23 will begin multi-casting packets for the track after the track that has been cancelled, to be played beginning at the time the cancelled track was to begin play, and will also continue through the play list in the manner described above. It will be appreciated that, (a) in the first case (item (i) directly above), the resynchronize command can enable the read pointer to be set to point to the entry in the circular buffer into which the first packet for the next track will be written, which will correspond to the entry to which the write pointer points, but (b) in the second case (item (ii) directly above), the resynchronize command can enable the write pointer for the circular buffer to be set to point to the entry that contains the first packet for the track whose play is being cancelled. It will further be appreciated that, if a track is cancelled for which buffering has not begun, the resynchronize command will generally not be necessary, since the audio information channel device 23 for the synchrony group 20 need only delete that track from the play list. Operations performed in connection with use of the resynchronize command to cancel playback of a track that is currently being played will be described in connection with Packet Sequence A below, and operations performed in connection with the use of the resynchronize command to cancel playback of a track that is has not yet begun to play, but for which buffering of packets has begun, will be described in connection with Packet Sequence B below. Packet Sequence A (A1.0) [packet 57] (A1.1 [continuation of frame 99] (A1.2) [frame 100, time=0:00:01, type=mp3 audio] (A1.3) [frame 101, time=0:00:02, type=mp3 audio] (A1.4) [frame 102, time=0:00:03, type=mp3 audio] (A2.0) [packet 58] (A2.1) [continuation of frame 102] (A2.2) [frame 103, time=0:00:04, type=mp3 audio] (A2.3) [frame 104, time=0:00:05, type=mp3 audio] (A2.4) [frame 105, time=0:00:06, type=mp3 audio] (A3.0) [packet 59] (A3.1) [continuation of frame 105] (A3.2) [frame 106, time=0:00:07, type=mp3 audio] (A3.3) [frame 107, time=0:00:08, type=mp3 audio] (A3.4) [frame 108, time=0:00:09, type=mp3 audio] (A4.0) [packet 60] (A4.1) [continuation of frame 108] (A4.2) [frame 109, time=0:00:10, type=mp3 audio] (A4.3) [Resynchronize command] (A4.4) [Padding, if necessary] (A5.0) [packet 61] (A5.1) [frame 1, time=0:00:07, type=mp3 audio] (A5.2) [frame 2, time=0:00:08, type=mp3 audio] (A5.3) [frame 3, time=0:00:09, type=mp3 audio] (A5.4) [frame 4, time=0.00:10, type=mp3 audio] (A6.0) [packet 62] (A6.1) [continuation of frame 4] (A6.2) [frame 5, time=0:00:11, type=mp3 audio] (A6.3) [frame 6, time=0:00:12, type=mp3 audio] (A6.4) [frame 7, time=0:00:13, type=mp3 audio] Packet Sequence A comprises a sequence of six packets, identified by packet 57 through packet 62, that the audio information channel device 23 multi-casts in respective messages to the members of a synchrony group 20. It will be appreciated that the series of messages that the audio information channel device 23 may multi-cast to the synchrony group 20 may include a messages prior to the packet 57, and may also include messages after packet 62. Each packet comprises a packet header, which is symbolized by lines (A1.0), (A2.0), . . . (A6.0) in Packet Sequence A, and will generally also include information associated with at least a portion of a frame. In the packets represented in Packet Sequence A, each packet includes information associated with a plurality of frames. Depending on the lengths of the packets, each packet may contain information associated with a portion of a frame, an entire frame, or multiple frames. In the illustration represented by Packet Sequence A, it is assumed that each packet may contain information associated with multiple frames. In addition, it is assumed that a packet does not necessarily contain information associated with an integral number of frames; in that case, a packet may contain information associated with a portion of a frame, and the next packet will contain the information associated with the rest of a frame. The frames and associated header playback timing information contained in the various packets are symbolized by lines (A1.1), (A1.2), . . . ,(A1.4), (A2.1), . . . (A6.4) of Packet Sequence A. Thus, for example, line (A1.2) of packet 57 represents the one-hundredth frame, that is, frame 51(100) (reference FIG. 4), oft he track whose audio information is being transmitted in the sequence of packets that includes packet 57. The frame 51(100) is to be played at an illustrative time, according to the audio information channel device's digital to analog converter clock, of “time=0:00:01,” and the frame is encoded and/or compressed using the well-known MP3 encoding and compression methodology. In that case, the legend “time=0:00:01” represents the time stamp that would be included in field 60 (FIG. 4) of the header associated with the frame 50(100) as multi-cast by the audio information channel device for the synchrony group. It will be appreciated that the playback time and encoding/compression methodology will be referred in the header 55(100) that is associated with the frame 51(100). It will also be appreciated that the header may also contain additional information as described above. Similarly, line (A1.3) of packet 57 represents the one-hundred and first frame, that is, frame 51(101), of the track whose audio information is being transmitted in the sequence of packets that includes packet 57. The frame 51(101) is to be played at an illustrative time, according to the audio information channel device's digital to analog converter clock, of “0:00:02,” and the frame is also encoded and/or compressed using the MP3 encoding and compression methodology. Line (A1.4) of packet 57 represents similar information, although it will be appreciated that, depending on the length of packet 57, the line may not represent the information for an entire frame 51(102) and/or its associated header. If the length of packet 57 is not sufficient to accommodate the information for the entire frame 51(102) and/or associated header, the information will continue in packet 58, as represented by line (A2.1) in Packet Sequence A. Similarly, if the length of packet 56 was not sufficient to contain the information for an entire frame 51(99) preceding frame 51(100), packet 57 (lines (A1.0) through 1.4) may contain any information from frame 51(99) that packet 56 was unable to accommodate. As noted above, when the master device 21 or a slave device 22(g) in the synchrony group 20 receives the packet 57, its respective network communications manager 40 will update the time stamps associated with the various frames 51(f) as described above before buffering the respective frames in the respective audio information buffer 31. Packets 58 and 59 contain information that is organized along the lines described above in connection with packet 57. Packet 60 also contains, as represented by lines (A4.1) and (A4.2), information that is organized along the lines of the information represented by lines (Ax.1) and (Ax.2) (“x” equals an integer) described above in connection with packets 57 through 59. On the other hand, packet 60 contains a resynchronize command, as represented by line (A4.3). Packet 60 also may contain padding, as represented by line 4.4, following the resynchronize command. As noted above, the master device 21 of a synchrony group 20 will enable the audio information channel device 23 that is providing audio information to the synchrony group 20 to multi-cast a message containing the resynchronize command when it receives notification from the user interface module 13 that the user wishes to cancel playback of a track that is currently being played. In the example depicted in Packet Sequence A, as will be described below, the audio information channel device 23 receives notification from the master device 21 that the user wishes to cancel playback of a track at a time corresponding to “time=0:00:07” according to its digital to analog converter clock 34, and, in line (A4.3) of packet 60 it will provide the resynchronize command, followed by padding, if necessary. As will be apparent from examining lines (A3.1) through (A3.4) of packet 59 and lines (A4.1) and (A4.2) of packet 60, although the audio information channel device 23 has received the notification from the synchrony group's master device 21 to multi-cast the resynchronize command at a time corresponding to “time=0:00:07” according to the clock time indicated by its digital to analog converter clock 34, it (that is, the audio information channel device 23) has already multi-cast messages containing frames that are to be played at that time and subsequently. That is, the audio information channel device 23 has, multi-cast in packet 59, frames 51(106) through 51(108) that contain time stamps “time=0:00:07,” “time=0:00:08” and “time=0:00:09,” respectively, and, in packet 60, in addition to the continuation of frame 51(108), frame 51(109) that contains time stamp “time=0:00:10.” (It will be appreciated that the times indicated by the illustrative time stamps are for illustration purposes only, and that in an actual embodiment the time stamps may have different values and differentials.) As noted above, the audio information channel device 23 multi-casts a message containing a packet that, in turn, contains the resynchronize command when it receives the notification from the master device 21 to do so. In the example depicted in Packet Sequence A, the packet will be multi-cast when the audio information channel device's digital to analog converter clock time corresponds to “0:00:07.” Subsequently, two things happen. In one, aspect, when the master device 21 and slave devices 22(g) receive the packet that contains the resynchronize command, they will stop playing the audio program that they are playing. In addition, the audio information channel device 23 will begin transmitting frames containing audio information for the next track, including therewith time stamps immediately following the digital to analog converter clock time at which the packet including the resynchronize command was transmitted. Accordingly, and with further reference to Packet Sequence A, the audio information channel device 23 will multi-cast a message containing packet 61. As indicated above, packet 61 contains, as represented in lines (A5.1) through (A5.3), frames 51(1) through 51(3), which are the first three frames of the next track of the audio program that is to be played. It is also compressed and encoded using the MP3 encoding and compression scheme, and it is accompanied by time stamps “time=0:00:07,” “time=0:00:08” and “time=0:00:10.” As noted above, the time stamp “time=0:00:07” corresponds to the clock time at which the audio information channel device 23 multi-casts the resynchronize command, and, when the master device 21 and slave devices 22(g) receive these frames, they would be expected to begin playing them very shortly, if not immediately after the audio information channel device 23 multi-casts the message containing the packet that, in turn, contains the resynchronize command. Packet 61 also includes at least a portion of the next frame, that is, frame 51(4), for that track. In addition, Packet Sequence A depicted above further includes a subsequent packet, namely, packet 62, that contains any necessary continuation of frame 51(4), as well as three subsequent frames. If any additional packets are required for the track, as well as for subsequent tracks, they can be multi-cast in a similar manner. As further noted above, the resynchronize command can also be used to cancel playing of one or more tracks for which playback has begun. This will be illustrated in connection with Packet Sequence B: Packet Sequence B (B1.0) [packet 157] (B1.1) [continuation of frame 99] (B1.2) [frame 100, time 32 0:00:01, type=mp3 audio] (B1.3) [frame 101, time=0:00:02, type=mp3 audio] (B1.4) [frame 102, time=0:00:03, type=mp3 audio] (B2.0) [packet 158] (B2.1) [continuation of frame 102] (B2.2) [frame 103, time=0:00:04, type=mp3 audio] (B2.3) [frame 104, time=0:00:05, type=mp3 audio] (B2.4) [frame 105, time=0:00:06, type=mp3 audio] (B3.0) [packet 159] (B3.1) [continuation of frame 105] (B3.2) [frame 106, time=0:00:07, type=mp3 audio] (B3.3) [track boundary notification] (B3.4) [Padding, if necessary] (B4.0) [packet 160] (B4.1) [frame 1, time=0:00:08, type=mp3 audio] (B4.2) [frame 2, time=0:00:09, type=mp3 audio] (B4.3) [frame 3, time=0:00:10, type=mp3 audio] (B5.0) [packet 161] (B5.1) [continuation of frame 3] (B5.2) [frame 4, time=0:00:11, type=mp3 audio] (B5.3) [Resynchronize, after packet 159] (B5.4) [Padding, if necessary] (B6.0) [packet 162] (B6.1) [frame 1, time=0:00:08, type=mp3 audio] (B6.2) [frame 2, time=0:00:09, type=mp3 audio] (B6.3) [frame 3, time=0:00:10, type=mp3 audio] (B6.4) [frame 4, time=0:00:11, type=mp3 audio] (B7.0) [packet 163] (B7.1) [continuation of frame 4] (B7.2) [frame 5, time=0:00:12, type=mp3 audio] (B7.3) [frame 6, time=0:00:13, type=mp3 audio] (B7.4) [frame 7, time=0:00:14, type=mp3 audio] Packet Sequence B comprises a series of seven packets, identified by packet 157 through 163 ,that the audio information channel device 23 multi-casts to the members of a synchrony group 20. As with Packet Sequence A, it will be appreciated that the series of packets that the audio information channel device 23 may multi-cast to the synchrony group 20 may include packets prior to the packet 157, and may also include packets after packet 162. Each packet comprises a packet header, which is symbolized by lines (B1.0), (B2.0), . . . (B7.0) in Packet Sequence B. As in Packet Sequence A, each packet will also generally include information associated with at least a portion of a frame 51(f)along with its associated frame 55(f). As in the packets represented in Packet Sequence A, each packet includes information associated with a plurality of frames. Depending on the lengths of the packets, each packet may contain information associated with a portion of a frame, an entire frame, or multiple frames. Further, as with Packet Sequence A, it is assumed that each packet may contain information associated with multiple frames. In addition, it is assumed that a packet does not necessarily contain information associated with an integral number of frames; in that case, a packet may contain information associated with a portion of a frame, and the next packet will contain the information associated with the rest of a frame. The structures oft he packets represented by Packet Sequence B are similar to those described above in connection with Packet Sequence A, and will not be repeated here. Generally, Packet Sequence B illustratively contains a sequence of packets that represent at least portions of three tracks that may have been selected from, for example, a play list. In particular, packets 157 through 159 represent frames from a portion of one track, packets 160 and 161 represent frames from a second track and packets 162 and 163 represent frames from a third track. The play list indicated that the first, second and third tracks were to be played in that order. With particular reference to Packet Sequence B, it should be noted that line (B3.3) indicates that packet 159 includes an indication that packet contains the last frame for the track, and line (B3.4) provides for padding to the end of the packet. The first frame of the next track begins in packet 160. In connection with the use of the resynchronize command to cancel playback of a track, at least a portion of which the audio information channel device 23 has multi-cast to the members of the synchrony group, packet 161, in line (B5.3) represents a resynchronize command that indicates that resynchronization is to occur after packet 159, that is, immediately after the packet that contains the last frame of the first of the three tracks represented by the packets in Packet Sequence B. It should be noted that the resynchronize command is in the packet 161, while the resynchronization is to occur at packet 160, that is, the synchrony group is to not play the track starting with packet 160, but instead is to begin playing the track frames for which begin with the next packet, that is, packet 162. As with Packet Sequence A, in Packet Sequence B the audio information channel device 23, in packet 162 and 163, multi-casts frames whose time stamps indicate that they are to be played when the frames that were multi-cast in packets 160 and 161 were to be played. By use of the resynchronize command and specifying a packet in this manner, the audio information channel device can cancel playback of a track for which playback has not yet begun. It will be appreciated that the resynchronize command is generally not necessary for cancelling play back of a track that the audio information channel device 23 has not started multi-casting to the synchrony group 20, since the audio information channel device 23 itself can re-order the play list to accommodate the cancellation. The invention provides a number of advantages. In particular, the invention provides a network audio system in which a number of devices share information can reproduce audio information synchronously, notwithstanding the fact that packets, which may contain digital audio information, transmitted over the network to the various zone players connected thereto may have differing delays and the zone players operate with independent clocks. Moreover, although the invention has been described in connection with audio information, it will be appreciated that the invention will find utility in connection with any type of isochronous information for which synchrony among devices is desired. The system is such that synchrony groups are created and destroyed dynamically, and in such a manner as to avoid requiring a dedicated device as the master device. It will be appreciated that a number of changes and modifications may be made to the network audio system 10 as described above. For example, although the invention has been described as providing that the audio information channel device 23 provides digital audio information to the members synchrony group 20 that has been encoded using particular types of encoding and compression methodologies, it will be appreciated that the audio information channel device 23 can provide digital audio information to various members of the synchrony group 20 that have been encoded and compressed using different types of encoding and compression methodologies, and, moreover, for which different sampling rates have been used. For example, the audio information channel device 23 may provide digital audio information to the master device 21 and slave devices 22(1) through 22(g1) using the MP3 methodology at a specified sampling rate, the digital audio information for the same program to slave devices 22(g1+1) through 22(g2) using the WAV methodology at one specified sampling rate, and to slave devices 22(g2+1) through 22(G) using the WAV methodology at another specified sampling rate. In that case, the audio information channel device 23 can specify the particular encoding and compression methodology that has been used in the encoding type field 57 associated with each frame and the sampling rate in the sampling rate field 58. Moreover, since the encoding and compression type and sampling rate are specified for each frame, the encoding and compression type and sampling rate can be changed from frame to frame. The audio information channel device 23 may use different multi-cast addresses for the different encoding and compression types and sampling rates, but it will be appreciated that would not be required. It will be appreciated that two advantages of providing that the encoding and compression methodology and the sampling rate is provided on a frame-by-frame basis, instead of on, for example, a track-by-track basis, is that would facilitate a slave device joining the synchrony group 20 at a frame mid-track, without requiring, for example, the master device 21 or the audio information channel device 23 to notify it of the encoding and compression methodology or the sampling rate. Another modification is that, instead of the network communications manager 40 of a member of a synchrony group 20 generating the updated time stamp TUF for a digital audio information frame by adding the time differential value ΔT to the time stamp TF associated with a frame, the network communications manager 40 may instead generate the updated time stamp TUF by subtracting the differential time value ΔT from the member's current time TS as indicated by the member's digital to analog converter clock 34 at the time at which the digital audio information is received. It will be appreciated, however, that there may be variable time delays in processing of messages by the slave device's network communications manager 40, and so it may be preferable to generate the time differential value ΔT using the time stamp TF provided by the audio information channel device 23. In addition, instead of the network communications manager 40 of a member of a synchrony group generating an updated time stamp to reflect the difference between the times indicated by the member's digital to analog converter clock and the audio information channel device's digital to analog converter clock, the network communications manager 40 can generate the time differential value ΔT and provide it to the member's playback scheduler 32. In that case, the member's network communications manager 40 can store each digital audio information frame along with the time stamp TF as received from the master device in the audio information buffer 21. The playback scheduler 32 can utilize the time differential value ΔT, and the time stamps TF associated with the digital audio information frames, to determine when the respective digital audio information frames are to be played. In determining when a digital audio information frame is to be played, the playback scheduler can add the time differential value to the time stamp TF associated with the digital audio frame, and enable the digital audio frame to be coupled to the digital to analog converter 33 when the time indicated by the sum corresponds to the current time as indicated by the slave device's digital to analog converter clock 34. Alternatively, when the member's digital to analog converter clock 34 updates its current time TS, the playback scheduler can generate an updated current time TS by subtracting the differential time value ΔT from the current time Ts, and using the updated current time TS to determine when to play a digital audio information frame. As described above, the members of a synchrony group 20 periodically obtain the audio information channel device's current time value and uses the current time value that it receives from the audio information channel device to periodically update the time differential value ΔT that it uses in updating the time stamps associated with the various frames. It will be appreciated that, if the digital to analog converter clock(s) associated with the member(s) of a synchrony group 20 are ensured to have the same rate as the digital to analog converter clock, a member need only obtain the current time value from the audio information channel device once, at the beginning of playback. As another alternative, if the zone players are provided with digital to analog converter clock 34 whose time and rate can be set by an element such as the network communications manager 40, when a zone player 11(n) is operating as a member of a synchrony group 20, its network communications manager 40 can use the various types of timing information that it receives from the audio information channel device 23, including the current time information and the playback timing information indicated by the time stamps that are associated with the various frames 51(f) comprising the audio and playback timing information that it receives, to adjust the synchrony group member's digital to analog converter clock's time value and/or the clock rate that it uses for playback. If the clock's time value is to be adjusted, when the synchrony group member's network communications manager 40 initially receives the current time information from the audio information channel device 23 for the synchrony group 20, the network communications manager 40 can set the synchrony group member's digital to analog converter clock 34 to the current time value as indicated by the audio information channel device's current time information. The network communications manager 40 can set the clock 34 to the current time value indicated by the audio information channel device's current time information once, or periodically as it receives the current time information. Alternatively or in addition, the synchrony group member's network communications manager 40 can use one or both of the current time information and/or the playback timing information in the time stamps associated with the respective frames 51(f) to adjust the clock rate of the clock 34 that it uses for playback. For example, when the synchrony group member's network communications manager 40 receives a frame 51(fx) having a time stamp having a time value Tfx, it can generate the updated time value TUfx=Tfx+ΔT as described above, and store the frame with the time stamp with the updated time value in the audio information buffer 30. In addition, since both the number of samples in a frame and the sampling rate, which determines the rate at which the frame is to be played, are known to the network communications manager 40, it can use that information, along with the updated time value TUFX that is to be used for frame 51(fX) to generate an expected updated time value TEfX+1 that is expected for the updated time stamp of the next frame 51(fX+1). After the synchrony group member's network communications manager 40 receives the next frame 51(fx+1), it can generate the updated time value TUfX+1 and compare that value to the expected updated time value TEfX+1. If the two time values do not correspond, or if the difference between them is above a selected threshold level, the clock that is used by the audio information channel device 23 to generate the time stamps is advancing at a different rate than the synchrony group member's digital to analog converter clock 34, and so the network communications manager 40 can adjust the rate of the digital to analog converter clock 34 to approach that of the clock used by the audio information channel device 23 so that the differential time value ΔT is constant. On the other hand, if the two time values do correspond, then the time differential value ΔT is constant, or the difference is below a threshold level, and the network communications manager 40 need not change the clock rate of the digital to analog converter clock 34. It will be appreciated that, if the clock rate is to be adjusted, the rate adjustment can be fixed, or it can vary based on, for example, the difference between the updated time value TUfX+1 and the expected updated time value TEfX+1. It will also be appreciated that, if no rate adjustment is performed for one frame 51(fx+1), the synchrony group member's network communications manager 40 can generate an expected updated time value TEfx+2 that is expected for the updated time stamp of the next frame 51(fx+2) using the updated time value TUFx determined for frame 51(fx), along with the number of samples in a frame and the sampling rate, and compare the expected updated time value TEfx+2 to the updated time value TUfx+2 that it generates when it receives frame 51(fx+2). At that point, if the network communications manager 41 determines that two time values do not correspond, or if the difference between them is above a selected threshold level, it can adjust the rate of the digital to analog converter clock 34. Similar operations can be performed if no rate adjustment is performed for several successive frames 51(fx+1), 51(fx+2), . . . This will accommodate the possibility that the rate differential between the clock 34 and the clock used by the audio information channel device 23 in generating the time stamps have rates that differ by an amount sufficiently small that it cannot be detected using time stamps of two or more successive frames. Instead or in addition to adjusting the clock rate as described above, the synchrony group member's network communications manager 40 can perform similar operations in connection with adjusting the clock rate in connection with the current time information that it receives from the audio information channel device 23. Furthermore, although the network audio system 10 has been described such that the master device 21 of a synchrony group 20 can, in response to control information provided thereto by a user through the user interface module 13, provide a notification to a zone player 11(n) that it is to become a member of its synchrony group 20 as a slave device 22(g), it will be appreciated that the user interface module 13 can provide the notification directly to the zone player 11(n) that is to become a member of the synchrony group 20. In that case, the zone player 11(n) can notify the master device 21 that it is to become a slave device 22(g) in the synchrony group 20, after which the master device 21 can provide information regarding the synchrony group 20, including the multi-cast and unicast addresses of the audio information channel device and other information as described above. Similarly, although the network audio system 10 has been described such that the master device 21 of a synchrony group 20 can, in response to control information provided thereto by a user through the user interface module 13, provide a command to a slave device 22(g) to enable the slave device 22(g) to adjust its volume, it will be appreciated that the user interface module 13 can provide control information directly to the slave device 22(g) to enable the slave device 22(g) to adjust its volume. In addition, although the network audio system 10 has been described such that each frames 51(f) is associated with a frame sequence number (reference field 56, FIG. 4), it will be appreciated that, if the packets described above in connection with Packet Sequence A and Packet Sequence B are provided with packet sequence numbers, the frame sequence numbers need not be provided, since the packet sequence numbers can suffice for defining the frame sequencing. Furthermore, although the network audio system 10 has been described such that the zone players 11(n) are provided with an audio amplifier 35 for amplifying the analog signal provided by the respective digital to analog converters 33, it will be appreciated that a zone player may be provided that does not itself include an audio amplifier. In that case, the analog signal may be coupled to an external amplifier for amplification as necessary before being provided to the audio reproduction device(s) 15(n)(r). It will be appreciated that a single zone player 11(n) may be provided with multiple audio amplifiers and audio reproduction device interfaces, and, if necessary, multiple digital to analog converters 33, to provide audio programs for corresponding numbers of synchrony groups. Similarly, although the zone players 11(n) have been described such that they may be connected to one or more audio information sources, it will be appreciated that an audio information source may form part of and be integrated into a zone player 11(n). For example, a zone player may include a compact disk player, cassette tape player, broadcast radio receiver, or the like, that has been integrated into it. In addition, as noted above, an individual zone player 11(n) may be connected to multiple audio information sources and may contemporaneously operate as the audio information channel device 23 for multiple synchrony groups. In addition, although FIG. 1 shows the network audio system 10 as including one user interface module 13, it will be appreciated that the system 10 may include a plurality of user interface modules. Each user interface module be useful for controlling all of the zone players as described above, or alternatively one or more of the user interface modules may be useful for controlling selected subsets of the zone players. Moreover, it will be appreciated that, although the invention has been described in connection with audio information, it will be appreciated that the invention will find utility in connection with any type of information for which synchrony among devices connected to a network is desired. As noted above, while a zone player 11(n) is operating as audio information channel device 23 for a synchrony group 20, when the zone player 11(n)'s audio information source interface 30 or network communications manager 40 stores digital audio information frames based on audio information from an audio information source 14(n)(s) in the audio information buffer 31, it will provide time stamps for the respective frames to schedule them for playback after some time delay after they have been buffered in the audio information buffer 31. The delay is provided so that, for other zone players 11(n′), 11(n″), . . . that are operating as members of a synchrony group, there will be sufficient time for the audio and playback timing information to be transferred over the network 12 to those other zone players 11(n′), 11(n″), . . . so that it can be processed and played by them at the appropriate time as described above. The time period that is selected for the time delay may be fixed or variable, and in either case may be based on a number of factors. If the time period selected for the time delay is fixed, it may be based on, for example, factors such as an estimate of the maximum latency in the network 12, the estimated maximum loading of the various components comprising the zone players 11(n), and other estimates as will be appreciated by those skilled in the art. The time delay may be the same for audio information from all types of audio information sources, and may be constant over the entire period that the synchrony group 20 is playing an audio work. Alternatively, different time delays may be utilized based on various criteria. For example, if the audio information is to be played independently of information associated with other types of media, the time delay may be selected to be relatively long, on the order of a significant fraction of a second, or longer. On the other hand, if the audio information is to be played contemporaneously with, for example, video information, which may be supplied by, for example, a video disk, video tape cassette, over cable, satellite, or broadcast television, which may not be buffered or which may be displayed independently of the network audio system 10, it may be undesirable to provide for such a lengthy delay, since the time delay oft he audio playback, in relation to the video display, may be noticeable. In that case, the zone player 11(n) may provide for a much shorter time delay. In one embodiment, the time delay provided for audio information to be played concurrently with video information is selected to be generally on the order of fifty milliseconds, which would barely, if at all, be perceptible to someone viewing the video. Other desirable time delays for information from other types of sources will be apparent to those skilled in the art. As yet a further possibility, the zone player 11(n), when operating as an audio information channel device 23 for a synchrony group 20, can dynamically determine the time delay based on a number of conditions in the network audio system 10, including, for example, the message transfer latency in network 12, the loading of microprocessors or other components that are used in the various zone players 11(n′), 11(n″), . . . that may comprise a synchrony group 20, as well as other factors. For example, if the audio information channel device 23 determines that the latency in the network 12 has increased beyond a selected threshold, the audio information channel device 23 can adjust the delay to increase the likelihood that the members of the synchrony group 20 will be able to receive the packets and process the frames so that they will be able to play them at the appropriate times. Similarly, if the audio information channel device 23 is notified that a member of the synchrony group 20 to which it provides audio information requires additional time to receive and process the frames that it transmits, the audio information channel device 23 can adjust the delay accordingly. It will be appreciated that, to reduce or minimize possible discontinuities in the audio playback by the members of the synchrony group, the audio information channel device 23 can, instead of adjusting the time delay during a particular audio track, adjust the time delay between tracks, during silent periods of a track or otherwise as will be appreciated by those skilled in the art. In addition, the audio information channel device 23 can use conventional audio compression methodologies to facilitate a speeding up and/or slowing down of playback of an audio track while it is in the process of providing additional time delay. Generally, the members of the synchrony group 20 can provide notifications to the audio information channel device 23 if they determine that they will need an additional time delay, and the audio information channel device 23 can adjust the time delay in accordance with the notifications from the members of the synchrony group 20. It will be appreciated that a system in accordance with the invention can be constructed in whole or in part from special purpose hardware or a general purpose computer system, or any combination thereof, any portion of which may be controlled by a suitable program. Any program may in whole or in part comprise part of or be stored on the system in a conventional manner, or it may in whole or in part be provided in to the system over a network or other mechanism for transferring information in a conventional manner. In addition, it will be appreciated that the system may be operated and/or otherwise controlled by means of information provided by an operator using operator input elements (not shown) which may be connected directly to the system or which may transfer the information to the system over a network or other mechanism for transferring information in a conventional manner. The foregoing description has been limited to a specific embodiment of this invention. It will be apparent, however, that various variations and modifications may be made to the invention, with the attainment of some or all of the advantages of the invention. It is the object of the appended claims to cover these and such other variations and modifications as come within the true spirit and scope of the invention. What is claimed as new and desired to be secured by Letters Patent of the United States is: | <SOH> BACKGROUND OF THE INVENTION <EOH>There are a number of circumstances under which it is desirable to maintain synchrony of operations among a plurality of independently-clocked digital data processing devices in relation to, for example, information that is provided thereto by a common source. For example, systems are being developed in which one audio information source can distribute audio information in digital form to a number of audio playback devices for playback. The audio playback devices receive the digital information and convert it to analog form for playback. The audio playback devices may be located in the same room or they may be distributed in different rooms in a residence such as a house or an apartment, in different offices in an office building, or the like. For example, in a system installed in a residence, one audio playback device may be located in a living room, while another audio playback device is be located in a kitchen, and yet other audio playback devices may be located in various bedrooms of a house. In such an arrangement, the audio information that is distributed to various audio playback devices may relate to the same audio program, or the information may relate to different audio programs. If the audio information source provides audio information relating to the same audio program to two or more audio playback devices at the same time, the audio playback devices will generally contemporaneously play the same program. For example, if the audio information source provides audio information to audio playback devices located in the living room and kitchen in a house at the same time, they will generally contemporaneously play the same program. One problem that can arise is to ensure that, if two or more audio playback devices are contemporaneously attempting to play back the same audio program, they do so simultaneously. Small differences in the audio playback devices' start times and/or playback speeds can be perceived by a listener as an echo effect, and larger differences can be very annoying. Differences can arise because for a number of reasons, including delays in the transfer of audio information over the network. Such delays can differ as among the various audio playback devices for a variety of reasons, including where they are connected into the network, message traffic and other reasons as will be apparent to those skilled in the art. Another problem arises from the following. When an audio playback device converts the digital audio information from digital to analog form, it does so using a clock that provides timing information. Generally, the audio playback devices that are being developed have independent clocks, and, if they are not clocking at precisely the same rate, the audio playback provided by the various devices can get out of synchronization. | <SOH> SUMMARY OF THE INVENTION <EOH>The invention provides a new and improved system and method for synchronizing operations among a number of digital data processing devices that are regulated by independent clocking devices. Generally, the invention will find utility in connection with any type of information for which synchrony among devices connected to a network is desired. The invention is described in connection with a plurality of audio playback devices that receive digital audio information that is to be played back in synchrony, but it will be appreciated that the invention can find usefulness in connection with any kind of information for which coordination among devices that have independent clocking devices would find utility. In brief summary, the invention provides, in one aspect, a system for maintaining synchrony of operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that distributes tasks to a synchrony group comprising a plurality of devices that are to perform the tasks distributed by the task distribution device in synchrony. The task distribution device distributes each task to the members oft he synchrony group over a network. Each task is associated with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task. Each member oft he synchrony group periodically obtains from the task distribution device an indication oft he current time indicated by its clock, determines a time differential between the task distribution device's clock and its respective clock and determines therefrom a time at which, according to its respective clock, the time stamp indicates that it is to execute the task. In one embodiment, the tasks that are distributed include audio information for an audio track that is to be played by all of the devices comprising the synchrony group synchronously. The audio track is divided into a series of frames, each of which is associated with a time stamp indicating the time, relative to the clock maintained by an audio information channel device, which, in that embodiment, serves as the task distribution device, at which the members of the synchrony group are to play the respective frame. Each member of the synchrony group, using a very accurate protocol, periodically obtains the time indicated by the audio information channel device, and determines a differential between the time as indicated by its local clock and the audio information channel device's clock. The member uses the differential and the time as indicated by the time stamp to determine the time, relative to its local clock, at which it is to play the respective frame. The members of the synchrony group do this for all of the frames, and accordingly are able to play the frames in synchrony. | 20040401 | 20120731 | 20070215 | 64951.0 | G06F946 | 0 | NICKERSON, JEFFREY L | SYSTEM AND METHOD FOR SYNCHRONIZING OPERATIONS AMONG A PLURALITY OF INDEPENDENTLY CLOCKED DIGITAL DATA PROCESSING DEVICES | UNDISCOUNTED | 0 | ACCEPTED | G06F | 2,004 |
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10,816,264 | ACCEPTED | Semiconductor substrate with interconnections and embedded circuit elements | A semiconductor substrate integrated with interconnections and circuit components. A silicon backplane is processed with silicon processing to provide electrical connectivity for circuit elements. In one embodiment functional circuit elements, e.g., MEMS, switches, filters, are integrated on the silicon backplane. In one embodiment the function circuit elements are monolithically processed into the silicon backplane. In one embodiment the silicon backplane includes interconnections for integrated circuits on different substrates to be bonded to the silicon backplane. | 1. An interconnect apparatus comprising: a silicon substrate; contact pads processed on the silicon substrate to connect to an integrated circuit (IC) die; interconnections selectively interconnecting the contact pads, the interconnections processed on the silicon substrate; and circuit elements processed on the silicon substrate with the same processing as the contact pads and the interconnections to interoperate with the IC die. 2. An interconnect apparatus according to claim 1, wherein the circuit elements comprise a micro electromechanical system (MEMS) device. 3. An interconnect apparatus according to claim 2, wherein the MEMS device further includes a microfluidic system. 4. An interconnect apparatus according to claim 2, wherein the MEMS device further includes an actuation circuit device. 5. An interconnect apparatus according to claim 1, wherein the circuit elements comprise a sensor circuit. 6. An interconnect apparatus according to claim 1, wherein the silicon substrate comprises a high-resistivity silicon substrate. 7. An interconnect apparatus according to claim 6, wherein the circuit elements comprise optical circuit components. 8. An interconnect apparatus according to claim 1, wherein the circuit elements comprise an active circuit element. 9. An interconnect apparatus according to claim 1, further comprising a cap processed onto the silicon substrate to hermetically isolate circuit elements on the silicon substrate. 10. An interconnect apparatus according to claim 9, wherein the cap comprises a cap of silicon-based material. 11. An interconnect apparatus according to claim 9, further comprising interconnect vias manufactured in the cap to provide electrical connectivity to contact pads on the silicon substrate. 12. A method comprising: integrating interconnections and passive circuit elements into a silicon backplane with processing steps of a first precision level; and integrating on the interconnections of the silicon backplane an integrated circuit (IC) produced on a separate silicon substrate with a second precision level of processing, the IC to interconnect with the passive circuit elements, the second precision level being more precise than the first precision level. 13. A method according to claim 12, wherein integrating interconnections and passive elements into the silicon backplane comprises integrating into high-resistivity silicon. 14. A method according to claim 12, further comprising integrating a micro electro-mechanical system (MEMS) device into the silicon backplane with the processing steps of the first precision level. 15. A method according to claim 14, wherein the MEMS device further comprises a film bulk acoustic resonator (FBAR) device. 16. A method according to claim 12, wherein integrating on the interconnections of the silicon backplane the IC comprises flip-chip bonding the IC to the silicon backplane. 17. A method according to claim 12, further comprising integrating multiple ICs on the silicon backplane, each of the ICs being silicon-based ICs. 18. A method according to claim 17, wherein integrating the ICs on the silicon backplane comprises creating an all silicon-based radio front-end module IC. 19. An integrated circuit chip having a circuit element on a substrate created with a first lithographic processing interconnected on a high-resistivity silicon interconnect substrate having functional circuit elements embedded in the interconnect substrate, created by the process of: processing contact pads and electrical traces on the silicon substrate with a second lithographic processing to interconnect the circuit elements; processing the circuit elements on the interconnection substrate with the second lithographic processing; and interconnecting the circuit element of the first lithographic processing on the separate substrate to contact pads on the interconnection substrate. 20. An integrated circuit chip according to claim 19, wherein the silicon interconnect substrate further includes a micro electromechanical system (MEMS) device. 21. An integrated circuit chip according to claim 19, wherein the circuit elements comprise an active circuit element. 22. An integrated circuit chip according to claim 19, wherein the circuit elements on separate substrates comprise circuit elements all on silicon substrates. 23. An integrated circuit chip according to claim 19, wherein the silicon interconnect substrate further comprises a silicon lid to hermetically seal functional circuit elements. 24. An integrated circuit chip according to claim 23, wherein the lid further comprises interconnections through the lid to interconnection contact pads on the silicon interconnect substrate. 25. A method for utilizing a semiconductor processing equipment comprising: integrating electrical connectivity elements monolithically on a silicon backplane with the processing equipment, at least some of the connectivity elements to receive an integrated circuit (IC) chip, a technology to be used to manufacture the IC chip to produce a smaller minimum feature size than the technology of the processing equipment; and integrating monolithically on the silicon backplane circuit with the processing equipment elements including micro electromechanical systems (MEMS) and passive components to interoperate with the IC chip to process a signal to be received by the resulting circuit. 26. A method according to claim 25, wherein integrating electrical connectivity elements on the silicon backplane includes integrating MEMS devices to bond a flip-chip mounted IC to the backplane. 27. A method according to claim 25, wherein integrating the electrical connectivity elements and the circuit elements comprises integrating the elements on the silicon backplane with processing equipment having lithographic technology to produce a 0.5 μm or larger feature size. 28. A method according to claim 25, wherein integrating the electrical connectivity elements and the circuit elements comprises integrating the elements to prepare the silicon backplane to produce a system on a chip integrated circuit. 29. An electronic system comprising: a chip with an integrated circuit (IC) bonded to contact pads on a silicon interconnect backplane, the silicon backplane having integrated circuits including a micro electromechanical system (MEMS) device processed into the silicon backplane with the same processing used to create the contact pads, the processing different from a processing used to create the IC; and a direct current power storage cell coupled with the chip to supply power to the chip. 30. A system according to claim 29, wherein the MEMS device further includes a microfluidic system. 31. A system according to claim 29, wherein the MEMS device further includes an actuation circuit device. 32. A system according to claim 29, wherein the circuit elements comprise sensor circuits. 33. A system according to claim 29, further comprising a cap processed onto the silicon backplane to hermetically isolate circuit elements on the silicon backplane. 34. A system according to claim 33, wherein the cap comprises a cap of silicon-based material. 35. A system according to claim 33, further comprising interconnections manufactured through the cap to provide electrical connectivity to contact pads on the silicon backplane. | FIELD Embodiments of the invention relate to silicon integrated circuits, and particularly to interconnecting integrated circuits with other circuit elements. BACKGROUND Many circuits currently use discrete components and/or integrated circuits (ICs) that may be produced with different types of processing and materials. Some of the different types of processing and materials may include complimentary-metal-oxide-semiconductor (CMOS), gallium-arsenide (GaAs), lithium tantalate (LiTaO3), and silicon-germanium (SiGe). Traditionally many of these devices have been assembled and interconnected on ceramic or organic interconnect devices that have traces to interconnect the various ICs and/or passives. The resulting interconnected circuit is then packaged as a single component. FIG. 1 is a known example of interconnecting various ICs with an interconnect device. Passive substrate 110 represents traditional interconnect devices, typically organic material (e.g., FR4) or ceramics. Passive substrate 110 is passive because it has no circuit functionality except to assemble and interconnect the various circuit components. All circuit functionality, such as processing, manipulating, affecting, etc., signals in the circuit is performed in the various circuit elements assembled on top of passive substrate 110. Thus, the ICs, switches, and passives shown in FIG. 1 are the functional circuit elements. The main advantage to using passive substrate 110 is that it is relatively inexpensive, generally only requiring that contact pads and interconnect traces be manufactured onto passive substrate 110. The circuit components are then bonded or soldered to passive substrate 110. Thus, various ICs of potentially many disparate processing technologies and/or procedures can all be packaged as a single component. Examples of various circuit elements include RLC 120, which represents discrete passive components such as resistors, inductors, and capacitors, and filters created with such passive components. These components are used to passively process signals occurring in system 100. ICs of differing processing technologies and materials are also shown as CMOS 130, SiGe 140, LiTaO3 150, and switch 160. CMOS 130 represents ICs that are made with complimentary metal (or other conductor) oxide semiconductor (e.g., silicon) processing. SiGe 140 represents ICs that are manufactured with silicon germanium processing. Because of the differences in processing of these two technologies, processing of circuits using these different technologies occurs on different substrates and interconnecting occurs on an interconnect device such as passive substrate 110. The use of different types of circuits made with the different technologies is assumed to be well understood in the art, and consequently will not be discussed herein. Note that the interconnecting of ICs 130, 140, 150, and 160 may be performed by flip-chipping the IC and bonding to bumps, or by the use of wire bonds, as shown with SiGe 140. Additionally, the various ICs shown could be bare die rather than packaged. LiTaO3 150 represents devices processed on a lithium tantalite substrate, which is a boutique processing technology that is traditionally used with surface acoustic wave (SAW) filters. Switch 160 is shown as one traditional element that is processed using GaAs to provide fast switching, for example, switches in radio frequency (RF) devices. Input/Outputs 170 are used in packaging system 100. Input/Outputs 170 pads or bumps use vias through passive substrate 110 to provide interconnection to the circuitry of system 100 to the packaging of system 100. The interconnection to the packaging may be through wire bonding or metal traces connecting to the packaging pins. Despite the inexpensive interconnect provided by passive substrate 110, there may be undesired expenses in the processing of the various ICs shown in FIG. 1. For example, many ICs use boutique processing technologies such at LiTaO3 or GaAs that can be significantly more costly than silicon-based processing. However, use of these processes has been necessary to achieve the desired performance. Integrating these components made with boutique processes with strictly silicon-based components has proven costly. Another example of the expense in traditional practice is that many circuits require the use of resistors, capacitors, inductors, and passive filters. These components may be integrated directly on the IC, or they may be discrete components, such as LTCC (low temperature co-fired ceramic) devices, that require bonding to passive substrate 110. However, there are costs associated with using discrete passive components, as well as directly integrating passives on modern ICs manufactured with high precision (e.g., 90 nm) processing. The higher precision processing is used to scale ICs with active devices such as transistors, which are typically scaleable. The increased cost of manufacturing may be justified by the increases in performance of the resulting devices. However, higher precision processing does little or nothing to increase performance of components such as the passives that do not scale. Also, for devices such as voltage regulation circuits and certain sensors, non-high-end processing is also perfectly viable for producing circuit elements of acceptable performance, making the use of high-end processing for such devices wasteful. Thus, integrating these devices on ICs consisting of scaleable active device with modern processing techniques is wasteful of processing costs as well as valuable die real estate. BRIEF DESCRIPTION OF THE DRAWINGS The description of embodiments of the invention includes various illustrations by way of example, and not by way of limitation in the figures and accompanying drawings, in which like reference numerals refer to similar elements. FIG. 1 is a known example of interconnecting various ICs with an interconnect device. FIG. 2 is a block diagram of a silicon substrate interconnecting integrated electrical circuit components and interconnections in accordance with one embodiment of the invention. FIG. 3 is a block diagram of interconnecting ICs with a silicon backplane having components processed on the silicon backplane in accordance with one embodiment of the invention. FIG. 4 is a block diagram of externally interconnecting a capped integrated circuit in accordance with one embodiment of the invention. FIG. 5 is a block diagram of circuit elements on a silicon interconnect backplane in accordance with one embodiment of the invention. DETAILED DESCRIPTION Methods and apparatuses are described for using a silicon backplane to integrate and interconnect electronic components (e.g., passive, switch, filter, analog transistor, power transistor, etc.) that cannot be built on highly scalable very large scale integration (VLSI) processes in a cost effective manner. With a silicon backplane device, functional circuit elements may be monolithically integrated on the interconnect device with the interconnections. In one embodiment a silicon backplane has components and interconnects embedded in the substrate with contacts to interconnect to other ICs. In one embodiment all components integrated directly into the silicon of a silicon backplane are manufactured with monolithic processing. Monolithic is to be understood as being part of, or consistent with, the single crystalline structure of the silicon backplane. Monolithic may be understood as processing where the resulting integrated components/interconnects are part of the silicon wafer. Another way to understand monolithic is that the devices integrated with monolithic processing are embedded in the silicon substrate (in the wafer). This may be, for example, in contrast to modern VLSI CMOS processes that have many layers, such as interconnect layers on top of integrated devices. Thus, monolithic may or may not be understood as including polysilicon grown off the silicon crystal of the silicon substrate. This would generally not include devices in a silicon substrate whose processing results in a device with layers (e.g., CMOS). Monolithic is meant to include the use of conductors, such as traces and contact pads. It may also include some active devices, for example, transistors, as discussed below. FIG. 2 is a block diagram of a silicon substrate interconnecting integrated electrical circuit components and interconnections in accordance with one embodiment of the invention. Semiconductor substrate 210 includes a semiconductor substrate in which circuit components may be integrated or embedded, with semiconductor processing. The use of silicon as a semiconductor substrate is common. Semiconductor substrate 210 includes external interconnection 220, internal interconnection 230, passive 240, and contacts 250. External interconnection 220 includes traces, wells, etc., used by system 200 to interconnect to packaging (e.g., pins, leads), other substrates, etc. For example, system 200 may be interconnected with power supply 270 to provide power to the circuits. Power supply 270 may be from a regulated voltage source, battery (a power storage cell), etc. Power supply 270 is typically a direct current (DC) power source. Internal interconnections 230 selectively interconnect the components embedded in semiconductor substrate 210 with each other and/or with ICs 260, which represents one or more integrated circuits that may be connected (e.g., wire bonded, flip-chip bonded) to semiconductor substrate 210. In one embodiment passive 240 represents passive component(s) monolithically embedded in semiconductor substrate 210 with the same processing used to produce interconnections 220 and/or 230. Passive 240 provides electrical functionality in the circuit of system 200. Thus, passive 240 may modify, filter, or otherwise process signals of system 200. Contacts 250 represents contact (bonding) pads used to interconnect ICs 260 to internal interconnections 230, which in turn interconnects ICs 260 to other elements of system 200. Contacts 250 may be areas of metal and/or high conductive material used to provide an area of relatively larger size to connect, e.g., wire bonds, bumps, to the interconnection lines/traces of internal interconnections 230. In one embodiment system 200 is enclosed with an enclosing device 280. The enclosing device will be discussed in more detail below. FIG. 3 is a block diagram of interconnecting ICs with a silicon backplane having components processed on the silicon backplane in accordance with one embodiment of the invention. Silicon backplane 310 is a piece of silicon that may be processed according to silicon processing techniques. Silicon backplane 310 is processed to interconnect various circuit elements in a single system on an IC. System 300 may include various ICs, including CMOS 350, SiGe 360, and CMOS 370. These devices represent any type of IC that may be integrated into system 300 with other ICs in the same packaging. In one embodiment the components of system 300 include silicon-based devices, thus avoiding the expense of boutique processing technologies such as LiTaO3 and GaAs. However, non silicon-based IC devices may also be included in system 300 through integration onto silicon backplane 310. These devices may be electrically attached to contact pads on silicon backplane 310 by bumps or wire bonding. These devices will be selectively interconnected to each other, and to external contact pads according to the design of the system of which they are a part. The footprint of interconnect lines or traces and contact (bonding) pads, bumps, etc. do not require high precision lithographic processing technology because they generally derive no benefit from scaling. Additionally, note that certain common circuit elements, such as passive components (e.g., resistors, capacitors) do not scale, and may not require a high precision lithographic processing technology to be produced. Thus, all such aspects of a silicon interconnect device may be integrated into the silicon interconnect with the use of non high-end (e.g., 1 μm, 0.5 μm minimum feature size) processing techniques. Note that for certain signaling requirements, traces of a larger size may in fact be desirable for an interconnect device. On such devices, the precision level of high end, state-of-the-art lithography (e.g., feature size of 90 nm, 65 nm) is not needed; a lower precision processing technology may be sufficient. Additionally, the interconnects and passives can be embedded together in a silicon substrate with many fewer processing steps that the numerous steps generally used in high end processing to produce multiple layers of circuit material (e.g., interconnects) on top of the structures actually embedded in the original substrate. Because silicon backplane 310 includes a semiconductor substrate, in one embodiment it can be processed to have integrated devices, making silicon backplane 310 more than simply a passive interconnect device. Although it provides interconnection for system 300, silicon backplane 310 is also processed with components that provide electrical circuit functionality to system 300. For example, silicon backplane 310 may include switch 320, RLC passives 330, and bulk acoustic wave (BAW) filter 340. More or fewer components may be included in silicon backplane 310. Note that as the interconnection aspects of silicon backplane 310 may be processed on silicon backplane 310 using non state-of-the-art lithographic processing, the functional elements processed on silicon backplane 310 may also be processed with such lesser-precision lithographic processing technologies. One advantage gained by using the same processing steps is the reduced cost in integrating the functional elements and interconnections with the same processing steps. Although the lithographic (x-y dimensions) technologies involved may be of lesser than state-of-the-art, processing in the vertical direction (z dimension; e.g., thin film deposition, film thickness control) may be state-of-the-art. In one embodiment higher precision processing may be performed on part or all of the material of silicon backplane 310 to manufacture the integrated circuit elements. Note that the cost of a silicon substrate used as an interconnect device is initially of higher cost than a corresponding organic or ceramic interconnect substrate. The materials of traditional interconnect substrates are cheaper than silicon, and the processing to produce the interconnection is more expensive in silicon, even when using lower-end lithographic precision processing techniques. However, the cost of a silicon substrate interconnect becomes justifiable when functional circuit elements may be manufactured in the silicon backplane, removing some or all of the need for discrete passive components. Cost reduction may also be achieved by having a substrate in which to process silicon-based components as replacements for some ICs produced with boutique processing. By eliminating the need to place some or all high real-estate passives on ICs manufactured with high-end processing technologies, or use discrete passive components that must be integrated onto a system, along with replacing ICs produced with expensive boutique technologies, the overall system costs may actually be lower. With these other costs reduced, the additional cost of the silicon backplane over the passive substrates is more than offset by the savings. For example, one of the savings potentially achieved by the use of silicon backplane includes the fact that the level of lithographic precision for the embedded devices may be accomplished on equipment that may not be state-of-the-art. Thus, previous generation equipment could be used to produce circuit elements that may otherwise be less efficiently produced on high-end equipment that may be better used to produce highly scalable circuit elements. The production of a system on a single chip may be effectively accomplished by using non state-of-the-art lithographic equipment to produce silicon backplane 310 with its embedded circuit elements and interconnections, and interconnect scalable ICs produced with state-of-the-art equipment. In one embodiment switch 320 includes a micro electromechanical (MEMS) switch processed on silicon backplane 310 using non high-end lithographic processing. Low insertion loss MEMS switching is known for switching, e.g., between channels of an RF module. RLC passives 330 include discrete elements as well as RLC passive filters for processing input signals. BAW 340 is a film bulk acoustic resonator, which is a silicon-based equivalent of a SAW filter used as an alternative to LiTaO3 SAW filters. SAW filters cannot be monolithically integrated into silicon because they are made with LiTaO3; therefore, these and other components built with boutique processing technologies will remain discrete components, instead of being able to be integrated on silicon backplane 310. The use of silicon backplane 310 allows for the design of system 300 with state-of-the-art processing technologies to produce ICs that have scaleable circuit components, while allowing offloading of some circuit functions to functional circuit components integrated into silicon backplane 310 that may not have such exacting requirements for manufacturing. Because MEMS devices are generally hermetically sealed, in an embodiment where MEMS device(s) are used, system 300 is capped with lid 380. Lid 380 may be, for example, a silicon, or silicon-based structure that can be affixed to the material of silicon backplane 310. FIG. 4 is a block diagram of externally interconnecting a capped integrated circuit in accordance with one embodiment of the invention. System 400 is similar to that discussed above in FIG. 3. In one embodiment silicon substrate 410 includes MEMS 430 and passive 440 integrated directly on silicon substrate 410. MEMS 430 and passive 440 are merely examples of functional circuit elements that may be embedded on silicon substrate 410, and are not meant to be restrictive or exclusive of circuit elements that may be embedded in silicon substrate 410. System 400 also includes exemplary ICs 460 and 470. IC 460 is shown bonded with bumps, and IC 470 is shown bonded with wire bonds. It is to be understood that more or fewer ICs may be included in system 400, and the various ICs may be bonded with bumps, wire bond, or other methods. Interconnections 450 represent the selective internal connections among the devices of system 400. For example, IC 460 may be interconnected to MEMS 430, while IC 470 may not be, etc. Interconnections 450 may also include traces/lines to interconnect IC 460 to IC 470. In one embodiment it will be advantageous for system 400 to have cap 480 over the circuitry. System 400, once integrated with all of its components, is packaged as an IC in accordance with embodiments of the invention. An IC will typically have electrical connectivity points such as pins/leads on inline or quad packages, or balls on a ball-grid array (BGA) package. To connect system 400 to its packaging, system 400 is provided with external interconnection mechanism(s). Through these interconnections system 400 is able to interface with other ICs, other circuitry, power supplies, etc. In one embodiment silicon substrate 410 is processed with external interconnection 420. If system 400 includes cap 480, external interconnection 420 may extend from the internal region of system 400 that is capped to outside the cap. External interconnection 420 is then bonded to the intended packaging of system 400 via, e.g., wire bonds 421. The use of wire bonds to connect an integrated circuit to its packaging is known. In one embodiment system 400 includes cap 480, and vias 422 drilled or etched through cap 480 to external interconnection 420. External interconnection 420 is manufactured directly on silicon substrate 410 to provide external connectivity, as with the other interconnection techniques described above. Vias 422 may be, e.g., insulated and then filled or coated with metal and/or have a wire bond used to connect to interconnection 450. It is again to be understood that the interconnections described here may be used alone or in combination, and the description herein is not intended to be limiting regarding a manner to interconnect system 400 to an external connection point. In one embodiment system 400 is manufactured with silicon vias 490 through silicon substrate 410 to contact pads for the external interconnections. Vias 490 are typically drilled or etched through substrate 410, insulated, and filled or coated with metal to provide electrical connectivity between the contact pads and, for example, conductive traces to the pins, pads, or balls of the packaging. FIG. 5 is a block diagram of circuit elements on a silicon interconnect backplane in accordance with one embodiment of the invention. The elements of FIG. 5 are not intended to be shown to scale. In one embodiment the elements on silicon backplane 510 are part of a highly integrated radio module. Silicon backplane 510 includes high voltage chip (HVC) 520 and radio frequency IC (RFIC) 530. HVC 520 represents an integrated circuit (whether separate IC(s) or embedded in silicon backplane 510) that provides the high voltage necessary to actuate some MEMS devices. In a radio module, RFIC 530 may refer to multiple separate components of the radio module, as with a multimode radio module. Power amplifier (PA) 590 represents a final stage of an RF transmitter that drives an antenna attached to the circuit on silicon backplane 510, in the embodiment where silicon backplane 510 includes an RF module. PA 590 may be an IC bonded to silicon backplane 510. PAs are generally GaAs or SiGe devices and typically require passive matching and tuning networks for maximum efficiency and radiation by the antenna. These matching networks can be processed in silicon backplane 510 while one or more die encompassing PA 590 are connected to silicon backplane 510 with flip chip or wire bonding. HVC 520, RFIC 530, and PA 590 are typically integrated circuits that will be integrated together in a radio module on an interconnect device. These ICs may be integrated on silicon backplane 510 with either wire bond or flip chip bonding. These elements are meant only for purposes of illustration, and other ICs, including ICs unrelated to a radio module, may be included. In one embodiment these ICs represent any kind of IC desirable for a system on a chip design. In one embodiment silicon backplane 510 includes several components integrated directly on silicon backplane 510 through silicon processing. For purposes of illustration, and not by way of limitation, silicon backplane 510 may include balun 540, BAW 550, passives 560, and MEMS switch 570. Balun 540 represents the many components that make up the circuitry to transform an incoming single-ended radio signal to a differential signal. Because the separate elements of balun 540 are typically components that do not scale, they can be manufactured with the lower-end processing with which silicon backplane 510 is manufactured. This provides good reason to integrate them directly onto silicon backplane 510 rather than as discrete components, or integrated on other ICs. BAW 550 represents multiple SAW filters made of MEMS in the silicon of silicon backplane 510. In one embodiment BAW 550 is a film bulk acoustic resonator (FBAR) filter. BAW 550 represents what may be multiple discrete BAWs in the system. As with the BAW components, another component that can be processed directly into the silicon of silicon backplane 510 is passives 560. Passives 560 represents discrete resistors, capacitors, and inductors that may be present in an integrated circuit system, as well as LC filters that are typically present in radio modules. In one embodiment the silicon of silicon backplane 510 is high resistivity silicon. Thus, the passives may be manufactured of low-impedance conductor on high-resistivity silicon, which provides better performance in passives 560. The proper manufacturing of the components will result in high-Q passives 560 integrated directly into the silicon of silicon backplane 510. As part of a radio module, or as part of another system integrated on a single die, silicon backplane 510 may include other circuit components, including, but not limited to: MEMS 581, voltage regulation 582, and optical 583. MEMS 581 is intended to represent a broad range of MEMS devices that may be integrated on an IC. For example, MEMS 481 may include: microfluidic devices with fluid channels, fluid storage (radiators), recombiners, microchannel cooler, and pumps; actuation devices used to trigger events due to force, inclining of a device in which the system is found, etc.; and electrical and/or biological sensor circuits. Voltage regulation 582 includes regulation circuits to filter noise out of a voltage supply, or convert one voltage to another. Additionally, voltage regulation 582 may include circuits that regulate a non-steady voltage supply into a regulated voltage level. In one embodiment silicon backplane 510 also includes optical devices 583. This includes, but is not limited to, fiber alignment channels, laser components, etc. In one embodiment silicon backplane is made of high-resistivity silicon, which looks like glass to infrared optical signals. Thus, the use of high-resistivity silicon may be advantageous when optical devices 583 are included in silicon backplane 510. In each of optical 583 and voltage regulation 482, note that these circuits may lend themselves to have active devices, such transistors, diodes, etc. Although active devices may typically be scaleable, in various circuits, such as embodiments of the circuits mentioned here, active components may be manufactured with non high-end processing technologies because of the nature of the components needed. For example, voltage regulation will typically require larger transistors that can be adequately manufactured for the purposes they serve in their respective circuits with less precise lithography. Thus, even with what may be considered to be scaleable components may be integrated on silicon backplane 510. In one embodiment such active components may be monolithically processed with the interconnections and other circuit elements integrated on silicon backplane 510. Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of phrases such as “in one embodiment,” or “in another embodiment” describe various embodiments of the invention, and are not necessarily all referring to the same embodiment. Besides the embodiments described herein, it will be appreciated that various modifications may be made to embodiments of the invention without departing from their scope. Therefore, the illustrations and examples herein should be construed in an illustrative, and not a restrictive sense. The scope of the invention should be measured solely by reference to the claims that follow. | <SOH> BACKGROUND <EOH>Many circuits currently use discrete components and/or integrated circuits (ICs) that may be produced with different types of processing and materials. Some of the different types of processing and materials may include complimentary-metal-oxide-semiconductor (CMOS), gallium-arsenide (GaAs), lithium tantalate (LiTaO 3 ), and silicon-germanium (SiGe). Traditionally many of these devices have been assembled and interconnected on ceramic or organic interconnect devices that have traces to interconnect the various ICs and/or passives. The resulting interconnected circuit is then packaged as a single component. FIG. 1 is a known example of interconnecting various ICs with an interconnect device. Passive substrate 110 represents traditional interconnect devices, typically organic material (e.g., FR 4 ) or ceramics. Passive substrate 110 is passive because it has no circuit functionality except to assemble and interconnect the various circuit components. All circuit functionality, such as processing, manipulating, affecting, etc., signals in the circuit is performed in the various circuit elements assembled on top of passive substrate 110 . Thus, the ICs, switches, and passives shown in FIG. 1 are the functional circuit elements. The main advantage to using passive substrate 110 is that it is relatively inexpensive, generally only requiring that contact pads and interconnect traces be manufactured onto passive substrate 110 . The circuit components are then bonded or soldered to passive substrate 110 . Thus, various ICs of potentially many disparate processing technologies and/or procedures can all be packaged as a single component. Examples of various circuit elements include RLC 120 , which represents discrete passive components such as resistors, inductors, and capacitors, and filters created with such passive components. These components are used to passively process signals occurring in system 100 . ICs of differing processing technologies and materials are also shown as CMOS 130 , SiGe 140 , LiTaO 3 150 , and switch 160 . CMOS 130 represents ICs that are made with complimentary metal (or other conductor) oxide semiconductor (e.g., silicon) processing. SiGe 140 represents ICs that are manufactured with silicon germanium processing. Because of the differences in processing of these two technologies, processing of circuits using these different technologies occurs on different substrates and interconnecting occurs on an interconnect device such as passive substrate 110 . The use of different types of circuits made with the different technologies is assumed to be well understood in the art, and consequently will not be discussed herein. Note that the interconnecting of ICs 130 , 140 , 150 , and 160 may be performed by flip-chipping the IC and bonding to bumps, or by the use of wire bonds, as shown with SiGe 140 . Additionally, the various ICs shown could be bare die rather than packaged. LiTaO 3 150 represents devices processed on a lithium tantalite substrate, which is a boutique processing technology that is traditionally used with surface acoustic wave (SAW) filters. Switch 160 is shown as one traditional element that is processed using GaAs to provide fast switching, for example, switches in radio frequency (RF) devices. Input/Outputs 170 are used in packaging system 100 . Input/Outputs 170 pads or bumps use vias through passive substrate 110 to provide interconnection to the circuitry of system 100 to the packaging of system 100 . The interconnection to the packaging may be through wire bonding or metal traces connecting to the packaging pins. Despite the inexpensive interconnect provided by passive substrate 110 , there may be undesired expenses in the processing of the various ICs shown in FIG. 1 . For example, many ICs use boutique processing technologies such at LiTaO 3 or GaAs that can be significantly more costly than silicon-based processing. However, use of these processes has been necessary to achieve the desired performance. Integrating these components made with boutique processes with strictly silicon-based components has proven costly. Another example of the expense in traditional practice is that many circuits require the use of resistors, capacitors, inductors, and passive filters. These components may be integrated directly on the IC, or they may be discrete components, such as LTCC (low temperature co-fired ceramic) devices, that require bonding to passive substrate 110 . However, there are costs associated with using discrete passive components, as well as directly integrating passives on modern ICs manufactured with high precision (e.g., 90 nm) processing. The higher precision processing is used to scale ICs with active devices such as transistors, which are typically scaleable. The increased cost of manufacturing may be justified by the increases in performance of the resulting devices. However, higher precision processing does little or nothing to increase performance of components such as the passives that do not scale. Also, for devices such as voltage regulation circuits and certain sensors, non-high-end processing is also perfectly viable for producing circuit elements of acceptable performance, making the use of high-end processing for such devices wasteful. Thus, integrating these devices on ICs consisting of scaleable active device with modern processing techniques is wasteful of processing costs as well as valuable die real estate. | <SOH> BRIEF DESCRIPTION OF THE DRAWINGS <EOH>The description of embodiments of the invention includes various illustrations by way of example, and not by way of limitation in the figures and accompanying drawings, in which like reference numerals refer to similar elements. FIG. 1 is a known example of interconnecting various ICs with an interconnect device. FIG. 2 is a block diagram of a silicon substrate interconnecting integrated electrical circuit components and interconnections in accordance with one embodiment of the invention. FIG. 3 is a block diagram of interconnecting ICs with a silicon backplane having components processed on the silicon backplane in accordance with one embodiment of the invention. FIG. 4 is a block diagram of externally interconnecting a capped integrated circuit in accordance with one embodiment of the invention. FIG. 5 is a block diagram of circuit elements on a silicon interconnect backplane in accordance with one embodiment of the invention. detailed-description description="Detailed Description" end="lead"? | 20040331 | 20071225 | 20051006 | 79459.0 | 0 | MANDALA, VICTOR A | SEMICONDUCTOR SUBSTRATE WITH INTERCONNECTIONS AND EMBEDDED CIRCUIT ELEMENTS | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,632 | ACCEPTED | Foldable bicycle frame with axial rear wheel removal | A rear wheel is axially removable from a bicycle frame after a support arm is pivoted away from an initial position overlying the rear wheel. A bicycle drive mechanism is not removed together with the rear wheel, but instead, is left mounted on another support arm. Both support arms straddle the rear wheel during bicycle use and are pivotable to fold the bicycle for compact storage. | 1. A frame for a bicycle having front and rear wheels, comprising: a) a main frame support on which the front wheel is mounted; and b) a pair of frame support arms mounted on the main frame support and straddling the rear wheel to support the rear wheel in a use position for rotation about a rear wheel axis during bicycle motion, at least one of the frame support arms extending over the rear wheel to the rear wheel axis during bicycle motion and being pivoted to a remote position away from the rear wheel axis to enable removal of the rear wheel in a direction axially of the rear wheel axis when the bicycle is not in motion. 2. The frame of claim 1, wherein said at least one frame support arm is pivotably mounted on the main frame support about a pivot axis parallel to the rear wheel axis. 3. The frame of claim 2, and a drive mounted on the main frame support, the drive including a pair of foot pedals rotatable about the pivot axis to rotate the rear wheel. 4. The frame of claim 2, wherein the main frame support includes an elongated seat support, and wherein said at least one frame support arm is mounted at two locations lengthwise spaced apart along the seat support. 5. The frame of claim 1, wherein each frame support arm has a generally triangular configuration. 6. The frame of claim 1, wherein the frame support arms are independently pivotably mounted on the main frame support. 7. The frame of claim 1, wherein both frame support arms are simultaneously pivotably movable to position the rear wheel closer to the front wheel for compact storage when the bicycle is not in motion. 8. (canceled) 9. The frame of claim 1, and a drive including a drive mechanism mounted on the other of the frame support arms, the drive mechanism remaining on the other of the frame support arms after the axial removal of the rear wheel. 10. The frame of claim 9, wherein the drive mechanism includes a gear changer, and wherein the drive includes a front pedal assembly rotatable about a pedal axis, and a chain connected between the front pedal assembly and the gear changer. 11. The frame of claim 9, wherein the drive mechanism includes a braking assembly. 12. The frame of claim 9, wherein the drive mechanism includes an axle extending between the frame support arms, a casing surrounding the axle, and a hub connected to a rim of the rear wheel. 13. The frame of claim 1, and a handlebar assembly operatively connected to the front wheel and mounted for turning movement on the main frame support to steer the front wheel. 14. The frame of claim 1, wherein said at least one frame support arm is mounted on the main frame support with a quick release fastener. 15. (canceled) 16. A bicycle, comprising: a) front and rear wheels; b) a main frame support on which the front wheel is mounted; and c) a pair of frame support arms mounted on the main frame support and straddling the rear wheel to support the rear wheel in a use position for rotation about a rear wheel axis during bicycle motion, at least one of the frame support arms extending over the rear wheel to the rear wheel axis during bicycle motion and being pivoted to a remote position away from the rear wheel axis to enable removal of the rear wheel in a direction axially of the rear wheel axis when the bicycle is not in motion. 17. The bicycle of claim 16, wherein the rear wheel is replaceable and identical with the front wheel. 18. A frame for a bicycle having front and rear wheels, comprising: a) a main frame support on which the front wheel is mounted; and b) a frame support arm mounted on the main frame support and overlying the rear wheel to support the rear wheel in a use position for rotation about a rear wheel axis during bicycle motion, the rear wheel being axially removably mounted on the frame support arm to enable axial removal of the rear wheel away from the use position when the bicycle is not in motion. 19. The frame of claim 18, and a drive including a drive mechanism mounted on the frame support arm, the drive mechanism remaining on the frame support arm after the axial removal of the rear wheel. | BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to bicycles and, more particularly, to bicycle frames which are foldable to occupy less storage space, and which enable quick and easy removal of rear bicycle wheels for replacement or repair. 2. Description of the Related Art Folding bicycles, whether driven by foot pedaling and/or whether assisted by a motor drive, are well known to conserve storage space when the bicycles are not being ridden. Although generally satisfactory for their intended purpose, the known bicycles are foldable about an axis other than the pedal axis and, hence, occupy more storage space than necessary. Another problem with bicycles, whether foldable or not, is wheel maintenance, especially the rear wheel on which a drive mechanism is conventionally mounted. It is often laborious to change a flat rear wheel tire due to the presence of the drive mechanism which conventionally includes a gear changer and a braking assembly. SUMMARY OF THE INVENTION Objects of the Invention One object of this invention is to enable rapid removal of, and easy access to, a rear wheel of a bicycle to effect repairs or replacement. Another object of this invention is to enable removal of the rear wheel without also removing the drive mechanism. Still another object ofthis invention is to fold the bicycle for minimum storage space about the pedal axis. Yet another object of this invention is to enable the front and rear wheels to be identical for easier replacement and maintenance. Features of the Invention In keeping with these objects and others which will become apparent hereinafter, one feature of this invention resides, briefly stated, in a frame for a bicycle in which a front wheel is mounted on a main frame support, and a rear wheel is mounted by at least one frame support arm, or by a pair of frame support arms, on the main frame support. The arms straddle and support the rear wheel in a use position for rotation about a rear wheel axis during bicycle motion. In accordance with one aspect of this invention, at least one of the arms is movable to enable movement of the rear wheel away from the use position when the bicycle is not in motion. Preferably, the movable arm is pivotably mounted on the main frame support about a pivot axis parallel to the rear wheel axis. In the preferred embodiment, the pivot axis is coincident with a pedal axis about which a foot pedal drive assembly is rotated when the bicycle is in motion. Upon pivoting the movable arm out of its initial straddling position at one side of the rear wheel, the rear wheel is removed in a direction axially of the rear wheel axis in a manner not unlike the axial removal of an automobile tire from an automobile. This axial removal has heretofore not been achieved for bicycle wheel maintenance. Another aspect of this invention relates to the mounting of a bicycle drive mechanism on the other of the arms. The drive mechanism typically includes a gear changer and a brake assembly, and these components are conventionally mounted on the rear wheel for joint movement therewith, thereby complicating rear wheel maintenance. In accordance with this invention, the drive mechanism is not jointly mounted on the rear wheel, and hence, the rear wheel can be removed from the bicycle while leaving the drive mechanism in place on the other arm. Each arm may be independently pivotably mounted on the main frame support, and both arms may be simultaneously pivotable to reposition the rear wheel from its initial use position in which the rear wheel is directly behind the front wheel, to a folded-up position in which the rear wheel is elevated relative to the front wheel to achieve compact storage. By pivoting both arms about the foot pedal axis, a particularly compact storage space is obtained. The novel features which are considered as characteristic ofthe invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a bicycle having a frame in accordance with this invention; FIG. 2 is a broken-away, enlarged, sectional view taken on line 2-2 of FIG. 1; FIG. 3 is a broken-away view taken on line 3-3 of FIG. 1; FIG. 4 is a sectional view taken on line 4-4 of FIG. 1; FIG. 5 is a view similar to FIG. 4, but during rear wheel movement; FIG. 6 is a view of the rear of the bicycle of FIG. 1 during rear wheel movement; FIG. 7 is a sectional view taken on line 7-7 of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a bicycle 10 includes a frame 12, a front wheel 14, a rear wheel 16, handlebars 18, a seat 20, and a foot pedal assembly 22. The frame includes a main frame support 24 and a pair of frame support arms 26, 28 mounted on the main support 24 and straddling the rear wheel 16, as best seen in FIG. 2. The main support 24 includes a front tube 30 through which a steering post 40 is inserted. The handlebars 18 are mounted at one end of the post 40, and the opposite end of the post 40 is connected to a hub 42 of the front wheel. The post 40 is mounted for rotation in the front tube 30 and, hence, steering is achieved by turning the handlebars 18. The main support 24 also includes a rear tube 32 through which a seat post 38 is inserted. The seat 20 is mounted at an upper end of the post 38 and is slid lengthwise thereof until a desired seat height is achieved. The main support 24 further includes upper tube 34 extending between upper regions of the front 30 and rear 32 tubes, and a lower tube 36 extending between lower regions of the front 30 and rear 32 tubes. In some bicycles, the upper tube 24 can be eliminated. As best seen in FIG. 3, the front pedal assembly 22 includes a pair of foot pedals 44, 46 mounted on crank arms 48, 50 to turn a pedal gear 52 about a pedal axis 54. A gear changer 60 comprised of multiple gears is, as described below, operatively connected with the rear wheel 16. An endless drive chain 58 is trained about the pedal gear 52 and a selected gear 62 of the gear changer 60. A rider rotatably pushing the foot pedals about the pedal axis 54 causes the rear wheel 16 to rotate about a rear wheel axis 64 through the chain 58 at a rate determined by the gear ratio between the pedal gear 52 and the selected gear 62. As previously mentioned, the support arms 26, 28 are mounted on the main frame support 24 and extend rearwardly thereof in straddling relation to the rear wheel 16. The support arms 26, 28 mount the rear wheel on the bicycle frame for rotation about the rear wheel axis 64 during use when the bicycle is in motion. As described below, by movement of at least one of the support arms, the rear wheel is removable from the bicycle frame for repair or replacement. Also, by movement of both support arms, the bicycle is folded up for compact storage. As shown in FIG. 1, each support arm 26, 28 is generally shaped as an isosceles triangle having three bars 66, 68, 70 bounding an open triangular space 72 to reduce weight. Each comer between bars 66, 68 is pivotably connected for movement about the pedal axis 54 at a lower region of the rear tube 32. Each comer between bars 66, 70 is connected to the rear wheel 16 at rear wheel axis 64. Each corner between bars 68, 70 is connected to the rear tube 32 at an upper region above the pivotable connection at the pedal axis 54. As shown in FIG. 3, the rear wheel 16 includes a tire 80 mounted on a rim 78 having a central hub 74 which is connected by a plurality of fasteners 76 to a circular flange 82 of a tubular housing 84 extending along the rear wheel axis 64. An axle 86 extends through the housing 84 and is connected at its opposite axial ends to the support arms 26, 28. Bearings 88, 90 assist in journaling the axle 86. The gear changer 60 is exteriorly mounted on the housing 84. A disk brake 92 is likewise exteriorly mounted on the housing 84. As described so far, the brake 92, changer 60, housing 84, bearings 88, 90, together with the illustrated nuts and washers, constitute a drive mechanism. A quick-release fastener 94, as best seen in FIGS. 4-5, is employed to detachably connect the arm 26 to the axle 86. Another quick-release fastener 96, as best seen in FIG. 2, is employed to detachably connect the arm 26 to the rear tube 32. Upon release by the fasteners 94, 96, the arm 26 is free to be pivoted in the counterclockwise direction depicted by arrow A in FIG. 6 about the pedal axis 54 until the arm 26 no longer overlaps the rear wheel. Thereupon, the fasteners 76 are removed to release the rear wheel from the drive mechanism. The rear wheel can now be axially removed from the axle 86 along the axis 64, as depicted in FIG. 7. The drive mechanism remains in place and is not removed together with the rear wheel. The rear wheel can now be repaired and/or replaced. Mounting the repaired or a new rear wheel is achieved by reversing the above procedure. The rear wheel is axially returned to the axle 86, the fasteners 76 reconnect the hub 74 to the flange 82, the arm 26 is pivoted clockwise opposite to the arrow A, and the fasteners 94, 96 are reengaged. In order to stow the bicycle in a folded configuration, both arms 26, 28 are pivoted about the pedal axis 54 in the direction of arrow A, as shown by dashed lines in FIG. 1. Before this is done, however, the fasteners 96 on both sides of the rear tube 32 are operated to release the arms 26, 28. As the arms are pivoted, the rear wheel 16 jointly moves with them. Thus, the bicycle has been folded from its initial state in which the front and rear wheels are aligned, one directly behind the other, to a folded state in which the rear wheel is elevated and closer to the front wheel. It will be understood that each of the elements described above, or two or more together, also may find a useful application in other types of constructions differing from the types described above. For example, each support arm need not be directly connected to the main frame support at the rear tube 32. Each support arm could be connected through a suspension to the main frame support. The suspension could be a shock absorber connected to another location on the main frame support, for example, the lower tube 36. The invention herein need not be limited to the use of two support arms as described above, and could also be implemented as a single support arm 28 on which the drive mechanism is mounted. In other words, in some applications, the support arm 26 can be eliminated. The single support arm 28 need not be movable and, in some cases, may be rigid with the frame. The rear wheel is axially removable from the single support arm 28 whether movable or rigid. Another advantageous feature of this invention resides in the feature that the front wheel and the rear wheel can be identical, and that a single spare can be used to replace either the front or rear wheels. In a conventional bicycle, the front and rear wheels are different and cannot be interchanged. While the invention has been illustrated and described as embodied in a foldable bicycle frame with axial rear wheel removal, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention The present invention generally relates to bicycles and, more particularly, to bicycle frames which are foldable to occupy less storage space, and which enable quick and easy removal of rear bicycle wheels for replacement or repair. 2. Description of the Related Art Folding bicycles, whether driven by foot pedaling and/or whether assisted by a motor drive, are well known to conserve storage space when the bicycles are not being ridden. Although generally satisfactory for their intended purpose, the known bicycles are foldable about an axis other than the pedal axis and, hence, occupy more storage space than necessary. Another problem with bicycles, whether foldable or not, is wheel maintenance, especially the rear wheel on which a drive mechanism is conventionally mounted. It is often laborious to change a flat rear wheel tire due to the presence of the drive mechanism which conventionally includes a gear changer and a braking assembly. | <SOH> SUMMARY OF THE INVENTION <EOH> | 20040402 | 20051227 | 20051006 | 60265.0 | 0 | LUBY, MATTHEW D | FOLDABLE BICYCLE FRAME WITH AXIAL REAR WHEEL REMOVAL | SMALL | 0 | ACCEPTED | 2,004 |
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10,816,654 | ACCEPTED | Front suspension tuning apparatus for vehicle with struts | The present invention provides a suspension tuning device for vehicles with struts. More specifically the suspension tuning device generally comprises an upper plate, two lower plates and a strut mounting plate. The plates are constructed to mount juxtaposed to a standard strut tower mounting member to permit quick front suspension alterations throughout an increased range when compared to the prior art. | 1. In a front vehicle suspension, wherein said suspension includes a left and a right strut, each said strut including a top end, a bottom end and a longitudinal centerline, said longitudinal centerline defining a strut axis, a left and a right structural strut tower, said left and said right strut towers each including a mounting member oriented in a plane substantially orthogonal with said respective left and said right strut axes, said mounting members each including three elongated camber slots, said camber slots on parallel axes and spaced about said strut axes, said mounting members having atop surface and a bottom surface, wherein said upper end of said left strut attaches to said left strut tower mounting member via said camber slots, wherein said upper end of said right strut attaches to said right strut tower mounting member via said camber slots, wherein said camber slots are oriented to allow an upper portion of said strut axes to be tilted toward the center of said vehicle, a suspension tuning kit comprising: an upper plate, said upper plate having a top surface and a bottom surface, said upper plate having four substantially parallel secondary camber slots, wherein three of said secondary camber slots are constructed and arranged to align with said mounting member camber slots, wherein one of said secondary camber slots is longer than the other three secondary camber slots, wherein said longer secondary camber slot aligns with a drilled aperture, wherein said drilled aperture is located in said mounting member of said strut tower, said upper plate including at least two caster slots, said at least two caster slots arranged to have substantially parallel and transverse axes to said secondary camber slots and spaced about said strut axis, said bottom surface, including a contoured cavity, said contoured cavity constructed and arranged for slidably locating a strut mounting plate, said bottom surface positionable parallel and juxtaposed to said top surface of said strut tower mounting member; a strut mounting plate, said strut mounting plate including a lower plate portion, said lower plate portion including a bottom surface and a top surface, said top surface including an upwardly extending boss, said upwardly extending boss including a bore therethrough for mounting said top end of a strut member, said lower plate portion including at least two threaded apertures, said at least two threaded apertures arranged to align with said at least two caster slots, said strut mounting plate slidably mounted within said upper plate cavity, said bottom surface mounted juxtaposed to said mounting member top surface; a first lower plate, said first lower plate including three apertures therethrough, said three apertures constructed and arranged to align with said camber slots, said first lower plate positioned parallel and juxtaposed to said bottom surface of said mounting member; a second lower plate, said second lower plate including at least one aperture therethrough, wherein said at least one aperture is constructed and arranged to cooperate with said drilled aperture, said second lower plate positioned parallel and juxtaposed to said bottom surface of said mounting member; wherein said kit may be secured to said left or said right strut tower, wherein at least four threaded fasteners extend through said lower plates, said mounting member and said upper plate, said threaded fasteners cooperating with at least four threaded nuts, wherein said threaded fasteners cooperate with said nuts to secure said suspension tuning kit to said strut tower mounting member, wherein wheel caster and camber is infinitely adjustable throughout an extended range. 2. The suspension tuning kit as set forth in claim 1 wherein said first lower plate is substantially L-shaped, said L-shaped first lower plate including a top surface and a bottom surface. 3. The suspension tuning kit as set forth in claim 2 wherein at least three of said four threaded fasteners are weldably secured to said bottom surface of said first lower plate, said at least three threaded fasteners extending upward and substantially perpendicular to said top surface. 4. The suspension tuning kit as set forth in claim 2 wherein said first lower plate is constructed from metal. 5. The suspension tuning kit as set forth in claim 1 wherein said second lower plate is substantially rectangular in shape, said second lower plate including a top surface and a bottom surface, wherein at least one of said four threaded fasteners is weldably secured to said bottom surface of said second lower plate, said at least one threaded fastener extending upward and substantially perpendicular to said top surface. 6. The suspension tuning kit as set forth in claim 5 wherein said second lower plate includes a means for preventing rotation of said second lower plate with respect to said strut tower mounting member. 7. The suspension tuning kit as set forth in claim 6 wherein said means for preventing rotation includes a threaded aperture, wherein said threaded aperture is constructed and arranged to cooperate with a second drilled aperture located in said mounting member of said strut tower, wherein a threaded fastener extends downward through said mounting member and threadably engages said threaded aperture, whereby rotation of said second lower plate is prevented. 8. The suspension tuning kit as set forth in claim 1 wherein said upper plate includes a contoured outer edge, wherein said contoured outer edge is constructed and arranged to permit extended movement of said upper plate with respect to said strut tower. 9. The suspension tuning kit as set forth in claim 8 wherein said upper plate includes at least one rounded corner extending between said bottom surface and said contoured edge, wherein said rounded corner is constructed and arranged to abut an inner fender wall. 10. The suspension tuning kit as set forth in claim 1 wherein said upper plate is made of steel. 11. The suspension tuning kit as set forth in claim 1 wherein said upper plate is made of aluminum. 12. The suspension tuning kit as set forth in claim 1 wherein said upper plate is made of titanium. 13. The suspension tuning kit as set forth in claim 1 wherein said strut mounting plate bore includes at least one snap ring groove, wherein said bore is constructed and arranged to accept a hemispherical connector member, wherein said hemispherical connector member is constructed and arranged to pivotally secure said top end of said strut member, wherein said at least one snap ring groove cooperates with at least one snap ring to secure said hemispherical member. 14. The suspension tuning kit as set forth in claim 1 wherein said camber adjustment range facilitates adjusting said strut axis up to about three degrees. 15. The suspension tuning kit as set forth in claim 1 wherein said camber adjustment range facilitates adjusting said strut axis from about 0 degrees to about −3 degrees. 16. The suspension tuning kit as set forth in claim 1 wherein said caster adjustment facilitates adjusting said strut axis up to about three degrees. 17. The suspension tuning kit as set forth in claim 1 wherein said caster adjustment facilitates adjusting said strut axis from about +4 degrees to about +7 degrees. | FIELD OF THE INVENTION The present invention relates to a device for quickly and easily adjusting the caster and camber of a vehicle front suspension across a broader than normal range to tune the vehicle's suspension for racing and/or high performance street applications. BACKGROUND OF THE INVENTION The versatility and performance of newer muscle cars such as the FORD MUSTANG permit owners to use one vehicle for multiple purposes. Often the same vehicle used to carry groceries home from the supermarket is used for racing applications on the weekend. Owners will often modify their vehicle to make it more competitive in their chosen form of racing. One of the most modified areas of a vehicle for racing applications is the suspension. Front suspension tuning can be one of the most critical aspects of getting a vehicle to handle properly for either street or racing applications. Unfortunately, front suspensions that are modified exclusively for racing typically will not work properly for street driving, and street suspensions typically do not work well for racing. One of the biggest challenges for a muscle car owner who races his vehicle has been to balance the vehicle for both uses. The front wheel of a vehicle has three main alignment angles: camber, caster, and toe. Camber is the angle at which the top of the tire is tilted inwardly or outwardly, as viewed from the front of the car. If the top of the tires lean toward the center of the car you have negative camber. If the top of the tires are tilted outward you have positive camber. Typically, as the tires are turned left and right, the camber changes slightly because the pivoting points for the tires are not vertical as viewed from the side. Adjusting camber can have a dramatic affect on the cornering characteristics of a vehicle. For example, an oval track racer will often race with negative camber on the right side of the vehicle and positive camber on the left side of the vehicle. A drag racer will often race with neutral or slightly negative camber on both sides of the vehicle and a street vehicle will typically have camber set at zero or perpendicular to the street surface. Caster is the angle at which the pivot points for tires are tilted, as viewed from the side. Caster is best understood by imagining an axis running through the uppermost wheel pivot and extending through the lowermost pivot. From the side, if the top of the axis tilts toward the back of the car you have positive caster, if the axis line tilts toward the front of the car you have negative caster. If a vehicle has positive caster, the uppermost pivot is behind the lower pivot and this causes the tire to tilt in more at the top as the tire is steered inward (camber gain). Changing caster primarily affects four things, high speed stability, camber gain, bump steer characteristics and relative corner weights (wedge). Increasing caster generally increases straight line directional stability. This is good for an application such as drag racing, however, other parameters such as bump steer and wedge may be adversely affected making handling for applications such as street driving or road racing unacceptable. Excessive caster settings will increase required steering effort, cause excessive tire wear and reduce braking ability. Negative caster requires less steering effort but directional stability is adversely affected. Some racing applications may require different caster settings on each side of the vehicle. For example, oval track racers often run more positive caster on the right side wheel than the left. The caster split helps pull the car down into the turn, helps the car turn in the center of the turn, and helps the car maintain traction exiting the turn. Accordingly, what is lacking in the art is a suspension tuning kit for vehicles with struts. The suspension tuning kit should achieve objectives such as providing: quick adjustment, increased suspension rigidity, increased range of adjustability reliable performance. The suspension tuning kit should include packaging flexibility for installation on various vehicle configurations including retrofitting existing vehicles with minimal modification of the original suspension system. The suspension tuning kit should facilitate independent caster and camber adjustment of each front wheel across the extended range. The suspension tuning kit should facilitate quick suspension changes to allow a vehicle to be driven to a racetrack, converted to a race setup and thereafter quickly converted back to a street driving setup for the trip home. DESCRIPTION OF THE PRIOR ART A number of prior art systems exist for adjusting the caster and/or camber of a vehicle which utilizes struts. Most of the systems utilize a combination of thin stamped metal plates and rubber bushings, while others use eccentric cams or jack bolts. U.S. Pat. No. 4,372,575 teaches a vehicle wheel suspension including a strut member provided at its lower end with a wheel spindle and a connection with a lateral lower control arm. The device further includes mounting apparatus for attaching the upper end of the strut to a stamped sheet metal tower portion of the vehicle and provisions for adjustment of either wheel caster or wheel camber via a stamped sheet metal adjuster attached to the upper end of the strut. U.S. Pat. No. 4,946,188 teaches an adjustment mechanism for a MacPherson strut of an automobile. The adjustment is provided by modifying the top bearing retainer to provide an inward circular lip. Two plates are clamped to this lip. Before clamping, the plates are rotatable relative to the bearing retainer so that the center of an eccentric hole therein moves along a circle which is concentric to the bearing retainer and thus the bearing. The upper end of the piston rod of the strut is mounted in the eccentric hole so that the position of the upper end of the strut can be moved relative to the body and also within the bearing and helical spring. U.S. Pat. No. 5,484,161 teaches an adjustable mount for the upper end of a motor vehicle suspension strut, wherein a flange is located between a clamping plate and a face plate with studs passing from the clamping plate through enlarged apertures in the flange. Holes in the face plate and aligned holes in the top of the vehicle chassis suspension tower are securable by nuts. Before the nuts are tightened, the flange may be moved in a sliding fashion between the clamping plate and face plate to locate the bushing and upper end of the strut into the desired location for correct caster and camber settings. Reference is also made to the provision of screwdriver slots to permit the flange to be levered into the desired location using a screwdriver when the suspension is under load. U.S. Pat. No. 5,931,485 teaches a support arrangement for a steered vehicle wheel mounted on a wheel carrier which is supported by a transverse link by way of a ball joint with a flange pivotally supported and mounted on the transverse link by clamping screws extending through spaced mounting holes in the transverse link and the mounting flange. The mounting holes in one of the transverse link and mounting flange is formed by at least three different receiving bores disposed at different distances from the pivot point of the flange for receiving the clamping screws and the mounting holes. In the other are holes elongated along a line extending through the pivot point between the transverse link and the flange and forming jointly with the screws stops which provide for positive engagement between the transverse link and the flange in each of the different relative pivot positions between the two. U.S. Pat. No. 6,224,075 teaches a caster adjuster for a motor vehicle suspension, typically having a wishbone. The device is made adjustable by mounting the suspension upright ball joint in a housing having an offset spigot rotatable by an Allen key engaged in the spigot to move the ball joint backward and forward while the spigot is restrained by a slot in a location bracket engaged with the wishbone. Camber is adjusted by a threaded adjuster operable between the location bracket and the housing while allowing rotation of the housing relative to the bracket. U.S. Pat. No. 6,257,601 teaches an adjustable strut mounting plate for correcting at least one alignment parameter of a motor vehicle wheel assembly, with the adjustable strut mounting plate comprising an annular body adapted for secure attachment to the original strut mounting plate of the motor vehicle. The adjustable strut mounting plate includes a plurality of elongated ribbed adjustment bores through which bolts pass to secure the original strut mounting plate to the adjustable mounting plate. In addition, right hand and left hand tower mounting bores are provided in the adjustable strut mounting plate to accommodate attachment of the combined adjustable strut plate with the original strut plate to the vehicle tower. U.S. Pat. No. 6,328,321 teaches an adjustable mount for the upper end of a vehicle suspension strut allowing the strut to be relocated relative to a vehicle chassis member. The mount comprises a bush adapted to receive and secure the upper end of the strut, a flange extending radially outwardly from the bush, and a clamping plate adapted to abut the lower face of the flange. The flange has upper and lower faces, and the clamping plate has an opening therethrough larger than the perimeter of the bush such that the clamping plate can relatively slide over the lower face of the flange over a limited area. A plurality of studs extend upwardly from the clamping plate. The studs are located outside the periphery of the flange and restrict the sliding movement of the flange relative to the clamping plate by engagement with the periphery of the flange. U.S. Pat. No. 6,485,223 teaches a caster-camber plate assembly which includes a base plate, a main plate and a strut top mounting plate. The base plate includes four spaced apart main plate fastening members attached thereto. The main plate includes four spaced apart strut top mounting plate fastening members attached thereto. The main plate has the main plate fastening members extending therethrough for attaching the base plate adjacent to a first side of the main plate and is capable of being moved with respect to the base plate along a first translation axis. The strut top mounting plate is positioned adjacent to the main plate with the four strut top mounting plate fastening members extending therethrough. The strut top mounting plate is capable of being moved with respect to the main plate along a second translation axis. The second translation axis extends approximately perpendicular to the first translation axis. A central axis of the strut top mounting plate is positioned within an area defined between the main plate fastening members and within an area defined between said strut top mounting plate fastening members. The construction of this device places the strut mount plate on top of the main plate, whereby a catastrophic fastener failure will result in the strut being thrust through the vehicle hood and loss of vehicle control. Moreover, the strut mounting position (height) within this device prevents the strut from being positioned at the original equipment manufacturers (OEM) suggested height. Still yet this construction requires spacers between the main plate and the strut tower to accommodate the heads of the fasteners. The spacers reduce the contact area between the main plate and the strut tower thereby reducing rigidity of the vehicle front suspension. As disclosed, the above devices fail to teach or suggest a suspension tuning mechanism capable of the large range of caster and/or camber adjustments required for high performance applications. The prior art is also deficient in teaching a suspension tuning mechanism capable of providing the caster and/or camber travel required to properly align the front wheels of vehicles having lowered ride heights. Still further, the prior art devices do not provide the suspension rigidity and stability required by high performance and/or racing vehicles. SUMMARY OF THE INVENTION The present invention provides a suspension tuning device for vehicles with struts. More specifically the suspension tuning device generally comprises an upper plate, two lower plates and a strut mounting plate. The plates are constructed to mount juxtaposed to a standard strut tower to permit quick front suspension alterations throughout an increased range when compared to the prior art. The pre-existing vehicle strut tower includes a thin sheet metal mounting member constructed for attaching the upper portion of a strut member via a stamped metal plate. The mounting member typically includes three elongated slots arranged to cooperate with the stamped metal plate to permit the upper portion of the strut member to be pivoted inward for a small amount of camber adjustment. The prior art caster/camber adjustment combination provides only a small amount of adjustment and typically requires the strut to be uncoupled or unloaded to complete the adjustment. The instant invention provides a suspension tuning kit which replaces the stamped metal strut attachment plate of the prior art. The upper plate of the instant invention is constructed of billet aluminum and includes increased thickness when compared to the prior art. The upper plate includes a top surface and a bottom surface, the bottom surface positioned juxtaposed to the upper surface of the strut tower to increase the rigidity of the strut tower. The upper plate also includes an outer contoured perimeter and at least one rounded lower corner which allow the plate to be moved over a broad range without interference from the inner fender wall. The upper plate includes four camber adjustment slots extending through the plate with one slot being substantially longer than the other three. The shorter slots are constructed and arranged to cooperate with the existing three camber adjustment slots in the mounting member of the strut tower to permit extended travel. The longer slot cooperates with a round aperture which is drilled through the mounting surface of the strut tower. The longer slot and the added fastener further increase rigidity and stability of the assembly. The upper plate also includes a contoured cavity which extends upward into the upper plate from the bottom surface. The cavity includes a centrally located oval shaped aperture and a plurality of elongated caster adjustment slots arranged substantially transverse to the camber adjustment slots. The contoured cavity and the oval aperture cooperate to partially enclose the strut mounting plate while still permitting the strut mounting plate to slide for caster adjustment. Partially enclosing the strut mounting plate prevents the upper portion of the strut from becoming loose in the event of a fastener failure. The strut mounting plate is preferably machined from a steel billet and includes a flat plate portion and a centrally located upwardly extending boss. The flat plate portion includes a plurality of threaded apertures arranged to align with the elongated caster slots in the upper plate. Fasteners extend through the elongated caster slots in the upper plate and threadably engage the threaded apertures to secure the mounting plate in a predetermined position with respect to the upper plate. The boss includes a centrally located bore adapted to secure the upper end of a strut. The bore may optionally include a resilient isolation element or a hemispherical element for allowing the strut to pivot a predetermined amount. The first lower plate is generally L-shaped and preferably includes three studs affixed substantially perpendicular with respect to one of the side faces. The first lower plate is located juxtaposed to the lower surface of the mounting portion of the strut tower with the studs extending through the pre-existing slots in the mounting member of the strut tower and the three short slots in the upper plate. Three threaded nuts cooperate with the threaded studs extending through the upper plate to allow the upper plate to be secured in a selected position with respect to the strut tower. The second lower plate is generally rectangular and includes one stud affixed substantially perpendicular to one side thereof. The second lower plate is also located juxtaposed to the lower surface of the mounting member of the strut tower with the stud extending through the drilled aperture and the long slot in the upper plate. The second lower plate may also include a means of attaching the second lower plate to the strut tower to prevent rotation thereof during adjustment of the upper plate. A threaded nut cooperates with the threaded stud extending through the drilled aperture and the upper plate to allow the upper plate to be secured in a selected position with respect to the strut tower. The first and second lower plates cooperate with the upper plate to sandwich the mounting member of the strut tower adding significant rigidity and stability to the assembly when compared to the prior art. The suspension tuning kit may be installed on either one or both sides of the front suspension of the vehicle and each strut may be independently adjusted to suit the drivers needs. Accordingly, it is an objective of the present invention to provide a suspension tuning kit for vehicles with struts. Yet an additional objective of the present invention is to provide a suspension tuning kit for vehicles with struts which allows rapid suspension changes without disconnection of the strut. It is a further objective of the present invention to provide a suspension tuning kit for vehicles with struts that allows an increased range of adjustment when compared to prior art devices. A still further objective of the present invention is to provide a suspension tuning kit for vehicles with struts which includes sandwich construction and additional fasteners to provide additional rigidity and support to the vehicle suspension system. Another objective of the present invention is to provide a suspension tuning kit for vehicles with struts which is simple to install and which is ideally suited for original equipment and aftermarket installations. Yet another objective of the present invention is to provide a suspension tuning kit for vehicles with struts that can be inexpensively manufactured and which is simple and reliable in operation. Still another objective of this invention is to provide a suspension tuning kit for vehicles with struts or coil over shocks which utilizes a two piece base plate construction. Still yet another objective of the instant invention is to provide a suspension tuning kit for vehicles with struts which maintains limited control of the strut or coil over shock in the event of a strut mounting plate fastener failure. Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a perspective view illustrating the front portion of a vehicle equipped with strut front suspension; FIG. 2 is a perspective exploded view of the instant invention and a portion of the strut tower mounting member of the vehicle illustrated in FIG. 1; FIG. 3 is a top view of the upper plate of the instant invention; FIG. 4 is a section view of the upper plate taken along lines 1-1 of FIG. 3; FIG. 5 is a bottom perspective view of the upper plate shown in FIG. 3; FIG. 6 is a perspective view of the strut mounting member of the instant invention; FIG. 7 is a top view of the first lower plate of the instant invention; FIG. 8 is a side view of the first lower plate of the instant invention; FIG. 9 is a a top view of the second lower plate of the instant invention; FIG. 10 is a side view of the second lower plate of the instant invention. DETAILED DESCRIPTION OF THE INVENTION Although the invention is described in terms of a preferred specific embodiment, it will be readily apparent to those skilled in this art that various modifications, rearrangements and substitutions can be made without departing from the spirit of the invention. The scope of the invention is defined by the claims appended hereto. Referring to FIG. 1, the front portion of a vehicle 10 equipped with a strut suspension is shown. The strut suspension 12 includes a pair of strut towers 14. The strut towers are typically formed from sheet metal by methods well known in the art and are secured to the inner fender wall structure 18 on both the left side 20 and right side 22 of the vehicle. Each strut tower includes a mounting member 24 oriented in a plane substantially orthogonal with respect to the longitudinal axis 32 of the corresponding strut 16. The mounting member 24 generally includes a strut aperture 26 and three elongated camber adjustment slots 28. The elongated camber adjustment slots are arranged generally parallel with respect to each other and spaced around the strut axis 32. The upper end of a strut member 16 is secured to the mounting member via a stamped sheet metal member 30. The sheet metal member 30 cooperates with the three camber adjustment slots 28 to permit the upper end of the strut member to be pivoted inward toward the center of the car for a small amount of camber adjustment. Referring to FIG. 2, an exploded view of the instant invention is illustrated. The instant invention provides a suspension tuning kit 100 which replaces the stamped metal strut attachment plate 30 (FIG. 1) of the prior art. The suspension tuning kit 100 comprises an upper plate 102, a strut mounting plate 104, a first lower plate 106 and a second lower plate 108. Referring to FIGS. 2-5, the upper plate 102 is illustrated. The upper plate 102 includes an outer contoured edge 120, a top surface 114, a bottom surface 116 and at least one rounded bottom corner 122. In a most preferred and non-limiting embodiment, the upper plate is constructed of aluminum is and is about 0.590 of an inch thick. It should be appreciated that the upper plate may be made thinner or thicker as the space requirements, materials and wheel loads require. The upper plate may alternatively be made from other metals which may include, but should not be limited to steel, titanium or suitable combinations thereof. The contoured outer edge 120 and the rounded bottom corner 122 cooperate to allow the upper plate 102 to be moved over a broad range while assembled juxtaposed to the upper surface to the strut tower without interference between the upper plate 102 and the inner fender wall 18. The radiused lower corner 122 is particularly adapted to allow the upper plate 102 to abut the fillet where the inner fender wall 18 and strut tower 14 (FIG. 1) are joined. The upper plate 102 includes four secondary camber adjustment slots 118, 124 extending through the upper plate with one secondary camber adjustment slot 124 being substantially longer than the other three. The shorter slots 118 are constructed and arranged to cooperate with the existing three camber adjustment slots 28 in the mounting member 24 of the strut tower 14. The longer slot 124 cooperates with a round aperture 126 (FIG. 2) which is drilled through the mounting surface 24 of the strut tower 14. In the preferred embodiment the existing camber adjustment slots 28 cooperate with the secondary camber adjustment slots 118, 124 to allow about three degrees of camber adjustment. In a most preferred embodiment the camber adjustment slots are constructed and arranged to allow wheel camber to be adjusted between about 0 degrees and about −3 degrees. The upper plate 102 also includes a contoured cavity 126 which extends upward into the bottom surface 116 and a centrally located oval shaped aperture 128. The contoured cavity 126 and the oval aperture 128 cooperate to partially enclose the strut mounting plate while permitting caster adjustment with or without disconnection of the strut member 16 (FIG. 1). In a most preferred non-limiting embodiment, the cavity extends about 0.300 of an inch into the upper plate. It should also be appreciated that the cavity depth may be varied to accommodate space, material and wheel load requirements. At least two caster adjustment slots 130, 131 extend through the top surface 114 into the cavity 126 and are arranged to have substantially transverse axis to the camber adjustment slots 118 and 124. In the preferred embodiment one of the caster adjustment slots 131 is longer than caster adjustment slot 130. The longer caster adjustment slot 131 is constructed and arranged to accommodate two spaced apart fasteners for increased securement of the strut mounting plate. In the preferred embodiment the caster adjustment slots 130, 131 are constructed and arranged to allow about 3 degrees of adjustment. In a most preferred embodiment, the caster adjustment slots allow the caster to be adjusted between about +4 degrees to about +7 degrees. Referring to FIG. 6, a strut mounting plate 104 is illustrated. In the preferred embodiment, the strut mounting plate includes a flat plate portion 132 and an integrally formed upwardly extending boss 134. The outer edge 138 of the flat plate portion is contoured and sized to fit into the upper plate cavity 126 (FIG. 5). The flat plate portion includes at least two and preferably three threaded apertures 136. The apertures are arranged to align with the caster adjustment slots 130, 131 in the upper plate 102. A plurality of threaded fasteners (not shown) extend through the upper plate caster slots 130, 131 and cooperate with the threaded apertures 136 to permit the strut mounting plate to be secured in a desired position with respect to the upper plate. In a most preferred embodiment the flat plate portion is about 0.285 of an inch thick. The thickness of the flat plate portion and the upper plate cavity depth cooperate to allow the strut mounting plate to be slid into a desired caster position while the upper plate is secured in place with respect to the strut tower. The upwardly extending boss 134 includes a bore 140 extending therethrough. The bore is constructed and arranged to secure the upper end of a strut member 16 (FIG. 1). In the preferred embodiment the bore 140 includes a resilient member or hemispherical member (not shown). Snap rings, well known in the art, cooperate with an upper snap ring groove 142 and a lower snap ring groove 144 to retain the resilient or hemispherical member within the bore. The resilient member and the hemispherical member are constructed and arranged to cooperate with the upper end of the strut member 16 to allow the strut member to pivot a predetermined amount. The strut mounting plate 104 is preferably machined as a single piece from a metal such as steel. However, other materials such as aluminum and/or titanium may also be used. In addition, the strut mounting plate may be made from a plurality of pieces and attached together by methods well known in the art. Referring to FIGS. 7-8, the first lower plate 106 is illustrated. The first lower plate is generally L-shaped and includes three fastener apertures 146 therethrough. The three fastener apertures are constructed and arranged to align with the strut tower camber slots 28 and the upper plate camber adjustment slots 118 (FIG. 2). In the preferred embodiment a first group of threaded fasteners 148 extend through the fastener apertures 146 and the heads are secured to the lower side face 152 via weldment. The first lower plate 106 is positioned parallel and juxtaposed to the bottom surface of the mounting member 24 of the strut tower 14. The first group of threaded fasteners 148 have sufficient length to extend through the mounting member of the strut tower and the upper plate. At least three threaded nuts (Not shown) cooperate with said first group of fasteners to secure the upper plate in a selected position with respect to the strut tower. Referring to FIGS. 9-10, the second lower plate 154 is illustrated. The second lower plate is generally rectangular and includes a beveled corner 156 and at least one aperture 146. In the preferred embodiment a fourth threaded fastener 148 extends through the fastener aperture 146 and the head of the fastener is secured to the lower side face 158 via weldment. The second lower plate 108 is positioned parallel and juxtaposed to the bottom surface of the mounting member 24 of the strut tower 14. The threaded fastener 148 has sufficient length to extend through the drilled aperture 126 in the mounting member of the strut tower and the upper plate 102. A threaded nut (not shown) cooperates with the fourth fastener to secure the upper plate in a selected position with respect to the strut tower. In this manner, the front wheel camber of a vehicle may be selectively adjusted along an extended axis by loosening the first group of three fasteners and the fourth threaded fastener for movement of the upper plate, first lower plate and second lower plate relative to the mounting member of the strut tower. Once the plates have been positioned to cause the front wheel to have the desired amount of camber the nuts are tightened by means well known in the art to secure the plates and thereby the wheel in place. The front wheel caster may be selectively adjusted along an extended axis by loosening the third group of threaded fasteners for movement of the strut mounting plate relative to the upper plate and the mounting member of the strut tower. The construction of the suspension tuning device allows the wheel caster to be adjusted without loosening the upper plate and without adjusting camber settings. All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification. One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims. | <SOH> BACKGROUND OF THE INVENTION <EOH>The versatility and performance of newer muscle cars such as the FORD MUSTANG permit owners to use one vehicle for multiple purposes. Often the same vehicle used to carry groceries home from the supermarket is used for racing applications on the weekend. Owners will often modify their vehicle to make it more competitive in their chosen form of racing. One of the most modified areas of a vehicle for racing applications is the suspension. Front suspension tuning can be one of the most critical aspects of getting a vehicle to handle properly for either street or racing applications. Unfortunately, front suspensions that are modified exclusively for racing typically will not work properly for street driving, and street suspensions typically do not work well for racing. One of the biggest challenges for a muscle car owner who races his vehicle has been to balance the vehicle for both uses. The front wheel of a vehicle has three main alignment angles: camber, caster, and toe. Camber is the angle at which the top of the tire is tilted inwardly or outwardly, as viewed from the front of the car. If the top of the tires lean toward the center of the car you have negative camber. If the top of the tires are tilted outward you have positive camber. Typically, as the tires are turned left and right, the camber changes slightly because the pivoting points for the tires are not vertical as viewed from the side. Adjusting camber can have a dramatic affect on the cornering characteristics of a vehicle. For example, an oval track racer will often race with negative camber on the right side of the vehicle and positive camber on the left side of the vehicle. A drag racer will often race with neutral or slightly negative camber on both sides of the vehicle and a street vehicle will typically have camber set at zero or perpendicular to the street surface. Caster is the angle at which the pivot points for tires are tilted, as viewed from the side. Caster is best understood by imagining an axis running through the uppermost wheel pivot and extending through the lowermost pivot. From the side, if the top of the axis tilts toward the back of the car you have positive caster, if the axis line tilts toward the front of the car you have negative caster. If a vehicle has positive caster, the uppermost pivot is behind the lower pivot and this causes the tire to tilt in more at the top as the tire is steered inward (camber gain). Changing caster primarily affects four things, high speed stability, camber gain, bump steer characteristics and relative corner weights (wedge). Increasing caster generally increases straight line directional stability. This is good for an application such as drag racing, however, other parameters such as bump steer and wedge may be adversely affected making handling for applications such as street driving or road racing unacceptable. Excessive caster settings will increase required steering effort, cause excessive tire wear and reduce braking ability. Negative caster requires less steering effort but directional stability is adversely affected. Some racing applications may require different caster settings on each side of the vehicle. For example, oval track racers often run more positive caster on the right side wheel than the left. The caster split helps pull the car down into the turn, helps the car turn in the center of the turn, and helps the car maintain traction exiting the turn. Accordingly, what is lacking in the art is a suspension tuning kit for vehicles with struts. The suspension tuning kit should achieve objectives such as providing: quick adjustment, increased suspension rigidity, increased range of adjustability reliable performance. The suspension tuning kit should include packaging flexibility for installation on various vehicle configurations including retrofitting existing vehicles with minimal modification of the original suspension system. The suspension tuning kit should facilitate independent caster and camber adjustment of each front wheel across the extended range. The suspension tuning kit should facilitate quick suspension changes to allow a vehicle to be driven to a racetrack, converted to a race setup and thereafter quickly converted back to a street driving setup for the trip home. | <SOH> SUMMARY OF THE INVENTION <EOH>The present invention provides a suspension tuning device for vehicles with struts. More specifically the suspension tuning device generally comprises an upper plate, two lower plates and a strut mounting plate. The plates are constructed to mount juxtaposed to a standard strut tower to permit quick front suspension alterations throughout an increased range when compared to the prior art. The pre-existing vehicle strut tower includes a thin sheet metal mounting member constructed for attaching the upper portion of a strut member via a stamped metal plate. The mounting member typically includes three elongated slots arranged to cooperate with the stamped metal plate to permit the upper portion of the strut member to be pivoted inward for a small amount of camber adjustment. The prior art caster/camber adjustment combination provides only a small amount of adjustment and typically requires the strut to be uncoupled or unloaded to complete the adjustment. The instant invention provides a suspension tuning kit which replaces the stamped metal strut attachment plate of the prior art. The upper plate of the instant invention is constructed of billet aluminum and includes increased thickness when compared to the prior art. The upper plate includes a top surface and a bottom surface, the bottom surface positioned juxtaposed to the upper surface of the strut tower to increase the rigidity of the strut tower. The upper plate also includes an outer contoured perimeter and at least one rounded lower corner which allow the plate to be moved over a broad range without interference from the inner fender wall. The upper plate includes four camber adjustment slots extending through the plate with one slot being substantially longer than the other three. The shorter slots are constructed and arranged to cooperate with the existing three camber adjustment slots in the mounting member of the strut tower to permit extended travel. The longer slot cooperates with a round aperture which is drilled through the mounting surface of the strut tower. The longer slot and the added fastener further increase rigidity and stability of the assembly. The upper plate also includes a contoured cavity which extends upward into the upper plate from the bottom surface. The cavity includes a centrally located oval shaped aperture and a plurality of elongated caster adjustment slots arranged substantially transverse to the camber adjustment slots. The contoured cavity and the oval aperture cooperate to partially enclose the strut mounting plate while still permitting the strut mounting plate to slide for caster adjustment. Partially enclosing the strut mounting plate prevents the upper portion of the strut from becoming loose in the event of a fastener failure. The strut mounting plate is preferably machined from a steel billet and includes a flat plate portion and a centrally located upwardly extending boss. The flat plate portion includes a plurality of threaded apertures arranged to align with the elongated caster slots in the upper plate. Fasteners extend through the elongated caster slots in the upper plate and threadably engage the threaded apertures to secure the mounting plate in a predetermined position with respect to the upper plate. The boss includes a centrally located bore adapted to secure the upper end of a strut. The bore may optionally include a resilient isolation element or a hemispherical element for allowing the strut to pivot a predetermined amount. The first lower plate is generally L-shaped and preferably includes three studs affixed substantially perpendicular with respect to one of the side faces. The first lower plate is located juxtaposed to the lower surface of the mounting portion of the strut tower with the studs extending through the pre-existing slots in the mounting member of the strut tower and the three short slots in the upper plate. Three threaded nuts cooperate with the threaded studs extending through the upper plate to allow the upper plate to be secured in a selected position with respect to the strut tower. The second lower plate is generally rectangular and includes one stud affixed substantially perpendicular to one side thereof. The second lower plate is also located juxtaposed to the lower surface of the mounting member of the strut tower with the stud extending through the drilled aperture and the long slot in the upper plate. The second lower plate may also include a means of attaching the second lower plate to the strut tower to prevent rotation thereof during adjustment of the upper plate. A threaded nut cooperates with the threaded stud extending through the drilled aperture and the upper plate to allow the upper plate to be secured in a selected position with respect to the strut tower. The first and second lower plates cooperate with the upper plate to sandwich the mounting member of the strut tower adding significant rigidity and stability to the assembly when compared to the prior art. The suspension tuning kit may be installed on either one or both sides of the front suspension of the vehicle and each strut may be independently adjusted to suit the drivers needs. Accordingly, it is an objective of the present invention to provide a suspension tuning kit for vehicles with struts. Yet an additional objective of the present invention is to provide a suspension tuning kit for vehicles with struts which allows rapid suspension changes without disconnection of the strut. It is a further objective of the present invention to provide a suspension tuning kit for vehicles with struts that allows an increased range of adjustment when compared to prior art devices. A still further objective of the present invention is to provide a suspension tuning kit for vehicles with struts which includes sandwich construction and additional fasteners to provide additional rigidity and support to the vehicle suspension system. Another objective of the present invention is to provide a suspension tuning kit for vehicles with struts which is simple to install and which is ideally suited for original equipment and aftermarket installations. Yet another objective of the present invention is to provide a suspension tuning kit for vehicles with struts that can be inexpensively manufactured and which is simple and reliable in operation. Still another objective of this invention is to provide a suspension tuning kit for vehicles with struts or coil over shocks which utilizes a two piece base plate construction. Still yet another objective of the instant invention is to provide a suspension tuning kit for vehicles with struts which maintains limited control of the strut or coil over shock in the event of a strut mounting plate fastener failure. Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. | 20040402 | 20061205 | 20051006 | 63839.0 | 2 | CULBRETH, ERIC D | FRONT SUSPENSION TUNING APPARATUS FOR VEHICLE WITH STRUTS | SMALL | 0 | ACCEPTED | 2,004 |
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10,816,676 | ACCEPTED | Totes for bottles | According to another aspect of the present disclosure, a carrier for transporting a bottle or bottles, is provided. The carrier includes a tote having a non-rigid front and rear panel secured to one another along a right side terminal edge, a left side terminal edge and a bottom terminal edge to thereby define a pocket having an open top. A contact line is provided between the right side terminal edge and the left side terminal edge to divide the pocket into a first and a second pocket. The bottom terminal edge is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped bottom terminal edge, wherein the tote is fabricated from neoprene. | 1. A tote for carrying and transporting a bottle or bottles, the tote comprises: a front panel defining a right side, a left side, a bottom, and a top terminal edge; and a rear panel defining a right side, a left side, a bottom, and a top terminal edge, the rear panel being secured to the front panel along at least the right side, the left side and the bottom terminal edges, the front and rear panels defining a pocket therebetween, wherein at least one of the front and rear panels are fabricated from an elastic, insulative, impact absorbent material, and wherein the tote has a substantially flattened condition when no bottle is disposed in the pocket thereof. 2. The tote according to claim 1, wherein the front and rear panels are fabricated from neoprene. 3. The tote according to claim 2, wherein the front and rear panels have a thickness of between about 3 mm to about 5 mm. 4. The tote according to claim 2, wherein the neoprene is sandwiched between layers of stretch nylon. 5. The tote according to claim 4, wherein the bottom terminal edges of the front and rear panels are arcuate when the tote is in the flattened condition. 6. The tote according to claim 5, wherein when a bottle is at least partially inserted into the opening between the front and rear panels, the arcuate bottom terminal edge thereof flattens. 7. The tote according to claim 6, wherein the front and rear panels are secured to one another by at least one of stitching, adhering, welding, and stapling. 8. The tote according to claim 7, wherein at least one of the front and rear panels includes an aperture formed therein. 9. The tote according to claim 8, wherein the upper terminal edges of the front and rear panels are arcuate. 10. The tote according to claim 9, wherein the front panel and the rear panel are secured to one another along a contact line positioned between the right side terminal edges and the left side terminal edges thereof. 11. The tote according to claim 10, wherein the contact line divides the pocket between the front and rear panels into a first pocket and a second pocket. 12. The tote according to claim 11, wherein the bottom terminal edges of each of the front and rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket. 13. The tote according to claim 12, further comprising: a third panel defining a right side, a left side, a bottom, and a top terminal edge; wherein the right side terminal edge of the front panel is secured to the left side terminal edge of the rear panel, and a portion of the bottom terminal edge of the front panel is secured to the bottom terminal edge of the rear panel; wherein the right side terminal edge of the rear panel is secured to the left side terminal edge of the third panels, and a portion of the bottom terminal edge of the rear panel is secured to a portion of the bottom terminal edge of the third panel; and wherein the right side terminal edge of the third panel is secured to the left side terminal edge of the front panel, and a portion of the bottom terminal edge of the third panel is secured to a portion of the bottom terminal edge of the front panel. 14. The tote according to claim 13, wherein the front, rear and third panels are secured to one another along a contact line substantially centrally located between the right and left side terminal edges of each of the front, the rear and the third panels. 15. The tote according to claim 12, comprising: a first front panel defining a right side, a left side, a bottom, and a top terminal edge; a first rear panel defining a right side, a left side, a bottom, and a top terminal edge, the first rear panel being secured to the first front panel along at least the right side, the left side and the bottom terminal edges, the first front and first rear panels being secured to one another along a first contact line positioned between the right side terminal edges and the left side terminal edges thereof, wherein the first contact line defines a first pocket and a second pocket between the first front panel and the first rear panel, wherein the bottom terminal edges of each of the first front and first rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket; a second front panel defining a right side, a left side, a bottom, and a top terminal edge; and a second rear panel defining a right side, a left side, a bottom, and a top terminal edge, the second rear panel being secured to the second front panel along at least the right side, the left side and the bottom terminal edges, the second front and second rear panels being secured to one another along a second contact line positioned between the right side terminal edges and the left side terminal edges thereof, wherein the second contact line defines a third pocket and a fourth pocket between the second front panel and the second rear panel, wherein the bottom terminal edges of each of the second front and second rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the third pocket and a second lobe of the bottom terminal edge is in operative association with the fourth pocket, wherein the first contact line is secured to the second contact line. 16. The tote according to claim 15, further comprising: a tote strap for selectively engaging the tote, the tote strap including: a hook member for selectively engaging a support structure; and a loop extending from the hook member, the loop having sufficient length to be fed through the hand hold of the tote and for the hook member to then be fed through the loop. 17. A tote for carrying and transporting a bottle or bottles, the tote comprises: a front panel defining a perimetral edge; and a rear panel defining a perimetral edge, the front panel being secured to the rear panel along at least a portion of the perimetral edge so as to define a pocket therebetween and an opening into the pocket, wherein the front and rear panels are fabricated from an elastic, insulative, impact absorbent material. 18. The tote according to claim 17, wherein the front and rear panels are fabricated from neoprene laminated between two layers of stretch nylon. 19. The tote according to claim 18, wherein the front and rear panels are secured to one another along a contact line extending in a direction orthogonal to the opening, wherein the contact line divides the pocket into a first and a second pocket, wherein the terminal edge opposite the opening is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped terminal edge. 20. A carrier for transporting a bottle or bottles, the carrier comprises: a tote having a non-rigid front and rear panel secured to one another along a right side terminal edge, a left side terminal edge and a bottom terminal edge to thereby define a pocket having an open top, wherein a contact line is provided between the right side terminal edge and the left side terminal edge to divide the pocket into a first and a second pocket, wherein the bottom terminal edge is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped bottom terminal edge, wherein the tote is fabricated from neoprene. | CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 60/535,443, filed on Jan. 9, 2004, the entire content of which is incorporated herein by reference. BACKGROUND 1. Technical Field The present disclosure relates to portable bottle carriers and, more particularly, to tote bags suitable for carrying at least one bottle of wine. 2. Background of Related Art Heretofore, when carrying wine bottles in a paper bag, sack or the like, the glass wine bottles, unless restrained or held separated in the bag, could jostle against each other with the result that one or more bottles may break. Even if the bag is carefully handled to prevent breakage of the bottles, the bottles still may strike against each other such that a ringing or other irritating sound is produced. Moreover, the relatively thin nature of the paper bag or sack renders the bottles contained therein vulnerable to breakage as the result of the paper bag or sack striking and/or banging against another object. In addition, paper bags or sacs are incapable of independently retaining the bottle therein, thereby resulting in bottles slipping out of or otherwise disassociating from the paper bag or sac upon transport thereof. Conventional bags and/or sacs are incapable of regulating and/or maintaining the temperature of the bottle retained therein for an extended period of time. In addition, conventional bags and/or sacs are incapable of protecting and/or otherwise cushioning the bottle against impacts and the like. A need therefore exists for a portable wine bottle carrier which reduces the tendency of breakage of the bottles being transported therein, which prevents the bottles from striking one another so as to eliminate any irritating sounds resulting therefrom, and/or which reduces the tendency for bottles to become disassociated therefrom. Such carrier desirably should be conveniently totable and desirably should be aesthetically pleasing in appearance. SUMMARY The present disclosure relates to portable bottle carriers (i.e., tote bags) for carrying at least one bottle therein, preferably a bottle of wine therein. According to one aspect of the present disclosure, a tote for carrying and transporting a bottle or bottles, is provided. The tote includes a front panel defining a right side, a left side, a bottom, and a top terminal edge, and a rear panel defining a right side, a left side, a bottom, and a top terminal edge. The rear panel is secured to the front panel along at least the right side, the left side and the bottom terminal edges. The front and rear panels define a pocket therebetween. The front and/or rear panel is fabricated from an elastic, insulative, impact absorbent material. The tote has a substantially flattened condition when no bottle is disposed in the pocket thereof. Preferably, the front and rear panels are fabricated from neoprene. The front and rear panels may have a thickness of between about 3 mm to about 5 mm. Preferably, the neoprene is sandwiched between layers of stretch nylon. The bottom terminal edges of the front and rear panels are arcuate when the tote is in the flattened condition. Accordingly, when a bottle is at least partially inserted into the opening between the front and rear panels, the arcuate bottom terminal edge thereof flattens. Preferably, the front and rear panels are secured to one another by at least one of stitching, adhering, welding, and stapling. Desirably, at least one of the front and rear panels includes an aperture formed therein. The upper terminal edges of the front and rear panels may be arcuate. In one embodiment, the front panel and the rear panel are secured to one another along a contact line positioned between the right side terminal edges and the left side terminal edges thereof. The contact line divides the pocket between the front and rear panels into a first pocket and a second pocket. The bottom terminal edges of each of the front and rear panels is scalloped. Accordingly, a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket. In another embodiment, the tote further includes a third panel defining a right side, a left side, a bottom, and a top terminal edge. Accordingly, the right side terminal edge of the front panel is secured to the left side terminal edge of the rear panel, and a portion of the bottom terminal edge of the front panel is secured to the bottom terminal edge of the rear panel; the right side terminal edge of the rear panel is secured to the left side terminal edge of the third panels, and a portion of the bottom terminal edge of the rear panel is secured to a portion of the bottom terminal edge of the third panel; and the right side terminal edge of the third panel is secured to the left side terminal edge of the front panel, and a portion of the bottom terminal edge of the third panel is secured to a portion of the bottom terminal edge of the front panel. The front, rear and third panels may be secured to one another along a contact line substantially centrally located between the right and left side terminal edges of each of the front, the rear and the third panels. In yet another embodiment, the tote includes a first front panel defining a right side, a left side, a bottom, and a top terminal edge, and a first rear panel defining a right side, a left side, a bottom, and a top terminal edge. The first rear panel is secured to the first front panel along at least the right side, the left side and the bottom terminal edges. The first front and first rear panels are secured to one another along a first contact line positioned between the right side terminal edges and the left side terminal edges thereof. The first contact line defines a first pocket and a second pocket between the first front panel and the first rear panel. The bottom terminal edge of each of the first front and first rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket. In the present embodiment, the tote further includes a second front panel defining a right side, a left side, a bottom, and a top terminal edge, and a second rear panel defining a right side, a left side, a bottom, and a top terminal edge, the second rear panel being secured to the second front panel along at least the right side, the left side and the bottom terminal edges. The second front and second rear panels are secured to one another along a second contact line positioned between the right side terminal edges and the left side terminal edges thereof. The second contact line defines a third pocket and a fourth pocket between the second front panel and the second rear panel. The bottom terminal edges of each of the second front and second rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the third pocket and a second lobe of the bottom terminal edge is in operative association with the fourth pocket. Preferably, the first contact line is secured to the second contact line. The tote may further include a tote strap for selectively engaging the tote. The tote strap includes a hook member for selectively engaging a support structure; and a loop extending from the hook member. The loop has sufficient length to be fed through the hand hold of the tote and for the hook member to then be fed through the loop. According to another aspect of the present disclosure, a tote for carrying and transporting a bottle or bottles is provided. The tote includes a front panel defining a perimetral edge; and a rear panel defining a perimetral edge. The front panel is secured to the rear panel along at least a portion of the perimetral edge so as to define a pocket therebetween and an opening into the pocket. The front and rear panels are fabricated from an elastic, insulative, impact absorbent material. The front and rear panels are preferably fabricated from neoprene laminated between two layers of stretch nylon. The front and rear panels are secured to one another along a contact line extending in a direction orthogonal to the opening. The contact line divides the pocket into a first and a second pocket, wherein the terminal edge opposite the opening is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped terminal edge. According to another aspect of the present disclosure, a carrier for transporting a bottle or bottles, is provided. The carrier includes a tote having a non-rigid front and rear panel secured to one another along a right side terminal edge, a left side terminal edge and a bottom terminal edge to thereby define a pocket having an open top. A contact line is provided between the right side terminal edge and the left side terminal edge to divide the pocket into a first and a second pocket. The bottom terminal edge is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped bottom terminal edge, wherein the tote is fabricated from neoprene. BRIEF DESCRIPTION OF THE DRAWINGS By way of example only, preferred embodiments of the disclosure will be described with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of a tote according to an embodiment of the present disclosure, shown in a first condition; FIG. 2 is a plan view of the tote of FIG. 1; FIG. 3 is a plan view of the tote of FIGS. 1 and 2, in a second condition including a pair of bottles retained therein; FIG. 4 is a perspective view of the tote of FIGS. 1-3, while in the second condition; FIG. 5 is a front elevational view of the tote of FIGS. 1-4, while in the second condition, with a flap thereof turned down; FIG. 6 is a plan view of a tote according to another embodiment of the present disclosure; FIG. 7 is a perspective view of a tote according to yet another embodiment of the present disclosure; FIG. 8 is a perspective view of a tote according to still another embodiment of the present disclosure; and FIG. 9 is a perspective view of a tote strap for use in connection with any of the totes of the present disclosure. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now in detail to the drawings and initially to FIGS. 1-5, a bottle tote constructed in accordance with the present disclosure is designated generally by reference numeral 100. Tote 100 includes a front panel 102 and a rear panel 104 operatively secured to one another along a number of sides thereof. Preferably, each panel 102, 104 includes a right side edge 102a, 104a, respectively, a left side edge 102b, 104b, respectively, a bottom edge 102c, 104c, respectively, and a top edge 102d, 104d, respectively. Preferably, front panel 102 is secured to rear panel 104 along at least three side edges thereof, namely, right side edge 102a, 104a, left side edge 102b, 104b, and bottom edge 102c, 104c. Front panel 102 is preferably secured to rear panel 104 by stitching along right side edges 102a, 104a, left side edges 102b, 104b and bottom edges 102c, 104c. While stitching is preferred, it is envisioned that front panel 102 can be secured to rear panel 104 by adhering, welding, stapling and the like. Top edges 102d, 104d are preferably separated from one another to define an opening 106 into tote 100. Desirably, front panel 102 and rear panel 104 are secured (e.g., stitched, glued, welded, etc.) to one another along a contact line 108 located between right side edges 102a, 104a and left side edges 102b, 104b. Contact line 108 is preferably longitudinally oriented to thereby define a pair of bottle receiving pockets or cavities 110a, 110b. While it is desirably that contact line 108 be centrally positioned between right side edge 102a, 104a, and left side edge 102b, 104b, to thereby define pockets 110a, 110b having substantially the same dimensions, it is envisioned and within the scope of the present disclosure for contact line 108 to be positioned closer to right side edge 102a, 104a or left side edge 102b, 104b, to thereby define pockets 110a, 110b having different dimensions from one another. Top edges 102d, 104d of front and rear panels 102, 104 can be rounded wherein top edges 102d, 104d commence where right side edges 102a, 104a and left side edges 102b, 104b terminate, thereby defining a front flap 112 and a rear flap 114, respectively. Bottom edges 102c, 104c of front and rear panels 102, 104 are preferably scalloped, defined by a pair of lobes 116, 118. Preferably, each pocket 110a, 110b of tote 100 is in registration with a respective lobe 116, 118 (i.e., contact line 108 is axially aligned with the intersection of lobes 116, 118). As will be discussed in greater detail below, lobes 116, 118 allow tote 100 to: 1) store flat when not in use; and 2) stand upright when bottles are fully inserted therein. Each panel 102, 104 of tote 100 is preferably fabricated from neoprene rubber, more preferably, CR+(100%) neoprene rubber having stretch nylon laminated to the front and back thereof. Each panel 102, 104 preferably has a thickness of between about 3 mm to about 5 mm. The neoprene rubber material acts as a shock absorber to dissipate and/or otherwise absorb forces which may impact on tote 100. Fabrication of tote 100 from neoprene rubber material allows for tote 100 to be fabricated with no moving parts or separate parts/hardware and yet at the same time substantially grip the bottle retained therein. Since the neoprene rubber material has a degree of resiliency, tote 100 can accommodate receipt of and retention of bottles of varying sizes (e.g., bottles having uniform and/or non-uniform diameters along the length thereof, bottles of various diameters and non-circular bottles). The neoprene rubber material also provides tote 100 with a degree of insulation greater that a tote fabricated from paper or the like and thereby allows tote 100 to better maintain the temperature of the bottle(s) retained therein. Desirably, front panel 102 and rear panel 104 includes an aperture 120 formed therein defining a hand hold. Preferably, if tote 100 is fabricated from a neoprene rubber material, the hand hold is provided with a degree of comfort for the carrier. As seen in FIGS. 1 and 2, tote 100 has a first configuration wherein tote 100 is substantially flat, i.e., front panel 102 is at least substantially in contact with rear panel 104. In this manner, when tote 100 is not in use, tote 100 can advantageously be stored in a substantially flat configuration, rolled-up, or otherwise manipulated as needed. As seen in FIGS. 3-5, tote 100 has a second configuration wherein tote 100 substantially conforms to the shape and/or outer contour of a bottle “B” placed and/or inserted into pockets 110a, 110b. When one bottle “B”, preferably two bottles “B”, is/are fully inserted into one or each cavity 110a, 110b, front panel 102 is separated from rear panel 104 and the respective lobe 116, 118, advantageously flattens to allow tote 100 to stand upright. Since tote 100 is preferably fabricated from neoprene and has a degree of elasticity, tote 100 substantially conforms to the contour and/or shape of bottles “B” and effectively grips bottles “B”, thereby effectively reducing the tendency for bottles “B” to “slip out off” pockets 110a, 110b. In addition, the neoprene provides tote 100 with a degree of cushion thereby absorbing impacts and shocks which would otherwise be transmitted to bottles “B”. For example, the location of contact line 108 and the size of pockets 110a, 110b may be selected to accommodate bottles “B” which are sized to hold at least 500 ml, 750 ml, 1L and 1.5L of fluid. Additionally, contact line 108 separates pocket 110a from pocket 110b, thereby eliminating and/or reducing the tendency of the adjacent bottles “B” from contacting and/or otherwise banging into one another, thereby reducing the chances of breakage and reducing the incidents of clanking. Moreover, the neoprene construction acts like an insulator to aid in the maintenance of bottles “B” in a chilled condition if desired. If desired, one pocket 110a, 110b can contain a chilled bottle “B” while the other pocket 110a, 110b can contain an un-chilled bottle “B”. In this manner, the chilled bottle will remain relatively colder and the un-chilled bottle will remain relatively warmer. Turning now to FIG. 6, a tote in accordance with another embodiment of the present disclosure is generally designated as 200. Tote 200 is substantially similar to tote 100 except that tote 200 includes a single pocket (not shown), for retaining a single bottle therein. Similar to tote 100, tote 200 has a first configuration in which tote 200 is substantially flat and a second configuration in which tote 200 substantially conforms to the contour of the bottle placed therein. When the bottle is fully inserted into the pocket of tote 200, the bottom of tote 200 becomes substantially flat, allowing for tote 200 to stand in an upright condition. Turning now to FIG. 7, a tote in accordance with yet another embodiment of the present disclosure is generally designated as 300. Tote 300 is substantially similar to tote 100 and will only be discussed in detail to the extent necessary to identify differences in construction and operation. Tote 300 includes a first panel 302, a second panel 304, and a third panel 305 operatively secured to one another along a number of sides thereof. Preferably, each panel 302, 304 and 305 includes a side edge 302a, 304a and 305a, respectively, a side edge 302b, 304b and 305b, respectively, a bottom edge 302c, 304c and 305c, respectively, and a top edge 302d, 304d and 305d, respectively. Preferably, first panel 302 is secured (e.g., stitched, adhered, welded, etc.) to second panel 304 along at least two side edges thereof, namely, side edge 302b, 304a, and one half of bottom edge 302c, 304c. Second panel 304 is secured to third panel 305 along at least two side edges thereof, namely, side edge 304b and 305a respectively, and one half of bottom edge 304c 305c, respectively. Third panel 305 is secured to first panel 302 along at least two side edges thereof, namely, side edge 305b and 302a, and one half of bottom edge 305c, 302c. First, second and third panels 302, 304 and 305 are preferably secured to one another along a contact line 308 substantially centrally located. Contact line 308 is preferably longitudinally oriented to thereby define three bottle receiving pockets or cavities 310a, 310b and 310c. Tote 300 is essentially in the form of a triad. Turning now to FIG. 8, a tote in accordance with still another embodiment of the present disclosure is generally designated as 400. Tote 400 is substantially similar to tote 100 and will only be discussed in detail to the extent necessary to identify differences in construction and operation. Tote 400 is essentially a pair of totes 100 operatively secured to one another. In this manner, tote 400 includes two pairs of or four bottle receiving pockets or cavities 410a-410d. While four flaps 412a-412d are shown, providing the contents of tote 400 with the maximum amount of protection, it is envisioned and contemplated that any number of flaps 412 are possible. Similar to tote 100, tote 400 has a first configuration in which tote 400 is substantially flat, as seen in FIG. 8, and a second configuration in which tote 400 substantially conforms to the contour of bottles placed therein. When bottles are fully inserted into pockets 410a-410d of tote 400, the bottom of tote 400 becomes substantially flat, allowing for tote 400 to stand in an upright condition. Tote 400 can essentially be considered a quad tote. As seen in FIG. 9, a tote strap 500 can be provided for attaching and/or otherwise connecting any of totes 100-400 to a rolling travel bag, a shopping cart, an vehicle or the like. Tote strap 500 includes a hook member 502 fabricated from a rigid material, e.g., rigid plastics, composites, metals and the like. Tote strap 500 further includes a loop 504 extending from hook member 502. Loop 504 preferably has a length sufficient for loop 504 to be fed through hand hold 120 of tote 100 and then hook member 502 is fed through loop 504 and pulled or cinched to thereby tighten loop 504. Hook member 502 can then be connected to the rolling baggage, the shopping cart, the vehicle or the like. It will be understood that various modifications may be made to the embodiments disclosed herein. For example, while totes for 1-4 bottles have been shown and described, it is envisioned that totes for any number of bottles can be provided by combining any of the totes disclosed herein. Accordingly, the above description should not be construed as limiting, but merely as an exemplification of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. | <SOH> BACKGROUND <EOH>1. Technical Field The present disclosure relates to portable bottle carriers and, more particularly, to tote bags suitable for carrying at least one bottle of wine. 2. Background of Related Art Heretofore, when carrying wine bottles in a paper bag, sack or the like, the glass wine bottles, unless restrained or held separated in the bag, could jostle against each other with the result that one or more bottles may break. Even if the bag is carefully handled to prevent breakage of the bottles, the bottles still may strike against each other such that a ringing or other irritating sound is produced. Moreover, the relatively thin nature of the paper bag or sack renders the bottles contained therein vulnerable to breakage as the result of the paper bag or sack striking and/or banging against another object. In addition, paper bags or sacs are incapable of independently retaining the bottle therein, thereby resulting in bottles slipping out of or otherwise disassociating from the paper bag or sac upon transport thereof. Conventional bags and/or sacs are incapable of regulating and/or maintaining the temperature of the bottle retained therein for an extended period of time. In addition, conventional bags and/or sacs are incapable of protecting and/or otherwise cushioning the bottle against impacts and the like. A need therefore exists for a portable wine bottle carrier which reduces the tendency of breakage of the bottles being transported therein, which prevents the bottles from striking one another so as to eliminate any irritating sounds resulting therefrom, and/or which reduces the tendency for bottles to become disassociated therefrom. Such carrier desirably should be conveniently totable and desirably should be aesthetically pleasing in appearance. | <SOH> SUMMARY <EOH>The present disclosure relates to portable bottle carriers (i.e., tote bags) for carrying at least one bottle therein, preferably a bottle of wine therein. According to one aspect of the present disclosure, a tote for carrying and transporting a bottle or bottles, is provided. The tote includes a front panel defining a right side, a left side, a bottom, and a top terminal edge, and a rear panel defining a right side, a left side, a bottom, and a top terminal edge. The rear panel is secured to the front panel along at least the right side, the left side and the bottom terminal edges. The front and rear panels define a pocket therebetween. The front and/or rear panel is fabricated from an elastic, insulative, impact absorbent material. The tote has a substantially flattened condition when no bottle is disposed in the pocket thereof. Preferably, the front and rear panels are fabricated from neoprene. The front and rear panels may have a thickness of between about 3 mm to about 5 mm. Preferably, the neoprene is sandwiched between layers of stretch nylon. The bottom terminal edges of the front and rear panels are arcuate when the tote is in the flattened condition. Accordingly, when a bottle is at least partially inserted into the opening between the front and rear panels, the arcuate bottom terminal edge thereof flattens. Preferably, the front and rear panels are secured to one another by at least one of stitching, adhering, welding, and stapling. Desirably, at least one of the front and rear panels includes an aperture formed therein. The upper terminal edges of the front and rear panels may be arcuate. In one embodiment, the front panel and the rear panel are secured to one another along a contact line positioned between the right side terminal edges and the left side terminal edges thereof. The contact line divides the pocket between the front and rear panels into a first pocket and a second pocket. The bottom terminal edges of each of the front and rear panels is scalloped. Accordingly, a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket. In another embodiment, the tote further includes a third panel defining a right side, a left side, a bottom, and a top terminal edge. Accordingly, the right side terminal edge of the front panel is secured to the left side terminal edge of the rear panel, and a portion of the bottom terminal edge of the front panel is secured to the bottom terminal edge of the rear panel; the right side terminal edge of the rear panel is secured to the left side terminal edge of the third panels, and a portion of the bottom terminal edge of the rear panel is secured to a portion of the bottom terminal edge of the third panel; and the right side terminal edge of the third panel is secured to the left side terminal edge of the front panel, and a portion of the bottom terminal edge of the third panel is secured to a portion of the bottom terminal edge of the front panel. The front, rear and third panels may be secured to one another along a contact line substantially centrally located between the right and left side terminal edges of each of the front, the rear and the third panels. In yet another embodiment, the tote includes a first front panel defining a right side, a left side, a bottom, and a top terminal edge, and a first rear panel defining a right side, a left side, a bottom, and a top terminal edge. The first rear panel is secured to the first front panel along at least the right side, the left side and the bottom terminal edges. The first front and first rear panels are secured to one another along a first contact line positioned between the right side terminal edges and the left side terminal edges thereof. The first contact line defines a first pocket and a second pocket between the first front panel and the first rear panel. The bottom terminal edge of each of the first front and first rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the first pocket and a second lobe of the bottom terminal edge is in operative association with the second pocket. In the present embodiment, the tote further includes a second front panel defining a right side, a left side, a bottom, and a top terminal edge, and a second rear panel defining a right side, a left side, a bottom, and a top terminal edge, the second rear panel being secured to the second front panel along at least the right side, the left side and the bottom terminal edges. The second front and second rear panels are secured to one another along a second contact line positioned between the right side terminal edges and the left side terminal edges thereof. The second contact line defines a third pocket and a fourth pocket between the second front panel and the second rear panel. The bottom terminal edges of each of the second front and second rear panels is scalloped, wherein a first lobe of the bottom terminal edge is in operative association with the third pocket and a second lobe of the bottom terminal edge is in operative association with the fourth pocket. Preferably, the first contact line is secured to the second contact line. The tote may further include a tote strap for selectively engaging the tote. The tote strap includes a hook member for selectively engaging a support structure; and a loop extending from the hook member. The loop has sufficient length to be fed through the hand hold of the tote and for the hook member to then be fed through the loop. According to another aspect of the present disclosure, a tote for carrying and transporting a bottle or bottles is provided. The tote includes a front panel defining a perimetral edge; and a rear panel defining a perimetral edge. The front panel is secured to the rear panel along at least a portion of the perimetral edge so as to define a pocket therebetween and an opening into the pocket. The front and rear panels are fabricated from an elastic, insulative, impact absorbent material. The front and rear panels are preferably fabricated from neoprene laminated between two layers of stretch nylon. The front and rear panels are secured to one another along a contact line extending in a direction orthogonal to the opening. The contact line divides the pocket into a first and a second pocket, wherein the terminal edge opposite the opening is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped terminal edge. According to another aspect of the present disclosure, a carrier for transporting a bottle or bottles, is provided. The carrier includes a tote having a non-rigid front and rear panel secured to one another along a right side terminal edge, a left side terminal edge and a bottom terminal edge to thereby define a pocket having an open top. A contact line is provided between the right side terminal edge and the left side terminal edge to divide the pocket into a first and a second pocket. The bottom terminal edge is scalloped such that each of the first and second pockets is in operative association with a lobe of the scalloped bottom terminal edge, wherein the tote is fabricated from neoprene. | 20040402 | 20070522 | 20050714 | 67465.0 | 2 | BUI, LUAN KIM | TOTES FOR BOTTLES | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,735 | ACCEPTED | Method and apparatus for increasing the reliability of an emergency call communication network | The invention includes an emergency services network comprising a plurality of resources, a plurality of emergency services, and a Service/Name Resolution (SNR) system connected to a transport network. In operation, one of the resources receives a retrieval key for an emergency event from a conforming emergency system. The resource transmits the retrieval key to the transport network. The SNR system receives the retrieval key over the transport network and identifies at least one of the emergency services corresponding with the retrieval key. The SNR system initiates the transfer of the retrieval key to the identified emergency services. The identified emergency services then perform services corresponding with the retrieval key. | 1. An emergency services network for providing emergency services, the emergency services network comprising: a plurality of emergency services connected to a transport network; a plurality of resources connected to the transport network, wherein one of the plurality of resources, responsive to receiving a retrieval key from a conforming emergency system, transmits the retrieval key to the transport network; and an SNR system connected to the transport network, the SNR system receives the retrieval key over the transport network, identifies at least one of the emergency services that corresponds with the retrieval key, and initiates the transfer of the retrieval key to the identified emergency services. 2. The emergency services network of claim 1 wherein: each identified emergency service receiving the retrieval key performs a service corresponding with the retrieval key. 3. The emergency services network of claim 2 wherein: at least one emergency service transmits information corresponding with the retrieval key to the one resource, the SNR system, or the conforming emergency system responsive to receiving the retrieval key. 4. The emergency services network of claim 3 wherein the information comprises one of streaming video, streaming audio, graphics data, voice, text or binary data, or executable instructions or scripts. 5. The emergency services network of claim 2 wherein: at least one emergency service initiates a notification service responsive to receiving the retrieval key. 6. The emergency services network of claim 1 wherein the SNR system determines if the identified emergency services are available. 7. The emergency services network of claim 1 wherein the SNR system initiates the transfer of the retrieval key to the identified emergency services by: the SNR system transmitting a message to the one resource indicating the identified emergency services; and the one resource receiving the message from the SNR system, and transmitting queries that include the retrieval key to the identified emergency services. 8. The emergency services network of claim 7 wherein: at least one of the identified emergency services responds to the queries by transmitting information corresponding with the retrieval key to the one resource; and the one resource receives the information corresponding with the retrieval key and transmits the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 9. The emergency services network of claim 7 wherein at least one of the identified emergency services responds to the queries by transmitting information corresponding with the retrieval key to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 10. The emergency services network of claim 7 wherein one of the identified emergency services initiates a notification service for notifying third parties of an emergency event responsive to a query. 11. The emergency services network of claim 1 wherein the SNR system initiates the transfer of the retrieval key to the identified emergency services by: the SNR system transmitting queries that include the retrieval key to the identified emergency services. 12. The emergency services network of claim 11 wherein: at least one of the identified emergency services responds to the queries by transmitting information corresponding with the retrieval key to the SNR system; the SNR system receives the information corresponding with the retrieval key and transmits the information to the one resource; and the one resource receives the information corresponding with the retrieval key and transmits the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 13. The emergency services network of claim 11 wherein one of the identified emergency services initiates a notification service for notifying third parties of the emergency event responsive to a query. 14. The emergency services network of claim 11 wherein at least one of the queries to one of the identified emergency services includes an instruction to transmit information to the one resource. 15. The emergency services network of claim 14 wherein: the one identified emergency service responds to the one query by transmitting information corresponding with the retrieval key to the one resource; and the one resource receives the information corresponding with the retrieval key and transmits the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 16. The emergency services network of claim 11 wherein at least one of the queries to one of the identified emergency services includes an instruction to transmit information to the conforming emergency system. 17. The emergency services network of claim 16 wherein: the one identified emergency service responds to the one query by transmitting information corresponding with the retrieval key to the conforming emergency system. 18. The emergency services network of claim 1 wherein: the SNR system receives connection data for a new emergency service to establish communications with the new emergency service. 19. The emergency services network of claim 18 wherein connection data includes a network address for the new emergency service. 20. The emergency services network of claim 18 wherein: the SNR system receives a list of retrieval keys having a subscription in the new emergency service, and registers the list of retrieval keys in a database. 21. The emergency services network of claim 1 wherein the one resource comprises a response gateway. 22. The emergency services network of claim 1 wherein the conforming emergency system comprises a computer system in one of a Public Safety Answering Point (PSAP), a hospital, a police department, a fire station, a fire alarm company, a security company, an ambulance service, a state 9-1-1 coordinator, the Federal Emergency Management Agency (FEMA), the Department of Homeland Security, the National Geophysical Data Center, or the Center for Disease Control (CDC). 23. The emergency services network of claim 1 wherein the plurality of emergency services includes at least one of an ALI database, a Mobile Positioning Center (MPC), a Gateway Mobile Location Center (GMLC), an Emergency Auxiliary Service Provider (EASP), and a Voice over Internet Protocol (VoIP) server. 24. The emergency services network of claim 1 wherein the retrieval key comprises one of a telephone number, a network address, a Session Initiation Protocol (SIP) address, a trunk ID, a social security number, a street address, an employee ID, an email address, or an incident ID. 25. The emergency services network of claim 1 wherein the transport network comprises a packet network. 26. The emergency services network of claim 25 wherein the packet network comprises an Internet Protocol (IP) network. 27. The emergency services network of claim 1 wherein at least one of the emergency services receives update information pushed by the conforming emergency system. 28. A method of operating an emergency services network for providing emergency services, the emergency services network comprising a plurality of resources, a plurality of emergency services, and an SNR system connected to a transport network, the method comprising the steps of: receiving a retrieval key in one of the plurality of resources from a conforming emergency system (CES); transmitting the retrieval key from the one resource to the transport network; and receiving the retrieval key in the SNR system over the transport network, identifying at least one of the emergency services that corresponds with the retrieval key, and initiating the transfer of the retrieval key to the identified emergency services. 29. The method of claim 28 further comprising the step of: performing a service corresponding with the retrieval key in each identified emergency service receiving the retrieval key. 30. The method of claim 29 further comprising the step of: transmitting information corresponding with the retrieval key from at least one emergency service to the one resource, the SNR system, or the conforming emergency system responsive to receiving the retrieval key. 31. The method of claim 30 wherein the information comprises one of streaming video, streaming audio, graphics data, voice, text or binary data, or executable instructions or scripts. 32. The method of claim 29 further comprising the step of: initiating a notification service responsive to receiving the retrieval key in at least one emergency service. 33. The method of claim 28 further comprising the step of: determining if the identified emergency services are available in the SNR system. 34. The method of claim 28 wherein the step of initiating the transfer of the retrieval key to the identified emergency services comprises: transmitting a message from the SNR system to the one resource indicating the identified emergency services; and receiving the message in the one resource from the SNR system, and transmitting queries that include the retrieval key to the identified emergency services. 35. The method of claim 34 further comprising the steps of: responding to the queries in at least one of the identified emergency services by transmitting information corresponding with the retrieval key to the one resource; and receiving the information corresponding with the retrieval key in the one resource and transmitting the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 36. The method of claim 34 further comprising the step of: responding to the queries in at least one of the identified emergency services by transmitting information corresponding with the retrieval key to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 37. The method of claim 34 further comprising the step of: initiating a notification service in one of the identified emergency services for notifying third parties of an emergency event responsive to a query. 38. The method of claim 28 wherein the step of initiating the transfer of the retrieval key to the identified emergency services comprises: transmitting queries that include the retrieval key from the SNR system to the identified emergency services. 39. The method of claim 38 further comprising the steps of: responding to the queries in at least one of the identified emergency services by transmitting information corresponding with the retrieval key to the SNR system; receiving the information corresponding with the retrieval key in the SNR system and transmitting the information to the one resource; and receiving the information corresponding with the retrieval key in the one resource and transmitting the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 40. The method of claim 38 further comprising the step of: initiating a notification service in one of the identified emergency services for notifying third parties of the emergency event responsive to a query. 41. The method of claim 38 wherein at least one of the queries to one of the identified emergency services includes an instruction to transmit information to the one resource. 42. The method of claim 41 further comprising the steps of: responding to the one query in the one identified emergency service by transmitting information corresponding with the retrieval key to the one resource; and receiving the information corresponding with the retrieval key in the one resource and transmitting the information to the conforming emergency system to facilitate the conforming emergency system in handling an emergency event. 43. The method of claim 38 wherein at least one of the queries to one of the identified emergency services includes an instruction to transmit information to the conforming emergency system. 44. The method of claim 43 further comprising the step of: responding to the one query in the one identified emergency service by transmitting information corresponding with the retrieval key to the conforming emergency system. 45. The method of claim 28 further comprising the step of: receiving connection data for a new emergency service in the SNR system to establish communications with the new emergency service. 46. The method of claim 45 wherein connection data includes a network address for the new emergency service. 47. The method of claim 45 further comprising the steps of: receiving a list of retrieval keys having a subscription in the new emergency service; and registering the list of retrieval keys in a database. 48. The method of claim 28 wherein the one resource comprises a response gateway. 49. The method of claim 28 wherein the conforming emergency system comprises a computer system in one of a Public Safety Answering Point (PSAP), a hospital, a police department, a fire station, a fire alarm company, a security company, an ambulance service, a state 9-1-1 coordinator, the Federal Emergency Management Agency (FEMA), the Department of Homeland Security, the National Geophysical Data Center, or the Center for Disease Control (CDC). 50. The method of claim 28 wherein the plurality of emergency services includes at least one of an ALI database, a Mobile Positioning Center (MPC), a Gateway Mobile Location Center (GMLC), an Emergency Auxiliary Service Provider (EASP), and a Voice over Internet Protocol (VoIP) server. 51. The method of claim 28 wherein the retrieval key comprises one of a telephone number, a network address, a Session Initiation Protocol (SIP) address, a trunk ID, a social security number, a street address, an employee ID, an email address, or an incident ID. 52. The method of claim 28 wherein the transport network comprises a packet network. 53. The method of claim 52 wherein the packet network comprises an Internet Protocol (IP) network. 54. The method of claim 28 further comprising the step of: receiving update information in at least one of the emergency services pushed by the conforming emergency system. 55. An SNR system for an emergency services network, the SNR system comprising: a database comprising a directory correlating retrieval keys to emergency services in the emergency services network; and a processing system connected to the database, the processing system, responsive to receiving a retrieval key, accesses the database to identify at least one of a plurality of emergency services in the emergency services network that corresponds with the retrieval key, and initiates the transfer of the retrieval key to the identified emergency services. 56. The SNR system of claim 55 wherein: the processing system accesses the database to determine if the identified emergency services are available. 57. The SNR system of claim 55 wherein the processing system initiates the transfer of the retrieval key to the identified emergency services by: the processing system transmitting a message to a resource of the emergency services network indicating the identified emergency services. 58. The SNR system of claim 55 wherein the processing system initiates the transfer of the retrieval key to the identified emergency services by transmitting queries that include the retrieval key to the identified emergency services. 59. The SNR system of claim 58 wherein: the processing system receives the information from at least one of the identified emergency services, and transmits the information to a resource of the emergency services network. 60. The SNR system of claim 58 wherein: the processing system receives the information from at least one of the identified emergency services, and transmits the information to a conforming emergency system connected to the emergency services network. 61. The SNR system of claim 58 wherein at least one of the queries includes an instruction to transmit the information to a resource of the emergency services network. 62. The SNR system of claim 58 wherein at least one of the queries includes an instruction to transmit the information to a conforming emergency system connected to the emergency services network. 63. The SNR system of claim 55 wherein: the processing system receives connection data for a new emergency service to establish communications with the new emergency service. 64. The SNR system of claim 63 wherein connection data includes a network address for the new emergency service. 65. The SNR system of claim 63 wherein: the processing system receives a list of retrieval keys having a subscription in the new emergency service, and registers the list of retrieval keys in the database. 66. The SNR system of claim 55 wherein the plurality of emergency services includes at least one of an ALI database, a Mobile Positioning Center (MPC), a Gateway Mobile Location Center (GMLC), an Emergency Auxiliary Service Provider (EASP), and a Voice over Internet Protocol (VoIP) server. 67. The SNR system of claim 55 wherein the retrieval key comprises one of a telephone number, a network address, a Session Initiation Protocol (SIP) address, a trunk ID, a social security number, a street address, an employee ID, an email address, or an incident ID. 68. A method of operating an SNR system for an emergency services network, the SNR system comprising a database having a directory that correlates retrieval keys to emergency services in the emergency services network, the method comprising the steps of: receiving a retrieval key; accessing the database to identify at least one of a plurality of emergency services in the emergency services network that corresponds with the retrieval key; and initiating the transfer of the retrieval key to the identified emergency services. 69. The method of claim 68 further comprising the step of: accessing the database to determine if the identified emergency services are available. 70. The method of claim 68 wherein the step of initiating the transfer of the retrieval key to the identified emergency services comprises: transmitting a message to a resource of the emergency services network indicating the identified emergency services. 71. The method of claim 68 wherein the step of initiating the transfer of the retrieval key to the identified emergency services comprises: transmitting queries that include the retrieval key to the identified emergency services. 72. The method of claim 71 further comprising the step of: receiving the information from at least one of the identified emergency services, and transmitting the information to a resource of the emergency services network. 73. The method of claim 71 further comprising the step of: receiving the information from at least one of the identified emergency services, and transmitting the information to a conforming emergency system connected to the emergency services network. 74. The method of claim 71 wherein at least one of the queries includes an instruction to transmit the information to a resource of the emergency services network. 75. The method of claim 71 wherein at least one of the queries includes an instruction to transmit the information to a conforming emergency system connected to the emergency services network. 76. The method of claim 68 further comprising the step of: receiving connection data for a new emergency service to establish communications with the new emergency service. 77. The method of claim 76 wherein connection data includes a network address for the new emergency service. 78. The method of claim 76 further comprising the step of: receiving a list of retrieval keys having a subscription in the new emergency service; and registering the list of retrieval keys in the database. 79. The method of claim 68 wherein the plurality of emergency services includes at least one of an ALI database, a Mobile Positioning Center (MPC), a Gateway Mobile Location Center (GMLC), an Emergency Auxiliary Service Provider (EASP), and a Voice over Internet Protocol (VoIP) server. 80. The method of claim 68 wherein the retrieval key comprises one of a telephone number, a network address, a Session Initiation Protocol (SIP) address, a trunk ID, a social security number, a street address, an employee ID, an email address, or an incident ID. | RELATED APPLICATIONS This non-provisional application claims priority to U.S. provisional application 60/552,831, which was filed on Mar. 13, 2004. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to emergency services, and in particular to an enhanced emergency services network that reduces the time required to obtain the data necessary to handle an emergency event. This invention further relates to an enhanced emergency services network which reduces the time required to determine the physical location of a calling station. The invention still further relates to an enhanced emergency services network having facilities of increased flexibility for obtaining the information required to handle an emergency event. The invention still further relates to an emergency services network which enables the introduction of new emergency services and which associates such new emergency services with emergency events served by the emergency services network. 2. Statement of the Problem In the United States, basic 9-1-1 service is an emergency reporting service where a calling party can dial 9-1-1 in emergency situations. The call is answered at a Public Safety Answering Point (PSAP, also known as a “Public Safety Access Point”). An operator at the PSAP converses with the calling party to determine information on the emergency situation. For instance, the operator may ask the calling party for his/her name, the nature of the emergency, and the location of the emergency, etc. Based on the information gathered by the operator, the operator then contacts emergency personnel to respond to the emergency. Enhanced 9-1-1 service (E9-1-1) has the added feature of automatically providing the operator with some information on the calling party. For instance, E9-1-1 service includes the added features of Automatic Number Identification (ANI) and Automatic Location Identification (ALI). With Automatic Number Identification (ANI), the operator is automatically provided with telephone number of the phone placing the call for emergency services (e.g., a 9-1-1 call). With Automatic Location Identification (ALI), the PSAP, or another device, queries an ALI database for information on the physical location of the calling party's phone. An ALI database stores records of telephone numbers. A record in the ALI database contains information (such as a street address) on a physical location that corresponds with a telephone number. Responsive to a query from the PSAP, the ALI database returns the location information for the calling party. With the telephone number and the location information, the operator can more effectively handle the emergency call. Other countries have emergency services similar to this. Traditional communication networks have a rigid architecture for providing emergency services. In a traditional communication network, a PSAP connects to a pair of ALI databases in the emergency services network. The PSAP connects to each ALI database over a dedicated point-to-point connection. The ALI databases are the only resources in the emergency services network that connect with the PSAP and that can serve a request from the PSAP. The PSAP is dependant on the pair of ALI databases as the interface to the emergency services network. Traditional emergency services networks are vulnerable to undesirable delay in providing the PSAP with the information for handling emergency calls. For example, if the PSAP receives an emergency call, the PSAP queries the ALI database (using the ANI for the emergency call) for location information on the calling party. If the ALI database contains information for the ANI, then the ALI database may promptly return location information to the PSAP. However, if the ALI database does not contain information for the ANI (such as for a wireless call), then the ALI database needs to access other databases or systems to retrieve information for the ANI. The ALI database may not know which other databases or systems contain information for the ANI. Based on the ANI, the ALI database can transmit a query to a database or system that is more likely to contain information for the ANI. For instance, if the ANI indicates a wireless number for a particular wireless carrier, then the ALI database may transmit a query to a Mobile Positioning Center (MPC) or a Gateway Mobile Location Center (GMLC) for that wireless carrier. An MPC receiving the query may have to forward the query to another database, and so on until a database or system is reached that includes information for the ANI. The ALI database may spend precious time querying multiple databases or systems trying to locate information for an ANI. Also, the ALI database may not know of new databases or systems that have been added to the emergency services network that can provide valuable information or services. The network structure is very tightly connected (via dedicated connections), and the addition of new emergency services requires an extensive re-work of network components. Unfortunately, the ALI database takes time in finding what databases or systems contain information for the ANI. Also, the interchange of information between the ALI database and other databases consumes a finite amount of time during which the information required by the PSAP is not immediately available. Such delays are undesirable in emergency services networks, as the PSAPs need information as soon as possible to best handle emergency calls. SUMMARY OF THE SOLUTION The invention helps solve the above and other problems with an emergency services network that includes a Service/Name Resolution (SNR) system. The SNR system includes a directory correlating retrieval keys to emergency services in the emergency services network. The SNR system may quickly and efficiently identify emergency services that contain information for a retrieval key (or otherwise correspond with the retrieval key), and initiate the transfer of the retrieval key to the emergency services. The SNR system also provides a simpler and more efficient way of adding new emergency services and associating new emergency services with emergency events. One embodiment of the invention comprises an emergency services network that includes a plurality of resources, a plurality of emergency services, and an SNR system connected to a transport network. In operation, one of the resources receives a retrieval key from a conforming emergency system (e.g., a PSAP). The resource transmits the retrieval key to the transport network. The SNR system receives the retrieval key over the transport network and identifies at least one of the emergency services corresponding with the retrieval key. The SNR system then initiates the transfer of the retrieval key to the identified emergency services. One or more of the identified emergency services receiving the retrieval key performs a service corresponding with the retrieval key. In some embodiments, a service performed by an identified emergency service may be transmitting information corresponding with the retrieval key to the SNR system, the resource, or the conforming emergency system responsive to receiving the retrieval key. In other embodiments, a service performed by an identified emergency service may be notifying third parties of an emergency event. The invention may include other networks, systems, and methods described below. DESCRIPTION OF THE DRAWINGS The same reference number represents the same element on all drawings. FIG. 1 illustrates a communication network that provides emergency services in the prior art, such as 9-1-1 service in the United States. FIG. 2A illustrates a communication network in an exemplary embodiment of the invention. FIG. 2B is a flow chart illustrating a method in an exemplary embodiment of the invention. FIG. 3 illustrates an SNR system in an exemplary embodiment of the invention. FIG. 4A is a flow chart illustrating a method in an exemplary embodiment of the invention. FIG. 4B is a flow chart illustrating another method in an exemplary embodiment of the invention. FIG. 4C is a flow chart illustrating another method in an exemplary embodiment of the invention. FIG. 5 illustrates another communication network in an exemplary embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION Description of the Prior Art FIG. 1 illustrates a prior art communication network 100 that provides emergency services. Communication network 100 includes a telephone 102, a selective router (SR) 104, a Public Safety Answering Point (PSAP) 106, and an emergency services network 108. Emergency services network 108 includes two ALI databases 121-122, a Mobile Positioning Center (MPC) 124 (or a Gateway Mobile Location Center (GMLC)), a supplemental information provider 128, and other backend resources (not shown). Although a single MPC 124 and a single supplemental information provider 128 are illustrated in FIG. 1, emergency services network 108 generally includes multiple MPCs and supplemental information providers. As shown in FIG. 1, telephone 102 is connected to selective router 104. Selective router 104 is connected to PSAP 106 and ALI databases 121-122. PSAP 106 is connected to ALI databases 121-122. ALI database 121 is connected to ALI database 122, MPC 124, and supplemental information provider 128. ALI database 122 is connected to ALI database 121, MPC 124, and supplemental information provider 128. Paired ALI databases 121-122 are used in emergency services networks, such as emergency service network 108, to add redundancy and reliability into the network. Each PSAP 106 (only one is shown) connects to two ALI databases 121-122. For the PSAP-ALI interface, PSAP 106 is connected to ALI database 121 by a dedicated point-to-point connection 131, and is connected to ALI database 122 by a dedicated point-to-point connection 132. The PSAP-ALI interface traditionally includes fixed point-to-point data circuits utilizing asynchronous data modems for the dedicated connections 131-132. In newer versions of the PSAP-ALI interface, dedicated connections 131-132 may include an upgraded transport protocol, such as Internet Protocol (IP) or X.25. Regardless of the transport protocol, the logical connections between PSAP 106 and ALI databases 121-122 remain point-to-point dedicated connections 131-132. To illustrate how communication network 100 operates, assume that a caller dials 9-1-1 or a similar emergency number on telephone 102. Selective router 104 receives the emergency call, such as through a central office (not shown), a tandem switch (not shown), etc. Selective router 104 also receives an Emergency Service Number (ESN) associated with the location of the calling party from one or more ALI databases 121-122 or from another database (not shown). In FIG. 1, based on the ESN, selective router 104 selects PSAP 106 to handle the call and routes the emergency call to PSAP 106. Networks may route the emergency call to PSAP 106 in different ways depending on the desired implementation. Some examples of different implementations are illustrated in U.S. Pat. No. 6,415,018, U.S. Pat. No. 6,584,307, U.S. Pat. No. 6,385,302, and U.S. Pat. No. 6,587,545, which are all incorporated herein by reference to the same extent as if fully set forth herein. Emergency services network 108, which provides E9-1-1 services, includes Automatic Location Identification (ALI) services. When PSAP 106 receives the emergency call, PSAP 106 also receives an ANI for the call. The ANI, which is the telephone number of the calling party telephone 102, allows an operator in PSAP 106 to call the calling party back if the call happens to be terminated. The ANI also allows the PSAP 106 to fetch information on the physical location of the calling party in order to dispatch the appropriate emergency personnel (e.g., police, ambulance, fire department). To fetch the location information, PSAP 106 generates a request for the location information that includes the ANI of telephone 102, and forwards the request to ALI database 121 over dedicated connection 131. PSAP 106 may forward the request to ALI database 122 over dedicated connection 132 in addition to forwarding the request to ALI database 121 or instead of forwarding the request to ALI database 121. ALI database 121 receives the request for location information that includes the ANI. ALI database 121 searches for location information corresponding with the ANI. If ALI database 121 finds location information corresponding with the ANI, then ALI database 121 responds to PSAP 106 with the location information. If ALI database 121 does not find location information corresponding with the ANI, then ALI database 121 may have to query other ALI databases or other databases or systems for the location information. ALI database 121 acts as an intermediary between PSAP 106 and the other emergency services in emergency services network 108. PSAP 106 does not directly connect with emergency services other than ALI databases 121-122. PSAP 106 communicates with MPC 124 and supplemental information provider 128 through one or both of ALI databases 121-122. For instance, if telephone 102 is a mobile phone, then ALI database 121 queries MPC 124 or another MPC (not shown) for location information corresponding with the ANI and forwards the location information to PSAP 106. ALI database 121 may provide supplemental information provider 128 with the ANI, and supplemental information provide 128 may provide services such as notifying third parties of the emergency call. In each of these cases, ALI database 121 interfaces PSAP 106 with the other emergency services. When PSAP 106 receives a response from ALI database 121, PSAP 106 should be better informed to handle the emergency call. For instance, PSAP 106 should have location information for the calling party. PSAP 106 then informs the appropriate emergency personnel of the emergency call so that the emergency personnel can be quickly dispatched. One problem with current emergency services networks is that the PSAP-ALI interface uses dedicated point-to-point connections 131-132 between PSAP 106 and ALI databases 121-122. PSAP 106 is not able to dynamically connect with another ALI database (not shown) or another resource in emergency services network 108. PSAP 106 is dependant on the pair of ALI databases 121-122 to provide information for an emergency call. If one of the ALI databases 121 were to be taken out of service for maintenance or upgrades, then PSAP 106 would be connected to a single ALI database 122 and become one-sided. If the remaining ALI database 122 was to go out of service, then PSAP 106 would not be able to adequately service emergency calls. Emergency services administrators try to avoid architectures that rely on a single device or system because of the higher possibility of a service outage. Another problem with current emergency services networks is the traditional PSAP-ALI interface uses a limited message set. Most conventional PSAPs fundamentally include the same design as when they were initially conceived in the 1970's. The conventional PSAPs are configured to receive a fixed-length, pre-defined text string. The fixed-length text string limits the number of fields and the size of the fields that can be included in the text string. The small size of the text stream severely constrains the amount of information that the ALI database can provide to the PSAP, the context that can be created, and the data types that can be supported. Emergency services administrators have had to “overload” the text string, using the same fixed-length field for multiple purposes in different contexts, to provide the current services. New services or new capabilities are very difficult to add if the text string is overloaded by the current services. For instance, an ALI database would not be able to provide or would only be able to provide very limited individual medical information to the PSAP. Also, the technology does not lend itself to streaming video to the PSAP as the traditional message set does not have the capacity. Another problem with current emergency services networks is that the PSAP-ALI interface model is a request-response model. The PSAP forwards a request for ALI information to the ALI database, and the ALI database provides a response to the PSAP. Under the current model, the PSAP has to initiate communication with the ALI database with a request for ALI information. The ALI database is not allowed or equipped to initiate a communication with the PSAP, or deliver ALI information to the PSAP unless the PSAP submits a request. The current PSAP-ALI interface model limits the types of enhanced services provided by the emergency services network. Another problem with current emergency services network is that they are vulnerable to undesirable delay in providing the PSAP with the information for handling emergency calls. When an ALI database receives a request for information on an ANI, the ALI database may not know which databases or systems in emergency services network contain information for the ANI. The ALI database may spend precious time querying multiple databases or systems trying to locate information for an ANI. Also, the ALI database may not know of new databases or systems that have been added to the emergency services network that can provide valuable information or services. The following example illustrates some of the problems and limitations of the current emergency services networks. Assume that telephone 102 comprises a mobile telephone and that a user of telephone 102 dials 9-1-1. Selective router 104 routes the 9-1-1 call to PSAP 106. PSAP 106 submits a request to ALI database 121 for information for the 9-1-1 call. The request includes an ANI. Responsive to receiving the request, ALI database 121 determines that the ANI is a pseudo-ANI corresponding with a wireless service provider for telephone 102. The ANI is not the actual telephone number of telephone 102, but is a key corresponding with basic information identifying the wireless service provider and/or identifying the cell tower from which the 9-1-1 call originated. Because the pseudo-ANI is for a wireless service provider, ALI database 121 does not have location information for the pseudo-ANI. Consequently, ALI database 121 cannot immediately provide the location information to PSAP 106 because it must attempt to retrieve location information for telephone 102. ALI database 121 may not know which databases or systems contain location information for telephone 102. ALI database 121 does know that the pseudo-ANI is for a particular wireless carrier, so ALI database 121 transmits the pseudo-ANI to the MPC of GMLC for the wireless carrier (assume MPC 124). If MPC 124 does not contain information for telephone 102, then MPC 124 queries another database, and so on until location information is found. The database containing location information transmits the location information to ALI database 121. Because the PSAP-ALI interface allows only one response to a request, ALI database 121 attempts to collect all call information before responding to PSAP 106. ALI database 121 also attempts to ensure that PSAP 106 receives a response within a reasonable amount of time. Before submitting the request to MPC 124, ALI database 121 sets a timer to indicate how long it will wait for MPC 124 to respond. If MPC 124 responds within the time period, then ALI database 121 responds to PSAP 106 with the location information on telephone 102. The location information may be approximate X, Y coordinates (longitude and latitude) of telephone 102 (assuming a wireless Phase II system). If MPC 124 does not respond within the time period, then ALI database 121 responds to PSAP 106 with basic call information. The basic call information does not specify the location of telephone 102. The basic call information may merely be information on the wireless service provider or information on the cell tower from which the 9-1-1 call originated. If MPC 124 responds to ALI database 121 with the location information after ALI database 121 has already responded to PSAP 106 with the basic information, ALI database 121 cannot provide the location information on telephone 102 to PSAP 106. As previously stated, ALI database 121 cannot transmit information to PSAP 106 unless PSAP 106 has previously transmitted a request to ALI database 121 that remains unanswered. To obtain the location information from ALI database 121, PSAP 106 will have to submit another request to ALI database 121 for the same information (sometimes referred to as a re-bid). If ALI database 121 receives another request from PSAP 106, then ALI database 121 will need to determine whether to send the previous location information received from MPC 124, request new location information from MPC 124, handle time-out scenarios, and handle situations where this request may be for a new 9-1-1 call using the same pseudo-ANI. This scenario is further complicated because the ALI database 121 does not know when this call ends and another call with the same pseudo-ANI begins. Thus, ALI database 121 uses an elaborate scheme of timers to determine if the information received from MPC 124 is stale, and determines whether it should return the information for subsequent requests from PSAP 106 or whether it should submit new requests to MPC 124. While ALI database 121 is requesting information from MPC 124 and PSAP 106 is waiting for a response, PSAP 106 may be connected with a calling party possibly engaged in a life or death situation where any bit of information might help determine the best course of action. ALI database 121 cannot tell that it takes more time to determine location information for telephone 102 because of technology overhead. PSAP 106 may have to wait 10 to 15 seconds to be told nothing more than that the 9-1-1 call is a wireless call. The PSAP-ALI interface puts the PSAP operator in a guessing game. The PSAP operator does not know when the wireless call location information becomes available and does not know how often re-bids should be submitted to receive initial or new information. PSAP operators are taught not to push the re-bid button repeatedly in hopes of getting caller information, as this could have the opposite effect and swamp ALI database 121 or MPC 124 in a manner such that PSAP 106 cannot receive a response. The PSAP may also query supplemental information systems that are not part of emergency services network 108. For instance, some PSAPs maintain a separate database of supplemental information associated with particular telephone numbers, such as medical information, presence of animals, etc. The separate databases do not interoperate with the emergency services network 108. When an operator of the PSAP receives an emergency call, the operator manually queries the separate databases for supplemental information associated with the telephone number. Unfortunately, setting up and maintaining these separate and independent databases is difficult and inefficient. As is illustrated above, the current emergency services networks use old technology, are not very flexible in updating or improving existing services, and are not readily expandable to add new and better services. The importance of emergency services networks demands that these networks evolve to provide the best and most reliable services. Description of the Invention FIGS. 2A-2B, 3, 4A-4C, and 5 and the following description depict specific embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects of the invention have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. FIG. 2A illustrates an emergency services network 200 in an exemplary embodiment of the invention. Emergency services network 200 includes a plurality of resources 221-223, a plurality of emergency services 231-233, and a Service/Name Resolution (SNR) system 240 connected to a transport network 210. Resource 221 is illustrated as being connected to a conforming emergency system (CES) 201. Emergency services network 200 may include other devices, resources, systems, SNR systems, or emergency services not shown in FIG. 2A for the sake of brevity. FIG. 2A is intended to illustrate emergency services network 200 in a more functional manner than a physical manner. Depending on the embodiment, resource 221 may be part of CES 201, may be part of emergency services 231-233, or an independent system. A conforming emergency system comprises any system, device, or equipment configured to communicate according to the message set used by an emergency services network to access emergency services (not shown) to handle emergency events. One example of a conforming emergency system is a computer system for a Public Safety Answering Point (PSAP) conforming to the message set used by an emergency services network. A PSAP is known in the art of emergency services as a location where an emergency call (e.g., a 9-1-1 call) is answered. Another example of a conforming emergency system is a computer system for a hospital, a police department, a fire station, a fire alarm company, a security company, an ambulance service, a state 9-1-1 coordinator, the Federal Emergency Management Agency (FEMA), the Department of Homeland Security, the National Geophysical Data Center, the Center for Disease Control (CDC), etc, that conforms to the message set used by an emergency services network and is used to access in emergency services to handle emergency events. An emergency event comprises any instance or situation where a request for emergency services may be made. Examples of an emergency event include any abbreviated number call (e.g., a 9-1-1 call in the U.S., a 3-1-1 call in the U.S., and a 1-1-2 call in Europe), any call or request from a computer, a PDA, a TDD device, or any other device for emergency services, an email message, an SMS message, an Internet message, a call or signal to an emergency call center (e.g., an independent alarm service, OnStarg, etc), or any other request for emergency services. A transport network in this embodiment comprises any connection(s), path(s), etc for supporting a media channel, such as a packet network, an Internet Protocol (IP) network, a frame relay network, an X.25 network, an Asynchronous Transfer Mode (ATM) network, wireless connections, satellite connections, wireline connections, etc. A resource comprises any system, device, equipment, or server configured to communicate with a conforming emergency system via a media channel over a transport network to facilitate the handling of emergency events. An example of a resource includes a response gateway. A media channel comprises any communication path or paths (logical, virtual, or otherwise) over a transport network configured to transport data such as video, audio, voice, graphics, text data, binary data, executable instructions or scripts, etc. A media channel is not a physical or logical point-to-point dedicated connection over a transport network. The media channel may transport control messages or may operate in conjunction with a separate control channel. A response gateway comprises any system or server configured to communicate with a conforming emergency system via a media channel over a packet network, and interface the conforming emergency system with emergency services of an emergency services network. An emergency services network includes any network or networks that provide emergency services or facilitates a conforming emergency system in handling emergency events. Emergency services comprise any services subscribed to or provided for an emergency call or other event requiring such services. One example of an emergency service is an ALI database that provides location information. Another example of an emergency service is a Mobile Positioning Center (MPC) or a Gateway Mobile Location Center (GMLC) that provides location information for mobile devices. Another example of an emergency service is a Voice over Internet Protocol (VoIP) server or a selective transfer point determination system that provides location information for a VoIP phone or device. Another example of an emergency service is an Emergency Auxiliary Service Provider (EASP) or an Emergency Information Service that are general terms for any service provider that provides information or performs a function. For instance, an EASP may contain medical information for a subscriber and information on a subscriber's premises, such as a code to a front gate, guard dogs, hazardous materials, etc. The EASP may also include a third-party notification service that notifies third parties of an emergency event. The term “emergency service” is intended to include any accompanying structure that performs the emergency services, such as processing systems, computing platforms, network interfaces, servers, etc. The function of a resource may be included in or as part of an emergency service. Thus, a resource may also include an ALI database, an MPC, a GMLC, an EASP, a VoIP server, or any other emergency service. FIG. 2B is a flow chart illustrating a method 250 in an exemplary embodiment of the invention. In step 252, one of the resources 221-223 (illustrated as resource 221) receives a retrieval key from conforming emergency system 201. A retrieval key comprises any indicator, token, or key, such as a telephone number (including a dialed number, Emergency Service Routing Digits (ESRD), Emergency Service Routing Keys (ESRK), or any other string of digits according to the E.164 encoding scheme), a network address (including a Session Initiation Protocol (SIP) address, a MAC address, an IP address, a Universal Resource Identifier, or any other form of identification associated with a communication device), a trunk ID, a social security number, a street address, an employee ID, an email address, and an incident ID. Resource 221 transmits the retrieval key to transport network 210. In step 254, SNR system 240 receives the retrieval key over transport network 210. SNR system 240 identifies at least one of the emergency services 231-233 that corresponds with the retrieval key. In some embodiments, the function of identifying at least one of the emergency services 231-233 that corresponds with the retrieval key is a two-step process. In the first step, SNR system 240 determines which emergency services 231-233 may be associated with the retrieval key, such as by containing information for the retrieval key or having another subscription for the retrieval key (e.g., notification services). In the second step, SNR system 240 determines which of the emergency services associated with the retrieval key should be contacted based on any number of factors. One factor may be the type of information or service provided by the emergency service, such as a shell record for ALI information, information for a wireless call, notification service, information for a VoIP call, location information, etc. For example, if SNR system 240 determines that an ALI database contains a shell record for ALI information for the retrieval key, then SNR system 240 knows that it needs to obtain information for a wireless call from an MPC or GMLC. The second step helps avoid two emergency services from providing the same information or the same service for a retrieval key. In step 256, SNR system 240 initiates the transfer of the retrieval key to the identified emergency services 231-233. In step 258, each identified emergency service 231-233 receiving a retrieval key performs a service corresponding with the retrieval key. In some embodiments, each of the identified emergency services 231-233 do not necessarily perform a service, as some of the identified emergency services 231-233 may be redundant or the service may not be needed or available. In some embodiments, a service performed by an identified emergency service 231-233 may be transmitting information corresponding with the retrieval key to SNR system 240, resource 221, or conforming emergency system 201 responsive to receiving the retrieval key. In other embodiments, a service performed by an identified emergency service 231-233 may be notifying third parties of an emergency event. In some embodiments, resource 221 or CES 201 may have update information for a retrieval key. SNR system 240 operates as described above to identify the emergency services 231-233 corresponding with the retrieval key. With the emergency services identified, resource 221, CES 201, or SNR system 240 may push the update information to the emergency services 231-233. FIG. 3 illustrates an SNR system 240 in an exemplary embodiment of the invention. SNR system 240 includes a processing system 302 coupled to a database 304. Database 304 includes a directory correlating retrieval keys to emergency services 231-233 in emergency services network 200. SNR system 240 may include other systems, components, devices, etc, not shown in FIG. 3. In operation, processing system 302 receives a retrieval key from resource 221 in emergency services network 200 (see FIG. 2A). Processing system 302 accesses database 304 to identify at least one of emergency services 231-233 corresponding with the retrieval key. Processing system 302 then initiates the transfer of the retrieval key to the identified emergency services 231-233. In order for database 304 to include the directory correlating retrieval keys to emergency services 231-233, emergency services 231-233 register the retrieval keys with SNR system 240 for which they contain information or that have subscribed to the emergency service. Emergency services 231-233 may also register other data with the retrieval keys, such as attributes of the emergency service, a format of the information contained in the emergency service, etc. Processing system 302 may update database 304 regularly on either a static basis or a dynamic basis. Static updating may be done periodically (once a week or month) as required. Dynamic updating is done more often to register information that frequently changes. Dynamic updating may be done for wireless carrier changes, subscriber service changes, subscriber number changes resulting from number portability, etc. In addition to updating data in database 304 for current emergency services, new emergency services may be added to emergency services network 200 (see FIG. 2A). To add a new emergency service, personnel for the new emergency service contact personnel for SNR system 240, or other authorities, seeking permission to add the new emergency service. If permission is obtained, the personnel for the new emergency service also obtain a pass key (or other authorization code) and connection data for accessing SNR system 240. Once the connection data for SNR system 240 is obtained, the new emergency service transmits connection data for the new emergency service to SNR system 240. The connection data may be a network address or some other indicator of how to communicate with systems and platforms supporting the new emergency service. The new emergency service also transmits a list of retrieval keys having a subscription in the new emergency service. For instance, the new emergency service may transmit a list of retrieval keys for which the new emergency service contains information, such as location information, medical information, etc. The new emergency service may also register other data with the retrieval keys, such as attributes of the emergency service, a format of the information contained in the emergency service, etc. SNR system 240 receives the connection data for a new emergency service to establish communications with the new emergency service. Processing system 302 of SNR system 240 registers the list of retrieval keys in database 304. Processing system 302 may then access database 304 responsive to receiving a retrieval key to identify the new emergency service as a potential service for the retrieval key. SNR system 240 may initiate the transfer of the retrieval key (step 256 in FIG. 2B) in multiple ways, some of which are illustrated in FIGS. 4A-4C as provided below. FIG. 4A is a flow chart illustrating a method 400 in an exemplary embodiment of the invention. In step 402, SNR system 240 transmits a message to resource 221 indicating the identified emergency services 231-233. In step 404, resource 221 receives the message from SNR system 240, and transmits queries that include the retrieval key to the identified emergency services 231-233. In step 406, at least one of the identified emergency services 231-233 transmit information corresponding with the retrieval key to resource 221 or CES 201 responsive to the queries. In some embodiments, one of the identified emergency services 231-233 initiates a notification service for notifying third parties of the emergency event responsive to a query. FIG. 4B is a flow chart illustrating a method 420 in an exemplary embodiment of the invention. In step 422, SNR system 240 transmits queries that include the retrieval key to the identified emergency services 231-233. In step 424, at least one of the identified emergency services 231-233 transmits information corresponding with the retrieval key to SNR system 240 responsive to the queries. In some embodiments, one of the identified emergency services 231-233 initiates a notification service for notifying third parties of the emergency event responsive to a query. In step 426, SNR system 240 receives the information from the identified emergency services 231-233, and transmits the information to resource 221 or CES 201. FIG. 4C is a flow chart illustrating a method 440 in an exemplary embodiment of the invention. In step 442, SNR system 240 transmits queries that include the retrieval key to the identified emergency services 231-233. The queries include an instruction to transmit the information to resource 221 or CES 201. In step 444, at least one of the identified emergency services 231-233 transmits information corresponding with the retrieval key to resource 221 or CES 201 responsive to the queries. In some embodiments, one of the identified emergency services 231-233 initiates a notification service for notifying third parties of the emergency event responsive to a query. FIG. 5 illustrates another communication network 500 in an exemplary embodiment of the invention. Communication network 500 includes a plurality of PSAPs 501-502, an Internet Protocol (IP) network 510, a Domain Name Server (DNS) 512, a Session Initiation Protocol (SIP) system 516, and an emergency services network 520. Emergency services network 520 includes a plurality of response gateways 521-523, SNR system 540, ALI databases 525, Mobile Positioning Centers (MPC) 526, and Emergency Auxiliary Service Providers (EASP) 527. PSAPs 501-502, DNS 512, SIP system 516, response gateways 521-523, SNR system 540, ALI databases 525, MPCs 526, and EASPs 527 are connected to packet network 510. Communication network 500 may include other devices, resources, or systems not shown in FIG. 5 for the sake of brevity, such as GMLCs. Domain name server 512 is known in the art as a system that resolves host names into IP addresses. SIP system 516 comprises any system that uses SIP to assist in dynamically establishing a media channel. Examples of SIP system 516 include a SIP proxy and a SIP server. ALI database 525 (may also be referred to as an ALI system or ALI server) is known in the art of emergency services as a system that provides information on the location of a calling party station (e.g., phone). MPC 526 is known in the art of emergency services as a system that provides information on the location of a mobile calling device (e.g., cell phone). EASP 527 comprises any emergency service configured to provide additional information for an emergency event, such as medical information, information on a subscriber's premises (e.g., guard dogs, hazardous materials, codes for a gate, etc), notify third parties of an emergency event, or provide any other services for an emergency services network. In operation, PSAP 501 needs to access emergency services network 520 in order to obtain information on an emergency call. Unlike prior networks, PSAP 501 does not have dedicated point-to-point connections with a pair of ALI databases to obtain the information. PSAP 501 has to dynamically establish a media channel with emergency services network 520 to obtain the information. To start, PSAP 501 initiates setup of a media channel with a response gateway 521-523 of emergency services network 520. PSAP 501 may initiate the setup of a media channel periodically based on a timer, may initiate the setup of a media channel responsive to an instruction from another device or system, or may initiate the setup of a media channel responsive to receiving an emergency call. PSAP 501 uses SIP to initiate the setup of the media channel. PSAP 501 generates an Invite message and transmits the Invite message over a TCP/IP connection to IP network 510. The TCP/IP connection may be a secure connection. The Invite message may include a host address, such as “RG@EmergProvider.com”. IP network 510 forwards the host address to DNS 512. DNS 512 resolves the host address in the Invite message to an IP address for SIP system 516, and IP network 510 forwards the Invite message to SIP system 516. Responsive to receiving the Invite message, SIP system 516 determines which of the response gateways 521-523 is available. SIP system 516 may include logic (not shown) that is able to monitor the availability of response gateways 521-523 and determine which of the response gateways 521-523 is available. Response gateways 521-523 may periodically update SIP system 516 as to their availability and status. SIP system 516 may also query other systems (not shown) having selection logic that is able to determine which of the response gateways 521-523 is available. SIP system 516 selects one of the response gateways 521-523 (assume response gateway 521). SIP system 516 identifies an IP address of the selected response gateway 521 and forwards the Invite message over IP network 510 to the IP address of the selected response gateway 521. Response gateway 521 receives the Invite message from SIP system 516 along with an IP address of PSAP 501. Response gateway 521 may authenticate PSAP 501 via a login and password, via a Public Key Infrastructure (PKI) exchange of digital signatures, via public key cryptography, etc. Response gateway 521 may also access the PSAP's authorization to determine specific services available and subscribed to by PSAP 501. Response gateway 521 negotiates with PSAP 501 or SIP system 516 regarding parameters associated with the media channel to be established. Response gateway 521 may use another protocol to facilitate the negotiation of the appropriate protocol or parameters related to the media channel, such as Session Description Protocol (SDP). SDP may be carried within SIP messages to facilitate the establishment of a media channel, the version of the protocol, or parameters associated with the media channel. SDP is one way that two end-points request a media channel and agree upon the nature of the media channel. If response gateway 521 and PSAP 501 agree on the parameters for the media channel, then response gateway 521 forwards an OK message to PSAP 501. PSAP 501 receives the OK message and initiates a process to dynamically establish a media channel. An example of initiating a process is setting up a Secure Sockets Layer (SSL) TCP/IP interface. SIP system 516 may broker any messages or negotiations between response gateway 521 and PSAP 501 instead of response gateway 521 and PSAP 501 communicating directly. If the selected response gateway 521 is not able to accept the media channel, then SIP system 516 or another device forwards the Invite message to another response gateway 522-523. The Invite message is forwarded to response gateways 522-523 until a response gateway is found that can accept the media channel. With the media channel established, PSAP 501 and response gateway 521 may exchange messages over the media channel to help PSAP 501 handle an emergency call. In many cases, PSAP 501 will multiplex multiple messages over the media channel. PSAP 501 and response gateway 521 may use any compatible transport protocol, such as TCP/IP, HTTP, XML, and RTP. PSAP 501 and response gateway 521 may encrypt any transmitted messages for security purposes. The function of response gateway 521 is to interface PSAP 501 with emergency services in emergency services network 520. Thus, PSAP 501 transmits a message to response gateway 521 that includes an ANI for the emergency call. In other embodiments, a retrieval key or a key other than an ANI may be used, such as a SIP address, a URI, etc. Response gateway 521 transmits the ANI to SNR system 540. Based on the ANI, SNR system 540 identifies which emergency services (e.g., ALI database 525, MPC 526, and/or EASP 527) in emergency services network 520 have information corresponding with the ANI of the emergency call and the emergency services with which the ANI is associated, such as by subscription. SNR system 540 may identify all emergency services corresponding with the ANI, or may identify a sub-set of the emergency services based on any number of factors, such as the type of information contained in the emergency services. SNR system 540 may then operate in multiple ways responsive to identifying the emergency services corresponding with the ANI. In a first embodiment, SNR system 540 transmits a message to response gateway 521 identifying the emergency services that correspond with the ANI. Assume that MPC 526 and EASP 527 correspond with the ANI. Responsive to the message from SNR system 540, response gateway 521 transmits queries that include the ANI to MPC 526 and EASP 527. MPC 526 and EASP 527 then transmit information corresponding with the ANI to response gateway 521 responsive to the queries. Response gateway 521 receives the information from MPC 526 and EASP 527 and transmits the information to PSAP 501 to handle the emergency call. In some embodiments, MPC 526 and EASP 527 may transmit information corresponding with the ANI to PSAP 501 directly. In a second embodiment, SNR system 540 transmits queries that include the ANI to MPC 526 and EASP 527. MPC 526 and EASP 527 then transmit information corresponding with the ANI to SNR system 540 responsive to the queries. SNR system 540 receives the information from MPC 526 and EASP 527 and transmits the information to response gateway 521. Response gateway 521 receives the information from SNR system 540 and transmits the information to PSAP 501 to handle the emergency call. In some embodiments, SNR system 540 may transmit the information to PSAP 501 directly. In a third embodiment, SNR system 540 transmits queries that include the ANI to MPC 526 and EASP 527. The queries also include instructions to transmit information to response gateway 521. For instance, the instruction may include an address for response gateway 521 instead of an address for SNR system 540. MPC 526 and EASP 527 may then transmit information corresponding with the ANI to response gateway 521 responsive to the queries. Response gateway 521 receives the information from MPC 526 and EASP 527 and transmits the information to PSAP 501 to handle the emergency call. In some embodiments, the queries may include instructions for MPC 526 and EASP 527 to transmit information directly to PSAP 501. When response gateway 521 communicates with ALI database 525, MPC 526, and EASP 527, response gateway 521 may establish a media channel with each of ALI database 525, MPC 526, and EASP 527. Response gateway 521 may use SIP system 516 to establish the media channel as previously described. The media channels with ALI database 525, MPC 526, and EASP 527 may also be pre-established. The same goes for SNR system 540. In conclusion, the embodiments of the invention described herein illustrate that an SNR system in an emergency services network provides many advantages over the prior art. | <SOH> BACKGROUND OF THE INVENTION <EOH>1. Field of the Invention This invention relates to emergency services, and in particular to an enhanced emergency services network that reduces the time required to obtain the data necessary to handle an emergency event. This invention further relates to an enhanced emergency services network which reduces the time required to determine the physical location of a calling station. The invention still further relates to an enhanced emergency services network having facilities of increased flexibility for obtaining the information required to handle an emergency event. The invention still further relates to an emergency services network which enables the introduction of new emergency services and which associates such new emergency services with emergency events served by the emergency services network. 2. Statement of the Problem In the United States, basic 9-1-1 service is an emergency reporting service where a calling party can dial 9-1-1 in emergency situations. The call is answered at a Public Safety Answering Point (PSAP, also known as a “Public Safety Access Point”). An operator at the PSAP converses with the calling party to determine information on the emergency situation. For instance, the operator may ask the calling party for his/her name, the nature of the emergency, and the location of the emergency, etc. Based on the information gathered by the operator, the operator then contacts emergency personnel to respond to the emergency. Enhanced 9-1-1 service (E9-1-1) has the added feature of automatically providing the operator with some information on the calling party. For instance, E9-1-1 service includes the added features of Automatic Number Identification (ANI) and Automatic Location Identification (ALI). With Automatic Number Identification (ANI), the operator is automatically provided with telephone number of the phone placing the call for emergency services (e.g., a 9-1-1 call). With Automatic Location Identification (ALI), the PSAP, or another device, queries an ALI database for information on the physical location of the calling party's phone. An ALI database stores records of telephone numbers. A record in the ALI database contains information (such as a street address) on a physical location that corresponds with a telephone number. Responsive to a query from the PSAP, the ALI database returns the location information for the calling party. With the telephone number and the location information, the operator can more effectively handle the emergency call. Other countries have emergency services similar to this. Traditional communication networks have a rigid architecture for providing emergency services. In a traditional communication network, a PSAP connects to a pair of ALI databases in the emergency services network. The PSAP connects to each ALI database over a dedicated point-to-point connection. The ALI databases are the only resources in the emergency services network that connect with the PSAP and that can serve a request from the PSAP. The PSAP is dependant on the pair of ALI databases as the interface to the emergency services network. Traditional emergency services networks are vulnerable to undesirable delay in providing the PSAP with the information for handling emergency calls. For example, if the PSAP receives an emergency call, the PSAP queries the ALI database (using the ANI for the emergency call) for location information on the calling party. If the ALI database contains information for the ANI, then the ALI database may promptly return location information to the PSAP. However, if the ALI database does not contain information for the ANI (such as for a wireless call), then the ALI database needs to access other databases or systems to retrieve information for the ANI. The ALI database may not know which other databases or systems contain information for the ANI. Based on the ANI, the ALI database can transmit a query to a database or system that is more likely to contain information for the ANI. For instance, if the ANI indicates a wireless number for a particular wireless carrier, then the ALI database may transmit a query to a Mobile Positioning Center (MPC) or a Gateway Mobile Location Center (GMLC) for that wireless carrier. An MPC receiving the query may have to forward the query to another database, and so on until a database or system is reached that includes information for the ANI. The ALI database may spend precious time querying multiple databases or systems trying to locate information for an ANI. Also, the ALI database may not know of new databases or systems that have been added to the emergency services network that can provide valuable information or services. The network structure is very tightly connected (via dedicated connections), and the addition of new emergency services requires an extensive re-work of network components. Unfortunately, the ALI database takes time in finding what databases or systems contain information for the ANI. Also, the interchange of information between the ALI database and other databases consumes a finite amount of time during which the information required by the PSAP is not immediately available. Such delays are undesirable in emergency services networks, as the PSAPs need information as soon as possible to best handle emergency calls. | <SOH> SUMMARY OF THE SOLUTION <EOH>The invention helps solve the above and other problems with an emergency services network that includes a Service/Name Resolution (SNR) system. The SNR system includes a directory correlating retrieval keys to emergency services in the emergency services network. The SNR system may quickly and efficiently identify emergency services that contain information for a retrieval key (or otherwise correspond with the retrieval key), and initiate the transfer of the retrieval key to the emergency services. The SNR system also provides a simpler and more efficient way of adding new emergency services and associating new emergency services with emergency events. One embodiment of the invention comprises an emergency services network that includes a plurality of resources, a plurality of emergency services, and an SNR system connected to a transport network. In operation, one of the resources receives a retrieval key from a conforming emergency system (e.g., a PSAP). The resource transmits the retrieval key to the transport network. The SNR system receives the retrieval key over the transport network and identifies at least one of the emergency services corresponding with the retrieval key. The SNR system then initiates the transfer of the retrieval key to the identified emergency services. One or more of the identified emergency services receiving the retrieval key performs a service corresponding with the retrieval key. In some embodiments, a service performed by an identified emergency service may be transmitting information corresponding with the retrieval key to the SNR system, the resource, or the conforming emergency system responsive to receiving the retrieval key. In other embodiments, a service performed by an identified emergency service may be notifying third parties of an emergency event. The invention may include other networks, systems, and methods described below. | 20040402 | 20061017 | 20050915 | 61795.0 | 0 | WOO, STELLA L | METHOD AND APPARATUS FOR INCREASING THE RELIABILITY OF AN EMERGENCY CALL COMMUNICATION NETWORK | UNDISCOUNTED | 0 | ACCEPTED | 2,004 |
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10,816,875 | ACCEPTED | Actuator | The actuator is capable of greatly deforming a flexible sheet member. The actuator comprises: a flexible sheet member being made of a polymer material; and a pair of electrodes being respectively provided on both faces of the sheet member, the electrodes being made of carbon nano fibers. | 1. An actuator, comprising: a flexible sheet member being made of a polymer material; and a pair of electrodes being respectively provided on both faces of said sheet member, said electrodes being made of carbon nano fibers. 2. The actuator according to claim 1, wherein one end of the carbon nano fibers constituting said electrodes bite into said sheet member. 3. The actuator according to claim 1, wherein the polymer material is polyurethane resin. 4. The actuator according to claim 1, wherein the polymer material is silicone resin. 5. A material for electrodes of an actuator, which comprises a flexible sheet member made of a polymer material and a pair of the electrodes respectively provided on both faces of the sheet member, being made of carbon nano fibers. | BACKGROUND OF THE INVENTION The present invention relates to an actuator and a material for electrodes of the actuator, more precisely relates to an actuator capable of greatly deforming a sheet member made of a polymer material by applying an electric field and a material for electrodes of the actuator. An actuator having a flexible sheet member made of a polymer material and a pair of electrodes respectively provided on both faces of said sheet member has been known. The sheet member is deformed by applying an electric field. For example, a conventional actuator is disclosed in Japanese Patent Gazette No. 2000-49397. The actuator is shown in FIG. 17. The actuator 10 has a one-layer polyurethane film 12 and a pair of electrodes 11 respectively provided on both faces of the polyurethane film 12. Deformation (bending electrostriction) is occurred by applying an electric field to the actuator 10. The electrodes 11 are formed on the both faces of the polyurethane film 12 by evaporating gold. When the electrodes 11 are formed by evaporating gold, fine particles of gold are stuck onto surfaces of the polyurethane film 12. By applying the electric field to the actuator 10, the actuator 10 bends as shown in FIG. 18. Therefore, the actuator 10 can be used to actuate other members. By employing the bending action, various kinds of actuators can be realized. However, the deformation is so small, e.g., curvature 1/R=36 m−1 (see the Japanese patent gazette), that usage of the actuator must be much limited. The inventors of the present invention studied and found that the deformation of the actuator was limited by a structure of the electrodes 11. Namely, the electrodes 11 are formed by evaporating gold, so the fine particles of gold are stuck on the polyurethane film 12 by evaporation and keep contact each other. When the actuator 10 having such electrodes 11 is deformed, the electrodes 11 are cracked so that electric conduction is stopped. Therefore, the actuator 10 cannot be greatly deformed itself. If the electrodes 11 are made thick so as not to be cracked, the polyurethane film 12 cannot bend. SUMMARY OF THE INVENTION An object of the present invention is to provide an actuator capable of greatly bending a flexible sheet member. Another object of the present invention is to provide a material for electrodes of the actuator of the present invention. To achieve the objects, the present invention has following structures. Namely, the actuator of the present invention comprises: a flexible sheet member being made of a polymer material; and a pair of electrodes being respectively provided on both faces of the sheet member, the electrodes being made of carbon nano fibers. In the actuator, one end of the carbon nano fibers constituting the electrodes may bite into the sheet member. In the actuator, the polymer material may be, for example, polyurethane resin, silicone resin, etc. The material for electrodes of the actuator is made of carbon nano fibers. In the present invention, the electrodes are made of carbon nano fibers, which are merely contact each other, so that the electrodes can be flexible and can fully follow deformation of the sheet member with maintaining mutual contact. Therefore, the actuator can maximally deform the sheet member. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which: FIG. 1 is an explanation view showing a schematic structure of an actuator of the present invention; FIG. 2 is an explanation view on the basis of video images showing deformation of the actuator having a polyurethane sheet member, wherein 100 V is inputted to the actuator; FIG. 3 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 150 V is inputted to the actuator; FIG. 4 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 200 V is inputted to the actuator; FIG. 5 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 300 V is inputted to the actuator; FIG. 6 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 400 V is inputted to the actuator; FIG. 7 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 500 V is inputted to the actuator; FIG. 8 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 600 V is inputted to the actuator; FIG. 9 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 700 V is inputted to the actuator; FIG. 10 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 800 V is inputted to the actuator; FIG. 11 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member, wherein 900 V is inputted to the actuator; FIG. 12 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member including electrolyte, wherein 800 V is inputted to the actuator whose electrodes are made of carbon nano fibers; FIG. 13 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member including electrolyte, wherein 800 V is inputted to the actuator whose electrodes are made of polypyrrole; FIG. 14 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member including no electrolyte, wherein 800 V is inputted to the actuator whose electrodes are made of carbon nano fibers; FIG. 15 is an explanation view on the basis of video images showing deformation of the actuator having the polyurethane sheet member including no electrolyte, wherein 800 V is inputted to the actuator whose electrodes are made of polypyrrole; FIG. 16 is an explanation view on the basis of video images showing deformation of the actuator having a silicone film, wherein 800 V is inputted to the actuator; FIG. 17 is an explanation view showing the structure of the conventional actuator; and FIG. 18 is an explanation view showing the deformation of the conventional actuator. DETAILED DESCRIPTION OF THE EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. An actuator of the present embodiment is shown in FIG. 1. The actuator 20 has a sheet member 22 made of a flexible polymer material. A pair of electrodes 24, which are mainly made of carbon nano fibers, are respectively provided on the both side faces of the sheet member 22. The electrodes 24 may be formed to cover the whole side faces of the sheet member 22 or formed into prescribed patterns. In FIG. 1, the electrodes 24 are formed to cover the whole side faces of the sheet member 22 with uniform thickness. By applying an electric field from one end to another electrode 24, the sheet member 22 is greatly bended. If the electrodes 24 are patterned, the sheet member 22 can be optionally deformed. The polymer material of the sheet member 22 is not limited. For example, polyurethane, especially polyurethane whose soft segment includes polyester may be employed (see Japanese Patent Gazette 2000-49397). Further, silicone gel, poly vinyl chloride, polyethylene, polypropylene, PET, etc. may be employed as the polymer material. Conventionally, in the actuator which is deformed by applying an electric field, a material, whose molecules are oriented by a DC electric field, e.g., polyurethane elastomer having polycarbonate polyol, is employed as the polymer material (see Japanese Patent Gazette No. 7-240544). However, in the present embodiment, the improved electrodes 24 can greatly deform so polymer materials, whose crystals have no orientation, can be employed. Note that, a plasticizer may be added to the polymer so as to make a flexible polymer material. Preferably, a little electrolyte, e.g., salt, is doped to the polymer material. By adding the electrolyte, an electric current of nA level can pass through the polymer material when the electric field is applied. Namely, the polymer material may have electroconductivity, which is as small as that of a semiconductor. Even in a polymer material having perfect insulativity, e.g., silicone gel, by doping the electrolyte, the material can be relatively greatly deformed when the electric field is applied. A material of the electrodes 24 is carbon nano fibers. For example, carbon nano tubes, which are formed by a vapor growth process, may be employed as the carbon nano fibers. The carbon nano fibers formed by the vapor growth process are very fine fibers having diameter of dozens nm to one hundred and dozens nm and length of less than 20 um. Preferably, the material of the electrodes 24 is constituted by carbon nano fibers only. But carbon components, e.g., graphite, carbon, may be added to the carbon nano fibers. The electrodes 24, which is formed by the material mainly made of carbon nano fibers, are respectively provided on the both side faces of the sheet member 22, which is made of the flexible polymer material. Methods of forming the electrodes 24 will be explained. Firstly, a first method will be explained. Carbon nano fibers are dispersed in a solvent, e.g., ethanol, to form into paste. The paste is applied on the both side faces of the sheet member 22 and dried. The dried carbon nano fiber layers become the electrodes 24. Then, surfaces of the electrodes 24 are pressed by pressing means, e.g., a roller, so as to completely adhere the electrodes 24 on the side faces of the sheet member 22. By pressing the electrode 24, one end of the carbon nano fibers bite into the side faces of the sheet member 22. Note that, the carbon nano fibers may be coated with layers of electroconductive resin so as to prevent the carbon nano fibers from falling off. As described above, the carbon nano fibers are very fine fibers, and the electrodes 24 are made of many carbon nano fibers. Unlike the conventional electrode made of fine particles of gold, even if the sheet member 22 is greatly deformed, the flexible carbon nano fibers constituting the electrodes 24 can follow the deformation of the sheet member 22 without separating each other. Namely, the mutual contact of the carbon nano fibers can be maintained while the electrodes 24 follow the deformation of the sheet member 22. Since the electrodes 24 are not cracked and broken even if the sheet member 22 is greatly deformed, function of the electrodes 24 can be maintained. Therefore, the sheet member 22 can be greatly deformed. Note that, the sheet member 22 is originally greatly deformable. In the present embodiment, the electrodes 24 are made of the flexible carbon nano fibers, which are capable of following the deformation of the sheet member 22 with maintaining their mutual contact, the sheet member 24 can be maximally deformed. As described above, one end of the carbon nano fibers can bite into the side faces of the sheet member 22 by pressing the electrodes 24 with, for example, the roller. The inventors think that the ends of the carbon nano fibers biting into the sheet member 22 emit electrons when the electric field is applied to the electrodes 24. Carbon fibers formed by the vapor growth process have been used as fibers for a field electron emitter. Electrons are emitted from sharp ends of the carbon fibers when a high electric field is applied. The inventors found that electrons concentratedly emitted from the ends of the carbon nano fibers toward an inner solid or gel part of the sheet member 22 when the electric field is applied to the electrodes 24. With this action, the sheet member 22 can be effectively deformed or bended. The inventors think that electric charges asymmetrically exist in both edge parts of the sheet member 22, so that one edge part is contracted and the other edge part is extended. Therefore, the polymer material of the sheet member 22 is bended. As described above, the ends of the carbon nano fibers bite into the sheet member 22, and electrons are emitted from the ends toward the inner part of the sheet member 22. With this action, electric charges can be effectively charged, so that the asymmetrical existence of electric charges can be promoted. Therefore, the sheet member 22 can be deformed with high responsibility. The electrodes 24 may be made of powderlike material (aggregated) too. In this case, the electrodes 24 are formed by uniformly scattering the powders onto the side faces of the sheet member 22 and pressing the powders with, for example, a roller. For example, silicone gel has viscous surfaces, the powders can be adhered on the side faces of the sheet member 22 made of the silicone gel so that the electrodes 24 can be formed. If the electrodes 24 are pressed, ends of the carbon nano fibers can bite into the side faces of the sheet member 22. Successively, a second method of forming the electrodes 24 will be explained. Powders of a material (carbon nano fibers) are uniformly scattered on a flat steel plate. Then, an electric field is applied to the steel plate. By applying the electric field, the carbon nano fibers stands up. In this state, silicone gel is fed on the upper face of the steel plate and solidified, so that a flexible sub-sheet member having an electrode can be formed on the steel plate. The sub-sheet member having the electrode is peeled from the steel plate. Further, another sub-sheet member having an electrode is formed on another steel plate by the same manner. Rear faces of the two sub-sheet members, on which no electrodes are formed, are mutually adhered, so that the actuator 20 having the flexible sheet member and a pair of the electrodes can be formed. In the both processes, the electrodes can be formed much easier than the conventional electrodes, which are formed by evaporating gold. Thickness of the electrodes 24 are not limited. As described above, the carbon nano fibers are gathered and contact each other, so that mutual contact of the carbon nano fibers can be maintained even if the sheet member 22 is deformed. As far as the carbon nano fibers contact each other, the sheet member 22 is made thinner so as to give higher flexibility. Further, the thin actuator 20 can reduces manufacturing cost. The thin actuator may be transparent or semitransparent, so they can be used as actuators of many kinds of optical apparatuses. Examples of the actuator will be explained. EXAMPLE 1 Example 1 is respectively shown in FIGS. 2-11. FIGS. 2-11 are explanation views on the basis of video images showing the deformation of the actuators. In each example, the flexible sheet member was a polyurethane sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which sodium acetate was doped. The electrodes were made of carbon nano tubes and formed by the first method. Applied voltage was 100-900 V (0.5-4.5 MV/m). When the electric field was applied to one end of each actuator, the actuator immediately slightly deforms (see a symbol “On” in each drawing). By increasing the applied voltage, rate of the deformation was accelerated, and degree of the deformation was increased. Note that, in the drawings, symbols “5S” indicate the deformation of the actuators when five seconds elapsed from applying voltage, and symbols “15S” indicate the deformation of the actuators when fifteen seconds elapsed from applied voltage. As clearly shown in FIGS. 2-11, the sheet members, in each of which the electrodes were formed on the both side faces, were bended like arcs. In FIG. 11, 900 V is applied to the electrodes. Curvature of the maximum deformation 1/R was about 100 m−1 (a radius of curvature was about 10 mm). Therefore, a great deformation was attained. EXAMPLE 2 Example 2 is shown in FIG. 12. FIG. 12 is an explanation view on the basis of video images showing the deformation of the actuator. In this example, the flexible sheet member was a polyurethane sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which sodium acetate was doped. The electrodes were made of carbon nano tubes. Applied voltage was 800 V (4 MV/m). FIG. 12 shows deformation of the actuator immediately after inputting voltage and that after several seconds elapsed from applying voltage. A comparative example with respect to the Example 2 is shown in FIG. 13. FIG. 13 is an explanation view on the basis of video images showing the deformation of the actuator. In this comparative example, the flexible sheet member was a polyurethane sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which sodium acetate was doped. The electrodes were made of polypyrrole. Applied voltage was 800 V (4 MV/m). FIG. 13 shows deformation of the actuator immediately after applying voltage and that after several seconds elapsed from applying voltage. According to FIGS. 12 and 13, the deformation of the actuator, whose electrodes were made of carbon nano fibers, was much greater than that of the actuator, whose electrodes were made of polypyrrole. EXAMPLE 3 Example 3 is shown in FIG. 14. FIG. 14 is an explanation view on the basis of video images showing the deformation of the actuator. In this example, the flexible sheet member was a polyurethane sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which no electrolyte was doped. The electrodes were made of carbon nano tubes. Applied voltage was 800 V (4 MV/m). FIG. 14 shows deformation of the actuator immediately after applying voltage and that after several seconds elapsed from applying voltage. A comparative example with respect to the Example 3 is shown in FIG. 15. FIG. 15 is an explanation view on the basis of video images showing the deformation of the actuator. In this comparative example, the flexible sheet member was a polyurethane sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which no electrolyte was doped. The electrodes were made of polypyrrole. Applied voltage was 800 V (4 MV/m). FIG. 13 shows deformation of the actuator immediately after applying voltage and that after several seconds elapsed from applying voltage. According to FIGS. 14 and 15, the deformation of the actuator, whose electrodes were made of carbon nano fibers, was much greater than that of the actuator, whose electrodes were made of polypyrrole. However, the deformation of the actuators shown in FIGS. 12 and 13 were greater than those shown in FIGS. 14 and 15 due to the electrolytes. EXAMPLE 4 Example 4 is shown in FIG. 16. FIG. 16 is an explanation view on the basis of video images showing the deformation of the actuator. In this example, the flexible sheet member was a silicone sheet (width 5 mm, length 20 mm and thickness 0.20 mm), to which sodium acetate was doped. The electrodes were made of carbon nano tubes. Applied voltage was 800 V (4 MV/m). FIG. 14 shows deformation of the actuator immediately after applying voltage and that after several seconds elapsed from applying voltage. In the conventional actuator using a silicone sheet, no deformation was visually observed. By doping sodium acetate and employing the electrodes made of carbon nano tubes, the deformation of the actuator was clearly observed. The actuator of the present invention uses the deformation of the flexible sheet member, so it cannot be used as a large power actuator. But the actuator can be effectively used for a switch of a minute electric device, an angle-changing mechanism of a reflection mirror, etc. The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by he foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. | <SOH> BACKGROUND OF THE INVENTION <EOH>The present invention relates to an actuator and a material for electrodes of the actuator, more precisely relates to an actuator capable of greatly deforming a sheet member made of a polymer material by applying an electric field and a material for electrodes of the actuator. An actuator having a flexible sheet member made of a polymer material and a pair of electrodes respectively provided on both faces of said sheet member has been known. The sheet member is deformed by applying an electric field. For example, a conventional actuator is disclosed in Japanese Patent Gazette No. 2000-49397. The actuator is shown in FIG. 17 . The actuator 10 has a one-layer polyurethane film 12 and a pair of electrodes 11 respectively provided on both faces of the polyurethane film 12 . Deformation (bending electrostriction) is occurred by applying an electric field to the actuator 10 . The electrodes 11 are formed on the both faces of the polyurethane film 12 by evaporating gold. When the electrodes 11 are formed by evaporating gold, fine particles of gold are stuck onto surfaces of the polyurethane film 12 . By applying the electric field to the actuator 10 , the actuator 10 bends as shown in FIG. 18 . Therefore, the actuator 10 can be used to actuate other members. By employing the bending action, various kinds of actuators can be realized. However, the deformation is so small, e.g., curvature 1/R=36 m −1 (see the Japanese patent gazette), that usage of the actuator must be much limited. The inventors of the present invention studied and found that the deformation of the actuator was limited by a structure of the electrodes 11 . Namely, the electrodes 11 are formed by evaporating gold, so the fine particles of gold are stuck on the polyurethane film 12 by evaporation and keep contact each other. When the actuator 10 having such electrodes 11 is deformed, the electrodes 11 are cracked so that electric conduction is stopped. Therefore, the actuator 10 cannot be greatly deformed itself. If the electrodes 11 are made thick so as not to be cracked, the polyurethane film 12 cannot bend. | <SOH> SUMMARY OF THE INVENTION <EOH>An object of the present invention is to provide an actuator capable of greatly bending a flexible sheet member. Another object of the present invention is to provide a material for electrodes of the actuator of the present invention. To achieve the objects, the present invention has following structures. Namely, the actuator of the present invention comprises: a flexible sheet member being made of a polymer material; and a pair of electrodes being respectively provided on both faces of the sheet member, the electrodes being made of carbon nano fibers. In the actuator, one end of the carbon nano fibers constituting the electrodes may bite into the sheet member. In the actuator, the polymer material may be, for example, polyurethane resin, silicone resin, etc. The material for electrodes of the actuator is made of carbon nano fibers. In the present invention, the electrodes are made of carbon nano fibers, which are merely contact each other, so that the electrodes can be flexible and can fully follow deformation of the sheet member with maintaining mutual contact. Therefore, the actuator can maximally deform the sheet member. | 20040405 | 20060919 | 20050804 | 92130.0 | 0 | DOUGHERTY, THOMAS M | ACTUATOR | SMALL | 0 | ACCEPTED | 2,004 |
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